| 摘要 |
A biaxially oriented polyester film which has a difference between refractive index on the front side and refractive index on the rear side of the film of 0 to 0.002, a heat shrinkage factor of 0 to 0.6 % when it is heated at 105 DEG C for 30 minutes under no load, a Young's modulus of 4,609 MPa (470 kg/mm<2>) or more and a difference between the maximum value and the minimum value of Young's modulus on the film plane of 981 MPa (100 kg/mm<2>) or less, a center line average roughness on the film plane of 2 to 10 nm, and a static friction coefficient between films of 0.55 or less. A flexible disk having excellent electromagnetic conversion characteristics can be produced by forming an adhesive layer on both sides of the film and a magnetic layer on the adhesive layer. |
