Laminate polyester films

Abstract

A stretch-oriented laminate polyester film consisting of two or three layers of polyester films; both polyester film A and polyester film B which form the external layers of the laminate film are composed of a polyester having an intrinsic viscosity of 0.35 to 1.0, wherein the intrinsic viscosity of a polyester forming the polyester film B is 0.02 to 0.5 greater than that of a polyester forming the polyester film A. The laminate film is curled in the widthwise direction with the polyester film B located inwardly of the curl. This film can be used for various applications, especially as a measuring tape, an adhesive tape and a base of a photographic film. As a preferred embodiment, a laminate polyester magnetic tape with reduced drop-out occurrence, comprising the stretch-oriented laminate film and a magnetic layer coated on one external layer thereof, the polyester film A forming one external layer of the laminate film having incorporated therein a finely-divided inert compound so that its coefficient of static friction becomes not more than 0.80, and the polyester film B forming the other external layer of the laminate film being a film having a coefficient of static friction greater than that of the polyester film A by at least 0.05 and a smoother surface, with the magnetic layer being coated on the surface of the polyester film B is disclosed.

Dependencies are inferred from the claim text.