GB1308546A - Curable compositions rigid and elastomeric foams and their production - Google Patents

Abstract

1308546 Foams based on polydiene prepolymers TRW Inc 17 March 1970 [17 March 1969] 12796/70 Heading C3C A plastics foam is made by homogeneously dispersing a foaming agent in a liquid mixture containing a polyfunctional polydiene prepolymer having at least 50% of its olefinic unsaturation in the form of pendant vinyl groups on alternate carbon atoms of a backbone carbon chain, a polyfunctional organic chain-extender capable of reacting with the functional groups on the polydiene prepolymer, and a peroxide free radical initiator capable of curing the mixture to a thermoset resin, and activating the foaming agent and reacting the mixture by chain extension to produce a curable foamed elastomeric resin having the unreacted peroxide initiator molecularly dispersed therethrough. The foamed elastomer may be cured to produce a foam having a thermoset resin matrix having a Barcol hardness of at least 25. Alternatively, a cured foam may be made by heating the dispersion of the foaming agent in the liquid mixture to yield in one step a thermoset foam. The polydiene may be a 1,2-polybutadiene or 3,4-polyisoprene which has (i) hydroxy, (ii) carboxyl or (iii) amino groups at opposite ends of the molecule and the respective chain extender may be an aliphatic or aromatic (i) diisocyanate, diacid halide, dicarboxylic acid or diester; (ii) diepoxide, diamine, diol or diaziridine; or (iii) as (i) and also an anhydride or diepoxide. The foaming agent may be water, propane, butane, pentane, trichlprofluoromethane, dichlorodifluoromethane, 1,2 - dichlorotetrafluoroethane, 1,1 - difluoro - 1 - chloroethane, dinitrosopentamethylene tetramine, ammonium carbonate, azodicarbonamide, 4,4<SP>1</SP> - oxybis - (benzene sulphon hydrazide), 2,2<SP>1</SP> - azobis - isobutyronitrile, or 4,4<SP>1</SP> - n,n<SP>1</SP>- dimethyl - n,n<SP>1</SP> - nitrosoterephthalamide.