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  Blended woven or knitted fabrics containing polyerethane elastic fibers and process for the production thereofUSPTO Application #: 20060030229Title: Blended woven or knitted fabrics containing polyerethane elastic fibers and process for the production thereof Abstract: A blended woven or knitted fabric which contains both highly fusible polyurethane elastic fibers exhibiting a retention of tenacity of 50% or above after the dry heat treatment at 150° C. for 45 s at 100% elongation and a melting point of 180° C. or below and at least one kind of non-elastic yarns and which is produced by fusing the polyurethane elasotomeric fibers to each other or the polyurethane elastic fibers to the non-elastic yarns at the crossover points by dry- or wet-heat setting; and a process for the production thereof. (end of abstract) Agent: Birch Stewart Kolasch & Birch - Falls Church, VA, US Inventors: Kunihiro Fukuoka, Kouji Nishio USPTO Applicaton #: 20060030229 - Class: 442197000 (USPTO) Related Patent Categories: Fabric (woven, Knitted, Or Nonwoven Textile Or Cloth, Etc.), Woven Fabric (i.e., Woven Strand Or Strip Material), Including Strand Which Is Of Specific Structural Definition, Strand Material Formed Of Individual Filaments Having Different Chemical Compositions The Patent Description & Claims data below is from USPTO Patent Application 20060030229. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to woven or knit fabrics containing polyurethane elastic filaments in combination with other fibers, and to a process for manufacturing such fabrics. More specifically, the invention relates to polyurethane elastic filament-containing blended woven or knit fabrics, including circular knit (e.g., plain, rib, purl) and other types of weft knit fabrics, warp knit fabrics (e.g., chain, denbigh, cord, atlas), and woven fabrics, which minimize the appearance of fabric defects such as deformation, yarn slippage and grinning from repeated stretching when articles made from such woven or knit fabrics are worn, fraying in which threads are lost from cut edges of the fabric, damage or defects of the type known as laddering or running that arise in the fabric structure, edge curling of the fabric, and the effect sometimes referred to as "slip-in" where just the elastic filaments pull away from a seam in an article that has been cut and sewn, causing the fabric to lose its stretch in places. The invention relates also to a process for manufacturing such fabrics. BACKGROUND ART [0002] Articles made from stretch fabrics such as polyurethane elastic filament-containing blended fabrics that have been weft knitted, warp knitted or woven are widely used on account of their high stretch, good recovery from extension, and good fit. However, when an article made by cutting and sewing a polyurethane elastic filament-containing blended fabric is repeatedly stretched, it deforms, causing the fabric to lose its uniformity and making it subject to problems such as deformation, yarn slippage, grinning, fraying, running and edge curling. In sewn areas, repeated extension also tends to cause polyurethane elastic filaments to pull away from the seams ("slip-in"). In an area of the fabric where such slip-in has occurred and elastic filaments have left from a seam, the loss of shrinkage force tends to give rise to places of uneven density in the fabric, which can render an item of apparel unfit for use. [0003] While these effects do occur even in woven and knit goods made with elastic filaments other than polyurethane elastic filaments, they are especially striking in fabrics containing high-stretch polyurethane elastic filaments. [0004] The following solutions have been proposed for these problems. [0005] (1) Suppress the shrinkage force of the polyurethane elastic filaments. [0006] (i) Avoid excessive extension of the polyurethane elastic filaments. [0007] (ii) Increase the woven and knit fabric treatment temperature to hold down the shrinkage force of the polyurethane elastic filaments. [0008] (iii) Select elastic filaments having a high heat settability. [0009] (2) Fuse the polyurethane elastic filaments to each other at crossover points by increasing the heat-setting temperature. [0010] (3) Prevent the above effects by using low-melting polyurethane elastic filaments and having them fuse at a low temperature. [0011] (4) Increase the stitch density during sewing to prevent the polyurethane elastic filaments from sliding and thus discourage slip-in from occurring. [0012] (5) If the polyurethane elastic filaments are used in the form of a covered yarn, give the yarn a high twist or a double-covered structure. The air entanglement of such a covered yarn with another yarn has also been proposed (see JP-A 4-11036). [0013] (6) Employ a weaving or knitting technique that is resistant to slip-in and yarn slippage (see JP-A 2002-69804 and JP-A 2002-13052). [0014] However, lowering the degree of extension of polyurethane elastic filaments as in (1)(i) above also lowers the stretch properties of the fabric and increases costs owing to the larger amount of polyurethane elastic filaments that is used as a result. Weakening the shrinkage force of the polyurethane elastic filaments by increasing the heat-setting temperature as in (1)(ii) above is undesirable because this changes the tactile qualities of the fibers with which the polyurethane elastic filaments are used and also lowers the colorfastness of the woven or knit fabric. In weft or warp knit fabrics where there are crossover points between the elastic filaments as in (2) above, problems such as edge curling and slip-in can be prevented by fusing the elastic filaments. However, because such fusion requires the fabric to be heat set at a high temperature, the tactile qualities of the fibers with which the polyurethane elastic filaments are used change and the colorfastness of the fabric decreases. Increasing the stitch density during sewing as in (4) above makes the sewn areas of the fabric thicker, as a result of which articles of apparel created from the fabric are less comfortable to wear and thus at odds with the demands of the market. [0015] If elastic filaments that fuse at a low temperature are used as in (3) above, these filaments can be fused at a low heat-setting temperature of 140 to 160.degree. C. However, when such filaments are used in combination with high-melting polyurethane elastic filaments, the latter do not set to a sufficient degree, as a result of which the fabric has a poor dimensional stability. On the other hand, if heat setting is carried out within a high temperature range at which the high-melting polyurethane elastic filaments can set properly, the elastic filaments which generally fuse at a low temperature will incur a large decline in strength, weakening the recovery of the fabric from extension. Also, methods such as (4) and (5) above which involve the use of special composite yarns or a special knitting technique undesirably limit the properties of the finished article. [0016] JP-A 2001-159052 describes a method for preventing yarn slippage by heat-treating at 200.degree. C. a woven or knit fabric made with two kinds of polyether ester elastic filament having different melting points. However, in terms of elastic recovery and strain, polyether ester elastic filaments have a performance inferior to that of polyurethane elastic filaments, and are thus unsatisfactory. [0017] It is therefore an object of the present invention to provide polyurethane elastic filament-containing woven or knit fabrics which are stable and not subject to the loss of elastic filaments and non-elastic yarns used therein from cut and sewn areas of the fabric, and which are thus resistant to yarn slippage, grinning, fraying, running, edge curling and slip-in. DISCLOSURE OF THE INVENTION [0018] As a result of extensive investigations, we have discovered that when a blended woven or knit fabric which contains highly fusible polyurethane elastic filaments typically obtained by melt-spinning a polymer synthesized from a prepolymer prepared by the reaction of a polyol with a diisocyanate, wherein preferably at least 50 wt % of the starting polyol is a polyether polyol, and which contains also non-elastic yarns is heat-set, heat fusion occurs at places where the polyurethane elastic filaments come into contact with the non-elastic yarns and at places where the polyurethane elastic filaments come into contact with each other, giving a fabric that is resistant to yarn slippage, grinning, fraying, running, edge curling and slip-in without any loss in tenacity. [0019] The present invention thus provides the following polyurethane elastic filament-containing blended woven or knit fabrics and processes for manufacturing such fabrics. [0020] [I] A blended woven or knit fabric comprising [0021] highly fusible polyurethane elastic filaments having at least 50% retention of tenacity after dry heat treatment at 150.degree. C. for 45 seconds at 100% extension and a melting point of 180.degree. C. or below and [0022] at least one kind of non-elastic yarn, [0023] said fabric being obtained by dry or wet heat setting so as to thermally fuse the highly fusible polyurethane elastic filaments to each other or to the non-elastic yarns, preferably to the non-elastic yarns, at crossover points therebetween. [0024] [II] The blended woven or knit fabric of [I] further comprising high-melting polyurethane elastic filaments having a melting point of 200.degree. C. or higher, [0025] said fabric being obtained by thermally fusing the highly fusible polyurethane elastic filaments with the high-melting polyurethane elastic filaments at crossover points therebetween. [0026] [III] A process for manufacturing a blended woven or knit fabric containing polyurethane elastic filament comprising the steps of [0027] forming a woven or knit fabric using highly fusible polyurethane elastic filaments having at least 50% retention of tenacity after dry heat treatment at 150.degree. C. for 45 seconds at 100% extension and a melting point of 180.degree. C. or below and at least one kind of non-elastic yarn and [0028] dry or wet heat setting the woven or knit fabric so as to thermally fuse the highly fusible polyurethane elastic filaments to each other or to the non-elastic yarns, preferably to the non-elastic yarns, at crossover points therebetween. [0029] [IV] The blended woven or knit fabric manufacturing process of [III] which additionally uses high-melting polyurethane elastic filaments having a melting point of 200.degree. C. or higher, and thermally fuses the highly fusible polyurethane elastic filaments with the high-melting polyurethane elastic filaments at crossover points therebetween. BRIEF DESCRIPTION OF THE DIAGRAMS [0030] FIG. 1 is a diagram showing an example of a chain knit fabric structure. [0031] FIG. 2 is a point diagram of the same chain knit fabric structure. [0032] FIG. 3 is a point diagram showing an example of a warp knit fabric structure. [0033] FIG. 4 is a point diagram showing another example of a warp knit fabric structure. [0034] FIG. 5 is a point diagram showing yet another example of a warp knit fabric structure. [0035] FIG. 6 is a point diagram showing a further example of a warp knit fabric structure. [0036] FIG. 7 is a point diagram showing a still further example of a warp knit fabric structure. [0037] FIG. 8 is a point diagram showing yet another example of a warp knit fabric structure. [0038] FIG. 9 is a point diagram showing a still further example of a warp knit fabric structure. [0039] FIG. 10 shows a warp knit fabric specimen for a tensile test. Continue reading... Full patent description for Blended woven or knitted fabrics containing polyerethane elastic fibers and process for the production thereof Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Blended woven or knitted fabrics containing polyerethane elastic fibers and process for the production thereof patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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