GB779805A - Process for the production of artificial threads and films from viscose - Google Patents

Abstract

Artificial threads and fibres are produced from viscose of gamma value not below 42 to which has been added shortly before extrusion 0.06 to 0.4, preferably 0.12, per cent by weight (based on the viscose) of a complex compound of the formula [Me(X)6]An, where Me represents Fe, Zn, Cr, Cd or Sn, X represents an alkyl or alkanol amine or aryl amine, and An represents Cl, SO4 or NO3, by extruding the viscose into an aqueous coagulating bath containing 40-65 g./l. of sulphuric acid and 30-50 g./l. of zinc sulphate, and stretching the threads or films so formed by 80-120 per cent in a hot aqueous bath containing 2-10 g./l. of sulphuric acid. The complex compound may be (1) <FORM:0779805/IV(a)/1> The viscose preferably contains 7-8 and 5-7 per cent of cellulose and caustic soda respectively. The coagulating bath is preferably at 45-70 DEG C. and preferably contains 160-260 g./l. of sodium sulphate. The withdrawal speed is preferably 40-60 m./min. and the length of travel in the bath at least 30 cm. In the second or stretch bath the products are preferably stretched by 95-100 per cent at a temperature over 90 DEG C. In an example, viscose prepared from alkali cellulose which has been xanthated with 42 per cent by weight of carbon bisulphide (based on cellulose) and which contains 7.3 and 5.5 per cent of cellulose and caustic soda respectively, is mixed, 5 hours before being spun, with 0.1 per cent by weight of complex compound (1) and spun at a gamma value of 45 into a bath containing 49 g./l. of sulphuric acid, 200 g./l. of sodium sulphate and 39 g./l. of zinc sulphate. The length of travel of the threads in the bath is 70 cm. and the threads are then stretched 100 per cent in a second bath containing 6 g./l. of sulphuric acid at 90 DEG C. The products of the invention have increased strength and elasticity.