PROCESS FOR POLYMERIZING VINYL ARYL COMPOUNDS WITH T-BUTYLPEROXY ISOPROPYL CARBONATE AND BENZOYL PEROXIDE

摘要

A polymerizable liquid containing monovinyl aryl compounds of formula C6H3RR1-CH=CH2, where R and R1 are H, halogen or C1- 4 alkyl groups and from 0-50% of another copolymerizable monoethylenically unsaturated monomer is polymerized by heating to 80-150 DEG C. in the presence of a catalyst mixture consisting of a tert.-butylperoxy isopropyl carbonate and a peroxide of formula (C6R5COO)2, where the R's may be H, halogen or C1- 4 alkyl or alkoxy. The monomer may be styrene, o-vinyltoluene, vinyl-xylene or p-tert.-butyl styrene or a mixture of m- and p-vinyltoluene; styrene and methyl methacrylate, a -methylstyrene, acrylonitrile or vinyl propionate; or isopropyl styrene and p-tert.-butylstyrene. The peroxide may be benzoyl peroxide, p-chlorobenzoyl peroxide or 2,4-dichlorobenzoyl peroxide. The polymerization may be carried out in aqueous suspension using zinc oxide, basic magnesium carbonate, hydroxyapatite, sodium polyvinyltoluene sulphonate and/or ammonium sulphate as dispersing agents. A blowing agent, e.g. n-pentane, may be present during polymerization and the polymer beads may be heated with steam to form a porous product. In an example polystyrene beads formed as above an aqueous suspension were mixed with bis-(bromopropyl) bromopropyl phosphonate of empirical formula dicumylperoxide and n-pentane and the mixture was heated to 95 DEG C. to produce a self-extinguishing expandable polystyrene.