Efficient mixing process for producing thermoplastic elastomer composition

Abstract

A durable, flexible, impermeable thermoplastic elastomer composition is produced using a dynamic vulcanization process conducted in a high shear mixer at elevated temperature. The composition comprises cured particles of a first halogenated isobutylene-containing elastomer and particles of a second elastomer having at least one functional group capable of reacting with and grafting to a polyamide, the particles of the first and second elastomers dispersed in a continuous thermoplastic polyamide matrix, said process comprising: (1) dispersing a curative in the halogenated elastomer and forming a pre-compounded, preferably pelletized composition; (2) introducing polyamide resin and optional stabilizers into the mixer and shearing and heating to melt the polyamide and form a mixture; (3) introducing a nylon plasticizer to reduce the viscosity of the polyamide mixture to substantially match that of the pre-compounded elastomer under mixing conditions; (4) introducing pellets of the pre-compounded elastomer into the mixer and initiating dynamic vulcanization of the elastomer and polyamide components; (5) introducing the second elastomer and continuing heating and shearing to disperse the second elastomer and substantially complete dynamic vulcanization; and delivering the thermoplastic elastomer composition from the mixer. Such compositions are particularly useful in applications such as tire innerliners and barrier films or layers.