GB595403A - Production of filaments from viscose having the capacity to crinkle - Google Patents

Abstract

Artificial filaments having the capacity to crinkle when treated with water are made by forming a viscose solution having from 7 to 13 per cent of cellulose and from 7 to 13 per cent of caustic soda with a cellulose to caustic soda ratio of about 1, i.e. between 0.8 and 1.2, extruding into an acid spinning bath to form coagulated and regenerated cellulose filaments and subjecting the filaments to stretching at a tension of more than 0.25 gram per denier and preferably at as high a tension as possible without injury to the filaments. The filaments may be dried without appreciable shrinkage and thereafter washed with water or with a solution of a swelling agent, e.g. a 50 per cent aqueous solution of potassium iodide to produce the crinkle. Preferably, the viscose used has a salt point of from 4.0 to 7.5. Filaments with potentiality to crinkle when washed with water may be preserved in the straight state without mechanical stress by taking them directly from the spinning machine and washing free from acid with a 45 per cent aqueous solution of ammonium acetate. Crinkled filaments may be obtained having a filament denier of 1 to 7 or even lower and a strength of more than 3 grams per denier and an elongation of about 20 per cent in the fibre itself. In examples: (1) viscose with a composition of 10 per cent each of cellulose and caustic soda, and a salt index of 5.8 is spun into a common spin bath, and the filaments are stretched under a tension of 200 grams for 200 deniers, collected in a centrifugal pot, skeined and placed in water, whereupon they become crinkled; (2) viscose having 9 per cent each of cellulose and caustic soda at a salt index of 5.5 is spun into an acid bath and the filaments drawn at a tension of 350 grams for 400 deniers, cut into staples and placed in water; and (3) viscose having 10 per cent cellulose and 9 per cent caustic soda and a salt index of 6 is spun into an acid bath and the filaments stretched at a tension of 190 grams for 200 deniers with progressively increasing tension while in the spin bath, skeined and washed.