| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyester film for vapor deposition suitable for obtaining a transparent vapor-deposited film excellent in oxygen and steam cutting-off properties. SOLUTION: In the transparent polyester film for vapor deposition which is a biaxially oriented polyester film 5-50μm thick, the heat shrinkage ratios of the film at 190 deg.C for 20 min in the longitudinal and cross directions are 2-6% and -0.5 to 3% respectively, a point where the gradient of a temperature- size change curve in the longitudinal direction changes from a minus value to a plus value exists, the temperature of the film at the point is at least 210 deg.C, and a size change ratio of the length of the film at the point to the original length of the film is -10 to -3%. |
