| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyester film that can exhibit superior electromagnetic conversion characteristics and error rate characteristics, even if using a coating-type magnetic recording tape.SOLUTION: A base film used in a coating-type magnetic recording tape being a laminated polyester film is formed of two layers of an A-layer forming the surface of a side at which at least a magnetic layer is formed and a B-layer forming the surface of a side at which the magnetic layer is not formed, the A-layer contains, at 0.001 to 0.19 wt.%, a particle whose average particle diameter is 0.06 to 0.29 μm and in which a relative standard difference of particle diameters is ≤20%, a skin index at the surface of the A-layer is within a range of 80 to 99.99%, on the other hand, the B-layer at the side at which the magnetic layer is not formed is the same as the A-layer in average particle diameter, the film contains, at 0.03 to 0.9 wt.%, a particle in which the relative standard difference of the particle diameter is ≤20%, and a content of the particle is not smaller than 1.5 times of the A-layer. |
