Patent GB-671383-A (GB)
Title: Improvements in and relating to the production of cellulose compounds
IPC: D01F11/02
Filed: 1949-03-30
Abstract: Water-insoluble, alkali-soluble and acidsoluble cellulosic material is produced by impregnating cellulose with an aqueous solution containing at least 20 and preferably at least 24 per cent by weight of sulphuric acid, at least 15 per cent of cyanamide and more than 0.5 and less than 8 per cent of free orthophosphoric acid or an equivalent concentration of a water-soluble orthophosphate, drying the impregnated cellulose and baking it at at least 110 DEG  C. and preferably at at least 140 DEG  C. A sulphate of an alkali metal or of ammonia is preferably added to the impregnating solution.  The baked material may be washed with a mixture of 30 per cent by volume of alcohol and 70 per cent by volume of water or with a concentrated aqueous solution of sodium chloride.  The cellulose material employed is preferably regenerated cellulose, e.g. viscose rayon filaments, which may be in the form of undried rayon yarn produced by washing rayon cake, or an undried tow of continuous filaments of rayon produced by the viscose or cuprammonium processes or rayon staple obtained by cutting an undried tow of continuous filaments.  The products are soluble in a 0.17 per cent aqueous solution of sodium carbonate at 90 DEG  C. and soluble in a boiling 0.5 per cent formic acid or boiling 0.01 per cent hydrochloric acid solution.  In an example a washed undried regenerated cellulose yarn is impregnated for 2-3 minutes with an aqueous solution consisting of 13 c.c. of 15 N sulphuric acid, 12 grams of ammonium sulphate, 0.5 gram of ammonium dihydrogen phosphate and 30 c.c. of 30-35 per cent cyanamide solution.  The impregnated yarn is hydroextracted, dried at about 60 DEG  C., baked for 2 1/2 minutes at 160 DEG  C., and washed in a solution of 30-40 per cent by volume of alcohol in water.  The products of the invention are said to be fire-resistant and when in the form of yarns may be used as carrier yarns or core yarns in the production of effect threads or fabrics.  Specifications 634,690 and 647,321 are referred to.ALSO:Cellulose textile material particularly regenerated cellulose yarn in the undried state, is impregnated with an aqueous solution containing at least 20 and preferably at least 24 per cent by weight of sulphuric acid, at least 15 per cent of cyanamide and more than 0.5 and less than 8 per cent of free orthophosphoric acid or an equivalent concentration of a water-soluble orthophosphate, and the impregnated material is dried and baked at at least 110 DEG  C. and preferably at at least 140 DEG C.  The product is insoluble in water but soluble in dilute solutions of alkalies or of acids.  A sulphate of an alkali metal or of ammonia is preferably added to the impregnating solution.  The baked material may be washed with a mixture of 30 per cent by volume of alcohol and 70 per cent by volume of water or with a concentrated aqueous solution of sodium chloride.  The cellulose material employed may be in the form of undried rayon yarn produced by washing rayon cake, or an undried tow of continuous filaments of rayon produced by the viscose or cuprammonium processes or rayon staple obtained by cutting an undried tow of continuous filaments.  The products are soluble in a 0.17 per cent aqueous solution of sodium carbonate at 90 DEG  C. and soluble in a boiling 0.5 per cent formic acid or boiling 0.01 per cent hydrochloric acid solution.  In an example a washed undried regenerated cellulose yarn is impregnated for 2-3 minutes with an aqueous solution consisting of 13 c.c. of 15 N sulphuric acid, 12 grams of ammonium sulphate, 0.5 gram of ammonium dihydrogen phosphate and 30 c.c. of 30-35 per cent cyanamide solution.  The impregnated yarn is hydro-extracted, dried at about 60 DEG  C., baked for 2 1/2 minutes at 160 DEG  C. and washed in a solution of 30-40 per cent by volume of alcohol in water.  The products of the invention are said to be fire-resistant and when in the form of yarns may be used as carrier yarns or core yarns in the production of effect threads or fabrics.  Specifications 634,690 and 647,321 are referred to.