Patent ID: 6288171
Filing Date: 2001-09-11
Classification: C08L

Abstract:
A thermoplastic vulcanizate composition, comprising;from about 20 to about 85 parts by weight of a rubber and from about 15 to about 80 parts by weight of a semi-crystalline isotactic polypropylene and a random isotactic propylene copolymer modifier, wherein said parts by weight are based upon 100 parts by weight of said rubber, said random isotactic propylene copolymer modifier, and said semi-crystalline isotactic polypropylene, wherein said semi-crystalline isotactic polypropylene consists essentially of a polypropylene homopolymer, or a polypropylene copolymer made from propylene and a mono-olefin containing 2 or 4 to 10 carbon atoms, and wherein said random isotactic propylene copolymer modifier consists essentially of from about 80 to about 95 weight percent repeat units from propylene and from about 5 to about 20 weight percent of repeat units from one or more other unsaturated olefin monomers having 2 or 4 to 12 carbon atoms based upon the weight of said random isotactic propylene copolymer, and wherein said random isotactic propylene is prepared using a metallocene catalyst system;wherein the weight ratio of said semi-crystalline isotactic polypropylene to said random isotactic propylene copolymer modifier is from about 100:2 to 100:400, wherein said semi-crystalline isotactic polypropylene has a heat of fusion of greater than 80 joules/gram, and wherein said random isotactic propylene copolymer has a heat of fusion of less than 75 joules/gram,wherein said rubber is selected from the group consisting of ethylene-propylene-diene rubber, natural rubber, butyl rubber, halobutyl rubber, halogenated rubber copolymer of p-alkylstyrene and at least one isomonoolefin having 4 to 7 carbon atoms, a copolymer of isobutylene and divinyl-benzene, a rubber homopolymer of a conjugated diene having from 4 to 8 carbon atoms, a rubber copolymer having at least 50 weight percent repeat units from at least one conjugated diene having from 4 to 8 carbon atoms and a vinyl aromatic monomer having from 8 to 12 carbon atoms, or acrylonitrile monomer, or an alkyl substituted acrylonitrile monomer having from 3 to 8 carbon atoms, or an unsaturated carboxylic acid monomer, or an unsaturated dicarboxylic acid monomer, or an unsaturated anhydride of a dicarboxylic acid, and combinations thereof,and wherein the curative to prepare the vulcanizate composition of said rubber is selected from the group consisting of a phenolic resin curative, a sulfur curative, and a hydrosilation curative.