US3885603A

US3885603A - Papermaking fabric

Info

Publication number: US3885603A
Application number: US417872A
Authority: US
Inventors: Philip H Slaughter
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-11-21
Filing date: 1973-11-21
Publication date: 1975-05-27
Anticipated expiration: 1992-05-27
Also published as: JPS5088307A; FR2251645A1; JPS5942116B2; NL187363B; AU7561074A; FR2251645B1; NO744168L; FI335474A; GB1492277A; NL187363C; BR7409778A; CA1027791A; SE425511B; NL7415121A; SE7414598L

Abstract

A multi-ply woven fabric especially for use as a Fourdrinier forming belt and so constructed that it has a relatively long useful life. The surface area of the fabric is at least about nine percent open, and the fabric includes at least two woven plies with the top or face ply having a considerably greater number of yarns per square inch thereof than the bottom or backing ply, and wherein the yarns in the bottom ply are substantially larger than and have a substantially greater aggregate cross-sectional area than the yarns in the top ply.

Description

United States Patent [1 1 Slaughter 1 PAPERMAKING FABRIC [75] Inventor: Philip H. Slaughter, Charlotte, NC.

[73] Assignees: Evans S. Creech; Jimmie O.

I-Iulchins; John W. Whitley, all of Charlotte, NC. part interest to each [22] Filed: Nov. 21, 1973 [21] Appl. No.: 417,872

[52] US. Cl. 139/425 A; l62/D1G. l [51] Int. Cl. D03d 15/00; D03d 15/02; D2lf1/1O [58] Field of Search 139/425 A, 425 R, 420 R, 139/383 A, 408-415; 162/348, 349, DIG. l;

[56] References Cited UNITED STATES PATENTS 1,879,243 9/1932 Hoffacker 139/415 2,157,082 5/1939 Milnes 130/383 A 2,742,059 4/1956 Watts 139/409 2,934,097 4/1960 Hindle et a1. 139/383 A 2,936,796 5/1960 Hindle et a1. 1. 139/383 A 2,949,134 8/1960 Hindle et a1. 139/383 A 3,127,308 3/1964 Justus et al. 139/425 A [451 May 27, 1975 3,222,246 12/1965 Lee 162/349 3,322,617 5/1967 Osborne 162/349 X 3,325,909 6/1967 Clark 1. 74/239 FOREIGN PATENTS OR APPLICATIONS 22,813 3/1962 Germany 162/D1G1 1 47-44,444 11/1972 Japan 4 .1 162/D1G. 1 297,739 4/1971 U.S.S,R l62/DIG. 1

Primary Examinerlames Kee Chi Attorney, Agent, or Firm-Parrott, Bell, Seltzer, Park & Gibson [57] ABSTRACT A multi-ply woven fabric especially for use as a Fourdrinier forming belt and so constructed that it has a relatively long useful life. The surface area of the fabric is at least about nine percent open, and the fabric includes at least two woven plies with the top or face ply having a considerably greater number of yarns per square inch thereof than the bottom or backing ply, and wherein the yarns in the bottom ply are substantially larger than and have a substantially greater aggregate cross-sectional area than the yarns in the top 13 Claims, 6 Drawing Figures PAPERMAKING FABRIC This application is an improvement of my copending application Ser. No. 4l7,873, filed concurrently herewith and entitled WOVEN FOURDRINIER FABRIC.

This invention relates to an improved multi-ply woven fabric especially for use in the construction of endless belts, commonly known as Fourdrinier forming belts, employed in the manufacture of paper and comparable fibrous materials.

It is well known in the papermaking industry that paper is produced by flowing a slurry of pulp or cellulosic fibers and/or other paper components mixed with water and/or other liquid onto a moving endless beit commonly known as a Fourdrinier forming belt. Fourdrinier forming belts are necessarily of substantial length and are porous so that a major portion of the liq uid is removed from the slurry by drainage. After most of the liquid has been removed, the thus formed paper web is transferred to a so-called paperrnakers drier felt which conveys the paper web through the nips of heated cylinders to extract the residual moisture from the paper web.

Papermakers drier felts are generally formed of a very coarse, compactly woven fabric. Fourdrinier forming belts, on the other hand, are quite distinct from drier felts in that at least the fact thereof must be of a fine mesh weave of relatively small strands or yarns with the mesh thereof being of such size and count as to provide at least about nine percent open area in the belt to permit ready drainage therethrough of liquid from a slurry while providing a satisfactory supporting surface for obtaining the desired quality paper product. Fourdrinier forming belts may be woven from metallic, natural and/or synthetic warp and weft yarns or strands, and it is necessary that such belts are of high tensile strength so as to be placed under substantial tension, and they also must be highly stable both widthwise and lengthwise of the belt. In other words, it is highly desirable that the belt is so constructed that it will be subject to very little, if any, stretch or elongation andlor contraction in normal use and so that the strands or yarns thereof will not shift excessively relative to each other. However, Fourdrinier forming belts have been so constructed heretofore as to have an undesirable relatively short useful life because of the flexing, relatively rapid abrasion and consequent fracture of the surfaces of those portions of the strands of the belt which engage and necessarily creep on the supporting rolls and other supporting surfaces of a papermaking machine. Such portions of the strands in the Fourdrinier forming belt are generally known as warp knuckles" and/or shute knuckles." Since Fourdrinier forming belts generally have an overall length of up to about I40 feet, not only are they quite expensive to manufacture, but considerable expense and downtime is involved in replacing an excessively worn or fractured Fourdrinier forming belt with a new one.

It is therefore an object of this invention to provide an improved woven fabric for use as a Fourdrinier forming belt and which comprises a top or face ply of relatively small strands or yarns woven in the desired fine mesh having at least about 9 percent open area and which fabric also comprises a bottom or backing ply which also has at least about 9 percent open area and whose warp yarns, at least, are of much greater size than the yarns in the top ply, with the aggregate crosssectional area of the warp yarns in the bottom ply also LII being much greater than that of the warp yarns in the top ply, thus providing a greater volume of strand material which must be worn away before the fabric will rupture, and thereby greatly extending the useful life of a Fourdrinier forming belt formed therefrom.

It is a more specific object of this invention to provide a multi-ply woven fabric of the type last described wherein not only the warp yarns in the bottom ply of the fabric are of much greater size than the yarns in the top ply, but the weft yarns also are larger in the bottom ply than in the top ply, and the top ply also has a greater number of warp yarns and weft yarns therein than there are in the bottom ply per square inch of the fabric, at least in the major or formation" area thereof; i.e., the area of the fabric upon which the slurry is deposited.

Some of the objects and advantages of the invention having been stated, others will appear as the description proceeds when taken in connection with the accompanying drawings, in which FIG. 1 is a somewhat schematic and partially exploded longitudinal or warpwise sectional view through one embodiment of the improved multi-ply woven fab ric;

FIG. 2 is a fragmentary transverse or weftwise sectional view taken substantially along line 2-2 in FIG.

FIG. 3 is a view similar to FIGv 1 showing a second embodiment of the multi-ply woven fabric including reinforcing stuffer warp yarns extending longitudinally between top and bottom plies of the fabric;

FIG. 4 is a fragmentary transverse or weftwise sectional view taken substantially along line 4-4 in FIG. 3;

FIG. 5 is a view similar to FIG. 1 showing a third embodiment of the multi-ply woven fabric wherein an intermediate woven ply is positioned between the top and bottom plies thereof; and

FIG. 6 is a schematic transverse or weftwise sectional view taken substantially along line 6-6 in FIG. 5.

Several embodiments of the improved multi-ply Fourdrinier forming belt fabric of this invention are illustrated in the accompanying drawings, all of such fabrics preferably being woven in endless form. Generally, all of the embodiments of the fabric are characterized by having interconnected plies or layers of a mesh weave with the size and number of strands or yarns per square inch in each ply being such that at least about 9 percent of the fabric is open and so that water and/or other liquid will readily flow through the fabric as such water and/or other liquid is draining from a slurry being deposited on the fabric. Also, the bottom ply of each embodiment of the fabric is woven of relatively large strands or yarns as compared to the overlying or top ply to enhance the useful life of the Fourdrinier forming belt formed therefrom, as will be later described.

Referring more specifically to the drawings, and especially to FIGS. I and 2, there will be observed the first embodiment of the improved multi-ply fabric especially constructed for use as a Fourdrinier forming belt. As shown, the fabric is broadly designated at 10 and comprises a top, outer or face ply or layer 1] and a bottom, or inner or backing ply or layer 12. The top ply II is prefeably of a plain, relatively fine mesh weave having an open area of about 9 percent and includes relatively small warp yarns l3 interwoven with relatively small weft yarns 14. Bottom ply 12 is of substantially heavier construction than top ply 11 and is woven of relatively large warp yarns l5 and relatively large weft yarns 16. As indicated above the fabric is of mesh construction so that water or other liquid in a slurry will readily drain perpendicularly through the fabric.

The top ply 11 has a substantially greater number of warp yarns 13 therein than there are warp yarns in the bottom ply 12 per square inch of the fabric 10. Also, top ply 11 has a greater number of weft yarns 14 therein than there are weft yarns 16 in bottom ply 12 per square inch of the fabric 10, at least in the major or formation" area thereof. As shown in FIGS. 1 and 2, and as is preferred, top ply 11 has about twice as many warp yarns 13 therein as there are warp yarns 15 in bottom ply l2, and top ply 11 also has about twice as many weft yarns 14 therein as there are weft yarns 16 in bottom ply 12.

As heretofore indicated, the warp yarns 1S and weft yarns 16 in the bottom ply 12 of fabric 10 are relatively large as compared to the warp yarns 13 and weft yarns 14 of the top ply 11, and it is preferred that the crosssectional area of the individual warp yarns 15 and the individual weft yarns 16 in the bottom ply 12 is about four times greater than the cross-sectional area of each of the warp yarns l3 and weft yarns 14 in top ply 11. Thus, the aggregate cross-sectional area of at least the warp yarns 15 in bottom ply 12 is substantially greater than, and preferably, at least about twice that of, the aggregate cross-sectional area of the warp yarns 13 on top ply 11 of fabric 10.

As indicated above, top ply 11 preferably is woven from relatively small yarns and is of a relatively fine mesh weave in order to properly receive a slurry of water and pulp thereon and to produce a paper material of the desired quality. On the other hand, by providing the relatively heavy yarns and substantially lesser number of yarns in the bottom ply 12 of fabric 10, not only do the relatively heavy yarns provide a mesh weave having substantially greater or thicker wearing surfaces thereon than the necessarily relatively small yarns in top ply 11 to thereby increase the useful life of the fabric 10, but the heavy warp yarns 15 also have more elongate or blunt warp knuckles on those portions thereof which pass beneath and in engagement with the weft yarns 16 in the bottom ply 12 of fabric 10, thus tending to reduce the abrasive action between the lower surface of the backing or bottom ply 12 and any rolls or other supporting surfaces over which a Fourdrinier forming belt made from fabric 10 must pass in the formation of paper thereon. Thus, the useful life of a Fourdrinier forming belt made from the fabric 10 of FIGS. 1 and 2 would be much greater than that of conventional single-ply Fourdrinier forming belts having a relatively fine mesh weave with both the upper and lower faces being formed from substantially the same size, relatively small yarns.

It is important to note that the top and bottom plies ll, 12 of fabric 10 are practically independent of each other with the exception of a plurality of relatively fine interlacing binder warp yarns 17 which extend warpwise of fabric 10 but are spaced weftwise apart from each other, Thus, in a Fourdrinier forming belt made from fabric 10, the top and

bottom plies

11, 12 may shift or yield relative to each other as successive portions of such belt are moving in engagement with the cylindrical surfaces of supporting rolls of a papermaking machine, thereby reducing the abrasive action of bottom ply 12 against such surfaces.

It is preferred that there are about one-eighth to onehalf as many binder warp yarns 17 in fabric 10 as there are warp yarns 13 is top ply 11 thereof. Also, the binder warp yarns 17 may be somewhat smaller than the top ply yarns 13, 14 so that the binder warp yarns will not form undesirable gaps between the adjacent top ply warp yarns l3 straddling the binder warp yarns 17. As preferred, the binder warp yarns 17 are looped beneath all of the weft yarns 16 in bottom ply 12 of fabric 10, but the binder warp yarns 17 are looped over only the alternate weft yarns 14 in top ply 1] of fabric 10. The plain mesh weave construction of each ply 11, I2 is shown by way of example only, it being understood that the fabric may be embodied in other suitable weave constructions, such as a twill or semi-twill weave. for example. In any event, the fine mesh top ply l1, and thus the bottom ply 12, must have an open area throughout the same of at least about 9 percent with the openings or interstices through each ply being substantially uniformly distributed throughout the same.

Although only a relatively small portion of fabric 10 is shown in FIGS. 1 and 2, it is well known that Fourdrinier forming belt fabrics are generally woven in endless form with the weft yarns 14, 16 in the two plies ll, 12 being continuous and extending in a helical manner from one edge of the belt formed therefrom to the other and throughout the upper and lower reaches of the Fourdrinier forming belt made from such fabric. Of course. the warp yarns extend transversely across such a Fourdrinier forming belt. Accordingly, since the relatively large weft yarns 16 might otherwise cross over or outside of the smaller weft yarns 14 at what normally would be the selvage of the fabric during weaving, the endless fabric may be woven with the relatively small weft yarns 14 located inside of the tubular fabric and with the larger weft yarns 16, which are lesser in number than the small weft yarns 14, being located outside of the fabric. Of course, after cutting each warpwise length from the fabric, as woven, to form a Fourdriniere forming belt of the desired width, the cut length of fabric would be obverted prior to being installed on a Fourdrinier papermaking machine so as to present the finer mesh surface of the fabric on the outside of the belt for receiving the slurry thereon.

It is important to note that, by weaving the fabric 10 in endless form to form an endless belt thereof, as indicated above, the weft yarns 14, 16 are substantially straight throughout the length of the respective endless plies ll, 12, thereby greatly enhancing the lengthwise stability of the fabric. Such stability may be further improved by heat-setting the fabric 10 if it is formed of synthetic yarns, as preferred. Of course, the warp yarns 13, 15 of the respective plies 11, 12 extend widthwise of such endless fabric and thus curve over and under the respective substantially straight weft yarns 14, 16 as shown in FIG. 1. Thus, the warp yarns 13, 15 are formed with knuckles which constitute wearing surfaces on the outer or distal surfaces of the plies l1, 12.

In order to provide a fabric which, when formed into a Fourdrinier forming belt, will have further enhanced stability in the widthwise direction of the belt; i.e., in the warpwise direction of the fabric, a second embodiment 10a of the fabric is shown in FIGS. 3 and 4 provided with stuffer warp yarns 20 throughout the length of the woven fabric. The second embodiment of the fabric includes top and bottom layers or plies I1, 12 which may be identical to the plies ll, 12 of fabric I0. Thus, all other components of fabric a will bear the same reference characters as are applied to like components shown in FIGS. 1 and 2 to avoid repetitive description. It will be noted that the stuffer warp yarns 20 extend warpwise and in a relatively straight condition in FIGS. 3 and 4. The stuffer warp yarns 20 may be made from any suitable pliable material which may be of the same or of a different type of material from that of the various yarns l3, l4, l5, 16, 17.

The stuffer warp yarns 20 preferably are somewhat larger than warp and weft yarns l3, 14 in top ply 13 of fabric 10a. Any desired number of stuffer warp yarns may be provided. As shown in FIG. 4, there are about twice as many warp yarns 13 in top ply 11 as there are stuffer warp yarns 20 between the plies, for example. It is apparent that, by providing stuffer warp yarns 20 in fabric 100, enhanced warpwise stability is obtained and, consequently, a Fourdrinier forming belt made from fabric 10a would have enhanced widthwise stability.

In FIGS. 5 and 6 a third embodiment of the fabric is shown which is broadly designated at 10b and includes three layers or plies, namely, atop ply 11, an intermediate ply 12 and a bottom ply 22. The top and

intermediate plies

11, 12 of the fabric 10b may be identical to the top and bottom plies 11, 12, respectively, of the fabric 10 shown in FIGS. 1 and 2. Accordingly the various components of the top and

intermediate plies

11, 12 of fabric 10!) will bear the same reference characters as are applied to like components of plies ll, 12 shown in FIGS. 1 and 2, where applicable, to avoid repetitive description. The top and

intermediate plies

11, 12 of fabric 10b are interconnected by binder warp yarns 17 in essentially the same manner as that in which binder warp yarns l7 interconnect the top and bottom plies ll, 12 of the fabric 10 in FIGS. 1 and 2.

The bottom ply 22 of the fabric 10b shown in FIGS. 5 and 6 includes warp yarns 25 interwoven with weft yarns 26, but the warp yarns 25 and weft yarns 26 in bottom ply 22 of fabric 10b are substantially larger than the respective warp yarns and weft yarns 16 in the intermediate ply 12 of fabric 10b. Additionally, intermediate ply ]2 of fabric 10b has a substantially greater number of warp yarns and weft yarns therein than that present in bottom ply 22.

By way of example, there are shown in FIG. 5 twice as many warp yarns and weft yarns 15, 16 in the intermediate ply 12 of fabric 10b as there are respective warp yarns 25 and weft yarns 26 in the bottom ply 22. It is preferred that the warp yarns 25 and weft yarns 26 of bottom ply 22 of fabric 10b are approximately four times the size of the respective warp yarns l5 and weft yarns l6 ofthe intermediate ply 12 in fabric 10b. In any event, each of the three plies 11, I2, 22 of fabric 10b (FIGS. 5 and 6) is in the form of a mesh weave having at least about 9 percent of its surface area open for the drainage of liquid therethrough when in use.

A plurality of binder warp yarns 27, preferably of about the same size as binder warp yarns 17, are provided for interconnecting the intermediate and bottom plies 12, 22 of fabric 10h. In this instance, binder warp yarns 27 are shown extending beneath all of the weft yarns 26 of bottom ply 22, but they only extend over alternate weft yarns 16 in the intermediate ply 12 of fabric 10!). If desired, binder warp yarns 17 might be omitted in fabric 10b. However, the upper bights of binder warp yarns 27 then would be looped over spaced top ply weft yarns 14 of fabric 10b to bind all three plies 11, I2, 22 together. In other respects, the third embodiment 10b of the fabric may be of substantially the same construction as the first and second embodiments of the fabric indicated at 10 and 100. Therefore. a further description of the fabric 10!) is deemed unnecessary.

While it is preferred that each of the three embodi ments of the fabric disclosed herein is woven from synthetic yarns, it is to be understood that the yarns may be in the form of metal strands, thay may be in the form of metal strands coated with a plastic material, they may be in the form of continuous multifilaments or monofllaments, they may be formed from yarns of natural or man-made staple fibers or they may be of any suitable combination of filaments and/0r fibers of different types. In the event that metal or plastic-coated metal yarns are present in any of the fabrics 10, 10a. 10b, it is preferred that the top ply ll of each such fabric is woven of synthetic continuous-filament or staplefiber yarns, since synthetic yarns are generally less brittle than metal yarns, and synthetic yarns generally provide a more durable and smoother surface for receiving a slurry of pulp and water thereon than is the case with metal yarns.

As heretofore indicated, the yarns 13, 14 in the top ply 11 of each fabric 10, 10a, 10b are relatively small size yarns and preferably do not exceed several hundred denier in size. Thus, for example, if the yarns 13, 14 are synthetic yarns, each of them may be of about 100 to 400 denier nylon, acrylic, polypropylene or other synthetic strand material. Also, if synthetic yarns are used, it is preferred that they are continuousfilament yarns since they would normally be of greater tensile strength than staple fiber synthetic yarns. Of course, the yarns l5, 16 in the bottom ply 12 of fabrics 10, 10a and in the intermediate ply 12 of fabric 10b should be at least about four times the size of the yarns l3, 14. Further, if the yarns 15, 16 are synthetic; e.g., nylon, acrylic, polypropylene or other synthetic strand material, each of them may be in the range of about 400 to L600 denier. The yarns 25, 26 in bottom ply 22 of fabric 10b (FIGS. 5 and 6) may be about four times the size of the yarns 15, 16 in ply 12 of fabric 10b.

It is apparent that wire strands and/or staple-fiber yarns used in place of any of the synthetic yarns 13-15, 25, 26 may be of sizes comparable with the synthetic yarn sizes mentioned above.

Non-limiting examples illustrative of many different fabrics which may be constructed in accordance with this invention will now be given. A two-ply fabric woven in accordance with the fabric 10 of FIGS. 1 and 2 has a top ply 1] whose warp yarns 13 are each approximately 210 denier polyester plied yarns, with three plies of denier multifilament polyester strands forming each warp yarn 13. About of such wary yarns per inch are interwoven with about 48 polyester weft yarns per inch, each weft yarn 14 being approximately 300 denier and formed of three plies of I00 denier multifilament polyester strands. A bottom ply 12 of the illustrative fabric 10 of FIGS. 1 and 2 is formed of about 40 warp yarns per inch interwoven with about 24 weft yarns per inch. Each of the warp yarns 15 in the bottom ply 12 of the fabric 10 is formed of three plies of 300 denier multifilament polyester strands so that each warp yarn 15 has a total denier of 900. The weft yarns 16 in the bottom ply 12 of the illustrative fabric are each formed of three plies of 440 denier multifl ament strands so that each weft yarn 16 has a total de nier of approximately L320. The binder warp yarns 17 are approximately l02 denier multifilament polyester yarns and are alternately arranged with respect to the warp yarns in the bottom ply 12. Thus, 40 binder warp yarns are provided per inch of the fabric 10.

As heretofore indicated, in weaving a typical fabric 10a according to the second embodiment of FIGS. 3 and 4, the stuffer warp yarns 20 preferably are somewhat larger than the warp and weft yarns l3, 14 in the top layer 10 and there are about twice as many warp yarns 13 in the top ply as there are stuffer warp yarns 20 between the plies. Thus, a further illustrative example of the fabric 100 of FIGS. 3 and 4 is deemed unnec essary.

In a typical fabric woven in accordance with the fabric 10b of FIGS. 5 and 6, the top and intermediate plies l1, 12 of the fabric 10b may be constructed in the manner as described above in the example of the fabric 10, and the bottom ply 22 of fabric 10b may be formed of approximately 20 ends per inch of warp yarns 25 with each warp yarn 25 being approximately 3600 denier and being formed of three plies of 1200 denier multifilament polyester strands. In such an instance, 12 ends of weft yarns 26 would be provided per inch in the bottom ply 22 of fabric 10b, with each end of weft yarn 26 being approximately 4800 denier and preferably being formed of three plies of 1600 denier polyester strands. It is apparent that many different sizes and types of yarns may be used in forming the various embodiments of the fabric in accordance with this invention. Thus, a description of additional examples of the fabric is deemed unnecessary.

It is thus seen that l have provided a multi-ply woven fabric which is particularly useful in the construction of an endless Fourdrinier forming belt and is especially constructed to withstand flexing, high tension and abrasion incidental to paper manufacutre. It is seen further that the fabric comprises at least two interconnected plies, each of which is formed of respective interwoven warp and weft yarns with the interconnected plies including at least a top ply and a bottom ply therein. The top ply includes relatively small size warp yarns and weft yarns, and the bottom ply includes relatively large warp yarns and weft yarns as compared to the size of the warp yarns in the top ply. The top ply also has a substantially greater number of warp yarns and weft yarns therein than there are present in the bottom ply in each instance. Also, the aggregate crosssectional area of the warp yarns in the bottom ply, in each instance, is substantially greater than the aggregate crosssectional area of the warp yarns in the top ply of the fabric with the result that a substantially greater amount of yarn is present on the bottom of the fabric to be subjected to the wear and abrasion of the supporting rolls and other supporting surfaces over which a Fourdrinier forming belt must pass and thereby greatly extending the useful life of a Fourdrinier forming belt made from the fabric of the present invention as com pared to those used heretofore.

It is preferred that each of the embodiments of the fabric 10, 10a, 10b is woven in endless form, as described herein, so that the weft yarns thereof will extend lengthwise around the Fourdrinier belt formed therefrom. It is apparent, however, that each embodiment of the fabric may be woven of the desired weftwise width and in indefinite warpwise lengths, after which the fabric may be cut to the desired warpwise lengths and opposite ends thereof then may be suitably spliced together to form an endless Fourdrinier belt therefrom.

In the drawings and specification, there has been set forth, preferred embodiments of the invention, and although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation.

That which is claimes is:

l. A multi-ply woven fabric of mesh construction for use as a Fourdrinier forming belt and especially constructed to permit drainage therethrough of liquid from a slurry received thereon and to withstand flexing, high tension and abrasion incident to paper manufacture, said fabric comprising at least two plies each having an open area of at least about 9 percent and each ply being formed of respective interwoven warp and weft yarns, binder warp yarns interwoven with and interconnecting said plies, said plies including a top ply and a bottom ply, and said top ply being formed of a considerably greater number of warp yarns and weft yarns per square inch than said bottom ply with at least the warp yarns in said top ply being substantially smaller than the warp yarns in said bottom ply, and the aggregate crosssectional area of the yarns in said bottom ply being substantially greater than that of the yarns in said top ply per square inch of the fabric.

2. A multi-ply woven fabric according to claim 1, wherein said top ply includes about twice as many warp yarns therein as there are in said bottom ply.

3. A multi-ply woven fabric according to claim 1, wherein each of said binder warp yarns is interwoven back and forth between the two plies interconnected thereby and extends over spaced weft yarns only of said top ply, but extends under all of the weft yarns in said bottom ply.

4. A multi-ply woven fabric according to claim I, wherein said binder warp yarns are smaller than said warp yarns in said top ply.

5. A multi-ply woven fabric according to claim 1, wherein the warp yarns in each of said plies extend over and under all of the weft yarns in the respective ply, and wherein only said binder warp yarns extend between and interconnect the adjacent plies.

6. A multi-ply woven fabric according to claim 1, including a plurality of stuffer warp yarns positioned between said top and bottom plies of the fabric.

7. A multi-ply woven fabric according to claim 1, including an additional intermediate ply of interwoven warp and weft yarns positioned between said top and bottom plies, and interconnect binder warp yarns connecting said intermediate ply to said top and bottom plies.

8. A multi-ply woven fabric according to claim 7, wherein said binder warp yarns include upper binder warp yarns extending between and interwoven with and interconnecting said top ply and said intermediate ply, and lower binder warp yarns extending between and interwoven with and interconnecting said intermediate ply and said bottom ply.

9. A multi-ply woven fabric of mesh construction for use as a Fourdrinier forming belt and especially constructed to permit drainage therethrough of liquid from a slurry received thereon and to withstand flexing, high tension and abrasion incident to paper manufacture, said fabric comprising at least two plies each having an open area of at least about 9 percent and each ply being formed of respective interwoven warp and weft yarns, binder warp yarns interwoven with and interconnecting said plies. said plies including a top ply and a bottom ply, said top ply being formed of a considerably greater number of warp yarns and weft yarns than said bottom ply, and the size of the warp and weft yarns in the bottom ply being substantially larger than the warp and weft yarns in the top ply,

10. A multi-ply woven fabric of mesh construction for use as a Fourdrinier forming belt and especially constructed to permit drainage therethrough of liquid from a slurry received thereon and to withstand flexing, high tension and abrasion incident to paper manufacture, said fabric comprising at least two plies each formed of respective interwoven warp and weft yarns, the size and number of warp and weft yarns per square inch of each respective ply being such that at least about 9% of each ply is open area, binder warp yarns interwoven with and interconnecting said plies, said plies including a top ply and a bottom ply, said top ply being formed of relatively small warp yarns and relatively small weft yarns, said bottom ply including relatively large warp yarns compared to the warp yarns in said top ply, said top ply having about twice as many weft yarns therein as there are in said bottom ply per square inch of the fabric, said top ply also having a greater number of warp yarns therein than there are in said bottom ply, and the aggregate cross-sectional area of the warp yarns in said bottom ply being substantially greater than the aggregate cross-sectional area of the warp yarns in said top ply.

11. A multiply woven fabric of mesh construction for use as a Fourdrinier forming belt and especially constructed to permit drainage therethrough of liquid from a slurry received thereon and to withstand flexing, high tension and abrasion incident to paper manufacture, said fabric comprising a top ply, a bottom ply, and an intermediate ply between said top and bottom plies, binder warp yarns interwoven with and interconnecting all of said plies, each of said plies comprising interwoven warp and weft yarns with the size and number of warp and weft yarns per square inch of each ply being such that at least about 9 percent of each ply is open area, said top ply having about twice as many weft yarns therein as there are in said intermediate ply, said intermediate ply having about twice as many weft yarns therein as there are in said bottom ply, and the warp yarns and weft yarns of said intermediate and bottom plies being relatively large as compared to the warp yarns and weft yarns in said top ply.

12. A multi-ply woven fabric of mesh construction for use as a Fourdrinier forming belt and especially constructed to permit drainage of liquid therethrough from a slurry received thereon and to withstand flexing, high tension and abrasion incident to paper manufacture, said fabric comprising at least two plies each formed of respective interwoven warp yarns and weft yarns with the size and number of warp and weft yarns per square inch of each ply being such that at least about 9 percent of each ply is open area, binder warp yarns interwoven with and interconnecting said plies. said plies including a top ply and a bottom ply, said top ply having a substantially greater number of warp yarns and weft yarns per square inch of said fabric than the bottom ply, said yarns in said top ply being substantially smaller than the yarns in said bottom ply, said binder warp yarns being relatively small and looped over weft yarns in said top ply and beneath weft yarns in said bottom ply, and a plurality of stuffer warp yarns positioned between said top and bottom plies of said fabric.

13. A multi-ply woven fabric of mesh construction for use as a Fourdrinier forming belt and especially constructed to permit drainage therethrough of liquid from a slurry received thereon and to withstand flexing, high tension and abrasion incident to paper manufacture, said fabric comprising at least two plies each having an open area of at least about 9% and each ply being formed of respective interwoven warp and weft yarns, binder yarns interwoven with and interconnecting said plies, said plies including a top ply and a bottom ply, and said top ply being formed of a considerably greater number of warp yarns and weft yarns per square inch than said bottom ply with at least the warp yarns in said top ply being substantially smaller than the warp yarns in said bottom ply, and the aggregate crosssectional area of the yarns in said bottom ply being substantially greater than that of the yarns in said top ply per square inch of the fabric.

Claims

1. A multi-ply woven fabric of mesh construction for use as a Fourdrinier forming belt and especially constructed to permit drainage therethrough of liquid from a slurry received thereon and to withstand flexing, high tension and abrasion incident to paper manufacture, said fabric comprising at least two plies each having an open area of at least about 9 percent and each ply being formed of respective interwoven warp and weft yarns, binder warp yarns interwoven with and interconnecting said plies, said plies including a top ply and a bottom ply, and said top ply being formed of a considerably greater number of warp yarns and weft yarns per square inch than said bottom ply with at least the warp yarns in said top ply being substantially smaller than the warp yarns in said bOttom ply, and the aggregate cross-sectional area of the yarns in said bottom ply being substantially greater than that of the yarns in said top ply per square inch of the fabric.

4. A multi-ply woven fabric according to claim 1, wherein said binder warp yarns are smaller than said warp yarns in said top ply.

9. A multi-ply woven fabric of mesh construction for use as a Fourdrinier forming belt and especially constructed to permit drainage therethrough of liquid from a slurry received thereon and to withstand flexing, high tension and abrasion incident to paper manufacture, said fabric comprising at least two plies each having an open area of at least about 9 percent and each ply being formed of respective interwoven warp and weft yarns, binder warp yarns interwoven with and interconnecting said plies, said plies including a top ply and a bottom ply, said top ply being formed of a considerably greater number of warp yarns and weft yarns than said bottom ply, and the size of the warp and weft yarns in the bottom ply being substantially larger than the warp and weft yarns in the top ply.

11. A multi-ply woven fabric of mesh construction for use as a Fourdrinier forming belt and especially constructed to permit drainage therethrough of liquid from a slurry received thereon and to withstand flexing, high tension and abrasion incident to paper manufacture, said fabric comprising a top ply, a bottom ply, and an intermediate ply between said top and bottom plies, binder warp yarns interwoven with and interconnecting all of said plies, each of said plies comprising interwoven warp and weft yarns with the size and number of warp and weft yarns per square inch of each ply being such that at least about 9 percent of each ply is open area, said top ply having about twice as many weft yarns therein as there are in said intermediate ply, said intermediate ply having about twice as many weft yarns therein as there are in said bottom ply, and the warp yarns and weft yarns of said intermediate and bottom plies being relatively large as compared to the warp yarns and weft yarns in said top ply.

12. A multi-ply woven fabric of mesh construction for use as a Fourdrinier forming belt and especially constructed to permit drainage of liquid therethrough from a slurry received thereon and to withstand flexing, high tension and abrasion incident to paper manufacture, said fabric comprising at least two plies each formed of respective interwoven warp yarns and weft yarns with the size and number of warp and weft yarns per square inch of each ply being such that at least about 9 percent of each ply is open area, binder warp yarns interwoven with and interconnecting said plies, said plies including a top ply and a bottom ply, said top ply having a substantially greater number of warp yarns and weft yarns per square inch of said fabric than the bottom ply, said yarns in said top ply being substantially smaller than the yarns in said bottom ply, said binder warp yarns being relatively small and looped over weft yarns in said top ply and beneath weft yarns in said bottom ply, and a plurality of stuffer warp yarns positioned between said top and bottom plies of said fabric.

13. A multi-ply woven fabric of mesh construction for use as a Fourdrinier forming belt and especially constructed to permit drainage therethrough of liquid from a slurry received thereon and to withstand flexing, high tension and abrasion incident to paper manufacture, said fabric comprising at least two plies each having an open area of at least about 9% and each ply being formed of respective interwoven warp and weft yarns, binder yarns interwoven with and interconnecting said plies, said plies including a top ply and a bottom ply, and said top ply being formed of a considerably greater number of warp yarns and weft yarns per square inch than said bottom ply with at least the warp yarns in said top ply being substantially smaller than the warp yarns in said bottom ply, and the aggregate cross-sectional area of the yarns in said bottom ply being substantially greater than that of the yarns in said top ply per square inch of the fabric.