| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyester film capable of providing excellent electromagnetic conversion characteristics and excellent error rate characteristics in an application to a coating type magnetic recording tape.SOLUTION: A base film includes two layers having at least an A layer and a B layer, and is applied to a coating type magnetic recording tape. The A layer forming a magnetic layer contains particles of an average particle diameter of 0.03-0.15 μm at 0.001-0.19 wt.%, and a coarse index on a surface of the A layer is in a range of 80-99.99%. The B layer not forming a magnetic layer contains particles B1 of an average particle diameter of 0.15 μm-0.25 μm at 0.01-0.3 wt.%. The number of protrusions having a height of 30 nm or more on a surface of the B layer is 0-4000 pieces/mm. |
