Tire innerliner comprising ester-functionalized elastomeric interpolymers of C4-C7 isomonoolefin and para-alkylstyrene

A vulcanizable tire innerliner composition comprising a mixture of:

• i) a blend of
• (A) from about 40 to 80 wt % of an elastomeric random interpolymer essentially free of halogen, comprising at least 80 wt % of a polymerized isomonoolefin containing from 4 to 7 carbon atoms and from about 0.05 up to about 20 wt % of copolymerized aromatic monomer units comprising a mixture of the following structures randomly distributed therein:
• ##STR9## wherein R and R.sup.1 are independently selected from the group consisting of hydrogen and C.sub.1 to C.sub.4 alkyl and Y comprises an ester group represented by the structure:
• ##STR10## wherein R.sub.2 and R.sub.3 are independently selected from the group consisting of hydrogen and an alkyl group containing 1 to about 6 carbon atoms and R.sub.4 is selected from the group consisting of hydrogen, an alkyl group containing from 1 to about 28 carbon atoms, an aryl group and an alkenyl group containing from 2 to about 28 carbon atoms;
• and
• (B) one or a mixture of unsaturated rubbers selected from the group consisting of natural rubber, polyisoprene, polybutadiene, butyl rubber, halogenated butyl rubber, and copolymers of butadiene with up to about 35 wt % of styrene or acrylonitrile;
• ii) from about 20 to about 45 wt % of a filler,
• iii) from 0 to about 25 wt % of a plasticizer oil;
• and
• iv) at least 1 wt % of a curing system for said interpolymer.

A process for fabricating a pneumatic tire comprised of a carcass element containing an unsaturated rubber and an innerliner element adhered to said carcass element comprising:

• a. forming a composition comprising a mixture of:
• i) a blend of
• (A) from about 40 to 80 wt % of an elastomeric random interpolymer essentially free of halogen, comprising at least 80 wt % of a polymerized isomonoolefin containing from 4 to 7 carbon atoms and from about 0.05 up to about 20 wt % of copolymerized aromatic monomer units comprising a mixture of the following structures randomly distributed therein:
• ##STR11## wherein R and R.sup.1 are independently selected from the group consisting of hydrogen and C.sub.1 to C.sub.4 alkyl and Y comprises an ester group represented by the structure:
• ##STR12## wherein R.sub.2 and R.sub.3 are independently selected from the group consisting of hydrogen and an alkyl group containing 1 to about 6 carbon atoms and R.sub.4 is selected from the group consisting of hydrogen, an alkyl group containing from 1 to about 28 carbon atoms, an aryl group and an alkenyl group containing from 2 to about 28 carbon atoms;
• and
• (B) up to 50 wt % based on the rubber content of said composition, of one or a mixture of unsaturated rubbers selected from the group consisting of natural rubber, polyisoprene, polybutadiene, butyl rubber, halogenated butyl rubber, and copolymers of butadiene with up to about 35 wt % of styrene or acrylonitrile;
• ii) from about 20 to about 45 wt % of a filler,
• iii) from 0 to about 25 wt % of a plasticizer oil;
• and
• iv) at least 1 wt % of a curing system for said interpolymer into an innerliner sheet material;
• b. exposing said sheet material to a source of high energy radiation sufficient to partially cure said sheet material;
• c. contacting said partially cured innerliner sheet material with said tire carcass element to form a laminated structure;
• and
• d. heating said structure at a temperature of from about 100.degree. to 250.degree. C. for a period of time sufficient to vulcanize said structure .