BIAXIALLY ORIENTED POLYESTER FILM

摘要

A biaxially oriented polyester film suited as a substrate for magnetic recording media. The film comprises a polyester and inert particles and has at least one surface with protrusions formed by the existence of the inert particles. The surface has a parameter of surface topography 2ROOT ( beta / sigma ) of 0.1 to 0.7. The average distance between adjacent protrusions is not more than 20 um and the coefficient of friction of the surface and the parameter of surface topography satisfies the following equations (1) and (2): y >/= 0.171 2ROOT ( beta / sigma ) + 0.15 (1) y