| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyester film for a digital video tape in which the occurrence of longitudinal wrinkles with the passage of time after slit winding is prevented even when its length exceeds 20,000 m, to which high speed vacuum vapor deposition can be applied, and which is excellent in electromagnetic conversion characteristics, reduced in DO (drop out), and good in durability. SOLUTION: The polyester film includes a layer A and a layer B. The layer B contains inert particlesβ,α2, andα1 per 100 wt.% of the polyester. In the particlesβ, the content of particles at least 0.1μm and below 0.22μm in particles size is 0.2-1.6 wt.%. In the particlesα2, the content of particles at least 0.22μm and below 0.4μm in particle size is 0.01-0.7 wt.%. In the particlesα1, the content of particles at least 0.4μm and below 1.0μm in particle size is 0.0005-0.01 wt.%. The content of particlesβ,α2, andα1 in total is 0.4-2.0 wt.%. A covering layer 1.5-5 nm in arithmetic average roughness Ra and 10-60 nm in ten-point average roughness is provided on the side of the layer A. COPYRIGHT: (C)2006,JPO&NCIPI
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