Patent GB-177810-A (GB)
Title: Manufacture of cellulose derivatives
IPC: C08B11/02
Filed: 1922-04-01
Abstract: Stable cellulose derivatives that contain alkyl or aralkyl groups and are insoluble in water and the usual organic solvents, but are soluble in alkali solutions, are prepared by heating cellulose or a conversion product of cellulose not soluble in caustic alkali in the presence of alkylating- or aralkylating-agents with such a quantity of caustic alkali solution of less than 50 per cent strength as is not sufficient of itself under the conditions obtaining, to convert cellulose into an alkali-soluble conversion-product. Suitable parent materials are cellulose, or an alkali-insoluble cellulose hydrate, hydrocellulose hydrate or oxycellulose, or an aliphatic acid ester of cellulose. The parent material, is impregnated with the alkali solution, and the mixture, is either immediately or after standing, warmed or heated with an alkyl or aralkyl ester of an inorganic acid. Alternatively, the cellulose, &c. may be warmed with the alkali solution and then heated with the alkylating, &c. agent. Generally the weight of alkali will not exceed that of the air-dried cellulose, &c., although much smaller quantities will suffice, and for each molecular equivalent of cellulose not more than three molecular equivalents will be used, although normally two molecular equivalents will be adequate if cellulose is employed, one and a half equivalents if a cellulose conversion-product is selected. However, the new cellulose derivatives are formed in the presence of much larger amounts of alkali and alkylating agent, provided that the concentration of the alkali is not considerably greater than 18-20 per cent and at any rate less than 15 per cent.  The derivatives if insoluble in the reaction mixtures, are washed with water, acid, alcohol, alcohol ether, and then dried, or alternatively, while still moist, dissolved in alkali solution; if the reaction mixture is a viscous solution it may be employed as such, or the cellulose derivatives may be isolated by precipitation with water or acid, and subsequent treatment as in the first case.  The new cellulose derivatives are precipitated from their solutions in alkali, by acids, acid salts, acids and salts, alcohol, &c., that is, the precipitating media usually employed with viscose.  Technically, the derivatives are used in alkali solution and are eventually precipitated by acids, etc.; working in this manner they may be used for the manufacture of films, artificial threads, plastic masses, paints, finishes, filling-materials, sizing- or binding-agents, adhesives, thickening-materials, fixing-media for pigments in textile printing, and as coatings or layers; and in working up the materials into these products there may be added before the final precipitation, softening, &c. agents such as oils, fats, glycerine, sugar, soaps; and turkey red oil or its substitutes. In examples, 100 parts of sulphite cellulose are impregnated with 900 parts of 8-10 per cent caustic soda solution, allowed to stand, pressed to 250 parts, and the comminuted residue mixed with 12.5-20 parts of ethyl chloride heated in an autoclave to 80-85 DEG  C, the reaction mass being either dissolved in 5-10 per cent caustic soda solution or precipitated with water or acid; alternatively, a 12-13 per cent caustic soda solution may be used for impregnating the cellulose, and the product pressed to 200 parts; alternatively, the cellulose may be impregnated with a 18 per cent caustic soda solution, pressed to 250-350 parts, and treated with 12.5-14 parts of ethyl chloride at 70-110 DEG  C.  The Specification as open to inspection under Sect. 91 (3) (a) includes also a process in which the starting material is an alkali-soluble cellulose derivative such as a xanthate, and also a number of additional examples which are as follows:-100 parts of sulphite cellulose are impregnated with 1000 parts of 18 per cent caustic soda solution, and after standing for 2 or 3 days treated without pressing, with 200-235 parts of ethyl chloride at 70-110 DEG C.; 100 parts of sulphite cellulose are impregnated with 900-1000 parts of 18 per cent caustic soda solution, allowed to stand, pressed to 250-360 parts, comminuted, 40-60 parts of diethyl sulphate added, and the mixture heated to 40-60 DEG  C., the product being worked up as in the first example; 100 parts of sulphite cellulose are mixed with 50 parts of powdered caustic soda while cooling, and the comminuted mixture treated either immediately or after standing, with 80 parts of ethyl chloride at a temperature of 100-110 DEG  C; to 1000 parts of a viscose solution prepared for example according to Specification 14339/14, and containing 160-170 parts of celulose and 160-170 parts of caustic soda, are added, after slight warming, 50-100 parts of diethyl sulphate, and the heating continued, while stirring, until a temperature of 40-45 DEG  C. is reached-the resulting viscous solution may be used directly, or the product may be first isolated by precipitation with water with or without acid. This subject-matter does not appear in the Specification as accepted.