Patent GB-357549-A (GB)
Title: A manufacture of artificial threads and other materials from cellulose compounds
IPC: C08B13/02
Filed: 1930-03-15
Abstract: Artificial silk, films, and other products are obtained by reacting on a cellulose derivative containing one or more CSS- groups with an alkylene halide, and after bringing the product into the appropriate shape or form, acting thereon with an agent having a coagulating effect.  The coagulating agent may be one which also has a plasticizing effect on the freshly coagulated material. Alternatively, the product may first be treated with a coagulating agent and then with a plasticizing agent.  Thorough and prolonged stirring of the alkylene halide and cellulose xanthate solution results in products of increased extensibility. Any one of the coagulating liquids known in the viscose art, or the art of making alkali-soluble cellulose derivatives or cellulose conversion products may be employed.  The baths may contain in addition to acids, and salts, also other inorganic or organic substances.  As plasticizing agent, sulphuric acid of not less than about 30 per cent or an equivalent quantity of another mineral acid may be used.  Any other plasticizing agent may be used.  The plasticizing agent may be mixed with strong mineral acid such as hydrochloric acid, nitric acid, or phosphoric acid, or with a salt such as sodium or ammonium sulphate or bisulphate, sodium sulphite or bisulphite, sodium nitrite, zinc or magnesium sulphate; or boric acid.  Organic substances such as glycerine, glucose, alcohol, a salt of aniline or pyridine, an aldehyde, acetic, formic, lactic, or oxalic acid may also be added. In an example ethylene chloride is added to viscose with stirring which is continued for several hours each day during the ripening process which lasts about four days.  The solution is filtered and spun into a plasticizing bath containing from 40-70 per cent or more of sulphuric acid.  In another example the solution is first spun into ammonium sulphate solution, or dilute sulphuric acid and sodium bisulphate, or dilute sulphuric acid and sodium, ammonium, and zinc sulphates, and glucose.  The threads are then passed through strong sulphuric acid.  In the preparation of the viscose, the cellulose may be directly mixed with the amount of caustic soda required in the viscose.  Instead of ethylene chloride, propylene chloride, or trimethylene chloride may be used.  Copper acetate or zinc acetate may be added to the viscose before the addition of the alkylene halide.  The viscose may be subjected to the action of a halogen derivative of a di- or polyhydric alcohol such as a -dichlorhydrin, a -monochlorhydrin, or ethylene chlorhydrin in addition to that of the alkylene halide.  In an example, cotton material is impregnated or coated on a padding, backfilling, or spreading machine with a solution of viscose and alkylene halide and to the solution talc, china clay, mica or lampblack may be added.  The material with or without being dried, is passed if desired under tension through a coagulating or plasticizing bath.  It is then washed and dried.  In the preparation of the viscose, wood pulp or cotton linters which has been pretreated with mineral or organic acids, mercerized cellulose, or regenerated cellulose may be used.  Instead of alkylene chlorides, the corresponding bromine or iodine compounds may be used.  Instead of strong sulphuric acid, an equivalent concentration of hydrochloric, nitric, phosphoric, or arsenic acid may be used, or a plasticizing agent such as zinc chloride in hydrochloric acid may be used.  The Provisional Specification refers also to the addition of methylene chloride, ethylidene chloride, propylidene and isopropylidene chloride, and tetra- and pentachlorethane to viscose. Specifications 335,906, [Class 2 (ii), Cellulose &c.], 341,843, 357,121, 357,192, and 357,526 are referred to.