Patent GB-536807-A (GB)
Title: Method of producing fusible acrylate polymers, and infusible polymers therefrom
IPC: C08F20/12
Filed: 1939-08-22
Abstract: 536,807. Vinyl polymerization products. PITTSBURGH PLATE GLASS CO. Aug. 22, 1939, No. 24210. Convention date, Aug. 23, 1938. [Class 2 (iii)] Fusible polymers of olefinic monohydric alcohol esters of acrylic and α-substituted acrylic acids are produced by polymerizing the monomeric esters in solution, and stopping polymerization before the gel state has been attained, i.e. at the point of incipient gelation. The fusible polymers may be rendered infusible by further polymerization, e.g. by heating somewhat above their softening points. The polymerization may be stopped and the fusible polymer separated by precipitation with a non-solvent therefor, e.g. methyl or ethyl alcohol, petroleum ether, water or ethylene glycol. Alternatively, the polymerization may be stopped by cooling, or by the addition of a polymerization inhibitor, e.g. pyrogallol, hydroquinone, aniline, phenylene diamine, sulphur, thiophenol or dipentene ; the solution may then be used as such, or the fusible polymer may be separated by slow evaporation of the solvent or by the addition of a non-solvent. Esters specified are allyl, methallyl, crotyl, cyclohexenyl and oleyl esters of acrylic, methacrylic and chloracrylic acids, and specified solvents are acetone, dioxane, chloroform, toluene, benzene, carbon tetrachloride, glycol monomethyl or monoethyl ether acetate, glycol monophenyl ether, dichloroethyl ether, xylene, tetrahydronaphthalene and dibutyl phthalate. Fusible copolymers may be produced by effecting the polymerization in the presence of a saturated acrylic or α-substituted acrylic ester, e.g. methyl, ethyl and propyl methacrylate or choracrylate, styrene, vinyl chloride or vinyl acetate, which substances may act as the solvent for the unsaturated ester. Fillers, such as wood-flour, mica or cotton flock, plasticizers such as dibutyl phthalate, dicyclohexyl phthalate, triacetin or tricresyl phosphate, natural or synthetic resins, pigments, e.g. titanium dioxide, carbon black, chromic acid or lead chromate, and organic dyestuffs, e.g. methylene blue or methyl orange may be incorporated in the fusible polymers. Other polymers, including polymers of methyl methacrylate, methylchloracrylate, vinyl acetate, vinyl chloride and styrene may be incorporated in the fusible polymers, and the mixture polymerized to the infusible state. The fusible polymers may be moulded, used as safety glass or in the manufacture of laminated products or incorporated in lacquers, or impregnating or coating compositions, the products being subsequently heated to render the polymer infusible. In examples : (1) and (2) a solution of allyl methacrylate or allyl chloracrylate, respectively, and benzoyl peroxide in acetone is heated under reflux until incipient gelation occurs, the fusible polymer being then precipitated from the solution by the addition of methanol, (3), (4) and (5) fusible polymers of allyl methacrylate, allyl chloracrylate or allyl acrylate are fused and heated under pressure to give insoluble products, and (6) a solution of the fusible polymer of methallyl methacrylate in acetone is applied as a coating to a cast sheet of polymethyl methacrylate, the solvent evaporated, and the product heated to render the coating infusible. Specification 465,789 is referred to.