Patent GB-287880-A (GB)
Title: Improvements in the manufacture of cellulose esters
IPC: C08B3/08
Filed: 1928-03-27
Abstract: 287,880. Kodak, Ltd., (Assignees of Clarke, H. T., Malm, C. J., and Stinchfield, R. L.). March 28, 1927, [Convention date]. Grant of Patent opposed. Cellulose carboxylates, and processes for making filaments and films therefrom.-Mixed esters of cellulose with organic acids are prepared by treating cellulose, or a cellulose conversion product or derivative, with an organic acid in the presence of the anhydride of an acid containing a smaller number of carbon atoms than the acid used for esterification. 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 aminocarboxylic acid. 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. Esters containing the following groups may be prepared according to the present process,-propionic, n-butyric, isobutyric, n-valeric, isovaleric, n-heptylic, lauric, myristic, palmitic, stearic, cyclohexane carboxylic, crotonic, cinnamic, hydrocinnamic, and benzoic. 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 soluble in acetone, 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. The starting material may be undegraded cellulose, hydrocellulose, reverted cellulose, and lower nitrates, acetates, formates or ethers. In examples, cotton is treated with a mixture of propionic acid, acetic anhydride, glacial acetic acid and zinc chloride, and the solution obtained is poured into water to separate the ester which contains both a.cetyl and propional groups; cotton tissue paper is treated with a mixture of commercial stearic acid, acetic anhydride, chloracetic acid and magnesium perchlorate, and the solution poured into methyl alcohol to isolate a product which is an aceto-palmito-stearate of cellulose; cotton or tissue paper is mixed with chloracetic acid, orthomethoxybenzoic acid and magnesium perchlorate, and the product, which is a cellulose aceto-methoxybenzoate, isolated by precipitation with methyl alcohol; cotton is mixed with propionic acid containing perchloric acid, then pressed and treated with carbon tetrachloride and acetic anhydride, a product which is still fibrous and which is soluble in acetone, being eventually obtained; cotton tissue paper is treated with acetic anhydride and either tannic, myristic, palmitic, or stearic acid, or mixtures of them, and magnesium perchlorate, and the ester isolated by precipitation with methyl alcohol; a hydrolyzed cellulose acetate containing 9 or 10 acetyl groups for each C24 atoms in the cellulose, is treated with acetic anhydride, stearic acid, chloracetic acid, and magnesium perchlorate for the purpose of introducing stearyl groups into the molecule. Specifications 27102/09 and 16000/11 are referred to. The Specification as open to inspection under Sect. 91 (3) (a) refers to the preparations of simple or mixed cellulose esters with the aid of a substituted organic acid anhydride, particularly halogen or alkoxy substituted derivatives especially chloracetic anhydride; it includes the following classes of organic acids that may be used in the esterification,-aromatic dicarboxylic acid in which one of the carboxyl groups is rendered inactive as by esterification, and unsubstituted aliphatic monocarboxylic acids containing a double bond especially such as have the double bond in the a or # position with respect to the carboxyl group, and also substituted aromatic carboxylic acids such as chlor- and methoxy-benzoic acids, and acetylsalicylic acid, and it also mentions the use of phenylacetic acid; and it contains the following examples :-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 is added to a mixture of stearic acid, chloracetic anhydride and magnesium perchlorate to produce a cellulose formyl-stearate; cotton is treated with monochloracetic anhydride, o-chlorbenzoic acid, acetic acid, and magnesium perchlorate, to produce a mixed acetate-chlorbenzoate of cellulose, 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 benzene, or a mixed acetate-phthalate if acetic acid is added to the reaction mixture, the mixed ester exhibiting similar solubilities. This subject-matter does not appear in the Specification as accepted.