摘要 |
A polyester film suited for optical recording media, which has a photo elasticity coefficient up to 1.2 x 10<-3> mm<2>/kgf, a surface roughness, Rt, up to 100 nm, and an average distance between surface projections, Sm, of 20 mu m or more. The film does not cause scattering or interference of light and produces no optical distortion even when heated or pressed, thus being useful as a support layer or a cover layer of optical recording media such as optical cards, optical discs, optical recording tapes, etc. |