| 摘要 |
PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film excellent in high output characteristics especially as a film for digital video and high density data. SOLUTION: A biaxially oriented polyester film has at least a two-layered structure and at least one outermost layer thereof mainly comprises poly(ethylene-2,6-naphthalene dicarboxylate). In this case, the particle content of this layer is 0.05-3 wt.%, the number of surface projections thereof is 3,000-15,000,000/mm2, the glass transition temp. thereof is 125-155 deg.C and the stiffness amorphous quantity thereof is 10-55%. Since the polymer characteristics and the number of surface projections of at least one outermost layer are specified, excellent output characteristics can be obtained and sufficiently good characteristics as a high density magnetic recording medium can be also obtained.
|
