Patent ID: 7879272

Claim:
A process for producing an oriented thermoplastic elastomer film having reduced oxygen permeability and improved fatigue resistance and a planar birefringence (PBR) value defined by: PBR=[(n1+n2/2)−n3 wherein n1, n2 and n3 are refractive indices along the machine direction, the transverse direction, and the film normal direction, respectively, of equal to or greater than 0.002, by means of dynamic vulcanization of a blend of (A) a halogenated isobutylene elastomer and (B) polyamide, comprising: i) pretreating the isobutylene elastomer with zinc oxide; ii) pelletizing the thus treated isobutylene elastomer; iii) subsequently mixing the pelletized isobutylene elastomer with the polyamide under dynamic vulcanization conditions to produce a polymer mixture; and iv) casting or extrusion blowing said polymer mixture under conditions of a shear rate to control the molecular arrangement of the polyamide in the film to obtain said film.