Patent GB-647321-A (GB)
Title: Improvements in and relating to the production of a water-soluble cellulose compound
IPC: D06M15/05
Filed: 1948-07-27
Abstract: Cellulose material is impregnated with an aqueous solution containing sulphuric acid and cyanamide and the impregnated material is treated to complete the reaction between the cellulose, sulphuric acid and cyanamide, the impregnated material containing sufficient sulphuric acid to produce a final water-soluble product which contains not less than 25 per cent by weight of combined sulphuric acid.  The term "water-soluble product" is defined as including products which are soluble in water at temperatures of 50 DEG  C. and above as well as products which are soluble at ordinary atmospheric temperatures of about 20 DEG  C.  The impregnating solution may contain an alkali metal sulphate or ammonium sulphate.  The process may be carried out on regenerated cellulose material, e.g. rayon filaments made by the viscose or cuprammonium process which may be in the undried or dried state.  Alternatively the cellulose material may be a natural fibre such as cotton.  The treatment necessary to complete the reaction between the cellulose, sulphuric acid and cyanamide may consist of a drying step alone, e.g. for 10-30 minutes at 85-100 DEG  C., or a drying step, e.g. heating for 5-30 minutes at 50-80 DEG  C., followed by a baking step, e.g. heating at 120-160 DEG  C. for 5-30 minutes. In an example a skein of washed undried rayon yarn is impregnated with an aqueous solution containing 13.3 per cent of cyanamide, 15.5 per cent of sulphuric acid and 16.9 per cent of ammonium sulphate. The skein is hydro-extracted to a 28 per cent cellulose content, dried at 54 DEG  C. for 7 minutes and baked at 140 DEG  C. for 10 minutes.  The skein is then washed in 50 per cent alcohol and dried. In another example a skein of dry cotton is subjected to a swelling treatment by immersion in 20 per cent caustic soda solution at room temperature for 10 minutes, washed free from caustic soda and hydroextracted before being treated in a manner similar to that described in the previous example.  The cellulose material treated in accordance with the present invention is said to have fire-resistant properties and it is stated that when in the form of yarn it may be used as carrier or core yarns (see Group IV (c)).  The water-soluble cellulose compounds obtained are also said to be suitable for the production of sizes.  Specification 634,690 is referred to.  The first Provisional Specification describes also the treatment of cellulose material as above, but in such a manner that the final product contains not less than 10 per cent by weight of combined sulphuric acid.ALSO:Cellulose textile material, e.g. viscose rayon yarn or cotton, is impregnated with an aqueous solution containing sulphuric acid and cyanamide and the impregnated material is treated to complete the reaction between the cellulose, sulphuric acid and cyanamide, the impregnated material containing sufficient sulphuric acid to produce a final water-soluble product which contains not less than 25 per cent by weight of combined sulphuric acid (see Group IV (a)).  Yarns treated in the above manner may be used as carrier yarns or core yarns in the production of effect threads or fabrics, for example the water-soluble yarn may be used as a scaffolding thread to support a yarn which is not capable of withstanding the normal wearing process and the water-soluble yarn may be subsequently removed by washing.  Specification 634,690 is referred to.  The first Provisional Specification describes also the treatment of cellulose material as above but in such a manner that the final product contains not less than 10 per cent by weight of combined sulphuric acid.