Biaxially oriented polyester film

摘要

A biaxially oriented polyester film of a polyester composed of an aromatic dicarboxylic acid as a major acid component and at least one glycol component, said polyester film containing 100-20000 ppm of a particulate compound oxide composed of two or more metals (selected from Al, B, Si, Ti, Zr, W, and Fe) and oxygen whose average primary particle diameter is 0.005-0.1 mu m. The compound oxide contains 0.1-5 wt % by weight of chlorine. The polyester film finds use as a base film for magnetic tape with improved scratch resistance.