US 4,377,658 AGranted

Solvent resistant polymeric composition

AssigneeShell Oil Company

InventorJames H. Collins

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Abstract

A polymeric composition having improved resistance to environmental flex cracking, solvent attack, abrasion and ozone attack comprises the blend of two different radial monoalkenyl arene-conjugated diene block copolymers, high density polyethylene, ethylene-vinyl acetate copolymer, hydrocarbon extending oil, polystyrene resin and filler.

Claims7

Dependent claims

A polymeric composition having improved resistance to environmental flex cracking solvent attack, abrasion and ozone attack consisting essentially of:

(a) 100 parts by weight of a block copolymer component selected from the group consisting of:
(i) a mixture of a radial (A B).sub.x BA first block copolymer and a radial (A' B').sub.y B'A' second block copolymer where x and y are greater than 1, the weight ratio of first block copolymer to second block copolymer is between about 20:80 and about 90:10, each block A being a monoalkenyl arene polymer block having a number average molecular weight between about 20,000 and about 40,000, each block B being an elastomeric conjugated diene polymer block having a number average molecular weight between about 15,000 and about 300,000, the blocks A comprising about 40 to about 55 percent by weight of said first block copolymer, each block A' being a monoalkenyl arene polymer having a number average molecular weight between about 5,000 and about 30,000, each block B' being an elastomeric conjugated diene polymer block having a number average molecular weight between about 15,000 and about 300,000, the blocks A' comprising about 20 to 40 percent by weight of said second block copolymer;
(ii) a radial (CD).sub.z D C third block copolymer where z is greater than 1, each block C being a monoalkenyl arene polymer block having a number average molecular weight between about 15,000 and about 25,000, each block D being an elastomeric conjugated diene polymer block having a number average molecular weight between about 15,000 and about 300,000, the blocks C comprising between about 35 and about 45 percent by weight of said third block copolymer;
and
(iii) mixtures of (i) and (ii);
(b) about 5 to about 50 parts by weight of a high density polyethylene having a melt flow index at 190.degree. C. between about 0.1 and about 30 and a specific gravity above 0.94;
(c) about 20 to about 100 parts by weight of an ethylene-vinyl acetate copolymer having a melt flow index at 190.degree. C. between about 0.1 and about 8 and a general formula ##STR2## where n ranges from about 15 to about 250 and m ranges from about 6.5 to about 40;
(d) about 25 to about 160 parts by weight of a hydrocarbn rubber extending oil;
(e) about 5 to about 30 parts by weight of a polystyrene resin selected from the group consisting of crystal polystyrene, high impact polystyrene, medium impact polystyrene and poly(alpha-methylstyrene);
and
(f) about 10 to about 60 parts by weight of a finely divided filler.

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Dependencies are inferred from the claim text.

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Abstract

A polymeric composition having improved resistance to environmental flex cracking solvent attack, abrasion and ozone attack consisting essentially of:

(a) 100 parts by weight of a block copolymer component selected from the group consisting of:
(i) a mixture of a radial (A B).sub.x BA first block copolymer and a radial (A' B').sub.y B'A' second block copolymer where x and y are greater than 1, the weight ratio of first block copolymer to second block copolymer is between about 20:80 and about 90:10, each block A being a monoalkenyl arene polymer block having a number average molecular weight between about 20,000 and about 40,000, each block B being an elastomeric conjugated diene polymer block having a number average molecular weight between about 15,000 and about 300,000, the blocks A comprising about 40 to about 55 percent by weight of said first block copolymer, each block A' being a monoalkenyl arene polymer having a number average molecular weight between about 5,000 and about 30,000, each block B' being an elastomeric conjugated diene polymer block having a number average molecular weight between about 15,000 and about 300,000, the blocks A' comprising about 20 to 40 percent by weight of said second block copolymer;
(ii) a radial (CD).sub.z D C third block copolymer where z is greater than 1, each block C being a monoalkenyl arene polymer block having a number average molecular weight between about 15,000 and about 25,000, each block D being an elastomeric conjugated diene polymer block having a number average molecular weight between about 15,000 and about 300,000, the blocks C comprising between about 35 and about 45 percent by weight of said third block copolymer;
and
(iii) mixtures of (i) and (ii);
(b) about 5 to about 50 parts by weight of a high density polyethylene having a melt flow index at 190.degree. C. between about 0.1 and about 30 and a specific gravity above 0.94;
(c) about 20 to about 100 parts by weight of an ethylene-vinyl acetate copolymer having a melt flow index at 190.degree. C. between about 0.1 and about 8 and a general formula ##STR2## where n ranges from about 15 to about 250 and m ranges from about 6.5 to about 40;
(d) about 25 to about 160 parts by weight of a hydrocarbn rubber extending oil;
(e) about 5 to about 30 parts by weight of a polystyrene resin selected from the group consisting of crystal polystyrene, high impact polystyrene, medium impact polystyrene and poly(alpha-methylstyrene);
and
(f) about 10 to about 60 parts by weight of a finely divided filler.

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