| abstract |
An embodiment of the present invention is a composition suitable for an air barrier. The composition may include a butyl rubber, a filler, and polybuten e processing oil having a number average molecular weight of at least 400 in o ne embodiment, and a number average molecular weight of less than 10,000 in another embodiment. The filler can be such material as calcium carbonate, clay, mica, silica and silicates, talc, titanium dioxide, starch, wood flowe r, carbon black, and mixtures thereof. The viscosity of the polybutene processi ng oil is greater than 10 cSt at 100 ~C in one embodiment, and naphthenic oil i s substantially absent. The air permeability of the cured compositions of the invention ranges from 1 x 10-8 to 4.5 x 10-8 cm3 .cm/cm2.sec.atm at 65 ~C in one embodiment, and has improved aging properties suitable for use as an innerliner or innertube. |