Patent GB-410125-A (GB)
Title: Manufacture of organic esters of cellulose and its derivatives
IPC: C08B3/12
Filed: 1932-08-10
Abstract: Cellulose dicarboxylates are made by treating cellulose, preferably regenerated, pretreated, modified, or partially etherified or esterified, in an undissolved state with a dicarboxylic acid anhydride other than phthalic anhydride in presence of an anhydrous tertiary organic base, and preferably continuing the treatment until a dope is formed.  Suitable dicarboxylic acid anhydrides include alkyl and aryl dicarboxylic anhydrides, and anhydrides of acids in which the carboxyl groups are joined by heterogeneous atoms as well as carbon atoms. Examples are succinic acid and its homologues such as glutaric acid, diglycollic, dilactic and dihydracylic acids, and the dicarboxylic acids formed by the ethers of the higher hydroxymonobasic acids such as hydroxybutyric acid or hydroxy valeric acid.  Acid anhydrides containing sulphur atoms instead of or in addition to oxygen atoms, for example, thiodiglycollic or thiodilactic acid anhydride may also be used.  Aryl carboxylic acids of which the anhydrides may be used include the substituted phthalic acids containing nitro, alkyl, or methyl, or like groups other than hydroxyl groups, or naphthalic acid or anthraquinone 1.2-dicarboxylic acid.  Suitable tertiary organic bases include pyridine, dimethyl - N - hexylamine dimethylaniline or other dialkyl anilines, and hexahydrodialkyl anilines.  Examples of compounds which can be prepared by the invention are cellulose acetate, diglycollate, cellulose acetate dilactate, cellulose acetate dihydracrylate, cellulose diglycollate, cellulose dilactate, cellulose dihydracrylate, cellulose acetate propionate diglycollate, cellulose ethyl ether diglycollate, cellulose acetate diglycollate, thiodilactate, cellulose acetate diglycollate dilactate, cellulose thiodiglycollate, cellulose acetate thiodiglycollate, and cellulose acetate thiodilactate. The esters of the heterogeneously linked dicarboxylic acids are generally soluble in various pyridine mixtures such as pyridineacetone, pyridine-benzene, pyridine tetrachlorethane, and pyridine-ethylene chloride, any of which last-named three mixtures may be used instead of pyridine alone as solvents or reactive media.  Lists of organic solvents suitable for dissolving a cellulose acetate diglycollate and for dissolving succinic esters made according to the invention are given.  From solutions of the esters in suitable solvents transparent sheets or skins may be formed, plasticisers such as ethyl, butyl, or other alkyl phthalate, triphenyl or tricresyl phosphate, a b -alkoxyalkyl phthalate or tributyl phosphate being added.  The heterogeneously linked esters are suitable for use as an intermediate layer between the base and the sensitized emulsion of photographic films, for laminating sheets of glass, metals, wood, leather, fabric &c., for sheeting, artificial silk, moulded products, or artificial leather.  As plasticisers for use in the preparation of moulded products from the succinic esters, especially the acetate-succinates, p-methoxyethyl phthalate is particularly suitable.  Examples are given; starting materials employed therein include cellulose, regenerated cellulose, partially acetylated cellulose acetate propionate and cellulose acetates, and partially etherified cellulose ethyl ether.  The product is generally obtained combined with the organic base, from which it may be freed by treatment with a mineral acid.  Solvents for the products of the examples are specified, and in several cases it is stated that water-soluble salts are formed by the addition of alkalis thereto, Specifications 398,626 and 410,118 are referred to.  The Provisional Specification mentions quinoline as a suitable organic base, and specifies as solvents which may be added to the reaction mixture benzene, tetrachlorethane, and ethylene chloride.  It also states that the cellulose acetate dicarboxylates formed may be neutralized with aqueous solutions of inorganic water-soluble hydroxides to form water-soluble salts which may be coated out from thin solutions to form sheets and skins.  The Provisional Specification also refers to Specification 410,126.ALSO:Cellulose dicarboxylates, especially those in which the carboxyl groups are linked by heterogeneous atoms, are used in the manufacture of moulded products &c.  Dicarboxylic acids specified include succinic and glutaric acids and the like, diglycollic, dilactic, dihydracrylic acids, acids derived from the ethers of hydroxybutyric acid, hydroxyvaleric acid, and the like, and aryl carboxylic acids such as phthalic acids substituted with nitro, alkyl, methyl or like groups, naphthalic acid, and anthraquinone 1.2-dicarboxylic acid.  Esters specifically mentioned are cellulose acetate diglycollate, cellulose acetate dilactate, cellulose acetate dihydracrylate, cellulose diglycollate, cellulose dilactate, cellulose dihydracrylate, cellulose acetate propionate diglycollate, cellulose ethyl ether diglycollate, cellulose acetate diglycollate thiodilactate, cellulose acetate diglycollate dilactate, cellulose thiodiglycollate, cellulose acetate thiodiglycollate, and cellulose, acetate thiodilactate.  These esters are generally soluble in pyridine and in mixtures of pyridine with organic solvents, and certain organic solvents suitable for particular esters are specified.  From solutions of the esters in suitable solvents sheets or skins may be formed, plasticizers such as ethyl, butyl, or other alkyl phthalate, tricresyl or triphenyl phosphate, a b -alkoxyalkyl phthalate, or tributyl phosphate being added.  As plasticisers for use in the preparation of moulded products from the succinic esters, especially the acetate succinates, b -methoxyethyl phthalate is particularly suitable. Specifications 398,626, [Group IV]; 410,118; and 410,126, [Group IV], are referred to.