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.

Description

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, ...

AI Technical Summary

Benefits of technology

[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.

Problems solved by technology

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.

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.

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.

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° 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.

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.

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