| 摘要 |
PROBLEM TO BE SOLVED: To improve slipperiness, running properties and abrasion resistance by a method wherein a polyester A layer for which deposit particles containing calcium and phosphorus and inactive particulates are specified is laminated on a polyester B layer and the ratio of the Young's modulus in the lateral and longitudinal directions of a film, the root-mean-square roughness, mean roughness and maximum roughness of the surface of the polyester A layer are made to be in specified ranges. SOLUTION: A polyester A layer contains deposit particles containing calcium and phosphorus and having a mean particle size of 0.7-1.5μm by 0.01-0.1 wt.%, inactive particulates having a mean particle size of 0.1-1.0μm by 0.1-1.0 wt.% and inactive particulates having a mean primary particle size of 0.3μm or below and a Mohs hardness of 7 or above by 0.01-1.0 wt.%. The ratio between the Young's modulus YTD in the lateral direction of a film and the Young's modulus YMO in the longitudinal direction thereof is expressed by the formula. Besides, the root-mean-square roughness of the surface of the polyester A layer is made to be in the range of 0.010-0.025 pm, the mean surface roughness thereof in the range of 0.005-0.020μm and the maximum roughness thereof in the range of 0.200-0.350μm.
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