Patent GB-723214-A (GB)
Title: Process for the production of artificial filaments and staple fibres of proteins
IPC: D01F4/00
Filed: 1951-06-26
Abstract: In the production of artificial protein filaments (which may subsequently be cut to form staple fibres) by the wet spinning of a solution of a water-insoluble globular protein, the protein, prior to the spinning operation, is treated with an aqueous solution of a tin salt, which salt becomes " fixed " in the protein, in the sense that it cannot be extracted therefrom with water.  The treatment of the protein with the tin salt may be effected prior to dissolving the protein in an aqueous medium to form the spinning solution and the treated protein may be washed or washed and dried prior to being dissolved.  The protein may be treated with tin salts such as stannous or stannic chloride or ammonium chloro-stannate in order to decrease the rate of viscosity increase on storage of spinning solutions prepared from the treated protein.  Other tin salts which may be used for treating the protein include acetates, formates and alkali metal salts of stannic acid.  The filaments spun from the treated protein, while in the spinning bath or thereafter, may be treated with a water-soluble aluminium salt and/or with a further quantity of a tin salt.  The protein, after treatment with the tin salt (and possibly also a water-soluble aluminium salt) may be treated before or after spinning with phosphoric acid or a phosphate such as mono-, di- or trisodium phosphate.  Alternatively the protein, after treatment with a tin or a tin and an aluminium salt, may be treated before or after spinning with an aqueous solution of a silicate such as sodium silicate.  In an example 3000 c.c. of an aqueous solution of 10 grams of SnCl2.2H2O is thoroughly mixed with 1000 gm. of lactic casein containing 10 per cent moisture and after 13 hours the mixture is dissolved in 200 c.c. of an aqueous solution of sodium hydroxide (density 1.33) diluted with 300 c.c. of water, de-aerated under vacuum and filtered.  The viscosity of the solution at 20 DEG  C. is found to increase much more slowly than that of an untreated casein solution of the same concentration.  In other examples lactic casein, zein, peanut and soya bean proteins, sulphuric acid treated casein and rennet casein are similarly treated with mixtures of stannous and stannic chlorides.  In a second set of examples the proteins treated with tin salts are washed until neutral, treated with aqueous solutions of disodium phosphate, sodium silicate, and sodium silicate and disodium phosphate respectively, again washed until neutral and then dissolved in aqueous sodium hydroxide solutions.  In a third set of examples lactic casein is treated as in first and second sets of examples but is dissolved in an aqueous solution containing sodium stannate as well as sodium hydroxide.  Potassium stannate may be used instead of sodium stannate.  The protein solutions containing a stannate increase in viscosity with keeping.  Spinning solutions prepared from the treated proteins may be spun into any of the known acid salt spinning baths. Preferably the filament bundles from each spinneret are stretched 10-100 per cent in the spinning bath or immediately after leaving the spinning bath, assembled to form a single roving and passed continuously with or without tension, through an aqueous anti-swelling solution of 200-250 grams sodium chloride and 20-50 grams of aluminium sulphate (17-18 per cent Al2O3 content) per litre, maintained at 25-40 DEG  C.  The roving is then passed through a preliminary aqueous hardening bath containing 150-200 grams aluminium sulphate, 25-80 grams urea and 130-150 grams sodium chloride per litre maintained at 25-60 DEG  C.  The roving is then stretched 100-300 per cent and cut into staple fibres, which are thereafter fully hardened in autoclaves through which is circulated an aqueous solution of 100-200 grams aluminium sulphate, 150-250 grams sodium chloride and 30-40 grams of 100 per cent formaldehyde per litre, initially at 20-35 DEG  C. and subsequently at 70-100 DEG  C.  One or more tin salts, e.g. stannous chloride, may be substituted for part of the aluminium sulphate in the preliminary hardening bath, but the filaments are preferably treated with tin salts after they have been fully hardened, e.g. with a 5-30 DEG  B<\>ae aqueous solution of stannic and/or stannous chloride for 1-3 hours at 20-40 DEG  C.  The filaments are then washed and may be treated with a 2-5 DEG  B<\>ae solution of mono- and disodium phosphate.  The filaments may thereafter be washed and treated with a solution of a silicate such as sodium silicate.ALSO:Water-insoluble globular proteins are treated with an aqueous solution of a tin salt, which salt becomes "fixed" in the protein, in the sense that it cannot be extracted therefrom with water.  The treated protein may be spun into filaments (see Group IV (a)).  The treatment of the protein with the tin salt may be effected prior to dissolving the protein in an aqueous medium and the treated protein may be washed or washed and dried prior to being dissolved. The protein may be treated with tin salts such as stannous or stannic chloride or ammonium chlorostannate in order to decrease the rate of viscosity increase on storage of solutions prepared from the treated protein.  Other tin salts which may be used for treating the protein include acetates, formates and alkali metal salts of stannic acid. The protein, after treatment with the tin salt (and possibly also a water-soluble aluminium salt) may be treated with phosphoric acid or a phosphate such as mono-, di- or trisodium phosphate. Alternatively the protein, after treatment with a tin or a tin and an aluminium salt, may be treated with an aqueous solution of a silicate such as sodium silicate.  In an example 3000 cc. of an aqueous solution of 10 gm. of SnCl22H2O is thoroughly mixed with 1000 gm. of lactic casein containing 10 per cent moisture and after 13 hours the mixture is dissolved in 200 cc. of an aqueous solution of sodium hydroxide (density 1.33) diluted with 300 cc. of water, deaerated under vacuum and filtered.  The viscosity of the solution at 20 DEG  C. is found to increase much more slowly than that of an untreated casein solution of the same concentration.  In other examples lactic caseins, zein, peanut and soya bean proteins, sulphuric acid-treated casein and rennet casein are similarly treated with mixtures of stannous and stannic chlorides.  In a second set of examples the proteins treated with tin salts are washed until neutral, treated with aqueous solutions of disodium phosphate, sodium silicate, and sodium silicate and disodium phosphate respectively, again washed until neutral and then dissolved in aqueous sodium hydroxide solution.  In a third set of examples lactic casein is treated as in the first and second sets of examples but is dissolved in an aqueous solution containing sodium stannate as well as sodium hydroxide. Potassium stannate may be used instead of sodium stannate.