EP1590527A2

EP1590527A2 - Multi-layer fabric

Info

Publication number: EP1590527A2
Application number: EP03814788A
Authority: EP
Inventors: Brian G. Majaury; Ernest Fahrer; Monique Fagon; Rita Hansson
Original assignee: Albany International Corp
Current assignee: Albany International Corp
Priority date: 2002-12-30
Filing date: 2003-12-15
Publication date: 2005-11-02
Also published as: WO2004061210A8; AU2003300929C1; AU2003300929B2; BR0317865A; NZ540278A; CA2509067C; KR20050088350A; RU2337187C2; WO2004061210A3; CA2509067A1; NO20053695L; KR101126075B1; MXPA05006467A; WO2004061210A2; RU2005117346A; AU2003300929A1; BR0317865B1

Abstract

A fabric having top and bottom layers, with each layer having machine direction (MD) yarns and cross-direction (CD) yarns interwoven together. The fabric includes pairs of binder yarns that bind together the top and bottom layers. The binder pairs are interwoven so as to be an integral part of the first layer and contribute to a structure thereof. The binder pairs are a non-integral part of the second layer and do not contribute to d structure thereof. During a repeat pattern, at least one of the two binder yarns of a binder pair is integrally woven with the yarns of the first layer and passes over outer surfaces of, two non-consecutive yarns in the second layer. As a result, a 'double knuckle' binding structure may be formed which improves integrity of the resulting composite fabric by reducing the length of the binder yarn path through the fabric.

Description

MULTI-LAYER FABRIC

Held of the Invention

The present invention relates generally to papermaking technology, and more specifically, to fabrics for use with a papermaking machine.

Description of the Prior Art

During the papermaking process, a cellulosic fibrous web is formed by depositing a fibrous slurry, that is, an aqueous dispersion of cellulose fibers, onto a moving forming fabric in the forming section of a papermaking • machine. A large amount of water is drained from the slurry through the forming fabric, leaving the cellulosic fibrous web on the surface of the forming fabric.

The newly formed cellulosic fibrous web proceeds from the forming section to a press section, which includes a series of press nips. The cellulosic fibrous web passes through the press nips supported by a press fabric, or, as is often the case, between two such press fabrics. In the press nips, the cellulosic fibrous web is subjected to compressive forces which squeeze water therefrom, and which adhere the cellulosic fibers in the web to one another to turn the cellulosic fibrous web into a paper sheet. The water is accepted by the press fabric or fabrics and, ideally, does not return to the paper sheet.

The paper sheet finally proceeds to a dryer section, which includes at least one series of rotatable dryer drums or cylinders, which are internally heated by steam. The newly formed paper sheet is directed in a serpentine path sequentially around each in the series of drums by a dryer fabric, which holds the paper sheet closely against the surfaces of the drums. The heated drums reduce the water content of the paper sheet to a desirable level through evaporation. The forming, press and dryer fabrics all take the form of endless loops on the paper machine and function in the manner of conveyors. It should further be appreciated that paper manufacture is a continuous process which proceeds at considerable speeds. That is to say, the pulp is continuously deposited onto the forming fabric in the forming section, while a newly manufactured paper sheet is continuously wound onto rolls after it exits from the dryer section.

Woven fabrics take many different forms. For example, they may be woven endless, or flat woven and subsequently rendered into endless form with a seam.

Forming fabrics play a critical role during the paper manufacturing process. One of its functions, as implied above, is to form and convey the paper product being manufactured to the press section. The forming fabric design, however, needs to address water removal and sheet formation constraints. That is, forming fabrics are designed to allow water to pass through (i.e. control the rate of drainage) while at the same time prevent fiber and other solids from passing through with the water. If drainage occurs too rapidly or too slowly, the sheet quality and machine efficiency suffers. To control drainage, the space within the forming fabric for the water to drain, commonly referred to as void volume, must be properly designed.

Contemporary forming fabrics are produced in a wide variety of styles designed to meet the requirements of the paper machines on which they are installed for the paper grades being manufactured. Generally, they comprise a base fabric woven from monofilament, and may be single-layered or multi- layered. The yarns are typically 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 paper machine clothing arts.

The design of forming fabrics additionally involves a compromise between the desired fiber support and fabric stability. A fine mesh fabric may provide the desired paper surface and fiber support properties, but such design may lack the desired stability resulting in a short fabric life. By contrast, coarse mesh fabrics provide stability and long life at the expense of fiber support and the potential for marking. To minimize the design tradeoff and optimize both support and stability, multi-layer fabrics have been developed. For example, in double and triple layer fabrics, the forming side is designed for sheet and fiber support while the wear side is designed for stability, void volume, and wear resistance.

Those skilled in the art will appreciate that fabrics are created by weaving, such that the resulting fabric has a weave pattern which repeats in both the warp or machine direction (MD) and the weft or cross-machine direction (CD). Multi-layer fabrics, such as triple layer fabrics, may loosen during use and cause unacceptable levels of abrasion within the structure. The present invention provides a fabric which alleviates or overcomes such disadvantages.

SUMMARY OF THE INVENTION In accordance with an illustrative embodiment of the present invention, there is provided a fabric useful for fabricating paper, the fabric including first and second layers, each having machine direction (MD) yarns and cross- direction (CD) yarns interwoven therewith. A plurality of binder pairs bind the first and second layers together. The binder pairs are interwoven so as to be an integral part of the first layer and contribute to a structure thereof. The binder pairs are a non-integral part of the second layer and do not contribute to a structure thereof. During a repeat pattern , at least one of the two binder yarns of a binder pair is integrally woven with the yarns of the first layer and passes over outer surfaces of two non-consecutive yarns in the second layer. As a result, a "double knuckle" binding structure may be formed which improves integrity of the resulting composite fabric by reducing the length of the binder yarn path through the fabric.

The above and other features and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments thereof. BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description, given by way of example and not intended to limit the present invention solely thereto, will best be appreciated in conjunction with the accompanying drawings, in which like reference numerals denote like elements and parts, wherein:

FIG. 1 is a cross-sectional view in the MD direction, of a portion of a first fabric depicting a binder pair in accordance with the present invention;

FIG. 2 is a cross-sectional view in the MD direction, of a different portion of the first fabric depicting cross-machine-direction (CD) yarns; FIG. 3 is a wear-side photograph of the first fabric;

FIG. 4 is a photograph of a cross-section of the first fabric in the MD direction;

FIG. 5 is a cross-sectional view in the CD direction of a portion of the first fabric depicting a lower layer; FIG. 6 is a cross-sectional view of a CD yarn arrangement of a second fabric in accordance with the present invention;

FIG 7 depicts cross-sectional diagrams showing an illustrative CD yarn weave pattern of the first fabric;

FIG 8 shows cross-sectional diagrams depicting an illustrative CD yarn weave pattern of the second fabric;

FIG. 9 is a photograph of a paper side view of the second fabric;

FIG. 10 is a photograph of a wear-side view of the second fabric;

FIGS. 11 A, 11B, and 11C are diagrams of cross-sectional views of a fabric according to another embodiment of the present invention; FIGS. 1 ID and 1 IE are respective paper side and machine side views of a fabric woven in accordance with the present invention;

FIGS. 12A and 12B are diagrams of cross-sectional views of a fabric according to a further embodiment of the present invention;

FIGS. 12C and 12D are paper side and machine side views of a fabric woven in accordance with the present invention;

FIGS. 13 A and 13B are diagrams of cross-sectional views of a fabric according to yet another embodiment of the present invention; FIGS. 13C and 13D are paper side and machine side views, respectively, of a fabric woven in accordance with the present invention;

FIGS. 14A and 14B are diagrams of cross-sectional views of a fabric according to an additional embodiment of the present invention; FIGS. 14C and 14D are paper side and machine side views, respectively, of a fabric woven in accordance with the present invention;

FIG. 15 is a diagram of cross-sectional view of a fabric according to another embodiment of the present invention;

FIG. 16 is a view of a fabric pattern according to an embodiment of the present invention;

FIG. 17A illustrates a further binder pair embodiment of the present invention;

FIG. 17B illustrates a binder pair that may be used in a fabric with the binder pair of FIG. 17 A; FIGS. 18A and 18B depict binder pairs that may be used in a fabric according to the present invention; and

FIG. 19 illustrates a further binder pair embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, there is shown a cross-sectional illustration of a binder yam pair that forms a part of a composite fabric 100 in accordance with an embodiment of the present invention. Fabric 100, which is advantageously employed in a paper-making process, is composed of an array of machine-direction (MD) yams (warp yams) and cross-machine direction (CD) yams (weft yams). MD yams such as 1-20 are arranged in two layers, with yams 1-10 arrayed in a bottom layer (or machine-side or "wear-side" layer) and ya s 11-20 arranged correspondingly in a top layer (or paper or forming side layer). CD yams PA and PB together constitute a pair of binder ya s, which are depicted in a binder pair segment pattern 30 according to one embodiment of the invention. Binder yams PA, PB function to bind upper layer (LI) warp ya s to lower layer (L2) warp yams to form the composite weave fabric 100. Binding is accomplished in this embodiment by means of binder ya PA running in a cross-machine direction path that interweaves a number of warp yams in the top layer LI, then crosses to lower layer L2 and interweaves a number of lower layer warp yams, and subsequently crossing back to the upper layer to repeat the same or similar pattern. Likewise, binder yam PB, which may run parallel and adjacent to binder ya PA, or intertwined with yarn PA, binds upper and lower layer warp yams in a similar fashion, and is preferably complementary to yam PA. That is, by suitably arranging the crossing points of binder yams PA and PB, a substantially uniform top side layer surface can be achieved, which is preferable for use as a paper side layer. As a result, the binder yam pair 30 makes up a part of the structure of the top layer LI, whereby the binder pair can be considered an "intrinsic" type of binder pair which is an integral part of the top layer so as to contribute to a structure of the top layer. The binder pair, however, can be considered a non- integral part of the bottom layer so as not to contribute to a structure of the bottom layer. (It is noted here that in other embodiments of the invention, binder yam pairs such as PA, PB can run in the MD direction to accomplish binding, instead of the CD direction.) In the fabric portion illustrated in FIG. 1, two "repeat patterns" are shown, Where the first comprises the portion of yams PA and PB that bind the 20 warp yams 1-20. The second repeat pattern binds MD yams 1' to 20'. Each repeat pattern may be considered as encompassing ten "columns" of warps, with two layers per column, and two CD binder yams PA, PB, together constituting at least a portion of a "row" of wefts in both layers. Further, binder ya s PA and PB may run in the CD direction closely to one another such that, when viewed from the top of fabric 100, the binder yams PA and PB substantially overlay one another, i.e., they are nearly vertically aligned. Note that the use of the terms "columns" and "rows" herein is used for convenience of explanation , and is not intended to limit the invention to MD yams and CD yams that are necessarily orthogonal; for example, it is possible for the MD yams to be skewed relative to one another. The warp yams may be substantially uniform in cross section and spacing in the upper and lower layers, such as the illustrated yams 1-20, although it is quite possible to employ warp yams of differing cross section and shapes (e.g., cylindrical, elliptical, non-round or rectangular cross section) in the upper and lower layers. In the CD direction, the weft yams may be arranged with differing patterns in successive rows, and the differing patterns may be designed to repeat every N rows, as will be discussed later. The CD yarns may have the same or different shapes and diameters as the warp ya s, and may be composed of the same or different material. A characteristic feature of the binder yarn pair 30 is the formation of

"double knuckle" structures such as DK1 or DK2. That is, a double knuckle DK2 is formed as yam PA forms loops (knuckles) around outer surfaces of two non-consecutive warp yams, 7 and 9, while crossing to above yam 15 on one side and above yam 11 ' on the other side. The double knuckle DK1 is likewise formed between yams 2 to 4. Note that the illustrative double knuckles DK1 and DK2 are formed such that the two non-consecutive yams that they loop around (e.g., ya s 7 and 9) have only one yam (e.g., ya 8) in the machine layer between them having an outer (bottom) surface of which the binder yam does not pass over. It is contemplated, however, that in other binder embodiments of the present invention, more than one machine layer yam can exist in between the "knuckles" of the double knuckle structure.

In any event, the double knuckle structure improves integrity of the resulting composite fabric by reducing the length of the binder yam path through the fabric. That is, the structure results in short "internal floats" for the binder yams. Better contact between the layers is achieved as compared to conventional designs, causing less contact yam to yam, and consequently less internal wear. Another effect is that the binder becomes more symmetric and therefore counteracts curling that can otherwise be a problem. The double knuckle is also locked into place in the second layer due to increased contact with multiple MD ya s. This differs from a conventional binder yam which has some freedom to slide along a single MD yam. Moreover, the double knuckle improves fabric seam strength. The binder material is often a medium to high shrinkage material, while the backside shutes (e.g., weft WI in layer L2 to be described below) are low shrinkage as standard. In the prior art, that combination results in significant curling. To balance the materials a more shrinkable bottom material can be used in embodiments of the present invention. In this case, the external wear resistance on the backside is, however, influenced negatively (less plain difference warp/shute). To compensate for the loss an alternative backside pattern with longer (e.g., 10-shed) floats can be used.

The binders used in the present invention can have "internal floats" that have a short or minimal length. The term internal float as used herein refers to the distance that a yam travels in between upper and lower warp ya s of a composite fabric such as when crossing between the upper and lower layers of the composite fabric. By utilizing a short internal float for each binder, the reliability of the resulting composite fabric may be improved. In the embodiment of FIG. 1, for example, -binder yam PA interweaves warp yams 11 through 15 by passing over yam 11, under yam 12, over 13, under 14 and over 15. Yam PA then crosses from top layer LI to bottom layer L2 by traveling between the two layers a distance (in the cross-machine direction) corresponding to one warp yam plus a short distance on either side. Thus, an internal float FI of binder yam PA can be considered the distance the yam travels between only one top and bottom MD yam (which are in the same column in this embodiment), such as between yams 6 and 16, plus a short inter-yam distance on either side of these warp yams.

Binder yam PB, in the embodiment of FIG. 1, has a longer internal float, i.e., float F2, than the internal float FI of yam PA. That is, binder ya PB interweaves warp yams 1-4, then crosses from bottom layer L2 to top layer LI by traveling from beneath yam 4 to the internal region between yams 5, 15 and then between yams 6, 16, before arriving above yam 17. Ya PB then interweaves yams 17 through 20. Hence the internal float F2 of yam PB is the CD distance in the internal region traversed between yams 5 and 15 as well as between yams 6 and 16, plus the short inter-yam distances on either side. Thus, internal float F2 has a length corresponding to two warp yams (plus a short inter-yam distance on both sides).

The binder yam pair pattern 30 with the above-described internal float design, lends uniformity to the top surface of layer LI (typically the paper side surface). That is, yam PA interweaves top layer warp yams 11-15 such that alternating yams 11, 13 and 15 are beneath the binding yam PA, and then yam PB interweaves top layer yams 17-20 such that alternating yarns 17 and 19 are beneath ya PB. As a result, alternating ya s 11, 13, 15, 17 and 19 are beneath the binding pair yams, whereby a substantially continuous plain- weave type stitching pattern on the top surface is obtained. The binder yam pair 30 can be considered as an integral part of the top layer LI surface so as to contribute to the structure thereof. However, binder yam pair 30 is not considered an integral part of the bottom layer L2 surface, so as not to contribute to the structure thereof, as will become apparent below. FIG. 2 illustrates a cross-sectional view showing weft (CD) yams WI and W2 of fabric 100. These yams together run in a repetitive weave pattern 50 interweaving warp ya s 1-20. Weft ya W2 interweaves only the top yams 11-20 whereas weft yam WI interweaves only the bottom yams 1-10. As seen in the photograph of FIG. 3, showing an illustrative wear-side (bottom) view of fabric 100, weft yams WI and W2 can run interspersed with binder yam pairs 30. In the shown embodiment, lower layer weft yams WI are thicker than top layer weft yams W2. (Only the wear side yams WI are clearly visible in FIG. 3).

With segment pattern 50 of FIG. 2, yam WI travels in a path that runs over MD yam 1, beneath MD yams 2-5, over MD yam 6 and beneath MD yams 7-10. Thus, the pattern of yam WI passes over (or "contours around") single warp yams, such as yams 1 and 6, every five yams. The pattern can be varied such that yam WI passes over every Nth warp yam, where N is more or fewer than five. Also, yarn WI may pass over plural consecutive warp yams rather than a single warp yam as shown. It is noted that the cross-sectional area, shape (e.g., circular, elliptical, non-round, rectangular) and material used for yam WI may be the same as, or different than, that used for the CD binder yams described earlier.

The yams of FIGS. 1 and 2 are combinable into a composite fabric that has a 2: 1 shute ratio. An exemplary total fabric containing these yam patterns is discussed below in reference to FIG. 7.

FIG. 4 is a photograph of a cross section of illustrative fabric 100, depicting a typical relationship between weft yams WI, W2, binder yams PA, PB and warp yams 1-20. Weft yam WI is significantly larger than the other weft yams in this embodiment. As a result, the thickness of bottom layer L2 is greater than that of top layer LI , whereby the bottom layer L2 is durable for the machine side of the paper making process. It is further apparent that due to the interweaving of yam WI and the binder yams PA, PB, the bottom layer warp ya s 1-10 are no longer horizontally aligned as previously depicted in FIG. 1. On the other hand, the top layer LI warp yams 11-20 remain neatly aligned, whereby a substantially uniform top layer surface is attained.

FIG. 5 is a cross-sectional view in the CD direction of a portion of fabric 100 depicting the lower layer L2. As seen in the figure, the MD yams of fabric 100 such as yam 1 do not run continuously in a horizontal plane. Rather, they dip down periodically as at points A and B due to the interweaving of the bottom layer weft yams WI . In the MD direction, it is seen that binder yams as PA can be alternatingly interspersed with weft yams WI.

Referring now to FIG. 6, an alternative weft ya arrangement/pattern 60 is shown which can be used in place of weft yam arrangement 50 of FIG. 2 described above. That is, the yams of FIGS. 1 and 6 may be combined to form an alternative embodiment of a composite fabric. (An exemplary full fabric containing these yams is illustrated in FIG. 8 which is discussed below.) Weft yam arrangement 60 differs by the addition of a third weft yam, W3, that runs adjacent to yam W2 and interweaves the top layer warp yams 11-20. Weft yam W3 runs in a complementary fashion to yam W2 around warp yams 11- 20. For example, yam W2 ns under yam 12, over yam 13, etc., while yam W3 runs over yam 12, under yam 13, and so on. Although weft yam W3 is illustrated with dashed lines for clarity, it is understood that this yam can be similar or identical in composition and dimensions to weft yam W2. In the cross section of FIG. 6, binder yam pairs 30 are not shown for clarity; however, in a typical arrangement, one weft yam arrangement 60 is employed in conjunction with one binder pair 30 to realize a 3: 1 shute ratio. That is, three yam patterns in the top layer are employed for every weft yam WI in the bottom layer, with the three top layer yam patterns comprising yam W2, yam W3 and the yarns PA, PB of binder pair 30. This 3:1 shute arrangement will be described further below in connection with FIGS. 8-10. Referring now to FIG. 7, there is shown an illustrative embodiment of a larger section of composite fabric 100. These figures illustrate an example of a row by row weft pattern layout illustrated in cross-sectional views in FIG. 7, and in a bottom view in FIG. 3. In FIG. 3, weft patterns in six rows RI to R5 are depicted; and these are seen in the cross sectional diagrams of FIG. 7 for rows RI to R5 (where the warp yam cross-sections are replaced with their actual designating numbers 11, 12, etc., for clarity of illustration).

In the exemplary weft yam sequence of FIG. 7, each row such as RI is considered to contain four CD yams, i.e., WI, W2, PA and PB. Row RI contains yams WI and W2 designated in pattern 50ι as well as binder yams PA, PB designated with pattern 30ι; and so forth. Each of the 40 yams in the sequence of FIG. 7 is also designated by a yam number Y1-Y40. In this example, the 40 yams Y1-Y40 can make up a repeat pattern in the MD direction. Thus, rows RI to R10 are sequentially deployed in the MD direction, and can be followed by another set of the same rows RI to R10, and so forth. Typically, the wear-side layer weft yam WI is thicker than the paper side layer weft yams W2 and the binder yams PA, PB, such that two paper side weave patterns, i.e., the weave pattern of yam W2 and that of binder pair 30, are employed for every wear-side yam WI.

In the successive rows RI, R2, etc., the patterns of the wear side yams WI are displaced in the CD direction. Thus, for example, in pattern 50] of row RI, yam WI loops over warp yams 1 and 6; but in pattern 50₂ of row R2, yam WI loops over warp yams 3 and 8; and so forth. In this manner, all of the bottom layer yams are interwoven. Similarly, the binder yam patterns are displaced from row to row: each repeat pattern 30ι to 30ιo can each be thought of as a different portion of the two combined repeat patterns 30 of FIG. 1. For instance, repeat pattern 30ι is the same as the pattern 30 between sheds 1-20 of FIG. 1; whereas repeat pattern 30₂ is the same as the pattern 30 between sheds 9, 19 and 9', 19' of FIG. 1. Thus, as the binding ya patterns are displaced from row to row, a complete binding of the upper and lower layers is achieved.

With reference now to FIG. 8, an alternative weft yam sequence is illustrated. This sequence differs from that of FIG. 7 in that the weft yarn arrangement 50 is replaced with the arrangement 60 shown in FIG. 6, resulting in the above-mentioned 3:1 shute ratio. In particular, three top (paper) layer weft patterns are deployed - i.e., the patterns of wefts W2, W3 and that of the paired binder 30 - for every lower layer (wear-side layer) weft ya WI. Thus, each of rows RI to R10 is considered to contain five yams, whereby a total of 50 yams Yl to Y50 are contained in each repeat pattern in the MD direction.

FIGS. 9 and 10 are paper side and wear side photographs, respectively, of an actual fabric, designated as 100a, that contains the weave* pattern sequence of FIG. 8. It is seen from the top view that each row such as RI contains three adjacent top layer weave patterns formed from yams W2, W3 and the binders PA, PB of pattern 30j. From the wear side view it is seen that each row as RI contains one bottom layer weft yam WI. Thus, each row Ri contains one weave arrangement 60i and one paired binder 30i.

In yet another variation of the present invention, double cross parallel (DCP) type binder pairs may be employed in rows or locations interspersed with any of the binder patterns and weft patterns discussed above. Such DCP type binder pairs are disclosed in U.S. Patent application S/N 10/334,166 entitled DOUBLE CROSS PARALLEL BINDER FABRIC, which patent application is incoφorated herein by reference. In a DCP binder pair, the two binders pass over at least one common (same) yam on an outer surface of a layer such as the paper side layer within a repeating pattern. Embodiments of the invention to be described below include DCP binder pairs. In particular, the below embodiments pertain to a fabric such as a triple layer fabric which may be utilized in a papermaking process. Such triple layer fabric may include a first (upper) layer and a second (lower) layer in which each of the first and second layers has a system of machine-direction (MD) yams and cross-machine direction (CD) ya s interwoven therewith. The first layer may be a paper side or faceside layer upon which the cellulosic paper/fiber slurry is deposited during the papermaking process and the second layer may be a machine side or backside layer. The first and second layers may be held together by use of a number of stitching or binding yams. Such stitching ya s may be a number of CD and/or MD yams. For example, a number of pairs of CD yams may be used wherein the two yams of each pair are located adjacent to each other and work in parallel. A pair of such CD ya s may be an integral or non-integral part of the weave pattern of either or both of the first and second layers and may also bind the two layers together. FIG. 11 A illustrates a portion or a repeating pattern of a binding pair 88. More specifically, FIG. 11 A is a cross-sectional view of a part of a fabric 100' which includes a first (paper side) layer L14 and a second (machine side) layer L16 having a plurality of MD yams 21-38 in the paper side layer L14, a plurality of MD yarns 41-58 in the machine side layer L16, and a number of binding pairs 88 each having CD yams 90 and 92 interwoven with the MD yams. As shown therein, CD yam 90 passes overMD yams 21, 24, 28, and 32 and passes under MD yams 22, 26, 31, 34 and 38 of the paper side layer LI 4, and passes under MD yam 56 of the machine side layer LI 6. CD yam 92 passes over MD yams 21, 32, and 36 and passes under MD yams 22, 24, 28, 31, 34, and 38 of the paper side layer L14, passes over MD yams 42, 44, 48, and 51 and passes under MD ya 46 of the machine layer L16.

A plurality of binding pairs 88 may be interwoven into fabric 100' as shown in FIG. 11D (which is a paper side view of the fabric) and FIG. HE (which is a machine side view of the fabric). Additionally, a number of CD pairs 66 may also be interwoven into the fabric 100' and arranged therein between adjacent ones of the binding pairs 88. Each of the CD pairs may have CD yams 62 and 64 which may be interwoven with the MD yams of the paper side layer L14 and the machine side layer L16 as shown in FIG. 1 lC. Further, a number of pairs 70 each including CD yams 72 and 74 may also be interwoven with the MD yams of the paper side layer L14 and machine side layer L16 of the fabric 100' as, for example, shown in FIG. 1 IB.

Therefore, in the fabric 100', each of the ya s 90 and 92 of the binding pair 88 passes over MD yams 21 and 32 on an outer surface of the paper side layer L14. Such type of binding pair is hereinafter referred to as a double cross parallel (DCP) type binder pair. Accordingly, the fabric 100' has two interwoven layers of CD and MD yams which are held together by a plurality of DCP type binder pairs wherein the two yams of each such binder pair pass over two MD yams on an outer surface of the paper side L14 within a repeat pattern.

Another fabric will now be described with reference to FIGS. 12A-D. FIG. 12A illustrates a portion or a repeating pattern of a binding pair

108 of a fabric 200 having a first (paper side) layer 114 and a second (machine side) layer 116. More specifically, FIG. 12A is a cross-sectional view illustrating a plurality of MD yams 120-138 in the paper side layer 114, a plurality of MD yams 140-158 in the machine side layer 116, and binding pair 108 having CD yams 110 and 112 interwoven with the MD yarns. As shown in FIG. 12A, in binder pair 108, CD yam 110 passes over MD yams 120, 128, 132, and 136 and passes under MD yams 122, 126, 130, 134 and 138 of the paper side layer 114, and passes under MD yarn 144 of the machine side layer 116. CD yam 112 passes over MD yams 120, 124, and 128 and passes under MD yams 122, 126, 130, 132, 136 and 138 of the paper side layer 114, and passes over MD yams 152, 156, and 158 and passes under MD yam 154 of the machine layer 116. A number of binding pairs 108 may be interwoven into fabric 200 as shown in FIG. 12C (which is a paper side view of the fabric) and FIG. 12D (which is a machine side view of the fabric). Additionally, a number of binder pairs 106 each having CD yams 160 and 162 may also be interwoven with the MD yams of the fabric 200 and arranged therein in an alternating manner with the binding pairs 108. Each of the binder pairs 106 (which may be referred to as a support shute binder (SSB) type) may have CD yams 160 and 162 which may be interwoven with the MD yams of the paper side layer 114 and the machine side layer 116 as shown in FIG. 12B. As illustrated in FIG. 12B, CD yams 160 and 162 do not pass over one or more same MD yams on an outer surface of the paper side layer 114. Further, a number of CD yams 170 may also be interwoven into the fabric 200 and arranged such that respective ones of CD yams 170 are located on either side of binding pairs 106 and 108 as, for example, shown in FIG. 12C. CD yams 170 may be similar to CD ya s 62 and 64 shown in FIG. 11C.

Therefore, in the fabric 200, each of the yams 110 and 112 of the binding pair 108 passes over MD yams 120 and 128 on an outer surface of the paper side layer 114. Thus, binding pair 108 is a DCP type binder pair. Accordingly, the fabric 200 has two interwoven layers of CD and MD yams which are held together by a plurality of DCP type binder pairs wherein the two yams of each such binder pair pass over two MD ya s on an outer surface of the paper side 114 within a repeat pattern. Further, the arrangement of binders in the fabric 200 enables relatively high permeability.

Another fabric will now be described with reference to FIGS. 13A-D. FIG. 13 A illustrates a portion or a repeating pattern of a binding pair

208 having a first (paper side) layer 214 and a second (machine side) layer 216. More specifically, FIG. 13A is a cross-sectional view of a part of a fabric 300 illustrating a plurality of MD yams 220-238 in the paper side layer 214, a plurality of MD yams 240-258 in the machine side layer 216, and binding pair 208 having CD yams 210 and 212 interwoven with the MD yams. As shown therein, CD yam 212 passes overMD yams 220, 224, 228, 232, and 236 and passes under MD yams 222, 226, 234 and 238 of the paper side layer 214, and passes under MD yam 250 of the machine side layer 116. CD yam 210 passes over MD yams 228 and 232 and passes under MD yams 230 and 234 of the paper side layer 214, and passes over MD yams 240, 244, 246, 256, and 258 and passes under MD yam 240 of the machine layer 216. A number of binding pairs 208 may be interwoven into fabric 300 as shown in FIG. 13C (which is a paper side view of the fabric) and FIG. 13D (which is a machine side view of the fabric).

Additionally, a number of binding pairs 206 may be interwoven in the fabric 300 and arranged therein in an alternating manner with the binding pairs 208. Each of the pairs 206 (which may be SSB type binders) may have CD yams 260 and 262 which may be interwoven with the MD yams of the paper side layer 214 and the machine side layer 216 as shown in FIG. 13B. As illustrated in FIG. 13B, CD yams 260 and 262 do not pass over one or more same MD yams on an outer surface of the paper side layer 214. Further, a number of CD yams 270 may also be interwoven into the fabric 300 and arranged such that respective ones of CD yams 270 are located on either side of binding pairs 208 and CD pairs 206 as, for example, shown in FIG. 13C. CD yams 270 may be similar to CD yams 62 and 64 shown in FIG. llC. Therefore, in the fabric 300, each of the yams 210 and 212 of the binding pair 208 passes over MD ya s 228 and 232 on an outer surface of the paper side layer 214. Thus, binding pair 208 is a DCP type binder pair. Accordingly, the fabric 300 has two interwoven layers of CD and MD yams which are held together by a plurality of DCP type binder pairs and SSB type binder pairs wherein the two yams of each DCP binder pair pass over two MD yams on an outer surface of the paper side 14 within a repeat pattern. Further, the arrangement of binders in the fabric 300 may provide a direct pass from the top to the bottom and, as such, may improve the internal wear resistance of the fabric as compared to fabrics having other arrangements. Yet another fabric will now be described with reference to FIGS. 14A-

D.

FIG. 14A illustrates a portion or a repeating pattern of a binding pair 308 of a fabric 400 having a first (paper side) layer 314 and a second (machine side) layer 316. More specifically, FIG. 14A is a cross-sectional view illustrating a plurality of MD yams 320-338 in the paper side layer 314, a plurality of MD ya s 340-358 in the machine side layer 316, and binding pair 308 having CD yams 310 and 312 interwoven with the MD yams. As shown, CD yam 312 passes over MD ya s 320, 324, and 328 and passes under MD ya s 322, 326, and 330 of the paper side layer 314, and passes under MD yam 354 of the machine side layer 316. CD yam 310 passes over MD yam 328 and passes under MD yam 330 of the paper side layer 314, and passes over MD yams 342, 344, and 346 and passes under MD yam 340 of the machine layer 316. A number of binding pairs 308 may be interwoven into fabric 400 as shown in FIG. 14C (which is a paper side view of the fabric) and FIG. 14D (which is a machine side view of the fabric).

Additionally, a number of binder pairs 306 may also be interwoven into the fabric 400 and arranged therein in an alternating manner with the binding pairs 308. Each of the binder pairs 306 (which may be SSB type binders) may have CD yams 360 and 362 which may be interwoven with the MD yams of the paper side layer 314 and the machine side layer 316 as shown in FIG. 14B. As illustrated in FIG. 14B, CD ya s 260 and 262 do not pass over one or more same MD yams on an outer surface of the paper side layer 314.

Further, a number of CD yams 370 may also be interwoven into the fabric 400 and arranged such that respective ones of CD yarns 370 are located on either side of binding pairs 306 and 308 as, for example, shown in FIG. 14C. CD yams 370 may be similar to CD yams 62 and 64 shown in FIG. 1 lC. Therefore, each of the yams 310 and 312 of the binding pair 308 passes over MD yam 328 on an outer surface of the paper side layer 314. Thus, binding pair 308 is a DCP type binder pair.

Accordingly, the fabric 400 has two interwoven layers of CD and MD ya s which are held together by a plurality of DCP type binder pairs and SSB type binder pairs wherein the two yams of each DCP binder pair pass over only one MD yam on an outer surface of the paper side 314 within a repeat pattern. As a result, the MD or warps yams may be offstacked and a symmetric binder contour may be obtained. Further, such arrangement may minimize the number of crossings, decrease the level of marking, decrease the caliper, and improve the seamability as compared to fabrics having other arrangements. In the above-described fabrics, the CD yams of the DCP type binder pairs do not cross each other as they pass below a transitional top MD yam. Instead, such yams are adjacent to each other as they pass over one or more same MD yams. Although specific patterns have been described above, the present invention is not so limited. For example, other patterns for the binder pairs such as that shown in FIG. 15 which includes a combination of DCP type binder pair and SSB binder pair within a repeat pattern. More specifically, FIG. 15 is a cross-sectional view of a part of a fabric 500 which includes a first (paper side) layer 514 and a second (machine side) layer 516 having a plurality of MD yams therein and a number of binder pairs each having CD yams 510 and 520. As shown in FIG. 15, CD yarns 510 and 520 each pass over MD yams 530 and 532. The binder pair of FIG. 15 includes a number of DCP portions 550 and SSB portions 540. FIG. 16 illustrates a weaving pattern for a fabric which may use binder pairs. Additionally, the weave patterns for the upper (paper side) layer may be plain weave pattern or other patterns. Similarly, the lower (machine side) may be woven on 4, 5, or 6 sheds, or other arrangements may be used.

FIG. 17 A illustrates in cross section yet another binder pair, 630, in accordance with the invention, which forms a part of a composite fabric 600. Binder ya s 610 and 620 together comprise binder pair 630, which binds together the yams of paper side layer LI and wear (machine) side layer L2. Binder pair 630 can be considered to provide a combination of the double knuckle structure of the binder 30 described above and the DCP binders also described above. The shown pattern of binder pair 630 can be a repeat pattern which repeats in the CD direction. Yam 610 forms a double knuckle DK around ya s 2 to 4, and this double knuckle affords the advantages mentioned earlier, e.g., improving integrity of the resulting composite fabric by reducing the length of the binder yam path through the fabric, improving fabric seam strength, etc. In addition, the co-location of binder yams 610 and 620 at locations above warp yams 11 and 17, for example, renders the binder pair a DCP-type binder with the attendant advantages. Binder pair 630 can be implemented in a composite fabric interspersed with other binders, such as with binder pair 30 shown in FIG. 17B (which is the same as the binder pair shown in FIG. 1). For instance, considering the wear side view of FIG. 3, binder pair 630 can be interspersed such that the shown pattern from top to bottom changes from 50, 30, 50, 30, 50, 30, 50, 30, ... to 50, 30, 50, 630, 50, 30, 50, 630, ... . Alternatively, binder pair 630 can be used as the sole binder type of a fabric.

FIGS. 18A and 18B illustrate binder pairs, 108 and 670, respectively, that can be employed in another fabric 680 in accordance with the invention. Thus, binders 108 and 670 n ay be utilized interspersed with one another within fabric 680, e.g., alternatingly. Binder pair 108 is the same as that discussed earlier in connection with FIG. 12 A; therefore, its description will not be repeated here. As shown in FIG. 18B, binder pair 670 contains yams 665 and 675. In the repeat pattern shown, yam 665 travels above yams 1 and 2, then passes below warp yam 3, travels above yams 4, 5 and 6, and then interweaves top layer yams 17-20 as shown. Yam 675 interweaves yams 11- 15, then travels above yams 6 and 7, contours below yam 8, and travels above yams 9 and 10 to complete the repeat pattern. The binder pairs 108 and 670 may be used within fabric 680 interspersed with weft yams such as those shown in FIG. 2, or with those shown in FIG. 6, to form the composite fabric 680.

Referring now to FIG.19, another binder pair, 730, in accordance with the invention is illustrated in a cross-sectional view, which forms a part of a composite fabric 700. Binder yams 710 and 720 together comprise binder pair 730, which likewise binds together the yams of paper side layer LI and wear (machine) side layer L2. Binder pair 730 can also be considered to provide a combination of the double knuckle structure of the binder 30 described above and the DCP binders also described above. The shown pattern of binder pair 730 can be a repeat pattern which repeats in the CD direction. Yam 710 forms a double knuckle DK around yams 3 to 5, and this double knuckle affords the advantages mentioned earlier. Yam 720 also forms a double knuckle DK, around warp yarns 8 and 10. Additionally, the co-location of binder yams 710 and 720 at locations above warp yams 11 and 17, for example, renders the binder pair a DCP-type binder with the attendant advantages. Note that yam 720 drops sharply from above warp yam 17 to below warp yam 8, which , results in a further minimization of the internal float of that binder yam. As in the case of binder pair 630, binder pair 730 can be implemented in a composite fabric interspersed with other binders, such as with binder pair 30 of FIG. 1 (or 17B), or any of those shown in FIGS. 11 through 18. Alternatively, binder pair 730 can be utilized as the sole binder type of fabric 700. As in the cases above, the binder pair of FIG. 19 is employed interspersed with non-binder weft yams (not shown) in fabric 700, such as those depicted in FIG. 2 or FIG. 6.

It is further noted that as a further variation to the embodiments described hereinabove, a number of the binder pairs within a fabric may be woven such that the two yams within such pairs are arranged in the same side by side (or straight) manner for all such binder pairs. Additionally, a number of the binder pairs within the fabric may be woven such that the two yams within such pairs are arranged in alternating or reverse side by side manner. As an example, in the above-described fabrics having SSB binder pairs, the SSB binder pairs may be arranged so as to be straight or reversed. Furthermore, although embodiments of the present invention have been described as having a binding pair consists of CD yams which pass over one or two MD yams on an outer surface of the paper side layer, the present invention is not so limited. That is, other arrangements may also be utilized. For example, there may be CD yams which pass over more than two MD yams on an outer surface of the paper side layer within a repeat pattern. As another example, the binder pair may include two MD yams which pass over one or more same CD ya s within a repeat pattern. As still another example, the binder ya s may pass over one or more same CD (or MD) yams on an outer surface of the machine side layer within a repeat pattern. Additionally, although the present invention has been described as usable for the papermaking process, the present invention is not so limited. That is, the present fabric may be utilized for other uses. The fabric according to the present invention may comprise monofilament yams. The CD yams may be polyester monofilament and/or some may be polyester or polyamide. The CD and MD yams may have a circular cross-sectional shape with one or more different diameters. Further, in addition to a circular cross-sectional shape, one or more of the yams may have other cross-sectional shapes such as a rectangular cross-sectional shape, elliptical or another non-round cross-sectional shape.

It will be understood that the embodiments described above are merely exemplary and that one skilled in the art can make many variations to the disclosed embodiments without departing from the scope and sprit of the invention as defined by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A fabric comprising: a first layer having machine direction (MD) yams and cross-direction (CD) yams interwoven therewith; a second layer having machine direction (MD) yams and cross- direction (CD) yams interwoven therewith; and a plurality of pairs of first type of binder yams for binding the first layer and the second layer together which are interwoven therewith so as to be (i) an integral part of the first layer and contribute to a structure thereof, and (ii) a non-integral part of the second layer and not contribute to a structure thereof, each first type pair having a first binder yam and a second binder yam; wherein during a repeat pattern the first binder yam of a first type pair is integrally woven with the yams of the first layer and passes over outer surfaces of two non-consecutive yams in the second layer.

2. The fabric according to claim 1, wherein the fabric is usable in at least one of a forming, pressing, and drying operation of a papermaking process.

3. The fabric according to claim 2, wherein the first layer is a paper side layer and the second layer is a machine side layer and wherein the first binder yam passes over the outer surfaces of two non-consecutive yams in the machine side layer.

4. The fabric according to claim 3, wherein the two non-consecutive yams have only one yam in the machine side layer therebetween in which the first binder yam does not pass over the outer surface thereof.

5. The fabric according to claim 3, wherein during the repeat pattern the second binder yam of the first type pair is integrally woven with the ya s of the first or paper side layer and passes over outer surfaces of two non- consecutive yams in the second or machine side layer.

6. The fabric according to claim 5, wherein the first and second binder yams of the first type pair together form a plain weave pattern on the top layer.

7. The fabric according to claim 2, wherein the first and second binder yarns are arranged so as to be substantially parallel to the CD yams.

8. The fabric according to claim 2, wherein the first and second binder yams are arranged so as to be substantially parallel to the MD ya s.

9. The fabric according to claim 2, wherein at least some of the MD and CD yams are monofilament yams.

10. The fabric according to claim 2, wherein at least some of the MD yams are one of polyamide yams or polyester yams.

11. The fabric according to claim 2, wherein at least some of the CD yams are one of polyamide yarns or polyester yams.

12. The fabric according to claim 2, wherein at least some of the

MD yams and CD ya s have one of a circular cross-sectional shape, a rectangular cross-sectional shape and a non-round cross-sectional shape.

13. The fabric according to claim 2, further comprising a plurality of pairs of second type of binder yarns each having a first binder yam and a second binder yam for binding the first layer and the second layer together, and wherein said first and second binder yams of at least one second type pair are interwoven with said first and second layers so as to pass over at least one common yam on an outer surface of one of the first layer and the second layer.

14. The fabric according to claim 13, wherein the first layer is a paper side layer and wherein said first binder yam and said second binder yam of said at least one second type pair pass over two common yams on the outer surface of said paper side layer within the repeat pattern.

15. The fabric according to claim 13, wherein the pairs of the first type of binder yams and the pairs of the second type of binder yams are arranged in an alternate manner such that a pair of a respective one of the first type of binder ya s is located between two pairs of the second type of binder yams and a pair of a respective one of the second type of binder yams is located between two pairs of the first type of binder yams.

16. The fabric according to claim 15, wherein each of a number of the pairs of the first and second type of binder yams are respectively located between two CD yarns such that a pair of the first type of binder ya s is located between two respective CD ya s one of which is located adjacent to a pair of the second type of binder yams, which is located adjacent to another CD yam, which is located adjacent to another pair of the first type of binder yams, and so forth.

17. The fabric according to claim 2, wherein said first and second binder yams of at least one first type pair are interwoven with said first and second layers so as to pass over at least one common yam on an outer surface of one of the first layer and the second layer during the repeat pattern.

18. The fabric according to claim 17, wherein the first layer is a paper side layer and wherein said first binder yarn and said second binder yam of said at least one first type pair pass over two common yams on the outer surface of said paper side layer within the repeat pattern.

19. The fabric according to claim 2, wherein a pair of the first type binder yams is effectively a CD yam in the first layer and wherein the fabric has a shute ratio of 3: 1 in which the shute ratio is a ratio of the number of the CD yams and the effective CD yam in the first layer to the number of CD yams in the second layer.

20. A fabric for use in fabricating paper, said fabric comprising: a first layer having machine direction (MD) yams and cross-direction

(CD) yams interwoven therewith; a second layer having machine direction (MD) yams and cross- direction (CD) yarns interwoven therewith; and a plurality of binder ya s for binding the first layer and the second layer together which are interwoven therewith so as to be (i) an integral part of the first layer and contribute to a structure thereof, and (ii) a non-integral part of the second layer and not contribute to a structure thereof; wherein at least one of the binder yams is integrally woven with the yams of the first fabric layer and passes over outer surfaces of two non- consecutive yams in the second layer during a repeat pattern.

21. The fabric according to claim 20, wherein the first layer is a paper side layer and the second layer is a machine side layer, and wherein the at least one binder yam passes over the outer surfaces of two non-consecutive yams in the second or machine side layer during the repeat pattern.

22. The fabric according to claim 21, wherein the two non-consecutive yams have only one yam in the machine layer therebetween in which the at least one binder ya does not pass over the outer surface thereof.

23. The fabric according to claim 20, wherein two binder yams are interwoven with said first and second layers so as to pass over at least one common yam on an outer surface of one of the first layer and the second layer during the repeat pattern.

24. The fabric according to claim 23, wherein the first layer is a paper side layer and wherein said two binder yams pass over two common yams on the outer surface of said paper side layer within the repeat pattern.

25. A fabric for use in fabricating paper, said fabric comprising: a first layer having machine direction (MD) ya s and cross-direction (CD) yams interwoven therewith; a second layer having machine direction (MD) yams and cross- direction (CD) yams interwoven therewith; and a plurality of pairs of binder yams for binding the first layer and the second layer together which are interwoven therewith so as to be (i) an integral part of the first layer and contribute to a structure thereof, and (ii) a non-integral part of the second layer and not contribute to a structure thereof, each pair having a first binder yam and a second binder yam; wherein the first binder yam of a pair passes in-between only two consecutive first layer yams and two consecutive second layer yams at a given location within a repeat pattern, and wherein the second binder yam of the pair passes in-between only one first layer yam and one second layer yam at a given location within the repeat pattern.

26. The fabric according to claim 25, wherein the first and second binder yams of a pair cross one another while passing in-between the top and bottom layer yams.

27. The fabric according to claim 26, wherein the first layer is a paper side layer and the second layer is a machine side layer.