Patent GB-737516-A (GB)
Title: Improvements in or relating to cellulose acetate sorbate and compositions thereof
IPC: D01F2/28
Filed: 1953-06-22
Abstract: Cellulose acetate sorbate and articles made of it are rendered more resistant to the solvent action of organic liquids by heating them at a temperature above 50 DEG  C., but below the decomposition point of the cellulose ester, with a polyfunctional dienophile, i.e. a compound having two or more centres of unsaturation, each capable of undergoing the Diels-Alder reaction with a diene, e.g. butadiene. The polyfunctional dienophile may be a diallyl ester of a dicarboxylic acid such as the phthalate, terephthalate, malonate, oxalate, succinate, glutarate, maleate, fumarate, citrate, adipate or sebacate; a monoallyl ester of an unsaturated acid such as the crotonate, acrylate, cinnamate or methacrylate; diallyl ether; diallyl ketone; triallyl citrate; a glycol, glycerol or pentaerythritol ester of a monocarboxylic unsaturated acid such as the crotonate, acrylate or methacrylate; diallyl cyanamide; methylene bis-acrylamide; a polyallyl cyanurate; diallylidene pentaerythritol diacetal; divinylbenzene; diallyl melamine; or a b -vinyl acrylic ester or amide.  In examples, solutions of 85-95 parts of cellulose acetate sorbate (acetyl D.S. 2.39, sorboyl D.S. 0.06) admixed with 5-15 parts of one of the specified polyfunctional dienophiles in 9 : 1 (by volume) of a solvent are cast to form films.  After evaporation of the solvent, the films are heated at 155-160 DEG  C. to effect cross-linking and polymerization.  If desired, a polymerization catalyst such as a peroxide or actinic light may be present to promote the reaction.  Benzoyl peroxide, tert.-butyl peroxide and cumene hydroperoxide are specified catalysts.  If desired the dienophile, instead of being homogeneously distributed in the cellulose acetate sorbate composition, may also be used as a surface-treating agent.  Thus a yarn of cellulose acetate sorbate may be immersed for 0.2-10 minutes at 25-95 DEG  C. in a solution of the dienophile, then dried and heated to reaction temperature, whereby the solubility of the yarn in acetone is reduced.  When the dienophile contains nitrogen in the molecule, e.g. when it is methylene bis-acrylamide, the product has improved dyeing properties, e.g. it may be dyed readily with a wool dye such as Pontacyl Wool Blue BL.  Compositions containing the cellulose acetate sorbate and the polyfunctional dienophile may be formed into filaments, films, brush bristles, combs and other articles and may be insolubilized during or after being put into useful form.  Textiles formed from the filaments have improved crease-resistance, dimension stability and ability to withstand higher toning temperatures than filaments of untreated cellulose acetate sorbate.  The treated articles are resistant to hydrocarbon solvents, dry cleaning liquids and grease. The cellulose acetate sorbate may be obtained by esterifying cellulose with an anhydride mixture of acetic and sorbic acids. Sulphuric acid may be used as catalyst and methylene chloride as solvent. The triester obtained may be subjected to partial hydrolysis using an organic sulphonic acid such as benzene- or toluene-sulphonic acid as catalyst and aqueous acetic acid as the hydrolysing medium.