| abstract |
A biaxially oriented polyester film containing 0.05 to 3 wt % of agglomerates of primary particles of aluminum oxide having an average particle size of 5 to 40 nm, the agglomerates having an average particle size of 50 to 400 nm. The film of the present invention is excellent in the wear resistance against various members such as a metal pin, and suitable for various industrial purposes including a base film of a magnetic recording medium. |