Acrylonitrile block terpolymer barrier resins

Claim 1

The block polymeric composition resulting from the stepwise (A) polymerization of an acrylate ester or a mixture of at least 50% by weight of a diene monomer selected from the group consisting of butadiene, isoprene, chloroprene and 2,3-dimethyl-1,3-butadiene, and up to 50% by weight of a member selected from the group consisting of styrene, acrylonitrile, methacrylonitrile, an acrylic ester or a methacrylic ester, with a multi-functional sequential free-radical initiator selected from the group consisting of di[1,3-dimethyl-3-(t-butyl peroxy) butyl] peroxy dicarbonate, 2,5-dimethyl-2-t-butyl peroxy-5-hydro peroxy hexane, 1,3-dimethyl-3-(t-butyl peroxy) butyl-4-t-butyl)-azo-4-cyanovalerate, di-t-butyl-4,4'-azobis(4-cyano peroxy valerate), ##STR3## wherein n is 5 to 9 and R is alkyl, aryl or hydrogen and then (B) using some of (A) as the sole polymerization initiator copolymerizing (1) from 25 to 90% by weight of acrylonitrile and correspondingly (2) from 10 to 75% by weight of a comonomer selected from the group consisting of methyl acrylate, ethyl acrylate, the propyl acrylates, the butyl acrylates, methyl methacrylate, ethyl methacrylate, the propyl methacrylates, the butyl methacrylates, styrene, alpha-methyl styrene, indene, isobutylene, vinyl acetate, vinyl methyl ether, and vinyl ethyl ether, wherein there are employed from 5 to 30 parts by weight of (A) per 100 parts by weight of (B).