| 摘要 |
PROBLEM TO BE SOLVED: To provide a laminated polyester film having a good yield in a processing process and useful as a base film excellent in electromagnetic conversion characteristics when used for the production of a magnetic resin medium. SOLUTION: The laminated polyester film comprises a polyester layer A containing no particles, the polyester layer B, which contains 0.05-1 wt.% of inert particles with a mean particle size of 150-500 nm, formed on one surface of the polyester layer A and the coating film layer C which has a surface center average roughness (WRaC) of 0.1-4 nm, applied to the other surface of the polyester layer A. The heat shrinkage factors in the longitudinal and lateral directions of the film is 1.5-5.0% and 1.0-3.0% and the ratio of bath 0.8-5.0 at 150°C and 0.5-1.5% and 0.2-1.0% and the ratio of bath 1.0-5.0 at 105°C, and the Young's moduli in the longitudinal and lateral directions of the film are 4,500-7,000 N/mm<SP>2</SP>and 4,000-6,000 N/mm<SP>2</SP>and the ratio (Ym/Yt) of both of them is 0.8-1.75. COPYRIGHT: (C)2004,JPO
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