GB793222A - The wet spinning of cellulose triesters - Google Patents

Abstract

Shaped articles having a basis of a cellulose ester of a monocarboxylic acid, having a degree of substitution of at least 2.7, and preferably 2.85 or more, are made by extruding through one or more shaping orifices a solution of the cellulose ester in a solvent consisting wholly or mainly of methylene chloride into a coagulant consisting essentially of water. The ester may be a propionate, butyrate, acetate-formate, acetate-propionate or acetate-butyrate of cellulose or, particularly, a cellulose triacetate. The solvent for the ester advantageously contains a small proportion of a secondary solvent, especially up to 20 per cent by weight, and preferably about 5-15 per cent by weight, of a lower aliphatic alcohol such as methanol, ethanol, n-propanol, isopropanol or isobutanol. The concentration of the cellulose ester in the solution may be about 15-30 and preferably 19-27 per cent. The coagulant may be at a temperature of 0-70 DEG C. and is preferably passed through the coagulating zone at such a rate that all the methylene chloride derived from the spinning solution will dissolve in it. In example, a solution of a cellulose triacetate in a 90/10 by weight methylene chloride/methanol mixture is spun into water at 20 DEG C. and the filaments formed are drawn through a column through which water is pumped in the same direction. After leaving the column the resulting yarn is taken up.