Pneumatic tire with built-in sealant layer composite and method of manufacturing a layer comprising polyurethane

The present invention is directed to a pneumatic tire (10) with a built-in sealant layer. The tire (10) comprises an outer circumferential rubber tread (14), a carcass (16), and an innerliner layer (22) disposed radially inwardly from the carcass (16), wherein the tire comprises a built-in sealant layer (20, 20A, 21) comprising a polyurethane based sealant material, wherein the built-in sealant layer (20, 20A, 21) is positioned between the carcass (16) and the innerliner layer (22), and wherein the built-in sealant layer (20, 20A, 21) is a multilayered composite layer, the multilayered composite layer comprising a first polyurethane layer (21), a second polyurethane layer (21 A) and an intermediate layer (20A) positioned between the first and second polyurethane layer (21, 21A). The intermediate layer (20A) comprises at least one of: (A) a non-woven microfiber layer containing polyurethane, (B) particulate pigment, (C) discrete fibers, (D) cured rubber particles, and (E) a woven microfiber layer containing polyurethane. Also, a method of manufacturing a non-woven microfiber layer containing polyurethane using as intermediate layer (20A) is disclosed.