| 摘要 |
PROBLEM TO BE SOLVED: To prepare high quality biaxially oriented polyester film with improved mechanical properties such as Young's modulus and dimensional stability, which is excellent in traveling durability, shelf life and tracking resistance in floppy use as a magnetic recording medium and which is suitable for a thermal transfer ribbon or a capacitor, and to provide its preparation method. SOLUTION: A biaxially oriented polyester film comprises a polyester (A) and a polyether imide (B) and has a single glass transition temperature, wherein the diffraction peak of the crystal face in the main chain direction of the biaxially oriented polyester has a half-width in the range of 55-85 degrees in the circumference direction when the film is rotated about its normal line in crystal orientation analysis by diffractometry of wide angle X-ray diffraction. |
