Propylene copolymers in elastomeric compositions

摘要

Disclosed is an ethylene-propylene copolymer having isotactic polypropylene crystallinity compounded with a halobutyl rubber in an amount effective to improve one or more of aged tensile strength retention, fatigue resistance, and dimensional stability. Also disclosed is an elastomer composition wherein the copolymer can have at least 60 wt % propylene-derived units and at least 6 wt % ethylene-derived units, and a tire inner tube or tire innerliner composition comprising from 1 to 10 phr copolymer. Also disclosed is a vulcanizate of the elastomer composition, and articles, tire innerliners, tires, and tire inner tubes comprising the vulcanizate. Further disclosed are processes for making molded articles, tire inner tubes and tires.

主权项

1. An elastomer composition comprising a blend of:
from 70 to 100 phr of a halobutyl rubber; a cure system comprising 0.1 to 2 phr sulphur and 2 to 5 phr accelerators; and from 1 to less than 10 phr of a saturated ethylene-propylene copolymer comprising at least 60 wt % propylene-derived units, and at least 6 wt % ethylene-derived units, based on the total weight of the copolymer, wherein the copolymer has isotactic polypropylene crystallinity, a melting point equal to or less than 110° C., a heat of fusion from 5 J/g to 50 J/g, an isotactic propylene triad tacticity of from 65 to 95%, and a Mooney viscosity ML (1+4) at 100° C. in the range of 40 to 60; wherein the composition has a Mooney viscosity ML (1+4) at 100° C. less than 55.