| abstract |
(57) [Summary] [Constitution] An organic polymer particle having an average particle size of 0.01 μm or more and less than 0.6 μm and a particle size ratio (major axis / minor axis) of 1.0 to 1.5 is 0.01 to 2.0% by weight, and the average particle size is larger than the organic polymer particles A by 0.05 μm or more, the average particle size is 0.1 μm or more and less than 0.6 μm, and the particle size ratio is 1.0 to A polyester film containing 1.5 to 0.5% by weight of the organic polymer particles B, which is the same as or smaller than the amount of the organic polymer particles A. [Effect] It is excellent in surface flatness, slipperiness, wear resistance and winding characteristics, and can be suitably used for magnetic recording medium applications and the like. |