LU86936A1 - ELASTIC WOVEN MATERIAL - Google Patents

Description

ELASTIC WOVEN MATERIAL

The present invention relates to a woven material which is made elastic for use in the manufacture of clothing. This type of fabric can for example be a strip of woven polyester yarn which is made elastic for use in the manufacture of belts for shorts, underpants or underwear.

In the past, elasticity was obtained by including latex chains during the weaving process. These chains could be covered or bare.

Latex as an elastic material has certain disadvantages. One drawback is the strong shrinkage of the fabric in which the latex is used. A second drawback is that the latex degrades during dry cleaning.

To overcome these difficulties, fabric strips have been made in which the elastic material is elastane instead of latex. The elastane used was that sold under the brand "LYCRA" by the firm Du Pont Company of Delaware, USA. Elastane does not shrink or degrade, or at least not as much as latex.

However, elastane has its own drawback, namely that it is very slippery. Thus, replacing the use of latex with the use of elastane was not a simple matter of replacing elastane with latex. This would have presented difficulties both in the manufacture of the fabric strip and in the finished garment.

The difficulty during manufacture would have been that one could not supply the loom with elastane in the same way as with latex. This is due to the fact that the elastane is marketed in the form of a knitted strip which is unraveled irregularly into individual threads. It must be compared to latex which is in the form of strips of agglomerated parallel pieces which can easily break. If the elastane which is irregularly untwisted was supplied to the loom in the same way as it is done with latex, the result would be the inclusion in the fabric of elastane chains under different tensions, leading to embossing and dilding. of 2 1 finished fabric.

The difficulty in the finished garment would have been that if the belt were extended, the elastane would initially extend with the fabric belt but would retract through the weaving while the latter would remain extended. The latex also undergoes this retraction, but to a lesser extent and deemed acceptable if undesirable.

The problem of the slippery surface of the elastane was solved by covering the elastane with an outer covering having a less slippery texture, and this method has been used for a few years now. As previously mentioned, the use of coated latex was already known.

Covering the elastane, if this overcomes the aforementioned difficulties in manufacturing and in the finished garment, has other disadvantages. First, the recovery process is a relatively specialized and expensive process. Second, the elastane when covered is of relatively large cross section. A large cross-section means that the fabric strip is thicker, producing a belt which can be undesirably large, particularly at the points where a double thickness occurs, for example at the point where the two ends of a belt overlap, or when the strip is folded back on itself. A large cross section also means that the strip is more easily damaged. There are two reasons for this. First, larger chains are more likely to be damaged during sewing, as a needle inserted through the band will likely penetrate the chain instead of being deflected between the chains as would happen with smaller chains. large diameter. Second, deterioration caused to an individual chain is more serious because there are relatively few chains per unit of bandwidth.

The object of the present invention is an improved elastic fabric.

According to one of its aspects, the invention provides a fabric which is made elastic by inclusion of elastane in the weaving, characterized in that the elastane which is used is bare instead of being covered, but that the slippery of the elastane area is limited by the use of a checkerboard for crossing so that the elastane intertwines with the weft threads of the fabric, thereby preventing or reducing retraction.

According to another of its aspects, the invention provides a fabric which is made elastic by inclusion in the weaving of an elastic material which may be latex, or elastane, or another material, characterized in that the fabric comprising the elastic material further comprises a flexible adhesive agent which is housed in the interstices or junctions between the fabric and the elastic material, thereby preventing or reducing the retraction.

3 The flexible adhesive agent can be added either before or after weaving. The addition of the flexible adhesive agent before weaving can be carried out during the stage where the tensioned warp threads are about to penetrate the healds of the loom. Since the warp threads are at this stage separated and under tension, effective application is achieved. The addition of the flexible adhesive agent after weaving can be conveniently carried out during a pre-shrinkage step which takes place before the use of the fabric, by adding the adhesive agent in liquid form to the wetting agent used in the fabric. '' pre-withdrawal stage.

According to another aspect, the invention provides a material which is made elastic by means of the two characteristics above used in combination, namely the inclusion of bare elastane in a crossing checkerboard so that the elastane s' interweaving with the weft threads of the fabric, and the inclusion of a flexible adhesive agent which is lodged in the interstices or the junctions between the fabric and the elastane.

According to another aspect of the invention, a method of weaving elastane is proposed, the elastane being supplied in naked knitted form, this method comprising in a first stage the unraveling of the knitted naked elastane to give individual threads of bare elastane under various tensions, then consisting in equalizing the tensions of the different strands in a second step before feeding the loom.

The invention also relates to a weaving machine comprising a loom and a roller drive mechanism for evenly tensioning the individual strands which feed the loom, characterized in that the mechanism is suitable for use when weaving bare elastane delivered in knitted form by adding another roller drive device which can operate at a speed lower than that of the aforementioned roller mechanism, whereby the knitted elastane can first be unraveled at the level of the additional roller mechanism then fed in the form of individual wires into the first roller mechanism mentioned.

The additional roller mechanism can be connected to the first roller mechanism via reducers.

The invention will now be described more particularly by way of example with reference to the accompanying drawings. In the drawings:

Figure 1 is a perspective view of part of a strip of fabric made elastic, indicating dimensions thereof, this fabric can be of any known type or according to the invention;

Figures 2, 3 and 4 are various views of fabric which has been made elastic in a known manner by inclusion of bare or covered latex or 4 of covered elastane;

Figures 5, 6 and 7 are views similar to Figures 2, 3 and 4 of fabric which has been made elastic according to the invention by inclusion of bare elastane;

Figure 8 is a cross-sectional view of a device for applying the flexible adhesive agent; and

Figure 9 is a side elevation of the roller drive mechanism with elastane also shown in the plan.

Referring to the drawings, Figure 1 shows part of a strip of fabric of width W. Part of the strip, of length "I" is shown in more detail in Figures 2 and 5.

Figure 2 is a so-called "chart paper diagram" illustrating the length "1" of a woven polyester tape made elastic in a conventional manner using iatex. The letter "X" in thin lines represents a polyester warp thread: overlying a weft thread in polyester (the weft threads are not shown), an empty space between two letters "X" in thin lines representing the polyester warp thread underlying the weft. Thus, we can see the design of the warp and the weft of polyester. A letter "X" in dark lines represents the elastic material, in this case latex, which is included in the weaving in the form of warp threads. It will be seen that there are three polyester warp threads between adjacent latex warp threads. A letter "X" in a circle represents a plush facing the fabric.

Figure 3 is another view of the strip of Figure 2, the strip shown extended under tension. This view is a side sectional elevation of the strip showing a side view of a single warp yarn 20 of latex and sectional views of the weft yarns 21. The polyester warp yarns have been omitted. It will be noted that the latex warp thread 20, which is much more resistant than polyester, extends flat and that the weft threads 21 extend alternately above and below the latex warp thread 20.

Figure 4 is a view similar to that of Figure 3, but the strip is no longer shown in extension. As the tension is released, the warp thread 20 in latex sees its diameter develop and, in this way, comes to wedge against the polyester weaving.

Figure 5 is a card stock paper diagram similar to that of Figure 2 but showing woven polyester made elastic using bare elastane according to the invention. Some differences between this chart paper diagram and the one in Figure 2 appear immediately. First, there are considerably more polyester warp threads, although the width W of the bands as the number of warp threads of the elastic material are the same. Thus, there are six polyester warp threads between adjacent elastane warp threads. Secondly, the elastane warp threads are offset from each other in the sense that, as can be seen by looking transversely at the strip, elastane warp threads are alternately over and under the weft yarn. The checkerboard for the specifically depicted crossing works very successfully, which was unexpected. We could indeed expect the weft threads to be sheared by elastane or to produce a fabric of insufficient elasticity because the elastane is wedged.

Figure 6 shows another view of the strip according to the invention mounted stretched under tension. This view is a side elevation in section of the strip (similar to that of FIG. 3) and represents a side view of 2 adjacent elastane warp threads, 30a and 30b, one behind the other, the threads of polyester warp involved having been omitted from the drawing, and showing sectional views of polyester weft yarn 31. It will be noted that the elastane warp yarns 30a and 30b are wavy while the latex warp yarns extend flat.

Figure 7 is a view similar to that of Figure 6, but the strip is no longer stretched. The tension being released, the warp threads 30a and 30b do not see much increase in their diameter as does the latex warp thread. However, due to the checkerboard for the crossing used, the elastane warp yarns 30a, 30b and the polyester weft yarns 31 intertwine. Figure 7 can be compared to Figure 4. It will be understood that the armor structure used prevents the elastane from shrinking.

Retraction can also be prevented by using a suitable flexible adhesive agent which is housed in the interstices or junctions between the elastane warp threads on the one hand, and the weft and polyester warp threads on the other hand. The flexible adhesive agent may be included in or added to any fabric which has an elastic agent in the weave, in order to prevent or reduce the retraction of the elastic agent. The flexible adhesive agent can be included in or added to a fabric which has been made elastic according to the invention, that is to say by incorporating bare elastane in a checkerboard for crossing so that the threads weft and elastane intertwine in which case the effect of the adhesive agent is to increase the resistance to the retraction which is always provided by interlacing. The adhesive agent can also be incorporated or added to a fabric which has been made elastic in a known manner by the inclusion of rubber as an elastic agent, in which case the effect of the adhesive agent is to reduce or eliminate the weak but undesirable present retraction. The flexible adhesive agent can also be used in other fabrics made elastic.

6 The flexible adhesive agent can be composed of an aqueous solution of a mixture of surfactants and polymeric materials.

Referring to Figure 8, it can be seen that the flexible adhesive agent can be applied before weaving. In Figure 8 is shown a roller device 35 which is mounted on the loom (not shown) between the tape breakers and the healds. The direction of movement of the warp threads and the direction of rotation of the roller 36 are indicated by arrows. The addition of the flexible adhesive agent at this stage, when the warp threads are separated and tensioned, allows a very effective application of the adhesive agent to the surface of each warp thread. The roller 36 is controlled from the weaving loom by means of a transmission (not shown) comprising a belt whose tension can be adjusted to vary the speed of the roller 36. The speed at which the roller 36 is moved is much lower as the running speed of the warp threads. The roller device 35 includes an adjustable squeegee 37 so that only a thin layer of flexible adhesive agent is present on the roller 36. The roller device 35 also applies a lubricant to facilitate weaving. The lubricant is a finely dispersed paraffin wax emulsion. The flexible adhesive agent and the lubricant are mixed in proportions of eight to one in an aqueous solution.

Alternatively, the flexible adhesive agent can be added after weaving. In this case, it is added as part of a single treatment step in which the fabric is immersed in a bath containing a liquid mixture of the flexible adhesive agent with: (a) a polyvinyl acetate resin at a concentration of 10 g per Being as a starch or starch agent, (b) a resin to stabilize the polyester yarn, (c) water to pre-shrink the fabric, after which the fabric is dried.

Figure 9 is a side view of the device used to feed bare elastane on a loom. The bare elastane is commercially available in the form of a knitted strip 40. When one of the ends of the strip is pulled from the side 40, it is unknitted into individual threads 41. As can be seen in the view in plan view of the end of the strip 40, the strip does not unravel uniformly across its width and, consequently, the individual threads 41 are variously stretched. The strip 40 passes through a first roller device 42 comprising two controlled rollers 42a, 42b, and a tensioning roller 42c, intended to tension the strip 40 in order to loosen it at or just after the first roller device 42. The individual strands 41 then pass through a second roller device 43 similar to the first, but driven at higher speed, the effect of which is to uniformly stretch the individual strands 41.

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The individual strands under uniform tension pass through the loom which is not shown.

The second roller device 43 is controlled from the loom in a known manner. The first roller device 42, which is the novel feature of the device, is actuated from the second roller device 43 by a transmission which includes a reduction gear (not shown). The speed ratio between the second and the first roller device is 9,125 / 1.

Claims (2)

8 1. Fabric made elastic by inclusion of elastane in the weaving, CHARACTERIZED IN THAT bare elastane is used and IN THAT the slippery nature of the bare surface of elastane is limited by the use of a checkerboard for crossing, such that elastane intersects with the weft threads of the fabric, thus preventing or reducing retraction. 2. Fabric made elastic by inclusion in the weaving of an elastic material, such as elastane, CHARACTERIZED IN THAT the fabric also comprises a flexible adhesive agent which is housed in the interstices and the junctions between the fabric and the elastic material , thereby preventing or reducing retraction.