GB967921A - Improvements in or relating to the copolymerisation of unsaturated polyester resins and vinyl monomers - Google Patents

Abstract

An improvement in the copolymerization of unsaturated polyesters with monomers capable of vinyl polymerization under the action of organic peroxides and in the presence of copper or copper-containing alloys, comprises adding to the compounds to be copolymerized from 0.01 to 29% by weight of an organic acid, the copper salt of which is substantially insoluble in the compounds to be copolymerized. The preferred acids are those having a dissociation constant in the range 10-3 to 10-1 e.g. oxalic, malonic and a ,b -dibromosuccinic; and partially esterified polycarboxylic acids e.g. the monooctyl ester of tricarballylic acid and the monododecyl ester of citric ester. In the examples: (1) An unsaturated polyester formed from adipic acid, fumaric acid and propylene-1, 2 glycol is dissolved in styrene, after which benzoyl peroxide and anhydrous oxalic acid are added, and the mixture cured in the presence of copper strips and finely powdered copper-bronze at 100 DEG C.; (3) Bare copper conductors are wrapped with a layer of absorbent paper and then with a layer of synthetic resin foil based on terephthalic acid ester, and are then impregnated with the unsaturated polyester, styrene, benzoyl peroxide, oxalic acid mixture of Example 1 and hardened at 80 DEG C. In other examples the unsaturated, polyester resin was prepared from adipic acid, fumaric acid and 4,41-bishydroxyethoxy-2, 2-diphenyl propane and the acid added was oxalic, malonic or a , b -dibromosuccinic.