GB282793A - Process of producing cellulose esters - Google Patents

Abstract

282,793. Ruth-Aldo Co., Inc., (Assignees of Barthelemy, H. L.). Dec. 28, 1926, [Convention date]. Cellulose acetates and other carboxylates.- For the esterification of cellulose and of nitrocelluloses of low nitrogen content, there is employed an acetylation mixture containing acid anhydride, particularly acetic anhydride, and a catalyst such as sulphuric acid, together with a reagent capable of effecting a mild oxidation of the cellulose &c. The process is particularly applicable to the acetylation of cotton, having the effect of giving uniform products from cottons which would otherwise produce acetates of varying properties particularly as regards their viscosity characteristies. The reagent must be added in such an amount that the amount of active oxygen employed is not in excess of 0.3 per cent of the weight of the cotton. Suitable reagents are manganic sulphates, manganic acetate, chromic acid, mono-persulphuric acid, manganic and permanganic acid, and peracetic acid. In examples, cotton is first treated with acetic acid, and then with acetylation mixture containing a limited proportion of acetic anhydride, sodium bichromate or permanganate, sulphuric acid and acetic acid, if necessary with cooling; later the remainder of the anhydride is added, and the reaction allowed to proceed until solution is complete. The cellulose carboxylate is then partially saponified by known methods and after flocculation is thoroughly washed to remove the salts.