GB464050A - Improvements in the manufacture of artificial filaments, yarns, ribbons and like materials - Google Patents

Abstract

The extensibility of artificial filaments, threads, yarns, and like materials having a basis of an organic derivative of cellulose is improved by treating them with a medium comprising a latent solvent dissolved in an inert diluent and having a small shrinking power, and then increasing the concentration of the latent solvent on the materials by removing at least part of the diluent, these operations being effected in the absence of tension sufficient to stretch the materials. Shrinkage may be allowed to take place. The diluent may be removed by preferential evaporation if it is more volatile than the latent solvent, or the materials carrying the relatively dilute solution of latent solvent may be treated with a bath which is a solvent for the diluent. Methylene and ethylene dichlorides may be used as latent solvents. As diluents, amylene, pentane, isopentane, tetramethyl methane, ethyl chloride, isopropyl chloride, diethyl ether, and methyl ethyl ether, may be used. Treatment may occur at low temperature if desired. The materials may be treated in hank, bobbin, or other package form, or while travelling, e.g. from dry or wet spinning apparatus to winding or twisting devices, or while in parallel formation. The process may be applied to materials which have been stretched. In an example, cellulose acetate yarns are led in warp formation through a bath of methylene chloride in ethyl chloride at 8 DEG C. The issuing yarns are led through a warm chamber in which the concentration of methylene chloride on the materials is increased by evaporation of ethyl chloride, and the materials are allowed to shrink. They are subsequently washed. Benzene or other hydrocarbon may be used as washing liquid. In another example, bobbins of loosely wound cellulose acetate yarn are immersed in a solution of methylene chloride in methyl ethyl ether. Warm air is blown through the bobbins to increase the concentration of the methylene chloride. The bobbins are washed with benzene. Materials of other cellulose esters or ethers may be similarly treated. Specification 389,823 is referred to.