GB398626A - Improved treatment of mixed organic esters of cellulose - Google Patents

Abstract

The solubility characteristics of acetone-soluble mixed organic esters of cellulose are changed by treating the esters with a hydrolyzing agent. Particularly useful in the production of films and filaments are the originally acetone-soluble and subsequently hydrolyzed mixed esters of cellulose, the acyl content of which comprises at least 15 per cent of fatty acid radicle higher than acetyl (calculated on the weight of the mixed ester before hydrolysis). Mixed esters specified are the acetate-propionate, acetate-propionate-butyrate, acetate-butyrate, acetate-stearate, and acetate-laurate, obtained, for example, according to the process of Specification 287,880, [Class 2 (ii), Cellulose]. A dilute mineral acid is preferred as the hydrolyzing agent, particularly when used in the presence of a sufficient quantity of organic acid to prevent precipitation of the cellulose ester. The hydrolysis may be carried out at about 100 DEG F. for from 1 to 360 hours. The "precipitation value" of the hydrolyzed ester, which is defined as the percentage of ester which from an acetone solution thereof, will be precipitated in a mixture of 40 per cent of water and 60 per cent of acetone by volume, is preferably above 85 per cent. The following examples are given:--(1) A reaction mixture comprising fully esterified cellulose acetate-propionate, propionic acid, acetic acid, and sulphuric acid is diluted with aqueous acetic acid and heated to 100 DEG F. (2) A reaction mass comprising fully esterified cellulose acetate-butyrate, butyric acid, acetic acid, sodium acetate, and sulphuric acid is diluted with aqueous acetic acid and kept at 100 DEG F. Figures are given showing the effect of hydrolysis on solubility in various solvents, and the flexibility of films produced from the esters at various degrees of hydrolysis. The products may be employed in the production of filaments, films, plastics, lacquers, &c. Specifications 219,926, 313,408, [both in Class 2 (ii), Cellulose &c.], and 388,303 also are referred to. The Specification as open to inspection under Sect. 91 includes processes for hydrolyzing mixed esters of cellulose other than acetone-soluble esters. This subject-matter does not appear in the Specification as accepted.