GB796384A - Production of articles of cellulose triesters by wet spinning - Google Patents

Abstract

Shaped articles having a basis of a monocarboxylic acid ester of cellulose of a degree of substitution of at least 2.7, preferably 2.85 or more, are made by extruding a solution of the cellulose ester in an organic solvent through one or more shaping orifices into a coagulant consisting essentially of water and an organic ester which will form with water a homogeneous mixture containing at least 0.5 per cent of the ester at a temperature between 0 DEG and 100 DEG C. The cellulose ester may be a propionate, butyrate, acetate formate, acetate pripionate, acetate butyrate, or particularly a cellulose triacetate of acetyl value (as acetic acid) above 58.8 and preferably about 61.0 per cent or higher. The solvent for the cellulose ester may be acetic acid, acetone, ethylene chlorohydrin, dimethyl-sulphoxide or dimethyl-formamide. Chlorinated hydrocarbon, e.g. methylene chloride, ethylene chloride or chloroform, either alone or in admixture with a small proportion of an auxiliary solvent, are preferred, particularly methylene chloride, either alone or in a mixture containing also up to about 20 per cent by weight of a lower aliphatic alcohol such as methanol, ethanol, n-propanol, isopropanol or a butanol. The organic ester present in the coagulant is preferably a lower aliphatic ester, e.g. ethyl acetate, isopropyl acetate, isobutyl acetate or secondary butyl acetate, or ethylene glycol or diethylene glycol diacetate. Ether esters may also be used, especially 2-methoxyethyl acetate, 2 - ethoxyethyl acetate, 2 - (2 - methoxyethoxy)-ethyl acetate and 2-(2-ethoxyethoxy)-ethyl acetate. The proportion of organic ester in the coagulant may be 0.5-25 per cent by weight and the temperature of the coagulant may be between 0 DEG and 100 DEG C. In an example, a solution of cellulose acetate of acetyl value 61.2 per cent (as acetic acid) in a 90/10 by weight methylene chloride/methanol solution is spun into an aqueous solution of 2-methoxyethyl acetate of 4.6 per cent by weight concentration at 24 DEG C. contained in an open trough. The filaments are drawn through the trough for a distance of 90 cm. and withdrawn as a yarn at a rate of 50 metres per minute, washed with water and dried.