Patent GB-344474-A (GB)
Title: Improvements in the production of artificial filaments, films and like products fromviscose
IPC: D01F2/06
Filed: 1929-11-05
Abstract: Filaments, threads, ribbons, films, and other products are prepared from solutions of viscose by coagulating the viscose as a cellulose metal xanthate in a coagulating bath free from mineral acidity, and continuously treating the formed products with aqueous reagents capable of regenerating the cellulose. Coagulation of the viscose may be effected (1) with an organic coagulant such as ethyl alcohol or acetic, formic, lactic, or oxalic acid, or (2) with a metal salt capable of reacting with the viscose, such as an alkaline-earth or heavy metal salt, or (3) by dry methods, e.g. by spinning the viscose into heated air or into steam or benzene or toluene vapour; coagulation by a salting-out process, e.g. by spinning a sodium viscose into a concentrated solution of a sodium salt, is excluded. The conversion of the coagulated products into cellulose may be effected with strong aqueous solutions of mineral acids or of acid esters thereof or of organo-mineral acids, (cf. Specifications 335,894 and 338,989, [both in Class 2 (ii), Cellulose &c.]), suitable reagents being aqueous sulphuric acid of 45-85 per cent strength or more, hydrochloric acid of 20-40 per cent strength, nitric acid of 50-80 per cent strength or more, phosphoric acid of 60 per cent strength or more, or aqueous solutions of any of the following organo-mineral acids, viz. methyl sulphonic acid, ethylene sulphonic acid, propyl disulphonic acids, sulphoacetic or sulphosuccinic acid, ethanol sulphonic acid, benzyl sulphonic acid, mono-, di-, and poly-sulphonic acids of benzene, phenol, naphthalene and naphthol, sulphosalicylic acid, and sulphophthalic acid.  Conversion may also be effected with aqueous salt solutions or other aqueous reagents known to be capable of effecting coagulation and conversion. Alcohols such as glycerine, sugars such as glucose, or sulphonated oils may be added to the regenerating or the coagulating baths.  The products may be stretched during or subsequent to their production, preferably after coagulation and during or after conversion.  The process may be effected so that products containing white or coloured insoluble metal salts are obtained, e.g. by coagulating in barium chloride solution and regenerating with sulphuric acid; the formation of the insoluble salt may also be effected after regeneration.  In the examples, (1) viscose is spun into glacial acetic or 80-100 per cent formic acid at atmospheric temperature, and the filaments are carried round a feed roller, rotating at a peripheral speed equal to or greater than the speed of extrusion, into a bath of aqueous benzenesulphonic acid at atmospheric temperature; the filaments are carried round another roller rotating at the same speed as the first roller, or at a higher speed, and then washed; (2) spinning is carried out as in example 1, except that conversion is effected in an aqueous sulphuric acid bath of 55-75 per cent strength at 0-8 DEG C.; (3) viscose is spun into a solution of barium chloride and the filaments are carried, with or without stretching, into an aqueous sulphuric acid bath of low or high strength.