CA2112124A1

CA2112124A1 - Multi-plane dewatering fabric

Info

Publication number: CA2112124A1
Application number: CA002112124A
Authority: CA
Inventors: Graham William Jackson
Original assignee: Individual
Current assignee: Jwi Ltd
Priority date: 1991-07-12
Filing date: 1991-07-12
Publication date: 1993-01-21
Also published as: EP0594617A1; JPH07500381A; FI940134A0; MX9204090A; WO1993001350A1; FI940134A

Abstract

A dewatering fabric for the press section of a paper making machine is described having improved dewatering characteristics, improved resistance to compaction, and enhanced ability to bridge cavities, such as grooves or holes, in press section rolls. The fabric includes at least two distinct layers of flattened monofilament warp yarns at a high fill factor, and at least one layer of weft yarns. Advantageously, the fabric is constructed to provide long exposed floats of one of the distinct layers of warp yarns on the paper side of the fabric. The fabric may be used alone, with a paper side batt, or with a batt on both sides.

Description

WO 93/01350 pcr/cA9l/oo247 ,!. ~ .'' ,., 1 ~ l~

~ULTI-PLANE DEW~TERING FABRIC

This invention relates to dewatering fabrics used in the press section of a papermaking machine. It is particularly concerned with a press section fabric including multiple distinct layers of nattened monofilament warp yarns confi~red to provide improved roll nip pressure unifo2Jnity, reduced paper marking, increased paper dewatering and enhanced compaction resistance.
. .
Pressure non-uniformity in a press nip can ari~e from two sources:
a) the pres~ rolls themselves, wbich may be grooved or drilled to provide void space for the water e~presfied from the web in the nip; and b) the press fabric it~elf, which, due to its woven structure (or other reasons) transmits press nip pressures unevenly. In different situations, either of these two sources may be the dominant source of non-uniformity and hence of paper marking or low dewatenng. In some cases, for example, the pattern of the grooves of the press roll can be seen clearly in the finished paper, while in other cases, the marks of the woven structure of the fabric can be seen.
Sometimes both marks are present.

The first proposal to use flattened monofilament warp yarns in a press section fabric was by Miller et al., U.S. 4,414,263. Miller et al.
advocated using ~lattened monofilament yarns with a relatively low aspect ratio in an otherwise conventional weave. Vanations on the Miller et al.
fabric which are proposed by Stanley, U.S. 4,973,512 and U.S. 5,023,132.
An improved fabric using flattened monofilament warp yarns is described by Jacks~s'W0 9V04374. In the Jackson fabric, a flattened monofilament warp yarn with a somewhat higher aspect ratio i8 used at a high fill factor, in a weave pattern which provides long exposed floats of flattened monofilament warp yarns on the paper side of the fabric. This weave construction provides a relatively flat, ~mooth, almost platform-like surface on the paper side of the fabric. This relatively flat surface transfers the wo 93/013S0 PCI /CA91/00247 2 1i21~ -2-mechanical loads imposed by the press section rolls from the press fabric to the paper web in a way that provides improved pre~sure uniformity.

The ma~mum benefit of a Jackson press section fabnc appears to be obtained in a weave design that includes a ~ingle layer of weft ya~s. In this type of fabric, the maximum float length for the flat warp yarns can be achieved, thereby imparting the masimum smoothness and pressure unifo~nity to the fabric.
.
However, it has now been found that a fabric containing a single layer of weft yams as described by Jackson has certain disadvantage3. In particular, it seems not to be entirely suitable for coDfigurations in which at least one of the pres~ rolls has cavities, ~uch as grooves or holes in its ~ce. It appears that such a thin fabric when u~ed in a press felt i .

unable to bndge these roll cavities adequately, and pressure non-uniformity on the paper web results. If a double weft yarn layer fabnc design is used, as IS described by Jackson, in order to bridge the press roll cavities better, ~the amount of flattened monofilament wa2p yarn~ which can be esposed on the paper side of the fabnc is not as high as can be e~posed for a single weft yarn fabric design. This is because the flattened monofilament warp yarn~ follow a generally diagonal path within the fabric when they interweave with t~e bottom weft yarns. This limits the length of float t~at can be exposed on the paper side of the fabric.

Thus'there has been found to be a balance between enhanced pressure uniformity on the paper side of the fabric, and press roll cavity bridging on the press roll side of the fabric. If a double wef~ ya~ layer fabric i8 used there iB the filrther disadvantage that the peak pressure in the roll nip is not as bigh as is obtained with a single layer fabric, and WO 93/01350 PCT/CA91~00247 2 ~ r ~ 1 2 ;~

therefore a douUe weflG yarn layer fabric will dewater the sheet of paper less.

This invention seeks to overcome these problems and to provide an improved fabric of the type descri~ed by Jackson which provides better roll cavity bridgiIIg characteristics and better pressure unifo~ty. Further, this invention also seeks to enhance the compaction resi~tance of the fa~ric.
Additionally,~ this invention seek~ to prov de a fabric in which these Dnpro~rements can be realised without losing the ability to have long e~posed floats of flattened monofilament warp yarns on the paper side of the fabric.

These improvements are obtained by incorporating into the fabric at least two distinct layers of flattened monofilament wa~p yarns, and at least one layer of weft yarns. One layer of flattened monofilament warp yarn6 provides the long esposed floats generally on one side of the fabric.
Further, if a double weft yarn layer construction is used, the other warp n layer(s) can be utilised to maintain good separation between the upper and lower wef~ yarn layers (that is, the weft yarn layer~ adjacent the paper side and the press roll side of the fabric, respectively) without having to .

dimi~ish in any way- the amount of long esposed flattened monofilament warp yarn floats on the paper side of the fabric. The separation thereby obtained between two weft ya~n layers enhances fabric compaction resistance and available void volume.

We have found that fabrics woven according to this invention reduce marking by both the press rolls and-the press fabric, and the exact oonfi~ration of the two layers of ~at warps can be adjusted for these different circumstances. If the press roll grooves are 1he main source of non-uniformity, it may be beneficial to locate the long floats close to the roll surface. In other cases, the long float~ may be beneficially located nearest the paper side surface of the fabric.

In the fabrics of this invention, the term "warp yarn" is used to designate the warp on the weaving loom, that i8 the set of yarns that travel from the warp beam through the heddles of the loom, and wbich form the shed through whi~h the wePc yarn i~ passed. If a fabric of this invention is woven as an endless loop, the flattened monofilament waIps lie in the icross-machine idirection of the paper making mai~hine. It i8 known to weave an endless loop ~ncorporating a seam, or to insert a seam later, in order to &cilitate installation in a press section. Alternatively, if a fabric of this in~rention is woven as a "flat" fabric, a~ a continuous run, and then joined into the required endless loop with a suitable seam, the flattened monofilament warps lie in the machine direc~on of the paper making macbine.

Thus, in a first broad aspect this`invention provides a woven dewatering fabric, for the press section of a papermaking machine, having a first side and a second side, one of which constitutes the paper side of the fabric, and the other of which constitutes the press roll side of the fabric, andha~inglo~gexposed floats of flattened monofilamentwarpyarns on the first ~ide of the fabric, wherein:

(i) the aspect ratio of the flattened monofilament - ' warp yarns is at least 1.5:1;
(ii) the fabric weave includes at least two distinct layers of warp yarns each including flattened monofilament warp yarns, one of whicb pro~ides the exposed first side float;

WO 93/01350 PCl/CA91/00247 (iii) the fabrîe weave further include~ at least one layer of wef~c yarn6; and (iv~ the fill factor for each of the distiIlct layer~
including flattened monofilament warp yarns i~ at lea~t 45%.

Preferably, the long exposed float~ on the first side of ~he ` ~ fabric satisfy a definition for 'float ratio' ~imilar to the one given by JacJ~on, WO 9V04374, modified to fit`t~e fabrics of this i~rention. For t;he fabrics of this invention it i8 preferred that the long espo~ed float6 on the first ~ide of the fiablic ~ati~fy a float ratio fonnula x/y, wherein:

(i) "x" represents t;he number of wef~ ya~ in a wef~
y~ layer on the first ~ide of the fabnc in a single weave patte~n repeat which are on t}-e in~ide of the: ~bric with respect to a particular flattened monofilament warp ya~, and supporting that ~varp yarn; and - (ii) "y" representfi the total num~er of we~
yams in the wef~c yarn layer on the fir~t side of the fabric in a ~ingle weave pattern repeat;

and wherein for a m~ority of the fir~t side e~zposed floats of flattened monofilam-ént warp yarns:

(iii) x i~ greater than one; and ~iY) x i8 greater tban one-half of y.

WO 93/01350 PCr~CA91/00247 2 !~ ~12~

In some application~, it i8 possible to use the fabrics of this invention in a press roll section without a porow layer, such as a needled fibrous batt, attached thereto. Conveniently, a porous layer, such as a fibrous batt, - can be attached to the paper side, or to both the paper side and the press roll side, of the fabric.

Prefernbly, the flattened monofilament wa~p yarn~ making up each of the dill~na iayers of warp yar~s are situated substantially vertically above one another in the ~Ivoven fabric.

The invention will now be discussed by way of referencs to the attached ~Ygures in which:

Figures l, 2 and 3 show a single weft yarn l~yer fabric;
Figures 4 through 11 show alternative wea~re pattern~; -Fi~res 12 and 13 show a wea ve pattern incorporating a binder tie yarn;
Figures 14, 15 and 16 show fabrics carrJnng porous layers; and Figure 17 sho~s the face of a fabnc.

In Figu~re 1 i~ shown A single we~ yarn layer fabric according to this in rention. The fabric as sho~m includes three layers of yarn~:

(i) an upper, side A, set of flattened mono-filament _, warp yarns 1, 3, 5 & 7;
(ii) a lower, side B, set of flattened monofilament warp yarns 2, 4, 6 & 8; and (iii) a ~ingle layer of weft ya~ns 1, 2, 3, 4, 6, 6, 7 & 8.

Sl~5~ iTE SHEET

WO 93/01350 PCl!CA9lJ00247 Each set of warp yarns iB woven at à fill factor of at least 45%, and preferably of about 85%. ThUB the combined fill factor for the two sets of waIp yarns iB greater than 90%, and preferably iB about 170%. This high fill factor for the nattened monofilament warp yarns provides the improved pressure unifonnity on the paper side, improved press roll cavi1 y bridgiDg on the press roll ~ide, and enhanced compaction resistance of the fabric.

Figures 2 and 3 8~0W schematically the weave pattern for the fabnc of Figure 1. In these and later figures three con~rentions are used; it can be seen that the yarns in Figure 1 are numbered to matdl Eigures 2 and 3.
First, in Figure 2 a filled-in ~quare indicates that at that point a warp yarn pas~es over a wef~ yarn. Second, Fig~are 3 represents a cross secffon based on Figure 2 aIong the line of 1 he walp yarn numbers given: thus in Figure 3 the walp yarns are numbers 1 & 2 from Figure 2, and the section in Figure 3 iB the lef~hand side of the diagram in Figure 2. Third, 'A' represents the fir~t side and 1~' the second side, of the fabric. In all of these fabrics the side A include~ the long e~cposed float~.

Certain other features of the fabrics of this in~ention can be seen in ~igure 1.

Fir~t of all, only one set of yarns, 1, 3, 5 & 7, is e~posed on the side A of the fabric. As shown, the two sets of waIp yarns are substantially one over the other: thus warp ya~n 1 is abo~e warp yarn 2, and 80 on. ThiB is largely a consequence of the fill factor used; generally, tbe higher the fill factor the better thi~ correlation will be. It can also be seen that at some points in this single weft yarn layer &bric walp yarns ~om both sets pas~
the same side of particular weft yarn: warp yarns 1 and 2 both pass o~rer the side A of weft yarn 2, and pass under the side B of weft yarn 8. Fi~ally, as shown this fabric is effectively the same on both faces, as the weave SUBSTITUTE SHEET

WO 93~01350 PCI`/CA91/00247 I 2; -8-psttern~ for the two sets of warp yarns are mirror images of each other.
This is not necessary, and the weave pattern adopted for the press roll ~ide B can be dif~erent to that of tbe paper side A.

In a fabr~c such as tbat in Figure 1 as the fabric iB the same on both faces, it does not matter which of side A and side B i8 taken as the paper ~ide of the fabric, and which i8 taken a~ tbe pre~ roll side of t}le fabric. In these Figures as noted above tbe convention i8 adopted that the first side of the fabric, which includes the long e~cposed ~loats, is identified as side A.Generally, it is preferred that side A be tbe paper side ofthe fabric, but this is not necessary. The fabrics of this invention function adequately in Bome applications when side A is the press roll side of the fabnc.
.

The warp yarn weave pattern on the side A of the fabric preferably utilizes the long exposed float concepts de~cribed by Jackson in WO
9V04374. That is, the weave pattern includes long e~ ed float~ of flatbned monoSlament warp yan~ with an aspect ratio of at least 1.5:1 on the~ side A of the fabric but not necessarily on the side B of the fabric.
These long e~cposed floats can be characterized by a "float ratio" e~cpressed by the formula x/y as defined above. There is an upper limit to the float ratio, which i8 the point at which fabric integrity becomes questionable. For a fabric similar to that ~ho~n in F'igure 1, this seems to occur at a float ratio of about 9l10. It al~o appears that if the values of s and y are both low, or if x i8 clo~e to one half of y, then the dewatenng properties of the fabric are im, paired.
.

The flcat ratio in a given f~bric need not be consta~t either along a given nattened monoSlament warp yam, or for aU of the 9attened monofilament warp yarns in a given weave. Further, not all of the e~po~ed floats offlattened monofilament warp yarll8 need have a floatratio in which SUBSTITUTE SHEET

WO 93/0135(1 PCr/CA91/002~7 12 ~
g ~c is both greater than one, and greater than one half of y, although ma~cimum benefit will be obtained if these restrictions are obse2~red. AB i8 shown in Figure 17, which ~hows only the side A of the fabric, a fabnc can be woven ~with varying float ratios. From the top downwards in Figure 17 the float ratios are 7/8, 5/8, 6/8, 418, 6/8, 3J8 and 5/8. In a similar wsy the float length can be varied along a given flattened monofilament warp yarn, to pronde in sequence a 112 unit, then a 5/6 UlIit, for e~cample. In such a case the float ratio should be determined o~er the fi~ ngth of the pattern repeat, and V2 combined with 5/6 in fact i~ 6/8.

The warp yarn wea~re pattern on the side B of the fabric i8 not BO
restricted, as i8 shown in the wea~re designs of Fi~res 4 t~ough 9. In ea~
of these, wbilst an adequate float ratio iB maintained for the set of warp yarns pro~riding the side A long e~cposed float~, the path for the other wa~
yan~s can be quite dif~erent. Figures 6 and 7 show a second fabnc in which ~he wsTp yaTn weave patterns are mirror images of each other, while in Figures 4, 6, 8 and 9 the patterns are quite dif~erent. The float ratio for ~ide A of each of these weaves ;B:
.. ~c Figure 3 7 8 7/8 Figure 5 6 8 6/8 Figure 7 5 8 5/8 Figure 9 7 8 7/8 F~om these Eigures and the den~ed float ratios it can be seen how the float ratio is calculated. In each case it ;8 ODIY the weft yar~s supporting a warp yarn which are counted. In each of these ~igures, as is indicated at X, there is a second warp yarn between the esposed float a~d a weft yarn: that wef'c yarn is taken to be supporting the warp yarn float.

SUBSTITUTE SHEET

WO 93/01350 PCr/CA91/00247 ~ I L ~ 10-The designs of ~igures 4, 5, 6 and 7 have flattened monofilament warp yaIns on both sides of the fabric providing good paper side pre~AUre uniformity and good press roll venting cavity bridging. Ln Figares 8 and 9 the design has flattened monofilament warp yarn floats on the side A of the fabric, but unlike Figures 6 and 7 the ~econd warp yarn~ are highly interlaced between each layer of wef~ yarns providing good paper side pres~ure uni4rmity and good compaction re~istance.

In the designs of Figures 4, 5, 8 and 9 (and also Figures 10 and 11, described below) the wa~p yarn sets have diffenng path length~. Designs of this type may require the use of two, or more, warp yarn beams, as is well known to those skilled in the art of weaving. The designs illustrated are- all interwoven 80 that the result is a single fabric.

Figures 10 and 11 illustrates a design using two layers of wef~ yarns, and three layers of flattened monofilament warp yarhs 1, 2 and 3. As shown, the weave pattern for wa~p yarn 1, on the side A of t~e fab ic and waIp yarn 3, on the side B of the fabric, are essentially similar, but this i8 not necessary: the pattern for wa~p yarn 3 can be different. The third layer of warp yarns, 2, iB interlaced into the wefl; yarns between the other two.
Due to the high fill factors used for each warp yarn, in the woven fabric the three warp yarns lie ~ubstantially above each other. In this fabric the float ratio is 5/6.

Figures 12 and 13 illustrate a fabric in which the two distinct layers _.. ~
of flattenedlmonofilament wa~p yarns weave separately into the two sets of weft yarns. One set of flattened monofilament warp yarns ~veaves into the gide A ~et of wefts (the even numbered ones) ant the other set of flattened monofilament warp yarns weaves into the side B set of wefts (the odd numbered ones). Again, although the weave pattems sho~vn are essentially SUBSTITUTE SHEET

WO 93/01350 PCI`/CA91/00247 2: ~ ~v 1 ~ '~

the same for each ~et of flattened monofilament warp yarns, the pattern for side B need not be the ~ame as that for side A. The float ratio is 6/6. These two layers are then joined together in the weave by the separate binder yarns Y. The~e separate binder yarns can be incorporated either in the warp yarn direction (as shown in Figure 13) or in the weft yarn direction (not shown). Generally binder yarns are small relative to the warp yarns or weft yarn~, often serving only to hold the fabric together during weaving and subsequent proces~ing, until a fiber batt layer is attached by needling thus binding the entire structure together. In some case~ the binder yarns are soluble yarns and are removed by washing after needling. In other cases where no batt or other porous layer is used the binder yarns are stronger and withstand use in the press section, to keep the two layer~ cf the fabric ~om separating.
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It is possible to we the fabrics of this invention on their own in a press sec~on. As was noted above, cases where the fabric wea~re pattern is such that the fabric is essentially the same on both faces, whether side A
or side B is the paper side of the fabric does not matter. But when an unsymmetrical weave, such a3 that in Figure 5 or Figure 9 is used the fabnc faces cease to be the same. ~ most applications it is preferred tbat side A, the fir~t side which incorporates the long e~cposed floats of flattened monofilament ~varp yarns, is taken a~ the paper ~ide of the fabric.

Alternatively, as shown in Figure 14, 15, and 16, the fabrics of this i~ventio~ ~ay also be used with porous layers attached thereto. If only one Iayer is used, generally it will be attached to the paper side of the fabric, ~uch as the layer 70 attached to side A of the fabric, or the layer 80 attached to side B of the fabric, in Figures 14 and 15. Two porous layers, aB at 70 and 80 in Figure 16 may be attached one to ea¢h side of the fabric.
Again alt~ough this seemingly makes both faces of t}le fabric the same, it SUBSTITUTE SHEE~

wo 93/0l350 Pcr/cAgl~00247 ~1 I2~ '~4 -12-is still preferred that side A with the first set long e~cposed floats iB the paper side of the fabric. Thus the single batt arrangement of Figure 14 iB
preferred rather than Fi~re 1~.
:

Typically a porous lsyer 70, 80 comprises a staple fiber batt, which i8 generally attached to the fabric by needle punching.
~ . :
~- - If a batt iB used, some thoug~t should be given to the direction in which it is laid, since it i~ known that the batt Sbers tend to be oriented substantially in the direction the batt is laid onto the base fabric. For the fabrics of this invention it i8 preferred that a batt iB laid with a high degreeof fiber orientation. There are, nevertheless, several options for the direction of orientation, relative to the direction of the long e~posed floats in side A of the fabric, regardless of whether side A i8 or i8 not the paper side of the fabric.

For a fabric with a 6ingle batt layer, the orientation can be sub~tantially parallel to, or substantially perpendicular to, the side A
e~posed floats.

For a fabric ~vith two batt layers, one on each side of the fabnc, the onentation of each batt independently can be substantially parallel to, or substantially perpendicular to, the side A esposed floats. Tbu~ there are four options: both side A and side B batts oriented in the ~ame direction, and either, parallel or perpendiculsr to the side A e~cposed floats, or the sideA and side B batt~ oriented substantially perpendicular to each other, and one of them - either side A or side B - parsllel to the long e~posed floats.

In the fabric of this invention a high ~veft ysrn fill, as ~ell as a high flattened monofilament warp yarn Sll of at least 45%, is recommended, in SUBSTITI)~E SHEET

f ~

order to minimize the space between the flattened warp yarn 8UppOI't points, such as the distsnce Z in Figure 3. The purpose of this high wePl yarn fill i8 to reduce the bending of the nattened monofilament warp yarns in a direction at right angles to their plane in the fabric under the influence of the very high pressures exerted on the fabric in the pres~. Several variables affect the weft yarn fill factor in a given fabric. Some of these are:
(a) ~ the degree of openness required in the fabnc;
(b) the thickness of the flattened monofilament .
warp ysrns;
(c) the material used for the flattened monoSlament warp yarns: a stiff material with a high elastic modulus deflect~ less than a 80ft one; and (d) the degree of softness of the weft yarns: a ~oft deforma~le weft yarn provides better support than a yarn which is hard and makes contact with the warp yarns along a ..
thin line.

In practice? it appears tbat the weft yarn spacing, a~ at Z in Figure 3, should be less than 8 times the flattened monofilament warp yarn thicknes~, and is preferably less than 5 t mes. ;~ -~

Generally pres~ fabrics are constructed ~om nylon monof~aments, with a nylon staple fiber batt, although polyester and other matenals are sometimes used. It is preferred to use nylon for this invention, but this invention is not BO limited.

WO 93/01350 PCr/CA91/00247 ~. 1 12124 The distinct warp yarn layers in t~e fabric of this invention are woven from flattened monofilament yarns. In these ~attened monofilament warp yarns, the aspect ratio, that is the ratio of wid~h to thicknes6, ~hould be at least 1.5:1. If the thickness is made too low, the filament become~ too thin and too fle~ible, and tends to transmit both knuckle markings from the fabric weave and any pattern of cavities in tbe press ro~ls to the paper. A
suitable lower limit for the thickness appears to be at about 0.1 mm. If tbe aspect ratio is made too low it becomes difficult to control the weanng process and hence it iB desirable that the aspect ratio be at least 1.5:1, and preferably at least 2.0:1. A desirable range for the aspect ratio iB from about 4:1 to about 10:1. Currently available weaving equipment appear6 to be able to handle fibers with an aspect ratio of up to about 100:1. The fiber cross section also need not be simply ~ubstantially rectangular. It i6 also of advantage to use the grooved flattened monofilament warp yarns described by Jackson, W0 9V04374.

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In the preceding discussion of the figures it is a6sumed that all of the flattened monofilament warp yarn6 are the same. This i6 preferred, as it simplifies weaving, but it i8 not nece6sary. Warp yarn6 which are not flattened monofilaments can be included, but this iB not recommended, especialb in the paper side of the fabric. The dewatering capabilitie6 of the fabric will likely be impaired, and the risk of paper marking enhanced.
Consequently it is preferred that at least the majority, preferaUy F.ubstantially all, and most preferably all of the warp yarns are flattened monofilamen't yarns. It is al60 most convenient if the flattened monofilaments in each of the different layers of warp ya~s are of substantially the same width and thickness.

A fabric according to this invention can be woven either as a ~losed endles~ loop, or as a continuous run of fabric which is then seamed in some WO 93~01350 PCT/CA91/00247 ~ ~ 1 1 2 4 way to provide the required }oop. In a closed loop fabric the flattened monofilament warp yarns lie in the cro~s-machine direction, that i~
substan~ally at a right angle to the direction in which the paper web move~. In a con~nuous run of fabric, the flattened monofilament warp ya~ns lie in the machine direction of 1 he fabric substantially parallel to the direction of movement of the paper web.
,

Claims

What is claimed is:

1. A woven dewatering fabric, for the press section of a papermaking machine, having a first side and a second side, one of which constitutes the paper side of the fabric, and the other of which constitutes the press roll side of the fabric, and having long exposed floats of flattened monofilament warp yarns on the first side of the fabric, wherein:
(i) the aspect ratio of the flattened monofilament warp yarns is at least 1.5:1;
(ii) the fabric weave includes at least two distinct layers of warp yarns each including flattened monofilament warp yarns, only one of which provides the exposed first side floats;
(iii) the fabric weave further includes at least one layer of weft yarns; and (iv) the fill factor for each of the distinct layers of flattened monofilament warp yarns is at least about 45%.

2. A fabric according to claim 1 wherein the first side exposed floats of flattened monofilament warp yarns have a float ratio expressed by the formula x/y, wherein (i) "x" represents the number of weft yarns in a weft layer on the first side of the fabric in a single weave pattern repeat which are on the inside of the fabric with respect to a particular flattened monofilament warp yarn, and supporting that warp yarn; and (ii) "y" represents the total number of weft yarns in the weft layer on the first side of the fabric in a single weave pattern repeat;

and wherein for a majority of the first side exposed floats of flattened monofilament warp yarns:
(iii) x is greater than one; and (iv) x is greater than one-half of y.

3. A fabric according to claim 1 including two distinct layers of flattened monofilament warp yarns.

4. A fabric according to claim 1 including three distinct layers of flattened monofilament warp yarns.

5. A fabric according to claim 1 including one layer of weft yarns.

6. A fabric according to claim 1 including two layers of weft yarns.

7. A fabric according to claim 3 further including one layer of weft yarns.

8. A fabric according to claim 3 further including two layers of weft yarns.

9. A fabric according to claim 4 further including two layers of weft yarns.

10. A fabric according to claim 1 wherein each distinct layer of flattened monofilament warp yarns is interlaced with a single set of weft yarns, which are joined together in the weave by a binder yarn.

11. A fabric according to claim 1 wherein the first side of the fabric, including the long exposed floats, is the paper side of the fabric, and the second side is the press roll side of the fabric.

12. A fabric according to claim 1 wherein the second side of the fabric is the paper side of the fabric, and the first side, including the long exposed floats, is the press roll side of the fabric.

13. A fabric according to claim 11 further including a porous layer attached to the paper side of the fabric.

14. A fabric according to claim 12 further including a porous layer attached to the paper side of the fabric.

15. A fabric according to claim 11 further including a porous layer attached to both the paper side and the press roll side of the fabric.

16. A fabric according to claim 12 further including a porous layer attached to both the paper side and the press roll side of the fabric.

17. A fabric according to claim 13 wherein the porous layer is a staple fiber batt.

18 A fabric according to claim 14 wherein the porous layer is a staple fiber batt.

19. A fabric according to claim 15 wherein the porous layers are staple fiber batts.

20. A fabric according to claim 16 wherein the porous layers are staple fiber batts.

21. A fabric according to claim 17 wherein the batt is attached by needle punching, and the batt fibers are oriented substantially in a direction perpendicular to the flattened monofilament warp yarns.

22. A fabric according to claim 17 wherein the batt is attached by needle punching, and the batt fibers are oriented substantially in a direction parallel to the flattened monofilament warp yarns.

23. A fabric according to claim 18 wherein the batt is attached by needle punching, and the batt fibers are oriented substantially in a direction perpendicular to the flattened monofilament warp yarns.

24. A fabric according to claim 18 wherein the batt is attached by needle punching, and the batt fibers are oriented substantially in a direction parallel to the flattened monofilament warp yarns.

25. A fabric according to claim 19 wherein the batts are attached by needle punching and the batt fibers are oriented substantially perpendicular to the flattened monofilament yarns.

26. A fabric according to claim 19 wherein the batts are attached by needle punching and the batt fibers are oriented substantially parallel to the flattened monofilament yarns.

27. A fabric according to claim 19 wherein the batts are attached by needle punching, and the batt fibers in the paper side batt are oriented in a direction substantially perpendicular to the flattened monofilament warp yarns, and the batt fibers in the press roll side are oriented in a direction substantially parallel to the flattened monofilament warp yarns.

28. A fabric according to claim 19 wherein the batts are attached by needle- punching, and the batt fibers in the paper side batt are oriented in a direction substantially parallel to the flattened monofilament warp yarns, and the batt fibers in the press roll side are oriented in a direction substantially perpendicular to the flattened monofilament warp yarns.

29. A fabric according to claim 20 wherein the batts are attached by needle punching and the batt fibers are oriented substantially perpendicular to the flattened monofilament yarns.

30. A fabric according to claim 20 wherein the batts are attached by needle punching and the batt fibers are oriented substantially parallel to the flattened monofilament yams.

31. A fabric according to claim 20 wherein the batts are attached by needle punching, and the batt fibers in the paper side batt are oriented in a direction substantially perpendicular to the flattened monofilament warp yarns, and the batt fibers in the press roll side are oriented in a direction substantially parallel to the flattened monofilament warp yarns.

32. A fabric according to claim 20 wherein the batts are attached by needle punching, and the batt fibers in the paper side batt are oriented in a direction substantially parallel to the flattened monofilament warp yarns, and the batt fibers in the press roll side are oriented in a direction substantially perpendicular to the flattened monofilament warp yarns.

33. A fabric according to claim 2 wherein the float ratio is the same for all of the exposed floats.

34. A fabric according to claim 2 wherein the float ratio is not the same for all of the exposed floats.

35. A fabric according to claim 2 wherein the float ratio is no more than 9/10.

36. A fabric according to claim 2 wherein the float ratio is from 5/8 to 9/10.

37. A fabric according to claim 2 wherein the float ratio is from 3/4 to 7/8.

38. A fabric according to claim 1 wherein the fill factors for each of the distinct layers of warp yarn are the same.

39. A fabric according to claim 1 wherein the fill factors for each of the distinct layers of warp yarn are not the same.

40. A fabric according to claim 1 wherein the fill factor for at least one of the distinct layers of warp yarns is at least 60%.

41. A fabric according to claim 1 wherein the fill factor for at least one of the distinct layers of warp yarns is at least 80%.

42. A fabric according to claim 1 wherein the fill factor for at least one of the distinct layers of warp yarns is at least 85%.

43. A fabric according to claim 1 wherein all of the flattened monofilament warp yarns have the same aspect ratio.

44. A fabric according to claim 1 wherein all of the flattened monofilament warp yarns do not have the same aspect ratio.

45. A fabric according to claim 1 wherein at least one distinct layer of flattened monofilament warp yarns has an aspect ratio of at least about 2:1.

46. A fabric according to claim 1 wherein at least one distinct layer of flattened monofilament warp yarns has an aspect ratio of from at least about 4:1 to less than about 10:1.

47. A dewatering fabric according to claim 1 woven as a closed endless loop.

48. A dewatering fabric according to claim 47 including a seam.

49. A dewatering fabric according to claim 1 woven as a continuous run and seamed to provide a loop.

50. A fabric according to claim 1 wherein in at least the distinct layer of warp yarns providing the paper side long exposed floats the majority of the warp yarns are flattened monofilament yarns.

51. A fabric according to claim 1 wherein in at least the distinct layer of warp yarns providing the paper side long exposed floats substantially all of the warp yarns are flattened monofilament yarns.

52. A fabric according to claim 1 wherein in at least the distinct layer of warp yarns providing the paper side long exposed floats all of the warp yarns are flattened monofilament yarns.

53. A fabric according to claim 1 wherein in each of the distinct layers of warp yarns the majority of the warp yarns are flattened monofilament yarns.

54. A fabric according to claim 1 wherein in each of the distinct layers of warp yarns substantially all of the warp yarns are flattened monofilament yarns.

55. A fabric according to claim 1 wherein in each of the distinct layers of warp yarns all of the warp yarns are flattened monofilament yarns.