Sealant composition

A butyl rubber based sealant composition, the butyl rubber constituent of which is present in the form of copolymers having a viscosity average molecular weight in excess of 100,000, comprising the reaction product of said butyl rubber, a curing system for said butyl rubber, a tackifier compatible with said butyl rubber and filler material composed of at least one of the group consisting of carbon black, zinc oxide, aluminum hydrate, lithopone, whiting, clays, hydrated silicas, calcium silicate, silicoaluminates, magnesium oxide and magnesium carbonate, the composition being compounded such that it has a tensile strength of at least 30 psi, an elongation of at least 600% and a cross-link density such that its swell ratio in toluene is between 12 and 40.

A butyl rubber based sealant composition the butyl rubber constituent of which is present only in the form of copolymers having a viscosity average molecular weight in excess of 100,000 comprising the reaction product of said butyl rubber, a quinoid cross-linking agent for the butyl rubber, a cross-linking activator at least one tackifier compatible with butyl rubber and a filler material, said filler material including at least 2 parts by weight of carbon black per hundred parts butyl rubber, the composition being compounded such that it has a tensile strength of at least 30 psi, an elongation of at least 600% and a cross-link density such that its swell ratio in toluene is between 12 and 40, and such that the elongation is sufficiently high and the cross-link density sufficiently low that, when the sealant is applied to the interior of a tire, the tire is punctured by a plurality of nails which are repeatedly deflected for a period of one minute and then withdrawn, and the tire is inflated to 32 psig, the sealant seals at least 80% of the punctures.