GB752341A - Improvements in or relating to alkali cellulose xanthates - Google Patents

Abstract

752,341. Alkali cellulose xanthate. SOC. DE LA VISCOSE SUISSE. Jan. 6, 1954 [Jan. 16, 1953], No. 412/54. Class 2 (2). Substantially pure, stable alkali cellulose xanthate is produced by extruding viscose through spinnerets into a liquid precipitant for the xanthate, washing the xanthate filaments thus obtained with a volatile organic liquid which is at least partly miscible with water, and drying the filaments, first for a short period in a current of warm air and then at reduced pressure in the presence of a dehydrating agent. The precipitant is preferably maintained at below 5 ‹ C. and may be methanol, a solution of neutral salts in methanol or a saturated aqueous solution of a neutral salt, e.g. ammonium sulphate. The filaments are preferably cut into short staple sections before the final drying step. The organic liquid is preferably diethyl ether. The air drying is preferably effected at 30- 60‹ C. for at least 30 minutes, and the final drying at low pressure is preferably effected over phosphorus pentoxide. In the example, alkali cellulose produced from sulphite pulp and containing 30 per cent of alpha-cellulose and 15 per cent of caustic soda is xanthogenated, using 65 kg. of carbon bisulphide per 100 kg. of alpba-cellulose. The xanthate obtained is dissolved in dilute caustic soda solution to yield a viscose containing 7 per cent of alpha-cellulose having a DP value of 450 and 7 per cent of caustic soda, the molecular ratio of carbon bisulphide to glucose residues in the xanthate being 0,9. The viscose is spun into absolute methanol at - 5 ‹ C. to yield filaments of sodium cellulose xanthate. These are washed in diethyl ether, exposed to a warm dry air current at 60‹ C. for 30 minutes, and dried for 72 hours at 20‹ C. in vacuo over phosphorus pentoxide. The products of the invention remain completely water-soluble for at least one year when suitably stored, and may be used as adhesives and for dressing or finishing textiles by application to textiles in the form of aqueous or alkaline solutions and thereafter converting the xanthate into cellulose on the textile support.