Pneumatic tyre having built-in sealant layer and preparation thereof

Pneumatic Tyre Having Built-in Sealant Layer and Preparation Thereof Abstract In one embodiment, a pneumatic tyre (10) having a built-in sealant layer (22), before cure, includes an unvulcanized pneumatic tyre assembly (10a) having an outer circumferential rubber tread (14) and a supporting carcass (16). A precursor sealant layer (23) is situated between the supporting carcass (16) and an innermost rubber inner liner io (20). The precursor sealant layer (23) includes a non-flowing polyurethane composition that is neither gel-like nor tacky and is self-supporting. The precursor sealant layer (23), during curing of the unvulcanized pneumatic tyre assembly (10a), thermally degrades so as to provide a gel-like and tacky, self-healing polyurethane composition which defines the built-in sealant layer (22). The resulting tyre (10), with its innermost polyurethane 15 composition, allows for elimination or reduction in blister formation by reducing or elimination the amount of gases typically given off by organoperoxide-butyl based sealant layers, such as when the tyre is at its running temperature. Consequently, the thickness of the inner liner may be reduced.