Vinyl halide polymer blends of enhanced impact resistance

Claim 2

In a vinyl halide polymer composition which is capable of being molded to an impact resistant article and which comprises a blend of a vinyl halide polymer wherein the major proportion of the monomer units are vinyl halide monomer residues and an acrylonitrile-1,3-butadiene-styrene polymeric impact modifier for polyvinyl halide, said modifier comprising (1) a mixture of a copolymer of styrene and acrylonitrile with a minor amount of a copolymer of acrylonitrile and 1,3-butadiene, or (2) a mixture of a copolymer of styrene and acrylonitrile with a minor amount of a graft of said strene-acrylonitrile copolymer onto poly-1,3-butadiene, the improvement wherein the blend also comprises a block thermoplastic elastomer wherein the major proportion of the monomer units are residues of (1) a mono-alkenyl-substituted aromatic compound of the benzene or naphthalene series of 8 to 20 carbon atoms and (2) a conjugated alkadiene hydrocarbon of 4 to 10 carbon atoms, said block elastomer being normally incompatible with said vinyl halide polymer, said vinyl halide polymer being present in a proportion of about 50 to about 99 weight percent in said blend, and said acrylonitrile-1,3-butadiene-styrene polymeric modifier and said block elastomer together being present in a proportion of about one to about 50 weight percent in said blend.

Claim 3

The composition of claim 1 wherein the alkenyl aromatic compound is a hydrocarbon of the benzene series, the acrylonitrile-1,3-butadiene-styrene polymeric modifier has about the same refractive index as said vinyl halide polymer and the weight ratio of the block elastomer to acrylonitrile-1,3-butadiene-styrene polymeric modifier is about 5:1 to about 1:5, the ratio of said alkenyl aromatic compound to the alkadiene being about 1:1 to about 1:10.

Claim 4

The composition of claim 2 wherein the units of the block elastomer are styrene and 1,3-butadiene or isoprene, the proportion of acrylonitrile-1,3-butadiene-styrene polymeric modifier and the block elastomer in the composition is in the range of about 5 to 20 weight percent based on the weight of the blend, and the weight ratio of the block elastomer to the acrylonitrile-1,3-butadiene-styrene polymeric modifier is about 4:1 to about 1:4.

Claim 5

The composition of claim 3 wherein the vinyl halide polymer is a homopolymer of vinyl chloride and the proportion of the acrylonitrile-1,3-butadiene-styrene polymeric modifier and styrene block elastomer in the composition is about 8 to about 15 weight percent based on the weight of the blend.

Claim 6

The composition of claim 4 wherein the vinyl chloride polymer is a bulk-polymerized polymer of vinyl chloride.

Claim 7

The composition of claim 5 wherein the block elastomer is a styrene-1,3-butadiene block elastomer.

Claim 8

The composition of claim 6 wherein the weight ratio of the styrene to the 1,3-butadiene in the block elastomer is in the range of from about 1:1.5 to about 1:3.

Claim 9

The composition of claim 7 wherein the block elastomer is a radial block elastomer containing styrene and 1,3-butadiene monomer residues in the weight ratio of about 1:2.3 and the weight ratio of the block elastomer to the acrylonitrile-1,3-butadiene-styrenic polymer modifier is about 1:1.

Claim 10

The composition of claim 7 wherein the block elastomer is a radial block elastomer containing styrene and 1,3-butadiene monomer residues in a ratio of about 1:1.5 and the weight ratio of block polymer to acrylonitrile-1,3-butadiene-styrene polymeric modifier is about 1:1.

Claim 11

The composition of claim 5 wherein the block elastomer is a styrene-isoprene block elastomer.

Claim 12

The composition of claim 10 wherein the block elastomer is a triblock elastomer containing styrene and isoprene monomer residues in a weight ratio of about 1:6 and the weight ratio of the block elastomer to the acrylonitrile-1,3-butadiene-styrene polymeric modifier is about 1:1.

Claim 13

An impact resistant molded article formed from the composition of claim 1.

Claim 14

An impact resistant, substantially transparent or translucent molded article formed from the composition of claim 2.

Claim 15

A vinyl halide polymer composition which is capable of being molded to an impact resistant, substantially transparent or translucent article which comprises a blend of vinyl halide polymer wherein the major proportion of the monomer units are vinyl halide monomer residues; an acrylonitrile-1,3-butadiene-styrene, polymeric impact modifier for polyvinyl halide, said modifier comprising (1) a mixture of a copolymer of styrene and acrylonitrile with a minor amount of a copolymer of acrylonitrile and 1,3-butadiene, or (2) a mixture of a copolymer of styrene and acrylonitrile with a minor amount of a graft of said styrene-acrylonitrile copolymer onto poly-1,3-butadiene and having about the same refractive index as said vinyl halide polymer; and a block thermoplastic elastomer which consists of residues of a mono-vinyl-aromatic hydrocarbon compound of the benzene or naphthalene series of 8 to 20 carbon atoms and a conjugated alkadiene hydrocarbon of 4 to 10 carbon atoms, the proportion of said vinyl-aromatic hydrocarbon residues to said alkadiene residues being in the range of from about 1:1 to 1:10, said block elastomer being normally incompatible with said vinyl halide polymer, said vinyl halide polymer said vinyl halide polymer being present in a proportion of about 50 to about 99 weight percent in said blend, and said acrylonitrile-1,3-butadiene-styrene polymeric modifier and said block elastomer together being present in a proportion of about one to about 50 weight percent in said blend, and the weight ratio of said block elastomer to said acrylonitrile-1,3-butadiene-styrene polymeric modifier being about 5:1 to about 1:5.

Claim 16

A vinyl halide polymer composition which is capable of being molded to an impact resistant, substantially transparent or translucent article which comprises a blend of vinyl halide polymer wherein the major proportion of the monomer units are vinyl halide monomer residues; an acrylonitrile-1,3-butadiene-styrene, polymeric impact modifier for polyvinyl halide, said modifier comprising (1) a mixture of a copolymer of styrene and acrylonitrile with a minor amount of a copolymer of acrylonitrile and 1,3-butadiene, or (2) a mixture of a copolymer of styrene and acrylonitrile with a minor amount of a graft of said styrene-acrylonitrile copolymer onto poly-1,3-butadiene and having about the same refractive index as said vinyl halide polymer; and a block thermoplastic elastomer which consists of residues of a mono-vinyl-aromatic hydrocarbon compound of the benzene or naphthalene series of 8 to 20 carbon atoms and a conjugated alkadiene hydrocarbon of 4 to 10 carbon atoms, the proportion of said vinyl-aromatic hydrocarbon residues to said alkadiene residues being in the range of from about 1:1 to 1:10, said block elastomer being normally incompatible with said vinyl halide polymer, said vinyl halide polymer said vinyl halide polymer being present in a proportion of about 50 to about 99 weight percent in said blend, and said acrylonitrile-1,3-butadiene-styrene polymeric modifier and said block elastomer together being present in a proportion of about one to about 50 weight percent in said blend, and the weight ratio of said block elastomer to said acrylonitrile-1,3-butadiene-styrene polymeric modifier being about 5:1 to about 1:5.