Patent GB-815303-A (GB)
Title: Process of producing artificial threads and like articles from viscose
IPC: C08B16/00
Filed: 1955-09-15
Abstract: Artificial threads and like products of regenerated cellulose consisting entirely of skin are made by extruding viscose into an aqueous spinning bath in the presence of a small proportion of a water-soluble polyoxyalkylene glycol ether of phenol, the bath containing 10-25 per cent, preferably 15-22 per cent, of sodium sulphate, 3-15 per cent, preferably 4-9 per cent, of zinc sulphate, and sulphuric acid, the concentration of the latter exceeding the slubbing point but being below the point at which neutralization of the caustic soda in the viscose is so rapid as to produce filaments consisting of skin and core.  The ether is present either in the viscose in a proportion of 0.2-4 per cent, preferably 0.5-2 per cent, based on the weight of cellulose in the viscose, or in the bath at a concentration of at least 0.04 per cent, preferably 0.1 per cent, or in both the viscose and the bath in proportions within the above ranges.  The coagulating bath may contain at least 3 per cent of zinc sulphate and, in addition thereto, a water-soluble sulphate of a heavy metal other than zinc, such as iron, manganese or nickel, in a concentration such as to bring the total heavy metal sulphate content of the bath to not over 15 per cent, calculated as zinc sulphate. The preferred ethers are the polyoxyethylene glycol ethers of phenol, containing 2-20 or more ethylene oxide units per molecule, particularly those containing 4-15 ethylene oxide units per molecule. The ether may be added at any stage in the production of the viscose, preferably after the cellulose xanthate has been dissolved in dilute aqueous caustic soda solution.  The temperature of the bath may be 25-80 DEG  C., preferably 45-70 DEG  C.  The maximum permissible sulphuric acid concentration in the bath is about 1.35 times the concentration of caustic soda in the viscose, and the acid concentration is preferably maintained at 1.2-1.3 times the caustic soda concentration.  In the production of filaments for tyre cord, the filaments are stretched after removal from the initial coagulating and regenerating bath and may then be passed through a final regenerating bath which may contain 1-5 per cent of sulphuric acid and 1.5 per cent of sodium sulphate, with or without a small proportion of zinc sulphate.  In an example, a polyoxyethylene glycol ether of phenol containing 4 ethylene oxide units per molecule of phenol is incorporated in a freshly prepared viscose containing 7 per cent of cellulose, 6 per cent of caustic soda, and (based on cellulose) 41 per cent of carbon bisulphide, the percentage of the ether (based on cellulose) being 2.  The viscose is allowed to ripen for 30 hours at 18 DEG  C. and spun into an aqueous coagulating and regenerating bath at 60 DEG  C. containing 7.6 per cent of sulphuric acid, 8.0 of zinc sulphate and 19 of sodium sulphate.  The filaments are then passed through water maintained at 95 DEG  C. while being stretched 82 per cent. Filaments produced according to the invention have improved abrasion resistance and flex-life and reduced cross-sectional swelling when wetted with water.  Specification 741,728 is referred to.