Process for making an embossed web

Procedure to manufacture a stamped band.

Field of the Invention

The invention relates to a process for manufacturing a patterned web comprising a plurality of differentiated extended elements.

Background of the invention

Band materials, such as thermoplastic films, have a variety of uses, including absorbent article component materials (such as, for example, top sheets and backing sheets), packaging (such as wrapping as a bag, shrink film, and plastic bags), garbage bags, food wrap, dental floss, wipes, electronic components, and the like. For many of these uses of web materials, it can be advantageous for the web material to have a raised surface that can provide the surface of the web material with a desirable touch, visual impression, and / or audible impression.

Polymeric bands that have a silky soft touch impression can be manufactured by a vacuum forming process or a hydroconformation process. With a typical vacuum forming process, a precursor band is heated and placed on a forming structure. Next, a vacuum forces the conformation of the precursor band according to the relief of the forming structure. The resulting polymeric web has a texture that can provide a silky smooth tactile impression, depending on the texture of the forming structure and the degree of conformation. Although a vacuum forming process can be useful for manufacturing a soft and silky polymeric web, a vacuum forming process is typically limited with respect to the amount of pressure that can be exerted on a precursor web. Therefore, it is usually required to heat a precursor film to significantly soften or melt the precursor film before placing it on the forming structure in order to vacuum form the precursor film to obtain the forming structure. A vacuum forming process is, therefore, an inefficient process in terms of how quickly the process can be performed, due to the heating stage and the limited pressures generated by the process.

In a typical hydroconformation process, a precursor band is placed on a forming structure and high pressure and high temperature water jets force the formation of the precursor band according to the relief of the forming structure. The resulting polymeric web may have a texture that can provide a silky soft touch impression, depending on the texture of the forming structure. A hydroconformation process, although capable of producing soft and silky polymeric bands, is typically an expensive and inefficient process that involves the use of high pressure and high temperature water jets and subsequent drying stages, including drying stages. .

Stamping is a process that typically involves the action of mechanically working a substrate to make the substrate conform under pressure according to the depths and contours of an embossed design

or shaped in some other way on a stamping roller. It is widely used in the production of consumer goods. Manufacturers use the stamping process to convey a textured or embossed design to products made of fabrics, paper, synthetic materials, plastic materials, metals, and wood.

Stamping processes have been used to provide texture to polymeric films. However, such stamping processes typically require extruding a molten resin onto a forming structure or heating a precursor band before placing it on a forming structure and then stamping to produce a stamped band. The stamped band is then cooled, typically by cooling the stamping rollers or plates used to stamp the heated precursor band or molten resin. The cooling stage is often performed to adjust the texture of the patterned web. However, these heating and cooling stages add to the process an undesirable cost and inefficiency, as well as complexity. In addition, such stamping processes typically involve relatively long residence times, which can result in slow and inefficient processes.

Typically, it is also difficult to transmit a texture on a relatively small scale to the precursor bands using conventional printing processes. In addition, typical stamping processes tend to produce stamped bands that have a relatively uniform thickness along the band.

For example, US Pat. No. 5,972,280 describes a stamping process that uses a hot etched surface of a stamping roller and static pressure applied inside a chamber to heat a web and deform it along the surface of the stamped roller. . This process uses elevated temperatures that are typically higher than the band smoothing temperature, and relatively low pressures of about 0.007 MPa to about 0.7 MPa. As a result, the stamped design is formed as indentations arranged on a single surface of the band, without affecting the opposite surface of the band.

Despite existing knowledge in the art, it is still desired to develop a more efficient process for manufacturing patterned bands with a desirable touch, visual impression, and / or audible impression, especially patterned bands that have narrowing in desirable areas of the patterned band. In certain aspects, a desired process is effective with respect to the energy and sources required by the process. In certain aspects, a desired process can be carried out at high speeds. In certain aspects, a desired process can be carried out at low temperatures, such as at room temperature.

Summary of the invention

In one embodiment, a process for manufacturing a patterned web includes disposing a precursor web between a static pressure gas plenum and a forming structure having a plurality of distinct protruding elements. The method also includes applying pressure from the gas plenum at static pressure against the precursor band located in front of the forming structure, creating at least one differential pressure across the entire precursor band sufficient to form the precursor band according to the distinct protruding elements of the forming structure in order to form the patterned band comprising a plurality of differentiated extended elements having open proximal ends.

Additional features of the invention may be apparent to those skilled in the art from reading the following detailed description, together with the drawings, examples, and appended claims.

Brief description of the drawings

Figure 1 is a perspective view of a part of a forming structure according to an embodiment of the description;

Figure 2 is an enlarged perspective view of a part of the forming structure shown in Fig. 1;

Figure 3 is a top view of a forming structure according to an embodiment of the description;

Figure 4 is a side view of protruding elements of a forming structure according to an embodiment of the description;

Figure 5 is a photomicrograph showing a side view of a forming structure according to an embodiment of the description;

Figure 6 is a perspective view of a part of a patterned web formed by a process according to an embodiment of the description;

Figure 7 is a sectional view of a part of a patterned web formed by a process according to an embodiment of the description;

Figure 8 is a perspective view of a part of a patterned web having differentiated extended elements with open distal ends formed by a process according to an embodiment of the description;

Figure 9 is a schematic representation of a process according to an embodiment of the description, representing a static pressure gas plenum;

Figure 10A is a photomicrograph in bottom view of a patterned web formed by a process according to an embodiment of the description; and

Figure 10B is a photomicrograph in bottom view of a patterned web formed by a process according to an embodiment of the description.

Although the specification concludes with claims that specifically indicate and specifically claim the object that is considered to be the present invention, it is believed that the invention will be more fully understood from the following description, in combination with the drawings to be accompany. Some of the figures may have been simplified by the omission of selected elements in order to show more clearly other elements. Such omissions of elements in some figures are not necessarily indicative of the presence or absence of specific elements in any of the illustrative embodiments, unless otherwise indicated in the corresponding written description. None of the drawings are necessarily to scale.

Detailed description of the invention

This process describes a process for forming a patterned band that manages to overcome one or more of the deficiencies of the state of the art. Specifically, the process realizations now make a more efficient process of stamping the bands possible. For example, process embodiments now allow the ability to transmit relief on a relatively small scale to the bands. In addition, process embodiments can now enable the ability to avoid the expensive heating and cooling stages required in the state of the art. In addition, the embodiments of the process do not require the high residence times required in the state of the art processes. Additionally, compared to the static pressure processes of the state of the art, process embodiments may allow the formation of three-dimensional differentiated extended elements having open proximal ends and open or closed distal ends. In certain embodiments, the processes can be used to form macroscale structures to use, for example, as packaging materials such as, for example, bubble wrap.

The process generally includes arranging a precursor band between a static pressure plenum and a forming structure. The shaping structure includes a plurality of distinct protruding elements. The process also includes applying a pressure from a static pressure plenum against the precursor band and the forming structure that is sufficient to form the precursor band according to the differentiated protuberant elements of the forming structure to form the patterned band comprising a plurality of extended differential elements that have open proximal ends. These aspects of the process are described in detail below.

Shaping structure

A forming structure useful in the process of the present invention comprises a plurality of differentiated protruding elements and intermediate zones that completely surround the differentiated protruding elements. The distinct protruding elements of the forming structure of the present invention are on a reduced scale compared to the designs used in the dies in the stamping processes. The distinct protruding elements of the forming structure also have relatively high dimensional relationships. This combination of properties may allow the process of the invention to produce stamped bands comprising extended elements with relatively high dimensional ratios with narrow distal ends, even without heating the precursor band and even at high speeds.

A shaping structure of the present invention is used, such as the shaping structure 8 referred to with respect to Fig. 1, to manufacture a patterned web in the process of the present invention. Occasionally, reference will be made to the forming structure as a forming mesh. Fig. 1 shows a part of a forming structure 8 of the present invention in partial perspective view. The protruding differentiated elements 10 of Fig. 1 they extend from a first surface 12 of the forming structure and generally have column-like, pillar-like shapes.

Fig. 2 is an enlarged partial perspective view of the forming structure 8 shown in Fig. 1, and is comparable to the similar view of the embossed web 18 of Fig. 7. Differentiated protuberant elements 10 can be manufactured by methods described hereinbelow, so that they extend from a first surface 12 to a distal end 14. As shown in Fig. 2, differentiated protuberant elements 10 may have a height ("hp") measured from a minimum amplitude measured from the first surface 12 between adjacent projections to the distal end 14. As such, the first surface 12 constitutes a completely surrounding intermediate area the differentiated protuberant elements 10. The height of the protruding element hp may be at least about 30 micrometers, at least about 50 micrometers, at least about 75 micrometers, at least about 100 micrometers, at least about 150 micrometers, at least about 250 micrometers, or at least approximately 380 micrometers The protuberant elements 10 have a diameter ("dp") which, for a generally cylindrical structure, is the external diameter. For non-uniform cross sections, and / or non-cylindrical structures of the protruding elements 10, the diameter dp is measured as the average cross-sectional dimension of the protruding elements at ½ of the height hp of the protruding elements 10, as shown in Fig. 2. The protuberant elements may have a dp diameter that can be from about 10 micrometers to about 5000 micrometers. Other suitable diameters include, for example, from about 50 micrometers to about 500 micrometers, from about 65 micrometers to about 300 micrometers, from about 75 micrometers to about 200 micrometers, from about 100 micrometers to about 25,000 micrometers, from about 500 micrometers to about 5000 micrometers, or about 800 micrometers to about 2500 micrometers. In certain embodiments, the protruding elements may have diameters that give rise to extended elements differentiated to macroscale. For example, protuberant elements may have diameters of up to about 2.5 centimeters, up to about 2 centimeters, up to about 1.5 centimeters, up to about 1 cm, up to about 0.5 centimeters, or up to about 0.1 centimeters. In one embodiment, the protruding elements of the forming structure will have a diameter of less than about 500 micrometers, or less than about 300 micrometers.

For each protuberant element 10, a dimensional relationship for the protuberant element, defined as hp / dp, can be determined. The protuberant elements 10 may have a hp / dp dimensional ratio of at least about 0.5, at least about 0.75, at least about 1, at least about 1.5, at least about 2, at least about 2 , 5, or at least about 3 or higher. The protuberant elements 10 may have a center-to-center separation Cp between two adjacent protruding elements 10 of approximately 100 micrometers to approximately 1020 micrometers, approximately 100 micrometers to approximately 640 micrometers, approximately 150 micrometers to approximately 500 micrometers, or approximately 180 micrometers to about 430 micrometers.

In general, it is believed that the actual distance between two adjacent protruding elements 10 (ie, an "edge-to-edge" dimension) should be greater than twice the thickness t of the precursor band to ensure adequate deformation of the precursor band between adjacent protruding elements 10. Differentiated protuberant elements 10 will typically have an edge-to-edge separation of about 30 micrometers to about 800 micrometers, about 30 micrometers to about 650 micrometers, about 50 micrometers to about 500 micrometers, or about 60 to about 300 micrometers

In general, the forming structure of the present invention, for a given part of the forming structure, will comprise at least about 95 protuberant elements differentiated by square centimeter, at least approximately 240 protuberant elements differentiated by square centimeter, from approximately 350 to approximately 10,000 protruding elements differentiated per square centimeter, from about 500 to about 5000 protruding elements differentiated by square centimeter, or from about 700 to about 3000 protruding elements differentiated by square centimeter.

In certain embodiments, certain determined parts of the forming structure may comprise area densities of differentiated protruding elements as described in the preceding paragraph, and other parts of the forming structure may not comprise absolutely any protruding element. In other embodiments, the distinct protruding elements of the forming structure may be located in different horizontal planes of the forming structure.

In general, because the actual height hp of each individual protuberant element 10 may vary, an average height ("hpavg") of a plurality of protuberant elements 10 can be determined by determining an average minimum amplitude of the protuberant element ("Apmin") and an average maximum amplitude of the protruding element ("Apmax") along a predetermined area of ​​the forming structure 8. Similarly, for variable cross-sectional dimensions, it is possible to determine an average projection diameter ("dpavg") for a plurality of projections 8. Said amplitude and other dimensional measurements can be made by any method known in the art, such as, for example. , by computer-assisted scanning microscopy and related data processing. Therefore, an average dimensional relationship of the protruding elements 10, ("ARpavg") for a predetermined part of the forming structure 8 can be expressed as hpavg // dpavg. The dimensions hp and dp for the protuberant elements 10 can be determined indirectly from the known specifications for manufacturing the forming structure 8, as described more fully hereinafter.

In one embodiment, a ratio of the average hpavg height of the protruding elements differentiated to the thickness of the precursor band is at least about 1: 1, at least about 2: 1, at least about 3: 1, at least about 4: 1, or at least about 5: 1. This relationship may be important to ensure that the precursor band is sufficiently elongated, so that it is permanently deformed to create a stamped band of the present invention, especially under desirable process conditions and speed.

Fig. 3 is a top view of an embodiment of a forming structure of the present invention. The forming structure comprises a plurality of differentiated protuberant elements 10 that are completely surrounded by an intermediate area 16.

Differentiated protruding elements of the forming structure may have distal ends that are flat, rounded or sharp, depending on whether it is desired to produce a stamped band having differentiated extended elements with distal ends that are open (requiring a sharper protruding element on the structure forming) or closed (requiring a rounded protuberant element on the forming structure). The rounded distal ends of the differentiated protruding elements of the forming structure may have a given tip radius such as, for example, from about 5 micrometer to about 150 micrometers, from about 10 micrometers to about 100 micrometers, from about 20 to about 75 micrometers , or from about 30 micrometers to about 60 micrometers.

The side walls of the differentiated protuberant elements may be completely vertical or may be narrowed. In one embodiment, the differentiated protuberant elements have narrowed side walls, since the narrowed side walls can allow the band to separate more easily from the forming structure after stamping. In one embodiment, the side walls will typically have a degree of narrowing of about 0 ° to about 50 °, about 2 ° to about 30 °, or about 5 ° to about 25 °.

Fig. 4 shows a sectional view of an embodiment of differentiated protuberant elements 10 of a forming structure 8, wherein the round distal ends 14 of the differentiated protuberant elements 10 have a tip radius of approximately 46 micrometers (0.0018 inch ). The side walls of the protuberant elements 10 have a degree of narrowing of approximately 11 °.

Fig. 5 is a photomicrograph of a forming structure comprising a plurality of differentiated protruding elements having the dimensions shown in Fig. 4.

In one embodiment, the diameter of the protuberant elements 10 is constant or decreases with increasing amplitude. As shown in Fig. 2, for example, the diameter, or the greater lateral transverse dimension of the protuberant elements 10 has a maximum value near the first surface 12 and steadily decreases to the distal end 14. It is believed that this structure is desirable to help ensure that the patterned web can be easily removed from the forming structure 8.

Differentiated protuberant elements of the forming structure may comprise various different cross-sectional shapes, such as generally column or non-column forms, including circular, oval, square, triangular, hexagonal, trapezoidal, crest, pyramidal, dummy shapes. snow, mushroom, spherical, hourglass, and the like, and combinations thereof.

The forming structure 8 can be made of any material that can be shaped to have protruding elements 10 that have the dimensions necessary to manufacture a stamped band of the present invention, is dimensionally stable in the process temperature ranges reached by the forming structure 8, has a tensile modulus of at least about 30 MPa, at least about 100 MPa, at least about 200 MPa, at least about 400 MPa, at least about 1000 MPa, or at least about 2000 MPa; an elastic limit of at least about 2 MPa, at least about 5 MPa, at least about 10 MPa, or at least about 15 MPa; and a breakage deformation of at least about 1%, at least about 5%, or at least about 10%. It has been found that protruding elements with high dimensional ratios form better patterned bands since the modulus of the material of the forming structure increases, as long as it has sufficient breakage deformation (i.e., it is not too brittle) so that it is not break As for the data of the module and the elastic limit, the values ​​can be determined by tests according to known methods, and the tests can be carried out under standard TAPPI conditions, at a deformation rate of 100% / minute.

In one embodiment, the protuberant elements 10 are manufactured integrated in the forming structure 8. That is, the forming structure is manufactured as an integrated structure, removing material or building material. For example, the forming structure 8 having the protuberant elements 10 of relatively small scale can be manufactured by selective removal of material such as, for example, by chemical bite, mechanical bite or ablation through the use of high energy sources such as, for example, electric discharge machines (EDM) or lasers, or by electron beam (e-beam), or by electrochemical machining (ECM). In one embodiment, the shaping structure may be constructed by a process of stratification by photoetching generally according to the teachings of US 4,342,314.

In a method of manufacturing the forming structure 8, a base material that can be modified by laser is "laser etched" to selectively remove material to form protruding elements 10. By "which can be modified by laser", it is meant that the material can be selectively removed by laser in a controlled manner, recognizing that the wavelength used in the laser process, as well as the energy level, may need to be adjusted to the material ( or vice versa) for optimal results. Laser engraving can be achieved by known laser techniques, selecting the parameters of wavelength, energy, and time as necessary to produce the desired protuberant element dimensions. Currently known materials that can be modified by laser include thermoplastic materials such as, for example, polypropylene, acetal-type resins such as, for example, DELRIN® from DuPont, Wilmington Delaware, USA. UU., Thermostable materials such as, for example, crosslinked polyesters, or epoxides, or even metals such as, for example, aluminum, copper, brass, nickel, stainless steel, or alloys thereof. Optionally, thermoplastic and thermosetting materials can be filled with particulate or fiber charges to increase compatibility with lasers of certain wavelengths of light and / or improve the modulus or toughness to make the protruding elements 10 more durable. For example, certain polymers, such as PEEK, can be laser machined at a higher resolution and speeds if the polymer is loaded uniformly with sufficient amounts of hollow carbon nanotube type fibers.

In one embodiment, a forming structure can be laser machined in a continuous process. For example, it is possible to use as a base material a polymeric material, such as DELRIN®, of cylindrical shape, with a central longitudinal axis, an outer surface and an inner surface, the outer surface and the inner surface defining the thickness of the material of base. It can also be provided as a solid roller. It is possible to direct a mobile laser source generally orthogonal to the outer surface. The mobile laser source can move in a direction parallel to the central longitudinal axis of the base material. The cylindrical base material can rotate around the central longitudinal axis while the laser source mechanises the outer surface of the base material or makes a bite thereon in order to remove the selected parts of said base material according to a pattern that defines a plurality of distinct protruding elements. Each protuberant element may have a generally column or pillar type shape, as described herein. By moving the laser source in a direction parallel to the longitudinal axis of the cylindrical base material while said cylindrical base material rotates, it is possible to synchronize the relative movements, that is, the rotation and movement of the laser, so that, at each turn complete with the cylindrical base material, it is possible to form a predetermined pattern of protruding elements in a continuous process, similar to the "threads" of a screw.

The forming structure of the present invention can be in the form of a flat plate, a roll, a belt, a sleeve, or the like. In one embodiment, the forming structure is roll-shaped.

The lower surface of the forming structure may be, for example, porous or non-porous. For example, the bottom surface may include an opening that is sufficiently small in width that the precursor band does not deform into the opening that serves as a ventilation of the forming structure allowing air to pass through the forming structure . In one embodiment, a means is provided to allow the escape of air that may be trapped under the band. For example, a vacuum suction system can be provided to remove the air that may remain under the web, for example, by passing the air through the aeration openings of the forming structure, so that the required pressure is not increased necessary to produce the stamped band.

The lower surface of the forming structure may be, for example, porous or non-porous. For example, the bottom surface may include an opening that is sufficiently small in width that the precursor band does not deform into the opening that serves as aeration of the forming structure allowing air to pass through the forming structure . In one embodiment, a means is provided to allow the escape of air that may be trapped under the band. For example, a vacuum suction system can be provided to remove the air that may remain under the web, for example, by passing the air through the aeration openings of the forming structure, so that the required pressure is not increased necessary to produce the stamped band.

The forming structure of the present invention may also optionally comprise depressions or holes. If the forming structure also comprises depressions or holes, when used together with a static pressure plenum in a process of the present invention, the precursor band can be forced into the depressions or holes of the forming structure by means of the pressure plenum. static, so that differentiated extended elements can be formed in the precursor band extending along the surface of the precursor band located in front of the surface from which the differentiated protuberant elements are formed by the protruding elements of the forming structure. As a result, a two-sided patterned band can be created that has different designs or dimensions of extended elements on each side of the patterned band. Depending on the pressure generated between the forming structure and the static pressure plenum, as well as the geometric shapes of the protruding elements and optional depressions or holes of the forming structure, the differentiated extended elements of the stamped band may have closed distal ends or open.

Static pressure plenum

With reference to Figure 9, a static pressure plenum 36 is used to provide a force against the precursor band 34 to form the precursor band 34 according to the differentiated protuberant elements 10 of the forming structure 8. Preferably, the static pressure plenum 36 It is a static gas pressure plenum. The gas may be air, nitrogen, carbon dioxide, and the like, or combinations thereof.

The static pressure gas plenum 36 exerts pressure on the precursor band 34. The static pressure gas plenum 36 may include a hood 38 defining a plenum 40 adjacent to the precursor band 34. The cover 38 may include at least , a high pressure gas inlet 42 that allows the high pressure gas or other fluid to enter the cover 38 creating the static pressure conditions. Under conditions of static gas pressure, there is no velocity or density that affects the non-stamped precursor band 34 such as would happen with a source of velocity pressure such as an air knife. What happens, however, is that a high static gas pressure is maintained in the cover 38 that creates a pressure differential along the precursor band between the static pressure plenum 36 oriented toward the surface of the precursor band 34 and the shaping structure 8 oriented towards the surface of the precursor band 34. In one embodiment, the cover 38 may be wider than the precursor band, which may improve the closure formed with the cover 38. The pressure differential is sufficient to force the precursor band conformation 34 according to the differentiated protuberant elements 10 of the forming structure 8. The pressure differential can be improved, for example, by applying a vacuum on the forming structure 8 oriented towards the surface of the precursor band 34.

Suitable static pressure gas plenums are also described in the provisional US-patent application. __ / __, __, filed on March 11, 2010 entitled “APPARATUS FOR EMBOSSING A WEB” (P&G Case No. 11639P), and in US-5,972,280.

Precursor band

A precursor band 34 becomes a patterned band 16 according to the process of the description. Suitable precursor bands include materials that can be deformed by the pressure differential generated by the static pressure plenum 36 throughout the precursor band 34 so that the precursor band 34 conforms according to the differentiated protuberant elements 10 of the forming structure 8 for produce a patterned band 16.

The precursor band 34 typically includes synthetic material, metallic material, biological material (in particular, materials of animal origin), or combinations thereof. The precursor band 34 may optionally include cellulosic material. In one embodiment, the precursor band 34 is free of cellulosic material. Non-limiting examples of suitable precursor bands include films such as, for example, polymeric or thermoplastic films, sheets such as, for example, metal sheets (eg aluminum, brass, copper, and the like), bands comprising sustainable polymers , foams, fibrous nonwoven webs comprising synthetic fibers

(e.g., TYVEK®), collagen films, chitosan films, rayon, cellophane, and the like. Suitable precursor bands also include stratified products or mixtures of said materials.

If the precursor is a fibrous band, the fibrous band will typically have a high density so that it behaves similarly to a film material. An example of such a high density fibrous web is TYVEK®.

In one embodiment, the precursor band 34 is a polymeric film. Suitable polymeric films include thermoplastic films such as, for example, polyethylene, polypropylene, polystyrene, polyethylene terephthalate (PET), polymethylmethacrylate (PMMA), polyvinyl alcohol (PVA), nylon, polytetrafluoroethylene (PTFE) (e.g., TEFLON) or combinations thereof. Suitable polymeric films may include mixtures or mixtures of polymers.

In some embodiments, the precursor band 34 may be a band comprising a sustainable polymer such as, for example, polylactides, polyglycolides, polyhydroxyalkanoates, polysaccharides, polycaprolactones, and the like, or mixtures thereof.

The thickness of the precursor web 34 prior to stamping will typically be in the range of about 5 to about 300 micrometers, about 5 micrometers to about 150 micrometers, about 5 micrometers to about 100 micrometers, or about 15 micrometers to about 50 micrometers. Other suitable thicknesses include approximately 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, or 300 micrometers

Precursor bands, such as polymeric bands, will typically have a glass transition temperature of about -100 ° C to about 120 ° C, or about -80 ° C to about 100 ° C, or others adequate intervals. Precursor bands, such as polymer bands, can have a melting point of about 100 ° C to about 350 ° C. For example, an LDPE precursor band 34 or a mixture of LDPE and LLDPE has a melting point of about 110 ° C to about 122 ° C. A precursor band 34 of polypropylene has a melting point of approximately 165 ° C. A polyester precursor band 34 has a melting point of approximately 255 ° C. A precursor band 34 of Nylon 6 has a melting point of about 215 ° C. A PTFE precursor band 34 has a melting point of approximately 327 ° C.

In one embodiment, the process is carried out at a temperature lower than the melting point of the precursor band. For example, the process can be carried out at a temperature 10 ° C lower than that of the melting point of the precursor band. In another embodiment, the process is carried out at a temperature substantially equal to that of the melting point of the precursor band. In one embodiment, the process is carried out at a temperature higher than the glass transition temperature of the precursor band.

Optionally, the precursor band 34 may be plasticized to make it less brittle before stamping in the process.

In one embodiment, the precursor band 34 is strain hardening. The deformation hardening properties of the precursor band 34 may be desirable to facilitate the formation of the precursor band 34 according to the differentiated protuberant elements 10 of the forming structure 8. This may be preferred to produce patterned bands in which ends 24 are desired. closed distals of the extended elements 22 of the stamped band 16.

The precursor band 34 can be any material such as, for example, a polymeric film having material properties that make it suitable for being formed in the patterned strip 16 described herein by the stamping process of the description. The precursor band 34, typically, will have a creep point and the precursor band 34 preferably extends beyond its creep point to form a patterned band 16. That is, the precursor band 34 should have sufficient creep properties so that the precursor band 34 can be deformed without breaking to produce the desired differentiated extended elements 22 with closed distal ends 24 or, in the case of a stamped band 16 comprising differentiated extended elements 22 having open distal ends 24, rupture to form open distal ends 24. As described hereinbelow, the process conditions, such as temperature, can be varied for a given polymer to allow it to spread with or without rupture resulting in the embossed web 16 having the elements 22 extended. desired differentials. In general, therefore, it has been found that the preferred starting materials for use as a precursor band 34 to produce the embossed web 16 have low creep characteristics and high elongation. In addition, as previously described, the precursor bands preferably harden by deformation. Examples of films suitable for use as a precursor band 34 include low density polyethylene (LDPE) films, linear low density polyethylene (LLDPE) and mixtures of linear low density polyethylene and low density polyethylene (LDPE / LLDPE).

The precursor band 34 should also be deformable enough and have sufficient ductility to use as a precursor band 34. The term "deformable" herein describes a material that, when stretched beyond its elastic limit, substantially maintains its newly formed conformation. acquired, and has a narrowing in the distal ends 24 and / or along the side walls of the differentiated extended elements 22 of the resulting stamped band 16.

It has been found that a suitable material for use as a precursor web 34 is DOWLEX 2045A polyethylene resin, marketed by The Dow Chemical Company, Midland, MI, USA. UU. A film of this material, with a thickness of 20 micrometers, can have a tensile strength of at least 12 MPa; a tensile strength of at least 53 MPa; a maximum elongation of at least 635%; and a tensile modulus (2% Dryer) of at least 210 MPa (each of the above measurements being determined according to ASTM D 882). Other suitable precursor bands include polyethylene film having a thickness of approximately 25 micrometers (1.0 mil) and having a weight per unit area of ​​approximately 24 grams per square meter ("g / m2"), marketed by RKW US, Inc. (Rome, Georgia, USA) and polyethylene / polypropylene film having a weight per unit area of ​​approximately 14 g / m2 and a thickness of approximately 15 micrometers, marketed by RKW US, Inc.

The precursor band 34 may be a laminate of two or more bands, and may be a co-extruded laminate. For example, the precursor band 34 may include two layers, and the precursor band 34 may include three layers, referring to the innermost layer as a core layer and referring to the two outermost layers as surface layers. In one embodiment, the precursor band 34 includes a co-extruded three-layer laminated product having an overall thickness of approximately 25 micrometers (0.001 inches), the core layer having an approximate thickness of 18 micrometers (0.0007 inches); and each surface layer having an approximate thickness of 3.5 micrometers (0.00015 inches). In one embodiment, the layers may include polymers that have different stress-strain and / or elastic properties.

The precursor band 34 can be manufactured by conventional methods for producing multilayer films in conventional coextruded film production equipment. In cases where layers comprising mixtures are necessary, the microgranules of the components described above may be dry mixed first and then melt mixed in the extruder that produces said layer. Alternatively, if there is insufficient mixing in the extruder, the microgranules can be dry mixed first and then melt mixed in a pre-mix extruder, then a granulation is carried out again, before the film extrusion. Suitable methods for manufacturing precursor band 34 are described in US 5,520,875 and in US 6,228,462.

In general, the ability to form high area density (or little average center-to-center separation) the differentiated extended elements 22 on the patterned band 16 may be limited by the thickness of the precursor band 34.

In certain embodiments, the precursor band 34 may, optionally, also include a surfactant. If used, preferred surfactants include those of non-ionic families, such as: ethoxylated alcohols, alkyl ethoxylated phenols, carboxylic acid esters, glycerol esters, polyoxyethylene esters of fatty acids, polyoxyethylene esters of aliphatic carboxylic acids related to abietic acid, esters of anhydrous sorbitol, ethoxylated sorbitol esters, natural fats, natural fats, and waxes, fatty acid glycol esters, carboxylic amides, diethanolamine condensates and block copolymers of poly (alkylene oxide). The approximate molecular weights of the selected surfactants can be from 200 grams per mole to 10,000 grams per mole. Preferred surfactants have an approximate molecular weight of about 300 to about 1000 grams per mole.

If used, the level of surfactant initially mixed in the precursor band 34 may be up to 10 percent by weight of the total precursor band 34. The surfactants in the preferred molecular weight range (300-1000 grams / mol) may be incorporated at lower levels, generally about 5 percent by weight of the total of the precursor band 34 or below.

In some embodiments, the precursor band 34 may also comprise titanium dioxide in the polymer mixture. Titanium dioxide can provide greater opacity to the embossed web 16. Titanium dioxide can be incorporated up to 10 percent by weight of the precursor web 34, like low density polyethylene.

It is possible to add other additives such as a particulate material, e.g. eg, skin treatment products in the form of particles or protective materials, or anti-odor active substances, e.g. eg, zeolites, in one or more layers of the precursor band 34. In some embodiments, the patterned bands comprising particulate material, when used in applications in contact with the skin, may allow the active substances to come into contact with the skin in a very direct and effective manner. Specifically, in some embodiments, the formation of differentiated extended elements 22 may expose the matter in the form of particles located at the distal ends 24 thereof. Therefore, it is possible to arrange active substances such as, for example, skin care agents, at or near the distal ends 24 of the differentiated extended elements 22 to allow direct contact with the skin of said agents for skin care when the printed band 16 is used in applications in contact with the skin.

The average particle size of the particulate material, if used in the precursor band 34, will typically be about 0.2 to about 200 micrometers, or about 5 micrometers to about 100 micrometers. The use of certain particulate materials, such as mica interference particles, greatly improves the visual appearance of the embossed web 16.

The precursor band 34 may also optionally include colorants such as, for example, pigment, lacquer, toner, dye, ink or some other agent used to transmit color to a material, to improve the visual appearance of the printed strip 16.

Suitable pigments herein include inorganic pigments, teenage pigments, interference pigments, and the like. Non-limiting examples of suitable pigments are talc, mica, magnesium carbonate, calcium carbonate, magnesium silicate, magnesium aluminum silicate, silica, titanium dioxide, zinc oxide, oxide red iron, yellow iron oxide, black iron oxide, carbon black, ultramarine blue, polyethylene powder, methacrylate powder, polystyrene powder, silk powder, crystalline cellulose, starch, titanated mica, titrated iron oxide mica, bismuth oxychloride and the like.

Appropriate colored bands are described in the codependent application US- __ / __, __, filed on March 11, 2010 entitled “COLORED WEB MATERIAL COMPRISING A PLURALITY OF DISCRETE EXTENDED ELEMENTS” (P&G Case No. 11634) and in the application US- __ / __, __, filed on March 11, 2010 entitled “WEB MATERIAL EXHIBITING VIEWING-ANGLE DEPENDENT COLOR AND COMPRISING A PLURALITY OF DISCRETE EXTENDED ELEMENTS” (P&G Case No. 11635).

The precursor band 34 may also, optionally, contain fillers, plasticizers, and the like.

Stamped band

The precursor band 34 is processed according to the process of the description to form a patterned band 16 that can have various structural characteristics and desired properties such as, for example, desired soft manual touch and an aesthetically pleasing visual appearance. The precursor band 34 is placed between the forming structure 8 and the static pressure plenum 36 provided to form the precursor band 34 according to the protuberant elements 10 of the forming structure 8. With reference to Figure 6, a stamped band 16 having differentiated extended elements 22 is produced. As shown in Figure 7, the differentiated extended elements 22 have open proximal ends 30 and open distal ends 24 (as shown in Figure 8) or closed (as shown in Figures 6 and 7).

In one embodiment, the patterned web 16 resulting from the process described herein may have a structure 10 similar to that described in detail in US-7,402,723 or US-7,521,588.

The three-dimensional patterned band 16 is produced from a precursor band 34, which can be a layer of band material or a co-extruded material of the multilayer type or a stratified band-shaped material as described hereinbefore. Layered film materials can be coextruded, as is known in the art, to make laminated films, including films comprising surface layers. In the embodiment illustrated in Figure 6, the precursor band 34 is a layer-shaped laminated film comprising a first layer 18 and a second layer 20.

The differentiated extended elements 22 are formed as protruding extensions of the band, generally on a first surface 26 thereof. The number, size, and distribution of the extended elements 22 on the patterned band 16 can be determined based on their desired soft touch, sound effects and visual effects. For applications such as, for example, a top sheet, backing sheet or wrapping of protective paper of the adhesive in disposable absorbent articles, or in packaging, it may be desired that the differentiated extended elements 22 protrude only with respect to a surface of the embossed web 16 . Therefore, when the patterned strip 16 is used as the top sheet in a disposable absorbent article, the patterned strip 16 may be oriented so that the differentiated extended elements 22 are in contact with the skin to obtain an impression of superior smoothness. In addition, having differentiated extended elements 22 with closed distal ends 24 may result in less rewetting, that is, a smaller amount of liquid that re-penetrates the surface of the topsheet after having first passed through holes in the sheet upper towards lower absorbent layers.

With reference to Figure 7, the differentiated extended elements 22 can be described as protuberant with respect to a first surface 28 of the stamped band 16. As such, the differentiated extended elements 22 can be described as integral parts of the precursor band 34, and shaped by the permanent local plastic deformation of the precursor band 34. The differentiated extended elements 22 can be described as elements having a wall or side walls 28 defining an open proximal part 30 and a closed or open distal end 24. The differentiated extended elements 22 each have a height h measured from a minimum amplitude Amin between adjacent extended elements to a maximum amplitude Amax at the closed or open distal end 24. The differentiated extended elements 22 have a diameter d which, for a generally cylindrical structure 10, is the external diameter in a lateral cross section. By "lateral" is generally understood parallel to the plane of the first surface 26. For differentiated extended elements 22, generally in the form of a column with non-uniform lateral cross sections and / or non-cylindrical structures of differentiated extended elements 22, the diameter d is measured as the average lateral cross-sectional dimension at ½ of the height h of the element spread differentiated. Therefore, for each extended differential element a dimensional h / d ratio can be determined. The differential extended element may have a dimensional ratio h / d of at least about 0.2, at least about 0.3, at least about 0.5, at least about 0.75, at least about 1, at least about 1.5, at least about 2, at least about 2.5,

or at least about 3. The differentiated extended elements 22, typically, will have a height h of at least about 30 micrometers, at least about 50 micrometers, at least about 65, at least about 80 micrometers, at least about 100 micrometers, at least about 120 micrometers, at least about 150 micrometers, or at least about 200 micrometers. The elements typically extended will be at least the same height as the thickness of the precursor band or at least 2 times the thickness of the precursor band or, preferably, at least 3 times the thickness of the precursor band. The differentiated extended elements 22, typically, will have a diameter d of about 50 micrometers to about 5000 micrometers, about 50 micrometers to about 3000 micrometers, about 50 micrometers to about 500 micrometers, about 65 micrometers to about 300 micrometers, or from about 75 micrometers to about 200 micrometers. In certain embodiments, differentiated extended elements 22 may have diameters d greater than about 2.5 centimeters, up to about 2 centimeters, up to about 1.5 centimeters, up to about 1 cm, up to about 0.5 centimeters, or up to about 0.1 centimeters.

For differentiated extended elements 22 that are generally not column-shaped or irregularly shaped, a diameter of the extended element can be defined as twice the turning radius of the extended element differentiated at ½ of the height.

For differentiated extended elements that have shapes such as ridges, which extend longitudinally along the entire band-shaped material so that the extended elements have a part of the side walls of the extended elements that are open , a diameter of a differentiated extended element can be defined as the minimum average separation between two opposite side walls of the element extended at ½ of the height.

In general, because the actual height h of any differentiated extended element can be difficult to determine, and because the actual height can vary, an average height havg of a plurality of differentiated extended elements 22 can be determined by determining a minimum average amplitude. Amin and a minimum average amplitude Amax along a certain area of ​​the embossed band 16. Typically, said average hpavg height will be included in the height ranges described above. Similarly, for variable cross-sectional dimensions, it is possible to determine an average diameter davg for a plurality of differentiated extended elements 22. Typically, such average diameter davg will be included in the diameter ranges described above. Said amplitude and other dimensions can be measured by any method known in the art such as, for example, computer scanning microscopy and data processing. Therefore, an average dimensional ratio ARavg of the differentiated extended elements 22 for a predetermined part of the embossed web 16 can be expressed as havg // davg.

In one embodiment, the diameter of a differentiated extended element is constant or decreases with increasing amplitude (the amplitude increases to a maximum value at the closed or open distal end 24). The diameter, or average lateral transverse dimension, of the differentiated extended elements 22 may have a maximum value in the proximal part, and the lateral transverse dimension continuously decreases at the distal end. It is believed that this structure 10 is desirable to help ensure that the embossed web 16 can be easily removed from the forming structure 8. In another embodiment, the diameter of the differentiated extended elements 22 increases with increasing amplitude. For example, differentiated extended elements 22 may be shaped like a mushroom.

The narrowing of the precursor band 34 can occur due to the relatively deep stretching required to form differentiated extended elements 22 with high dimensional relationship. For example, narrowing can be observed at the closed or open distal ends 24 and / or along the side walls. By "observing" it is meant that narrowing is differentiable when viewed in enlarged cross-section. Such thinning can be advantageous, since the thinned parts offer little resistance to compression or shear when coming into contact with a person's skin. For example, when a person touches the printed band 16 on the differentiated extended elements 22 that have faces, the fingertips of the person first come into contact with the closed or open distal ends 24 of the differentiated extended elements 22. Due to the high dimensional ratio of the differentiated extended elements 22, and the narrowing of the wall of the precursor band 34 at the distal ends 24 and / or along the side walls, the differentiated extended elements 22 offer little compression resistance or shear applied on the printed band 16 by the person's fingers. This lack of resistance is reflected as a sensation of softness, very similar to the sensation of a velvet fabric.

The narrowing of the precursor band 34 at the closed or open distal ends 24 and / or along the side walls can be measured with respect to the thickness of the precursor band 34 or with respect to the thickness of the intermediate area that completely surrounds the extended elements 22 differentiated from the printed band 16. The precursor band 34, typically, will have a narrowing of at least about 25%, at least about 50%, or at least about 75% with respect to the thickness of the precursor band 34. The precursor band 34 will typically have a narrowing of at least about 25%, at least about 50%, or at least about 75%, at least about 85% of the thickness of the intermediate area surrounding the extended elements 22 differentiated from the printed band 16.

It should be mentioned that the impermeable band that has only the differentiated extended elements 22 as described herein, and which does not have macroscopic openings or differentiated extended elements 22 having open distal ends 24, can offer smoothness for any application in which no fluid permeability is needed. Therefore, in one embodiment, the process produces a patterned band 16 that has a silky soft touch impression on at least one surface thereof, the silky feeling surface of the patterned band 16 presenting an element design 22 extended differentiated, each of the differentiated extended elements 22 being a protruding extension of the surface of the band and having a lateral wall defining an open proximal part 30 and a closed or open distal end 24, the extended elements 22 differentiated having a maximum lateral transverse dimension in the open proximal part 30 or near it.

The patterned band 16 may also have improved sound effects. For example, when handled or manipulated manually, the patterned band 16 creates less sound compared to the precursor band 34. Optionally, certain patterned designs can create differentiable, desirable sounds, when touched or rubbed.

The "area density" of the differentiated extended elements 22, which is the number of differentiated extended elements 22 per unit area of ​​the first surface 26, can be optimized, and the embossed web 16 will typically contain from about 4 to about 10,000 , from about 95 to about 10,000, from about 240 to about 10,000, from about 350 to about 10,000, from about 500 to about 5000, or from about 700 to about 3000 extended elements 22 differentiated by square centimeter. In general, center-to-center separation can be optimized for adequate tactile printing while minimizing entrapment of materials such as fluids, between differentiated extended elements 22. The center-to-center separation between differentiated extended elements 22 may be from about 100 micrometers to about 1000 micrometers, from about 30 micrometers to about 800 micrometers, from about 150 micrometers to about 600 micrometers, or from about 180 micrometers to about 500 micrometers.

When the stamped band 16 is used as the top sheet for disposable absorbent articles, the stamped band 16 can also contain macro openings that allow fluid to flow through the stamped band 16.

Process for manufacturing the stamped band

With reference again to Figure 9, The process of forming a stamped band 16 includes arranging the precursor band 34 between the static pressure plenum 36 and the forming structure 8 and applying a gas pressure from the static pressure plenum 36 against the precursor band 34 and the forming structure 8 that is sufficient to form parts of the precursor band 34 according to the differentiated protuberant elements 10 of the forming structure 8 in order to thus form a patterned band 16 having 22 differentiated extended elements. The conformation of the precursor band 34 according to the forming structure 8 can be a partial conformation, substantial conformation, or complete conformation, depending on the pressure generated and the topography of the forming structure 8. Without intending to impose any theory, it is believed that the open distal ends 24 can be formed by locally breaking the precursor band 34 while forming the precursor band 34 according to the differentiated protuberant elements 10 of the forming structure 8.

In order to obtain a permanent deformation of the precursor band 34 to form the stamped band 16, the pressure applied is generally sufficient to stretch the precursor beyond its creep point.

The process can be a discontinuous process or a continuous process. A discontinuous process may include providing individual sheets of a precursor web material 34 located between the forming structure 8 and the static pressure plenum 36.

A continuous process may include providing a roll of precursor web material 34 that is unwound and disposed between the forming structure 8 and the static pressure plenum 36. The forming structure 8 can be, for example, in the form of a roll. As the precursor band 34 passes between the roll of the forming structure 8 and the static pressure plenum 36, a stamped band 16 is formed.

The process can have relatively short residence times. Here, the term "residence time" refers to the amount of time at which pressure is applied to a given part of the precursor band 34, usually the amount of time in which a given part of the precursor band 34 is placed between the forming structure 8 and the static pressure plenum 36. The pressure is typically applied to the precursor band 34 for a residence time of less than about 5 seconds, less than about 1 second, less than about 0.5 seconds, less than about 0.1 second, less than about 0.01 second, or less than about 0.005 seconds. For example, the residence time can be from about 0.5 milliseconds to about 50 milliseconds. Even with relatively short residence times, patterned bands can be produced with the desirable structural characteristics described herein. As a result, the description process allows high-speed production of patterned bands.

The precursor band 34 can be introduced between the forming structure 8 and the static pressure plenum 36 at a speed of at least about 0.01 meters per second, at least about 1 meter per second, at least about 5 meters per second, or at least about 10 meters per second. Other suitable speeds include, for example, at least about 0.01, 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 meters per second .

Depending on factors such as, for example, the shape of the differentiated protuberant elements 10 of the forming structure 8 and of the applied pressure, the distal ends 24 of the extended elements of the printed band 16 produced by the process of the description can be both Open as closed.

The process can be carried out at room temperature, which means that heat is not intentionally applied to the forming structure 8 and / or to the precursor band 34. It should be noted, however, that heat may be generated due to the pressure between the forming structure 8 and the static pressure plenum 36, especially in a continuous process. As a result, the forming structure 8 and / or the gas of the static pressure gas plenum can be cooled to maintain the process conditions at the desired temperature, for example, at room temperature.

The process can also be carried out at an elevated temperature of the precursor band 34. For example, the temperature of the precursor band 34 may be lower than the melting point of the precursor band 34. For example, the temperature of the precursor band 34 it may be at least about 10 ° C lower than the melting point of the precursor band 34. The precursor band 34, especially a precursor band 34 that includes polyethylenes, can have a temperature during the process of about 10 ° C to about 200 ° C, about 10 ° C to about 120 ° C, about 20 ° C to about 110 ° C, from about 10 ° C to about 80 ° C, or from about 10 ° C to about 40 ° C. The precursor band 34 can be heated during the process by heating the precursor band 34, using a heated fluid pressure source for the static pressure plenum 36, and / or by heating the forming structure 8. For example, it can be used a heated gas as a pressure source for the static pressure plenum 36.

In one embodiment, the precursor band is not heated before being placed between the forming structure and the moldable substrate. In another embodiment, the precursor band, the forming structure and the movable substrate are not heated before placing the precursor band between the shaping structure and the movable substrate.

In general, the process of the present invention can be carried out at a temperature of from about 10 ° C to about 200 ° C, from about 10 ° C to about 120 ° C, from about 10 ° C to about 80 ° C, or from about 10 ° C to about 40 ° C. The temperature can be measured, for example, by a non-contact thermometer, for example, an infrared thermometer or a laser thermometer that measures the temperature in the contact line between the static pressure plenum and the forming structure 8. The temperature can also be determined using temperature sensitive material such as, for example, Thermolabel marketed by Paper Thermometer Company.

The static pressure plenum 36 provides an average pressure. The average pressure is sufficient to form the precursor band 34, which is placed between the forming structure 8 and the static pressure plenum 36, according to the differentiated protuberant elements 10 of the forming structure 8 to form a printed band 16. In general, the average pressure provided enters the forming structure 8 and the static pressure plenum 36 is about 0.1 MPa to about 25 MPa, about 1 MPa to about 20 MPa, about 0.5 MPa to about 10 MPa , from about 10 MPa to about 25 MPa, or from about 0.5 MPa to about 5 MPa.

The process may, optionally, also include the application of a sliding agent to the precursor band 34 and / or to the forming structure 8 before arranging the precursor band 34 between the forming structure 8 and the static pressure plenum 36. This can be advantageous, especially in a continuous process, to reduce friction between the precursor band 34 and the forming structure 8. Non-limiting examples of suitable slip agents include silicone, talc, lubricating oils, and the like.

The process can, optionally, be combined with other processes to further manipulate the embossed web 16. In one embodiment, said additional processes can be combined with the process on the same production line of the process to produce, for example, absorbent items. In one embodiment, the process is combined with a process that can provide macro openings to the embossed web 16, for example, the process described in US-2006/0087053 A1 or US-2005/0064136 A1. Said combination of processes can produce a band 16 stamped with macro openings that may be suitable for use as a top sheet in an absorbent article. Said embossed web 16 can subsequently be converted into an absorbent article by combining it with other components of the absorbent article such as, for example, absorbent cores, backing sheets, and the like, preferably in the same process manufacturing line.

In addition to the processes described herein above, alternative processes for manufacturing patterned bands are contemplated. The process may also include applying pressure from a second pressure source. The second pressure source can be selected from the group consisting of a static pressure liquid plenum, a static pressure gas plenum, a velocity gas pressure source such as an air knife, a source of liquid pressure at velocity, such as that used in a conventional hydroconformation process, and a moldable substrate. Provisional patent application US-61 / 159,906 describes a suitable substrate suitable for use in the process of the present description. The pressure exerted on the precursor band 34 by the second pressure source will typically be similar to the pressures exerted on the precursor band 34 by the static pressure plenum 36 described hereinbefore. The second pressure source may apply a pressure against a precursor band before or after the static pressure plenum. For example, the process may include using multiple static pressure systems. In one embodiment, at least two static pressure plenums are provided and pressure is applied on a first part of the precursor band 34 between the forming structure 8 and a first static pressure plenum. The pressure can then be applied to the first part of the precursor band 34 between the forming structure 8 and a second static pressure plenum. This may also form the part of the registered precursor band according to the same distinct protruding elements of the forming structure. This can provide an improvement of the differentiated extended elements formed by the process.

Uses of the printed band

Stamped bands can be used in a number of different ways, for example, as component materials of absorbent articles (such as, for example, top sheets, backing sheets, or wrapping of adhesive protective paper), packaging (such as wrapping a bag mode, shrink film, or plastic bags), garbage bags, food wrap, dental floss, wipes, electronic components, wall paper, clothing, aprons, window covers, placemats, book covers, and the like.

Example

The following is a non-limiting example of a process for manufacturing a patterned web of the present invention.

Example 1

Stamped bands are produced using a static gas pressure plenum and a forming structure that has approximately 1550 protruding elements differentiated by square centimeter (approximately 10,000 protruding elements differentiated by 6.45 cm2 (square inch), 100 mesh). The forming structure is made of DELRIN Acetal and has a thickness of approximately 1 mm. The differentiated protuberant elements have a height of approximately 250 micrometers, a diameter (measured at ½ of the height) of approximately 105 micrometers and a center-to-center separation of approximately 270 micrometers. The side walls of the differentiated protuberant elements are narrowed at an angle of approximately 8 °. The distal ends of the protuberant elements have diameters of approximately 88 micrometers. Differentiated protruding elements are compensated with respect to adjacent protruding elements.

The precursor band 34 used is a polyethylene film obtained from RKW US, Inc. that has a thickness of approximately 15 micrometers and has a weight per unit area of ​​approximately 14.2 grams per square meter ("g / m2").

The stamping process is carried out using a high speed research press with the forming structure at an ambient temperature of approximately 20 ° C. The high-speed research press is described in publication No. US-2009/0120308, and is designed to simulate a continuous production line process for stamping the precursor band 34. The press includes a collector plate that has a 25 mm x 25 mm opening surrounded by a rubber (40A Neoprene durometer), connected to a high pressure source to provide the pressure for the static pressure gas plenum. The forming structure is coupled to the rubber of the collecting plate up to a compression distance of approximately 1.8 mm, sealing the precursor band between the forming structure and the rubber. In this way, a pressure differential is created along the precursor band by means of the static pressure gas plenum, the face of the precursor band oriented towards the atmospheric pressure forming structure and the opposite face of the precursor band from the static pressure gas plenum at a pressure of approximately 2 MPa. The press is operated to simulate roll diameters of the 205 mm forming structure. The precursor band 34 is disposed between the forming structure 8 and the static pressure gas plenum at a simulated speed of approximately 2.74 m / s. The residence time is approximately 0.19 seconds. The resulting patterned band includes differentiated extended elements having an average height of approximately 100 micrometers and open distal ends (as shown in Figure 10A) or closed distal ends (as shown in Figure 10B).

The quantities and values ​​described herein should not be construed as strictly limited to the exact numerical values ​​mentioned. Unless otherwise indicated, each magnitude is intended to mean the mentioned value and a functionally equivalent range surrounding that value. For example, a magnitude described as "40 mm" means "approximately 40 mm."

When a technical characteristic is described herein with respect to one embodiment, this characteristic may be combined with any characteristic or features described in another embodiment or embodiments or claim or claims, unless otherwise indicated.

All documents cited in the Detailed Description of the invention are incorporated, in their relevant part, by reference herein; Mention of any document should not be considered as an acceptance that it is part of the state of the art with respect to the present invention. In the event that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document will prevail.

Although particular embodiments of the present invention have been illustrated and described, it will be apparent to the person skilled in the art that it is possible to make other changes and modifications without thereby abandoning the scope of the invention. Accordingly, the following claims are intended to cover all such changes and modifications contemplated within the scope of the present invention.