Low stress relaxation extrudable elastomeric composition
AssigneeShell Oil Company
InventorGlenn R. Himes
Life of this patent
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Abstract
An extrudable elastomeric composition includes an elastomeric polymer and a tackifying resin in which the extrudable elastomeric composition is adapted to form an elastic sheet having a stress relaxation of less than about 30 percent. The elastomeric polymer is a styrene-poly(ethylene-propylene)-styrene thermoplastic elastomeric block copolymer or a mixture of styrene-poly(ethylene-propylene)-styrene and styrene-poly(ethylene-butylene)-styrene elastomeric block copolymers. The extrudable elastomeric composition may also include a polyolefin and/or an extending oil.
Claims8
An elastomeric composition for extrusion into an elastic sheet having a stress relaxation of less than about 30 percent consisting of:
- (a) an elastomeric polymer selected from the group consisting of styrene-poly(ethylene-propylene)-styrene elastomeric block copolymer and a mixture of at least 55 parts by weight of styrene-(ethylene-propylene)-styrene block copolymers per 100 parts by weight of elastomeric polymer and styrene-poly(ethylene-butylene)-styrene elastomeric block copolymers wherein the styrene-poly(ethylene-propylene)-styrene elastomeric block copolymer has the formula:
- ##STR3## wherein m is an integer from about 38 to about 337;
- w is an integer from about 250 to about 930;
- R is selected from the group consisting of phenyl groups and substituted phenyl groups;
- x is an integer from about 2 to about 30;
- Y is coupling agent;
- and the weight ratio of polystyrene endblocks to poly(ethylene-propylene) endblocks ranges from about 10:90 to about 25:75;
- and
- (b) no less than 15% by weight and no more than 28% by weight of a tackifying resin.
An extrudable elastomeric composition for extrusion into an elastic sheet having a stress relaxation of less than about 30 percent consisting of:
- (a) from 50 to 80% by weight of an elastomeric polymer selected from the group consisting of styrene-poly(ethylene-propylene)-styrene elastomeric block copolymer and a mixture of at least 55 parts by weight of styrene-(ethylene-propylene)-styrene block copolymers per 100 parts by weight of elastomeric polymer and styrene-poly(ethylene-butylene)-styrene elastomeric block copolymers wherein the styrene-poly(ethylene-propylene)-styrene elastomeric block copolymer has the formula:
- ##STR4## wherein m is an integer from about 38 to about 337;
- w is an integer from about 250 to about 930;
- R is selected from the group consisting of phenyl groups and substituted phenyl groups;
- x is an integer from about 2 to about 30;
- Y is coupling agent;
- and the weight ratio of polystyrene endblocks to poly(ethylene-propylene) endblocks ranges from about 10:90 to about 25:75;
- and
- (b) from 3 to 25% by weight of a polyolefin.
- (c) from 15 to 28% of a tackifying resin;
- and
- (d) from 0 to 15% by weight of an extending oil.
An elastomeric composition for extrusion into an elastic sheet having a stress relaxation of less than about 30 percent consisting of:
- (a) an elastomeric polymer selected from the group consisting of styrene-poly(ethylene-propylene)-styrene elastomeric block copolymer and a mixture of at least 55 parts by weight of styrene-(ethylene-propylene)-styrene block copolymers per 100 parts by weight of elastomeric polymer and styrene-poly(ethylene-butylene)-styrene elastomeric block copolymers wherein the styrene-poly(ethylene-propylene)-styrene elastomeric block copolymer has the formula:
- ##STR5## wherein m is an integer from about 38 to about 337;
- w is an integer from about 250 to about 930;
- R is selected from the group consisting of phenyl groups and substituted phenyl groups;
- x is an integer from about 2 to about 30;
- Y is coupling agent;
- and the weight ratio of polystyrene blocks to poly(ethylene-propylene) blocks ranges from about 10:90 to about 25:75;
- and the styrene-poly(ethylene-propylene)-styrene units are chemically attached;
- and
- (b) from 15 to 28% by weight of a tackifying resin.
An extrudable elastomeric composition for extrusion into an elastic sheet having a stress relaxation of less than about 30 percent consisting of:
- (a) from 50 to 80% by weight of an elastomeric polymer selected from the group consisting of styrene-poly(ethylene-propylene)-styrene elastomeric block copolymer and a mixture of at least 55 parts by weight of styrene-(ethylene-propylene)-styrene block copolymers per 100 parts by weight of elastomeric polymer and styrene-poly(ethylene-butylene)-styrene elastomeric block copolymers wherein the styrene-poly(ethylene-propylene)-styrene elastomeric block copolymer has the formula:
- ##STR6## wherein m is an integer from about 38 to about 337;
- w is an integer from about 250 to about 930;
- R is selected from the group consisting of phenyl groups and substituted phenyl groups;
- x is an integer from about 2 to about 30;
- Y is coupling agent;
- and the weight ratio of polystyrene blocks to poly(ethylene-propylene) blocks ranges from about 10:90 to about 25:75;
- and the styrene-poly(ethylene-propylene)-styrene units are chemically attached;
- (b) from 3 to 25% by weight of a polyolefin;
- (c) from 15 to 28% of a tackifying resin;
- and
- (d) from 0 to 15% by weight of an extending oil.
Dependencies are inferred from the claim text.