Patent attributes
The present invention is a polyester film obtained by blending 10-90 wt % of polyester (A) containing ethylene terephthalate as a main constituent component and 90-10 wt % of crystalline polyester (B) different from this polyester (A), which has a half value width of a recrystallization peak obtained by a differential scanning calorimeter (DSC) by lowering temperature of not more than 0.25. The crystalline polyester (B) is preferably a polyester selected from polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT) and polyethylene 2,6 naphthalate (PEN). According to the polyester of the present invention, a polyester film superior in mechanical characteristic and design property and having high crystallinity, which can be used alone or adhered to a metal sheet and which is free of whitening even when the film is heat treated at near or not lower than the melting point can be obtained, and further, a polyester film having such superior resistance to whitening (design property), which is not easily damaged, can be obtained.
