GB844024A - Improvements in or relating to artificial continuous filament yarns - Google Patents

Abstract

Continuous-filament yarn is made by spinning into a setting medium a solution of an organic cellulose derivative, combining the resulting filaments at a point near the spinneret with synthetic organic polymer filaments having an equilibrium moisture regain of less than 4,5% to form a combined filament bundle comprising 50-85% by weight of the synthetic polymer and 15-50% by weight of the cellulosic filaments, the ratio of the extended length of the cellulosic filaments to that of the synthetic polymer filaments being 0,97 to 1,15, and thereafter processing the combined filament bundle in a manner conventional for the cellulosic filaments. The synthetic polymer is preferably a polyamide, a polyethylene terephthalate, or an acrylonitrile polymer containing at least about 85% and preferably 100% by weight of polyacrylonitrile. A list of other synthetic organic polymers which may be used is given. The cellulosic filaments are preferably of regenerated cellulose (rayon) or of cellulose acetate. The "equilibrium moisture regain" is defined as the percentage of water contained in the polymer filaments, based on the dry filaments, when they are permitted to come to equilibrium with air at 65% humidity and 70 DEG F. after having been dried to a moisture content below the equilibrium level. The ratio of the extended length of the cellulosic filaments to that of the synthetic polymer filaments, i.e. the filament length ratio, is measured by determining the minimum elongation required to remove substantially all loops in the yarn. Some details of this measurement are given. The filaments of each component may be of any cross-section. In an example, viscose is extruded into a coagulating bath and the filament bundle thus formed is passed under a hook guide situated about 2 inches from the spinneret. A 20-filament yarn of polyethylene terephthalate, melt-spun and drawn until it has 3,02 times its original length and its denier is 30, is withdrawn from a spool situated near the spinneret and led under the same hook guide so that the two filament bundles are combined. The combined filament bundle is led for a distance of 24 inches through the bath, then round a roller guide and up to a rotating feed wheel. The tension on the yarn during spinning is low, so that the polyethylene terephthalate filaments are not appreciably stretched. The yarn is lead downwardly into a centirfugal spinning pot and the resulting cake is treated according to the conventional viscose process. The total denier of the rayon filaments in the final yarn is 10 and the filament length ratio is 0,98. Specification 578,079 is referred to.