| abstract |
Expandable thermoplastic resin particles having excellent heat resistance, solvent resistance, foamability and moldability comprising a copolymer of 10 to 80% by weight of a-methyl styrene, 5 to 50% by weight of acrylonitrile and 0 to 70% by weight of at least one member selected from the group consisting of styrene, methyl methacrylate, vinyl toluene and t-butylstyrene, and an expanding agent impregnated in the copolymer, prepared easily in high conversions by an aqueous suspension polymerization using particular difunctional organic peroxides, preferably those capable of producing t-butoxy radicals, followed by impregnation of the produced polymer particles with the expanding agent. |