GB849780A - Improved method for imparting a stretch nature to cellulose ester yarn or tow - Google Patents

Abstract

Permanent stretch properties are imparted to a cellulose ester, e.g. acetate (propionate or butyrate) or triacetate, yarn or tow by treating the yarn &c. to increase its elongation at break followed by passage, at elevated temperature (360 DEG -440 DEG F.) through an angular path about the edge of a blade member and under a tension (0,05-0,4 grms per denier) sufficient to elongate the yarn. The yarn is then cooled as rapidly as possible to a temperature at least 150 DEG F. below the temperature at which it passed about the edge. Latent stretch, i.e. curled deformations, may be developed by reheating the yarn, as by passage through an aqueous bath, steam or dry heat, to a temperature of 120 DEG -140 DEG F. for a few seconds in untensioned condition. The yarn (as a running length or a wound package) may be treated to increase its elongation at break by immersion or forced circulation for a period of 15 minutes to 16 hours with an aqueous solution of one or more non-oxidising inorganic acids, e.g. sulphuric and hydrochloric acids, or salts thereof with polyvalent metals, e.g. zinc, cupric, aluminium, stannic chloride and cadmium sulphate, or mixtures thereof : the solution may contain wetting and/or swelling agent such as ethylene glycol dimethyl ether and/or organic solvent for removal of antistatic agent. The liquid treatment may be followed by washing and/or rinsing in an acid-neutralising solution and drying. Specification 558,298 is referred to.