GB787486A - Method of forming all skin artificial threads and like articles from viscose - Google Patents

Abstract

Filaments, films and like products of regenerated cellulose consisting entirely of skin are produced by extruding viscose containing about 0.25-4 per cent, preferably 0.5-3 per cent, based on the weight of the cellulose, of an alkylene oxide adduct of ethylene diamine into an aqueous spinning bath containing about 10-25 per cent, preferably 15-22 per cent, of sodium sulphate, about 3-15 per cent of zinc sulphate and/or other heavy metal sulphate and sulphuric acid, the concentration of the latter exceeding the slubbing point but being below the concentration at which the products consist of skin and core. The alkylene oxide adduct contains at least about 28 up to 100, preferably 32-60, alkylene oxide units per molecule of ethylene diamine and is soluble in water and in dilute aqueous solutions of caustic alkalies and of acids. The coagulating bath may contain at least 0.02 per cent, preferably 0.05-0.15 per cent, of the ethylene oxide adduct. The temperature of the bath may be about 25-80 DEG C., preferably about 45-70 DEG C. When only the viscose contains the adduct, the percentage of acid in the bath should not exceed about 1.4 times the percentage of caustic soda in the viscose and is preferably about 1.2-1.35 times the latter. If the bath contains at least about 0.02 per cent, preferably about 0.05-0.15 per cent, of the adduct (the adduct being also present in the viscose in the proportions specified), the percentage of acid in the bath may be up to 1.6 times that of the caustic soda in the viscose. The products may be stretched after leaving the initial coagulating bath and then passed through a final regeneration bath containing about 1-5 per cent of sulphuric acid and about 1-5 per cent of sodium sulphate, with or without small proportions of zinc sulphate. In an example, 1 per cent (based on cellulose) of an adduct containing about 50 ethylene oxide units per molecule of ethylene diamine is added to viscose containing about 7 per cent of cellulose and 6 per cent of caustic soda and having a 41/100 carbon bisulphide/cellulose ratio. The viscose is allowed to ripen to 10.8 salt point and is spun into a bath containing 7.2 per cent of sulphuric acid, 20 of sodium sulphate and 8.4 of zinc sulphate, the temperature of the bath being 60 DEG C. The filaments are then stretched 82 per cent in water at 95 DEG C. and collected.