WO2013023276A1

WO2013023276A1 - Embossing fabric including warp yarn sets

Info

Publication number: WO2013023276A1
Application number: PCT/CA2012/000757
Authority: WO
Inventors: Derek Chaplin
Original assignee: Astenjohnson, Inc.
Priority date: 2011-08-15
Filing date: 2012-08-14
Publication date: 2013-02-21
Also published as: CA2748789A1

Abstract

A woven industrial fabric for filtration and conveyance comprises at least one set of weft yarns, and one set of warp yarns, comprising a plurality of groups of warp yarns. Each group comprises an identical number of at least two warp yarns. For each group the warp yarns together follow an identical coplanar path; are retained in lateral adjacency to provide a profile comprising a profile height above exposed adjacent portions of the weft yarns in the product conveying surface, the profile height being between 50% and 100% of a height of each warp yarn in the group; and are dimensioned such that a ratio of a width of the group in the product conveying surface to a height of the group is at least 2:1. The profile provides improved embossing properties to impart topography to sheets carried by the fabric in formation or through air drying.

Description

EMBOSSING FABRIC INCLUDING WARP YARN SETS

FIELD OF THE INVENTION

This invention relates to industrial textiles for filtration or conveyance, such as papermakers' fabrics. In particular, the invention relates to woven embossing fabrics whose component yarns are interwoven according to a pattern which will impart a macroscopic topography onto cellulosic products which are formed or conveyed thereon, and more particularly such fabrics in which warp yarns are arranged in groups of at least two yarns which are interwoven together according to the same path and pattern in the fabric and present an aspect ratio for each yarn set of at least 2: 1 and a ribbed surface to the sheet.

BACKGROUND OF THE INVENTION

Papermaker's fabrics woven using various arrangements of paired or similar sets of yarns are known, for example, as disclosed in US 2,088,447 and US 2,269,869 (both to Specht); US 3,143,150 (Buchanan); US 3,167,281 (Hill); and US 5,465,764 (Eschmann et al.). It is known to provide paired machine direction (MD) yarns, for example to provide a fabric having a tight weave (i.e. low air permeability), as disclosed in US 5,799,708 (Josef), which discloses a single layer fabric in which paired flattened yarns are provided in a pattern selected to present a paper side surface which is as smooth as possible. It is also known to use paired MD yarns to minimize drainage and crossover point topographical markings, as disclosed in US 6,953,065 (Martin et al.).

It is also known, for example from US 4,592,396 (Borel et al.), to use paired weft so as to allow the paper or product side surface (PS) to be as flat and smooth as possible; and from US 4,636,426 (Fleischer) to arrange either, or both, the warp and weft yarns in a side-by- side paired relationship, preferably glued together, so as to improve sheet release and reduce wire mark without having to use yarns having a generally rectangular cross-sectional shape. It is also known from US 5,429,686 (Chiu et al.) to use high, long warp floats in a through- air dryer (TAD) fabric to produce a quilted effect in the paper, by providing a so-called "sculpture layer" which contacts the web and embosses a pattern upon it.

US 7,1 14,529 (Johnson et al.) discloses a TAD fabric woven so that the warp and weft yarns are stacked in the fabric having a warp fill of at least 100% and a weft fill of at least 75%. The yarns are interwoven so that the warp are set above the fabric plane by 0.3 to 1.5 times the thickness of the yarns and so that diagonal apertures are formed within the fabric to

3 2

produce a high air permeability of at least about 7300 m /m /h. The fabric design is particularly suited for the production of a high bulk imprinted (patterned) paper product; the warp yarns are not arranged in sets or pairs.

It is known from US 7,121 ,306 (Harrison) to provide yarn assemblies of two or more vertically stacked warp or weft yarns interwoven as one yarn (i.e. each yarn follows the same weave path as its immediately adjacent neighbor so as to be in generally continuous, contiguous contact with each other substantially throughout the fabric). It is also known from US 7,740,029 (Hodson et al.) to use weft yarns which are arranged in pairs and weave as one through a dryer fabric, for the purpose of providing increased sheet contact, decreased weaving time and reduced air permeability.

For bulk sheet products such as towel and tissue, it is known to emboss the sheets by providing a profiled upper surface to the conveying fabrics. Many prior art embossing fabrics, such as those intended for through air drying and forming applications, are woven using generally flat or rectangular warp or weft yarns so as to provide suitable contact area between the sheet and fabric to enable sheet handling and release characteristics. However, as the majority of industrial textiles of this general nature, such as papermaking fabrics not for embossing, are woven using circular warp yarns, rethreading the loom to include rectangular warp yarns is disadvantageous^ time-consuming.

SUMMARY OF THE INVENTION

It has now been found that weave patterns in which the warp yarns are arranged in groups of two or more yarns which are interwoven together according to the same path and pattern in the fabric, and present an aspect ratio for each yarn group of at least 2:1, and present a profile above the weft yarns in the paper side surface of the fabric by an amount between 50% and 100% of the height of the individual warp yarns, are particularly advantageous in the production of patterned sheets such as towel and tissue. The grouping of two or more warp yarns, preferably but not necessarily of circular cross- section, so that they interweave together throughout the fabric, as a set, allows for a replication of the aspect ratio and effect previously provided by using a single rectangular cross-section monofilament warp yarn having the same aspect ratio and interwoven in the same manner. The weave patterns of the invention have the further advantages that the contact area between the sheet and the fabric can be increased as desired by increasing the number of warp yarns weaving in parallel adjacent paths; and the resulting structure can now include MD oriented striations (i.e. the space between the yarns) which provide contamination resistance effects similar to those known to be provided by ribbed or grooved yarn profiles, such as those described in US 6,773,786 (Kuckart).

This also allows for the use of looms already threaded with round warp yarns. As those yarns and looms are of appropriate size and are suitably equipped to weave embossing fabrics, they may now advantageously be used to produce the fabrics of the invention, eliminating the previous necessity, noted above, of having to change the existing warp system from round to flat yarns in order to weave such a fabric. This provides for the advantage of using a single warp platform for these and other fabrics, such as disclosed in WO 201 1/011676 (Chaplin et al.).

The invention therefore seeks to provide a woven industrial fabric for at least one of filtration and conveyance, the fabric having a product conveying surface, being woven to a repeating weave pattern and comprising

(i) at least one set of weft yarns; and (ii) one set of warp yarns, comprising a plurality of groups of warp yarns, each group comprising an identical number of at least two warp yarns, wherein for each group the warp yarns

(a) together follow an identical coplanar path; (b) are retained in lateral adjacency to provide a profile comprising a profile height above exposed adjacent portions of the weft yarns in the product conveying surface, wherein for each group of warp yarns the profile height is between 50% and 100% of a height of each warp yarn in the group; and

(c) are dimensioned such that a ratio of a width of the group in the product conveying surface to a height of the group is at least 2: 1.

In the fabrics of the invention, the warp yarns comprise groups of at least two or three, or possibly more, individual yarns. The warp yarns of a group are woven together, in direct adjacency and in the same manner. The yarns in each group follow identical coplanar paths throughout the fabric and, as a group, provide an effective aspect ratio (which is the ratio of the total width of all of the yarns in one group, to the height of the group) of at least 2:1. The aspect ratio of each set of yarns simulates a single rectangular cross-section yarn having the same aspect ratio. Where the warp yarns have a circular cross-section, or a flattened cross- section with rounded edges, each yarn group is effectively ribbed due to the adjacency of the yarns, and the ribs are effective in releasing contaminants and other undesirable foreign matter from the fabric surface during cleaning cycles.

Preferably, the set of warp yarns comprises only the groups of warp yarns.

In general, sets or groupings of two or more adjacent warp yarns interwoven as a pair, triplet, quadruplet, simulate in the fabric a single rectangular yarn with dimensions

x h where w is the width of each individual yarn in the group, h is the height of the yarn and where n is the number of warp yarns in the group. Each group will thus have an aspect ratio of nw. h.

For example, two or three circular cross-section warp yarns, each having a diameter of e.g. 0.22mm, could be used to replicate the effect provided by a single rectangular warp yarn whose aspect ratio is 2:1 (i.e. two circular cross-section warp yarns each having diameters of 0.22mm provide a warp yarn group which measures 0.44 x 0.22mm) or 3:1 (i.e. three circular cross-section warp yarns each having a diameter of 0.22mm provide a warp yarn group which measures 0.66 x 0.22mm). The fabrics of the invention are flat woven according to a pattern requiring at least 10 sheds in the loom using circular cross-section polymeric monofilament MD warp yarns and cross- machine direction (CD) weft yarns arranged so as to provide a warp fill of approximately 95% to 1 10% in the fabric following heatsetting, preferably between 98% and 104%. The warp yarns may be arranged on either one or two beams in the loom for weaving. Preferably, the weft yarns have a substantially circular cross-section, having a diameter which is at least twice the height of each warp yarn.

Preferably, the warp yarns have a cross-sectional configuration selected from substantially circular and substantially rectangular. Preferably, the profile provided by the warp yarns of a group comprises striations extending in a machine direction of the fabric. In one embodiment of the invention, the warp yarns are interwoven with a single set of weft yarns to provide a single layer fabric.

In other embodiments, the warp yarns are interwoven with first and second sets of weft yarns to provide a double layer fabric, in which the first set of weft yarns are located entirely on the paper or product side surface (PS) of the fabric, and the second set of weft yarns are located entirely on the opposing machine side surface (MS) of the fabric. The weft yarns of the first set may be arranged so as to be vertically stacked with corresponding weft yarns of the second set in the fabric (i.e. the PS:MS weft ratio is 1 : 1).

In an alternative double layer fabric construction, not all of the weft yarns of the first system are vertically stacked over corresponding weft yarns of the second weft system. Additional weft yarns may be included in the PS of the fabric; in a version of this embodiment, additional weft yarns are provided so as to effectively double the number of weft yarns in the PS, to provide a fabric in which the PS:MS weft yarn ratio is 2: 1. Other ratios can be selected to provide the desired weft yarn ratio according to the intended end use of the fabric, for example ratios of 1.5 : 1 , or e.g. 3 : 1 or higher. Weft yarn ratios greater than 1 : 1 will provide extra support for the papermaking fibers in the sheet conveyed by the fabric and may be used to adjust air permeability. In double layer fabrics where the weft yarn ratio is greater than 1 : 1, some of the weft yarns of the first set will be vertically stacked over corresponding weft yarns of the second set.

In the fabrics of the invention, the groups of warp yarns are interwoven with the weft yarns according to patterns which provide for a weft float length of between one and eleven warp yarn groups on the MS of the fabric.

As discussed further below in relation to the drawings, the patterns for the fabrics of the invention provide for diagonal apertures for fluid flow through the fabric.

The polymeric warp and/or weft yarn material is preferably a polyester such as polyethylene terephthalate (PET) which is optionally heat or hydrolysis stabilized; in high temperature environments such as may be found in a through-air dryer, it may also be beneficial to use a heat resistant material such as polyphenylene sulphide (PPS) in either, or both, the warp and weft positions in the fabric. However, the invention is not so limited, and polymers such as are commonly used in industrial textiles intended for papermaking applications may be utilized in either the warp or weft yarns from which the fabric is made. When the intended end use of the fabric is in a through-air dryer type application, it may be preferred to use known hydrolysis or heat stabilized materials so as to increase the service life of the fabric. Where the intended end use of the fabric is in the forming section, where heat and hydrolysis are not major concerns, it may be appropriate to use nylons, various polyesters, or blends of PET and thermoplastic polyurethane such as are known in the art, for example as disclosed in US 5,169,71 1 (Bhatt et al.) and US 5,502,120 (Bhatt et al.).

However, in all cases, the materials and dimensions for the yarns, and the fabric processing conditions, will be selected and adjusted so that the weft yarns have a greater resistance to crimping than the warp yarns, so as to ensure that the warp yarns are raised above the plane of the weft yarns in the woven fabric to provide the required amount of profile as discussed above, and to separate the warp yarn groups vertically as they pass under or over the weft yarns, in order to provide for appropriate diagonal apertures through the fabric for the desired fluid flow.

An important further benefit of the present invention is the ability provided to the fabric manufacturer to now weave the novel fabrics using an existing warp "platform" that may already be provided to a loom that is equipped with essentially circular cross-sectional shaped yarns. Through-air dryer or embossing fabrics are frequently woven using warp yarns having either a rectangular or square cross-sectional shape so as to provide a desired contact surface area to the sheet. Sometimes these fabrics are "surfaced", generally using abrasive means such as sanding, so as to increase their paper side surface contact area. Fabrics woven according to the weave patterns and yarn arrangements of the present invention can provide a high PS surface contact area without re-threading the loom from circular to rectangular cross-sectional shaped yarns, although they may be so woven if desired. When fabrics according to the invention are woven using yarns having a circular cross-sectional shape, or a flattened shape with rounded edges, the yarn groups provide a further benefit in that the direct adjacency of the warp yarns in each group results in the group presenting an effective ribbed shape to the sheet which allows the fabric to both easily shed contaminants and release the sheet at the appropriate transfer point in the

manufacturing process. In addition, the fabrics of the invention can be surfaced to further increase their contact area with the sheet, if desired. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the drawings, in which:

Figure la is a cross-sectional view along the weft yarns through a fabric in an embodiment of the invention;

Figure lb is a top view of the fabric of Figure la; Figure lc is a bottom view of the fabric of Figure la;

Figure I d is a cross-sectional view along the warp yarns of the fabric of Figure la; Figure le is a depiction of an approximate three-dimensional representation of the fabric of Figure la;

Figure 2 is a cross-sectional view along the weft yarns through a fabric in a second embodiment of the invention; Figure 3a is a 24-shed weave diagram for a double layer embossing fabric in a third embodiment of the invention;

Figure 3b is a diagram showing an approximation of the paper side surface embossing pattern of a fabric woven according to the pattern shown in Figure 3 a;

Figure 3c is a photograph of a tissue sheet sample formed and embossed on a fabric woven according to the pattern shown in Fig. 3a having a paper side surface as shown in Figure 3b;

Figure 4a is a 24-shed weave diagram for a double layer embossing fabric in a fourth embodiment of the invention;

Figure 4b is a diagram showing an approximation of the paper side surface embossing pattern of a fabric woven according to the pattern shown in Figure 4a; Figure 4c is a photograph of a tissue sheet sample formed and embossed on a fabric woven according to the pattern shown in Fig. 4a having a paper side surface as shown in Figure 4b;

Figure 5a is a 24-shed weave diagram for a double layer embossing fabric in a fifth embodiment of the invention;

Figure 5b is a diagram showing an approximation of the paper side surface embossing pattern of a fabric woven according to the pattern shown in Figure 5a;

Figure 5c is a depiction of an approximate three-dimensional representation of a fabric constructed according to the weave diagram shown in Figure 5a;

Figure 6a is a 24-shed weave diagram for a double layer embossing fabric in a sixth embodiment of the invention; Figure 6b is a diagram showing an approximation of the paper side surface embossing pattern of a fabric woven according to the pattern shown in Figure 6a;

Figure 6c is a depiction of a three-dimensional representation of a fabric constructed according to the weave diagram shown in Figure 6a; Figure 6d is a photograph of a tissue sheet sample formed and embossed on a fabric woven according to the pattern shown in Fig. 6a;

Figure 7a is a 24-shed weave diagram for the double layer embossing fabric of Figure la;

Figure 7b is a diagram showing an approximation of the paper side surface embossing pattern of a fabric woven according to the pattern shown in Figure 7a; Figure 7c is a photograph of a tissue sheet sample formed and embossed on a fabric woven according to the pattern shown in Fig. 7a;

Figure 8a is a 24-shed weave diagram of a single layer embossing fabric in a seventh embodiment of the invention;

Figure 8b is a top view of the fabric of Figure 8a; Figure 8c is a bottom view of the fabric of Figure 8a;

Figure 8d is a cross-sectional view along the warp yarns of the fabric of Figure 8a;

Figure 8e is a cross-sectional view along the weft yarns of the fabric of Figure 8a; and

Figure 8f is a depiction of an approximate three-dimensional representation of the fabric of Figure 8a. DETAILED DESCRIPTION OF THE DRAWINGS

Figure l a is a cross-sectional view of a portion of a double layer fabric 1 in an embodiment of the invention, the view being taken along the weft yarns 5, indicated as yarns 5a and 5b. In this embodiment, each group 20 of warp yarns such as 20a, 20b, 20c, 20d and 20e consists of two yarns 10, and the figure shows them as they would appear in a cross-section as if interwoven with representative weft yarns 5a and 5b. As shown in Figure la, weft yarns 5a and 5b are located so as to be in generally vertically stacked alignment with one another. Warp yarns 10 are arranged as groups 20 of two mutually adjacent yarns indicated in Figure la as groups 20a, 20b, 20c, 20d and 20e; each of these groups is interwoven with weft yarns 5 so that each warp yarn 10 of each group 20 is interwoven as one to pass over and under all of weft yarns 5 in fabric 1. As shown in Figure 1 a, all of warp yarns 20 and weft yarns 5 have a generally circular cross-sectional shape; this is not necessary, and it would be within the scope of the invention to replace the generally circular shaped warp yarns 10 with similar yarns having a generally rectangular or square cross-sectional shape. Warp yarns 10 and yarn groups 20 are interwoven in close adjacency to provide a warp fill in the fabric of from about 95% to about 105%. The term "warp fill" refers to the amount of warp yarns the fabric can dimensionally accommodate without distortion. It can be seen that the relatively significantly larger weft yarns 5a and 5b have relatively little crimp; this allows for warp yarn groups 20a, 20b, 20c to provide a profile to the fabric above weft yarns 5a, having a profile height p, which is between 50% and 100%) of the cross-sectional height of individual warp yarns 10. The interweaving arrangement of warp yarn groups 20 with weft yarns 5a and 5b provides for diagonal apertures such as 30 to be formed in fabric 1 allowing for movement of fluid though the fabric structure, as discussed below in relation to Figures 5c and 6c. Figure lb is a top view of fabric 1 of Figure la, showing paper side surface 2, in which warp yarn groups 20, comprising pairs of warp yarns 10, interweave with weft yarns 5a to create the desired profiled surface.

Figure l c is a bottom view of fabric 1 of Figure la, showing machine side surface 3, in which warp yarn groups 20 interweave with weft yarns 5b. The long floats of large weft yarns 5b provide increased abrasion resistance to fabric 1 , and protection for smaller warp yarns 10.

Figure Id is a cross-sectional view taken along warp yarns 10 of fabric 1 of Figure l a, showing the paths of warp yarn groups 20 as they interweave with weft yarns 5a, 5b, providing a profile in paper side surface 2. Figure 1 e is a depiction of an approximate three-dimensional representation of fabric 1 of Figure la, showing warp yarn groups 20a, 20b, 20c as they interweave with weft yarns 5a, 5b. As noted above, the weave pattern provides diagonal apertures 30 for fluid flow through fabric 1. Figure 2 is an illustration similar to Figure la, being a cross-sectional view of a double layer fabric la in another embodiment of the invention. This view is taken along weft yarns 5, indicated as generally vertically stacked yarns 5a and 5b. In this embodiment, each group 22 of warp yarns such as 22a, 22b and 22c consists of three yarns 10, having a substantially rectangular cross-section, and the figure shows them as they would appear in a cross-section through a portion of a fabric of the invention as if interwoven with the representative weft yarns 5a and 5b. In this embodiment, each of the three warp yarns 10 in the groups 22 is arranged so as to be mutually adjacent to one another and, as a group 22, are interwoven with weft yarns 5 according to the same pattern and path through the fabric so that each warp yarn 10 of each group 22 passes together with the others in the group over and under all of weft yarns 5a and 5b in the fabric. As in Figure la, warp yarns 10 of warp yarn groups 22 are interwoven in close mutual adjacency to provide a warp fill in the fabric of from about 95% to about 105%). It can be seen that the relatively larger weft yarns 5a and 5b are minimally crimped by the warp yarn groups 22; this allows for warp yarn groups 22a, 22b, 22c to provide a profile to the fabric above weft yarns 5a, having a profile height p, which is between 50% and 100%> of the cross-sectional height of individual warp yarns 10. Similarly, the interweaving arrangement of warp yarn groups 22 with weft yarns 5a and 5b provides for diagonal apertures 35 to be formed in the fabric la, such as between warp groups 22a and 22b, which allow for movement of fluid though the fabric structure.

Figure 3a is a weave diagram for a 24-shed double layer embossing fabric 100 in a third embodiment of the invention. As is conventional in weave diagrams such as these, darkened squares indicate locations in the pattern where warp yarns 10 pass over weft yarns 5 as seen from the paper side surface, while white squares indicate locations where the warp yarns pass under a weft yarn. In this and in the other weave diagrams herein (Figures 4a, 5a, 6a and 7a), fully black squares show where a warp yarn 10 passes over a PS weft yarn such as 5a, while grey squares show where the same warp yarns 10 pass over a MS weft yarn such as 5b; white squares designate that the warp yarns pass under a weft yarn. In Figure 3a, warp yarns 10 are numbered across the diagram from 1 to 24, while weft yarns 5 are numbered from 1 to 16 down the diagram. Fabric 100 could be woven according to the indicated pattern using an industrial loom equipped with two back beams from which warp yarns 10 would be paid out as they are interwoven with weft yarns 5.

In the weave diagram presented in Figure 3a, warp yarns 10 are organized in groups consisting of two yarns arranged in the manner described in relation to Figure la and are interwoven with weft yarns 5 according to the pattern provided. For example, warp yarns numbered 1 to 6 and 13 to 18 all pass over weft 1 to provide an embossing pattern to the PS surface of the fabric consisting of three warp yarn groups, such as 20a, 20b and 20c in Figure 1 a. The pattern presented to the PS surface of the eventual fabric 100 by these three warp yarn groups is represented in Figure 3b, which shows the arrangement of warp yarn groups 20 as they pass over PS weft yarns 5a in the manner described in relation to Figure la. The remaining warp yarns 7 to 12 and 19 to 24 pass under weft yarn 1 on the opposing machine side of the fabric. The pattern then continues in the manner shown in Figure 3a. Inspection of this weave diagram further reveals that warp yarn groups 20 appear on the paper side surface at every second weft in the repeating pattern, so that the 16 weft yarns 5 in the fabric 100 provide for 8 occurrences of paper side knuckles formed by the yarn groups 20 which fashion the overall embossing pattern of the fabric 100. The significance of this is discussed below in relation to Figure 3b.

Figure 3b is an illustration depicting an approximation of the paper side surface embossing pattern 1 10 of a fabric 100 woven according to the overall 24-shed pattern provided in Figure 3a and showing eight repeats of the PS surface embossing pattern. As shown in Figure 3b, two repeats occur across the diagram, and four down the diagram. As in Figure 3a, warp yarns 10 are arranged across the top of the diagram and are oriented in the intended machine direction of fabric 100 as indicated by the arrow MD, while weft yarns 5 are arranged perpendicularly to this direction and from left to right across the diagram. It will be apparent that the black squares of Figure 3b correspond to the black squares of Figure 3a (i.e. they provide a representation of the embossing pattern 1 10 of the paper side surface of the fabric upon which the sheet is formed and conveyed through the papermaking machine). The black squares thus indicate the "knuckle" pattern of warp yarns 10 of warp yarn groups 20 when they are interwoven with the PS weft yarns such as 5a in fabric 100 according to the pattern provided in Figure 3a.

Figure 3c is a photograph of a tissue sheet sample 200 formed and embossed on embossing fabric 100 which is woven according to the pattern shown in Fig. 3a, and which has a paper side surface pattern as shown in Figure 3b. As can be seen from the photograph of Figure 3c, the warp yarn groups in the fabric 100 (similar to 20 in Figure la) impart a surface topography to sheets formed and conveyed by the fabric. This topography includes elevated areas such as 210 and depressions such as 220 which will assist in imparting absorbency and desirable tactile properties to tissue products made using the fabric 100.

The elevated areas 210 and depressions 220 in sheet sample 200 are formed as a result of the profile height of the knuckles created by warp yarn groups 20 in the paper side surface and which are elevated above weft yarns 5 a in the same surface. As the sheet is formed on the fabric 100, the individual fibers will simultaneously be deposited over the tops of both warp yarn groups 20 and PS weft yarns 5a; due to the difference in relative elevation between these knuckles and the PS weft surfaces, a topography is imparted to the sheet which topography mirrors to an extent the paper side surface profile of the fabric. This non-planar surface topography is desirable in paper products intended for use as towelling, tissue and similar applications where absorbency and strength are important. The profile height (similar to that shown as p in Figure la) of warp yarn groups 20 above PS weft yarns 5a at the tops of the knuckles is between 50% and 100% of the cross-sectional height of the individual warp yarns 10 in warp yarn groups 20. As previously noted, these warp yarn groups 20 consisting of at least two or three yarns 10 are formed as a consequence of weaving warp yarns 10 in direct adjacency and in the same manner to provide an effective aspect ratio (i.e. the ratio of the width of the warp yarn group relative to its overall height) of each group that is at least 2: 1. This aspect ratio of a warp yarn group 20 effectively simulates the aspect ratio of a single monofilament yarn having a rectangular cross-sectional shape, and thus serves to both increase the contact area between the fabric and sheet that is formed using it, and provide the desired profile height of warp yarn group 20 above PS weft yarns 5 a.

Figure 4a is a weave diagram for a 24-shed double layer embossing fabric 101 in a fourth embodiment of the invention. As shown in the diagram, warp yarns 10 are identified from 1 to 24 across the top of the diagram and are oriented vertically while weft yarns 5, identified as 1 to 16, are arranged horizontally from left to right and perpendicularly to warp yarns 10, as previously described in relation to Figure 3a. As in Figure 3a, warp yarns 10 of fabric 101 shown in Figure 4a are organized in groups each consisting of two yarns arranged in the same manner as shown in Figure 1 a. The pattern shown in Figure 4a differs from that provided in Figure 3a in that the number of warp knuckles forming the paper side embossing pattern in Figure 4a is two less than the number of knuckles used in the embossing pattern of Figure 3a. For example, warp yarns numbered 1 to 4 and 13 to 16 all pass over weft 1 to provide an embossing pattern to the PS surface of fabric 101 consisting of 2 adjacent warp yarn groups, such as 20a and 20b in Figure la. This effect is illustrated in Figure 4b, which is a diagram showing an approximation of the paper side surface embossing pattern 1 1 1 of a fabric woven according to the overall 24-shed pattern shown in Figure 4a. Inspection of Figure 4b shows that embossing pattern 1 1 1 of the fabric is similar to embossing pattern 1 10 provided in Figure 3b except that there is one fewer warp yarn group at each PS weft (i.e. there are only two groups at each knuckle in Figure 4b, while there are three at each knuckle of the representation in Figure 3b). The overall effect of this difference in the weave patterns of the two fabrics shown in Figures 3a and 4a is apparent when examining tissue sheets formed on each.

Figure 4c is a photograph of a tissue sheet sample 201 formed and embossed on a fabric woven according to the pattern shown in Fig. 4a, and having a paper side surface as shown in Figure 4b. Tissue sheet sample 201 includes elevated areas 21 1 and depressions 221 in its structure which appear more or less vertically continuous. In contrast, elevated areas 210 and depressions 220 in sheet sample 200 in Figure 3c are closer together and do not appear as vertically continuous. Sheet sample 201 will have different physical properties in comparison to sheet sample 200 and desired intended end use characteristics may dictate which of the two fabrics 100 or 101 will best accommodate those needs.

Figure 5a is a 24-shed weave diagram for a double layer embossing fabric 102 in a fifth embodiment of the invention. Warp yarns 10 are identified as 1 to 24 across the top of the diagram, and weft yarns 5 are identified as 1 to 20 down the diagram. In this embodiment, warp yarns 10 are arranged in groups 22 consisting of three yarns such as 22a, 22b and 22c, organized in a manner similar to that shown in Figure 2, and are interwoven with weft yarns 5 using a double beam loom. Figure 5b is a diagram showing an approximation of the paper side surface embossing pattern 1 12 of a fabric woven according to the overall 24-shed pattern shown in Figure 5a. Figure 5b shows approximately 6 repeats of the pattern as it would appear in the woven fabric.

Figure 5c shows a three-dimensional representation of fabric 300 constructed according to the weave diagram shown in Figure 5a and showing the paper side surface of such a fabric which includes the embossing pattern provided by Figure 5b. As can be seen in Figure 5c, fabric 300 includes two layers of vertically stacked weft yarns 5 of which weft 5a are located on the eventual paper side surface of the fabric 300, while weft 5b are located vertically below. Warp yarns 10 are arranged in groups of three warp yarns, each as shown at 22. The intended machine direction of the fabric is identified by the arrow labelled MD. As in the fabrics depicted in Figures 3a and 4a, warp yarn groups 22 are formed from individual warp yarns 10 which are woven in direct adjacency and in the same manner so as to pass, as a group, over and under weft yarns 5 of fabric 300. Warp yarns 10 of each group of warp yarns 22 are organized to provide an aspect ratio, as discussed above, of 3: 1, simulating the effect provided by a single rectangular cross-section yarn having a similar aspect ratio. In the representation shown in Figure 5c, it will also be apparent that the profile height of warp yarn groups 22 above weft yarns 5a in the paper side surface is between 50% and 100% of the height of any warp yarn in the group (similar to that shown as p in Figure l a). As can also be seen in Figure 5c, each of warp yarn groups 22 is effectively ribbed in appearance due to the adjacency of the individual yarns comprising the group. The weave design of this embodiment, including relatively larger sized weft yarns 5a and 5b as compared with warp yarns 10, separates warp yarns 10 vertically where they pass under or over weft yarns 5a, 5b, thus providing diagonal apertures 35 for fluid flow through fabric 300.

Figure 6a is a 24-shed weave diagram for a double layer embossing fabric 103 in a sixth embodiment of the invention. Warp yarns 10 are identified as 1 to 24 across the top of the diagram, and weft yarns 5 are identified as 1 to 24 down the diagram. Fabric 103 is woven using a double beam loom. Figure 6b is a diagram showing an approximation of the paper side surface embossing pattern 1 13 of a fabric woven according to the overall 24-shed pattern shown in Figure 6a. In Figure 6b, warp yarns 10 are arranged across the top of the diagram and weft yarns 5 are located vertically down the side. Figure 6c shows a three- dimensional representation of a fabric 400 constructed according to the weave diagram shown in Figure 6a, in which warp yarns 10 as warp yarn groups 20 interweave with weft yarns 5a and 5b. In the same manner as for the embodiment of Figure 5c, the weave design of this embodiment, including relatively larger sized weft yarns 5a and 5b as compared with warp yarns 10, separates warp yarns 10 vertically where they pass under or over weft yarns 5a, 5b, thus providing diagonal apertures 30 for fluid flow through fabric 300.

Figure 6d is a photograph of a tissue sheet sample 203 formed and embossed on a fabric woven according to the pattern shown in Fig. 6a, and showing elevated areas 213 and depressions 223. Figure 7a is a 24-shed weave diagram for a double layer embossing fabric 104 in the embodiment of the invention shown in Figures la to lc. Warp yarns 10 are identified as 1 to 24 across the top of the diagram, and weft yarns 5 are identified as 1 to 10 down the diagram. In this embodiment, warp yarns 10 are arranged in groups consisting of two warp yarns, and fabric 104 is woven using a double beam loom. Figure 7b is a diagram showing an approximation of the paper side surface embossing pattern of a fabric 1 14 woven according to the overall 24-shed pattern shown in Figure 7a. Figure 7c is a photograph of a tissue sheet sample 204 formed and embossed on a fabric woven according to the pattern shown in Fig. 7a, and showing elevated areas 214 and depressions 224. Figure 8a is a 24-shed weave diagram for a single layer embossing fabric 105 in a seventh embodiment of the invention. Warp yarns 10, arranged in groups of two, are identified as 1 to 24 across the top of the diagram, and weft yarns 5 are identified as 1 to 12 down the side of the diagram. Figure 8b is a top view of a single layer embossing fabric 500, constructed according to the weave diagram of Figure 8a, showing paper side surface 12, in which warp yarn groups 20 provide a desired profile above weft yarns 5. Figure 8c is a bottom view of fabric 500, showing machine side surface 13.

Figure 8d is a cross-sectional view along warp yarns 10 of fabric 500, showing the paths of warp yarns 10 as they interweave with the single set of weft yarns 5. Figure 8e is a cross- sectional view along weft yarns 5 of fabric 500, showing warp yarn groups 20 as they interweave with weft yarns 5, to provide the desired profile above weft yarns 5 in paper side surface 12.

Figure 8f is a depiction of an approximate three-dimensional representation of fabric 500, in which warp yarns 10 as groups 20 interweave with weft yarns 5. In the same manner as for the double layer embodiments of the invention (see e.g. Figure 5c), the weave design of this embodiment, including relatively larger sized weft yarns 5 as compared with warp yarns 10, separates warp yarns 10 vertically where they pass under or over weft yarns 5, thus providing diagonal apertures 30 for fluid flow through fabric 500.

Claims

WE CLAIM:

1. A woven industrial fabric for at least one of filtration and conveyance, the fabric having a product conveying surface, being woven to a repeating weave pattern and comprising

(a) together follow an identical coplanar path;

(b) are retained in lateral adjacency to provide a profile comprising a profile height above exposed adjacent portions of the weft yarns in the product conveying surface, wherein for each group of warp yarns the profile height is between 50% and 100% of a height of each warp yarn in the group; and

2. An industrial fabric according to Claim 1 , wherein the ratio is at least 3:1.

3. An industrial fabric according to Claim 1 or Claim 2, wherein the set of warp yarns comprises only the groups of warp yarns.

4. An industrial fabric according to any one of Claims 1 to 3, wherein the fabric has a warp fill of between 95% and 1 10%.

5. An industrial fabric according to Claim 4, wherein the warp fill is between 98% and 104%.

6. An industrial fabric according to any one of Claims 1 to 5, wherein the weft yarns have a substantially circular cross-section, having a diameter which is at least twice the height of each warp yarn.

7. An industrial fabric according to any one of Claims 1 to 6, wherein the warp yarns have a cross-sectional configuration selected from substantially circular and substantially rectangular.

8. An industrial fabric according to any one of Claims 1 to 7, wherein the profile provided by the warp yarns comprises striations extending in a machine direction of the fabric.

9. An industrial fabric according to any one of Claims 1 to 8, having one set of weft yarns and comprising a single layer fabric.

10. An industrial fabric according to any one of Claims 1 to 8, having two sets of weft yarns and comprising a double layer fabric.

11. An industrial fabric according to any one of Claims 1 to 10, comprising a papermaking fabric.

12. An industrial fabric according to Claim 1 1 , comprising a forming fabric.

13. An industrial fabric according to Claim 1 1, comprising a dryer fabric.

14. An industrial fabric according to Claim 13, comprising a through air dryer fabric.