Ionic sulfonate-modified thermoplastic resins

A thermoplastic copolymer blend composition comprising blends of:

• copolymers containing from 99 to 85 wt.% of at least one vinyl monomer selected from the group consisting of styrene, alpha-methylstyrene, vinyl toluene, acrylonitrile methacrylonitrile, the lower alkyl esters of acrylic acid, and the lower alkyl esters of methacrylic acid, and from 1 to 15 wt.% of a monomer selected from the group consisting of the Group II and Group III metal salt of a copolymerizable ethylenically-unsaturated sulfonic acid monomer, with
• graft polymers containing from 5 to 95 wt.% based on final polymer of at least one vinyl monomer selected from the group consisting of styrene, alpha-methylstyrene vinyl toluene, acrylonitrile, methacrylonitrile, the lower alkyl esters of acrylic acid and the lower alkyl esters of methacrylic acid, and from 15 to 1 wt.% based on final polymer of a monomer selected from the Group II and Group III metal salt of a copolymerizable ethylenically-unsaturated sulfonic acid as grafting monomer, said grafting monomers copolymerized in the presence of from 95 to 5 wt%, based on final polymer, of a rubbery substrate polymer selected from the group consisting of polybutadiene, styrene-butadiene copolymers containing up to 50% by weight styrene, and rubbery C.sub.2 -C.sub.8 alkyl acrylate copolymers.

A method for providing processable thermoplastic resins having improved heat distortion temperature properties comprising copolymerizing 50 parts by weight of:

• A. at least one monomer selected from the group consisting of styrene, alpha-methylstyrene, vinyl toluene, acrylonitrile, methacrylonitrile, the lower alkyl esters of acrylic acid and the lower alkyl esters of methacrylic acid, and
• B. from 15 to 1% by weight, based on final copolymer, of a monovalent metal salt of an ethylenically unsaturated sulfonic acid monomer selected from the group consisting of vinyl-sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid and acryl-amidoalkyl sulfonic acids, in the presence of from 5 to 95 parts by weight of:
• C. a rubbery substrate polymer selected from the group consisting of polybutadiene, styrene-butadiene copolymers containing up to 50% by weight styrene, and rubbery C.sub.2 -C.sub.8 alkyl acrylate polymers, followed by ionexchange coagulation said resins in the presence of a metal ion selected from the group consisting of the metal ions of Group II and Group III.