Structuring Fabric Having Long Warp Knuckles

Abstract

Described herein is an industrial fabric that exhibits favorable characteristics for the formation of a product thereon, such as tissue paper. The present invention relates to a structuring fabric that has a forming side surface and a machine side surface and comprises interwoven warp and weft yarns. The structuring fabric further comprises at least one long warp knuckle at the forming side surface and at least one weft knuckle near the forming side surface of the fabric.

Claims

1. A structuring fabric, wherein the structuring fabric is a woven fabric comprising: (a) a forming side surface and a machine side surface; (b) a plurality of machine-direction (MD) yarns; and (c) a plurality of cross-machine direction (CD) yarns arranged in first and second layers, wherein the first layer is on the forming side surface and the second layer is on the machine side surface of the structuring fabric, wherein at least a portion of the MD yarns are interwoven with the CD yarns such that the MD yarns pass over at least two of the CD yarns of the first layer, thereby forming a long warp knuckle at the forming side surface, and wherein at least a portion of the CD yarns are interwoven with the MD yarns such that the CD yarns of the first layer pass over at least one of the MD yarns, thereby forming a weft knuckle near the forming side surface of the structuring fabric.

2. The structuring fabric of claim 1, wherein the MD yarns are arranged in two or more layers.

3. The structuring fabric of claim 1, wherein the CD yarns are arranged in three or more layers.

4. The structuring fabric of claim 1, wherein the MD yarns pass over at least three CD yarns of the first layer.

5. The structuring fabric of claim 4, wherein the MD yarns pass over at least five CD yarns of the first layer.

6. The structuring fabric of claim 5, wherein the MD yarns pass over at least seven CD yarns of the first layer.

7. The structuring fabric of claim 1, wherein the CD yarns of the first layer pass over at least two MD yarns.

8. The structuring fabric of claim 7, wherein the CD yarns of the first layer pass over at least three MD yarns.

9. The structuring fabric of claim 1, comprising one or more woven and/or nonwoven machine-side layers.

10. The structuring fabric of claim 1, wherein the fabric comprises one or more pockets having a CD width of at least one MD yarn diameter.

11. The structuring fabric of claim 1, wherein the fabric comprises one or more pockets having a machine-direction (MD) length of at least one CD yarn diameter.

12. The structuring fabric of claim 1, wherein the structuring fabric is an eTAD fabric.

13. The structuring fabric of claim 1, wherein the forming side surface faces a fibrous web.

14. The structuring fabric of claim 1, wherein the MD yarns comprise a material selected from the group consisting of: carbon, polyamide, rayon, fiberglass, cotton, ceramic, aramid, polyester, metal, polyethylene, polypropylene, polycyclohexylenedimethylene terephthalate (PCT), cyclohexanedimethanol terephthalic acid (PCTA), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyetherketoneketone (PEKK), and polyethylene naphthalate (PEN).

15. The structuring fabric of claim 1, wherein the CD yarns comprise a material selected from the group consisting of: carbon, polyamide, rayon, fiberglass, cotton, ceramic, aramid, polyester, metal, polyethylene, polypropylene, polycyclohexylenedimethylene terephthalate (PCT), cyclohexanedimethanol terephthalic acid (PCTA), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyetherketoneketone (PEKK), and polyethylene naphthalate (PEN).

16. The structuring fabric of claim 1, wherein the MD yarns are between 0.20 mm-1.1 mm in diameter.

17. The structuring fabric of claim 16, wherein the MD yarns are 0.40 mm in diameter.

18. The structuring fabric of claim 1, wherein the CD yarns are between 0.20 mm-1.1 mm in diameter.

19. The structuring fabric of claim 18, wherein the CD yarns are 0.30 mm in diameter.

20. The structuring fabric of claim 1, wherein the long warp knuckle on the forming side surface has a length between 2.0 mm and 5.0 mm.

21. The structuring fabric of claim 1, wherein the weft knuckle near the forming side surface has a length between 0.40 mm and 1.60 mm.

22. The structuring fabric of claim 1, wherein a plane difference between a top surface of the long warp knuckle and a top surface of the weft knuckle is up to 0.50 mm.

23. The structuring fabric of claim 22, wherein the plane difference between the top surface of the long warp knuckle and the top surface of the weft knuckle is between 0.25 mm and 0.50 mm.

24. The structuring fabric of claim 1, wherein a plane difference between a top surface of the long warp knuckle and a top surface of the weft knuckle is between 0.05 mm and 1.0 mm.

25. The structuring fabric of claim 1, wherein the structuring fabric comprises one or more pockets having a MD length between 1.0 mm and 5.0 mm.

26. The structuring fabric of claim 1, wherein the structuring fabric comprises one or more pockets having a CD width between 0.3 mm and 2.0 mm.

27. The structuring fabric of claim 6, wherein the MD yarns pass over at least 18 CD yarns of the first layer.

28. The structuring fabric of claim 8, wherein the CD yarns of the first layer pass over at least 18 MD yarns.

29. The structuring fabric of claim 1, comprising a pocket depth wherein a plane difference between a top surface plane of a long warp knuckle or portion thereof defining a pocket length or width boundary and a top surface plane of one or more of a weft yarn, a warp yarn, a warp knuckle, or a weft knuckle defining a pocket bottom comprises a range of depths between 0.01 mm to 1.0 mm.

30. The structuring fabric of claim 1, wherein one or more of the MD and/or CD yarns is non-flat and/or non-smooth.

31. The structuring fabric of claim 1, wherein the first layer of CD yarns comprises first and second CD yarns.

32. The structuring fabric of claim 31, wherein the first CD yarns differ from the second CD yarns in diameter, shape, and/or material.

33. A structuring fabric, wherein the structuring fabric is a woven fabric comprising: (a) a forming side surface and a machine side surface; (b) a plurality of machine-direction (MD) yarns arranged in first and second layers, wherein the first layer is on the forming side surface and the second layer is on the machine side surface of the structuring fabric; and (c) a plurality of cross-machine direction (CD) yarns, wherein at least a portion of the MD yarns are interwoven with the CD yarns such that the MD yarns of the first layer pass over at least two of the CD yarns, thereby forming a long warp knuckle at the forming side surface, and wherein at least a portion of the CD yarns are interwoven with the MD yarns such that the CD yarns pass over at least one of the MD yarns of the first layer, thereby forming a weft knuckle near the forming side surface of the structuring fabric.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 is an annotated schematic of an eTAD machine.

[0033] FIG. 2 shows a top-down image of the forming side surface of a fabric of the invention.

[0034] FIG. 3 shows a top-down image of the bottom side surface (machine side) of the fabric of FIG. 2.

[0035] FIG. 4 depicts the weaving pattern of a weft yarn forming knuckles near the forming side surface of the fabric of FIG. 2.

[0036] FIG. 5 depicts the weaving pattern of a warp yarn forming a long warp knuckle at the forming side surface of the fabric of FIG. 2.

[0037] FIG. 6 shows pockets formed in the forming side surface of the fabric of FIG. 2 by long warp knuckles and weft knuckles.

[0038] FIGS. 7A and 7B are cross-sectional views of the fabric of FIG. 2.

[0039] FIG. 8 shows a delineated sheet-side pocket formed in the fabric of FIG. 2 by long warp knuckles.

[0040] FIGS. 9-10 show measurements of a plane difference in the fabric of FIG. 2.

[0041] FIG. 11 shows a top-down image of the forming side surface of a fabric according to the invention.

[0042] FIG. 12 shows a top-down image of the forming side surface of a fabric according to the invention.

[0043] FIG. 13 is an annotated schematic of a QRT process.

[0044] FIGS. 14A, 14B, and 14C depict a pocket depth measurement of the fabric of FIG. 2.

[0045] FIGS. 15A, 15B, and 15C depict a pocket depth measurement of the fabric of FIG. 2.

[0046] FIGS. 16A, 16B, 16C, and 16D depict a weaving pattern of a fabric of the invention comprising stacked shutes (first and second layers of CD yarns) and one layer of MD yarns. FIG. 16A depicts the weaving pattern of the MD yarn, which forms a long warp knuckle at the forming side surface of the fabric. FIG. 16B depicts the weaving pattern of the CD yarn in the second (machine side) layer of CD yarns. FIGS. 16C and 16D depict the weaving pattern of first and second CD yarns in the first (forming side) layer of CD yarns.

DETAILED DESCRIPTION OF THE INVENTION

[0047] The terms comprising and comprises in this disclosure can mean including and includes or can have the meaning commonly given to the term comprising or comprises in U.S. Patent Law. Terms consisting essentially of or consists essentially of if used in the claims have the meaning ascribed to them in U.S. Patent Law. Other aspects of the invention are described in or are obvious from (and within the ambit of the invention) the following disclosure.

[0048] The term yarn or yarns in the following disclosure can refer to monofilaments, multifilament yarns, twisted yarns, textured yarns, coated yarns, bicomponent yarns, as well as yarns made from stretch broken fibers, of any materials known to those ordinarily skilled in the art. Yarns can be made of carbon, polyamide, rayon, fiberglass, cotton, ceramic, aramid, polyester, metal, polyethylene, polypropylene, and/or other materials that exhibit desired physical, thermal, chemical or other properties. Further examples of suitable materials include, e.g., polyethylene terephthalate (PET), polycyclohexylenedimethylene terephthalate (PCT), cyclohexanedimethanol terephthalic acid (PCTA), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyetherketoneketone (PEKK), polyethylene naphthalate (PEN), and yarns of a modified heat-, hydrolysis-, and/or contaminant-resistant polyester of the variety disclosed in, e.g., U.S. Pat. No. 5,169,499, incorporated herein by reference.

[0049] The terms machine direction (MD) and cross-machine direction (CD) as used in the following disclosure are used in accordance with their well-understood meaning in the art. That is, the MD of an industrial fabric, such as a belt, refers to the direction that the industrial fabric moves in a manufacturing process, such as a tissue, towel, or nonwovens making process, while CD refers to a direction perpendicular to the MD of the industrial fabric.

[0050] The term forming side or sheet side of an industrial fabric refers to the side of the industrial fabric that comes into contact with, or that faces, a sheet, paper, or web product being processed thereon. The forming side surface is the surface that faces a newly formed sheet or paper web when the industrial fabric is running on a paper machine.

[0051] The term machine side or wear side of an industrial fabric refers to the opposite side of the forming side of the fabric and is the side of the fabric that comes into contact with, or that faces, a component of a machine, such as a roller in a paper machine.

[0052] A knuckle as used herein generally refers to the length of a woven warp or weft yarn constituting a top or bottom surface of a fabric that respectively crosses over (floats over) one or more adjacent weft or warp yarns in the fabric. A knuckle may be at or below the plane of a forming side or machine side surface of a fabric. A warp knuckle or MD knuckle is one where the length of yarn constituting a top or bottom surface is a warp yarn that crosses over one or more weft yarns adjacent thereto. A weft knuckle or CD knuckle is one where the length of yarn constituting a top or bottom surface is a weft yarn that crosses over one or more warp yarns adjacent thereto.

[0053] Generally, a short knuckle is where the surface yarn crosses over (floats over) one other yarn adjacent thereto, and a long knuckle is where the surface yarn crosses over (floats over) two or more yarns adjacent thereto.

[0054] A plane difference in a woven fabric of the invention may be the difference between a top of a first strand and a top of a second strand, such as a top of a warp yarn and a top of a weft yarn, in the fabric. For example, in certain embodiments, a plane difference is the difference between a top of a highest warp knuckle at the forming side surface of a fabric to a top of a highest weft knuckle at the forming side surface of the fabric.

[0055] A pocket as used herein refers to the space between knuckles or portions thereof that are adjacent one another, e.g., adjacent warp and weft knuckles. For example, a pocket may be bounded in its length by first and second weft knuckles or portions thereof and in its width by first and second warp knuckles or portions thereof, where the warp and weft knuckles are adjacent to one another. In certain embodiments, a pocket may be bounded in its length by first and second warp knuckles or portions thereof and in its width by first and second weft knuckles or portions thereof, where the warp and weft knuckles are adjacent to one another. In some embodiments, a pocket is bounded in its length by first and second warp knuckles or portions thereof and in its width by third and fourth warp knuckles or portions thereof, where the warp knuckles are adjacent to one another. In certain embodiments, a pocket is bounded in its length by first and second weft knuckles or portions thereof and in its width by third and fourth weft knuckles or portions thereof, where the weft knuckles are adjacent to one another.

[0056] In some embodiments, a pocket may be formed with a length that is defined by the distance between two weft knuckles or portions thereof and a width that is defined by the distance between two warp knuckles or portions thereof. In certain embodiments, a pocket may be formed with a length that is defined by the distance between two warp knuckles or portions thereof and a width that is defined by the distance between two weft knuckles or portions thereof. In other embodiments, a pocket may be formed with a length that is defined by the distance between a first pair of weft knuckles or portions thereof and a width that is defined by the distance between a second pair of weft knuckles or portions thereof. In yet other embodiments, a pocket may be formed with a length that is defined by the distance between a first pair of warp knuckles or portions thereof and a width that is defined by the distance between a second pair of warp knuckles or portions thereof. In some embodiments, a pocket may be formed with a length defined by two weft or two warp knuckles or portions thereof and a width defined by one warp and one weft knuckle or portions thereof. In other embodiments, a pocket may be formed with a width defined by two weft or two warp knuckles or portions thereof and a length defined by one warp and one weft knuckle or portions thereof. In yet other embodiments, a pocket may be formed with a length defined by a warp and weft knuckle or portions thereof and a width defined by a warp and weft knuckle or portions thereof.

[0057] A repeating weave pattern in a fabric of the invention may create pockets that are defined by the repeating weave pattern.

[0058] Pocket depth is a distance from the top of a highest knuckle on the top, or forming side, surface of a fabric to a point lower or lowest within the pocket. For example, the depth of a pocket may be determined based on the distance from the plane of a top surface of a highest warp knuckle at the forming side surface of a fabric to a top surface of a lowest weft knuckle within the pocket. In some embodiments, the pocket depth may be determined based on the distance from the plane of a top surface of a warp knuckle defining a length or width boundary of the pocket to the plane of a top surface of a warp or weft yarn situated below and between the knuckles or portions thereof defining the pocket length and width. In certain embodiments, a pocket depth may comprise the distance from the plane of a first top surface of a yarn making up a knuckle defining a length or width boundary of the pocket, such as a warp knuckle, to the plane of a second top surface of the same yarn where the second top surface is situated below the first top surface and below and between the knuckles or portions thereof defining the pocket length and width boundary.

[0059] In yet other embodiments, the pocket depth is a range of depths based on the distance from the plane of a top surface of a knuckle defining a length or width boundary of the pocket to the various planes of top surfaces of warps and/or wefts and/or knuckles situated below and between the knuckles or portions thereof defining the pocket length and width boundary. In further embodiments, the pocket depth is an average depth derived from a measured range of depths. In yet other embodiments, the pocket depth is a nominal depth based on a targeted range of depths. In certain embodiments, the pocket depth is the maximum measured depth of the pocket.

[0060] As described herein, the instant invention relates to an industrial fabric, such as a structuring fabric, having CD knuckles near the forming side surface of the industrial fabric and at least one long MD knuckle at the forming side surface.

[0061] More particularly, at the forming side surface of a structuring fabric of the invention are one or more long warp knuckles. Weft knuckles are typically not at the highest plane of the forming side surface of the inventive fabric but rather near the highest plane of the forming side surface, e.g., below the top surface of the long warp knuckles. This height differential between the top of the warp and weft knuckles at the forming side surface results in a plane difference in the forming side surface between the top of the long warp knuckles and top of the weft knuckles.

[0062] The present invention provides an improved structuring fabric, such as an eTAD fabric, which exhibits favorable characteristics in embodiments of the invention for the formation of tissue paper and related products. For example, an eTAD fabric comprising a support shute design according to embodiments of the invention allows for a CD knuckle higher or lower in a forming side plane to allow for better sheet transfer at a creping roll or backing roll interface. Without a CD knuckle, it may be difficult to transfer the sheet of paper at this point in manufacture. In embodiments of the invention, the addition of the CD knuckle component higher in a forming side plane of the instant industrial fabric design allows for better sheet transfer from a backing roll to the industrial fabric. The support shute design in embodiments of the invention allows a CD knuckle to be in a high enough forming side plane to facilitate sheet transfer, but yet be below the highest fabric plane enough such that it does not affect sheet softness. For example, in certain embodiments, the instant invention relates to an eTAD fabric with long MD knuckles at the forming side surface together with an addition of a CD knuckle through the addition of a support shute (weft) to the fabric to help grab a sheet off a backing roll and thereby aid in the transfer of the sheet to the eTAD fabric.

[0063] Additionally, the inventive fabric design described herein, in certain embodiments, results in a reduction in pinholes in a sheet product produced on the fabric while at the same time maintaining good sheet product transfer to the fabric.

[0064] A structuring fabric of the invention may be woven in various weave patterns, such as complex or simple, and may be a single or multi-layered fabric. Examples of weave patterns that may be employed to create a structuring fabric of the invention include a plain, twill, basket, and/or a satin weave pattern. Structured fabrics of the invention may be woven from monofilament, plied monofilament, multifilament, and/or plied multifilament yarns. Yarns used in a fabric of the invention may be extruded from any one of several synthetic polymeric resins, such as polyamide and polyester resins, used for this purpose by those of ordinary skill in the machine clothing arts.

[0065] The structuring fabric may be made as a single layer support shute or any design or weave pattern where a forming side long MD knuckle can exist with a CD knuckle in a higher plane.

[0066] In some embodiments, a fabric of the invention comprises a double layer support shute design (that is, a double layer shute design that includes an extra shute (weft) in the forming side layer of the fabric so that there are at least twice as many wefts in the top (forming side) layer as in the bottom (machine side) layer of the fabric). In certain embodiments, a fabric of the invention may comprise a double layer of wefts having a weft ratio of 2:1, 3:1, or 3:2 between the number of wefts in the forming side layer versus the wear side (machine side) layer of the fabric. In a support shute fabric design, support shutes may be added in between holes that may be present between wefts over which a warp floats and which may be considered the main wefts. The support shute will typically have a different contour to the main weft in the fabric and may differ from the main weft in any number of ways, such as material, shape, and/or diameter, e.g., crimp. For example, in certain embodiments, the support shutes will have a smaller diameter than the main shutes in the same layer.

[0067] In some embodiments, a fabric of the invention comprises a double layer support shute design comprising two layers of CD yarns and one layer of MD yarns where the first layer of CD yarns is a forming side layer and comprises first and second CD yarns that differ from one another at least by diameter and where the second layer of CD yarns is a machine side layer that comprises yarns of the same or similar diameter as the first CD yarns of the first layer. In certain embodiments, increasing the diameter of the first CD yarn over the second CD yarn of the first layer results in increased warp knuckle length at the forming side surface of the fabric, resulting in increased softness of a paper product produced thereon, such as facial tissue, bath tissue, or paper towels. In certain other embodiments, increasing the diameter of the second CD yarn over the first CD yarn of the first layer results in increased forming side warp knuckle height and pocket depth, resulting in increased caliper of a fiber-based product produced thereon, e.g., a sheet caliper will be thicker, thus having more bulk.

[0068] In certain embodiments, the fabric comprises at least one layer of MD yarns and at least one layer of CD yarns. In other embodiments, the fabric may comprise one layer of MD yarns and two layers of CD yarns. In another embodiment, the fabric may comprise two layers of MD yarns and two layers of CD yarns. In yet another embodiment, the fabric may comprise three layers of MD yarns and two layers of CD yarns. In certain embodiments, a fabric of the invention may comprise two layers of MD yarns and one layer of CD yarns.

[0069] In one embodiment, the invention provides an eTAD fabric having both good sheet transfer from a backing roll to the eTAD fabric and from the eTAD fabric to a Yankee dryer. FIG. 1 provides an annotated schematic of an eTAD machine. In certain embodiments, the CD knuckles near the forming side surface of the inventive eTAD fabric help a sheet transfer well from the backing roll to the eTAD fabric. This allows the eTAD machine to run with less breaks due to sheet transfer issues. In further embodiments, the long MD knuckle on the forming side surface of the eTAD fabric provides for good sheet transfer from the eTAD fabric to the Yankee. The long MD knuckle further provides for good sheet contact to the Yankee dryer that gives better creping off the Yankee that results in, e.g., better sheet softness. The instant invention optimizes CD knuckles and MD knuckles so that there does not need to be a compromise between the CD knuckles and the MD knuckles.

[0070] In certain embodiments, a fabric of the invention may be used in a QRT machine (Advantage QRT technology machine by Valmet). The QRT process is depicted in FIG. 13.

[0071] Additionally, in certain embodiments, the yarns in an industrial fabric of the invention can be non-flat and/or non-smooth in conformation. In certain embodiments, some yarns may be non-flat and/or non-smooth while other yarns may be flat and/or smooth. Yarns that are not smooth and/or are not flat contribute, among other things, to a technical advantage in embodiments of the invention of better sheet transfer because of a plane difference between the MD knuckles and the CD knuckles at the forming side surface of a fabric of the invention. A non-flat and/or non-smooth yarn can aid in this transfer because such yarns create a fabric surface from which sheet product fibers can be more easily plied during sheet transfer. By contrast, a flat yarn would have greater surface area for a fibrous web to lay upon and therefore could be more difficult to transfer.

[0072] The MD yarns in a fabric of the invention may be any suitable dimension. For example, the MD yarns may have a diameter of, e.g., 0.20 mm, 0.25 mm, 0.30 mm, 0.35 mm, 0.40 mm, 0.45 mm, 0.50 mm, 0.55 mm, 0.60 mm, 0.65 mm, 0.70 mm, 0.80 mm, 0.90 mm, 1.00 mm, 1.10 mm, or values in between. In certain embodiments, the MD yarns in a fabric of the invention are uniform in diameter. In other embodiments, the MD yarns vary in diameter in a single fabric. For example, some MD yarns may be 0.30 mm and other MD yarns may be 0.40 mm in diameter in a single fabric.

[0073] The CD yarns in a fabric of the invention may be any suitable dimension. For example, the CD yarns may have a diameter of, e.g., 0.20 mm, 0.25 mm, 0.30 mm, 0.35 mm, 0.40 mm, 0.45 mm, 0.50 mm, 0.55 mm, 0.60 mm, 0.65 mm, 0.70 mm, 0.80 mm, 0.90 mm, 1.00 mm, 1.10 mm, or values in between. In some embodiments, the CD yarns of the invention are uniform in diameter. In other embodiments, the CD yarns vary in diameter in a single fabric. For example, some CD yarns may be 0.30 mm and other CD yarns may be 0.40 mm in diameter in a single fabric.

[0074] In some embodiments, all of the MD yarns and all of the CD yarns have the same diameter. In other embodiments, a portion of the MD yarns and a portion of the CD yarns have the same diameter while other portions of the MD yarns and the CD yarns in the same fabric have differing diameters. In yet other embodiments, all of the MD yarns vary in diameter from all of the CD yarns.

[0075] In some embodiments, the MD yarn count in a fabric of the invention may be, e.g., 20 yarns/cm, 30 yarns/cm, 40 yarns/cm, or values in between. In other embodiments, the MD knuckle length may be, e.g., 2.00 mm, 3.00 mm, 4.00 mm, 5.00 mm, or values in between.

[0076] In certain embodiments, the CD yarn count in a fabric of the invention may be 10 yarns/cm, 20 yarns/cm, 30 yarns/cm, 40 yarns/cm, 50 yarns/cm, or values in between. In some embodiments, the CD knuckle length may be, e.g., 0.40 mm, 0.50 mm, 0.60 mm, 0.70 mm, 0.80 mm, 0.90 mm, 1.00 mm, 1.10 mm, 1.20 mm, 1.30 mm, 1.40 mm, 1.50 mm, 1.60 mm, or values in between. In other embodiments, the CD knuckle length is 1 times to 4 times the diameter of an MD warp.

[0077] In some embodiments, the plane difference between a warp and weft knuckle (measured from the plane at the top of an MD knuckle to the plane at the top of a CD knuckle) may be, e.g., 0.05 mm, 0.10 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, 0.35 mm, 0.40 mm, 0.45 mm, 0.50 mm, or values in between. In certain embodiments, the plane difference may be between 0.05 mm and 0.95 mm. In certain embodiments, the plane difference creates a pocket in the industrial fabric.

[0078] In contrast to determining a forming side surface plane difference in a fabric of the invention, pocket depth is not necessarily dependent on the placement of the highest CD knuckle at the forming side surface whereas a forming side surface plane difference is dependent on the placement of the highest CD knuckles in relation to the highest MD knuckles at the forming side surface of the fabric.

[0079] In some embodiments, one or more pockets in a structuring fabric of the invention have the same depth. In other embodiments, one or more pockets in the structuring fabric have differing depths. In yet other embodiments, some of the pockets in the structuring fabric have the same depth and other pockets in the same structuring fabric have differing depths.

[0080] In certain embodiments, a pocket length in an industrial fabric of the invention may be, e.g., 1.0 mm, 2.0 mm, 3.0 mm, 4.0 mm, 5.0 mm, or values in between. In some embodiments, all pockets in the industrial fabric have the same length. In other embodiments, all pockets in the industrial fabric have differing lengths. And in yet other embodiments, some pockets in the industrial fabric have the same length while other pockets in the same fabric have differing lengths.

[0081] In some embodiments, a pocket width in an industrial fabric of the invention may be, e.g., 0.25 mm, 0.50 mm, 0.75 mm, 1.0 mm, 1.25 mm, 1.50 mm, 1.75 mm, 2.0 mm, or values in between. In some embodiments, all pockets in the industrial fabric have the same width. In other embodiments, all pockets in the industrial fabric have differing widths. And in yet other embodiments, some pockets in the industrial fabric have the same width while other pockets in the same fabric have differing widths.

[0082] In various embodiments, fiber from a fiber-based product produced on an industrial fabric of the invention may form in different depths of a pocket in the fabric. For example, in certain embodiments, the fibers will penetrate to within certain depths of a pocket but not to within the deepest depth of a pocket, e.g., fibers may penetrate beneath the plane of a long warp knuckle at the forming-side surface of the fabric and form within depths created by the planes at the tops of wefts and/or warps found within the pocket but not form within depths created by the planes at the tops of wefts and/or warps that are the lowest points in the pocket. Thus, in certain embodiments, fibers may form in a portion of a pocket in a fabric of the invention while other portions of the pocket, e.g., the very bottom depths of the pocket, do not contain fibers from the product produced thereon.

[0083] In some embodiments, the pockets in a single fabric may generally be uniform in measurement for one or more of the plane difference between MD and CD knuckles, pocket length, and/or pocket width. In other embodiments, one or more of the plane difference between MD and CD knuckles, pocket length, and/or pocket width may vary between pockets in the same fabric.

[0084] In certain embodiments, the structuring fabric is a multi-layered fabric. For example, one or more woven or nonwoven layers can be attached to the machine-side surface of a woven fabric having near-surface CD knuckles and long MD knuckles at the forming side surface. The one or more layers added to the machine-side surface can be chemically, thermally, or mechanically attached or bonded thereto. For example, the one or more layers added can be fused, laminated, glued, or woven to the machine side of the woven fabric that has long warp knuckles at the forming side surface and weft knuckles near the forming side surface. In some embodiments, the one or more layers added to the machine side surface can be extruded meshes, knitted structures, or other nonwoven structures such as films, foils, or spunbond layers.

[0085] Turning to the figures, FIG. 2 depicts a top-down image of the forming side surface of the first or top layer of a double layer support shute fabric of the invention. As shown in FIG. 2, and according to one embodiment of the present invention, in the first layer, there is at least one MD long warp knuckle (102, 112) on the forming side surface of the fabric formed from MD yarns (e.g., 100). MD long warp knuckles (102, 112) are on a plane of the forming side surface of the fabric where a web contacts the fabric. In FIG. 2, the multiple MD long warp knuckles have a repeating pattern in the fabric. The MD long warp knuckle (102) floats, or passes, over 5 weft, or CD, yarns (103, 104, 105, 106, and 107). In the fabric of FIG. 2, CD yarns having two different diameters are used. Some CD yarns have a first diameter (103, 105, 107) while other CD yarns have a second diameter that is smaller (thinner) than the first diameter (101, 104, 106). The thinner CD yarns float over MD yarns and create a near-surface CD knuckle. For example, when the weft yarn (101) floats over two MD warp yarns, CD weft yarn (101) is in a plane near the forming side surface but is not at a highest plane of the forming side surface of the fabric. The CD yarns having a thicker diameter (103, 105, 107) weave under MD warp yarns. In FIG. 2, MD warp yarns and CD weft yarns repeat the weaving pattern of MD long warp knuckle (102) and CD weft yarn (101).

[0086] FIG. 3 shows the second layer, or bottom surface layer, of the fabric of FIG. 2. The bottom surface has an 8-shed weave pattern. The first layer (FIG. 2) and second layer (FIG. 3) are connected through an interwoven double-shute weaving pattern.

[0087] Table I below provides information concerning the yarn mesh, yarn count, air permeability, caliper, warp, shute, and support shute for the fabric of FIGS. 2 and 3 and is an exemplary double layer support shute fabric of the invention. The plane difference of this particular design is 0.316 mm based on the average of 5 different measurements from a highest forming side surface MD knuckle of the fabric to a highest forming side CD knuckle.

TABLE-US-00001 TABLE I Air Support Mesh Count Mesh Count Perm Caliper Warp Shute Shute (/in) (/in) (/cm) (/cm) (cfm) (mm) (mm) (mm) (mm) 83 53 32.5 21.0 600 2.12 0.40 0.50 0.30

[0088] The inventive fabric of FIG. 2 exemplifies a double layer support shute weave pattern having a shute ratio of 2:1 (twice as many wefts in the forming side weft layer as in the wear (machine) side weft layer) where MD yarns float over 5 CD yarns to form long MD knuckles on the top, or forming side of the fabric. In some embodiments, the shute ratio of a double layer shute weave may be, e.g., 3:1. The yarn material for the MD yarns and CD yarns of the fabric of FIG. 2 comprises a polyester. The yarns are not smooth and are not flat, which, among other things, contributes to a technical advantage of better sheet transfer through the plane difference in the forming side surface between the long MD knuckles and the CD knuckles.

[0089] The diameter of the MD yarns of the fabric in FIG. 2 is 0.40 mm. The CD yarns in FIG. 2 vary in diameter. In particular, two types of CD yarns are used, namely, one having a diameter of 0.30 mm (the support shute) and one having a diameter of 0.50 mm (the main shute).

[0090] The yarn count of the MD yarns of the fabric in FIG. 2 is 33 cm. The MD knuckle length of the fabric of FIG. 2 is nominally 4.0 mm. The yarn count of the CD yarns of the fabric of FIG. 2 is 21 cm. The CD knuckle length of the fabric of FIG. 2 is in the range of 0.5 mm-1.0 mm.

[0091] The forming side pockets in the fabric of FIG. 2 (e.g., such as the pockets shown in FIG. 6) have a nominal plane difference of 0.25 mm. The nominal 0.25 mm plane difference was determined based on the average of at least 5 measurements from the top of a highest MD knuckle to the top of a highest CD knuckle on the sheet forming surface. The pocket length of a pocket in FIG. 2 (e.g., pockets as shown in FIG. 6) is nominally 2.5 mm and the pocket width is nominally 0.5 mm.

[0092] FIG. 4 shows a cross-sectional schematic of the fabric of FIG. 2. In FIG. 4, the shute pattern of shute yarn (108) is in the CD direction. FIG. 4 shows the shute (108) is woven over two MD yarns, under one MD yarn, over one MD yarn, under one MD yarn, and over two MD yarns in a repeating pattern. This weaving pattern correlates to the CD yarns with the thinner diameter (101, 104, 106) in FIG. 2.

[0093] FIG. 5 shows a cross-sectional schematic of the fabric of FIG. 2. In FIG. 5, the weave pattern of MD warp yarn (100) is shown in the MD direction. That portion of MD warp yarn (100) forming a long warp knuckle (112) on the forming surface side of the fabric is also shown.

[0094] FIG. 6 shows the forming side surface of the fabric of FIG. 2 and three exemplary pockets. Each pocket shown (109, 110, 111) is created by the boundaries of portions of two MD long warp knuckles at the fabric surface and portions of two CD weft knuckles adjacent thereto near the fabric surface. The three exemplary pockets (109, 110, 111) are delineated by shaded regions in FIG. 6. The pocket MD length is 3 CD yarn diameters (two main shutes and one support shute) plus the spaces between the CD yarns bounded by the weft knuckles. The pocket CD width is 1 MD yarn diameter plus the spaces (e.g., on the right and left side of the MD yarn) bounded by the long warp knuckles.

[0095] FIGS. 7A and 7B show a cross-sectional view along the MD of the fabric of FIG. 2. FIGS. 7A and 7B show smaller, white monofilaments (117) that are support shutes located at the forming side of the fabric, and the dotted box in FIG. 7B outlines an exemplary pocket of FIG. 7A that is bounded in its length by CD knuckles. The plane difference shown in FIG. 7B (119) is approximately 0.50 mm and is the difference between the top of an MD knuckle (116) and the top of each of two different CD knuckles at similar forming side surface heights (117 and 118). More particularly, the plane difference between the top of the MD knuckle (116) and first CD knuckle (117) is approximately 0.50 mm and likewise, the plane difference between the top of the MD knuckle (116) and second CD knuckle (118) is also approximately 0.50 mm. In FIGS. 7A and 7B, the plane difference of the surface long warp and CD knuckles may also be determined based on the average of the difference in distance between, e.g., the top plane of the MD knuckle 116 and the top planes of each of CD knuckles 117 and 118. This plane difference measurement of approximately 0.50 mm was one of the 5 values used when determining the nominal 0.25 mm plane difference of FIG. 2 discussed above based on averaging at least 5 measurements from the top of a highest MD knuckle to the top of a highest CD knuckle on the sheet forming surface.

[0096] When considering pocket depth, the bottom measurement for determining the pocket depth may include a range of measurements to allow for variation in the lowest planes associated with different yarns constituting a bottom of a pocket. For example, while the top plane of the pocket may be readily determined based on the top of an MD knuckle delineating, e.g., a width of the pocket, the bottom of the pocket may be determined based on a range of planes measured from the top of different warps, wefts, and/or knuckles situated below and between the knuckles delineating the length and width boundaries of the pocket.

[0097] FIG. 8 shows a delineated pocket in the forming side surface of the fabric of FIG. 2 (FIGS. 7A/7B) that is bounded in its length and width by portions of long warp knuckles at the forming side surface.

[0098] FIGS. 9-10 show a top-down view (FIG. 9) and measurements (FIG. 10) of a plane difference in the sheet-side surface of the fabric of FIG. 2. The plane difference measured is 0.323 mm. As noted, a plane difference may be the measurement from the top of one knuckle to the top of another knuckle. Here, it is the top of a long MD knuckle to the top of a CD knuckle at the forming side surface of the fabric. In FIG. 10, the x-axis is the distance across the fabric that was measured, this distance corresponding to that of the diagonal arrow shown across the fabric in FIG. 9. The y-axis is the thickness of the fabric that was measured. The top thick, horizontal line corresponds to the highest point of the long warp knuckles, and the bottom thick, horizontal line corresponds to the highest point of the CD knuckles at the forming side surface. The plane difference of 0.323 mm shown in FIG. 10 thus corresponds to the difference between the highest point in the topmost MD knuckles and the highest point in the topmost CD knuckles measured along the distance of the FIG. 9 arrow.

[0099] FIG. 11 shows a fabric according to the invention. In FIG. 11, the MD yarns float over two CD yarns (120, 121) in a repeating pattern and form long MD knuckles (123). The MD long knuckle (123) is at the forming side surface and CD yarns (120, 121) interweave to form respective CD knuckles (115, 133) near the forming side surface.

[0100] FIG. 12 shows a fabric according to the invention. In FIG. 12, the MD yarns float over three CD yarns (124, 125, 126) in a repeating pattern and form long MD knuckles (127). The long MD knuckle (127) is at the forming side surface and CD yarns (124, 125, 126) interweave to form CD knuckles near the forming side surface. For example, CD yarn 124 forms knuckle 128 near the forming side surface of the fabric.

[0101] FIGS. 14A, 14B and 14C show a pocket depth measurement of the fabric of FIG. 2. Pocket depth measured in these figures is 0.91 mm and is based on the difference in distance between a highest long warp knuckle plane at the surface of the fabric and the top plane of a warp or weft at a lowest point in the pocket. In contrast to determining a forming side surface plane difference in a fabric of the invention, pocket depth is not necessarily dependent on the placement of the highest CD knuckle at the forming side surface whereas a forming side surface plane difference is dependent on the placement of the highest CD knuckles in relation to the highest MD knuckles at the forming side surface of the fabric.

[0102] Similar to FIGS. 14A, 14B, and 14C, FIGS. 15A, 15B, and 15C show a pocket depth measurement of the fabric of FIG. 2 in which the measurement is based upon a single plane difference measurement between a highest warp knuckle plane at the surface of the fabric and the top plane of a warp or weft at a lowest point in the pocket. FIGS. 15A, 15B, and 15C show a pocket depth of 1.28 mm as measured from the difference between-1.29 mm (a bottom plane measurement) and 0.01 mm (a top plane measurement).

[0103] FIGS. 16A, 16B, 16C, and 16D concern a cross-sectional view of a double layer support shute fabric of the invention comprising two layers of CD yarns and one layer of MD yarns. The first layer of CD yarns is on the forming side of the fabric and comprises first and second CD yarns where the first CD yarns (main shutes) have a larger diameter than the second CD yarns (support shutes). FIG. 16A is a view of the weave pattern in the MD of the fabric and depicts a long warp knuckle at the forming side surface that floats over five CD yarns in the first (forming side) CD yarn layer. FIGS. 16B-16D are CD views of the fabric and depict the weave patterns of the different weft yarns. FIG. 16B depicts the weave pattern of the CD yarn in the second (machine side) CD yarn layer. FIGS. 16C and 16D depict the first (16C) and second (16D) weft yarn patterns in the first (forming side) CD yarn layer.

[0104] Modifications to the above would be obvious to those of ordinary skill in the art, but would not bring the invention so modified beyond the scope of the present invention. The claims to follow should be construed to cover such situations.