| 摘要 |
PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film which shows a dramatically slight positional dependence of an orientation angle, as an indication of a conventional bowing phenomenon, in the center and at the end parts in the width direction of the film as well as a manufacturing method therefor. SOLUTION: During heating by a heat machine characteristics testing machine (hereafter called 'TMC') of the biaxially oriented film made of a polyester, the biaxially oriented polyester film has a time differential curwe of the expansion/contraction amount, in the width direction, of the film which shows a trace amount of a film expansion within the range of±5 deg.C of expansion temperature (Te) in the width direction and 3% or less of a factor of heat shrinkage at 150 deg.C for 10 minutes in the longer and width directions of the film. |
