Apparatus for and methods of airlaying fibrous webs having descrete particles therein

The use of apparatus and apparatus for the manufacture of fiber optic fibers, for example, for the purpose of / or the use of an absorbent gelling material dispersed in the genome of the stone and part of the banana. Apparatus for use with a type of incubator and airfoil, including a perforated die (34) and a perforated forming element; that of the auxiliary means (36) for the ledge of the strap (54) of the air is provided with the fiber to the drum (34); en första huv (38); that the pressure drum (42) for the light drum (56) and the air flow of the fibrillary account, the color of the drum (56) 'the output of the drum (34) for the flow of the drum (34), the color of the drum (34) ). Powders are used for blocking the passage of the particle or the fiber to the fiber (54) for the purpose of reducing the use of the fiber and the fiber (54). Dessutom överspänner den första vakuumkammaren i läggtrumman den första huven (38) och en del av puderskikthuven (44) sä, att puderskiktet ej avskärs, skadas eller förstörs dÄ lägtrumman (34) roterar account den ställning, color den första puderskiktet.

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Apparatus and methods for supplying air to fibrous webs containing discrete particles

This invention relates to the supply of air to fibrous webs having discrete particles distributed over at least a portion of the web. More specifically, it relates to a device according to the preamble of claim 1 and a method according to the preamble of claim 17.

Porous gelling agents (AGMs) are polymeric materials that are capable of absorbing large amounts of fluids, such as body fluids and feces, and are also capable of retaining such absorbed fluids at moderate pressures. Due to the absorbent properties of absorbent gelling agents, such materials are highly preferred in absorbent articles such as disposable diapers, incontinence diapers and sanitary napkins. For example, Procter &amp; Gamble, EP-A-122 042, published 17. October 1984, discloses absorbent structures in which discrete particles of absorbent gelling agents (hydrogel particles) are placed in a path formed by hydrophilic fibers. In addition, U.S. Patent Application No. 734,426 / May 15, 1985 / to Paul T. Weisman, Dawn I. Houghton, and Dale A. Gellert discloses an absorbent article having a bilayer absorbent core, wherein the shaped core component comprises a substantially hydrophilic fibrous material and the inner core component comprises a substantially similar combination of hydrophilic fibrous material and discrete particles of an absorbent gel element.

However, there have been several difficulties in supplying air to absorbent core sheaths having multiple layers and / or layers containing a mixture of fibers and certain amounts of discrete material particles, such as absorbent gelling agents. The air supply device and methods require the removal of the gas or air carrying the fiber / particle2 from under the porous forming element of the air supply device. During this removal operation, small particles mixed with the fibers can generally pass through the openings in the air-forming material, resulting in the loss of expensive absorbent gelling agents through the air supply device, the finished absorbent product suction power decreases. In addition, the relatively large particles tend to prevent airflow through the porous forming element, as a result of which the uniformity of the basis weight of the product is affected by the fibrous web or absorbent core sheath and the machine has to stand while cleaning the porous forming element. Thus, it is preferred to provide an apparatus and methods for forming fibrous webs having discrete material particles, such as absorbent gelling agents, distributed over at least a portion of the web, the apparatus and methods minimizing clogging problems and material loss through the porous forming element. It is also preferred to provide apparatus and methods for forming air-containing multilayer fibrous webs.

The present invention relates to a solution in which a dusting layer of hydrophilic fibers is directed to a porous mud forming element before a mixture of hydrophilic fibers and discrete particles of absorbent gelling agent is applied thereon. This solution requires the use of two feed chutes and a hood placed on the circumference of the feed drum. It has been found that as the feed drum rotates from the dust bed feed chute to the first feed chute, the gutter shapes, fiber and air velocities, pressure difference at the dust bed edge and fiber / particle mixture exposure to the dust bed are wasted. Therefore, it is also desirable to provide an air supply device by means of which the dusting layer can be fed by means of air onto the porous forming element and the supply of the main layer using air onto the dusting layer without damaging or damaging it.

It is therefore an object of the present invention to provide an apparatus and method for air-fed fibrous webs in which the individual particles are distributed over at least a portion of the web.

Another object of the present invention is to provide an apparatus and method for supplying air to fibrous webs having a plurality of layers.

It is a further object of the present invention to provide an apparatus and methods that minimize equipment clogging problems and the loss of particles through the apparatus.

It is a further object of the present invention to provide a device in which the dusting layer is not damaged or broken when additional fibers or fiber / particle mixtures are fed onto the dusting layer by means of air.

In order to achieve the above objects, the device according to the invention is characterized in that the means for feeding the dust layer comprises a first sector and a second sector;

a dust layer suction device for drawing fiber-free air through said porous forming element, the dust layer suction device being located below the first sector of the dust layer supply device and the first suction device for drawing fiber-free air thus through the second porous forming element, the first suction device being located that damage or destruction of the dust layer formed on the porous forming element is prevented.

The method according to the invention, in turn, is characterized in that step (d) also comprises maintaining a pressure difference for drawing the dust stream conveying air flow through the porous forming element by means of a dust layer suction source located below the porous element in the first portion of the dust layer sector;

step (i) also comprises maintaining a pressure difference to draw the first layer fiber stream conveying air through the porous forming element by a first layer suction source located below the porous element in a sector of the first layer suction source also below the second portion of the dust layer sector downstream of the first pollination layer sector; and step (f) also comprises transferring the dusting layer under the effect of the pressure difference maintained by the suction source of the first layer in said second portion while the dusting layer is still located in the dusting layer sector of the porous forming element.

Although specific claims relating to the present invention have been made following this description, the present invention will be more readily understood by reading the following description and the accompanying drawings, in which Figure 1 is a partial side section of a preferred device according to the present invention; is a bottom view of a manifold device according to the present invention, Fig. 4 is a cross-section along the line 4-4 of Fig. 2, Fig. 5 is a cross-section along the line 5-5 of Fig. 2, Fig. 6 is a cross-section along the line 6-6 of Fig. 2, Fig. 7 is an enlarged cross-section of the transition zone of the manifold, Fig. 8 is a diagram of the present invention from the first feed chute,. Fig. 9 is an enlarged cross-sectional view of a first air supply device of the present invention; Fig. 10 is a sectional view of a preferred disposable absorbent article such as a diaper having a bilayer absorbent core sheath made with an apparatus and method of the present invention; and Fig. 11 is an enlarged cross-sectional view of

Although the invention is described in detail in the disclosure relating to the use of air-fed fibrous webs as absorbent core sheaths in absorbent articles, e.g., disposable sheaths, the present invention is in no way limited to this application. Namely, the present invention can be applied just as easily to air-fed fibrous webs, which are subsequently used in numerous products, including incontinence pads, sanitary napkins, wound dressings and the like.

Figure 10 shows a particularly preferred structure of a disposable sheath having an absorbent core sheath formed by the apparatus and method of the present invention. The disposable sheath 1000 has a surface layer 1002, a liquid impermeable base layer 1004 and an absorbent core sheath

1006 between the top layer 1002 and the bottom layer 1004. The preferred structure of such a disposable sheath is described in U.S. Patent 3,860,003/14. January 1975 / Kenneth B. Buell, which is incorporated herein by reference.

The absorbent core sheath 1006 preferably comprises two or more separate core components. The absorbent core sheath comprises an inner sheath component 1008 (first web component) and a shaped core sheath component 1010 (second web component). This preferred absorbent core sheath is described in more detail in U.S. Patent Application No. 734,426/15. May 1985 / Dale T. Weisman, Dawn I. Houghton and Paul E. Gellert, incorporated herein by reference.

The function of the shaped core jacket component 1010 is to rapidly collect and temporarily retain and disperse fluid secreted from the body into the jacket. Thus, the absorbent properties of the materials or fibers contained in the shaped core sheath component 1010 are very important. Therefore, the shaped core sheath component 1010 is an approximately hourglass-shaped plate of hydrophilic fibrous material. Although many fiber types are suitable for use in the shaped core sheath component 1010, the preferred fiber types are cellulosic fibers , specifically wood pulp fibers. Although the shaped core sheath component 1010 preferably does not contain absorbent gelling agent particles, the shaped core sheath component 1010 may alternatively contain small amounts of absorbent gelling agent particles to improve its liquid properties. Other materials, for example synthetic fibers, may be included in combination with the fibers in the core sheath component.

The inner core sheath component 1008 absorbs fluids excreted from the body from the shaped core sheath component 1010 and retains such fluids. As shown in Figures 10 and 11, the inner core jacket component 1008 consists essentially of a thin dusting layer 1012 of hydrophilic fibrous material overlaid with a primary layer 1014 in a uniform combination of hydrophilic fibrous material and certain amounts of non-absorbent particles 1016. The hydrophilic fibers of the inner core sheath component 1008 are preferably of the same type as those described in connection with the core sheath component 1010 formed above. There are several suitable absorbent gelling agents that can be used in the inner core sheath component, such as silica gels or organic materials, for example, network polymers. Particularly preferred absorbent gelling agents are hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, polyacrylates and isobutylene-maleic anhydride copolymers or mixtures thereof.

Although the dusting layer 1012 of the absorbent core sheath 1006 is a relatively thin layer of hydrophilic fibrous material, it should be noted that the term dusting layer used herein to mean a particular fibrous web layer or prefixed to denote certain elements that form or are used to form such a dusting layer but it comprises structures in which such a layer may vary in strength. For example, the dusting layer is preferably about 1.0 to about 1.5 ”(about 25 to about 38 mm) strong, more preferably about 1.25 (about 31.75 mm), although thicker and thinner layers are also possible.

Figure 1 shows a particularly preferred structure of an apparatus for forming air-containing fibrous webs having a plurality of components, such as the absorbent core 1006 of the disposable diaper 1000 shown in Figures 10 and 11. In the structure shown in Figure 1, the device 20 is shown comprising a pair of counter-rotating measuring feed rollers 22 which guide the dry material roll 24 into contact with a shredder 26 having a rotating tear element 28 partially enclosed in a housing 30, a distribution device such as a manifold 32 fibers, a first air supply device, for example a drum-type air supply. to form a first web component of the feeder 34, to direct a stream of first air supply fibers such as the first feed chute 36 and the dome 38 to the first air feeder and to feed the fibers to the first air feeder, to absorb the absorbent gel injector 40 or the device to absorb the absorbent gels; passing through the first feed chute 36 to direct a dust bed flow of fibers carried by a dust bed device such as the dust bed feed chute 42 and the dome 44 to the first air supply device and to feed the fibers to the first air supply device 46, a second air supply device, a second air supply device, e.g. for example, a second supply chute 48 and a dome 50 for directing a second stream of airborne fibers to the second air supply device and for feeding the fibers to the second air supply device, and a connecting device, e.g., a connecting roller device 52 for connecting the first and second track components. To simplify the description, a number of elements or devices that are readily available to those skilled in the art have been omitted from the drawings. Such elements include various components, bearings, transmission units, control devices and the like. The first stream 54 of air-transported fibers is further shown in Figure 1 as passing through a first feed chute 36. The dust layer flow 56 of the air-transported fibers is shown as moving through the dust bed supply chute 42. The second stream 58 of air-transported fibers is shown as moving through the second feed chute 48. The continuous flow of inner core jacket components 1008 (first track components) is shown as moving on the belt of the first discharge conveyor 62 and the continuous flow of shaped core jacket components 1010 (second track components) is shown as moving on the belt 64 of the second discharge conveyor 66.

A preferred construction of the tearing device 26 is shown in Figure 1 and comprises a rotating tearing element 28 partially housed in the housing 30. A tearing device of the same type is disclosed in U.S. Patent 3,863,296 / 4. February 1975 /

Kenneth B. Buell, which is incorporated herein by reference. As used herein, the term tearing device is not intended to limit the present invention to the device disclosed in the aforementioned patent, but includes, for example, hammer mills, fiberizers, collecting rollers, pre-winding rollers, or other devices that cut a roll or web of fibrous material into discrete fibers.

As used herein, a fibrous or dry material or sheet means any sheet of fibrous material that can be torn into discrete fibers. The fibrous material may be, for example, rayon, polyester, cotton or the like, with cellulose fibers being particularly preferred.

The tearing device 26 is preferably a rotating tearing element 28 having a plurality of rotors and a housing 30 having an approximately cylindrical hole 70. The shaft 72 is mounted at closed ends of the housing 30 so that one end of the shaft 72 is outside the housing 30 and allows the shaft to be connected to a power source. for example an electric motor (not shown). The motor drives the shaft 72 in the direction shown continuously. The rotors 68 are wedged into the shaft 72 in parallel, each comprising a plurality of teeth 74 extending outwardly so that their tips can act as impact elements. The term rotor, as used herein, means thin rotating plates. In the above arrangement, successive teeth 74 strike the end of the feed plate 24 as the rotors rotate. When the rotors 68 are wedged into place and compressed together, they form an axial, rotating and cylindrical tearing element 28 which rotates on a cylindrical shaft. This structure is therefore preferred because it allows a favorable internal distribution of the loads generated during operation of the tearing device 26.

The housing 30 is partially around the tear element 28 and defines a flow channel 78 for the fiber column between the tear element and the housing 30. The flow passage 78 is sized to form an opening of about 1/32 to about 1/4 (about 0.79 to about 6.35 mm) between the blade tips of the tearing element 28 and the housing 30 to guide the fiber column from the inner end of the housing to the manifold 32. The housing 30 has a cylindrical hole 70 partially around the tear element 28 and the inlet portion 80 with an opening to form an inlet opening having an inner end. (Although the housing 30 may alternatively consist of additional elements, they are not recommended in the present invention). The inlet 80 is arranged to receive the fiberboard 24 and guide it to the inner end which defines the support element of the board at which the edge of the fiberboard 24 is torn.

In the above arrangement, successive teeth 74 strike the end of the feed plate 24 as the rotors 68 rotate to separate the fibers of the fiberboard 24 into separate fibers. When the fibers of the fibreboard are separated into separate fibers, a fiber column is formed for the axial width of the housing 30. As used herein, the term fiber pillar refers to a fiber pattern or system positioned across the axial width of the housing. The rotation of the tearing element 28 imparts a certain specific velocity to the fibers over the axial width of the housing 30, after which a continuous column of fibers is directed around the flow channel 78 towards the manifold 32.

As shown in Figure 1, the manifold 32 is preferably connected to the housing 30 of the tearing device 26. The term is referred to as structures in which the manifold 32 is a separate element directly or indirectly connected to or within the housing 30 (i.e., as a separate structure integral therewith) or structures in which the manifold 32 forms the same element as the housing 30 so that the manifold 32 is a continuous and indivisible part of the housing 30 (i.e., a unitary structure). Although the manifold 32 may be a separate device from the tearing device 26 or the manifold 32 may be of the same construction as the housing 30 of the tearing device 26, such structures are not recommended. The manifold 32 is thus preferably a part connected to the housing 30 of the tearing device 26.

Figure 2 shows a particularly preferred structure of an apparatus (distributor or manifold 32) for generating a plurality of air-transported fiber streams by dividing a fiber column into a plurality of fiber streams and transferring each fiber stream separately into contact with the air. As shown in Figure 2, said device comprises a divider 200 having a plurality of openings made in it and on its surface. As also shown in Figure 2, the openings are marked as a first opening 202, a second opening 204, a third opening 206, and a dust layer opening 208. The device also includes a plurality of separate conduits, e.g., ducts, for directing high velocity air columns past openings 200. The ducts are marked in Figure 2 according to the opening to which each duct is connected, whereby a first duct 210, a second duct 212, a third duct 214 and a dust layer duct 216 are obtained.

The manifold 32 shown in Figure 2 is a preferred structure of the present invention. The manifold is shown in Figure 2 further comprising a base 218, four side walls 220, 222, 224 and 226, respectively, and a top wall 228 defining a divider 200. The base 218 preferably extends over the side walls 222 and 226 and defines flanges 230 having holes 232, so that the manifold 32 can be bolted or otherwise secured in the normal manner to the housing 30 of the tearing device 26. Figure 3 illustrates a preferred structure of a base 218 shown comprising outlets for each pipe passage. As shown in Fig. 3, the outlets are labeled as a first outlet 234, a second outlet 236, a third outlet 238, and a dust layer outlet 240.

The dividing section 200 forms a device for dividing the fiber column into a plurality of fiber streams. The divider 200 directs the fiber column to the openings, where the fiber column portions are divided into separate fiber streams. The term divider is used herein to describe a number of different structures that vary in shape, for example, channels, pipes, plates, or combinations of plates of material, a plurality of plates in combination, or a plurality of different elements in combination. The manifold 200 is shown in Figure 2 as a curved surface defined by the upper wall 228 of the manifold 32. However, alternative, preferred manifolds comprise a channel into which the openings are made, or, for example, if the manifold 32 is of unitary construction in the housing of the tearing device 26.

30 with, the manifold may comprise, in combination, a portion of the tear element 28, a surface of the housing 30 and the top wall 228 of the manifold 30, which then together define a flow passage 78 through which the fiber column can be guided.

Although the manifold 200 may vary in shape, the surface comprising the openings is preferably curved in profile. The curved profile provides a certain angular displacement and velocity components to the fibers to facilitate their separation and to pull them into separate tubular channels without mechanical edges or walls adhering to the fibers, so that clumping of the fibers is minimized. Although the present invention is assumed to use flat or straight dividers, they do not provide this angular displacement advantage, as will be described later. In addition, when the manifold 32 is connected to the housing 30, the curved divider corresponds in shape to the tear-off element 28. Although the curved profile of the divider is preferably circular, many different curved profiles are equally preferred, e.g., hyperbolic, parabolic, or ellipsoidal profiles.

The divider 200 can be located at any point where the fiber column is disassembled by the tear element 28. The manifold 200 of the manifold 32 can be located, for example, downstream of the tearing device 26.

However, this form of placement is not recommended because the fibrous statue tends to lose its momentum and easily changes in width into fibrous pads the farther from the tearing element 28 the divider 200 is placed. Thus, it has been found that in order to achieve the cleanest and most accurate splitting (splitting to obtain uniform fiber weights and minimize fiber clumping), the divider 200 should be located as close as possible to the tear element 28 so that the fiber column moves away from the tear element when split into fiber streams.

As shown in Figure 2, the manifold 200 has a plurality of openings. By means of the openings, the air columns which pass through the ducts come into contact with the part of the fiber column which runs along the distribution part 200, whereby parts of the fiber column can be split. Thus, said openings form a certain working opening for drawing the flow of fibers into the pipe channels. Although the openings may vary in shape, a rectangle with a countercurrent edge and a downstream edge is recommended for the shape of each opening. (These edges are shown and described in more detail in Figures 4, 5, and 6).

In order to split the fibers efficiently, at least two ports must be at least partially separated from each other laterally. As used herein, the term laterally spaced means that a portion of the aperture is moved to one side of at least a particular portion of the second aperture and away from its line so that a line perpendicular to its lateral dimension does not intersect both apertures. tSide dimension refers to the width of the divider). Thus, a partially laterally spaced aperture again means that a portion of the first aperture is located on the other side of the second aperture and away from its line. The openings may alternatively and preferably be completely axial. In addition, each opening may be either longitudinally aligned with or separate from the other opening on the downstream or upstream side. The term longitudinally apart is used herein to mean that a particular opening is located on the upstream or downstream side of another opening. (Longitudinal here means a measure corresponding to the length of the division). The preferred embodiment provides that each successive opening is laterally and longitudinally separated from each subsequent opening. This shape guarantees the most efficient splitting function of the fiber column.

As shown in Figure 2, the first opening 202 is preferably located close to the side wall 232 of the manifold 32, the outermost portion of the fiber column being then divided by the first opening 202. The second opening 204 is preferably longitudinally spaced downstream and laterally spaced apart from the first opening 202, thereby splitting the second width of the fiber column. The third opening 206 is preferably longitudinally aligned with the first opening 202, but laterally spaced apart from both the first and second openings so that the third fiber width is detached from the fiber column. The dust layer opening arranged at the same time as the fiber stream used to form the dust layer is longitudinally aligned with both the first and third openings 202 and 206, but laterally spaced apart and laterally aligned with a portion of the second opening 204, but longitudinally separate therefrom. Although the openings may be arranged in different patterns in the longitudinal and lateral directions, the structure shown in Figure 2 is preferred, in which a fibrous web comprising two core components is provided, one of these components comprising discrete particles of absorbent gel placed through one layer thereof.

The first and third openings 202 and 206 are preferably at the outer edges of the divider 200 relative to the second opening 204, thereby providing variations in the width of the dry web fed to the tearing device 26. Since the fiber streams forming the first and third openings 202 and 206 coincide in the first feed chute 36 downstream of the manifold 32, if there are greater variations in the width of the dry track 24, this variation does not cause a significant change in the first and third fiber stream into the same fiber stream. The first and third apertures 202 and 206 should therefore be of the same width and symmetrically positioned around the centerline of the manifold 32 or manifold 200.

Although the dust layer opening 208 is preferably separated from all openings both laterally and longitudinally so that the fiber column is more efficiently divided into four fiber streams, space and size requirements require that in the preferred construction of the manifold 32 with the first and third openings 202 and 206. The aperture 208 of the dust layer is laterally aligned with a particular portion of the second aperture 204 because the second aperture 204 is preferably much wider than the first and third apertures 202 and 206, thus minimizing the final basis weight of the second fiber stream. As shown in Figure 2, the dust layer opening 208 is preferably laterally spaced apart from the edge of the second opening 204 of the centerline of the manifold 32, so that the potential effect of removing the dust layer

The ducts form a device through which the high-velocity air column and also the currents of the fibers carried by the air are directed or pass. The pipe ducts may be separate elements, such as pipes, ducts or wires, attached to the manifold 200 at the openings, or a separate element formed by the placement of the plates as shown in Figures 4, 5 and 6. The conduits may be designed for flow rates that preferably exceed or equal to about 75 ACFM tear-off elements per 28 widths, preferably at speeds greater than or equal to about 6,000 feet per minute, but more preferably about 10,000 feet per minute. The ducts are thus recommended to be made about 1 strong and wide enough so that they are completely connected to the entire width of the opening to which the duct is in turn connected. Although the cross-sectional shape of the tubular ducts can be any, rectilinear curved ducts with a radius of curvature greater than about 6 are specifically recommended. , curved duct sizes are specifically recommended due to shape requirements and equipment arrangement.

The inlets of the ducts form a device for spraying or drawing the ambient air into the ducts at relatively high speeds. Although the shape of the inlets may be very different, the aerodynamic shape is believed to minimize the vortex state of the air when the air is drawn into the tube.

Figure 3 shows a preferred shape of the outlets at the bottom 218 of the manifold 32. The first and third outlets 234 and 238 preferably correspond to the width of the bottom so that the first inlet 210 connecting the fiber streams downstream can be conveniently attached to both outlets. The dust layer outlet 240 is slightly offset from the first and third outlets 234 and 238, making the dust bed feed chute easier to install. The second outlet 236 is different from all other outlets due to the shape of the second pipe channel and to facilitate the arrangement of the feed drums.

The percentage by weight of the total air felt per absorbent core sheath that makes up all of the particular core components will vary depending on the size of the absorbent article being made. Thus, a large sheath may require a higher percentage of the total weight of the air felt in the shaped core component than in a medium-sized sheath. Since the axial width of the openings determines the weight percent of the air felt of each core component, it is recommended that the axial width of each opening with the total axial width · of the divider 200 can be varied according to the weights of the air component of the core component. Therefore, the manifold 32 is preferably made of a group of plates that are bolted or otherwise attached to each other in a normal manner to create chambers of different sizes so that the width of each orifice and the width of each conduit can be varied to match the base weight required for the finished core component.

Figure 4 is a cross-sectional view taken along line 4-4 of Figure 2 of a preferred construction of the manifold 32. A cross-sectional view shows a manifold 200, a third opening 206, and a third tubular passage 214 having an inlet 237 and an outlet 238 in a third chamber or in the distribution area of ​​a manifold 32. (Although the present invention will be described with reference to a third chamber or division, it should be noted that the description applies equally well to the first chamber or division). The above-mentioned elements are preferably formed and delimited by three plates, which are a top plate 400, including a power plate 402 and a bottom plate 404.

The top plate defines a portion of the top wall 228 or manifold 200 of the present invention and also the top wall of the third tube passage 214, a portion of the inlet 237 and the upstream edge 406 of the third opening 206. The upper portion 400 defines a portion of the third opening 206 round profile. This shape is therefore preferred so that the third facing portion of the fiber column begins to detach from the tearing element 28 because it lacks the tension created by the conical countercurrent edge 406 and also because each fiber has a certain angular velocity component tangential to its angular path tending to deflect or release on the tear-off element 28.

The downstream plate 402 defines a portion of the divider 200 downstream of the third opening 206, a portion of the wall of the third tube passage 214 and a portion of the bottom 218 of the divider groove 32. In addition, the downstream plate 402 defines a downstream edge 408 of the third opening 206.^- the point at which a considerable amount of fibers moves away from the teeth of the tearing element and is directed into the tubular channel. As a result of this removal of fibers at the downstream edge, a lot of fibers accumulate at the downstream edge. The term downstream edge is used herein only to clarify the matter. Namely, this edge removes very little fiber, hardly any, from the teeth 74 of the tear element 28. Namely, most of the fibers are removed due to the effect of the pressure difference at the opening and the effect of the angular velocity and the momentum of the fibers when the fibers are pulled out of the tearing element. Thus, the accumulation of fibers at the downstream edge 408 is reduced.

The base plate 402 defines the wall of the third pipe channel 214 and also a part of the base 218 and the side wall 224 of the manifold 32.

Figure 5 is a cross-sectional view of a preferred manifold structure taken along line 5-5 of Figure 2. A cross-sectional view shows a manifold 200. A second opening 204 and a second tubular passage 212 having an inlet 235 and an outlet 236 in a second chamber or manifold 32 of the manifold 32. (No fiber layer of dust layer is formed in this part of the second chamber). The aforementioned elements are preferably formed and delimited by three plates, including a top plate 500, a downstream plate 502, and a bottom plate 504. These plates are arranged in the same manner and delimit the same portions of the manifold as the plates shown in Fig. 4 except that the second opening 204 and the second Pipe Ducts 212 are arranged downstream along the manifold 200 in which the first and third openings 202 and 206 are located. The countercurrent edge 506 and the downstream edge 508 of the second opening are also shown in Figure 5.

Figure 6 shows a cross-section of the preferred structure of the manifold 32 along line 6-6 of Figure 2. A cross-sectional view shows a manifold 200, a dust layer opening 208, a second opening 204, a dust layer tube passage 216 having an inlet 239 and an outlet 240, and a second pipe passage 212 having an inlet 235 and an outlet 236 in a manifold dusting chamber. Although the dusting layer chamber can be constructed in many different ways, also as shown in Fig. 4, in which case no second opening and channel is formed in the dusting layer chamber, such structures are not recommended. The above elements are preferably formed and delimited by six plates, including a top plate 600, a spacer plate 602, a downstream plate 604, a side plate 606, a base plate 608, and a wedge plate 610.

The manifold 200 is formed from the upper surfaces of the top plate 600, the spacer plate 602, and the downstream plate 604. The spacer 602 acts as a separator and defines the openings. The dust layer opening 208 is defined by a top plate 600 and a spacer 602, the top plate 600 defines a countercurrent edge 612 of the dust layer opening 208, and a spacer 602 defines a downstream edge 614 of the dust layer opening 208. The second opening 204 is defined by a baffle 602 and a downstream plate 604, the baffle 602 defines a countercurrent edge 508, and the downstream plate 604 defines a downstream edge 510 of the second opening 204. The dust layer 602, with a downstream plate 604 and a base plate 608. It should be noted that the second pipe channel 212 is closed by the wedge plate 610. The wedge plate 610 is a plate having conical ends and a square hole through the plate, thereby blocking the flow of air through the portion of the second duct 212 that communicates with the dust layer duct 216 but allows air to flow through the dust layer duct 216.

Specifically, for example, the manifold 32 has 27 groups of plates along its entire width, with each plate having a width of about 5/8 (about 15.8 mm). Thus, the cumulative width of the manifold 32 is about 17 (about 432 mm). The first and third chambers are formed of about 4 to about 8 plates, each of which is structured such that the widths of the first and third openings 202 and 206 are about 2.5 to about 5.0 (about 63.5 to about 127 mm). The second chamber is formed of about 13 to about 20 plates so that the width of the second opening 204 is about 8.12 to about 12.5 (about 206 to about 317.5 mm). Of these 13-20 sheets, about 2 to about 4 sheets are made to provide a dust bed chamber, wherein the width of the dust bed opening 208 is from about 1.25 to about 2.5 (about 31.75 to about 63.5). The dust layer chamber is separated from the first chamber by at least two plates or about 1.25 (about 31.75).

The manifold 32 is preferably operated so that each air column drawn through the ducts has a velocity of about 6,000 to about 15,000 feet per minute (about 1.83 to about 4.57 km per minute), more preferably about 10,000 feet per minute (3.05 km per minute), and a flow rate of about 40 to about 100 ACFM per inch, however, preferably about 75 ACFM per inch.

Figure 7 shows an enlarged cross-section of a preferred structure of a manifold 32 at an opening of the present invention. The tearing element 28 is shown to rotate counterclockwise. The divider 200 5 having the opening 700 is shown to be a curved surface formed by the top plate 702 and the downstream plate 704. The pipe channel 706 is formed from the surfaces of the top plate 702, the downstream plate 704 and the bottom plate 708, and the inlet opening of the pipe channel 706 is indicated by reference numeral 710 and the outlet opening by reference numeral 712. Also, as shown in Figure 7, the tear element 28, the manifold 200, and the housing (not shown) define a narrow flow passage 714 through which the fiber column 716 is directed. The countercurrent edge 718 of the opening 700 (at the edge opening 700 of the top plate 702) is shown to taper away from the tear element 28 in Figure 7. (As mentioned earlier, this shape is recommended so that the fibers can begin to detach from the tear element). The downstream edge 720 of the opening 700 (at the opening 700 of the edge of the downstream plate 704) is shown to include an inner angle A delimited by the tangents of the plate surfaces. The tangent detachment point marked with an X in the figure

7, is the bounded point where the tangential component of the angular velocity of the fiber is such that the fiber tends to release its angular path away from the tear element 28. Although the tangent release point may be located either upstream of or close to the opening 700, it is recommended that the tangent release point be located somewhat upstream of the opening 700, thereby obtaining the maximum possible peeling power and minimizing fiber clumping.

It has been found that the geometry of the parts can play an important role in minimizing fiber agglomeration.

The angle muodost formed between the countercurrent edge 718 and the downstream edge 720 defines the actual size of the opening 700. The actual size of the aperture should preferably not be greater than about 60 °, preferably about 15 ° to about 45 °, and most preferably about 30 °. Angle C bounded by the angle between the tangent detachment point X and the downstream edge 720.

determines the actual size of the aperture 700. The effective aperture preferably does not exceed 75 °, but is preferably about 30 ° to about 60 °, and most preferably about 40 ° to about 45 °. Thus, the tangent release point should not be about 15 ° more upstream of the opening 700. It has also been found that the inner angle A is preferably about 15 ° to about 60 ° ', most preferably about 45 °. It should also be noted that the angle between the openings from the center to the center should preferably not exceed about 90 °, but should preferably be about 30 ° to about 60 ° and most preferably about 30 ° to about 60 ° and most preferably about 45 ° so as to obtain sufficient distance between the openings to minimize the interaction between them.

The operation of the device according to the present invention will now be described with reference to Fig. 7. The fiber column 716 is directed around the flow channel 714 along the manifold 200 of the manifold 32 by the pumping operation of the tear element 28. The fiber column 716 extends along the curved surface of the divider so that the angular movement and thus the angular velocity and momentum are applied to each fiber in the column. At the same time, the high velocity air column is directed through the duct 706 and past the opening 700. This air column can be provided by any conventional device (not shown), for example a fan arranged to spray air through the inlet 710 of the duct 706, or a vacuum device located downstream of the outlet 712, preferably under a porous forming element in a drum-type air through the inlet 710 of the pipe duct 706.

While not wishing to be bound by theory by maintaining a high air velocity statue (at least 6,000 feet per minute and preferably about 10,000 feet per minute) flowing through the ducts, it is believed that a certain pressure difference or small forward zone is formed between the flow duct pressure and the duct pressure. to, under or under. Due to the pressure difference caused by the movement of the air column and the angular velocity and mass-based momentum of the fibers, the fibers tend to detach from the tear element and orient in a path formed by the conical edge of the countercurrent edge as the fibers move to the first tube channel. Thus, the mechanical function of the downstream edge does not need to split the fibers, but splits under the influence of air and fiber momentum, thus minimizing caking due to the absence of mechanical edges or walls.

The fiber stream sucked into the pipe duct then enters the air column and the resulting stream with air-transported fibers is directed downstream and out of the outlet into a corresponding feed chute. This process is repeated in each orifice to provide numerous, discrete air streams carried by the air.

The feed chutes form a device for directing air-transported fibers from the manifold 32 to a single air supply device and for feeding the fibers to the air supply device.

The supply chutes preferably also slow down the air flows carried by the air and direct the fiber flows from the outlets so that they correspond to the width and location of the air supply device.

The feed chutes may comprise any part known in the art with which the above functions can be performed. However, the feed chutes are preferably ducts designed to slow down fiber flows and minimize clumping of fibers as they reorient from the manifold to the air supply device. The feed chute should be designed to provide a reduction in air velocity while keeping the shrinkage and expansion angles of the chute to a minimum. The gutters cause about a 2/3 reduction in air velocity, but preferably they reduce air velocities by a factor of 3 so that the fibers do not collide with the feed drum at high speed. Thus, the walls of the feed chutes should have different curvature and cone shapes, which provide a gradually increasing cross-sectional area to reduce the speed of the fiber flows.

The feed chutes are preferably rectangular in cross-sectional area.

As shown in Figure 7, the first feed chute 36 is preferably in the Y-shape, with the first and third fiber streams merging into the main fiber stream. The first feed chute 36 is preferably designed to minimize the vortex space due to the merging of the two fiber webs. Thus, the chute preferably has a fifth class polynomial curve profile or other profiles with zero first and second derivatives to combine the fiber streams into a single stream.

As shown in Figure 1, the device 20, and in particular the first supply shaft 36, is preferably provided with a device which forms separate absorbent gelling particles. The absorbent gelling injector 40 mixes the individual absorbent gelling particles into the main stream of airborne fibers prior to supplying the first air supply device. An exemplary construction of a spray device is disclosed in U.S. Patent 4,551,191 to Ronald W. Kock and John A. Esposito. November 1985, which is incorporated herein by reference. The spray device preferably comprises a funnel (not shown) in which a certain amount of absorbent gelling agent is stored, a supply device (not shown) which measures how much absorbent gelling agent enters through the inlet duct 172 to the vacuum cleaner 174, which enters an air-absorbent gelling agent, without transporting absorbent gelling particles to the fiber streams. The absorbent gelling agent is transferred and then mixed with the fiber streams before being fed to the feed drum. Other suitable spray devices known in the art may also be used in the invention. In addition, any other feed chute can be equipped with an absorbent gelling feeder, if necessary.

A combining device is a device that 'connects the components of a fiber path. The term joining is used herein to indicate that the tracks are connected to each other directly or indirectly to form an air-containing fibrous track. Although many such splicing devices are already known in the art, the preferred splicing device comprises a pair of two splicing rollers on which the assembled inner core components are guided in a continuous stream to be placed adjacent to the shaped core components.

According to the present invention, any other connecting devices having structures in which the inner core components are blown out of the first air supply device directly to the shaped core components may also be used.

Figure 1 shows a first and a second air supply device for forming fiber paths, and preferably comprise a drum-type apparatus. Although the air supply device according to the present invention may alternatively have many different constructions, for example a movable, porous screen, a drum type air supply device is specifically preferred. A typical drum air supply device suitable for the present invention is disclosed in U.S. Patent 4,388,056 / FB to Lee and O. Jobes, Jr / 14. June 1983 and U.S. Patent Application No. 576,098/1. February 1984 /

BR Feist, JE Carstens, and DA Peterson, incorporated herein by reference. Although the present invention can be applied using a drum-type air supply device that forms either a continuous web or separate products, the following description relates to a drum-type air supply device for making separate fiber paths.

The first drum-type air supply device 34 is shown in Fig. 1 and comprises a first supply drum 100 having a porous forming element (not shown) around the drum circumference, a first connecting roller 102, a first blowing device or nozzle 104, a first discharge conveyor 62 positioned around support rollers 106, and a first transfer box 108 located below the upper track of the discharge conveyor 62. The second drum type air supply device 46 preferably comprises a second supply drum 110 having a porous forming element (not shown), a second connecting roller 112, a second blowing device or nozzle 114, a second discharge conveyor 66 disposed around the support housings and a second transfer suction box 118 located above the second discharge conveyor 66 under. Devices not shown in Figure 1 comprise house actuators, differential pressure devices with a vacuum supply duct, a fan and a fan actuator for sucking non-fibrous air through both porous forming elements and for removing air from the drum through the duct.

Thus, the device 20 converts a continuous length or roll of dry material into successive fibrous webs used as absorbent cores in disposable diapers, sanitary napkins, and the like. As shown in Figure 1, the roll of dry material 24 is opened into a web which is fed to a tearing device 26. The web is fed radially to the tearing device 26 by means of two counter-rotating measuring feed rollers 22. The inlet 80 of the housing 30 of the tearing device 26 receives the fiber web and guides it to the inner end of the housing 30, where the edge of the fiber web is torn into a fiber column that is the axial width of the housing 30. The fiber web is guided around the flow passage 78 by the pumping operation of the tearing elements 28 to the manifold 32. The fiber column is divided into a plurality of fiber streams associated with the air manifold 32, with air-flowing fiber streams directed out of the manifold 32 to the feed chutes.

The fiber layer 56 of the dusting layer is directed through the feed chute 42 of the dusting layer to the first feed drum 100, by means of which the fibers are fed onto its porous forming element. The first fiber stream 54 and the third fiber stream (not shown) are preferably connected to each other and directed through a first feed chute 36, where the combined fiber stream mixes with separate absorbent gelling particles which are injected into the first feed chute 36 by an absorbent gel gun. The mixture thus formed is fed to a first feed drum wood 100, after which a mixture comprising fibers and an absorbent gelling agent is fed to the porous forming element on top of the dusting layer downstream of the place where the dusting layer is formed. The fiber-free transport air is drawn through the porous forming element by means of a vacuum behind the porous forming element. The fibrous web component thus formed is then transferred to the first discharge conveyor 62 by the blow-off nozzle 104 and by means of a transfer suction box located below the conveyor belt. The second web component is preferably formed in the same manner as the first web component by passing the second fiber web 58 through the second feed chute 48, feeding and collecting the second fiber stream 58 to the porous forming element of the second feed drum 100 and transferring the second web component thus formed to the second discharge conveyor 66.

Prior to assembling the track components, they can be finished by various operations, such as calendering, coating, or reinforcement in a manner known in the art. As shown in Figure 1, the first web component is wrapped in a particular fabric by means of a folding plate, after which a continuous stream consisting of the first coated core sheath components is directed to the connecting rolls. The track components are then connected to each other by directing a continuous stream of coated first track components onto the connecting device or rollers 52, after which they are contacted with the second track component. If desired, other additional operations may then be performed on the downstream side of the forming device or rolls 52 to form the finished absorbent disposable product, for example a disposable diaper.

Figure 9 shows an enlarged section of a preferred construction of a first drum type air supply device 34 according to the present invention. As shown in Figure 9, the apparatus for forming fibrous webs having discrete particles or multiple layers fed therein preferably comprises a feed drum 100 having a porous forming element consisting of a plurality of forming recesses 120 spaced around the circumference of the drum 100. The number of recesses 120 may vary depending on the size of the drum 100 or the size of the tracks to be formed. In the structure shown, the drum 100 has six recesses. A plurality of ribs 122 are disposed within the drum 100 and define a dust layer of a vacuum chamber 124, a first vacuum chamber 126, a storage vacuum chamber 128, and a blow chamber 130 having a blow device or nozzle 104. Each vacuum chamber is connected to a suitable vacuum source (not shown). Preferably, the apparatus also comprises a dust layer feed device, e.g. direction around a certain portion of the first vacuum chamber 126. Figure 9 also shows a first feed device, such as a first feed chute 36 and a hood 38, for directing a first flow of air through the first sector 136 of the feed drum 100, the first dome 38 then comprising sufficient circumferential length to surround the rest of the first vacuum chamber 126. The apparatus further comprises a spool roller 102, a sealing roller 137, and an discharge conveyor 62 for moving a continuous stream of discrete fiber paths 138 or core sheath components.

A crucial feature of the present invention is that the first vacuum chamber is located not only below the entire first dome 38, but also below the second sector 136 of the dust layer dome 44, so that approximately similar pressures are generated at the intersection point 140 of the domes. Since each dome preferably comprises one complete recess 120 (measured from the edge of the first recess to the corresponding edge of the second recess) or about 60 ° for a drum having six recesses, the circumferential length of the first vacuum chamber 126 must be about 75 ° larger than the second chamber for the structure shown in Figure 9. Although the circumferential length of the portion of the first vacuum chamber 126 below the dust layer dome 44 (i.e., the circumferential length of the second sector 136 of the dust layer dome 44) has not been considered particularly critical, there must be sufficient space to provide a minimum transition zone between the dust layer dome 44 and the first dome 38.

This minimum circumferential length decreases as the number of recesses 120 increases and increases as the number of recesses 120 decreases.

Another crucial feature is that there must be a small gap 142 between the feed drum 100 and the intersection point 140 of the outer surface domes to equalize the pressure in the portions of each dome near the intersection point. If there is no gap, the pressures of both hoods are different, so that as the drum moves the edge of the dusting layer to the first dome 38, this pressure difference causes the dusting layer to detach from the screen. If the gap is too large, the two feed chutes practically merge into one and do not produce a separate dusting layer. Thus, a gap 142 of up to about i, but preferably 1/8 a gap, is preferred so that the pressure can equalize in the portion of each dome at the intersection 140.

Another important structural feature is that each dome should have a relatively wide, circular constriction near the intersection point 140 so that the fibers directed to the feed drum in this area do not collide with the dusting layer at an acute angle. When the fibers impinge on the dust layer at an acute angle, they have a velocity component parallel to the surface of the drum, whereby the fibers tend to cause the fibers forming the dust layer to rise or break. The critical burst rate is estimated to be about 4,000 feet per minute; the gutter geometry is designed based on this limiting factor. It is therefore desirable for the fibers to collide with the fibers of the dusting layer at an angle as close as possible to the perpendicular, because · there is then no shear component. Thus, each dome should have a sufficiently wide, circular constriction so that the fibers do not collide with the dusting layer at an acute angle or exceed a critical shear rate. As shown in Fig. 9, each dome has a radius of curvature of approximately 3 at the point of intersection.

The device works as follows. The dusted layer stream formed by the fibers is directed toward the circumferential length of the feed drum 100 or the dusting layer sector 132 through the dusting layer dome 44 of the dusting layer feed chute 42. The circumferential length preferably corresponds to the circumferential length of one recess 120, i.e. about 60 ° if six recesses 120 are used. The fibers are fed to the porous forming element of one recess 120 of the drum 100 and the transport air is sucked through the porous forming element by means of a vacuum in the vacuum chamber 124 of the dusting layer and also by a vacuum in the first vacuum chamber 126. The dusting layer is thus formed as the fibers accumulate on the porous forming element.

As the drum rotates, the dusting layer moves from the area of ​​influence of the dusting dome 44 to the area of ​​influence of the first dome 38, where the first air flow carried by the air is directed substantially radially towards the circumference of the drum. However, it should be noted that the dusting layer has already been transferred to the area of ​​influence of the first vacuum chamber 126 before it passes between the domes, so that the pressure difference and the speed of the first stream do not tend to cut off the dusting layer. The fibers of the first fiber stream are thus fed onto the dusting layer and the transport air is sucked in through the porous forming element by means of a vacuum first in the vacuum chamber 126. The first layer is formed when a mixture of fibers and AGM is fed onto the dusting layer. Since the dusting layer remains essentially intact, the discrete particles of the absorbent gelling agent do not tend to pass through the porous forming element and do not support it, because the fibrous layer already covers the voids of the porous forming element.

The finished fiber web then goes under the connecting roll where the web is leveled. The fiber web 138 or the inner core component is then transferred to the discharge conveyor 62 by the combined action of the blow nozzle 104 and the vacuum below the conveyor belt. The fiber web 138 is then conveyed downstream for finishing a disposable, absorbent article, such as a disposable diaper, for subsequent treatments.

Although certain structures of the present invention have been shown and described above, those skilled in the art will appreciate that various changes may be made therein and the structures may be modified without departing from the spirit and scope of the invention. All such variations and intended uses are intended to be included in the appended claims.