NZ201252A

NZ201252A - Woven fabric with stretched and split yarns

Info

Publication number: NZ201252A
Application number: NZ201252A
Authority: NZ
Inventors: W H Tough
Original assignee: Scott & Fyfe Ltd
Priority date: 1981-07-14
Filing date: 1982-07-13
Publication date: 1985-07-12
Also published as: IE821672L; EP0070176A2; AU554812B2; FI822488L; IE52997B1; FI822488A0; EP0070176A3; AU8590582A; DK313282A

Description

<div class="application article clearfix" id="description"> 201252 —IBillHiliHiiH LI I 1 Prior sty Dat«{s): . Jr.~.J'. f! Complete Specification Fftid: l£Z-7.'f? C'acs: "&&}"&!?/?& ,\ .. PeibHcation Data: i fl I. JULl98!f L -O. Journal. No: I ?.l1...... 13JUIJ982 Patents Form No.5 NEW ZEALAND PATENTS ACT 19 53 COMPLETE SPECIFICATION "STRETCHED FABRIC MATERIAL" -I-WE SCOTT & FYFE LIMITED a British company, of Scotscraig Works, Tayport, Fife, Scotland, hereby declare the invention, for which i/we pray that a patent may be granted to irte-/us, ,and the method by which it is to be performed, to be particularly described in and by the following statement:- -1- (followed by pa;e | A.) 201252 -lA- The present invention relates to woven fabric material and particularly fabric material including longitudinally extending yarns of nylon, polyester, polypropylene, 5 polyethylene or other stretchable fabric materials. According to one aspect of the present invention, there is provided a method of treating woven fabric material which comprises stretchable warp or weft yarns, the treatment comprising the steps of stretching the fabric 10 to stretch said stretchable warp or weft yarns and simultaneously to split the yarns which extend transversely to the stretchable yarns, said splitting being continuous or intermittent along the length of the said transversely 201252 -2- extending yams, and setting the stretchable yam in the stretched condition to obtain a stretched fabric material having substantially increased area. The yarns may be stretched cold or may be heated 5 to their softening point prior to stretching. Preferably, the stretchable yam comprises synthetic resinous plastics yam. The stretched yams can be stretched to at least 30% of the original length and preferably to at 10 least twice the original length. According to another aspect of the present invention there is provided a method of manufacturing a fabric material comprising the steps of forming a woven base fabric of warp and weft yams, said warp 15 yams comprising stretchable yams while said weft yams include longitudinally extending zones of weakness, stretching the base fabric to stretch said stretchable warp yams, said warp stretching serving to split said weft yams into spaced strips, and setting the stretch-20 able warp yams in the stretched condition, to obtain a stretched fabric material having substantially increased area. N.Z. PATENT Or -8 AUG 1984 • c r* n \ t * i -3- 201252 Methods in accordance with the present invention give advantages over a standard woven material, namely:- 1. An increase in the area of fabric for a given 5 quantity of material. 2. A reduction in the weight of the stretched warp or weft yarn. 3. Greater strength of fabric (in grammes/dtex) in the stretched direction. 10 A. An increase in width in the weft yarn may be achieved, resulting in an increase in cover in the fabric for a given quantity of yarn. 5. A bond between the warp and weft elements of the fabric may be achieved to a variable degree. 15 According to a further aspect of the present invention there is provided a woven fabric material comprising warp yarns and weft yarns, the weft yarns being intermittently split arri the intermittently split portions of the weft , yarns being separated into a plurality of strips having gaps there-between 20 as a result of stretching the warp yarns of the woven fabric material and as result of the woven fabric material being set in the stretched ccrdition. An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings in which: v Fig. 1 shows a base fabric used in this embodiment 25,of the present invention, and Z, J' Fig. 2 shows the base fabric of Fig. 1 treated in /' accordance with the present invention. 201252 -4- Referring to Figs. 1 and 2, base fabric material 1 comprises a woven construction of warp yarns 2 and weft yarns 3, which yarns 2, 3 are formed from flat polypropylene tape. The warp is a 111 tex tape produced 5 with a stretch orientation ratio of 6:1 for example, while the weft tape 3 is a 111 tex tape with a stretch orientation ratio of 7 to 1 and which has been produced with localised weakened areas 4 running in the longitudinal directions by means of fibrillation, embossing or other .10 methods. Thirty-nine threads per 10 cms can be provided in the warp direction and thirty-nine threads per 10 cms in the weft direction. Fig. 1 shows the fabric in the initial unstretched condition. The basic fabric 1 is now tensioned and heated to approximately 160°C at which 15 temperature the polypropylene yarns become softened. With the temperature controlled at the desired value of 160°C approximately, the fabric 1 is stretched in the warp direction (see arrow X in Fig. 2) to twice its original length. It is important to control the fabric temperature 20 within particular limits e.g. + 2°C for satisfactory results and the particular temperature selected will depend on the material of the yarn and other factors, such as the type of yarn bond desired. The warp yarn 2 experiences a weight reduction from 111 tex to 56 tex. 25 However, due to the increased orientation of the warp yarn 2, the tenacity of the yarn, as expressed in gms/dtex, will be increased and the extension of the yarn at breaking load will be reduced. The weft yarn 3 will not be n r\ u 1 252 -5- stretched longitudinally. However, due to the appropriate temperature applied to the fabric 1 and the tension and stretching which occurs in the process, the warp and weft yarns 2, 3 in the fabric will bond together at their 5 intersections 5. The degree of bonding may be adjusted by varying the conditions of temperature, tension and stretch. During the heating and stretching in the warp direction X and because of the bond achieved at the intersections 5 of warp and weft yarns 2, 3, the weft 10 tape 3 will be extended in its crosswise direction. Also because it has been weakened in the longitudinally extending direction it will tend to split along these weak zones or points 4 continuously or intermittently (depending on degree and form of weakening) into strips 15 6, which strips 6 will be pulled apart (see Fig. 2) thus retaining to a degree the effective cover of the weft tapes 3 despite their now being situated in the fabric at 19^ threads per 10 cms instead of the original 39 threads per 10 cms. As can be seen, the individual gaps 20 7 in the stretched fabric are smaller than would be the ^ case if the weft yarn did not split: this gives more ..... - effective cover. If the weft tapes are not weakened J I longitudinally their width will be extended by the t I I ej* f of disturbing of the molecular structure during the heat and Io > I '~j25 stretch process resulting in a possible reduction in CO j i '' , j tensile strength. If however the longitudinally weakened i j » I weft tape splits into a series of narrow strips 6 during the heat and stretch process the molecular orientation is •> : i -6- 201252 not disturbed and the tensile strength is maintained. Ultimately, on cooling the fabric, a permanent bond is achieved at the warp/weft intersections 5 resulting in a high degree of fabric stability with a satisfactory 5 retention of cover and strength. The advantages to be gained from producing the fabric in this form can be listed as follows 1. For every one square metre produced on the loom (i.e. as in Fig. l), two square metres of finished fabric 10 will result (Fig. 2) 2. If fabric can be produced with a resultant warp tex of 56 from an initial warp tex of 111, then this will result in a cheaper yarn cost per kilo in the fabric, as it is normal for the lower tex yarns to be more 15 expensive per kilo than the higher tex yarns 3. The resultant strength of the fabric in grammes/dtex in the warp direction will be greater after stretching than that of the fabric in the unstretched condition (Fig. 1) The resultant strength of the fabric 1 in the weft direction in grammes/dtex is maintained despite crosswise extension of the weft tapes 3. It will be appreciated that a base fabric 1 containing tapes (2, 3) of yarns of other synthetic or '{ 25 natural materials of differing construction, width, orientation,ratio, polymer or fibre base and situated in the base fabric with different settings of tapes or yarns per 10 cm, provided the tapes or yarns used can be extended if necessary by the percentage required under the selected conditions of temperature and direction of base fabric stretch. It will also be appreciated that in this embodiment the stretch may be applied to the base fabric in the longitudinal direction, or in both the longitudinal and transverse directions in varying degrees from 1% upwards. One commercial end use for the fabric described in this embodiment would be as a material for packing purposes, particularly for production of bags and sacks where good cover, strength and stability of the fabric is desirable at a low cost. In a modification, weft yarn for example in the form of tapes may be used which do not have the longitudinally extending weakened zones. .bmjgw84 </div>

Claims

<div class="application article clearfix printTableText" id="claims"> 201252 -8- WHAT WE CLAIM IS:

1. A method of treating woven fabric material which comprises stretchable warp or weft yarns, the treatment comprising the steps of stretching the fabric to stretch 5 said stretchable warp or weft yarns and simultaneously to split the yarns which extend transversely to the stretchable yarns, said splitting being continuous or intermittent along the length of the said transversely extending yarns, and setting the stretchable yarn in the ID stretched condition to obtain a stretched fabric material having substantially increased area.

2. A method of manufacturing a fabric material comprising the steps of forming a woven base fabric of warp and weft yarns, said warp yarns comprising stretchable yarns 15 while said weft yarns include longitudinally extending zones of weakness, stretching the base fabric to stretch said stretchable warp yarns, said warp stretching serving to split said weft yarns into spaced strips, and setting the stretchable warp yarns in the stretched condition, to 20 obtain a stretched fabric material having substantially increased area.

3. A method as claimed in Claim 1 or Claim 2, wherein the stretchable yarn comprises synthetic resinous plastics yarn. P- if WVl o 1 ..s r C- O I C- -9-

4. A method as claimed in Claim 2, wherein the weft yarn comprises synthetic resinous plastics yarn, said longitudinally extending zones of weakness being provided by yarn fibrillation or embossing. 5

5. A method of treating a fabric material wovenfrom tapes of synthetic resinous plastics material, the treatment comprising the steps of heating the fabric to a raised temperature at which the synthetic resinous plastics material will soften, stretching the fabric 10 longitudinally whilst at the raised temperature to extend the warp tapes longitudinally while simultaneously producing longitudinally extending splits in the weft tapes due to a lateral extension.of the weft tapes, and cooling the stretched fabric material while the warp 15 tapes are longitudinally extended to produce a dimension-ally stable fabric material having gaps between strips formed in the weft tapes by splitting thereof and a substantially greater surface area than the fabric material immediately after weaving. —2JT S "l

6. A method as claimed in any one of the preceding claims, wherein the stretchable yarn is stretched and ~ !'set with a length increase of at least 30% of the ^original length. vi

7. A method as claimed in Claim 6, wherein said length 25 increase is at least equal to the original length. 201253 -10-

8. A method according to any one of the preceding claims wherein the warp yarns or tapes are bonded to the weft yarns or tapes.

9. A method of making a stretched fabric material substantially as hereinbefore described with reference to the accompanying drawings.

10. Fabric material made by the method of any one of the preceding claims.

11. A woven fabric material comprising warp yarns and weft yarns, the weft yarns being intermittently split and the intermittently split portions,of the weft yarijs being separated into a plurality of strips . having gaps there-between as a result of stretching the warp yarns of the woven fabric material and as a result of the woven fabric material being set in the stretched condition.

12. A woven fabric material according to Claim 11 wherein the warp and weft yarns are bonded together at their intersections.

13. Fabric material substantially as hereinbefore described with reference to and as illustrated in Figure 2 of the accompanying drawings. by their Attorneys PAT.nwTKV cnw t riopv </div>