| 摘要 |
A biaxially stretched polyester film which contains a modified polybutylene terephthalate (modified PBT) and a polyethylene terephthalate (PET). The biaxially stretched polyester film is characterized in that: the mass ratio of the modified PBT to the PET, namely (modified PBT/PET) is from 20/80 to 5/95; the modified PBT is a PBT that contains 5-20% by mass of a polytetramethylene glycol unit that has a molecular weight of 600-4,000; the amount of tetrahydrofuran (THF) generated by heating the biaxially stretched film at 180°C for 30 minutes in a helium gas atmosphere is 50 μg/g or less; and the biaxially stretched polyester film has tear linearity in the longitudinal direction. |
