Polyethylene terephthalate film for magnetic recording medium containing three different kinds of particles

Abstract

Disclosed herein is a polyethylene terephthalate film for magnetic recording medium, which contains 0.1 to 1.0% by weight based on the film of aggregated silicon oxide particles having an average particle size of 0.03 to 0.2 .mu.m, primary particle of which having an average particle size of 0.005 to 0.05 .mu.m, 0.1 to 1.0% by weight based on the film of aggregated aluminium oxide particles having an average particle size of 0.03 to 0.2 .mu.m, primary particle of which having an average particle size of 0.005 to 0.05 .mu.m and 0.005 to 0.3% by weight based on the film of a crosslinked polymer having an average particle size of 0.2 to 0.8 .mu.m, said film having a center line average surface roughness of 0.003 to 0.015 .mu.m and a sum of F-5 values in both the machine direction and the transverse direction of at least 25.0 kg/mm.sup.2. The film has a flat surface and is excellent in slipperiness, abrasion resistance, scratch resistance and protuberance resistance, which can be used as a base film for high-density magnetic recording medium.

Dependencies are inferred from the claim text.