GB372264A - Improvements relating to the manufacture of fibres, ribbons, films or the like from viscose - Google Patents

Abstract

Cellulose xanthates, processes for making filaments and films from; alkali cellulose.--Viscose of high concentration, e.g. 10 per cent or more, and of low viscosity suitable for spinning into threads, ribbons, films, &c., is prepared by treating cellulose with alkali of more than 20 per cent strength, and, after pressing, disintegrating the alkali cellulose at a raised temperature of 25 or 30 DEG C. or higher. The alkali cellulose may be sulphided directly or after ripening. Further to reduce viscosity, oxidizing agents may be added during the mercerizing, xanthating or dissolving steps; and the cellulose is preferably dried, e.g. at a temperature up to 100 DEG C. or higher. The viscose is spun into acid salt baths; cold baths yield dull and hot baths glossy threads. Stretch is applied to the threads. In an example, cellulose mercerized in 27 per cent caustic soda is pressed to 3 times its initial weight, disintegrated for 4\ba1/2\be hours at 28 DEG C., allowed to ripen for 24 hours, and xanthated with 32 per cent by weight of carbon disulphide; the xanthate is dissolved to form a solution having a cellulose content of 16 per cent and a sodium hydroxide content of 9 per cent, and is spun into a bath containing 13,5 per cent sulphuric acid and 30 per cent sodium sulphate, lustrous threads being obtained with a spinning temperature of 50 DEG C. or dull threads at 18-20 DEG C.