Patent ID: 6274641
Filing Date: 2001-08-14
Classification: C08J

Abstract:
A process for preparing a closed cell foam comprising injection into a molten mass of C.sub.8-12 vinyl aromatic polymer comprising:i) from 60 to 100 weight % of one or more C.sub.8-12 vinyl aromatic monomers; andii) from 0 to 40 weight % of one or more monomers selected from the group consisting of C.sub.1-4 alkyl esters of acrylic or methacrylc acid and acrylonitrile and methacrylonitrile;which polymers are grafted onto from 0 to 12 weight % of one or more rubbery polymers selected from the group consisting of:iii) co- and homopolymers of C.sub.4-5 conjugated diolefins; andiv) copolymers comprising from 60 to 85 weight % of one or more C.sub.4-5 conjugated diolefins and from 15 to 40 weight % of a monomer selected from the group consisting of acrylonitrile and methacrylonitrile, said polymer comprising 10 to 45 weight % of a star branched polymer and having a VICAT softening temperature not less than 100.degree. C.; at a temperature from 140 to 235.degree. C. and a pressure from 1500 to 3500 psi from 2 to 15 weight % of one or more blowing agents selected from the group consisting of C.sub.4-6 alkanes, CFCs, HCFCs, HFCs, CO.sub.2, N.sub.2 and mixtures thereof and maintaining saidC.sub.8-12 vinyl aromatic polymer in a molten state and thoroughly mixing said blowing agent with said polymer and extruding said mixture of blowing agent and polymer.