Biaxially oriented polyester film for use as magnetic tape base - contains sub-micron particles of an oxide of at least 2 metals, esp. aluminium and silicon, to improve scratch resistance

摘要

Biaxially oriented polyester film (I) is claimed, made from a polyester contg. an aromatic dicarboxylic acid as main acid component and at least one glycol component. Film (I) contains 100-20,000 ppm of a particulate oxide cpd. (II) contg. 2 or more metals and oxygen with average prim. particle dia. 0.005-1 micron. USE/ADVANTAGE - Used esp. as base film for the prodn. of magnetic recording tape. The incorporation of (II) give polyester film with greatly increased resistance to scratching by plastic and metal guide pins during high-speed dubbing. (II) also has good affinity with the polymer and does not increase the cracking tendency of the film.