Patent ID: 6962181

Claim:
A pneumatic tire having a built-in puncture sealing layer wherein said puncture sealing layer contains an at least partially organoperoxide-depolymerized butyl rubber-based sealant layer positioned between a sulfur vulcanized halobutyl rubber tire innerliner and a sulfur vulcanized diene-based vulcanized conjugated diene-based tire carcass, wherein said sealant layer is a polymeric composition having a storage modulus (G′) in a range of from about 5 to about 50, alternately about 5 to about 30, kPa, which is exclusive of polyisobutylene additive, and is comprised of, based upon parts by weight per 100 parts by weight of said partially depolymerized butyl rubber: (A) a partially organoperoxide-depolymerized butyl rubber as a copolymer of isobutylene and isoprene, wherein said copolymer prior to such depolymerization contains from about 0.5 to about 5 percent units derived from isoprene, and correspondingly from about 95 to about 99.5 weight percent units derived from isobutylene, and, based upon parts by weight per 100 parts by weight partially depolymerized butyl rubber (phr) of: (B) particulate filler comprised of about 5 to about 90 phr of rubber reinforcing carbon black and coal dust, and, optionally at least one of: (1) from zero to about 6 phr of short fibers, and (2) from zero to about 20 phr of hollow glass microspheres; (C) from zero to about 20 phr of rubber processing oil having a maximum aromatic content of about 15 weight percent; (D) from 1 to about 10 phr of liquid polyisoprene having a weight average molecular weight in a range of from about 35,000 to about 65,000.