GB1051472A - - Google Patents

Abstract

1,051,472. Regenerated cellulose filaments. FMC CORPORATION. Feb. 6, 1964 [Feb. 26, 1963], No. 5106/64. Heading B5B. Regenerated cellulose filaments or fibres are made by extruding viscose containing an amino viscose additive that reacts with sulphur and zinc to form a water-insoluble and alkalineinsoluble amino-sulphur-zinc compound into a spinning bath containing sulphuric acid, sodium sulphate and at least 0À02% by weight zinc sulphate (ZnSO 4 ), and subjecting the filaments or fibres to a dilute acid solution, especially a sulphuric acid solution, before drying to dissolve and remove from the filaments or fibres the omino-sulphur-zinc compound. The additive may be a monoamine, e.g. dimethyl-amine (forming zinc dimethyl dithiocarbamate) or diethylamine, diamines, e.g. ethylene diamine, or other polyamines, e.g. diethylene triamine, and may be used in proportions of 1-4% by weight, based on the cellulose, either alone or in combination with other viscose additives, e.g. condensation products of ethylene oxide and phenol and polyoxyethylene glycols. Preferably, the viscose used contains 4-9% cellulose, 5-10% caustic soda and 30-38% carbon disulphide, based on the cellulose, and is spun at a sodium chloride salt point of 2-17, especially 7-12, into a bath containing 5-10% by weight sulphuric acid, 9-20% anhydrous sodium sulphate and 0À02-9%, especially 2À5-7%, anhydrous zinc sulphate, and at a temperature of 10-40‹ C. The fibres formed may be withdrawn from the spinning bath and stretched to a stretch ratio of 1À8 to 2À6, preferably 2À25 to 2À6, while passing through a hot dilute cascade acid bath containing about 3% by weight sulphuric acid, 5% anhydrous sodium sulphate and 1À5% anhydrous zinc sulphate and at 85-100‹ C. using a spinning speed of 20-40 metres per min. The stretched fibres may then be cut into staple fibre lengths, and before drying and preferably immediately after cutting, treated with dilute acid under conditions such as to dissolve any reaction product or complex of the amino viscose additive and the sulphur and zinc present in the spinning operation. Suitably a 0À2 to 1À4% by weight sulphuric acid solution at a temperature of 96‹ C. may be used the treatment time being 15 minutes. Hydrochloric acid, and other inorganic and organic acids may replace the sulphuric acid. The fibres are then drained, washed, bleached, desulphurized, and dried in conventional manner. Such fibres are relatively non-fibrillatable, have a wet modulus of at least 10, preferably between 10 and 20, a water flow number of less than 25, and filaments or fibres of 1À5 denier and 39À7 mm. length have a card load factor of less than 3À25. Fibres so made resemble cotton in wet modulus, shrinkage characteristics and ultimate elongation in the wet and conditional states, but resemble conventional viscose rayon fibres with respect to lustre, softness and hand.