| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyester film used for a coating type magnetic recording tape ensuring a superior electromagnetic conversion characteristics and error rate characteristics.SOLUTION: There is provided a base film used for a magnetism coated recording tape, which is a laminated polyester film including at least two layers of an A-layer forming a surface formed with a magnetic layer and a B-layer forming the surface of the side formed with no magnetic layer. The A-layer contains particles, an average particle diameter of which is 0.06-0.29 μm with a relative standard deviation of particle diameter being 20% or less, in an amount of 0.001-0.19 wt.%. The surface texture index of the A-layer is within a range of 80-99.99%. On the other hand, the B-layer formed with no magnetic layer contains particles, the average particle diameter of which is identical to that of the A-layer with the relative standard deviation of particle diameter being 20% or less, in an amount of 0.03-0.9 wt.% and the particle content is 1.5 times or more of that of the A-layer. |
