GB651355A - Manufacture of synthetic resins - Google Patents

Abstract

Copolymers are made by polymerizing a mixture comprising an alkyl acrylate containing up to three carbon atoms in the alkyl radical, an alkyl acrylate containing at least four carbon atoms in the alkyl radical and a compound containing two unconjugated double bonds, the proportion of the compound being not greater than 10 per cent of the mixture. The polymerization may be effected in bulk, solution, suspension or emulsion and in the presence of catalysts. Specified compounds are allyl acrylate, allyl methacrylate, diallyl oxalate, diallyl sebacate, diallyl adipate, diallyl tartrate, diallyl itaconate, diallyl sebacate, diallyl phthalate, diallyl formal, diallyl acral, diallyl butal, vinyl crotonate, diallyl crotonal, diallyl phenyl phosphonate, divinyl benzene and crotyl crotonate. Specified alkyl acrylates are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec.-butyl and amyl acrylates. Specified catalysts are hydrogen peroxide, ammonium and potassium persulphates. When the polymerization is effected in aqueous emulsion, emulsifying agents such as sodium oleate, stabilizers such as gelatine, glue or polyvinyl alcohol, buffering agents, e.g. sodium carbonate and surface-tension regulators such as salt of an aliphatic long-chain carboxy acid may be used. The copolymer may be isolated by coagulation with acids or polyvalent metal salts. The copolymers may be modified by heating them with cross-linking agents such as calcium hydroxide, oxides of zinc, magnesium or lead, alone or admixed with paradinitrobenzene, quinone dioxime, para-phenylene diamine, mercaptobenzthiazole, or a mixture of thiazyl sulphides, e.g. bis-4,5-dimethylthiazyl disulphide and bis-4-ethyl thiazyl disulphide. They may also be mixed with unvulcanized rubber and the rubber vulcanized with sulphur. The copolymers and modified copolymers may be milled into sheets or moulded.