BIAXIALLY ORIENTED LAYERED POLYESTER FILM AND MAGNETIC RECORDING MEDIUM

摘要

A biaxially oriented layered polyester film which is excellent in suitability for winding and processability while retaining the flatness of the flat surface and which gives a magnetic recording medium, especially a metal coating type high-recording-density magnetic recording medium, having excellent electromagnetic characteristics. The biaxially oriented layered polyester film comprises a second polyester layer and superposed on one side thereof a first polyester layer containing an ester of a C12 or higher aliphatic monocarboxylic acid with a polyhydric alcohol and three inert particulate materials differing in average particle diameter. In the film, one of the Young's moduli respectively in the longitudinal direction and transverse direction is 6 GPa or higher and the other is 4 GPa or higher.