| abstract |
(57) [Summary] [Purpose] Useful as a base film for magnetic recording media that has excellent abrasion resistance and scratch resistance, and that does not damage metal guides with good surface finish, metal guides with insufficient surface finish, and plastic guides. Provide polyester film. [Structure] Aluminum oxide particles having a specific surface area of 50 to 150 m 2 / g and an average particle diameter of 0.05 to 0.3 μm are contained in an amount of 0.05 to 1% by weight, and an average particle diameter of 0.3 μm. A polyester film containing at least one kind of inactive particles having a size of more than 1.2 μm and not more than 1.2 μm, wherein the aluminum oxide particles contain 3 to 30% by weight of α-type crystal form aluminum oxide. Film. |