GB1451132A - Foam materials and the preparation thereof - Google Patents

Abstract

1451132 Foams derived from expandable styrene/acrylonitrile copolymers DOW CHEMICAL CO 21 Jan 1974 2749/74 Headings C3C and C3R A foam comprises a matrix of an open cell flexible foam, the matrix having dispersed in all or portion thereof a plurality of closed cell expanded particles of a copolymer of 92-60% by wt. styrene and 8-40% by wt. acrylonitrile which has been cross-linked to the extent that when unexpanded particles of the polymer containing no foaming agent are placed in dimethylformamide at 25‹ C. they form a coherent gel and show a swelling ratio (i.e. the ratio of the wt. of the swollen gel to the wt. of the unswollen particle) of 10-50. The crosslinked copolymers may be formed by polymerizing styrene and acrylonitrile in the presence of divinylbenzene or by treating a styrene/ acrylonitrile copolymer with the diglycidyl ether of bisphenol A and the expanded particles are made from expandable particles of the crosslinked copolymer containing a volatile fluid foaming agent, e.g. dichlorodifluoromethane, trichlorofluoromethane and/or trifluorotrichloroethane. The foam is made by mixing a selfreacting exothermic open cell foam forming composition, e.g. a polyurethane forming composition comprising a polypropylene oxide triol, water, a silicone surfactant and toluene diisocyanate with optionally trichlorofluoromethane, with the above expandable particles which form a closed cell foam, and casting or moulding the mixture into a desired shape while the expandable particles foam. The foams may be used as a filler for cushions, furniture and toys.