Improvements in viscose process and products produced thereby

摘要

To viscose containing cellulose of relatively uniform chain length and of 300 to 800 D.P. there is added at least 0.1 per cent of a copolymer of ethylene oxide and propylene oxide represented by the formula in which the average values of x and y are 6-106 and 19-28 respectively, and the viscose is spun into an acid saline regenerating bath containing at least 6 per cent, preferably 6-12 per cent, of a zinc salt, preferably zinc sulphate, or a chemically equivalent proportion of another salt, preferably a sulphate, having the same effect on filament formation as the zinc salt. Preferably, the spin bath contains 9-10 per cent of sulphuric acid and is at 45-70 DEG C., and the filaments are stretched from 70 to about 200 and even up to 1000 per cent in the bath. In addition to the copolymer, the viscose may contain a small proportion of an amine, such as dimethyl- or cyclohexyl-amine, or of dimethylformamide, or these compounds may be added to the spin bath. The cellulose and caustic soda contents of the viscose may be 4-13 and 5-13 per cent respectively and its salt index may be 6-20. In an example, viscose containing 7.5 per cent of cellulose, 6.5 per cent of sodium hydroxide, and 0.5 per cent of a copolymer in which x is 16 and y is 28, and having a sodium chloride index of 15, is spun into a coagulating bath at 58 DEG C. containing 9.5 per cent of sulphuric acid, 20 per cent of sodium sulphate, 9 per cent of zinc sulphate and 1 per cent of dimethylformamide, and the extruded filaments are stretched 250 per cent in the bath over a 200 inch path of travel. The filaments have high tensile strength and are suitable for use in the manufacture of tyre cord. Specification 735,481 is referred to.