GB275641A - Process for the production of cellulose esters - Google Patents

Abstract

275,641. El÷d, E. Aug. 4, 1927. [A Specification was laid open to inspection under Sect. 91 of the Acts, Aug, 10, 1927]. Cellulose formates.-Cellulose is esterified with highly concentrated formic acid such as 98-100 per cent, in presence of considerable quantities of swelling-agents such as zinc chloride or calcium bromide and of catalysts which assist the esterification but not the degradation of the cellulose, the reaction being carried out at temperatures between 5 and 30‹ C., and interrupted when the desired degree of esterification has been effected. The catalysts mentioned are hydrochloric acid and phosphoric anhydride. In the examples slightly nitrated cellulose is mixed at ordinary temperature with anhydrous zinc chloride and absolute formic acid saturated with hydrochloric acid, the reaction being interrupted after about an hour by pouring into water, after which the precipitate is dried and dissolved in diformin; linters are treated in a similar manner, the reaction being interrupted after 20-30 minutes and the product dissolved in formamide. The cellulose formate may be dissolved in suitable solvents such as thiocvanates of the alkalies and alkaline earths, nitromethane, fonnamides, glycerol formates, chlorhydrins or mixtures of such solvents with or without plastifying agents. The Specification as open to inspection under Sect. 91 (3) (a) of the Act states that the esterification may be carried out at low temperatures such as below 0‹ C. to retard the degradation of this cellulose. This subject-matter does not appear in the Specification as accepted.