| 摘要 |
PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film hardly suffering from permanent deformation in the thickness direction of the film even under a high-temperature high-humidity condition. SOLUTION: In a first embodiment, the film deformation amount in the thickness direction is at most 6.0% of the whole thickness of the film when the film is subjected to a 24-hr transfer treatment at 40°C and 90% RH under a load of 15 MPa in the longitudinal direction. In a second embodiment, the film has a heat shrinkage factor S<SB>MD</SB>in the longitudinal direction of 0.0-1.8% at 100°C, and S<SB>MD</SB>and a creep C<SB>ZD</SB>in the thickness direction satisfy a relationship: 0≤5S<SB>MD</SB>+3C<SB>ZD</SB>≤24. COPYRIGHT: (C)2007,JPO&INPIT |
