Papermaking belt and method of making the same using a textured casting surface.

A belt used in papermaking and a method of making the same using a patterned casting surface

Field of the invention

This invention relates generally to papermaking belts useful in paper machines for making strong, soft, absorbent paper products. This invention also relates to a method of making such a papermaking belt and papermaking methods using these belts. More specifically, the present invention relates to papermaking belts consisting of a resin lattice and a reinforcing structure having a texture on the side in contact with the machine, i.e. the back side. The texture is formed on the belt by casting a resin material over and through the reinforcing structure as the reinforcing structure passes over the textured surface.

Background of the invention

One of the predominant features of daily life in modern industrialized societies is the use of paper products for various purposes. Paper towels, face papers, toilet paper, etc. are in almost constant use. The high demand for such papers has created the need for improved product versions and their manufacturing methods. Despite major advances in papermaking, research and development continues to aim to improve both products and their manufacturing methods.

Paper products such as paper towels, face papers, toilet paper, etc. are made from one or more tissue webs. If the products are to fulfill their function and gain wide acceptance, the tissue webs from which they are made must have certain characteristic physical characteristics. The most important of these features of Tär97070 are strength, softness and absorbency.

Strength is the ability of paper to maintain its physical integrity during use.

Softness is a pleasant sensation that is observed when the paper is pressed in the hand and used for its purposes.

Absorbency is a property of paper that allows it to receive and retain fluids, especially water and aqueous solutions and suspensions. When assessing the absorbency of a paper, not only the absolute amount of liquid that a certain amount of paper retains is significant, but also the rate at which the paper absorbs the liquid. In addition, when the paper is formed into a product such as a towel or rag, the ability of the paper to cause liquid to enter the paper and thus leave a dry wiped surface is important.

In processes for making paper products for use in tissue, towel and sanitary products, an aqueous slurry of paper fibers is generally prepared and then dewatered from the slurry while rearranging the fibers in the slurry to form a paper web. Different types of equipment can be used to aid in the dewatering process.

Today, most manufacturing processes use machines known as either flat wire machines or double (flat) wire machines. In flat wire machines, the paper slurry is fed to the upper surface of a moving endless belt, which belt acts as the initial forming surface of the machine. In twin wire machines, the slurry is sandwiched between two converging flat wires, where the initial dewatering and rearrangement of the papermaking process is carried out.

After the initial formation of the paper web with the flat wire or wires, each type of machine generally conveys the paper web through the drying process or processes on another fabric in the form of an endless belt, often different from the flat wire or wires. This second fabric is sometimes called a drying fabric. Numerous arrangements consisting of one or more flat wires and one or more drying fabrics, as well as one or more drying processes, have been used successfully and to some extent less successfully. In one or more drying processes, mechanical compression of the paper web, removal of vacuum water, drying by blowing heated air through the paper web, and other types of procedures may be performed.

As can be seen from the above, papermaking belts or fabrics have different names according to their intended use. Plain wires, also called Four15 drinier belts, forming wires, or forming fabrics are tools used in the initial forming zone of a paper machine. As mentioned above, drying fabrics are fabrics that carry a paper web through the drying operation of a paper machine. Many other types of straps and fabrics are also possible. Most papermaking fabrics used in the past usually consist of a piece of woven fabric with the ends joined together by a seam to form an endless belt. Woven papermaking fabrics generally comprise a plurality of detachable longitudinal warp yarns and a plurality of detached transverse weft yarns woven together in a particular weave pattern. Previous belts have included fabrics comprising a single layer (of warp and weft yarns), multilayer fabrics, and fabrics having a few layers, each comprising interwoven warp and weft yarns. Initially, papermaker's fabric yarns were made from metal yarns consisting of materials such as phosphor bronze, bronze, stainless steel, mes35 ham, or combinations thereof. Often different materials were placed on and attached to the fabrics in an effort to make dewatering more efficient. Recently, in the papermaking industry, it has been found that synthetic materials can be used, in whole or in part, to form the underlying wire structures of better quality than forming wires made of metal wires. Such synthetic materials have been nylon, polyesters, acrylic fibers and copolymers. Although many different methods, fabrics, and arrangements of these fabrics have been used, only certain of these methods, fabrics, and fabric arrangements have resulted in commercially successful paper products.

One example of paper webs widely accepted by the consuming public are webs made by the method described in U.S. Patent 3,301,746 (Sanford and Sisson, January 31, 1967). Other widely accepted paper products are prepared by the method described in U.S. Patent 3,994,771 (Morgan and Rich, November 30, 1976). However, despite the high quality of the products produced by these methods, the search for even better products has continued, as mentioned above.

One commercially significant improvement to the aforementioned paper webs was made by the method described in U.S. Patent 4,529,480 (Trokhan, July 16, 1985), which is incorporated herein by reference. This improvement included the use of a papermaking belt (called a guide portion) consisting of a porous woven portion surrounded by a cured photosensitive resin lattice. The resin lattice was provided with several separate channels known as guide channels. The method in which this guide member was used included, among other steps, contacting the paper fiber primary web with the top surface of the guide member and directing a suction pressure or other liquid pressure difference to the web from the back of the guide member (machine contact side). The papermaking belt used in this method was called the guide section because the paper fibers are guided and arranged in the guide channels of the cured resin grid during the use of the liquid pressure difference. Using the above-mentioned improved papermaking method, it was finally possible to form paper with certain desired preselected properties, as mentioned below.

The guide member described in the aforementioned Trokhan patent was fabricated by the method described in U.S. Patent 4,514,345 to Johnson et al., Which is incorporated herein by reference. Johnson et al. the method described in the patent includes the following steps: 1) coating the porous woven element with a photosensitive resin; 2) adjusting the thickness of the photosensitive resin to a preselected value; 3) treating the resin with light having an activating wavelength through a mask containing opaque and transparent areas, and 4) removing the uncured resin. This method resulted in a guide section having a grid having a surface in contact with the paper web and a surface in contact with the machine, both of which were provided with a network pattern surrounding the channels that was substantially planar or smooth.

Paper made by the method described in U.S. Patent No. 4,529,480 is described in U.S. Patent No. 4,637,859 to Trokhan, which is incorporated herein by reference. This paper is characterized by having two physically distinct areas distributed on its surfaces. One of the areas is a continuous network area with a relatively high density and high specific strength. The second area is an area consisting of numerous domes completely surrounded by a network area. The images in the latter area have a relatively low density and a relatively low specific strength compared to the network area.

The paper made by the method described in U.S. Patent 4,529,480 was indeed stronger, softer and more absorbent than the paper made by the previous methods due to a few factors. The strength of the produced paper improved as a result of the relatively high specific strength provided by the network area. The softness of the produced paper increased as a result of the formation of numerous dents with an odor density of 10 on the surface of the paper. The absolute amount of liquid retained by the paper (one of the decisive factors determining the absorbency of the paper *) increased due to a decrease in the overall density of the paper.

Although the above-mentioned improved method worked quite well, it has been found that when the control part of the above-mentioned method passes over the vacuum device used for dewatering in the papermaking process, certain undesirable events occur. Of most concern was the large amount of partially dewatered fibers in the paper web passing completely through the guide section.

This led to the undesirable result that fairly mobile paper fibers clog the vacuum machinery used for dewatering. Another undesirable phenomenon was the tendency of these moving paper fibers to accumulate in the dewatering25 machinery to the extent that fiber lumps formed on the machinery. This accumulation of fibers caused wrinkles and creases, especially longitudinal creases, from forming previously smooth papermaking belts as the belts repeatedly passed over the dewatering process during the papermaking process, which not only resulted in serious problems with the moisture content of the papermaking paper.

The importance of the difficulties experienced with these previous belts was compounded by the relatively high price of the belts. In most cases, the manufacture of the porous woven element incorporated into these belts required (and still requires) expensive textile processing operations, including the use of large and expensive weaving machines. These woven elements also include considerable amounts of relatively expensive filaments. Belt costs continue to increase when heat-resistant filaments are used, which is generally necessary in the case of belts passing through a drying operation.

In addition to the cost of the belt itself, the failure of the papermaking belt also seriously affects the efficiency of the papermaking process. Frequent paper machine belt failures can have a significant impact on the economics of papermaking operations due to costly utilization losses (i.e., machine downtime) of the papermaking machine during the time the replacement belt is installed on the paper machine.

During the development of the papermaking process described in U.S. Patent No. 4,529,480, it was assumed that the network formed on the underside of the resin lattice (machine contact surface) had to be substantially planar to achieve the desired suction pressure abruptness required to guide and rearrange the fibers in

Without wishing to be bound by any theory, it is now hypothesized that the problems that arose with the use of previous smooth papermaking belts may have been due, at least in part, to the extremely abrupt application of suction pressure to the paper web as it passed over the dewatering vacuum machinery. It is assumed that previous papermaking prices with a smooth background actually formed a temporary barrier over the vacuum source. When the open channels (guide channels) of the previous type of papermaking belt were then approached, the suction pressure was applied to the highly loaded fibers of the fibrous web on top of the resin lattice extremely abruptly. The sudden effect of this suction pressure is believed to have caused the sudden deflection of the moving fibers, which has been sufficient to allow them to pass completely through the papermaking belt. It is also believed that this sudden effect of suction pressure and migration of fibers causes very small holes in the dome areas of the finished paper, which are undesirable in some, but not all, cat cases.

One theory regarding the excessive accumulation of paper fibers on the surfaces of vacuum dewatering equipment is that previous papermaking belts with smooth backgrounds did not have sufficient surface texture on the back side15. It is assumed that a certain amount of surface texture is necessary for such resin-coated belts to be able to remove paper fibers accumulating in the vacuum dewatering apparatus through the abrasive action of the belt passing over the vacuum dewatering apparatus.

As a result of the above, there is a need for an improved papermaking process that is not hampered by the undesired accumulation of these moving paper fibers in the vacuum dewatering machinery used in the process. Therefore, there is also a need for an improved papermaking belt and a method of making the same which eliminates the above-mentioned problems caused by the use of a papermaking belt made by previous methods.

Therefore, it is an object of the present invention to provide an improved papermaking process which substantially reduces or eliminates the migration of the aforementioned moving paper fibers.

It is also an object of the present invention to provide a papermaking belt which substantially reduces the problem associated with prior resin coated papermaking belts of accumulating paper fibers in a vacuum dewatering machine.

It is another object of the present invention to reduce the creasing of papermaking belts and subsequent breakage caused by the accumulation of paper fibers on the surface of the vacuum dewatering machinery used in the papermaking process.

It is also an object of the present invention to provide a papermaking process which results in the elimination of small holes in the dome areas of the finished paper web (unless such holes are a desirable feature of the paper being produced).

It is also an object of the present invention to provide a papermaking belt having passageways which form surface texture irregularities on the back side of the belt, and a method of making this passageway in which these passageways can be formed on the belt without sacrificing the strength of the entire papermaking belt.

It is a further object of the present invention to provide a papermaking belt having a longer service life when used in the papermaking process of the present invention than prior papermaking belts, and an economically viable method of making this papermaking belt.

These and other objects of the present invention will become more apparent from the following description and the accompanying drawings.

Summary of the Invention

The textured papermaking belt of the present invention generally consists of two main elements, a lattice and a reinforcing structure. When the papermaking belt of the present invention in a preferred form, it is an endless belt having a paper-contacting side and a textured backside, which is in contact with the paper side of the opposite side and in contact with the papermaking machinery used in the process. The grid is preferably a cured polymeric grid made of photosensitive resin having a first surface defining a surface in contact with the paper of the belt and a second surface opposite the first surface and channels passing between the first and second surfaces. the first surface of the grid is formed by the paper side network, which surrounds and defines the openings in the channels.

The second surface of the net defines at least a portion of the textured back side of the strap. the second surface of the grid is in addition to backside network with a distinctive channels of roads. These passages form a surface texture irregularities of the second surface of the backside verkos15 position. The reinforcing structure is placed between the first surface of the grid and at least a part of the second surface of the network, and its function is to strengthen the grid. The reinforcing structure has a paper-facing side and a machine coming from the side facing towards the paper side of the finish vastapuo20 Lella. The reinforcing structure also has pores and a reinforcing component having an open surface projection determined by the projection of the surfaces defined by the pores and a reinforcing surface projection determined by the projection of the reinforcing component. In one embodiment of the papermaking belt 25, all the passageways on the other surface of the grid are located outwards from a plane defined by the side of the reinforcing structure facing the machine. In another embodiment, a plurality of passageways the reinforcing structures located toward the plane defined by the side of the inside of the pores, so that a part of the routes surface of the projection corresponds to a part from the open surface of said reinforcing structure, and outside the plane defined by the machine-facing plurality of passageways disposed in the reinforcing structure side. In either embodiment, the backing surface has sufficient fluid transport capacity to allow at least about 1,800 standard cubic centimeters / minute to escape across the textured surface.

The method of making a papermaking belt according to the present invention comprises the following steps:

(a) providing a forming unit having a textured work surface;

(B) providing a reinforcing structure having a paper-facing side of the machine-facing side of the paper-side and the opposite side of the pore;

(c) contacting at least a portion of the machine-facing side of the reinforcing structure with the working surface of the forming unit;

(d) applying a liquid photosensitive resin coating to at least one side of the reinforcing structure such that the coating forms a first surface and a second surface and is distributed so that at least a portion of the second surface of the coating is positioned adjacent the forming surface of the forming unit; between the first and second surfaces and that part of the coating interposing between the first surface of the coating and the paper-facing surface of the reinforcing structure forms a resin overload, with at least a portion of the coating penetrating the texture of the work surface of the forming unit so that the textured surface defines areas of the second surface of the coating;

(e) adjusting the thickness of the overload to a preselected value;

(f) providing a mask having opaque and transparent areas, wherein the opaque areas, together with the transparent areas, define a preselected pattern in the mask;

(g) placing a mask between the liquid photosensitive resin coating and the actinic light source so that the mask is in contact with the first surface of the coating, the opaque areas of the mask protecting a portion of the coating from light sources emitted by the light source and other transparent areas leaving the transparent areas

(h) curing the unprotected portions of the liquid photosensitive resin coating and not curing the protected portions by exposing the liquid photosensitive resin coating to a light source through a mask to obtain a partially formed composite belt, and removing the uncured liquid resin; leaving a cured hart15 chip, surrounding at least a portion of the reinforcing structure, and wherein the grid has a plurality of channels in areas that the mask opaque areas are protected by the mentioned light rays, and the passageways that form the surface texture irregularities of said grid taus20 counterpart network, corresponding to the places where the second surface of the coating has penetrated into the forming unit of the working surface texture.

The method of making a strong, soft, absorbent paper web according to the present invention comprises the following steps:

(a) providing an aqueous dispersion of paper fibers;

(b) forming the paper fiber starting web from the dispersion on a porous surface;

(C) contacting the embryonic web into contact with the papermaking belt of the kek30 sinnön paper in contact with the finish-side;

(d) conveying the papermaking belt and the primary web over the vacuum source and directing the liquid pressure difference to the primary web by the vacuum source so that the liquid pressure difference is provided from the back of the papermaking belt through the papermaking belt ducts through the papermaking belt channels; staple fibers rearrange, wherein the paper fibers form an intermediate web under conditions such that the guidance is initiated at the latest at the same time as the removal of water from the elemental web;

(e) printing the web on the paper side into the intermediate product web by placing an intermediate web between the papermaking belt and the printing surface to form an interest-compressed paper fiber web, and (f) drying the interest-compressed web.

Brief description of the drawings

Figure 1 is a schematic representation of one embodiment of a continuous paper machine useful in carrying out the method of the present invention.

Fig. 1A is a simplified schematic cross-sectional view showing a partially formed fibrous web 20 of paper prior to being guided into the channel of a papermaking belt according to the present invention.

Fig. 1B is a simplified cross-sectional view of a portion of the primary web shown in Fig. 1A after the fibers of the primary web have been guided into one of the channels of the papermaking belt.

Figure 2 is a top view of a portion of a preferred embodiment of an improved papermaking belt in accordance with the present invention.

Fig. 3 is an enlarged cross-sectional view of a portion of the papermaking belt shown in Fig. 2 30 taken along line 3-3.

Fig. 4 is an enlarged cross-sectional view of a portion of the papermaking belt shown in Fig. 2 taken along line 4-4.

Figure 5 is a top plan view of a portion of an alternative embodiment of a papermaking belt according to the present invention having a single layer reinforcing structure.

Fig. 5A is a cross-sectional view of a portion of the papermaking belt shown in Fig. 5 taken along line 5A-5A.

Fig. 5B is a cross-sectional view of a portion of the papermaking belt shown in Fig. 5 taken along line 5B-5B.

Figure 6 is an enlarged and top view of one preferred woven multilayer reinforcing structure that may be used in the papermaking belt of the present invention.

Fig. 7 is an enlarged sectional view of the reinforcing structure shown in Fig. 6 taken along line 7-7 of Fig. 6.

Fig. 8 is an enlarged sectional view of the reinforcing structure shown in Fig. 6 taken along line 8-8 of Fig. 6.

Fig. 9 is an enlarged sectional view of the reinforcing structure shown in Fig. 6 taken along line 9-9 of Fig. 6.

Fig. 10 is an enlarged sectional view of this reinforcing structure shown in Fig. 6 taken along line 10-10 of Fig. 6.

Fig. 11 is an enlarged sectional view of the reinforcing structure shown in Fig. 6 taken along line 11-11 of Fig. 6.

Figure 12 is a top plan view of a portion of the reinforcing structure with a portion of the surrounding lattice in place around the reinforcing structure.

Fig. 12A is a side view of a portion of the reinforcing structure of Fig. 12 illustrating some passageways

II and the position of surface texture irregularities in relation to a few surface projections of the reinforcing structure.

Fig. 13 is a top view similar to Fig. 6 of the reinforcing structure illustrating a projection of a reinforcing surface of a portion of the reinforcing structure.

Fig. 14 is another view similar to Fig. 13 of a similar reinforcing structure seen from above, illustrating some projections of the warp surfaces of the reinforcing structure.

Fig. 15 is a side view similar to Fig. 8 of a reinforcing structure illustrating the projections of the warp surfaces shown in Fig. 14 seen from another angle.

Fig. 16 is a plan view similar to Figs. 13 and 14 of the reinforcing structure, illustrating some projections of the weft surfaces of the reinforcing structure.

Fig. 17 is an enlarged sectional view similar to Fig. 7 illustrating the projections of the tissue surfaces shown in Fig. 16 as viewed from another angle.

Fig. 18A is a plan view, similar to the previous top drawings, of the reinforcing structure, illustrating some projections of the knee regions of the reinforcing structure.

Fig. 18B is an enlarged side view, similar to Fig. 7, of a reinforcing structure illustrating some projections of the knee regions of the reinforcing structure as viewed from another angle.

Fig. 18C is an enlarged side view, similar to Fig. 8, of the reinforcing structure illustrating some projections of the knee regions of the reinforcing structure when viewed from another angle.

Fig. 19 is an enlarged schematic view of one preferred channel opening shape in connection with a papermaking belt according to the present invention.

Figs. 19A and 19B are a top plan view of the projection of the knee area of ​​the first surface and the projection of the knee area of ​​the second surface of the papermaking belt grid shown in Figs.

Figure 20 is an enlarged schematic view of another preferred shape of the channel opening.

Figure 21 is a greatly enlarged and exaggerated schematic sectional view of a portion of the papermaking belt and a reinforcing grid structure, which shows details of the passageways and surface texture irregularities in the backside.

Figures 22A, B and C are simplified schematic diagrams of different types of background textures that may occur on a papermaking belt.

Fig. 22D is a greatly enlarged view of a portion of a reinforcing component as shown in Figs. 22A to 22C showing some elevated portions of the reinforcing component.

Fig. 23A is an enlarged schematic diagram of the problems encountered when a papermaking belt without the improvements described herein encountered a vacuum dewatering20 during the papermaking process of the apparatus.

Fig. 23B is an enlarged diagrammatic view of the manner in which the papermaking belt of the present invention alleviates previously encountered problems.

Fig. 24 is a graph illustrating the application of suction pressure to both the papermaking belt with and without the background texture disclosed herein.

Fig. 25 is a schematic representation of a basic apparatus for making a papermaking belt according to the present invention.

Fig. 26 is an enlarged schematic view of the post-curing unit of the apparatus shown in Fig. 25.

Fig. 27 is an enlarged schematic diagram of an alternative forming unit used in a method of making a papermaking belt in accordance with the present invention, comprising a textured casting surface and an adaptive barrier film.

Fig. 28 is a schematic diagram showing the forming unit of Fig. 27, further enlarged to show in detail the manner in which the background texturing is formed during casting.

Fig. 29 is a schematic top view of two alternative embodiments of the casting drum shown in Fig. 27, in which the textured casting surface is alternatively formed by either placing strips of material or woven fabric (only a portion of which is visible) on the casting drum.

Fig. 30 is a schematic diagram of one alternative of the belt casting method of the present invention using a smooth casting drum and a textured barrier film as a casting surface.

Fig. 31 is a schematic diagram showing the forming unit of Fig. 30, further enlarged to show in detail the manner in which the texturing of the background 20 is formed during casting.

Figure 32 is a schematic top plan view of a portion of the testing apparatus used to measure air leakage across the papermaking belt of the present invention, the back side.

Fig. 33 is a side diagram of the test apparatus shown in Fig. 32.

Fig. 34 is a graphical representation of the calibration of a flow meter used in the apparatus shown in the previous two figures.

Fig. 35A is a top plan photograph, approximately 25 times magnified, above the papermaking belt without the improvements disclosed herein.

Fig. 35B is a top plan view, approximately 25 times magnified, of the back of a papermaking belt without the improvements disclosed herein.

Fig. 36A is a photograph magnified approximately 25 times above a papermaking belt made in accordance with an alternative embodiment of the present invention. The image is taken at an angle of about 35 degrees to the imaginary normal of the upper surface.

Fig. 36B is an approximately 25-fold magnified photograph of the back of the papermaking belt shown in Fig. 36A. The image is taken at an angle of about 35 degrees to the imaginary normal of the background surface.

Fig. 36C is a cross-sectional photograph of the papermaking belt shown in Figs. 36A and 36B, approximately 25 times magnified.

Fig. 37A is a photograph approximately 25 times magnified above a papermaking belt made in accordance with another alternative embodiment of the present invention. The image is taken at an angle of about 35 degrees to the imaginary normal of the upper surface.

Fig. 37B is a photograph of the background of the papermaking belt shown in Fig. 37A magnified about 25 times. The image is taken at an angle of about 35 degrees to the imaginary normal of the background surface.

Fig. 37C is a cross-sectional photograph of the papermaking belt shown in Figs. 37A and 37B magnified approximately 25 times.

Detailed description of the invention

The description includes the following parts in the order listed: a detailed description of the papermaking belt of the present invention; one basic method of making this papermaking belt and a few variations thereof, and a detailed description of the method of making paper according to the present invention.

1. The Papermaking Belt

In a typical papermaking machine illustrated in Figure 1, the papermaking belt of the present invention is in the form of an endless belt, papermaking belt 10. 1, the papermaking belt 10 carries a paper web (or fibrous web) in its various forming stages and passing the arrow B in a direction of the papermaking belt return rolls 19a, 19b, painojättötelan 20, paperinval5 mistushihnan return rolls 19c, 19d, 19e and 19f, and emulsion 21 above. The loop rotated by the papermaking belt 10 includes means for applying a liquid pressure difference to the paper web, such as a vacuum trap 24a and a multi-slot suction box 24. In Figure 1, the papermaking belt 10 also passes through a pre-dryer such as a blow dryer 26 and a jet roll 20

Although a preferred embodiment of the present invention is in the form of an endless belt, the present invention may be embodied in a number of other forms, including, for example, stationary sheets for use in making handmade sheets or rotating cylinders for use in other types of continuous processes. Regardless of the physical shape, the papermaking belt 10 generally has certain physical properties.

The general characteristics of the papermaking belt are shown in Figures 2-4. The papermaking belt (i.e., simply the belt) 10 of the present invention generally consists of two main elements: a lattice 32 (preferably a lattice made of cured polymeric photosensitive resin) and a reinforcing structure 33. When the papermaking belt is an endless belt, it generally has two opposite sides, referred to herein as the paper contacting side 11 and the textured backsheet, i.e. simply the backsheet 12. The backsheet 12 of the belt 10 is in contact with papermaking machinery such as vacuum catcher 24a and multi-slot suction 24. The grid 32 has a first surface 34, a second surface 20 opposite the first surface 34, and passages 36 between the first surface 34 and the second surface 35. The first surface 34 of the grid 32 contacts the fibrous webs to be dewatered and defines a belt in contact with the paper. of at least 11. the second side surface 35 of the belt 10 determines the portion of the textured backside 12. The passages 36 between the first surface 34 and the second surface 35 conduct water from the fibrous webs resting on the first surface 34 to the second surface 35 and provide areas where the fibers of the fibrous web can be directed and rearranged. Figure 2 shows that the network 32a comprises a fixed part of a grid 32 surrounding the channels 36 and defining a network-like pattern. As shown in Figure 2, the openings 42 of the channels 36 are arranged in the network 32a according to a preselected pattern. Figure 2 shows that a paper-side network 34a is formed on the first surface 34 of the grid 32, which surrounds and defines the openings of the channels 36 in the first surface 34 of the grid 32. As will be shown in Figure 36B, the framework 32 to the second surface 35 has a backside network 35a which surrounds and defines the grid 32 in the second surface 35 of the channels 36 of openings 43. Figures 3 and 4 show that the reinforcing structure 33 of the paper invalidation belt 10 of the present invention is generally shown to be at least partially surrounded by (or embedded in or enclosed in) a grid 32. More specifically, the reinforcing structure 33 is placed between the first surface 34 of the lattice 32 and at least a portion of the second surface 35 of the lattice 32. Figures 3 and 4 also show that the reinforcing structure 33 has a paper-facing side 51 and a machine-facing side 51 opposite the paper 52 per side. As shown in Figure 2, the reinforcing structure 33 has pores 39 and a reinforcing component 40. The reinforcing component 40 comprises portions of the reinforcing structure other than the pores 39 (i.e., the reinforcing structure 33

II fixed part). The reinforcing component 40 generally consists of a plurality of structural components 40a. The reinforcing structure 33 has a projection of the open surface determined by the projection of the surfaces defined by the pores 39 and a projection of the reinforcing surface determined by the projection of the reinforcing component 40. Figures 3 and 4 show that the second surface 32 of the grid 35 is a backside network 35a with a plurality of passageways 37 that provide surface texture irregularities in the network 38 of the framework 32 to the backside 35a. The passageways 37 are different paths than the channels 36 passing between the first surface 34 and the second surface 35 of the truss 32. The passageways 37 allow air to pass between the back surface 12 of the papermaking belt 10 and the surfaces of the vacuum dewatering equipment used in the papermaking process (such as vacuum trap 24a and suction box) when the dewatering equipment

The paper-contacting side 11 of the belt 10 shown in Figures 1-4 is the surface of the papermaking belt 10 that is in contact with the paper web to be dewatered and rearranged into the finished product. As shown in Fig. 1, the side of the belt 10 called the paper-contacting side 10 is called by this name even if it carries the paper web only in a part of each turn in the paper machine. The side of the belt 10 called the paper contacting side 11 is also consistently referred to by that name, although at some point in each turn (such as at the papermaking belt return roll 19d) it may temporarily come into contact with the machinery used in the papermaking process. The paper contacting side 11 of the belt 10 may also be referred to as the top surface of the belt 10 or the surface in contact with the elementary web. It is to be understood that, although the belt 10 with the paper-contacting side 11 may be referred to as the upper surface may be in contact with the paper-side orientation to be such that it is facing downwardly on the return path in a papermaking machine when the belt 10 is in the form of an endless belt. As shown in Figures 2-4, the paper contact side 11 of the belt 10 is generally formed entirely of the first surface 34 of the grid 32.

As shown in Figure 1, the opposite surface of the belt 10, the backside 12, is a surface passing over papermaking machinery used in the papermaking process, such as papermaking belt return rollers 19a-19c, 19e and 19f and vacuum catch 24a and suction box 24, as well as other underpressures in contact with it. Figure 1 shows that the side of the belt 10 called the back side 12 is referred to by this name, although it may occasionally point away from the machinery used in the papermaking process (such as at the papermaking belt return roll 19d). However, the backing side is separable from the paper contacting side 11 because the backing side 12 never comes into contact with the paper web during the papermaking process. The back side 12 of the papermaking belt according to the present invention may also be referred to herein as the bottom surface of the belt. It can also be called the tread of the belt because it is the surface of the belt that is subjected to the abrasion effect when it repeatedly passes over the papermaking machine during the papermaking process. It is to be understood that although the backside 10 of the belt 12 may be referred to as the bottom surface, the backside 12 may be such orientation that it extends upwardly paluuII path in a papermaking machine when the belt 10 is in the form of an endless belt. As shown in Figures 3 and 4, the back side 12 of the belt 10 may be formed entirely from the second surface 35 of the grid 32. Alternatively, the backsheet 12 may be formed entirely on the machine side 52 of the reinforcing structure 33 or may be formed in part on the second surface 35 of the lattice 32 and in part on the machine side of the reinforcing structure 33 52. It is this backsheet 12 and methods of of primary importance in this invention.

Figures 2-4 show a reinforcing structure 33, one of the main elements of a papermaking belt 10 according to the present invention. The reinforcing structure 33 reinforces the resin grid 15 and has a suitable open projection surface to allow the vacuum dewatering machinery used in the papermaking process to adequately perform its function of removing water from the partially formed paper webs and allowing water removed from the paper web to pass through the papermaking belt 10. The reinforcing structure 33 can take any of a variety of forms. The reinforcing structure 33 may comprise a woven element (sometimes also referred to herein as a woven fabric), a nonwoven element, a wire, a mesh (e.g. thermoplastic mesh material), a gauze or strip or sheet (made of metal, plastic or other suitable material) stamped or drilled numerous holes, provided that the that the reinforcing structure 33 sufficiently reinforces the lattice 32 and has a sufficient open projection surface for the purposes defined above. The reinforcing structure 33 preferably comprises a woven element (or more specifically a porous woven element), such as the element shown in Figures 2-4.

As shown in Figures 2-4, the reinforcing structure

33 generally comprises a reinforcing component 40 and a plurality of pores (i.e., small holes) 39. The reinforcing component 40 is a portion of the reinforcing structure other than the pores 39. That is, the reinforcing component 40 is an integral part of the reinforcing structure 33. The reinforcing component 40 consists of one or more structural components 40a. As used herein, the term structural components refers to individual structural elements that form a reinforcing structure 33.

The pores 39 allow fluids (such as water removed from the paper web) to pass through the belt 10. The pores 39 form one of the aperture groups of the papermaking belt 10. Figure 2 shows that the pores 39 may form a pattern on the reinforcing structure 33. However, the pattern formed by the pores 39 must be distinguished from the prefabricated pattern formed by the channel openings, such as the first channel openings 42. Figure 2 shows that the size of each pore 39 is typically only a fraction of the size of the channel opening 42, but the opposite ratio is also possible.

As shown in Figures 3 and 4, the reinforcing structure 33 has two sides. These are the paper-facing side (or paper support side), designated generally by the numeral 51 and faces the fiber webs, which is to be dewatered, and the paper-facing side of the opposing side of the machine-facing side (or in contact with the roller side), designated generally numbered 52 and directed toward the papermaking machinery. The sides of the reinforcing structure 33, referred to herein as the paper-facing side 51 and the machine-facing side 52, are referred to by these names, although short periods may occur during each revolution of the papermaking belt 10, in which case they may be in the opposite orientation. In addition, these names are consistently used on the respective sides of the reinforcing structure 33 even before the reinforcing structure 33 is stored in the papermaking belt 10 of the present invention and the belt 10 is installed in the paper machine. Thus, the side of the reinforcing structure 33, called the machine-facing side 52 in the method of making the papermaking belt 10 of the present invention, is the side that is generally oriented toward the papermaking machine when the finished belt is mounted on the papermaking machine. The side 51 facing the paper is always on the opposite side to the side 52 facing the machine. As shown in Figures 3 and 4, the reinforcing structure 33 is placed between the first surface 34 of the lattice 32 and at least a portion of the second surface 35 of the lattice 32.

Figures 2-4 show that when the reinforcing structure 33 comprises a woven element, the individual yarns woven together into a woven element form the structural components 40a of the reinforcing structure 33. If the reinforcing structure 33 comprised a nonwoven element, the individual fibers that make up the nonwoven element would form the structural components 40a. In either case, there are a plurality of structural components, so that all of these structural components 40a together form a reinforcing component 40. If the reinforcing structure 33 is on the other hand a plate in which a plurality of holes are stamped, there is only one structural component 40a (plate) and it forms a reinforcing component 40.

The structural components 40a of the woven reinforcing structure comprise yarns, filaments, filaments or fibers. It is to be understood that the terms yarns, threads, filaments, and filaments are synonymous when used to describe the structural components 40a of a woven reinforcing structure. It is also to be understood that the above terms (yarns, threads, etc.) include not only monofilament elements but also multifilament elements.

When the reinforcing structure 33 comprises a woven element, as shown in Figures 2-4, some of the individual structural components are machine direction warp yarns, generally designated 53, and some transverse weft yarns, generally designated 54. As used herein, the terms machine direction warp, warp, and carrier warp are synonymous and refer to yarns that are generally oriented in the machine direction when the papermaking belt 10 of the present invention is mounted on a paper machine. As used herein, the terms transverse weft, weft, wire weft, and warp balancing weft are synonymous and refer to yarns that are generally oriented in the transverse direction when the papermaking belt 10 of the present invention is mounted on a paper machine.

In papermaking, the term machine direction (MD) means a direction parallel to the passage of a paper web through the apparatus. The cross direction (CD) is perpendicular to the machine direction. These directions are indicated by the arrows in Figure 2 and a few subsequent figures.

The definitions of warp and weft yarns used herein may sometimes differ from the definitions of said terms when describing the orientation of the yarns of a woven fabric when weaving a fabric in a weaving machine. In the field of weaving, whether a yarn is called a warp or weft yarn depends in part on whether the fabric is an endless woven fabric that does not need to be looped to form an endless belt, or whether it is a planar woven fabric that must be seamed to form an endless belt. In the case of an endless woven fabric that does not need to be stitched into a loop, the yarns, called warp yarns in the weaving machine, run transversely in the paper machine. If, instead, the fabric is woven into a planar and then seamed into a loop, the yarns, called warp yarns in the weaving machine, run in the machine direction on the paper machine. As used herein, the terms warp yarns and weft yarns refer to the orientation of the yarns with the fabric in place on the paper machine and not the orientation when weaving the fabric into the weaving machine. Thus, warp yarns mean machine direction warp yarns and weft yarns transverse weft yarns when the papermaking belt of the present invention is mounted on a paper machine.

Figures 2-4 also show that in the woven reinforcing structure 33, some of the yarns intersect and form knees 105 in the fabric. As used herein, the knee is either a portion of the weft yarn passing over the warp yarn or a portion of the warp yarn passing over the weft yarn on either paper of the reinforcing structure 33. per per side of the machine-facing side 51 or 52) in a plane. Knuckles, which are the reinforcing structure 33 toward the paper-facing side 51 (i.e., paper side knuckles) is designated as 105_:. Knuckles, which are the reinforcing structure 33 of the machine 52 toward the side (i.e., backside knuckles) is designated as 105₂. These knees 105 can be further classified as either warp knees or weft knees and use these designations.

As used herein, the term warp knees means knees formed by a portion of a warp yarn that passes over the weft yarn. A few such warp knees are used as 105a in the alternative embodiment of the papermaking belt 10 of the present invention shown in Figure 5 (which includes a single layer reinforcing structure 33). As shown by the cross section in Fig. 5B, the warp knees 105a may be either on the paper side 51 of the reinforcing structure 33 or on its machine side 52. The warp knees on the paper side 51 of the reinforcing structure 33 are denoted 105a! the warp knees on side 52 are designated 105a₂.

The knees formed by the portion of the weft yarn that passes over the warp yarn are referred to herein as weft knees. A few such tissue knees are shown in Figures 2 and 3 as 105b. Figure 3 shows that the weft knees, as well as the warp knees, can either be on the paper side 51 of the reinforcing structure 33, such as the weft knee 1051, or on the machine side 52 of the reinforcing structure 33, such as the weft knee 105b.₂.

Many types of woven elements are suitable for use as a reinforcing structure 33 in the papermaking belt 10 of the present invention. Suitable woven elements include porous single-layer woven elements (having one group of threads in each direction and numerous openings therebetween), such as the reinforcing structure shown in Figures 5, 5A and 5B, multilayer woven elements (woven fabrics having more than one group of threads in at least one other). direction), and fabrics with a few layers, each comprising interwoven strands.

Multilayer woven fabrics are preferred as reinforcing structures because they can extend the life of a composite papermaking belt. As used herein, a composite papermaking belt means a belt consisting of a lattice and a reinforcing structure. The papermaking belt 10 is subjected to considerable stress in the machine direction due to the fact that the belt 10 repeatedly passes over the papermaking machine in the machine direction, and also because heat is transferred to the belt from the drying equipment used in the papermaking process. Such heat and stress expose the papermaking belt to stretching. If the papermaking belt 10 stretches out of shape, its ability to fulfill its function of transporting paper through the papermaking process is impaired up to the point of unusability.

Il

In order for the multilayer woven element to be suitable for use as a reinforcing structure in the papermaking belt of the present invention, it preferably has some type of structure that reinforces its machine direction yarns 53 to reduce the above-mentioned stretching problem. In other words, the multilayer fabric must have improved fabric stability in the machine direction. The arrangement of the warp yarns 53 should be such that any further reinforcement of the warp yarns does not reduce the projection of the open surface of the reinforcing structure.

As used herein, surface projection refers to the area formed when projecting the points delimiting that element to a plane. More specifically, it is to be understood that these points are projected in a direction called the z-direction. The projection of the open surface of the reinforcing structure is denoted by A_o in Figure 12 of the accompanying drawings. As used herein, the term open surface projection means the projection of a surface defined by the projection of all surfaces defined by the pores 39 of the reinforcing structure 33 in the z direction. That is, the projection A of the open surface of the reinforcing structure 33_o is a surface seen when the reinforcing structure is viewed in a direction perpendicular to either side of the reinforcing structure through the pores 39 forming straight lines of sight passing through the fabric.

Throughout this description, reference is made to the x, y, and z directions. As used herein, the directions x, y, and z are the directions of a rectangular coordinate system relative to the papermaking belt (or portions thereof) of the present invention. In the rectangular coordinate system described herein, the back side 12 of the belt is in a plane formed by the x- and y-axes, the x-axis is the transverse direction, the y-axis is the machine direction, and the z-axis is perpendicular to the plane defined by the x- and y-axes. As used herein, the z-direction means directions parallel to the z-axis and perpendicular to the x- and y-axes. These directions are best seen in Figures 2-4.

The projection of the open surface of the reinforcing structure 33 should preferably be such that the reinforcing structure

33 is highly permeable (for fluids such as air and water). The term highly permeable means that the air permeability of the reinforcing structure should be in the range of approximately 240 - 430 m³/ min 1 m²per area with a pressure difference of 100 Pa. The air permeability of the reinforcing structure 33 is of great importance because it, together with the lattice, provides the air permeability of the composite belt. The air permeability of the composite belt should be approximately in the range of 90 to 180 m³/ Min. The preferred air permeability of the composite belt is about 150 m³/ Min.

In order for both the reinforcing structure 33 and the composite belt to be sufficiently permeable, it is preferred that the projection A of the open surface of the reinforcing structure_o not less than about 30%, and most preferably the projection of the open surface is not less than about 40-50%.

As shown in Figures 2-4, one preferred reinforcing structure 33 is a multilayer woven element having a single layer yarn system with yarns running in the first direction and a multilayer yarn system having yarns running in the second direction, which direction is parallel to the normal of the first direction. In the preferred reinforcing structure shown in Figures 2-4, the first direction is the transverse direction. The simple layer of yarns running in the first direction comprises weft yarns 54. In the reinforcing structure shown in Figures 2-4, the multilayer yarn system is in the machine direction (i.e., the direction in which the fabric travels in the paper machine). The multilayer yarn system comprises a first warp layer C and a second warp layer D. Each of the warp layers C and D comprises a plurality of warp 35 yarns 53. Although the most preferred fabrics for use as a reinforcing structure have a plurality of machine direction warp yarn layers, the present invention can also be practiced using a fabric having a plurality of thread layers in the transverse direction. However, fabrics with multiple layers of warp yarn running in the machine direction are preferred because the additional threads travel in a direction that is usually subjected to the greatest stresses.

As shown in Fig. 3, the preferred multilayer reinforcing structure 33 has warp yarns 53 arranged vertically directly on top of each other. Vertically superimposed warp yarns 53 improve the stability of the composite belt 10 in the machine or process direction. Arranging the warp yarns on top of each other also results in a suitable open surface projection so that the belt 10 can be used in various types of papermaking processes, including papermaking processes in which blow-drying is performed. The weft yarns 54 are preferably arranged to maintain and stabilize the vertical overlap of the warp yarns 53. The weft yarns 54 may also be placed vertically on top of each other, or they may be in some other relationship to each other. Numerous variations of such arrangements are possible.

Figures 6-11 show the tissue structure of the particularly preferred multilayer reinforcing structure 33 shown in Figures 2-4. As used herein, tissue structure refers to the technical design of a tissue. The multilayer fabric is shown in Figures 6-11 without the surrounding lattice for clarity. Although the same fabric is shown in the figures

2 - 4 as composite elements in a papermaking belt (i.e.

as a reinforcing structure for reinforcing the grid 32 of the papermaking belt 10 according to the present invention), the fabric shown is also suitable for use as such as a papermaking belt without such a grid. However, the multilayer fabric shown in Figs. 32 is preferably used in conjunction with some type of lattice.

As shown in Figs. 6 to 11, the first warp layer C of warp yarns 53 generally runs in the machine direction on the paper-facing side 51 of the fabric. The individual warp yarns in the first warp layer C are numbered 53a, 53b, 53c and 53d. The second layer D of warp yarns 53 runs in the machine direction on the machine side 52 of the fabric. The individual warp fabrics in the second warp layer D are numbered 53e, 53f, 53g and 53h over the fabric. As best seen in Figures 8 to 11, the individual yarns of the first warp layer C and the second warp layer D define pairs E, F, G and H formed by overlapping warp yarns. The individual yarns defining the pairs E, F, G and H formed by the overlapping warp yarns are generally arranged vertically one on top of the other. The numbering of the pairs E, F, G and H formed by these overlapping warp yarns also continues repeatedly over the fabric. Figures 8-11 show that the individual warp yarns 53a and 53e define a pair E of overlapping warp yarns, the warp yarns 53b and 53f define a pair F of overlapping warp yarns, the warp yarns 53c and 53g define a pair F of the overlapping warp yarns and the warp yarns 53d of the warp yarns B. As shown in Fig. 6 and Figs. 8-11, the parallel pairs of overlapping warp yarns are spaced apart from each other so as to provide the desired open surface of the fabric.

As shown in Fig. 6, because the warp yarns 53 are superimposed, the effective density of the warp yarns 52 (i.e., the yarn density of the warp yarns) is doubled without decreasing the open surface of the reinforcing structure 33. As used herein, yarn density means a numerical value equal to the number of yarns per unit width of fabric (in which inch is usually used as an inch) multiplied by the diameter of the yarn (which is usually also measured in inches). The yarn density can be specified in more detail for warp yarns of the fabric (i.e., warp yarn density) or weft yarns of the fabric (i.e., weft yarn density).

A weft yarn such as weft yarn 54a in Fig. 8, 54b in Fig. 9, 54c in Fig. 10 and 54d in Fig. 11 is woven together with warp yarns 53a to 53h in the first and second warp layers. The weft yarns bind the individual warp yarns in the first and second warp yarn layers into pairs formed by overlapping yarns and prevent the warp yarns 53a to 53h from moving laterally and reducing the open surface of the fabric. These weft yarns 54a, 54b, 54c and 54d are also repeatedly numbered over the fabric. The weft yarns 54 are woven together with pairs of overlapping warp yarns to form a special fabric structure (or more specifically, a warp balancing fabric structure). The weft yarns 54 hold the warp yarns on top of each other and generally vertically aligned.

The special fabric pattern formed by the warp yarns 53 and the weft yarns 54 in the fabric shown in Figures 6-11 is known as a four-viral repeating structure. As used herein, a weft refers to the number of unique structures that either a warp yarn or a weft yarn forms with the yarns to be woven with it before repetition occurs (i.e., a four-weft structure would be a structure that is repeated after each group of four yarns).

The particular structure in which the warp yarns 53 are woven is best seen in Figures 6 and 7. As shown in Figures 6 and 7, the first warp yarns of the first warp layer C (such as the warp yarn 53b shown in Figure 7) weave repeatedly over three woven yarns and under one woven yarn. the weave pattern. As used herein, the term apply to a fabric means to place a weft yarn between separated warp yarns. The second warp yarns of the second warp layer D (such as the warp yarn 53f shown in Fig. 7) repeatedly pass over one weft yarn introduced into the fabric and under the three weft yarns introduced into the fabric in the fabric structure.

The particular structure in which the weft yarns 54 are woven is best seen in Figures 6 and 8-11. The weft yarns 54 are woven around the overlapping warps following a repetitive pattern in which the weft yarn (such as the weft yarn 54a in Fig. 8) first passes over a first pair of overlapping warp yarns E, a second pair of overlapping warp yarns F warp yarns, a third between the warp yarns of the pair H formed. That is, each weft yarn 54 passes over and under every other pair of overlapping warp yarns and between these pairs of overlapping warp yarns formed by each other pair of overlapping warp yarns.

As shown in Figs. 6 and 8 to 11, adjacent weft yarns are woven around the warp yarns 53 in the same manner. As shown in Figure 9, adjacent weft yarns, such as weft yarn 54b, move by one pair of warp yarns relative to the position of the first weft yarn. Thus, the adjacent or second weft yarn passes between the warp yarns of the first pair of overlapping warp yarns, the second pair of overlapping warp yarns

II over, between the warp yarns of the third pair of overlapping warp yarns and under the fourth pair of warp yarns of the overlapping warp yarns. As shown in Figs. 10 and 11, the third warp yarn 54c similarly moves one pair of warp yarns relative to the second weft yarn, and the fourth warp yarn 54d moves one pair of warp yarns relative to the third weft yarn, respectively. This pattern is repeated every fourth weft yarn. As shown in Fig. 6, this provides a woven structure in which the intersections 55 formed by the weft fabrics 54 pass stepwise across the warp yarns in the weft direction.

One variation of the fabric structure shown above can be obtained by interchanging the weft yarn 54c shown in Fig. 10 and the weft yarn 54d shown in Fig. 11. This results in a truncated stepped pattern of weft intersections 55 in the weft direction. In this truncated figure, the first two intersections 55 are on the diagonal. However, the third intersection point 55 moves over the third warp yarn to the fourth warp yarn, and the fourth intersection point 55 moves over the third warp yarn to the fourth warp yarn, and then the intersection point 55 moves back parallel to the diagonal yarn to the third warp yarn. This weave structure also keeps the warp yarns in the pairs of overlapping warp yarns properly arranged. However, in this fabric structure variation, the two warp yarns pass together between two parallel weft yarns introduced into the fabric. The fabric structure first described does not have two weft yarns inserted into the fabric, between which the warp yarns pass simultaneously, which gives the fabric structure a slightly better balance.

Various combinations of yarn materials, cross-sectional dimensions, and cross-sectional shapes can be used in this preferred fabric. Yarn material36

Iin, the dimensions of the cross-section and the shape of the cross-section are determined by the particular use of the fabric.

Although the structural materials of warp yarns and weft yarns may vary, the yarn material should be such that the yarns have the ability to reinforce the resin lattice and withstand stresses as well as repeated heating and cooling without stretching too much. Suitable materials from which yarns can be formed include polyester, polyamide, highly heat resistant materials such as KEVLAR and NOMEX grades, and any other materials known to be used in papermaking fabrics. However, the preferred yarn material is polyester. The structural material of the yarns in different layers and yarn systems may vary, with the yarns of one layer or yarn system being formed of one material and the yarns of the other layers or yarn systems of different materials. However, all the yarns of the different layers and yarn systems are preferably made of substantially the same material.

Any suitable cross-sectional dimensions (or sizes) of yarns may be used, as long as the flow of air and water through the channels 36 is not significantly impaired during paper web processing and the integrity of the papermaking belt 10 as a whole is maintained. Yarns with the same cross-sectional dimensions can be used in all layers or yarn systems, or the size of the yarns can be different in different layers and yarn systems. For example, if yarns with a circular cross-section are used, the yarns of the warp systems C and D may have one diameter and the yarns of the weft system may be larger or smaller in diameter. If larger diameter weft yarns are used, the weft yarns are stiffer and cause more curl in the warp yarns. Other variations include those with warp system C and weft system 54 yarns

II are similar and the yarns of the warp system D are different. Likewise, the yarns of the warp system D and the yarns of the weft system may be similar and the yarns of the warp system C may be different. Alternatively, the yarns may be different in warp system C, warp system D, and weft system each. In the case of yarns of circular cross-section, the preferred diameter range of the yarns is about 0.10 to 0.30 mm. The most preferred diameters are about 0.22 mm for warp yarns 53 and about 0.28 mm for weft yarns 54. Depending on the application, larger diameter yarns can also be used.

Yarns of any suitable cross-sectional shape may be used as long as the yarns do not interfere with the flow of fluids through the channels 36 during web processing and the integrity of the papermaking belt 10 as a whole is maintained. Suitable cross-sections include circular, oval, square and rectangular cross-sections. The cross-sectional shapes of the yarns in the different layers and yarn systems may also vary between the layers and the yarn systems. However, both the warp yarns 53 and the weft yarns 54 preferably have a circular cross-section.

the reinforcing structure 33 of the present invention defines several projected areas which are useful in kuvattaesa 38 in the position of the passageways 37 and surface texture irregularities 32 of the second surface 35 of the framework backside network 35a. As shown in Figures 12-18, the reinforcing structure 33 defines at least the following surface projections: projections of the pore surfaces; a previously defined open surface projection (which is the sum of the projections of all the pore surfaces of the reinforcing structure); projections of structural component surfaces; the projection of the reinforcing surface (which is the sum of the projections of all the structural component surfaces of the reinforcing structure); projected warp areas (and loimipinnan kokonaisprojektio) to polvekepin38 of the projections and the machine side polvekepintojen projections. In addition, when there are several warp or weft layers or the like, there may also be projections of the warp yarn surfaces of the first warp layer and the second warp layer, etc.

The projections of the pore surfaces are indicated in Fig. 12 by the notation Ap₃. As used herein, the projections of the pore surfaces refer to the individual projections of the surfaces defined by the projections of the pores 39 of the reinforcing structure 33. That is, when the reinforcing structure 33 is viewed from a direction perpendicular to either side of the reinforcing structure, each pore 39 forms straight lines of sight passing through the reinforcing structure, which form projections of the pore surfaces Ap._t.

Projection of the structural component surface A_sc is shown in Fig. 13. As used herein, the projection of a structural component surface means the surface determined by the projection of the individual structural component 40a of the reinforcing structure 33. As used herein, projections of structural component surfaces means a surface defined by the projection of more than one, but not all, structural component 40a of the reinforcing structure 33.

A portion of the projection A „of the reinforcing surface is shown in Fig. 13. As used herein, the term projection of the reinforcing surface means a surface defined by the projection of the reinforcing component 40. As shown in Figs. 12 and 13, the projection A of the reinforcing surface_R is the projection A of the open surface of the reinforcing component_o opposite; it is that part of the reinforcing structure 33 which cuts the lines of sight. Projection of the reinforcing surface A_R is complementary to the open surface projection A_o, because together they form the projection of the entire surface of the reinforcing structure 33.

Figures 14 and 15 show projections of the warp surfaces. As used herein, warp surface projection means a surface defined by the projection of individual warp yarns 53 of the reinforcing structure 33. In Fig. 15, the projections A 1 of the warp surfaces are shown as areas shaded by slashes between the dashed lines. The dotted lines could also extend to the paper-reinforcing structure above the side 51. However, generally speaking, this invention is not concerned with passageways and surface texture irregularities which are the reinforcing structure 33 toward the paper above the plane of the side 51. When the position of a passageway or surface texture irregularity is described herein with reference to a projected area, the passageway or irregularity lies therefore in per 33 paper side of the reinforcing structure 51 and between the plane defined by the backside 10 of the belt. When it is said that the path or surface texture irregularity is within the projections of the warp surfaces shown in Figures 14 and 15, it may be any point within the areas shaded in Figure 14 or shaded by slashes in Figure 15. In addition to the projection of each warp defined by a single warp, there is a total warp projection A_UPO, comprising the sum of the projections of the individual warp surfaces over the entire fabric.

Figures 16 and 17 show projections of tissue surfaces A_wt. As used herein, tissue surface projection A_wt means a surface defined by the projection of the individual weft yarns 53 of the reinforcing structure 33. In addition to the projection A ^ of the hexagon surface, there is a total projection A „of the weft surface._to(part of which is shown in Figures 16 and 17) comprising projections A of individual tissue surfaces_wt amount over the entire area of ​​the reinforcing structure.

As used herein, the projection of the knee surface of the reinforcing structure 33 means the surface defined by the projection of one knee 105 of the woven reinforcing structure. As shown in Figs. 18A to 18C, the knee surface projection A_K is that part of the reinforcing structure 33 in which the warp yarn and the weft yarn overlap and which cut off the aiming lines passing through the reinforcing structure 33. In addition, the projections of the knee surfaces can be classified as projections of the warp knee surfaces A_kWp (projection surface formed by a warp yarn passing over the weft yarn) or as projections of the weft knee surfaces A_Kwt (projection surface formed by a weft yarn passing over a warp yarn). Warp knee surface projections_kWp and projections of spawning knee surfaces A_Kwt can be further classified on the paper side (that is, paper-facing side) of the projected loimipolvekepintojen_Kwpl or as projections of tissue tissue knee surfaces A_Kwtl and the machine-facing side (or machine side) of a projected loimipolvekepintojen_Kwp2 or as projections of tissue tissue knee surfaces A_Kwt2 (depending on which side of the fabric the knees are formed).

The second main element of the papermaking belt 10 of the present invention is a grid 32. Figures 2-4 show general characteristics of the grid 32. In a preferred embodiment of the present invention, the lattice 32 is formed by treating a generally liquid mass of material such that the material in solid form surrounds at least partially the reinforcing structure 33 such that the reinforcing structure 33 is positioned between the first surface 34 and at least a portion of the lattice 32 surface 35. In addition, the material must be treated so that the grid 32 has a plurality of channels 36 extending between the first surface 34 and the second surface 35 of the grid 32. The material must be handled in such a manner that the first surface is formed by the paper side network 34a which surrounds and defines the framework 32 in the first surface 34 of the channels 36 holes. Further, the material must be manipulated so that the second surface 32 of the grid 35 is the backside network 35a of the channels 36 of contrasting passageways 37 that provide surface texture irregularities 38 in the backside network 35a.

Il

The mass of material treated to form the grid 32 may be any suitable material, including thermoplastic and photosensitive resins, but the preferred material for use in forming the grid 32 of this invention is a liquid photosensitive polymeric resin. The selected material can likewise be treated in a variety of ways to form the desired lattice 32, including mechanical stamping or drilling, curing the materials by treating them with different temperatures or energy sources, or using a laser to cut channels in the material. The method of processing the material forming the grid 32 will, of course, depend on the selected material and the properties of the grid 32 to be formed from the mass of material. The preferred method for treating the photosensitive resin is to control the exposure of the liquid photosensitive resin to light having an activating wavelength.

the papermaking belt of the present invention, 10 sides (with ie. the paper described above kosketukses20 At the side 11 and the backside 12) and the framework 32. The relationship between the surfaces is best seen in Figures 32 a first surface 3 and 4. The grid 34 is preferably formed to be in contact with the papermaking belt 10 of the paper side 11 . This relationship generally exists useim25 in embodiments of the present invention, since the reinforcing structure 34 is positioned between three and at least a portion of the first surface 32 of the framework 32 to the second surface of the grid 35. In other words, the first surface 32 of the truss 34 generally covers the paper 33 toward the side of the reinforcing structure 51.

However, the second surface 35 of the grid 32 of the papermaking belt 10 of the present invention may not always form the back side 12 of the papermaking belt 10. Because the reinforcing structure 33 is positioned between the first surface 34 and at least a portion of the second surface 35, the second surface of the grid 32 may either completely cover the reinforcing structure 33 or cover only parts of the reinforcing structure 33 and be completely in the pores 39 of the reinforcing structure 33. In the former case, the second surface 35 of the grid 32 and the back side 12 of the papermaking belt 10 are the same thing. In the second case, the back side 12 of the papermaking belt 10 consists partly of the second surface 35 of the lattice and partly of the exposed part of the reinforcing structure. In the third case, the rear side 12 of the papermaking belt 10 also consists partly of the second surface 35 of the grid 32 and partly of the reinforcing structure 33, but the machine-facing side 52 of the reinforcing structure 33 is completely exposed on the rear side 12 of the papermaking belt 10.

Figure 2 shows that the first surface 34 of the grid 32 (and the paper-contacting side 11 of the papermaking belt 10) consists of a portion of the network designated 32a. As used herein, the term network refers to portions of the grid 32 that surround the channels 36 and define a network-like pattern. In other words, the network 32a is an integral part of the grid 32. As shown in the enlarged photographs of the papermaking belt 10 of the present invention, Figs. 36A and 36B, the grid 32a has two mesh surfaces 34a and 35a. As used herein, a network surface means one of the surfaces of a network 32a surrounding channels 36. These network surfaces are also referred to herein as the knees of the lattice 32. However, the knees of the lattice 32 should be distinguished from the previously described knees formed by the wires of the reinforcing structure 33. The term network surface is also used in the Trokhan and Johnson patents, which are incorporated herein by reference. As used herein, the term network, however, the surface modified by specifying whether the network surface of the paper side network surface or the backside network surface.

il

The term paper side network surface (or for short, the paper side network) refers to a grid 32 of upper or first surface 34 of the fixed part of the grid. Thus, the surface of the grid, which is called verkostopinnaksi herein by reference in those patents generally corresponds to the paper side network surface in the present specification. The paper side network surface is represented by reference numeral 34a in the drawings.

The term backside network surface, (or the backside network) refers to a surface 32 of the fixed part 35 of the framework 32 in the second grid. The backside network surface is represented in the drawings by reference number 35a.

As 2-4 shown in the figures, 32 of first surface 34 includes both p aperipuolen network surface 34a and the first conduit openings 42. The first conduit openings 42 of the conduits 36 holes the grid in the first 32 on the surface 32 of the second surface 34. The grid 35 comprises both the backside network surface 35a and the second channel openings 43. The second channel openings 43 are openings in the channels 36 on the second surface 35 of the grid 32. The grid 32 in the paper side network surface 34a and the first surface 34 of the first channel-air openings 42 are described herein often complementary, because together they respectively comprise one entire surface of the grid. For the same reason, the backside network surface 35a and second conduit openings 43 are described herein as complementary.

As shown in Figure 2, the paper side network 34a is macroscopically monoplanar, patterned, and continuous. This allows a uniform pattern to be formed in the paper web during processing. Macroscopically monoplanar means that when a part of the papermaking belt 10 of the paper side 11 disposed in a plane, the paper side network 34a is essentially in one plane. It is said to be substantially single-level in order to understand the fact that deviations from absolute flatness are tolerable, but not preferred, as long as the deviations are not so significant as to adversely affect the performance of the product formed by the papermaking belt 10. The paper side network 34a is said to be continuous, because the lines formed by the network on the paper side network surface 34a must form at least one essentially unbroken net-like pattern. The pattern is said to be substantially continuous to understand that pattern breaks are tolerable, but not preferred, as long as the breaks are not so substantial as to adversely affect the performance of the product formed by the papermaking belt 10.

Channels (i.e., guide channels) 36 extending from the first surface 34 of the grid 32 to the second surface 35 of the grid 32 are shown in Figures 2-4. Each channel 36 defines certain features, including a channel portion, or cavity, commonly referred to as 41; a mouth or channel opening (also known as large pores), such as a first channel opening 42 formed on the first surface 34 of the lattice 32; a mouth or channel opening, such as a second channel opening 43 formed generally on the second surface 35 of the grid 32, and channel walls, generally designated 44, defining the dimensions of the channels 36 within the interior of the grid 32. (The inner portion of the lattice is a portion of the lattice 32 between the first and second surfaces 34 and 35.) As shown in Figures 2-4, the walls 44 of the channels 36 form the inner walls 44a of the lattice 32. The inner walls 44a of the grid 32 are surfaces of the grid 32 that coincide with the walls 44 of the channels 36. That is, the walls 44 of the channels 36 have the same, i.e., congruent, boundaries with the inner walls 44a of the lattice 32. The second channel openings 43 are generally described as being formed on the second surface 35 of the lattice 32, because if one or more passageways 37 intersect the second channel opening 43, at least a portion of the second channel opening 43 may move with it.

II in that it is in fact between the first surface 34 of the grid 32 and the surrounding parts of the second surface 35 of the grid 32. That is, portions of the second channel openings 43 may be inward (toward the center of the belt) from a plane defined by portions adjacent the second surface 35 of the truss 32.

Figure 2 shows that the first channel openings 42 in the first surface 34 of the grid 2 are uniform and of a certain shape. The 32 second surface 35 of the framework second conduit openings 43 are the same shape basically as the first conduit openings 42. As shown in Figure 37B shows the framework 32 in the backside network 35a appear in the passageways and surface texture irregularities can cause the second conduit openings distorted and very irregular in shape. This distortion is not particularly problematic in the present invention, because the backside network 35a which surrounds the second conduit openings 43 does not contact with the paper web during formation and press the pattern.

Although there is an unlimited variety of possible shapes for the openings 42 and 43 of the channels 36, certain loose instructions may be given for selecting the particular shape of the channel opening. These instructions are set forth in U.S. Patent 4,528,239 (Deflection Member, Paul J. Trokham, July 9, 1985), column 5, line 34, column 10, line 35, which is incorporated herein by reference.

The shape and order of the channels shown in Figure 2 are together in a particularly preferred form. The shape of the channel openings 42 and 43 shown in these figures is referred to herein as conforming to the linear Idaho pattern. As shown in Figure 2, the channels in the shape of a linear Idaho pattern are roughly in the shape of modified transformers. The shape of the channels 36 is said to resemble a modified parabola, because in this top view, each channel 36 has four sides, with the sides on opposite sides being parallel, the angle between the parallel sides not being a right angle and the corners between the parallel sides being rounded. Thus, channel openings in the shape of a linear Idaho pattern can also be described as round-angled parallelepipeds.

The structural details of these linear Idaho patterned channels 36 are shown in Figure 19.

Fig. 19 shows only a part of the grid 32 of the papermaking belt 10, showing a repeating pattern formed by the channels 36. In addition, for reasons of clarity is shown only the paper side network surface 34a on all but one channel. This particular shape of the channels 36 is obtained as described below. However, as should be obvious, it is possible to change the order of the steps and achieve the same result. It is also apparent that the dots, lines, and circles used to provide the shape of the channels are not actually visible in the channels 36 formed by the procedure described below (except where they form the walls 44 of the channels 36).

To obtain a geometric shape according to the linear Idaho pattern, two points P are first selected_x and

P₂, which are at a given distance d_x one another. These two points P_x and P₂ the connecting line is called the channel axis in the machine direction, i.e. the longitudinal axis A_L. These two points P_x and P₂ distance between (equal to the longitudinal axis A_L length) is preselected. A circle with a certain radius R is drawn at each of these 30 points_x. Next, draw a straight line A_T, which is perpendicular to the longitudinal axis A of the channel_L against. This next straight A_Tis drawn along the longitudinal axis A_L across so that it bisects the longitudinal axis A_L. Then two points P are placed₃ and

P₄ to another line A_T equidistant from the length47 from the axis A_L. Also points P₃ and P₄ the distance between is selected in advance. Points P₃ and P₄ connecting line A_T is called the channel axis in the transverse direction, i.e. the transverse axis. To each of the points P₃ and P₄ draw a circle with a certain radius R₂. Although the latter radius R₂ need not be equal to the radius R of the previously drawn circle₃, in the preferred figure R shown in Fig. 19_xis equal to R₂. As a final step, the tangents L are drawn_lz L₂, L₃ and L₄ between parts of previously drawn circles. The tangents are drawn in such a way that they are tangential to those parts of the circles which are furthest from the longitudinal axis A_L and the transverse axis A_T the point of intersection. A line running around the circumference of the pattern thus described forms the walls 44 of the linear Idaho patterned channel 36. As shown in Figure 19, the sides of the first channel openings are denoted 45a, 45b, 45c and 45d and the rounded corners between adjacent sides are denoted by 46. the respective sides of the channel openings 43 are denoted 45e, 45f, 45g and 45h. The corresponding corners of the second channel openings 43 are used to denote 46a.

Other suitable shapes for the channels in the grid 32 of the papermaking belt 10 of the present invention include, but are not limited to, the modified hexagon described in the Trokham and Johnson patents, which are incorporated herein by reference, and the knot or blue curve pattern shown in Figure 20.

Regardless of the shape of the channel openings, whether in the preferred linear Idaho pattern or some other form, the number of channels 36 per defined belt area and the relative space occupied by the channel openings in the grid 32 of the papermaking belt 10 should be within specified limits.

The number of channels 36 in the grid 32 is generally expressed as the number of channels per square inch of the total area of ​​the grid 32. As used herein, the term lattice of the total surface area refers to either the amount of the paper side network surface 34a of the surface area and the first conduit openings 42 occupied by the complementary surface area or the sum of the backside network surface 35a area and second openings 43 occupied by the complementary surface area. The number of channels 36 in the grid 32 should preferably be about 10 to 1,000 per square inch.

The relative amount of space occupied by the channel openings is usually expressed here as a percentage of the total area of ​​the grid 32. It is also common in this specification to express the relative space occupied by the complementary network surfaces 34a and 35a of the lattice as a percentage of the total area of ​​the lattice 32. The paper side network surface 34a and the backside 35 of space occupied by the network surface is referred to herein generally knuckle areas 32 of the respective faces of the grid. These knee areas are indicated by A in Figures 19A and 19B_N1 and A, respectively_N2. The paper side knuckle area (or first surface knuckle area) A ,,! (Hatched in Figure 19A) has a paper side network surface 35a on the projection plane in the z-direction. Background knee area (i.e., other surface knee area)_N2 (Shaded in Figure 19B) is a backside network surface 35A of the projection plane in the z-direction. The relative space occupied by the channel openings can be derived from the space occupied by the knee areas of the lattice 32. Since the area occupied by the channel openings and the area occupied by the corresponding network surfaces are complementary, the sum of these two percentages is 100%. If either the knee areas or the relative space occupied by the channel openings are known, the complementary area can be calculated by subtracting a known percentage from 100%.

The relative space occupied by the first channel openings 42 in the first surface 34 of the grid 32 is preferably about 30 to 80% of the total surface area of ​​the grid 32. That is, the first surface 34 of the lattice 32 contains about 20 to 70% of the knee area. The relative space occupied by the second channel openings 43 in the second surface 35 of the grid 32 is preferably about 30 to 80% of the total area of ​​the grid 32. That is, the second surface 35 of the lattice 32 contains about 20 to 70% of the knee area.

The specific arrangement between the individual channels 36 and the channels 36 shown in Figure 2 is only one possible way of arranging the channels 36. There are a number of preferred arrangements between the individual channels 36 and the channels 36. Some of these preferred placements and spacing are set forth in U.S. Patent 4,528,239 (Deflection Member, Paul D. Trokhan, July 9, 1985), column 8, lines 35-58, which is incorporated herein by reference. However, one particularly advantageous arrangement between the channels 36 and the channels 36 is the double-sided stepped opening formation shown in Figure 2. It can be seen from Figure 2 that in this particularly advantageous arrangement and spacing of the openings, the openings 42 of the channels 36, such as the first channel openings 42, are of such size and spacing that the edges of the channels 36 extend past each other in any direction.

In one particularly preferred embodiment of the papermaking belt 10 of the present invention having openings in the shape of a linear Idaho pattern, the parameters of the channels 36 (i.e., the number, size, and placement of channel openings) are referred to herein as a linear Idaho model 300 with 35% knee surface. The first digit of the above expression represents the number of channels 36 per square inch in the grid 32. Thus, the grid 32 has 300 channels per square inch. The second number (ie. 35% knuckle area) refers to the paper side network surface 34a to the approximate surface area, or knuckle area. In this preferred embodiment, the papermaking belt is constructed so that the backside network surface 35a of the surface area, or knuckle area is about 65%.

The dimensions used to form the channels 36 as well as the total dimensions of the channels and the distance between the channels 36 in the preferred linear Idaho model 300 with 35% knee surface are shown in Figure 19. In the linear Idaho model 300 with 35% knee surface, the following lengths and radii are used to form channels : d_x is 1.0795 mm (0.0425 inches), d₂ is 0.62785 mm (0.024712 inches) and R_x and R₂ are both 0.3050 mm (0.012008 inches). The overall dimensions of the channel openings and the distance between the channels in the first surface 34 of the grid 32 are shown by a series of letters in Figure 19. In Fig. 19, the letter a represents the length in the machine direction (MD), i.e. simply the length of the opening shown in the figure, b the length of the opening measured in the transverse direction (CD), i.e. the width of the opening, c the distance between two parallel openings in the machine and transverse directions, d the distance between parallel openings and e the distance between the parallel openings in the machine direction. In this preferred embodiment, a is 1.6892 mm (0.066506 inches), b is 1.2379 mm (0.048737 inches), c is 0.28153 mm (0.011084 inches), d is 0.92055 mm (0.036242 inches) ) and e 0.30500 mm (0.012008 inches).

Channels 36 have a channel portion between channel openings 42 and 45. These channel portions 41 are bounded by the walls 44 of the channels 36. The general characteristic features of these channel portions 41 and the walls 44 are shown in Figures 2-4. Figures 2-4 show that the cavities formed by the channels 41, i.e. the channels 41, extend through the entire papermaking belt 10 in the thickness direction. As shown in Figure 2, the channels 36 are generally separate. By separate is meant that the channels 36 form separate channels separated by a grid 32. The separation of the channels 36 is particularly apparent from the top view of Figure 2. Channel 36 is described, however, be generally separate because, as shown for example in Figure 7B, the channels 36 may not be completely separated from each other in the second grid 32 on the surface 35 when the backside network 35a is the passageways 37. The channels 36 are also shown to be insulated in the sense that the channels 36 have no connection to each other within the body of the papermaking belt 10. This isolation of the channels 36 from each other is particularly evident in the cross-sectional views of Figures 3 and 4. Thus, the substance (for example, fluids, such as removed from the paper water) the transition from one channel to another is generally not possible unless the transfer is effected outside of the papermaking belt 10 of the frame or if not, such as for example in Figure 37B esittä15 system in the belt, the transfer is effected in the passageways 12 in certain parts 37 of the papermaking belt 10 backside.

Figures 3 and 4 show the orientation of the channels 36 in the grid 32. As shown in Figures 3-4, the channels 36 have a vertical axis denoted Ay. The orientation of the vertical 20 Iin Ay determines the orientation of the channels 36 in the grid 32 relative to the surfaces 34 and 35 of the grid 32. Thus, it should be understood that in the context of the present invention, the vertical axis Ay is not always in a fully vertical position; it is only relatively vertical to the wind and transverse axes A of the channels 36 pi25_L and A_T in relation to. The orientation of the vertical axis Ay of the channels 36 can vary widely from a position in which the vertical axis Ay is oriented generally perpendicular to the first and second surfaces 34 and 35 of the grid 32 to a position in which the vertical axis Ay is oriented so that the channels 36 are formed at some angle to the grid 32. However, the vertical axis Ay of the channels 36 is preferably generally approximately perpendicular to the first and second surfaces 34 and 35 of the grid 32, as shown in Figures 3 and 4.

The cross-sectional profile of the walls 44 of the channels 36 is shown enlarged in Figure 21. The profile of the walls 44 of the channels 36 may be relatively straight, curved, partially curved, and partially straight or irregular when viewed in cross-section. It should be noted that in drawings other than Fig. 21 showing the walls 44 of the channels 36, the walls 44 of the channels 36 are shown schematically as straight lines to facilitate illumination. However, as shown in Fig. 21, it is assumed that the profile of the walls 44 of the channels 36 may be non-linear from the upper surface 34 of the grid 34 to the lower surface 35 of the grid 32.

As shown in Figure 21, the profile of the walls 44 of the channels 36 is a substantially straight line (in the area represented by the number 47) from the first surface 34 of the truss 32 to the area of ​​the walls 44 beginning approximately at the points indicated by the number 48. The points marked 48 are approximate points where the paper-facing side 51 of the reinforcing structure 33 meets. At the points 48 where the paper-facing side 51 of the reinforcing structure 33 meets, the profile of the walls 44 of the channels 36 is more vague. At this point, the profile of the walls 44 of the channels 36 generally becomes somewhat irregular. The portion of the walls 44 of the channels 36 having the irregular profile is indicated by the number 49 in Fig. 21. The irregular portion 49 of the profile of the walls 44 of the channels 36 is formed when the liquid photosensitive resin is cured into a lattice 32. The ultraviolet light used to cure the resin is supplied by light sources which are placed in the paper-reinforcing structure above the site of each side 51 and paper side 51 of the liquid photosensitive resin. The light rays diffuse or scatter to a certain extent as they meet the strands of the reinforcing structure 33, causing irregular curing of the photosensitive resin.

Thus, the exact starting point II of the irregular portion of the walls 44 will vary depending on where the reinforcing structure 33 meets.

The relationship of the walls 44 of the channels 36 to each other (i.e., the inclination of the walls) may vary from cases where the walls 44 are parallel to cases where the walls 44 are tilted either outward or inward from the upper surface 34 of the grid 32 toward the lower surface 35. Since the walls 44 of the channels 36 form the inner walls 44a of the lattice 32, as shown in Figures 2-4, the inner walls 44a of the lattice 32 may also be inclined. As used in connection with the inclination of the walls 44 of the channels 36 or the inner walls 44a of the lattice 32, the term outward means a relationship in which the distance between the opposite walls 44 or the inner walls 44a changes from smaller to larger. The term inward refers to the opposite relationship (i.e., a relationship in which the distance between the walls 44 or the inner walls 44a changes from larger to smaller).

Figures 1A and 1B show one embodiment of the channels 36 in which the walls of the channels 36 are parallel to each other. Figures 2-4 show a preferred embodiment of the present invention, in which the conduits 36 form the interior of the walls are inwardly inclined from the top surface 34 of the framework 32 of the framework 32 toward the bottom surface 35. When the walls 44 of the channels 36 are tilted either inwards or outwards, the inner walls 44a of the lattice 32 have the opposite relationship to each other. As shown in Figures 2-4, when the walls 44 of the channels 36 are inclined inwardly from the upper surface 34 of the truss 32 toward the lower surface, the inner walls 44a are thus inclined outwardly from the upper surface 34 of the truss 32 toward the lower surface 35. The inclination of the walls 44 and the inner walls 44a is controlled by collimating the light used to cure the photosensitive resin.

The grid 32 of the inner walls 44a are tapered outwardly from the top surface 34 of the framework 32 of the framework 32 toward the bottom surface 35 to the extent that the paper side network

34 a surface area of ​​less than about 70% of the framework 32 of the total surface area of ​​the framework 32 and the second surface 35 of the backside network 35a of the surface area of ​​at least about 45% of the total surface of the framework 32-Alsta. In a particularly preferred embodiment, the interior walls 44a are tapered such that the paper side network surface area 34a (first surface knuckle area A ^) is approximately 35% of the total surface area of ​​the backside network surface area 35a (second surface knuckle area A_N2) Is about 65% of the papermaking belt of the present invention, the back side 10 of the total surface area prior to the formation of the passageways 37 in the backside network 35a. In this particularly preferred embodiment of the invention, the conical angle of the walls 44 of the channels 36, a_T in Figure 21, is about 15 degrees to the vertical.

Figures 3 and 4 show the relationship between the lattice 32 and the reinforcing structure 33. As shown in Figs. 3 and 4, the reinforcing structure 33 is generally located closer to the back side of the papermaking belt 10 than the paper-contacting side 11 of the belt. Although it is possible to form a belt in which the reinforcing structure 33 is placed closer to the paper side 11, such a structure is not preferred.

There are three main reasons why the reinforcing structure 33 is placed closer to the back of the papermaking belt 10. One reason is that the reinforcing structure 33 is generally placed against the casting surface during formation and, as a result, only a limited amount of resin is generally present between the reinforcing structure 33 and the casting surface. Another reason is that it is often advantageous for the reinforcing structure 3 to act as a tread, i.e. as a machine contact material, when the resin lattice portions on the back side 12 of the papermaking belt 10 wear thin because the reinforcing structure 33 provides a more durable surface , over which the papermaking belt 10 passes. The final reason is that a portion of the resin framework 32 covering the reinforcing structure 33 is of efficient design and depth for reinforcing 33 of the paper 36 to form the desired types of channels in the structure 51 on the surface side. The part of the resin grid 32 covering the reinforcing structure 33 is called overload and is denoted t_o in Figure 21. This overload allows the channels 36 to properly fulfill their function of providing an area into which the fibers in the paper web can be directed so that these fibers can rearrange without disturbing the strands of the reinforcing structure 33.

When it is said that the reinforcing structure 33 is placed closer to the back side 12 of the papermaking belt 10, these dimensions may vary. In a preferred embodiment of the papermaking belt 10 of the present invention, a typical preferred woven element having overlapping warp threads has a thickness of about 0.254 mm to 0.94 mm (10 to 37 mils). Resin overload t_o the thickness is about 0.102 to 0.672 mm (4 to 30 mils). When overload t_o is in the preferred range, the thickness of the composite papermaking belt 10 is generally about 0.356 to 1.70 mm (14 to 67 mils). Some applications might require that the overload t_othe thickness is about 0.051 to 6.35 mm (2 to 250 mils). This would, of course, change the overall thickness of the composite papermaking belt 10 accordingly.

Figures 3 and 4 show 35 The characteristics of the papermaking belt 10 and the backside 12 of the second grid surface. 3 and 4 are shown in the figures, the papermaking belt 10 has a textured backside 12. It is this textured backside 12 which is also referred to herein as the backside texturing or backside texture, is very important in the context of this invention. The term as used herein with respect to the texture of the papermaking belt 12 of the back side of means 12 to the characteristic of the backside, created by discontinuities or nonplanar interruptions in an ordinarily smooth or planar surface. These discontinuities, i.e., non-planar breaks, may comprise protrusions from the plane of such a surface or recesses in such a planar surface.

Figures 22A to 22C show that the texture of the backing surface can be provided by different parts of the papermaking belt when the belt comprises a lattice and a reinforcing structure. It should be understood, however, that the specific types of backing surface texture shown in Figures 22A-22C may not be present in the papermaking belt 10 of the present invention. It is possible that a texture similar to that shown in Fig. 22B could be formed on the papermaking belt of the present invention, but it is more likely that the texture is similar to that shown in Figs. 22A and 22C. Figures 22A - 22C show that the backside texture in general can be achieved by the passageways 37 that provide surface texture irregularities 38 in the framework 32 to the second surface 35 in the backside network 35a; each of the reinforcing structure 33, side 52 of the distinctive features of or both the surface texture irregularities forming passageways that the reinforcing structure 33 of the machine side 52 of the distinctive features of. These terms are defined and 52. The characteristics of each of the reinforcing structure 33 side will be described below. Each alternative way to provide a background texture is then considered with reference to Figures 22A-22C.

As used herein, the term passageways refers to the spaces through which air may pass. The term walkways should not be construed to include spaces of a particular shape and size. Thus, the passageways 37 described herein are not limited to spaces resembling tunnels or the like.

As used herein, the term surface texture irregularities (or simply irregularities) means any discontinuity or non-planar breakage in a normally smooth or planar surface, such as protrusions from a smooth surface plane and / or depressions in such a surface. The irregularities 38 comprise those portions which constitute the irregular or uneven portions in the backside network 35a of the second grid 32 of the surface 35a. The surface texture irregularities 38 can be any discontinuities, or breaks in the resinous material which forms the backside network surface 35a, or any of the backside network surface 35a from which there is removed from the resin or with a resin is placed into the network surface 35a.

Figures 22A - 22C are shown in each of the reinforcing structure 33 of the machine of the characteristic features of the side 52, that side may form the backside texture or be involved in its formation. As shown in Figures 22A - 22c are shown, the structural components 40a such as the knuckles of a woven reinforcing structure and the yarns defining a number of levels, which are references for describing the backside 10 of the belt texture. The back side 12 of the papermaking belt 10 of the present invention defines a plane from which the notation P is used_b. The belt back side of the plane defined by P_b is a plane that would be in the same plane as the flat surface if the backside 12 of the papermaking belt 10 of the present invention were placed on a flat surface. 33 for the paper side 51 of the reinforcing structure knuckles (such as paper side knuckles such as 105_bl) determine the level at which the notation P is used_kl. Level P_kl invited paper for the reinforcing structure in the plane defined by side. of each of the reinforcing structure 33 of the machine side knuckles 52 (such as konepuo58

Knee knees, such as 105_b2) determine the level at which the notation P is used_k2. Level P_k2 is called for the reinforcing structure in the side of the plane defined.

As shown in Figures 22A, 22B and 22C, the cross-section 33 of the reinforcing structure of the machine-facing side 52 of the profile has a contour shape that is determined. As shown in these figures, each of the reinforcing structure 33 of the woven side 52 of the contour is defined by some of the warp yarns 52 and some of the weft yarns 54 (which comprise the reinforcing structure 33. The structural components 40a). In addition, Figs. 22A, 22B and 22C show that portions of some of the warp yarns 54 and some of the weft yarns 54 on the machine side 52 of the reinforcing structure 33 form protruding portions 120. As used herein, the term refers to the raised portions 40a of the parts of the warp yarns or weft yarns, or other structural components, which are for the reinforcing structure 33 of the machine-facing side 52 and located inwardly of the reinforcing structure of the machine-facing side of the plane defined by P_k2.

planes and the raised portions as used above 120, the term means, in either the papermaking belt 10. The paper side 11 and the papermaking belt 10 from the backside of the papermaking belt per 10 to the center (ie. the paper side 11 and the backside, between 12 in the middle for passing an imaginary line). In relation to the planes described above, the term outward means from the center of the papermaking belt to either the paper side 11 of the papermaking belt 10 or the back side 12 of the papermaking belt 10. Figures 22A - 22C are formed in the address 120 of the warp yarns 53 and weft elements 54, which are for the reinforcing structure 33 of the machine 52 of the machine side knuckles, such as knuckles 105_b2, in between.

In the preferred multilayer woven reinforcing structure 33 shown in Figs. 22a, 22B and 22C, the protruding portions 120 are generally formed of portions of the warp yarns 53 of the second warp layer D together with portions of the interwoven weft yarns 54. More specifically, a preferred reinforcing structure 33 form raised portions 120 of the second warp layer D of warp yarns 53 parts and 54 parts of weft threads which are both toward the reinforcing structure 33 of the same yarns of the machine side knuckles 1O5₂ between the constituent parts. As shown in Fig. 22D, when the reinforcing structure 33 consists of yarns of circular cross-section and the bottoms of the yarns are in the plane P_k2Some of the raised portions 120 will be formed in addition to parts of the sides of the yarns which due to the curvature of the cross section of the wires differ for the reinforcing structure to the plane defined by side P_k2. They are called raised peripheral portions and are designated 120a in Figure 22D. Fig. 22D shows that in the cross-section shown, these raised circumferential portions 120a are located in the region of the projections A1 of the warp surfaces of the warp yarns 53 in the second warp layer D.

Figures 22A - 22C also show that certain of the raised portions, the inwardly-spaced raised portions 120 ', are located more inwardly towards the planes of the reinforcing structure of the plane defined by side P_k2 than other protrusions. Figs. 22A to 22c show that in the preferred multilayer reinforcing structure 33, some of the internal protruding portions 120 'shown in the figures are assumed to be formed by warp yarns 53 in the second warp layer D. Figs. 22A to 22C show that the points forming the base 53 'of these warp yarns form a surface raised surface defining a plane P_r. Level P_r may also be referred to as the plane defined by the protrusions forming the surface.

DRAWING FIGURES ratio should be noted that the plane defined by the distance of the second warp layer D of warp yarns are the machine-facing side of the reinforcing structure P_k2, is somewhat exaggerated in Figures 22A-22C and also in some other figures to shed light on the matter. It should be understood that in some variations of the reinforcing structure 33, these warp yarns may be at different distances inwardly from the plane. As shown in Figure 22D illustrated a variation of the reinforcing structure 33, the warp yarns of the second warp layer D may even be of the reinforcing structure of the machine-facing side of the plane defined by P_k2. In that case, they are not located inwards at all.

Alternative ways of identifying characteristics of the passageways 37 and surface texture irregularities 38 and each of the reinforcing structure of the machine side are involved in the formation of the backside texture are shown in Figures 22A - 22C. One of the ways in which the papermaking belt of the present invention, the back side 10 texture 12 can be provided is shown in Figure 22A. 22A, the texture is provided entirely by the passageways 37 that provide surface texture irregularities in the network 38 of the framework 32 to the backside 35a. As shown in Figure 22A, 32 of the second surface 35 completely covers the reinforcing structure 33 when the backside texture 12 is provided entirely by the passageways 37 and the irregularities 38.

As used herein when referring to the surfaces of the lattice 32, cover means that said side of the reinforcing structure 33 is located entirely between the first and second surfaces 34 and 35 of the lattice 32. The surfaces of the lattice 32 are here considered to cover that side of the reinforcing structure 33 when they are arranged as mentioned, although there are parts of the reinforcing structure 33 which are inside the channels 36 and which do not have resin material on either side.

As shown in Figures 22B and 22C shows the backside texture can be provided partially by the passageways 37 and irregularities 33 per machine 38 and partially of the reinforcing structure of the side 52 of the contour. Fig. 22B shows one alternative situation in which the second surface 35 of the lattice 32 generally does not cover any parts of the reinforcing structure 33, so that the machine-facing side 52 of the reinforcing structure 33 is exposed. Fig. 22C shows another alternative situation in which the second surface 35 of the lattice 32 covers parts of the reinforcing structure 33 on the machine side 52 and leaves the other parts of the reinforcing structure 33 exposed.

Figures 22A - The types of backside texturing shown 22C are the three basic backside texturing type. These types of backside texturing is called for convenience the positive backside texture; negative backside texture, and both positive and negative backside texture combination.

Figure 22A such as that of the positive backside texture is meant that the passageways 37 extend from the plane defined by the backside 10 of the belt P_b each of the reinforcing structure defined by the machine-facing side of the plane P_k2. As shown in Figure 22A, the texture is positive for the reinforcing structure involved in the side of the plane defined by P_k2is inward of a plane defined by the back side P of the papermaking belt_b. Thus, the reinforcing structure 33 is located entirely between the first surface 34 of the lattice 32 and the second surface 35 of the lattice 32.

The second and perhaps easier way of looking at positive backside texture is to look at the passageways and the irregularities 38 and a reinforcing structure defined by the machine-facing side of the plane P_k2 rather than the relationship between the ratio of the passageways 37 and surface texture irregularities 38 of the papermaking belt, the backside of the plane defined by P_b. 22A, in the case of positive backside texture such as that of the passageways 37 are positioned outward of the plane P_k2, defined by the machine side of the reinforcing structure. The surface texture irregularities 38 extend outward from the plane defined by the machine-facing side of the reinforcing structure P_k2.

such as negative backside texture shown in Figure 22B, it is meant that the passageways 37 extend inward toward the machine of the reinforcing structure of the plane defined by side P_k2 per level P_kl, defined by the paper side of the reinforcing structure. Exclusively negatively textured papermaking papermaking belt back side of the plane defined by P_b and the plane defined by the machine-facing side of the reinforcing structure P_k2 are the same thing.

Figure 22C such as by the positive and negative backside texture means that the presence of both kulkutietyyppiä described above. Thus, some of the passageways 37 are disposed inward of the plane defined by the machine-facing side of the reinforcing structure P_k2 and some of the passageways 37 are positioned outward from the plane defined by side luj per machine ittavan the structure. The positive and negative backside texture, the machine for the reinforcing structure to the side of the plane defined by P_k2 located inwardly from the plane defined by the papermaking backside of the belt P_b.

on the basis of three figures discussed above analysis it is evident that the backside of the papermaking teksII containing different types of luck of the tread is different.

As shown in Figure 22A, the belts having a positive backside texture koos5 tread upon, (at least initially) in whole resin material. When the surface texture irregularities 38 form a jagged projections extend over the machinery employed in the papermaking, these projections will tend to wear off of the belt 10 after the number of revolutions, so that at some point the wear surface will become virtually the same as the machine-facing side of the reinforcing structure is defined by the plane P_k2. The new wear surface comprises per reinforcing structure 33 of the side 52 and the plane P_k2a combination of resin from an upgraded lattice 32. At this point, there is a very limited number of passageways 37 along which air can pass through the surface 35 of the grid 32.

As shown in Figure 22B, belts having a negative backside texture, the original kulutus20 surface generally consists solely of the reinforcing structure 33 of the machine-facing side 52 of the parts. In the case of negative texturing, the original tread thus consists of polyester (or some other material as defined above), which is generally more durable than the resin material that forms the lattice 32. As shown in Fig. 22B, the negatively textured belts may further have passageways, such as 37 ', extending inwardly from the machine-facing side 52 of the reinforcing structure 33. As the belt wears so that the tread coincides with the machine-facing side 52 of the reinforcing structure 33, these passageways 37 'further provide openings on the back of the belt 12. Thus, belts having a negative backside texture, generally allow the escape of kuluttuaan remain somewhat across their backside 12 to air.

As shown in Fig. 22C, in belts having a combination of both negative and positive textures, the tread consists at least initially entirely of a resin material forming a lattice 32. As the knurled protrusions comprising this resin material wear out, the tread becomes, as in the belt of Fig. 22A, itself the same as the reinforcing raken10 Coffee machine-facing side of the plane defined by P_k2. However, one difference between the belts shown in Figures 22A and 22C is that due to the negative texture, the latter belt still has passageways 37 after the positive texture. Therefore, it is contemplated that it is generally preferred that the embodiment of the present invention have at least some negative texturing to preserve the textured tread on the back side after the original texture has been removed.

In this invention, the texture is formed papermaking belt 10 of the rear side 12 by manipulating the liquid photosensitive resin which cures to form a grid 32. The liquid photosensitive resin is manipulated to the reinforcing structure 33 around, so that 32 of the second surface ris25 Tikon 35 in the backside network formed by the passageways 37 and pintateksturin irregularities 38. The location, characteristics and distribution of the passageways 37 and irregularities 38 in the papermaking belt are therefore generally described in relation to the reinforcing structure 33. A few terms are defined which serve as references to describe the location and characteristics of the passageways 37 and the surface texture irregularities 38 in relation to the characteristic features.

Il

As shown in Figures 12 and 12A, both paths and surface texture irregularities 38 determine the projections of the surfaces. It is to be understood that the passageways 37 and surface texture irregularities 38 are shown in a certain manner in Figures 12 and 12A for further processing and that the types of passageways 37 and irregularities shown may not be present in all embodiments of the papermaking belt of this invention. The projection of the surface of the passageways 37 shown in Figures 12 and 12A is represented by the letter A_p. As used herein, the projection of the surface of the passageway 37 means the area defined by the projection of the passageway 37 in the z direction. The projection of the surface of the irregularity 38 shown in Figures 12 and 12A is represented by the letter A_x. As used herein, the surface projection of the surface texture irregularity 38 means the area defined by the projection of the irregularity 38 in the z direction.

In this specification, when the surface projection of the path 37 or surface texture irregularity 38 (or the surface projection of the path 37 or surface texture irregularity 38) is described to be in line, inside or located inside or in other similar terms with respect to one of the surface projections of the reinforcing structure 33 (or grid 32), the path or irregularity is within the boundaries of the surface design at all levels, into which that element could be projected in the z direction. In other words, the path or irregularity within the surface projection could be located above the surface projection determining element or below the surface projection determining element, or even partially above and partially below that element. In addition, parts of the pathway or irregularity could be in one or more planes on which the element in question is projected in the z direction.

Figures 12 and 12A show some possible locations of the passageways 37 and surface texture irregularities 38 described above. Referring to Figures 12 and 12A, from left to right, the first passageway 37 shown is partially within the warp surface projection A1. Part of this passage 37 is also outside the warp surface projection A1. On the right side of the first passageway 37 there is an irregularity 38. The irregularity 38 shown in Figures 12 and 12A is the warp surface projection A *? indoors. To the right of the irregularity 38 is the third passageway 37. The third passageway is entirely in the projection A of the pore surface._pi indoors. The fourth path 37 is shown to the right of the third path 37. The fourth passageway 37 is completely within the warp surface projection A1.

It should be understood that when the path 37 or the surface texture irregularity 38 is described relative to the surface projection, this means that the element in question is located in a generally defined manner relative to the surface projection. However, there may be small portions of the path 38 or irregularity 38 that do not exactly correspond to that area. These slight shifts in the actual position of the element from the surface projections can be due to at least two factors. One factor is that the elements in question (such as paths and irregularities) are extremely small and very small changes in the position of the element grow disproportionately large relative to the projections on the surface. This can cause the element to be slightly outside the boundaries of the surface projection. Another factor is that the positions of the pathways 37 and the surface texture irregularities 38 are sometimes obtained in such a way that the light rays which harden the liquid photosensitive resin forming the lattice 32 pass through the reinforcing structure 33. The direction of travel of these light rays is not always exclusively in the z direction, and as a result the projection of the areas described above

II when stacked from the direction of the light source may be slightly different from the projection of the same areas in the z direction.

The characteristic features of the passageways 37 and the surface texture irregularities 38 are best discussed with reference to Fig. 21. As shown in Figure 21, there is a relationship between the passageways 37 and the surface texture irregularities 38. The passageways 37 are openings for the passage of fluids or, more specifically, air or air and water along the second surface 35 of the grid 32. When the TA10 ustapuolen network 35a formed by the passageways 37, they provide the surface texture irregularities 38. The irregularities 38 are, therefore, 35a of portions of the framework 32 of the backside network, which surround the passageways 37. In the general sense, walkways themselves 37, however, provide surface texture irregularities because they are also discontinuities or irregularities in the grid 32 in the backside network 35a.

As shown in Figure 21, both the passageways 37 and the irregularities 38 differ from the passages 36 passing through the grid 32. The term differ from the channels meant that the passageways 37 and the irregularities 38 which form deviations of the framework 32 otherwise silestä and continuous backside network 35a, it is separated from the channels 36 formed through the holes 41. 26 formed by holes in channels 41 is therefore not meant to categorize the passageways or surface texture irregularities .

Figure 21 shows the physical characteristics of the individual passageways 37. It is to be understood that Figure 21 is an exaggerated schematic view of part of the papermaking belt which shows a range of different shapes of passageways 37 and surface texture irregularities 38. Although shown in Figure 21, selection of the backside texturing is useful in describing the general 38 The characteristics of the passageways 37 and irregularities, non Figure

21 presented by the particular backside texturing may not actually be found in the papermaking belt of the present invention, the papermaking belt 10. The particular backside texturing depends on the method used to make the belt. These particular textures are discussed in connection with enlarged photographs showing belts formed following the method of making a papermaking belt in accordance with the invention described herein.

As shown in Figure 21, passageways 37 may have sides, generally designated 66. These sides may have an unlimited number of different shapes. They may be curved or relatively straight in cross-section or partially curved and partially straight. Often, however, the sides 66 of the passageways 37b are so irregular that they cannot be precisely defined.

As shown in Figure 21, the sides 66 of the passageways 37 may extend from relatively vertical (i.e., z-oriented) to relatively horizontal (y and x oriented) sides. The angle formed by side 66 with respect to the z direction is denoted by a_Bin Fig. 21. However, it is to be understood that in the case of a side-curved or irregular path 37, the angle a_e the size varies with the angle a formed by page 66_Baccording to the reference points used for measurement.

In addition, each passageway 37 may have different numbers of different sides 66. The number of sides 66 may vary from a substantially continuous continuous curved wall to a virtually unlimited number of sides of different cross-sections. In the simplified cross-section shown in Fig. 21, some of the passageways 37 appear to have sides 66 resembling inner walls, sides 66a. In addition, some of the passageways 37 with relatively vertical walls 66a have a side resembling a roof, 66b. However, one side of the lane 37 is

II always open. Open pages are denoted by 66c in Figure 21.

In addition, although the passageways 37 are generally extremely small, they have a predetermined height h_p, width w_p, distant 5 September apart p_p and cross-sectional area A_xp.

As shown in Figure 21, the height hp of a passageway is the distance measured in the z direction the plane defined by the backside of the belt P_b to a point such as 66d on the inner surface of the passageway 37. As shown in Fig. 21, the height h of the different parts of the single path 37_p may vary in the width direction of the passageway 37. In addition, the second surface 35 of the backside network 35a of the various passageways 37 in the height h_p may vary from path to path.

Lane 37 width w_p is the distance between two points on the opposite side walls 66a of the passageway 37, measured in a direction according to the selected cross-section in the XY plane. If one curved surface forms the side walls, the width of the passageway w_p is the distance between two points on opposite sides of the curved surface, measured in the XY plane. As shown in Fig. 21, the width of the different portions of a single path may vary depending on which portion of the path 37 the width is measured. In addition, the second surface 35 of the backside network 35a of different width of the passageways 37 can vary from passageway to passageway.

Cross-sectional area of ​​the walkway A_xp represents the area shaded in slashes in Figure 21. The cross-sectional area A of the passageway_p route is the inner part of the cross-sectional area which defines the inner part of the backside of the belt defined by the plane P_b passing an imaginary straight line. Yk30 total cross-sectional area 37 of passageways 37_pT is important because it is through these areas that air escapes as the papermaking belt of the present invention passes over the suction box during papermaking.

The distance between the parallel passageways 37 is represented by the letter s_p in Fig. 21. The distance s between the parallel wefts 377070_p is defined herein using two reference points located on the sides of the irregularities 38 bounding that path 37. These two points, denoted by 109 in Fig. 21, are on the sides of the irregularities 38, referred to herein as the adjacent sides of the irregularities 38. The adjacent sides of the irregularities 38, denoted 67a, are referred to as such because they also form the sides 66 of the parallel passageways 37. The selected two reference points 109 are the neighboring sides 67a in points that are measured in the z direction of the belt closest to the plane defined by the backside of the P_b. In Fig. 21, these two reference points 109 are in fact in the plane P_b, but this is not always the case. Distance between parallel passages 37 s_p, shown by the arrow in Fig. 21, is the distance measured in the XY plane between the reference point 109 on the adjacent side 67a of the irregularity 38 between the passageways in question and the next reference point 109 on the opposite neighboring side 67a of the same irregularity 38.

The overall model of the distances between the passageways 37 determines the distribution of the passageways 37. The passageways 37 may be distributed in an unlimited number of different ways to network the framework 32 to the back side 35a. The distribution of the passageways 27 can be, for example, random, uniform, regular or according to a certain pattern.

One example of randomly spaced paths 37 is the paths 37 of a belt 10 comprising a combination of positive and negative texturing, shown in Figure 22C. As used herein, the term uniform means that the density (i.e., number) of the passageways 37 is approximately the same over the entire surface, even if the passageways 37 do not form any particular pattern. As used herein, the term regular means that the distance between parallel paths s_p is about the same

II across the entire backside network 35a. An example of regularly-spaced passageways 37 are the positive backside texturing belt 10 with the passageways 37, which is shown in Figure 22A. Figure 22A by the belt 10 also serves as an example of uniformly-spaced passageways in that the density of passageways is approximately the same on the backside network 35a over the entire surface. The distance between the parallel passageways 37 of the belt 10 shown in Fig. 22A is sufficiently similar that the passages of the passageways 37 shown therein can also be considered to follow the pattern. Another example of passageways which are distributed in accordance with a pattern are the passageways of the belt with negative backside texturing which is shown in Figure 22B. However, the walkways divided according to the figure in Fig. 22B do not include the walkways 37 '. There are a virtually limitless number of combinations of the basic types of background texture shown in Figures 22A-22C and the distances between the passageways described herein. For example, Figure 31 manufactured by the method according to the present invention, the partially formed composite belt 10 'provides an example of both regularly-spaced passageways 37 and the passageways 37, which are distributed in accordance with the belt pattern, wherein the positive and negative backside texture yh25 combination.

The passageways 37 may also be distributed in generally all parts of the second surface 35 of the truss 32. This means that any portion 35a and the passageways 37 can be found in the backside network surface does not exist in one or more of the backside network surface 35a of the area from which the passageways 37 are not provided. In the case where the reinforcing structure comprises a woven element, the passageways 37 can thus be located in the projection A of the reinforcing surface of the reinforcing structure._R or in the projection of an open pin35 nan A_o. By defining that the breakdown has occurred broadly across the entire backside network 35a and the entire backside network, means that, while the passageways 37 can be found in virtually any prescribed backside network

Section 35a, the passageways 37 do not necessarily cover the entire backside network 35a.

Figure 21 shows the physical characteristics of the individual irregularities in the surface texture. In addition, surface texture irregularities are generally described in Broadston, Mark's Standard Handbook for Mechanical Engineers, Surface-Texture Design, Production and Control, McGraw-Hill 1967, pp. 13-106-13-112, which is incorporated herein by reference. As shown in Fig. 21, the sides 67 of the surface texture irregularities 38 are commonly denoted 67. The surface texture irregularities 38 of the present invention may (as well as the passageways) have sides 67 with an unlimited number of different shapes. As with the passageways, the sides of the irregularities 38 may be curved or relatively straight when viewed in cross section, or partially curved and partially straight. However, the pages 67 of the irregularities 38 are often so irregular that they cannot be precisely defined.

As shown in Figure 21, irregularities

38 pages 67 may extend relatively vertically (i.e.,

from the z-direction) to relatively horizontal (from the x and y directions). The angle formed by the side 67 of the irregularity 38 with the direction z is denoted aj in Fig. 21. However, it should be understood that in the case of an irregularity 38 having curved or irregular sides, this angle depends on the reference points used for the angle a formed by the side 67 of the irregularity 38._x the measurement.

In addition, each irregularity 38 may have varying numbers of different pages 67. The number II of pages 67 may vary depending on the shape of the irregularity 38. For dome- or knob-shaped irregularities, the page (s) 67 of the irregularity 38 appear (appear) from a single continuous curve as a line when viewed in cross section. In cases where the irregularity 38 has a more complex shape, there may be a virtually unlimited number of pages 67 with different cross-sections.

Fig. 21 shows the adjacent sides 67a of the irregularities 38 described above formed by the inner walls 66a of the passageways 37. As shown in Figure 21, these adjacent sides 67a are often relatively different in length, because adjacent sides 67a of a given irregularity 38 may be formed by the side walls 66a of two or more radically different paths 37a.

Figure 21 also shows that one or more of the sides 67 of the irregularities 38 may not be formed of the same structure that forms the walls of the adjacent passageways. These pages are referred to as independently formed pages of irregularities and are denoted 67b in the drawings. Often, these independently formed sides 67b of the irregularities 38 form part of the tread on the back side 12 of the belt 10.

In addition, as in the case of passageways 37, although the irregularities 38 are generally extremely small, they also have a limited height h_x, width w_x, distance s_x and cross-sectional area A_xl. As shown in Figure 21, the adjacent sides 67 of the irregularities 38 often form the boundaries of the irregularities 38. Since the adjacent sides 67a of the irregularity 38 can be quite different, it may be difficult to express the exact height of the irregularity 38 as well as the width and cross-sectional area A_xl.

To define these characteristic features of the irregularities 38, a random but uniform point is selected for taking these measurements. This reference point is denoted by 110 in Fig. 21. The reference point 110 is the point which is the shortest of the adjacent sides 67a of the irregularity 38. More specifically, it is the shortest of the coterminous sides 67a of the point, which is the greatest distance inward from the plane defined by the backside of the belt P_b. Figure 21 shows that point 110 may be at two different locations in the case of adjacent irregularities 38.

As shown in Fig. 21, the height h of any point of the irregularity 38_x is the distance measured in the z-direction from the plane passing through the reference point 110 of said irregularity 39 to the point of irregularity 38 of interest. As shown in Fig. 21, the height h of the different parts of the single irregularity 38_x may vary in the width direction of the irregularity. In addition, the backside network 35a of the various irregularities 38 in the height h_x may vary from irregularity to another.

Irregularity 38 width w_x is the distance between two points on opposite sides 67 of the irregularity 38, measured in either the x or y direction, or in a direction between them in the XY plane, depending on the cross section used. If the sides 67 form a single curved surface, the width w of the irregularity_x is the distance between two points on opposite sides of the curved surface, measured in the XY plane. As shown in Fig. 21, the width w of the different parts of the single irregularity 38_x may vary depending on which part of the irregularity 38 the width is measured. In addition, the width 38 in the backside network 35a of the various irregularities w_x may vary from irregularity to another.

il

Irregular cross-sectional area A_xi is also shown by the shaded area in Figure 21. The cross-sectional area A of the irregularity_xl is the reference point 110 to the plane defined by the imaginary line, and a belt extending backside P_b the area of ​​part 38 of the intervening irregularity, measured from a given cross-section.

The irregularities 38 also have a distance s between the parallel irregularities 39_x. As shown in Fig. 21, the distance of the irregularities 39 in a given direction s_x is the distance measured in the XY plane between one reference point 109 on the adjacent side of the irregularity 38 and the reference point 109 on the nearest neighboring side 67a of the next irregularity 39.

The overall pattern of the intervals between the irregularities 38 determines the distribution of the irregularities 38. As well as walkways irregularities 38 may be distributed in an unlimited number of different ways to the grid 32 in the backside network. The distribution of irregularities can be random20, uniform, regular, or according to a certain pattern. As used herein, the term uniform means that the density (i.e., number) of irregularities 38 is approximately the same over the entire surface, even if the irregularities 38 do not form any particular pattern.

As used herein, the term regular means that the distance s between parallel irregularities_x is approximately the same across the entire backside network 35a. Similarly, the passageways 37 in the case of the irregularities 38 may be distributed across the backside network generally all parts. When the irregularities 38 are generally distributed to all parts of the backside network 35a, it is meant that while the irregularities 38 can be found almost anywhere in the backside network 35a in point koh35, the irregularities 38 do not necessarily cover the entire backside network 35a. Examples of different distributions of the irregularities 39 are shown in the figures of the accompanying drawings, which show the corresponding types of distribution of the passageways 37.

In addition, the irregularities 38 of the features described above, they may be described in the framework 32 in the backside network 35a as either projections or recesses. If the irregularity 38 is referred to herein as either a protrusion or a recess, the reference frame used to describe the irregularity 38 is level P_k2, defined by the machine side of the reinforcing structure. Any irregularity 38 directed outward from this plane in the z direction is a protrusion. Any irregularity 38 located in the direction 15 inward from the plane p_k2, is a recess.

the papermaking belt 10 of the present invention, a preferred embodiment of the textured backside 12 of the specific characteristics depend on the method used to make the belt 10. These special features are generally illustrated in the enlarged photographs of Figures 36A-36C and 37A-37C, and are discussed in describing various alternative method versions used to make the belts shown in the photographs. However, there are certain general properties that are common to belts made with different alternatives to the basic method. These features are best described with reference to the schematic drawings 22A-22C.

Fig. 22A schematically shows an alternative embodiment of a papermaking belt 10 according to the present invention. Figure 22A is illustrated in an alternative embodiment, all of the passageways 37 are positioned outward from the plane defined by the machine-facing side of the reinforcing structure P_k2. Figure 22C shows another papermaking belt 10 embodiment, having a plurality of passages disposed in the home 37 of the reinforcing structure Netta inwardly towards the plane defined by the side P_k2 and the plane defined by the plurality of passageways 37 outwardly from the reinforcing structure of the machine towards the side of P_k2. In the latter alternative embodiment, at least some of the passageways 37 are disposed inward of the plane defined by the machine-facing side of the reinforcing structure P_k2, are located in the pores 39 of the reinforcing structure 33 so that a portion of the surface projection of the passageways 37 corresponds to a portion of the open surface project10 of the reinforcing structure 33. In either alternative embodiment, the backing surface 12 of the papermaking belt 10 has sufficient fluid throughput to allow at least about 1,800 standard cubic centimeters / minute to escape across the textured surface.

It is hypothesized that the problems that arose with the use of prior smooth backing papermaking belts were at least in part due to the extremely sudden effect of suction pressure on the paper web as the previous belt carried the paper web over the vacuum dewatering machinery used in the papermaking process. It is assumed that the previous smooth-backed papermaking belts actually formed a temporary barrier over these vacuum sources. When the guide channels of the papermaking belt of the previous type were then encountered, the suction pressure was applied extremely abruptly to the fibrous web on top of the resin lattice. The sudden application of this suction pressure is believed to have caused the abrupt deflection of the highly moving fibers in the fibrous web, which was sufficient to allow these moving fibers to pass completely through the papermaking belt. The difference in the guiding of the fibers of the fibrous web as the previous belt 10a and the papermaking belt 10 of the present invention are carried is schematically illustrated in Figures 23A and 23B and graphically in Figure 24.

Fig. 23A shows putative events as prior papermaking belts 10a encounter a vacuum dewatering apparatus used in the papermaking78 process, such as a suction box 24. Fig. 23B shows putative events when an improved papermaking belt 10 according to the present invention encounters such a suction box 24. Fig. 24 is a graphical representation of the suction pressure (pressure difference) applied to the fibers of the elementary web 18 as the papermaking belts shown in Figs. 23A and 23B pass over the vacuum gap in the suction box.

While each of the papermaking belts 10a and 10, respectively shown in FIGS 23A and 23B comprises a framework 32, having a first surface 34, second surface 35 and lujttava structure 33, the belts differ in that 32 second surface of the belt 10 of the grid 35 in the backside network 35a is a textured, while the belt 10a of the framework 32 to the backside network 35a is smooth. It should be understood, however, that there are numerous other differences (including, but not limited to, the shape of the channels and the type of reinforcing structure used) between the papermaking belt 10 of the present invention and prior art belts that are not shown in Figures 23A and 23B. Figures 23A and 23B are intended to show differences in belt performance resulting from differences between their backs. For simplicity and clarity, other differences are therefore omitted from Figures 23A and 23B.

As shown in Figures 23A and 23B, both belts 10a and 10 carry a primary web 18 (with individual fibers designated 18a) on the first surface 24 of their grid 32. In the figures, a portion of each belt 10a and 10 passes through one slot 24d in the suction box 24. The parts of the suction boxes shown also include a front surface, the surface 24c of the suction box_x, which is first encountered as the papermaking belts travel in the machine direction (from left to right in the figures) in the papermaking process, and the after-surface, the suction box surface 24c₂, which is the surface of the suction box 24 which is encountered after the papermaking belts pass over the vacuum gap 24d. On each of the surfaces 24c_x and 24c₂ in addition, there is an edge adjacent the upper surface of the vacuum gap 24d, such as the edge 24b of the front surface of the suction box_x and a suction box trailing edge 24b₂. The suction pressure V is applied by a vacuum source (not shown) which causes pressure in the direction of the arrows shown in the figures on the belts and elementary webs 18. The suction pressure V removes some water from the elementary web 18 and directs and rearranges the elementary web fibers 18a into the grid 32 channels.

It is believed that the framework 32 to the back side 35a of the flat nature of the network in Figure 23A, a vacuum seal of the framework 32 of the second surface 35 of the suction box 24 and the leading surface 24c_x As the belt 10a travels to the right, a vacuum gap 24d is encountered, the barrier is abruptly broken, and the suction pressure V is abruptly applied to the elementary web 18. This causes the fibers 18a of the elementary web 18 to abruptly guide the channels 36 and some of the more mobile fibers 18 , passes completely through the belt 10a and accumulates at the trailing edge 24b of the suction box 24_x. It has been found that these fibers 18a 'eventually accumulate to such an extent that they accumulate as fiber lumps on the back surface 24c of the suction box.₂ and form ridges over which the papermaking belt 10a has to pass.

Since the belt 10, the backside 12 (particularly the backside 32 of the grid network 35a) are testuroitu, Figure 23B instead of passageways 37 through which air can papermaking belt 10 of the back surface 12 and the leading surface 24c, a suction box_x , whereby the framework 32 of the backside network 35a of the suction box 24 and the leading surface 24c closing \ between eliminated. This air inlet is shown schematically by large arrows V_L. As shown in Fig. 23B, the air inlet V_L allows the fiber 18a in the elementary web 18 to be guided more gradually. Little, if any, fiber passes through the papermaking belt 10 and accumulates at the trailing edge 24b of the suction box₂. In addition, it is believed that the papermaking belt 10 shown in Figure 23B, the textured backside network 35a may also serve a scrubbing or cleaning function to remove the suction box and the second edge 24b₂potentially accumulating fibers.

2. Method of Making a Papermaking Belt As discussed above, the papermaking belt 10 may take a variety of forms. Although the method of forming the belt 10 in papermaking 10 is irrelevant, as long as the belt has the above-mentioned characteristics, certain methods have been found to be useful. As a background, a method of making a guide member (i.e., a porous member) that does not incorporate the improvements disclosed herein is described in detail in U.S. Patent 4,514,345 (Method of Making a

Foraminous Member, Johnson et al., April 30, 1985). This by Johnson et al. the patent is incorporated herein by reference to the extent consistent with this description.

One method of making the papermaking belt 10 of the present invention and some variations thereof will be described below.

One preferred embodiment of the apparatus that can be used to form the endless belt papermaking belt 10 of the present invention is shown schematically in Figure 25. To provide an overview of the entire apparatus for making the papermaking belt of the present invention, Figure 25 has been simplified to some extent. The following figures show the details of this apparatus, and particularly the manner in which the passageways 37 and surface texture irregularities 38 formed in the second surface 32 of the grid 35 in the backside network 35a. At this point, it should be noted that the scale of certain parts shown in the figures may be somewhat exaggerated in the following drawings.

The overall process shown in Figure 25 generally comprises coating the reinforcing structure 33 with a liquid photosensitive polymer resin 70 as the reinforcing structure 33 passes over a forming unit 71 having a textured work surface (i.e., casting surface) 72. As shown in Fig. 25 et seq., The resin 70 is applied to at least one side (and preferably to both sides) of the reinforcing structure 33 so that the coating 70 forms a first surface 34 'and a second surface 35'. The coating 70 is distributed so that at least a portion of the second surface 35 'of the coating abuts the working surface 72 of the forming unit 71. The coating 70 is also distributed so that the paper-facing side 51 of the reinforcing structure 33 is located between the first surface 34 'and the second surface 35' of the coating. Coating the part, disposed between the first surface 34 'and each of 33 paper side reinforcing structure 51 forms a resinous overburden t_o'. Overload t_o'thickness is adjusted to a preselected value. When the reinforcing structure 33 is coated with a photosensitive resin, the liquid resin applied to the machine-facing side 52 of the reinforcing structure is made to flow with the resin possibly flowing through the pores 39 of the reinforcing structure 33 to pattern the textured work surface 72. This provides the second surface 35 'of the coating with areas defined by the textured surface. The liquid photosensitive resin 70 is then treated with light having an activating wavelength (light that cures the photosensitive liquid resin) from a light source 73 through a mask 74 having opaque areas 74a and transparent areas 74b. Those parts of the resin which are shaded or protected from light by the opaque areas 74a do not cure due to exposure. This uncured resin is then removed, leaving channels through the cured resin lattice. The resin to a light having an activating wavelength creates passageways 37 which provide surface texture irregularities 38 in the grid 32 in the backside network 35a in areas where the coating has penetrated into the forming unit 71. The texture of the working surface 72. Changing the casting surface texture provides an opportunity to create virtually any desired types of passageways and irregularities in the backside 10 of the papermaking belt network 35a.

For convenience, the steps of the overall process are divided into a series of steps and will be discussed in more detail in the next reading. It is to be understood, however, that the steps described below are intended to assist the reader in understanding the method of making the papermaking belt of the present invention, and that the method described below is not limited to a particular number and order of steps. It is also possible to divide some of the following steps into two or more steps without falling outside the scope of the present invention.

First phase

The first step in the method of the present invention is to obtain a forming unit 71 with a textured work surface 72.

As described more fully below, there are various ways to provide a forming unit with a textured work surface. These include, but are not limited to, the following: (1) obtaining a forming table, drum, or cylinder having a texture (shown generally in Figure 25); or (2) (i) obtaining a forming unit, (ii) obtaining an element having a textured surface and a surface in contact with the forming unit, and (iii) placing the forming unit

II in contact with the surface of the element for the forming unit (generally shown in Figs. 27 to 31).

The above bases for providing a forming unit 71 with a textured work surface 72 optionally and preferably further include the step of placing a barrier film (i.e., a backing film) 76 between the reinforcing structure 33 and the forming unit work surface 72 during the casting process so that the barrier film 76 protects the forming unit 71 (or forming element); contamination with resin. In one of the most preferred embodiments of the method according to the invention, the textured work surface is provided by the element described above in connection with option (2) and the same element also acts as a barrier film protecting the forming unit from contamination with resin (Figures 30 and 31). The characteristic features of the forming unit 71 and the components associated with the forming unit 71 will be discussed in more detail below.

The forming unit 71 shown in Fig. 25 has a work surface denoted by the number 72. In Fig. 25, the forming unit 71 is shown as a circular element, which is preferably a drum. The diameter and length of the drum are selected according to suitability. Its diameter should be large enough so that the barrier film 76 and the reinforcing structure 33 do not bend unnecessarily during the process. Its diameter must also be so large that the distance traveled on its surface is sufficient so that the necessary steps can be carried out as the drum rotates. The length of the drum is selected according to the width of the papermaking belt 10 to be formed. The forming unit 71 is rotated by a conventional drive not shown in the figure.

Fig. 27 is an enlarged schematic view of one alternative version of the casting process shown in Fig. 25. As shown in Figure 27, the drum is provided with a textured work surface 72 using a textured element such as a textured cover 92. Figure 27 also illustrates for the first time that a preferred rubber cover 91, preferably about 2.54 cm (1 inch) thick, is placed in a preferred embodiment of the method. ) on the forming unit 71. The textured cover 92 is pulled over the hard rubber cover 91. The textured cover 92 has a textured surface 92a and a surface 92b in contact with the forming unit. The texture on the surface of the textured cover 92 is generally designated 93 in the drawings.

It is to be understood that the use of a hard rubber cover and the placement of a textured cover on the rubber cover 91 to form a forming unit 71 with a textured work surface 72 is only one preferred embodiment of the method of the present invention. It is also possible to implement the method of the present invention by omitting the hard rubber cover 91, the separate textured cover 92, or both. The prerequisite is that the outer surface of the remaining element (or combination of elements) is textured. It should be understood that all various combinations of these elements and their equivalents are within the scope of this invention. In order to avoid showing an unnecessarily large number of relatively similar drawings, only preferred embodiments of the present invention are shown. However, a few of the possible combinations can be described with reference to the figures shown. For example, if a hard rubber cover is omitted, the hard rubber cover numbered 91 and the textured cover would appear as one and the same element in the drawings. If the textured cover 92 is omitted, the textured surface would be formed on the hard rubber cover 91. Again, the above-mentioned two elements 91 and 92 appear as one and the same element in the drawings. In one alternative, the surface of the forming unit 71 could be textured and both the hard rubber cover 91 and the separate textured cover 92 could be omitted.

Il

In this case, all three elements 71, 91 and 92 shown in the drawings appear as the same element. Accordingly, the barrier film 76 could be omitted so that it would not be visible in the drawings.

The individual peaks and valleys that form the texture 93 of the textured cover 92 are denoted by the numbers 93a and 93b, respectively. As used herein, the term refers to the peaks of the portions of the textured working surface 72 which, either alone or together with 76 parts of the binder SA barrier film facing inward of the plane defined by the machine-facing side of the reinforcing structure P_k2, when the reinforcing structure 33 is in place on the working surface of the forming unit 71. As used herein, the term valleys refers to those portions of the textured working surface 72 which, either alone or in combination with parts of the barrier film 76 extend outward from the plane defined by the machine-facing side of the reinforcing structure P_k2, when the reinforcing structure 33 is in place on the working surface of the forming unit 71.

The texture of the work surface 72 may be of any type, dimension, or pattern, and may be formed by an element or surface made of any suitable material. The only requirement is that the texture will give the desired amount of backside texture to the papermaking belt 10 according to the present invention, hereinafter referred to as kuvatta25 after the execution of steps. The texture of suitable textured surfaces may have been formed by engraving or embossing. The texture of the surface can be random, uniform, regular, or following the same specified pattern.

Suitable textured surfaces can be formed on virtually any material, including metals, rubber, or plastic surfaces. In addition to materials having a texture formed thereon, a textured surface may be provided with a material having an intrinsic texture, such as a woven elemen86 account (part of which is indicated in Figure 29 by the designation 92 '), a mesh or a wire or the like. Alternatively or in addition, strips of material, such as 92 in Figure 29, (or other shaped pieces of material) of a certain thickness and spaced apart to form a surface with varying height ranges could be used to form a textured surface. In this alternative case, the surfaces 92b of the strips themselves need not be textured. The textured surface is provided by relative height differences between the strip-covered surfaces and the non-strip surfaces. In principle any material that provides texture, is suitable, provided that it gives the correct amount of backside texturing according to the present invention, PA15 perinvalmistushihnalle casting surface is used. It has been found advantageous to use surfaces which have a relatively precise texture, so that the amount of texturing will be determined in general, all of the finished backside 35a of the belt parts of the network.

The forming unit 71 is preferably covered with a barrier film 76 which prevents contamination of the work surface 72 with resin. The barrier film 76 also facilitates removal of the semi-finished papermaking belt 10 'from the forming unit 71. When the textured surface is provided with a component 25 other than the barrier film, the barrier film 76 can generally be any flexible, smooth, planar material that follows the texture of the forming unit 71. This means that the barrier film 76 should be flexible enough to conform to the shape of the surface of the forming unit 71 so that the bare surface of the barrier film 76 has a texture at approximately the same points as the texture of the working surface 72 of the forming unit 71. The barrier film 76 may be made of a polypropylene, polyethylene or polyester film. The barrier film is preferably made of polypropylene and has a thickness of about 0.01 to 0.1 mm.

Il

It is also preferred that the barrier film 76 either absorb light having an activating wavelength or be transparent enough to allow such a light generating unit 71 to work on the working surface 72 which absorbs light. The barrier film 76 is also typically treated chemically to prevent the resin from adhering to its surface and also to ensure that the resin spreads evenly on its surface. This chemical treatment is preferably a corona treatment. In the corona treatment of the barrier film 76, an electric discharge is directed to the barrier film 76 before it is installed in the apparatus shown in Fig. 25.

As shown in Figure 25, the barrier film 76 is fed into the system from the barrier film supply roll 77 by unwinding it and causing it to travel direction of the arrow D2 direction shown. After unwinding from the roll, the barrier film 76 comes into contact with the work surface 72 of the forming unit 71 and is temporarily forced against the work surface 72 by the means described below. The barrier film 76 travels with the forming unit 71 as the forming unit 71 rotates. Finally, the barrier film 76 is separated from the working surface 72 of the forming unit 71 and passes to the barrier film receiving roll 78 on which it is wrapped. In the method embodiment shown in Figure 25, the barrier film 76 is designed to be used once, after which it is discarded. In an alternative arrangement, the barrier film 76 may be in the form of an endless belt running around a set of return rollers where it is cleaned and reused. Other alternative arrangements could have two or more barrier films arranged as described above, and a textured element, such as a textured cover, could be interposed between the barrier films.

The forming unit 71 is preferably also provided with means to ensure that the barrier film 76 remains in close contact with its work surface 72. The barrier film 76 can be attached to the work surface, for example, by gluing

72. Alternatively, the barrier film 76 may be attached to the work surface 72 of the work 88 by a vacuum applied through a plurality of adjacent small openings distributed on the work surface 72 of the forming unit 71. The barrier film 76 is held against the work surface 72, preferably by conventional tightening means not shown in Figure 25.

Figures 30 and 31 show one particularly preferred means of providing the forming unit 71 with a textured work surface 72. In Figures 30 and 31, the portion by which the forming unit 71 is provided with a textured work surface 72 also acts as a barrier film 76 protecting the forming unit 71 from resin contamination. Fig. 30 is thus an enlarged schematic diagram of one variation of the casting process shown in Fig. 25. Fig. 31 is a further enlarged view of the casting surface shown in Fig. 30. The alternative shown in Figures 30 and 31 is advantageous because in such an arrangement, the drum acting as a forming unit need not have a textured surface and no other parts attached to the forming unit (such as a separate cover or hard rubber cover) need to have a textured surface. In this particularly preferred alternative, the barrier pattern 76 also does not have to be conformable, since the barrier film 76 forms a textured surface. The barrier film 76 is also preferably not planar in this alternative, as it should be provided with a relatively permanent textured surface (i.e., a surface that retains its texture under the conditions of the casting process). However, the other general properties of the textured barrier film are the same as those of the textured surfaces described above.

Second phase

the second step of the method according to the present invention is to provide a supply 33 to be incorporated in the reinforcing structure of the papermaking belt of the paper-facing side 51, a machine-facing side 52 of the paper-facing side 51 of the counter 39 and the side of the pore.

il

As mentioned above, the reinforcing structure 33 is an element around which the papermaking belt 10 is formed. Any of the reinforcing structures described in the previous section of this specification may be used. The reinforcing structure 33 is preferably a woven multilayer fabric shown in Figs. 6-11, characterized by warp yarns that are vertically directly superimposed.

Since the preferred papermaking belt 10 is in the form of an endless belt, the reinforcing structure 33 should also be an endless belt, since the papermaking belt 10 is formed around the reinforcing structure 33. As illustrated in Figure 25, the reinforcing structure 33 is arranged so that it extends in the direction of the arrow D around the return roll 78a up, the forming unit 71 and around return rolls 78b and 78c. It is to be understood that the apparatus used to make the papermaking belt of the present invention includes conventional guide rollers, return rollers, drive devices, support rollers, and the like, which are not shown in Fig. 25.

The third stage

The third step of the method of the present invention is to contact at least a portion of the reinforcing structure 33 on the machine side with the working surface 72 of the forming unit 71 (or more specifically, in the case of the illuminated embodiment, conveying the reinforcing structure 33 over the working surface 72 of the forming unit 71).

As mentioned above, it is preferable to use a barrier film 76 to keep the working surface 72 of the forming unit 71 free of resin 70. In this case, in the third step at least a portion 52 of the reinforcing structure 33 facing the machine is contacted with the barrier film so that the barrier film 76 comes between the reinforcing structure 33 and the forming unit 71. .

The particular manner in which the reinforcing structure 33 is positioned relative to either the work surface of the forming unit 71 or the barrier film 76 depends on the particular design of the papermaking belt 10 desired. The reinforcing structure 33 can be placed in direct contact with the barrier film 76. Alternatively, the reinforcing structure 33 may be spaced a certain distance from the barrier film 76. Any suitable means may be used to disengage the reinforcing structure 33 from the barrier film 76. For example, a liquid photosensitive resin 70 could be applied to the machine-facing side 52 of the reinforcing structure 33 so that a portion of the coating is between the reinforcing structure 33 and the work surface 72 of the forming unit 71. However, it is preferred to bring at least a part of the machine per 33 on behalf of the reinforcing structure 52 (e.g., the machine side knuckles) directly in contact with the forming unit 71 with the working surface 72 (or the barrier film 76, if used). Other parts of the reinforcing structure 33, such as the raised portions 120, are detached from the working surface 72 of the forming unit 71.

The fourth step

The fourth step in the method is to apply a liquid photosensitive resin coating 70 to at least one side of the reinforcing structure 33.

The coating 70 is generally applied in such a way that the coating 70 substantially fills the pore areas 39a of the reinforcing structure 33 (the pore areas are defined below). The coating 70 is also applied in such a way that it forms a first surface 34 'and a second surface 35'. The coating 70 is distributed in such a way that at least a part of the second surface 35 'of the coating 70 is located against the working surface 72 of the forming unit 71. The coating 70 is distributed in such a way that the paper-facing side 51 of the reinforcing structure 33 is located between the first and second surfaces 34 'and 35' of the coating 70. Coating the part, disposed between the first surface 34 'and each of 33 paper side reinforcing structure 51 forms a resinous overburden t_o'. At least a portion of the coating 70 penetrates the texture of the work surface 72 of the forming unit 71 (in the direction indicated by the arrows in Figures 28 and 31) so that the textured surface defines areas of the second surface 35 'of the coating 70. Photosensitive resins suitable for coating the reinforcing structure 33 are easy to select from many commercially available resins. Resins that can be used are materials, usually polymers, that cure or crosslink under the influence of radiation, usually ultraviolet (UV) light. Publications containing more information on liquid photosensitive resins include the following: Green et al., Photocross-linkable Resin Systems, J. Macro-Sci. Revs. Macro Chem. C21 (2) (1981-82) 187-273; Bayer, A Review of Ultraviolet Curing Technology, Pin Paper Synthetics Conf. Proc., September 25-27, 1978, p. 167 - 172; Schmidle, Ultraviolet Curable Flexible Coatings, J. of Coated Fabrics 8 (July 1978) 10 - 20. All of the above three publications are incorporated herein by reference. Particularly preferred liquid photosensitive resins belong to the Merigraph resin series manufactured by Hercules Incorporated, Wilmington, Delaware. One of the most preferred resins is Merigraph resin EPD 1616.

In a preferred method of carrying out the present invention, antioxidants are added to the resin to protect the finished papermaking belt 10 from oxidation and to extend the life of the papermaking belt. Any suitable antioxidants can be added to the resin. Preferred antioxidants are Cyanox 1790, marketed by American Cyanamid, Wayne, New Jersey 17470, and Iraganox 1010, manufactured by Ciba Geigy, Ardsley, New York 10502. In a preferred method of making the papermaking belt 10 of the present invention, both antioxidants are added to the resin. The following amounts of antioxidants are added: Cyanox 1790 1/10,%; Iraganox 1010 8/10, 1%. Both antioxidants92 are added to protect the papermaking belt of this invention from a variety of oxidant species.

Any method of applying a liquid material to the reinforcing structure 33 is suitable for applying the coating 70. As shown in Fig. 25, in the preferred method for carrying out the present invention, the liquid photosensitive resin is applied to the reinforcing structure 33 in two steps. The first step is performed at the location 79 indicated by the extruder mouthpiece. The first step is called the pre-filling step because it is performed before the part of the reinforcing structure 33 to be coated is brought into contact with the working surface 72 of the forming unit 71. In this first step, the first liquid photosensitive resin coating is applied to at least the machine-facing side 52 of the reinforcing structure 33 by the extruder mouthpiece 79 so that the pore areas 39a of the reinforcing structure 33 are at least partially filled. The first coating preferably fills the pore areas 39a of the reinforcing structure 33 substantially completely. The pore areas are best seen in Figure 22D. As used herein, the term void areas (or void volume) of the reinforcing means 33 of all the open spaces of the structure that the paper of the reinforcing structure toward the plane defined by the side P_kl and the plane defined by the machine-facing side of the reinforcing structure P_k2 (i.e., spaces between said planes that are not occupied by the reinforcing component 40). The pore spaces 39a thus comprise the pores 39a and any other planes P_kl and P_k2 open spaces in between.

Applying the resin 70 to the extruder mouthpiece 79 is associated with applying a second liquid photosensitive resin coating 70 in a second step by a nozzle 80 located near the point where the mask 74 is fed into the system. Nozzle 80 is applied to another

II liquid photosensitive resin coating 70 on the paper side 51 of the reinforcing structure 33. It is necessary to spread the liquid photosensitive resin 70 evenly over the entire width of the reinforcing structure 33 and force the required amount of material through the pores 39 to completely fill the pores 39a of the reinforcing structure 33. The second coating is applied such that the first coating, together with the second coating, forms a single coating, a coating 70 having the first surface 34 'and the second surface 35' described above and distributed as described above. Thus, this one coating 70 is distributed in such a way that at least a part of the second surface 35 'of the coating is located against the working surface 72 of the forming unit 71; the paper-facing side 51 of the reinforcing structure is located between the first surface 34 'and the second surface 35' of the coating; the part of the coating which is positioned between the first surface 34 'and the reinforcing structure 33 of the paper-facing side 51 forms a resinous overburden t_o'and at least a portion of the coating penetrates the texture of the work surface of the forming unit 71 so that the textured surface defines areas of the second surface 35' of the coating.

It can be seen from the drawings that the steps of applying the liquid photosensitive resin 70 to the reinforcing structure 33 may not always occur in time immediately after the third step described above. This means that the coating (first stage coating) is carried out before luj per 33 products ittavan the structure of the side 52 being brought into contact 72 with the forming unit 71 of the work surface and, after that, if you look at any specific part of the reinforcing structure 33 which extends return roll of the reinforcing structure 78a and around the forming unit 71 towards. On the other hand, looking at the device assembly shown in Figure 25 as a whole, it is apparent that at least a portion of the endless belt comprising the reinforcing structure 33 would generally contact the machining surface 72 of the forming unit 71 before any reinforcement of the reinforcing structure 33 occurs. However, as described herein, the method is generally viewed from the former perspective.

In the embodiment shown in the drawings, the second step (i.e., the backfill step) of applying the photosensitive resin occurs after the point at which the reinforcing structure 33 first comes into contact with the forming unit 71 as it passes around the return rollers of the reinforcing structure. It should be understood that these two events (i.e. application of the coating and contacting the reinforcing structure 33 with the working surface 72 of the forming unit 71) could also be simultaneous or the photosensitive resin could be applied to the upper surface of the reinforcing structure (i.e. on the paper side 51) before the reinforcing structure 33 is first contacted with the forming unit 71. It is intended that the method of this invention include all configurations and sequences of the basic steps described herein. However, the coating of the reinforcing structure 33 preferably takes place in the order shown in the drawings.

As shown in 28, the resin pattern (in principle from the back side of the coating) is forced deployable 33 on the upper surface of the reinforcing filler in the second stage of the structure of the textured surface of the resin 94 in the indicated locations. This resin displaces the air in these valleys, i.e. the recesses. When the steps described below are carried out, the papermaking belt has a texture on the back side that is roughly a mirror image of the texture of the casting surface.

Il

The fifth step

The fifth step of the method of the present invention is the overload t of the resin coating 70_o'thickness adjustment to a preselected value. In the preferred embodiment of the belt manufacturing apparatus shown in the drawings, this step takes place approximately at the same time, i.e. simultaneously, with the second step of applying the liquid photosensitive resin coating to the reinforcing structure 33.

The preselected value of the overload thickness corresponds to the desired thickness of the papermaking belt 10. This thickness also naturally depends on the expected use of the papermaking belt. When the papermaking belt 10 is to be used in the papermaking process described below, it is preferable that the thickness t of the papermaking belt 10 is about 0.01 to 3.0 mm. Other applications may, of course, require thicker papermaking belts, which may be 3 cm or more thick.

Any suitable means for adjusting the thickness can be used. The illustrated means for adjusting the thickness of the overload in Fig. 22 is to use a leaving roller 81, which also acts as a mask guide roller. The distance between the leaving roller 81 and the forming unit 71 can be adjusted mechanically by any conventional means not shown. The leaving roller 81 has a mask 74 and a mask guide roller

82 in connection with which there is a tendency to smooth the surface of the liquid photosensitive resin 70 and to adjust its thickness.

The sixth step

The sixth step of the method of the present invention can be considered as either a single step or two successive steps comprising (1) providing a mask 74 with opaque areas 74a and transparent areas 74b, wherein the opaque areas 74a together with the transparent areas 74b define a preselected and (2) interposing a mask 74 si35 between the liquid photosensitive resin coating 70 and the actinic light source 73, that the mask 74 is in contact with the first surface 34 'of the liquid photosensitive resin coating 70. The mask 74 can be positioned so as to be spaced a certain distance from the first surface 34 'of the coating 70. However, for the reasons described below, it is preferably in contact with the first surface 34 'of the coating 70.

The purpose of the mask 74 is to protect, i.e., shade, certain areas of the liquid photosensitive resin 70 from exposure to light from an actinic light source. If certain areas are shaded, the natural consequence is that certain areas are not shaded and the liquid photosensitive resin 70 in said unshaded areas is subsequently exposed to activating light and cures. When the steps described herein are performed, the shaded areas normally comprise a preselected pattern formed by channels 36 in the cured resin lattice 32.

The mask 74 may be made of any suitable material that may be provided with opaque areas 74a and transparent areas 74b. The flexible photographic film-like material is suitable for use as a mask 74. The flexible film may be polyester, polyethylene, or cellulose or other suitable material. The opaque regions 74b should be opaque to the curing light of the photosensitive liquid resin. In the case of the preferred liquid photosensitive used herein, the opaque regions 74a should be opaque to light having a wavelength of about 200 to 400 nm. The opaque areas 74a can be provided to the mask 74 by any suitable means, such as blue copying (i.e., frontalide methods) or photographic, gravure, flexographic, or rotary screen printing methods. The opaque areas 74b of the mother are preferably incorporated into the mask by the blue copy method (i.e., the frontalide method).

The mask 74 may be an endless loop (details of which are conventional and therefore not shown) or may be fed from the feed roll transversely through the system to the take-up roll, neither of which is shown in the figure, as they are also conventional. The mask 74 travels in the direction indicated by directional arrow D3, turns under nip roll 81 where it is brought into contact with the liquid VA10 lonherkän resin with the surface 70, and then passes through a mask 82 in the vicinity of which it is removed from contact with the resin 70. In this particular embodiment, the thickness adjustment of the resin 70 and the placement of the mask 74 occur simultaneously.

The seventh step

The seventh step of the method of the present invention comprises curing the liquid photosensitive resin coating in areas left unshaded by the transparent areas 74b of the mask 74 and leaving the shaded portions uncured by exposing the liquid photosensitive resin coating 70 through a mask having a .

In the embodiment illustrated in Figure 25, the barrier film

76, the reinforcing structure 33, the liquid photosensitive resin, and the mask all form a unit that runs as a whole from the discharge roller 81 to the vicinity of the mask guide roller 82. Between the leaving roll 81 and the mask guide roll 82, and at the point where the barrier film 76 and the reinforcing structure 33 are still against the forming unit 71, the liquid photosensitive resin 70 is treated with light having an activating wavelength and supplied from the exposure lamp 73.

The exposure lamp 73 is generally selected to provide illumination in the wavelength range that is principally caused by the curing of the liquid photosensitive resin 70. This wavelength is one of the characteristic properties of the liquid photosensitive resin 70. Any suitable light source, such as mercury arc, pulse xenon, electrodeless and fluorescent lamps, can be used. As described above, when a liquid photosensitive resin is treated with light of a suitable wavelength, curing is initiated in the exposed areas of the resin 70. Curing usually manifests as solidification of the resin in exposed areas. Unexposed areas, on the other hand, remain fluid.

In addition to initiating curing of the photosensitive liquid resin 70 in areas which are unshaded due to the transparent areas 74b of the mask 74, treatment of the photosensitive resin coating 70 with light having an activating wavelength also initiates curing of the portions of the liquid photosensitive resin unshaded due to the transparent areas 74b of the mask 74, as will be seen in connection with the description of the following figures. These parts then harden to the shape determined by the surface texture formed by the work surface of the forming unit. These curing modes of said parts forming the passageways and surface texture irregularities 32 of the second resinous surface 35 in the backside network 35a.

The intensity of the exposure and its duration depend on the degree of curing required in the exposed areas. The absolute values ​​of the exposure intensity and time depend on the chemical nature of the resin, its light properties, the thickness of the resin coating and the pattern chosen. For the preferred resin, Merigraph EPD 1616, this amount is in the range of approximately 100 to 1,000 mJ / cm² the preferred range being about 300 to 800 mJ / cm²and the most preferred range is about 500 to 800 mJ / cm².

Il

The exposure intensity and the angle of incidence of light have an important effect on the presence or absence of slope in the walls 44 of the channels 36. In addition to the effect of exposure intensity and angle of incidence on the walls 44 of channels 36, they affect the air permeability of the cured lattice 32. Air permeability (air permeability) is important for the use of the papermaking belt of this invention in papermaking processes in which blow drying is performed. It will be appreciated that if the degree of collimation of the activating light of the wavelength is high, the walls 44 of the channels 36 will be less inclined. Less inclined (i.e., closer to vertical) duct walls give the papermaking belt higher air permeability than inwardly inclined walls (with the knee area of ​​the first surface defined) because the total area of ​​the papermaking belt through which air can flow is greater when the walls 44 of the channels 36 are not. sloping inwards.

In a preferred embodiment of the present invention, the angle of incidence of light is collimated to cure the photosensitive resin in more desired areas and to provide the desired angle of inclination in the walls of the finished papermaking belt 44. Other means of view mirrors). In a preferred embodiment of the present invention, a subtractive collimator (i.e., an angle distribution filter or a collimator that filters or blocks UV light rays in non-desired directions) is used. Any suitable device can be used as the subtractive collimator. A dark, preferably black, metal device shaped as a series of channels through which light directed in a desired direction can pass is preferred. In a preferred embodiment of the present invention, the collimator has dimensions such that

100 that it transmits light such that the projection of the surface of the cured resin web is 35% above the papermaking belt and 65% at the back.

The eighth step

The eighth step in the method of the present invention is the removal of substantially all of the uncured liquid photosensitive resin from the partially formed composite belt 10 ', leaving a cured resin grid 32 around at least a portion of the reinforcing structure 33.

At this point, the light-shielded resin is removed from the partially formed composite belt 10 'as described below to provide a grid 32 with a plurality of channels 36 in areas shaded by light opaque areas 74a of the mask 74 and light paths 37 forming a surface texture irregularity. the backside network 35a points, wherein the second surface 35 'of the coating has penetrated the texture of the work surface 72 of the forming unit 71.

In the embodiment shown in Figure 25, at a location near the mask guide roller 82, the mask 74 and barrier film 76 are physically separated from a partially formed composite belt 10 'comprising a reinforcing structure 33 and now a partially cured resin 70 and a certain amount of uncured resin. The composite formed by the reinforcing structure 33 and the partially cured resin 70 passes into the region of the first resin removal shoe 83a. A vacuum is applied to the second surface of the composite belt 10 'at the first resin removal shoe 83a so that a substantial amount of uncured liquid photosensitive resin exits the composite belt 10'.

As it advances, the composite belt 10 'enters the resin wash jet 84 and the resin wash station drain 85, where the composite belt 10' is thoroughly washed with water or other suitable liquid.

101 to remove substantially all of the remaining uncured liquid photosensitive resin which is removed from the system through the resin washing station drain 85. At the second resin removal shoe 83b, any remaining washing liquid and uncured liquid resin are removed from the composite belt 10 'using a vacuum. At this point, the composite belt 10 'comprises a reinforcing structure 33 and an associated cured resin lattice 32 and represents the papermaking belt 10 which is the product of this method.

As shown in Figure 25, a second treatment of the resin with activating light (hereinafter sometimes referred to as the post-curing step) may optionally, and preferably, be performed to complete the curing of the resin and to improve the hardness and durability of the cured resin lattice 32. The post-curing step occurs at the location indicated by reference to the following Figure 26. Figure 26 is an enlarged schematic representation of this post-curing step.

As shown in Fig. 26, the composite belt 10 'is exposed a second time with light having an activating wavelength using a post-curing UV light source 73a. However, this second exposure occurs when the composite belt 10 'is submerged under water 86. To immerse the composite belt 10 ', the composite belt 10' is deflected somewhat from the path it has traveled, as shown in Figure 26, by rollers 87a, 87b, 87c and 87d in the water 86 of the water bath 88. It has been found that it is important for the composite belt 10 'to be embedded in connection with this post-curing exposure; the finished strap 10 is otherwise too sticky or sticky. In addition, it has been found necessary to add sodium sulphite (NA₂SO₃) to remove dissolved oxygen from the water as much as possible to facilitate complete polymerization of the resin. Sodium sulfite is added to up to about 2% by weight of the water in the post-curing bath 88.

102

Fig. 26 further shows that in this post-curing, a mirror 89 is placed on the bottom surface 90 of the water bath 88. The function of the mirror is to reflect UV light coming back to the mirror 89 back below the composite belt 10 ', i.e. the back side 12. This step is particularly important to completely cure the resin portion the second surface 32 of the papermaking belt 35 of the framework 10 in the backside network 35a. As shown in the previous figure, all UV light is supplied from sources located above the top surface of the composite belt 10 '. In this case, too, the amount of UV light supplied during this post-curing depends on the resin in question as well as the desired curing depth and pattern. In the case of the preferred resin, Merigraph resin EPD 1616, the dosages defined above in connection with the pre-curing step are also suitable for the post-curing step. However, it is not necessary to collimate the light in the post-curing step because the channels are already suitably formed in the lattice.

The process is continued until the reinforcing structure 33 has been treated along its entire length and converted into a papermaking belt 10.

If it is desired to form a papermaking belt with different patterns superimposed or patterns of different thicknesses, the reinforcing structure can be passed through the process several times. Several exports through the process of this invention can also be used to form relatively thick papermaking belts.

3. Papermaking Process

The following describes a papermaking process utilizing the improved papermaking belt 10 of the present invention, although it is contemplated that other methods may be used to make the paper products described herein. As a background, a method of making a paper that does not contain this il

103 improvements in the method and without the use of the improved papermaking belt 10 of the present invention are described in detail in U.S. Patent 4,529,480 (Tissue Paper, Paul, D. Trokhan, issued July 16, 2006).

1985). The Trokhan patent is incorporated herein by reference to the extent that it is consistent with this description. The following are improvements to the method described in the Trokhan patent.

The overall papermaking process using the papermaking belts of the present invention comprises a series of steps or operations that generally occur in the chronological order set forth below. The following chapters discuss each step in detail with reference to Figure 1. It is to be understood, however, that the steps described below are intended to assist the reader in understanding the method of the present invention and that the invention is not limited to methods having only a predetermined number of steps or a specified step arrangement. In this respect, it is noted that it is possible to combine the following steps so that they are carried out simultaneously. It is also possible to divide the following steps into two or more steps without departing from the scope of the present invention.

Figure 1 is a simplified schematic representation of one embodiment of a continuous paper machine useful in practicing the papermaking process of the present invention. The papermaking belt 10 of the present invention is shown in the form of an endless belt. The specific paper machine illustrated in Figure 1 is a flat wire machine that is generally similar in structure and belt arrangement to the paper machine disclosed in U.S. Patent 3,301,746 (Sanford and Sisson, January 31, 1967), which is incorporated herein by reference.

104

It is also contemplated that a twin wire paper machine illustrated in Figure 1 of U.S. Patent 4,102,737 (Morton, July 25, 1978), which is incorporated herein by reference, could be used to practice the present invention. If the twin wire paper machine disclosed in U.S. Patent No. 4,102,737 (Morton) is used to practice the present invention, the papermaking belt of the present invention would replace the drying-heel press fabric represented by No. 4 in the drawings of the Morton patent. However, all other references to the drawings refer to the drawings appended to this specification.

First phase

The first step in carrying out the papermaking process of this invention is to provide a water dispersion 14 of paper fibers.

An apparatus for preparing an aqueous dispersion 14 of paper fibers is well known and is therefore not shown in Figure 1. The aqueous dispersion 14 of paper fibers is placed in a headbox 13. Figure 1 shows one headbox. However, it is to be understood that there may be multiple headboxes in alternative arrangements of the papermaking process of this invention. The headbox or headboxes and apparatus for preparing an aqueous dispersion of paper fibers are preferably of the type disclosed in U.S. Patent 25 Publication 3,994,771 (Morgan and Rich, November 30, 1976), which is incorporated herein by reference. The preparation of the aqueous dispersion and the characteristic properties of the aqueous dispersion are described in more detail in U.S. Patent 4,529,480 (Trokhan, July 16, 1985), which is incorporated herein by reference.

The aqueous slurry 14 of paper fibers fed from the headbox 13 is applied to a forming belt, such as a flat wire 15, to carry out the second stage of the papermaking process. The flat wire 15 is supported by a chest roll 16 and a plurality of return rollers, denoted by the numbers 17 and 17a. Tasoviiil

105 RAA 15 is rotated in the arrow A direction indicated by a conventional drive means which is not shown in Figure 1. The paper machine shown in Figure 1 may also be associated auxiliary units and devices which are commonly associated with pape5 rikoneisiin and linear screens, including forming boards, hydrofoils, vacuum boxes, tension, support rolls, wire cleaning showers etc., which are conventional and are therefore omitted from Figure 1.

Second phase

The second step of the papermaking process is to form a paper fiber primary web 18 on the porous surface from the aqueous dispersion 14 fed in the first step. The flat wire 15 acts as a porous surface in the paper machine shown in Figure 1. As used herein, a primary web is a fibrous web that is rearranged on a papermaking belt in accordance with the present invention during the papermaking process.

The characteristics of the elementary web 18 and various possible methods for forming the elementary web 18 are described in U.S. Patent 4,529,480, which is incorporated herein by reference. In the process shown in Figure 1, the elementary web 18 is formed from an aqueous dispersion 14 of paper fibers between a breast roll 16 and a return roll 17 by depositing an aqueous dispersion 14 on a flat wire 15 and removing a portion of the aqueous dispersing medium. Conventional suction boxes, chests, discharge strips, etc., not shown in Figure 1, are useful for removing water from the aqueous dispersion 14.

Once the elementary web 18 is formed, it passes with the plane 30 around the wire 15 around the return roll 17 and is brought in the vicinity of the second papermaking belt 10, the papermaking belt 10 of the present invention.

The third stage

The third step in the papermaking process is to contact (i.e., bond together) the web 35

106 with in contact with the papermaking belt of the present invention 10 in the paper side 11.

The purpose of this third step is to bring the embryonic web 18 into contact with the papermaking belt 10 PA5 initially in contact with the p with uolen, for which the embryonic web 18 and the individual fibers therein are then deflected, rearranged, and further dewatered. The elementary web 18 is brought into contact with the papermaking belt 10 of the present invention by means of a planar line 15. The planar wire 15 contacts the primary web 18 with the papermaking belt 10 of the present invention and transfers the primary web 18 to this belt at the vacuum catcher 24a.

shown in Figure 1, the papermaking belt of the non keksin15 10 travels in the direction of arrow B. The papermaking belt 10 ribs the papermaking belt return rollers 19a and 19b, the printing roll 20, the papermaking belt return rollers 19c, 19d,

19e and 19f and around the emulsion application roller 21 (which applies the emulsion 22 to the papermaking belt 10 from the emulsion bath 23). The loop rotated by the papermaking belt 10 of the present invention also includes means for applying a liquid pressure difference to the paper web, which in a preferred embodiment of the present invention comprises a vacuum catch 24a and a suction box such as a multi-slit suction box 24. There is also a pre-dryer 26. Between the papermaking belt return rollers 19c and 19d and also between the papermaking belt return rollers 19d and 19e, there are further water jets 102 and 102a, respectively. water jets

102 and 102a are for cleaning the papermaking belt 10 from any papermaking fibers, adhesives, etc. that are trapped in the portion of the papermaking belt 10 that has passed through the final step of the papermaking process. The papermaking belt 10 of the present invention also has a waste space associated with FIG

107 additional support rollers, return rollers, cleaning utensils, actuators, etc., commonly used in paper machines and well known to those skilled in the art.

The operation of the emulsion application roller 21 and the emulsion bath 23 is discussed in connection with the third step for convenience. The emulsion application roller 21 and the emulsion bath 23 continuously apply an effective amount of chemical compounds (or compounds) to the belt 10 during the papermaking process. The chemical compounds can be applied to the fabrication belt 10 at any stage during the papermaking process, although it is preferred to add chemicals to the paper-contacting side 11 of the belt 10 at a point in the belt cycle where the belt 10 does not support the paper web. This normally occurs (as described in more detail below) after the pre-dried paper web 27 has been transferred from the papermaking belt 10 to the surface of the Yankee cylinder 28 and the belt 10 is returning to contact with the second primary web 18 (i.e., at the emulsion application roll 21).

One or more chemical compounds are applied to the papermaking belt 10, preferably in the form of an emulsion, such as the emulsion 22 shown in Figure 1. These one or more compounds have the following two functions: (1) to act as a release agent or release emulsion (a coating on a papermaking belt according to the present invention so that the paper detaches from the belt and does not stick to it when the papermaking process steps are performed on the paper web); (2) treating the belt to extend its service life by reducing the resilience of the resin lattice 32 due to oxidation decomposition (i.e., the emulsion 22 also acts as an antioxidant). One or more chemical compounds are preferably applied uniformly to the paper-contacting side 11 of the belt 10 so that the paper-contacting side 11 benefits substantially the entire area from the chemical treatment.

108

The preferred emulsion 22 consists essentially of five compounds, although it is contemplated that suitable substitutes or additional compounds could be used. The preferred composition contains water, a high power turbine oil known as Regal Oil, dimethyl distearyl ammonium chloride, cetyl alcohol and an antioxidant.

As used herein, the term Regal Oil means a blend of about 87% saturated hydrocarbons and about 12.6% aromatic hydrocarbons and very small amounts of additives, manufactured by Texaco Oil Company, Houston, Texas, under part number R&O 68 Code 702. Purpose of Regal Oil the composition described above is to provide an emulsion having properties that allow it to function as a release agent.

Dimethyldistearylammonium chloride is sold by Sherex

Chemical Company, Inc., Rolling Meadows, Illinois, under the tradename ADOGEN TA 100. Hereinafter, dimethyldistearylammonium chloride is referred to as ADOGEN for convenience. ADOGEN is used in an emulsion to emulsify or stabilize oil particles of a surfactant (Regal Oil) in water. As used herein, the term surfactant means a surfactant having one end hydrophilic and the other end hydrophobic and extending at the boundary between the hydrophilic agent and the hydrophobic agent to stabilize the two.

As used herein, cetyl alcohol means linear C₁₆fatty alcohol. Cetyl alcohol is manufactured by The Procter & Gamble Company, Cincinnati, Ohio. Like ADOGEN, acetyl alcohol is used as a surfactant in the emulsion used in this invention.

As used herein, the term antioxidant means a compound that, when applied to a surface prone to oxidation of an article, reduces the tendency of the article to oxidize (i.e., coalesce with oxygen). In particular, in this specification, the term antioxidant means compounds that reduce II

109 the tendency of the cured resin network of the papermaking belt 10 of the present invention to oxidize. One preferred antioxidant is Cyanox 1790 sold by American Cyanamid, Wayne, New Jersey 07470.

The relative proportions of the compounds used in the emulsion are shown in the following table:

<td>Component</td><td>Volume (1)</td><td>Weight (kg)</td>

<td>Water</td><td> 1961</td><td> 1959,51</td>

<td>Regal Oil</td><td> 208</td><td> 190,96</td>

<td>ADOGEN</td><td>AS*</td><td> 10,9</td>

<td>cetyl alcohol</td><td>AS*</td><td> 7,3</td>

<td>Cyanox 1790</td><td>AS*</td><td> 2,63</td>

N / A * - The component is added in solid form.

The fourth step

In the fourth step of the papermaking process, the liquid pressure difference of the suitable fluid is directed to the elementary web 18 by a vacuum source to direct at least a portion of the elementary web 18 paper fibers into channels 36 of the papermaking belt 10 and remove water from the elementary web 18 fibers into the desired structure.

A preferred method of achieving a liquid pressure difference is, as also more fully described herein, to position the elementary web 18 in such a way that the web is subjected to a vacuum through the channels 36 by directing the vacuum from the back side 12 of the papermaking belt 10 of the present invention. In Figure 1, this preferred method is illustrated by the use of a vacuum trap 24a and a multi-slot suction box 24. Preferably, a vacuum pressure of about 27.09 to 40.64 kPa is used in the vacuum catch 24a

110 and in a multi-slit suction box, 24 suction pressures of about 50.8 to 67.7 kPa. Thus, in a preferred embodiment of the method of the invention, the liquid pressure difference is typically a negative pressure (i.e., below normal pressure) and the suitable fluid is air. Alternatively or in addition, a positive pressure in the form of air or water vapor pressure may be directed through the flat wire 15 to the elementary web 18 at the catch 24a or the suction box 24. The means for directing such a positive pressure are conventional and are therefore not shown in Figure 1.

Figures 1A and 1B illustrate the guide of the fibers into the channels 36. Figure 1A is a simplified cross-sectional view of a portion of the papermaking belt 10 and the primary web 18 when the primary web 18 is introduced into the papermaking belt.

10 but before directing the fibers into the channels 36.

As shown in Figure 1A, the elementary web 18 is still in contact with the flat wire 15 (or more specifically between the flat wire 15 and the papermaking belt 10 of the present invention). Figure IA shows only one channel 36 and the embryonic web 18 is shown associated with the papermaking belt 10 of the framework 32 of the paper side network surface 34a.

The portion of the papermaking belt shown in Figures 1A and 1B has been simplified by omitting the reinforcing structure generally part of the preferred embodiment of the papermaking belt of the present invention, and also showing the walls of the channels 36 in straight vertical lines in a cross-sectional view. more complex. In addition, the opening of the channel 36 in the first surface 34, the first channel opening 42, and the opening in its second surface 35, the second channel opening 43, are shown to be approximately the same size and shape as in the preferred embodiment 35 of the present invention.

II

The channel openings III are smaller than the channel openings in the first surface 34.

Fig. 1B is a simplified cross-sectional view of a portion of the papermaking belt 10, similar to Fig. 1A. Figure IB shows that a substantial portion of the fibers in the embryonic web 18 itself, and hence the embryonic web 18 is transferred to the channel 36 of the paper side network surface 34a below, to form an intermediate web 25. The rearrangement (not shown) of the individual fibers of the primary web 18 occurs during guidance.

Fig. 1B also shows that in the step where the fibers in the core web 18 are guided into the channel 36 and rearranged, the primary web 18 is no longer in contact with the flat wire 15. As shown in Figure 1, the web 18 is separated from the flat wire 15 immediately after leaving the catch 24a.

Either at the time the fibers are directed to the channels 36, or after such guidance, water is removed from the primary web 18 through the channels 36. Dewatering takes place due to the difference in fluid pressure. It is important, however, that an essential part of water removal from the embryonic web does not occur until kuitu25 of the guiding channels 36. As an aid in achieving this condition is that at least the paper side network 34a surrounded by channels 36, are generally isolated from each other. This isolation or partitioning of the channels 36 is important to ensure that the guiding force, such as the vacuum, is directed relatively abruptly and is used to a sufficient extent to guide the fibers. This has to be compared to the situation where the channels 36 are not isolated. In this latter situation, the vacuum penetrates the adjacent channels 36, resulting in a gradual effect of the vacuum and removal of water without associated fiber diversion.

In the machine illustrated in Fig. 1, dewatering takes place initially at the catch 24a and the suction box 24. Because the channels 36 are open through the papermaking belt in its thickness direction, the water exiting the primary web 18 passes through the channels 36 and out of the system. The dewatering continues until the consistency of the web associated with the channels 36 increases to approximately 20-35%.

The fifth step

The fifth step is to transport the papermaking belt 10 and the elementary web 18 over the vacuum source described in the fourth step. The fifth step is preferably carried out when the fourth step takes place. The belt 10 conveys the elementary web 15 on its side in contact with the paper 11 over the vacuum source. At least a portion of the textured backside 12 of the belt 10 is generally in contact with the surface of the vacuum source as the belt 10 passes over the vacuum source.

The step of the papermaking belt 10 of the present invention passing over a vacuum source reduces the undesired accumulation of paper fibers at the edges of the suction box. Without wishing to be bound by any particular theory, it is believed that one of the critical factors in achieving this reduction in the method of the present invention is the control of the relative abruptness of steering during the preceding step. Deflection of the fibers is controlled by using a papermaking belt which has a textured backside 12. The textured backside surface to let a certain amount of air to flow in paperinvalmis30 tushihnan 10 across the backside 12 when the backside 12 is in contact with the pickup shoe 124a and the suction box 24 surfaces. The belt 10 in the backside network 35a is the passageways 37 that provide a space through which at least a portion of this air can flow in. This has to be compared to the previous steering part, which was equipped with a relative

II

113 on a flat bottom surface. The flat surface tended to form a barrier to the suction box used to guide the fibers of the elementary web, resulting in an extremely sudden effect of the suction pressure when the barrier opened. Thus, the control of the deflection of the fibers of the elementary web 18 may be a step which occurs naturally in connection with the fifth step, or it may be considered as a separate step.

It is also assumed that these passageways 37, which form surface texture irregularities 38 on the back side 12 of the papermaking belt 10, have the effect of cleaning the edges or surfaces of the vacuum dewatering apparatus used in the papermaking process. This cleaning operation tends to eliminate any undesirable accumulation of paper fibers on this vacuum equipment.

This cleaning effect is assumed to occur when the vacuum source has at least one surface over which the papermaking belt passes during the control step. Thus, the cleaning of the surfaces of the vacuum dewatering equipment may be a step that occurs naturally in connection with the fifth step20, or it may be considered as a separate step. If this step is considered as an additional step, this would involve removing any accumulated on the surface of said vacuum source to said surface with the belt 10. The textured backside 12 of paper fibers on the vacuum source.

After suction pressure has been applied and the papermaking belt 10 and the primary web 18 have passed over the vacuum source, the primary web 18 is in a state where it has been subjected to a fluid pressure difference and guided but has not been completely dewatered, so it is now called intermediate web 25.

The sixth step

The sixth step of the papermaking process is an optional step comprising drying the intermediate web 25 to form a pre-dried paper fiber web. What is ta97070

114 an appropriate method traditionally known in the papermaking industry can be used to dry the intermediate web 25. For example, flow-through dryers, heat-free capillary dewaterers, and Yankee cylinder dryers alone and in combination are satisfactory.

Figure 1 illustrates one preferred method of drying the intermediate web 25. After leaving vacuum box 24, although associated with the papermaking belt 10 of 25 passes around the papermaking belt return roll 19a and travels in the direction of arrow B indicating the direction of the intermediate web. The intermediate web 25 then passes through a possible pre-dryer 26. This pre-dryer 26 may be a conventional flow-through dryer (hot air dryer) well known to those skilled in the art.

The amount of water leaving the pre-dryer 26 is controlled so that the consistency of the pre-dried web 27 leaving the pre-dryer 26 is about 30-98%. The pre-dried web 27, which is still associated with the papermaking belt 10, passes around the return roll 19b of the papermaking belt and passes into the area of ​​the printing waste roll 20.

The seventh step

seventh step in the papermaking process is the 10 paper side network of the papermaking belt of the present invention, printing 34a predried web by interposing the predried web 27 of papermaking belt 10 and the printing surface to form an embossed paper fiber web.

If a possible sixth pre-drying step has not been performed on the intermediate web 25, this seventh step is performed on the intermediate web 25.

The seventh step is carried out in the machine illustrated in Figure 1, when the pre-dried web 27 passes through a gap formed between the weight leaving roll 20 and the Yankee cylinder 28. When the predried web 27 passes through this nip, the network pattern by the paper side network 34a formed paII

115 on the side 11 of the manufacturing belt 10 in contact with the paper, presses into the pre-dried web 27 to form a heel-pressed web 29.

The eighth step

The eighth step of the papermaking process is the drying of the heel-pressed web 29. Embossed web 29 is different from the papermaking belt 10 of the present invention after the paper side network 34a is imprinted web 29 to form a printed web. When the heel-pressed web 29 differs from the papermaking belt 10 of the present invention, it adheres to the surface of the Yankee cylinder 28 to dry it to a consistency of at least about 95%.

The portion of the belt 10 carrying the web passes around the return rollers 19c, 19d, 19e and 19f of the papermaking belt 10 and through jets 102 and 102a placed therebetween, where it is cleaned. From the jets, a portion of this belt passes to an emulsion roll 21 where it receives a new dose of emulsion 22 before coming into contact with the second portion of the elementary web 18.

The ninth stage

The ninth step in the papermaking process is to shorten the dried web (heel-pressed web 29). This ninth step is a possible, but very preferred, step.

As used herein, shortening refers to a reduction in the length of a dry paper web that occurs when energy is directed to the dry web in such a way that the length of the web decreases and the fibers in the web rearrange, resulting in rupture of bonds between the fibers. The shortening can be done in any of a few well-known ways. The most common and preferred method is creping.

In the creping operation, the dried web 29 is attached to the surface and then detached from this surface by a scraper 116. As shown in Fig. 1, the surface to which the web is usually attached also acts as a drying surface. This surface is typically the surface of a Yankee cylinder 28, as shown in Figure 1.

The adhesion of the heeled web 29 to the surface of the Yankee cylinder 28 is facilitated by the use of a creping adhesive. Typical creping adhesives may include any suitable adhesives, such as polyvinyl alcohol based adhesives. Specific examples of suitable adhesives are described in U.S. Patent 3,926,716 (Bates, December 16, 1975), which is incorporated herein by reference. The adhesive is applied either to the pre-dried web 27 immediately prior to passing through the roll slot described above or more preferably to the surface of the Yankee cylinder 28 before the web is pressed against the surface of the Yankee cylinder 28 by the printing roll 20. The adhesive application means and method of applying the present invention are conventional and therefore not shown. . Any method known to those skilled in the art for applying creping adhesives, such as spraying, can be used.

In general, only 29 channels ohjautumattomat web portions that have been attached with the papermaking belt 10 of the paper-contacting side 11 of the paper side network 34, 28 is glued directly to the surface of the Yankee cylinder. The paper side network 34a pattern and the orientation of the scraper 30 will largely determine the amount and nature of the resulting creping the web.

The physical characteristics of the paper web 31 produced by the process of this invention are described in the aforementioned U.S. Patent 4,529,480 (Tissue Paper, Trokhan, July 16, 1985), which is incorporated herein by reference. However, the web area of ​​the paper web and the plurality of domes conform to the linear Idaho pattern in place of the hexagonal pattern shown in the drawings of U.S. Patent 4,529,480.

II

117 due to the different shape of the channels in the preferred embodiment of the papermaking belt 10 according to

The paper web 31, which is a product of the present invention, may optionally be calendered and either re-rolled with or without differential winding or cut and stacked, all operations performed by conventional means not shown in Figure 1. The paper web 31 is then ready for use.

4. test methods

It has been found that belts with a certain amount of backside texture will achieve the desired goals of paper fibers on the surfaces of the vacuum dewatering an undesirable reduction in the accumulation and controlling the other problems associated with the fiber accumulation. The backside teks15 turoinnin number and nature of which must be present in order to achieve the desired results when using the papermaking belt 10 of the present invention, it is a feature of the belt, which is called a belt, or more particularly, a textured backside of the belt surface 12, läpikulkukapasiteetiksi fluids. As used herein, the term fluids throughput means the amount of air (i.e., air leakage) passing through the back surface 12 of the papermaking belt 10 under the conditions of the test developed for this particular purpose described below.

Air leakage across the back surface of the papermaking belt 10 is hereinafter sometimes referred to as XY plane air leakage. The XY expression derives from the fact that if the papermaking belt 10 of the present invention were placed in a rectangular coordinate system so that the backside 12 of the papermaking belt 10 was in the plane formed by the x and y axes, the air leak of interest would be leakage along the backsheet 12 where in any direction in the XY plane.

XY or backside air leakage test utilizes a device which is represented schematically

118 Figures 32 and 33. Figure 32 shows a schematic plan view of the backside leakage testing device 56 of the upper surface. All hoses and pipes generally associated with the test apparatus are omitted from Figure 32 for simplicity. These hoses and tubes are best seen in the side view of the device shown in Figure 33. As shown in these figures, the backside leakage testing device 56 has as its basic components, a stand 57, which includes a first plate 58 having a central opening 59; a smooth circular second plate detached from the rack, which can be placed on the opening 59 in the first plate 58; liquid-filled vacuum gauge · 62 and flow gauge 63.

The plate forming the top of the rack (i.e., the first plate 58) is in its preferred shape a square having dimensions of 20.32 cm x 20.32 cm and a thickness of 1.27 cm. The first plate 58 provides a smooth, deformable, and impermeable to fluids (i.e., gases and liquids) surface. It is preferably made of stainless steel with a mirror-polished and extremely smooth surface. For accurate readings, it is especially important that there are no scratches or other defects on the surface of this disc. Such surface defects allow for additional air leakage, resulting in higher readings than would be obtained if the first plate 58 were free of such defects. The diameter of the opening in the center of this plate is 2.54 cm. In addition, the rack used for the test described herein has a circle engraved on the first plate 58 with a diameter of about 8.89 cm and centered around the opening 59. The purpose of this circle is to act as a guide for centering the second plate 60 over the opening 59. This circle is not expected to affect the accuracy of the readings.

The circular second plate 60, which is not part of the rack, is also made of stainless steel in its preferred form

119 stainless steel, with a diameter of 7.62 cm and a thickness of 1.27 cm. The mass of the second plate 60 is 405 g. The mass must be sufficient to hold the belt sample to be tested on the rack without compressing it unnecessarily.

As shown in Fig. 33, the adapter 61 fits inside the opening 59 in the first plate 58 in such a way that a pipe or hose can be placed in the opening 59 and held in place there. The adapter 61 has a short tube 64 extended at least at one end. This tube

64 extends toward the mouth of the opening 59 on the surface of the first plate 58 on which the portion of the belt to be tested rests. The inner diameter of the tube 64 from the adapter 16 is 0.793 cm.

At one end of the adapter 61, a hose 65a runs to the bottom of the flow meter 63. A flow meter 63 is used to measure the air flow rate through the test portion of the papermaking belt 10. The flowmeter has a numerical scale from 0 to 150. As with most flowmeters, no specific units are marked on the scale. Therefore, the flow meter 63 is calibrated with respect to one of the known units, as described in more detail below. One suitable flowmeter is a meter labeled FM 102-05 manufactured by Cole Parmer Company, Chicago, IL 60648.

Another hose 65b runs from the flow meter 63 s yläpääs25 tube 68 which is ultimately connected to a vacuum source which pulls a vacuum in the direction of arrow V_T direction. The vacuum source itself is conventional and is therefore not shown in Figure 33. The tube 68 running from hose 65b to the vacuum source has a few branches. These branches have a shut-off valve

69a, coarse control valve 69b and fine control valve 69c as well as a liquid-filled vacuum gauge 62 calibrated for a pressure range of 0 to 762 mmHg. Any meter that accurately measures vacuum in millimeters of mercury is suitable. One example of such a vacuum35 is a model marked AIS1 316 Tube &amp; socket

120

Well. 250.2274A, manufactured under the tradename Ashcroft Duragauge, Stratford, CT.

In use, a piece of papermaking belt 10 is placed over an opening 59 in the plate 58 of the XY leak test rack 57. A piece of papermaking belt 10 is placed on the plate with the paper contact side 11 facing up (i.e., away from plate 58) and the back side 12 directly onto plate 58. A piece taken from the papermaking belt 10 should be of sufficient size to be at least larger than the circular second plate 69 in all directions. However, Figures 32 and 33 show only a portion of the papermaking belt piece 10 to illustrate the point. In addition, it should also be noted that the portion of the papermaking belt 10 shown in these figures is greatly exaggerated due to illumination relative to the size of the leak tester 56.

The second plate 60 is then placed on top of the contact with the papermaking belt 10 of the paper side 11 of the belt in place and to maintain the test piece of the papermaking belt 10 to cover the conduits 36 to prevent the air to come through the channels 36. The suction pressure is applied to the sample and the valves 69a, 69b and 69c are adjusted so that the preset value of the pressure difference measured by the vacuum gauge 62 is about 177.8 mmHg. However, the readings have been taken with a preset value of 127 mmHg displayed by the vacuum gauge 62 before the fully standardized procedure is established. Readings taken at 127 mmHg can be converted to readings taken at 177.8 mmHg by fitting the readings taken at 127 mmHg to the following equation, where x is the reading taken at 127 mmHg and y is the corresponding reading at 177 mmHg:

y = 2.6720 + 1.233x

When the suction pressure is thus applied to the sample, a direct reading is taken with a flow meter 63.

II

121 directly read a measure of the XY plane discharge portion 10 of the papermaking belt 12 across the backside and, more particularly defined in the second plate 60 around the periphery (as the direction indicated by arrows L) and finish of the test paperin5 manufacturing belt 10 backside 12 of the cross flowing air volume. This unit of reading has been named marlatt according to Henry Marlatt, Mehoopany, Pennsylvania, who is the person responsible for taking some air leak readings using the tes10 described above. Marlats can be converted to standard cubic centimeters per minute by placing the reading measured in marlates in the following equation, where x is the reading in marlates and y is the corresponding value in standard cubic centimeters per minute:

y = 36.085 + 52.583x - 0.07685x².

This equation for converting marlats to standard cubic centimeters per minute was developed by calibrating the flow meter to cm³/ min (NTP) using Buck

Optical Soap Bubble Meter. The relationship between the readings taken directly in marathes by the flow meter 63 and the corresponding standard cubic centimeter / min reading is shown graphically in Figure 34.

The flow-through capacity of the fluids (i.e. the amount of air leakage measured by the test described above) should not be less than about 35 marlats [about 1,800 cm³/ min (NTP)]. Belts with a fluid throughput of 35 marlats are beginning to achieve some of the benefits of reducing the accumulation of paper fibers in the vacuum dewatering equipment used in the papermaking process. In other words, the grid 32 in the second surface of the passageways 37 should be together with other elements forming the backside texture of a size sufficient to päästääkeen or capacity of at least about 1 800 cm³/ min (NTP) air or other run97070

122 VAA material to pass (i.e., escape) across the belt textured backside surface of the belt 10. The back side 12 is placed in contact with the flat, nondeformable, fluid-impervious surface and the channels 36 are covered, so as to prevent the air or fluid from escaping from the channels 36 through and the belt 10 with the reverse side a fluid pressure difference of about 17.78 mmHg less than normal pressure is applied.

The amount of air leakage that occurs in papermaking belts that function acceptably in the papermaking process is generally greater than about 40 marlats [about 2,000 cm³/ min (NTP)] with an air permeability of 137 to 168 m³/ min, which is the preferred minimum range of air permeability for a composite belt. The air leakage reading of the belt should preferably be at least about 70 marlats [about 3,300 cm³/ min (NTP)], and the belt air leakage reading should most preferably be at least about 100 marlates [about 4,500 cm³/ min (NTP)] under the same conditions (air permeability 137-168 m³/ Min).

The backside amount of texture is desirable, the upper limit is tekstuurimäärä, which allows the cross maximum amount of air to pass the papermaking belt 10. The backside 12 without the undesirable result that the suction pressure difference drops to less than that required to achieve the diversion of the papermaking belt of the paper web of the fibers 10 of the channels 36. It is believed that this may be as large as 250 marlats [about 8,400 cm³/ min (NTP)].

Figures 36A-36C and 37A-37C are enlarged photographs of papermaking belts made in accordance with two alternative versions of the method of the present invention. The photographs of the belt shown in Figs. 36A to 36C can be compared with the photographs of the previous belt with a smooth background shown in Figs. 35A and 35B.

A few points should be noted when looking at magnified photographs taken of these straps. Ensinil

123 it should also be apparent that, due to the magnification ratio used, the parts of the straps shown in the photographs are generally very small parts of the said slings. portions of the belts depicted in the photographs (and particularly mainittu5 of the belt backside texturing) is believed to represent a moderate size characteristics of the belt. However, this does not mean that there are no parts of the belt that better represent the characteristics of the whole belt as a whole than the parts of the belts shown in the photographs.

In addition, it should be noted that the strap parts shown in the photographs are most likely not exactly the same as the strap parts shown in other photographs taken from different angles, as it is difficult to view and photograph the very small features of such a product when magnified. In other words, the belt parts which form the paper-contacting side 11 and backside 12 may not actually be directly on top of the belt 10. Similarly, the belt cross-section of the photos may not represent the upper and cross-sections of the belt parts provided by the back side of the photo. The following is a look at these enlarged photos of the straps with this in mind.

Figures 35A and 35B are top plan photographs, approximately 25 times the actual size, of the paper contacting side 11a and the back side 12a, respectively, of the papermaking belt not disclosed herein. The belt shown in Figures 35A and 35B differs somewhat in size from the belts formed by the method of this invention because the belt shown in Figures 35A and 35B is a belt with a linear Idaho pattern 711. The belt shown in Figures 35A and 35B therefore has smaller channels 36 and larger. number of channels per area35 units.

124

The back side 12a of the belt 10A shown in Fig. 35B indicates one of the problems encountered in casting belts with smaller channels. Channels 36 tended to close on the backing surface 12a. 35B of the belt 10a shown in FIG backside 12a ideally should appear nearly identical to the Figure 35A by the paper-contacting side 11a. If the walls 44 of the channels 36 are inclined, the channels should appear smaller on the background surface and the area of ​​the background network should be larger. The deviation from the hypothetical ideal belt is also partly due to the minor imperfections in the belt, which proved to be greatly exaggerated in these photographs. When the back side 12 of the belt 10a shown in Fig. 1B is viewed under a microscope, the channel openings on the back side 12a of the belt 10a appear to be very similar to the channel openings on the paper-contacting side of the belt 10a. The belt 10a, however, this analysis reveals that the channels are covered with a very thin film of resinous material, which may at least partially account for the differences backside 10a of the belt 12a appearance.

Photographs of the belt 10 in Figures 36A-36C show a belt made in accordance with one alternative embodiment of the method of the present invention. the backside of the belt to these figures, the texture was formed by utilizing one of the layers of woven fabric texturized surface. The fabric of this single ply woven fabric is 18 x 20 (number of warp yarns per inch times the number of weft yarns per inch). This woven fabric was placed on top of a barrier film which was fed into the system in the same manner as the barrier film 76 shown in Figure 27. The fabric was then covered with another highly conformable barrier film to prevent contamination with resin. This second barrier film was fed in the same manner as the first barrier film

II

125 was introduced into the system. (However, the feed roll of the second barrier film was positioned so that this second barrier film was placed between the single layer woven fabric and the reinforcing structure.) The second barrier film was made of a material known as Ethyl Visqueen and is a 25 μm thick polyethylene film.

The photographs of the belt 10 shown in Figures 36A-36C are magnified about 25 times the actual size of the belt. Figure 36A is a photograph of the belt 10 with the paper-contacting side 11, which is taken to be about 35 degrees at the corner of the paper in contact with the side surface of an imaginary normal (ie. In the direction of z) of the. Fig. 36B is a photograph of the back side 12 of the belt 10 shown in Fig. 36A. Fig. 36C is a sectional view of the belt 10 shown in Figs. 36A and 36B.

Figure 36A shows that the paper side network 34a (which carries the paper web) is macroscopically monoplanar, patterned and continuous. As Figure 36A shows that the paper side network 34a is also microscopically monoplanar, patterned and continuous magnification of the photograph was taken. The paper side network surface 34a surrounds and defines the openings 36 of the plurality of channels 42, which channels the fibers in the embryonic web can be deflected and rearranged form of the improved paper web. The reinforcing structure 33 is visible in the holes or openings 41 found in the channels 36. The reinforcing structure 33 consists of a plurality of machine direction warp yarns 63 interwoven with a plurality of transverse warp yarns 54 so as to leave pores 39 therebetween. are generally a few times smaller than the channels 36. The reinforcing structure 33 reinforces the grid 32 without disturbing the flow of water and the passage of air through the channels 36.

Figures 36B and 36C show the backside 10 of the belt 12. Figures 36B and 36C show the backside teksturoin126 Nin, which is formed by the method according to the present invention, in one version. As Figure 36B shows, the back side 10 of the belt 36B shown in Figure 12 has a backside network 35a with a number of paper side network 34a and the continuity of the pattern features. The backside network 35a is unquestionably not one standard. Figure 36B shows that this abnormal level of one character is to some extent in that the yarns of the reinforcing structure 33 appear to cause the backside network 35a to bulge outward. These bulges form the passageways 37 that provide surface texture irregularities 38 in the backside network 35a.

Figure 36C shows that the bulges formed by the passageways 37 and irregularities 38 lisäk15 si a plurality of passageways 37 are positioned inwardly of the reinforcing structure of the machine-facing side of the plane defined by P_k2 pores 39 so that part of the projection of the surface of the passageways corresponds to part of the projection of the open surface of the reinforcing structure 33. Figure 36C also shows that a plurality of passageways 37 are positioned outward, toward the reinforcing structure of the plane defined by side P_k2. Figures 36B and 36C show that (at least) passageways 37 formed by the reinforcing bulges around the yarns 33 of the structure, have regular etäisyy25 della each other and positioned in the backside network 35a of the shape of Fig.

Photographs of Figures 37A-37C of the belt 10 show a belt made in accordance with another alternative embodiment of the method of the present invention. the backside of the belt to these figures, the texture was formed by utilizing a textured barrier film instead of a separate textured element or surface. The textured barrier film was made of a material known as Cracked Ice Embossed (CIE) 142

film and sold by Borden Chemical Company. Cracked Ice il

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Embossed (CIE) 142 film has a randomly distributed texture on the surface.

The angles at which the photographs shown in Figs. 37A to 37C are taken are the same as the angles at which the figures

36A-36C are taken. the belt 37A of Figure 10 paper side 11 of the characteristic features are also generally similar to that of Figure 36A by the paper side 10 of the belt 11. The backside 12 (and particularly the backside network 35a) are quite characteristics erilai10 set to Figures 36A - 36C by a belt.

Figures 37B and 37C show the method of the present invention prepared in another version of the belt 10 backside 12. The backside network 35a is neither monoplanar or continuous. Figure 37B of the belt 10 shown taus15 counterpart texture appears to fall into two general categories.

The backside texture of the first class seems to resemble a set of projections from the plane P_k2, defined by the machine side of the reinforcing structure. As shown in Fig. 37C, these protrusions appear in cross-section to form passageways 37 characterized by a single continuous curved wall. As also best seen in Figure 37C, these passageways 37 are surrounded or bordered by surface texture irregularities 38 that resemble ridges in cross section. All passages 37C shown in Fig. 37C are located outward from the plane P_k2, defined by the machine side of the reinforcing structure.

Another tekstuuriluokka found in sites from which there seems to have left whole pieces or portions of the backside network 35a. It is believed that this second type of texture may have arisen when portions of the liquid photosensitive resin coating have adhered to the Cracked Ice Embossed film and exited after the composite paper molding belt has separated from the Cracked Ice Embossed film after the kom128 positive belt has left the casting belt. Lines, which appears to have left 35 pieces of the backside network will flow passages 37, which connect to each other some of the channels along the belt 10 backside 12. It yhteenkytkeyty5, despite this, the paper side network 34a has remained relatively intact and provides discrete, isolated conduits 36, such as 37A shown in Fig. Both texture classes appear to occur relatively randomly.

Although specific embodiments of the present invention have been illustrated and described, it should be apparent to those skilled in the art that various other changes and modifications may be made without departing from the spirit and scope of the invention. The appended claims are therefore intended to cover all such changes and modifications as fall within the scope of the invention.