| 摘要 |
PROBLEM TO BE SOLVED: To obtain a film excellent in heat resistance, impact resistance, and retorting resistance, which film is made from a copolyester having a specified melting point, has a specified or higher glass transition temperature, has a specified or smaller difference between the highest peak temperature of the loss modulus and the glass transition temperature, and has a specified X-ray diffraction intensity ratio and a specified surface orientation coefficient. SOLUTION: There is provided a biaxially oriented film made from a copolyester having a melting point of 210-245 deg.C, wherein the glass transition temperature Tg is 78 deg.C or above, the difference between the highest peak temperature Te of the loss modulus and the Tg is below 30; the X-ray diffraction intensity ratio: I(1-10)/I(100) is 0.10-0.40, the surface orientation coefficient is 0.100-0.150, and the amount of extractives is 0.5 mg/in<2> or lower as measured by extracting the film with ion-exchanged water at 121 deg.C for 2 hr. The copolyester is obtained by reacting terephthalic acid with ethylene glycol, 2,6- naphthalenedicarboxylic acid or the like. I(1-10) and I(100) denote the X-ray diffraction intensities on the (1-10) plane and the (100) plane parallel with the film surface. |
