Abstract: A thermosetting resin composition having improved properties as an electrical insulating material and being particularly suited for use in printed circuit boards, consists essentially of an acryloyloxyl- or methacryloyloxyl- terminated butadiene homopolymer or copolymer, for example, with acrylonitrile or styrene, an ethylenically unsaturated monomer capable of copolymerizing with the terminating acryloyloxyl or methacryloyloxyl groups of the butadiene homopolymer or copolymer, and an acid anhydride containing at least one ethylenically unsaturated group in its molecule. In preferred compositions of the invention, there are from 1.5 to 3.0 terminating acryloyloxyl or methacryloyloxyl groups per molecule of the butadiene homopolymer or copolymer, and the amounts of the ethylenically unsaturated monomer and of the acid anhydride are from 50 to 200 weight percent and from 5 to 20 weight percent, respectively, based on the weight of the terminated butadiene homopolymer or copolymer.

Abstract: A flame retardant thermosetting resin composition having improved properties as an electrical insulating material and being particularly suited for use in printed circuit boards composed essentially of acryloyloxy- or methacryloyloxy-terminated butadiene homopolymer or butadiene copolymer with, for example, acrylonitrile or styrene, ethylenically unsaturated monomer capable of copolymerizing with the terminating acryloyloxy- or methacryloyloxy- groups of the butadiene homopolymer or copolymer, which monomer has a substantial amount of haloaryl, and acid anhydride having at least one ethylenically unsaturated group. In preferred compositions of the invention, there are from 1.5 to 3.