WO2000012818A1

WO2000012818A1 - Tissue marking fabric

Info

Publication number: WO2000012818A1
Application number: PCT/GB1999/002793
Authority: WO
Inventors: Stewart Hay
Original assignee: Voith Fabrics Heidenheim Gmbh & Co. Kg.
Priority date: 1998-08-29
Filing date: 1999-08-24
Publication date: 2000-03-09
Also published as: EP1108086A1; GB9818823D0

Abstract

A tissue marking fabric comprises at least two warp yarn systems (5, 6) and one or two weft yarn systems (3, 4). The warp yarn systems are interlaced at spaced intervals, and extensive floats are provided either in the upper weft yarn system (3) extending in the cross-machine direction, or in the upper warp yarn system (14).

Description

TISSUE MARKING FABRIC

This invention relates to a papermaker's fabric intended primarily for

use in the production of patterned tissues, which may be used for example

as a forming or drying fabric in the process of tissue paper manufacture.

WO 96/35018 (Kimberly-Clark) describes the formation of patterns

in a paper or tissue sheet using an integral woven structure on the fabric

surface. The imprint in this case is caused by providing systematically

distributed densely woven areas in the fabric where drainage of water is

relatively slow. As disclosed in the said specification, the drainage may be

impeded by incorporation of additional filaments or fibres on top of or within

the forming fabric weave pattern, or by a film or coating which blocks or

fills void space within the fabric through which water could otherwise drain.

Over the areas of impeded drainage, a thinner layer of relatively long fibres

tends to be deposited, whilst shorter fibres migrate and are concentrated in

the area of more rapid drainage, producing a thicker, less translucent tissue

over the faster drainage areas.

One method of producing areas of different drainage rate is to provide

long yarn floats in the tissue contacting surface of the forming or drying

fabric. US 5,429,686 (Chiu) discloses a patterned fabric with long warp

floats provided as an additional sculpting layer superimposed upon the

normal fabric weave. These sculpting layer floats can produce a lineated or discrete area pattern. This disclosure also relates to relatively high, e.g.

over 65% warp cover fabrics, which makes for poor air permeability or

drainage.

WO 93/10304 (Nordiskafilt) relates to a papermachine fabric designed

to reduce marking of the paper or tissue web by a forming fabric comprising

at least two systems of warp threads and at least one system of weft

threads, wherein the warp thread systems are interconnected by interlacing

the yarns of one warp thread system with the yarns of the other, at least

once in each pattern repeat. In a single weft embodiment, extensive warp

yarn floats are produced by the yarns of the lower warp system on the

machine face of the fabric.

An object of the invention is to provide a tissue marking fabric

suitable for use in the wet end of a tissue machine as a forming wire, or as

a throughair drying fabric, which is capable of producing desired marking of

the tissue, but can be produced without use of supplementary or auxiliary

yarns to produce areas of altered drainage.

In accordance with the invention, a tissue marking fabric comprises

at least one weft yarn system and at least two warp yarn systems, at least

two of the warp yarn systems being interlaced with each other,

characterised by the provision of extensive yarn floats on the tissue

contacting face of the fabric in either a warp yarn system and/or a weft yarn system, the floats being provided by the interlacing yarns.

In a first embodiment, two weft yarn systems may be provided,

extending in the cross-machine direction. Two separate warp yarn systems

are in this case provided, one associated with the lower weft yarn system

and interwoven therewith, and the other associated with the upper weft

yarn system, and each yarn of which is at least partially interwoven with

the yarns of the upper weft yarn system, at least some of the warp yarns

of the second warp yarn system being passed below two or more of the

weft yarns of the lower weft yarn system. This has the effect of creating

weft yarn floats in the upper weft yarn system, which is on the tissue

contacting side of the fabric. The warp yarn systems are interlaced in the

region of normal weave.

In a second embodiment, a single weft yarn system is provided, with

a first warp yarn system associated therewith and interwoven with the weft

yarns. A second warp yarn system is provided comprising yarns which are

not interwoven with the weft yarns, but are interlaced with spaced knuckles

of the first warp system, for example at each third, fourth or fifth knuckle.

This produces extensive floats in the second warp yarn system which are

presented on the tissue contacting face of the fabric.

The interlacings between the yarns of the first and second warp yarn

systems may involve alternate right and left twists given to the second system warp yarns.

Two embodiments of fabric according to the invention will now be

described by way of example with reference to the accompanying drawings

wherein:-

Fig. 1 is a weave diagram of a first embodiment of tissue marking

fabric according to the invention; and

Fig. 2 is a weave diagram of a second embodiment of tissue marking

fabric according to the invention.

Fig. 1 shows a two-ply 10 shaft repeat weave fabric which has two

weft yarn systems 1 and 2, forming upper and lower fabric plies or layers.

In both Fig. 1 and Fig. 2, the tissue contacting surface of the fabric is

shown to the top, and the machine contacting weaving surface is shown to

the bottom. The first upper (tissue side) weft yarn system 1 comprises a

plurality of weft yarns 3a-3j. The second lower (machine side) weft yarn

system 2 similarly comprises a plurality of weft yarns 4a-4j, which are

disposed directly below the corresponding yarns 3a-3j of the first system 1 .

A plurality of warp yarns are woven with the lower system 2, a

representative one of which 5, is shown in the drawing. This is woven in

a standard 4: 1 weave pattern, and thus floats over four weft yarns of the

lower system, and is looped below one of the weft yams in the lower

system, in each weave repeat. Further warp yarns such as 6 are woven into the upper weft yarn

system, as shown in a 1 : 1 weave with the first five threads 3a-3e of a 10

shaft repeat, and then woven below the next five yarns 3f-3j of the upper

weft system, as shown. Successive warp yarns 6 may be stepped one

thread to the right or left with reference to the drawing. As a result, each

weft thread of the first yarn system, such as 3f-3j as shown in the drawing,

is exposed for example five warp yarns and thus floated in contact with the

tissue.

Yarn 6 and yarn 5 are interlaced once in each repeat, as shown

between weft yarns 3b and 4b.

Fig. 2 shows a single ply 8 shaft repeat weave fabric which has a

single weft yarn system 1 1 , with a plurality of weft yarns 12a-12h in each

repeat.

A system of warp yarns such as 13 is interwoven into the yarn

system 1 1 , in for example a 1 : 1 weave pattern as illustrated. The warp

yarns may be relatively displaced to the left or right of the drawing by one

weft thread at each pick, so that loop knuckles alternate in bridging weft

yarns.

A further layer of warp direction yarns 14 is provided, and these as

shown, are interlaced once in each weave repeat with the warp yarns 13

of the main yarn system. Each successive warp yarn is preferably advanced to right or left in the drawing by the space of one weft yarn. The warp

yarns 14 of the further layer provide extensive warp direction floats, in

place of the weft direction floats provided in the Fig. 1 embodiment.

As noted above, extensive yarns floats on either the warp or weft

direction can alter the drainage properties of the fabric, and thus provide for

desired marking on a prescribed pattern of a tissue web formed or dried on

the fabric. The distribution of knuckles and floats may be arranged in the

tissue contacting layer as desired to provide any suitable pattern on the

marked tissue, for example reticular, or conforming to a decorative image.

The interlacing of the warp yarns 5, 6 can be achieved by the warp

threads being drawn in special leno heddles which during weaving shift the

warp threads sideways, i.e. parallel to the weft threads. This leno heddle

motion for a warp thread takes place when the warp thread in the warp

thread system facing the paper web is positioned below a weft thread

interlacing with this warp thread. A fabric may contain layers or areas

which have been thus interlaced alongside or interlayered with

conventionally interwoven multiply fabrics.

Claims

1 . A tissue marking fabric comprising at least one weft yarn system and

at least two warp yarn systems, at least two of the warp yarn

systems being interlaced with each other, characterised in that

extensive yarn floats are provided on the tissue contacting face of

the fabric in a warp yarn system and/or a weft yarn system, the

floats being provided by the interlacing yarns.

2. A tissue marking fabric according to claim 1 , wherein two weft yarn

systems are provided extending in the cross-machine direction, two

separate warp yarn systems being also provided, one associated with

a lower weft yarn system and interwoven therewith, and the other

associated with an upper weft yarn system, each yarn of said other

systems being at least partially interwoven with the yarns of the

upper weft yarn system, and at least some of the warp yarns of the

second warp yarn system being passed below two or more of the

weft yarns of the lower weft yarn system to thereby create weft yarn

floats on the tissue contacting face of the fabric.

3. A tissue marking fabric according to claim 1 , wherein a single weft

yarn system is provided, and a first warp yarn system associated

therewith and interwoven with the weft yarns, a second warp yarn

system also being provided and comprising yarns which are not interwoven with the weft yarns, but which are interlaced with spaced

knuckles of the first warp system, to thereby produce extensive

floats in the second warp yarn system which are presented in the

tissue contacting face of the fabric.

4. A tissue marking fabric according to any preceding claim, wherein the

interlacings between the yarns of the first and second warp yarn

systems may involve alternate right and left twists given to the yarns

of the second warp yarn system.