Patent GB-616594-A (GB)
Title: Process for the production of stable, non-gelatinizing, solutions of cellulose
IPC: C08B1/00
Filed: 1946-09-17
Abstract: Stable non-gelatinising solutions of cellulose are obtained by degrading natural or regenerated cellulose in caustic soda solution of at least 20 per cent strength containing zinc oxide in solution, the operation taking place in the presence of oxidizing agents stable in strong caustic alkali solutions, and the dissolution of the cellulose being effected by dilution. Suitable oxidizing agents are hypochlorite, organic sulphochloramides such as sodium p-toluenesulphochloramide and sodium p-toluenesulphodichloramide, salts known as "persulphates," e.g. Na2S2O8.  Both natural and regenerated cellulose may be used as starting materials.  The alkali-zinc oxide solution is prepared as in Specification 616,421. The amount of oxidizing agent added may be from 2 per cent to 20 per cent of the weight of cellulose.  The amount of caustic soda in the solution after final dilution with water or dilute alkali to dissolve the cellulose should not exceed 10 per cent.  The solutions may be used for stiffening textiles, e.g. by impregnation with the cellulose solution and then with a precipitating solution containing sulphuric acid and sodium sulphate, or by mercerizing after impregnation. Printing effects may be obtained.  In an example, 7.5 kg. of short length viscose waste are introduced with stirring into a mixture of 750 g. sodium persulphate in 10 litres of water and 25 kg. of a solution containing 30 per cent NaOH and 10 per cent ZnO.  After allowing to cool, it is diluted with 56.75 kg. of 1 per cent caustic soda giving a thinly fluid solution.ALSO:Stable non-gelatinizing solutions of cellulose are obtained by degrading natural or regenerated cellulose in caustic soda solution of at least 20 per cent strength containing zinc oxide in solution, the operation taking place in the presence of oxidizing agents stable in strong caustic alkali solutions, and the dissolution of the cellulose being effected by dilution. Suitable oxidizing agents are hypochlorite, organic sulphochloramides such as sodium-p-toluene-sulpho - chloramide and sodium - p - toluene sulphodichloramide, salts known as "persulphates," e.g. Na2S2O8.  Both natural and regenerated cellulose may be used as starting materials.  The alkali-zinc oxide solution is prepared as in Specification 616,421.  The amount of oxidizing agent added may be from 2 per cent to 20 per cent of the weight of cellulose.  The amount of caustic soda in the solution after final dilution with water or dilute alkali to dissolve the cellulose should not exceed 10 per cent.  The solutions may be used for stiffening textiles, e.g. by impregnation with the cellulose solution and then with a precipitating solution containing sulphuric acid and sodium sulphate, or by mercerizing after impregnation.  Printing effects may be obtained.  In an example, 7.5 kg. of short length viscose waste are introduced with stirring into a mixture of 750 g. sodium persulphate in 10 litres of water and 25 kg. of a solution containing 30 per cent NaOH and 10 per cent ZnO.  After allowing to cool, it is diluted with 56.75 kg. of 1 per cent caustic soda giving a thinly fluid solution.