Patent ID: 8156979

Claim:
A process of preparing a tire having a built-in sealant layer which comprises building a zoned butyl rubber based sealant strip precursor into a green, unvulcanized, tire assembly curing the assembly in a suitable mold at an elevated temperature, and to at least partially depolymerize said butyl rubber of said sealant precursor zones in the presence of organoperoxides to form a tire containing a zoned built-in sealant layer; wherein said zoned built-in sealant precursor strip is comprised of a central zone and outboard lateral zones and wherein either (A) said central zone is positioned between said outboard lateral zones, wherein said outboard lateral zones are individually positioned in a spaced apart relationship to each other on each side of said central zone and at the peripheral edges of said sealant precursor strip; wherein said central zone comprises: about 50 to about 70 percent of the width of said sealant precursor strip and said lateral zones correspondingly comprise a total of from about 30 to about 50 percent of the width of the sealant precursor strip where each of said outboard lateral zones are of substantially equal widths and each individually thereby occupy from about 15 about 25 percent of the width of the sealant precursor strip; or (B) said central zone extends throughout the length and width of the sealant precursor strip and said lateral zones comprise a total of about 10 to about 20 percent of the width of the sealant precursor strip where each of the lateral zones are of substantially equal widths and each individually thereby occupy from about 5 to about 10 percent of the width of the sealant precursor strip; wherein the compositions of said sealant precursor strip zones are comprised of: (1) butyl rubber, (2) organoperoxide, (3) reinforcing filler comprised of precipitated silica and colorant having a color other than black, and (4) optionally clay; wherein the central sealant zone has a storage modulus (G′) physical property, at a 5 percent dynamic strain at 100° C. and 1 hertz in a range of from about 10 to about 60 kPa and the sealant composition for the lateral sealant zones has a storage modulus (G′) physical property, at a 5 percent dynamic strain at 100° C. and 1 hertz in a range of from about 20 to about 60 kPa and at least 20 kPa higher than the sealant composition of said central sealant zone; wherein the organoperoxide of said sealant precursor of said lateral zones is dicumyl peroxide and the organoperoxide of the sealant precursor of said central zone is comprised of n-butyl-4,4-di(tert-butyl-peroxy) valerate; wherein said zoned sealant layer is positioned between a tire innerliner rubber layer and tire rubber carcass, or between two tire innerliner rubber layers, or on an exterior surface of a tire innerliner rubber layer.