Curable sealant two-component composition containing butyl rubber derived from isoolefin and open-chain conjugated diolefin

Claim 1

A curable and solventless sealant composition consisting essentially of a mixture of (a) a mixture of about 100 parts low molecular weight elastomeric isocyanate terminated prepolymer, said prepolymer having from about 3.5 to about 4.5% NCO content, from about 250 parts to about 400 parts medium process oil, said oil having a Brookfield viscosity at 22° C. of about 10 to 500 cps, and from about 50 parts to about 70 parts low molecular weight uncured butyl rubber having a Staudinger molecular weight of 5,000 to 15,000, and, (b) a mixture of from about 150 parts to about 250 parts low molecular weight polyol having a molecular weight of from 400 to 5,000, said polyol having about 0.8 milliequivalent per gram hydroxyl, from about 40 to about 65 parts low molecular weight uncured butyl rubber having a Staudinger molecular weight of 5,000 to 15,000, from about 225 to about 275 parts of a medium process oil as in (a) and from about 0.1 to about 10.0 parts catalyst for the reaction of said prepolymer and said polyol, said (a) and said (b) being mixed together in a volume ratio of from about 1.0 to 1.0.