Patent GB-313408-A (GB)
Title: Improvements in the manufacture of cellulose esters
IPC: C08B3/00
Filed: 1928-03-27
Abstract: 313,408. Kodak, Ltd., (Assignees of Clarke, H. T., Malm, C. J., and Stinchfield, R. L.). March 28, 1927, [Convention date]. Divided on 287,880. Cellulose carboxylates, and processes for making filaments and films therefrom.-Cellulose esters of organic acids, other than the esters of the higher homologues of acetic acid, are prepared by treating cellulose, or a cellulose conversion product or derivative, with the organic acid in question in the presence of a substituted organic acid anhydride. The anhydride induces the esterification of the cellulose by the organic acid present, and this effect is the more noticeable in the case of substituted anhydrides not capable of esterifying cellulose. The anhydride of the organic acid may be used in place of the latter. Suitable substituted anhydrides are the halogen and alkyloxy derivatives of the acetic series, particularly such as contain less than 10 carbon atoms in the molecule, especially chloracetic anhydride. The organic acid used for esterification may be an unsubstituted aliphatic monocarboxylic, acid, including the monocarboxylic acids derived from the cycloparaffins, an aromatic monocarboxylic acid, an aralkyl monocarboxylic acid and a substituted aromatic monocarboxylic acid; also an aromatic dicarboxylic acid provided that one of the carboxyl groups is rendered inactive as by esterification, and an unsubstituted aliphatic monocarboxylic acid containing a double bond especially if the latter is in the alpha-#-position with respect to the carboxyl group. The esterification bath should preferably contain a solvent for both the organic acid and the anhydride; halogen acetic acids are particularly suitable. The presence of an esterification catalyst is also advantageous. The process is of particular importance as regards the manufacture of mixed esters containing acyl groups derived from fatty acids containing more than 8 carbon atoms, and also acyl groups derived from fatty acids containing more than one and less than 5 carbon atoms; such esters are acetone soluble, and they give films, filaments, &c. exhibiting good flexibility and for such uses they may be employed in conjunction with plasticizing agents. By the use of non-esterifying anhydrides, cellulose formates containing 7 or more formyl groups for each molecule of cellulose (C24) may be prepared; these esters are also soluble in acetone. Cellulose esters containing halogen aromatic acyl groups either alone or in conjunction with other acyl groups, may also be prepared. The starting material may be undegraded cellulose, hydrocellulose, reverted cellulose and lower nitrates, acetates, formates or ethers. In examples, cellulose acetate is obtained by treating cotton with a mixture of glacial acetic acid, chloracetic anhydride and magnesium perchlorate; similarly. the following cellulose esters may be prepared by the use of the appropiate organic acid together with chioracetio anhydride and magnesium perchlorate-prapianates, n-butyrates, isobutyrates, n - valeriates, isovaleriates, n - caproates, nheptylates, caprylates, pelargonates, caprates, laurates, myristates, palmitates, stearates, crotcnates, cyclohexane carboxylates, benzoates, omethoxybenzoates, o - chlorobenzoates, acetylsalicylates, phenylacetates, hydrocinnamates, cinnamates and mixed esters derived from stearic and acetic acids and from o-methoxybenzoic and acetic acids; cellulose is treated with chloracetic anhydride and formic acid to produce either a diformate soluble in acetone or a lower product insoluble in acetone if the reaction :is allowed to proceed for a shorter time or if a further addition of formic acid and chloracetic anhydride is made, a product higher than a diformate and soluble in acetone; the product obtained according to the latter process may be added to a mixture of stearic acid, chloracetic anhydride, and magnesium perchlorate to give a cellulose formylstearate; cotton is treated with monochloracetic anhydride, o-chlorbenzoic acid, acetic acid, and magnesium perchlorate to produce a mixed acetate-chlorbenzoate, which is soluble in chloroform or acetone according to the proportion of acetic acid employed; cotton tissue paper is treated with ethyl hydrogen phthalate, chloracetic anhydride, and magnesium perchlorate, to produce a phthalic acid ester soluble in acetone, chloroform, and benzol, or a mixed acetatephthalate if acetic acid is added to the reaction mixture, the mixed ester exhibiting similar solubilities. Specification 285,858 is referred to. The Specification as open to inspection under Sect. 91 (3) (a) includes also the production of cellulose esters of the higher homologues of acetic acid with the aid of substituted organic acid anhydrides as impellers. This subject-matter does not appear in the Specification as accepted.