GB815304A - Process of producing artificial threads and like articles from viscose - Google Patents

Abstract

Regenerated cellulose filaments and like products consisting entirely of skin are made by extruding viscose containing 4-8 per cent of cellulose, 4-8 per cent of caustic soda, 30-50 per cent of carbon disulphide (based on the weight of the cellulose) and 0.2-4 per cent, preferably 0.5-2 per cent (based on the weight of the cellulose) of polyoxyalkylene glycol ethers of castor oil or of hydrogenated castor oil or of mixtures thereof, into an aqueous coagulating bath containing 10-25 per cent of sodium sulphate, 3-15 per cent of zinc sulphate (or at least 3 per cent of zinc sulphate and, in addition thereto, a water-soluble sulphate of a heavy metal other than zinc, the concentration of the sulphate of the metal other than zinc being such as to bring the total heavy metal sulphate content of the coagulating bath to not over 15 per cent, calculated as zinc sulphate) and sulphuric acid, the sulphuric acid content of the coagulating bath exceeding the slubbing point but being below the concentration at which neutralization of the caustic soda in the viscose is so rapid as to produce filaments consisting of skin and core. The ethers may contain 20-200 or more, preferably 30-100, ethylene oxide units per molecule of castor oil or hydrogenated castor oil. The ether may be added at any stage in the production of the viscose, and the salt test of the viscose at the time of spinning is preferably 6 or higher, particularly 8 or higher. In an example, a viscose containing 7 per cent of cellulose, 6 per cent of caustic soda, 41 per cent of carbon disulphide (based on cellulose) and 2 per cent of a polyoxyethylene glycol ether of castor oil (containing about 40 ethylene oxide units per molecule of castor oil) is spun at a sodium chloride salt test of 9 into a coagulating bath which is at about 60 DEG C. and contains 7.3 per cent of sulphuric acid, 8 per cent of zinc sulphate and 18 per cent of sodium sulphate. The yarn is thereafter conducted through a bath of water at about 95 DEG C. in which it is stretched about 82 per cent. Small proportions of the ethers may also be added to the spinning bath.