GB397137A - Improvements in yarn manufacture - Google Patents

Abstract

Yarns, particularly yarns of cellulose acetate or other organic derivatives of cellulose, having the appearance of spun yarn, that is yarn made from staple fibre, are produced by subjecting a bundle of filaments in a softened state to an operation such as stretching, whereby individual filaments are broken. As described, the yarn is stretched, subsequently to manufacture and with or without previous twisting, to such a degree that the main filament bundle does not break and, to ensure that as many ends as possible are broken, it is desirable to stretch to such an extent that a reduction in denier takes place: for example, threads of acetone-soluble cellulose acetate may be softened in 40-50 per cent dioxane, or an equivalent concentration of diacetone alcohol, ethyl lactate, glycol monoacetate, methyl glycol monoacetate or the like and stretched to 300-500 per cent. The stretching may be effected by two or more rollers rotating at different speeds and may take place while the yarn is in hank form, or while it is travelling, for example, from a yarn package to a winding-device, or from a spinning-machine to a winding-device, or filaments in warp formation may be stretched and a number of bundles, for example, five to ten or more, may be associated continuously with the stretching and twisted, or stretching may take place during the manufacture of the filaments. In wet spinning the filaments may be stretched and broken in the coagulating bath, suitable baths for producing filament bundles of low denier being described in Specifications 340,324, 340,325, 340,326, 340,436, 340,437, 343,062, 371,360, 375,423, and 380,819. The yarn may be treated to lay the projecting ends and subjected to a gassing operation. Preferably the final twisting is effected in the presence of a softening-agent, for example, by means of a Topham box, whereby a more crinkled yarn is obtained. The yarn may be doubled with any other yarn and with one or more broken filament yarns. The basic yarn may be of high, medium or low lustre. Any after treatment to modify the appearance or properties of the yarn may be applied, for example the yarns may be treated with shrinking-agents as described in Specifications 380,504, 380,505, and 389,823. The yarns may be introduced into the warp or weft or both of woven fabrics to produce the appearance of a fabric composed of staple fibre yarns, or to produce pattern effects, and may be used as effect material or the sole or principal constituent of knitted fabrics.