BIAXIALLY ORIENTED LAMINATE POLYESTER FILM FOR MAGNETIC TAPE

摘要

PROBLEM TO BE SOLVED: To provide a biaxially oriented laminate polyester film useful for a magnetic tape having stable travelling property and excellent magnetic output property, particularly a magnetic tape of digital recording system. SOLUTION: In a biaxilly oriented laminate polyester film, a polyester layer A which contains 0.01-2wt.% of fine particle is laminated on one face of a polyester layer B. The whole thickness of the film is 8μm or ratio (t/d) between a thickness t(μm) of the polyester layer A and an average particle diameter d(μm) of fine particle in the layer is 5-30, and a ratio (μkA/μkB) between a friction coefficientμkA of the surface of the polyester layer A to metal and a friction coefficientμkB of the surface of the polyester layer B to metal is 1.2-4.0.