Reinforced plastic from an open cure technique with a graft polymer

A graft polymeric material is made by polymerizing in a reaction diluent and in the presence of a free-radical catalyst a mixture comprising a liquid polymer of a C4-C6 diolefine, an ethylenically unsaturated monomer and a monomer having at least two ethylenic linkages. Diolefine polymers specified are those of butadiene, isoprene, dimethylbutadiene, hexadiene, piperylene and methyl pentadiene, in which may be present minor amounts of other copolymerized monomers, e.g. styrene, p-methyl styrene, dimethyl styrene, acrylonitrile and methyl vinyl ketone. Ethylenically unsaturated monomers specified are styrene, vinyl toluene, halostyrenes, vinylnaphthalenes, alkyl acrylates, methacrylates and fumarates, vinyl and vinylidene chlorides, acrylonitrile, diallyl phthalate and triallyl cyanurate. As monomers having at least two ethylenic linkages there may be used divinyl benzene, naphthalene, toluene and xylene and trivinylbenzene. Free-radical catalysts specified are p dicumyl peroxide, ditert.-butyl peroxide, ditert.-butyl perphthalate, benzoyl peroxide and azo compounds. As reaction diluents there are specified toluene and a close-cut naphtha. The resulting graft polymers may be used to impregnate a reinforcing element, e.g. paper, cloth, &c. to produce a laminate which may be cured by heating at temperature above 250 DEG F.