| abstract |
The film of the present invention can provide a polyethylene terephthalate film which is suitable for use in, for example, a substrate film for a flexible device, which can reduce dimensional changes in each step, has small curl, and is excellent in workability. Substrate film. The biaxially oriented polyethylene terephthalate film of the present invention has a degree of crystallinity (Xc) of more than 0.35 and less than 0.50, and the intrinsic viscosity (IV) of the resin constituting the film is 0.66 to 1.0 dl/g, and the film The thermal expansion coefficients of the long-side direction and the film width direction at a temperature of 50 to 170 ° C are 0 to 29 ppm / ° C, respectively, and the thermal shrinkage rates of the film in the longitudinal direction and the film width direction of 180 ° C are -0.5% to 1.0%, respectively. |