Polyester film for magnetic recording media

摘要

A biaxially oriented polyester film for use in thin metallic film-type magnetic recording media, said polyester film having a first surface to which a thin metallic film as a magnetic recording layer is to be applied and a second surface coated with an easily slippable layer composed of an organic polymeric binder and inert fine solid particles dispersed therein, the first surface having (a) large protrusions with a diameter of 0.2 to 2 micrometers and a height of 20 to 200 angstrom distributed at a density of at least 103 but less than 106 per mm2, and (b) small protrusions with a diameter of 0.01 to 0.1 micrometer and a height of 10 to 100 angstrom distributed at a density of from 106 up to 109.