| 摘要 |
PCT No. PCT/JP83/00306 Sec. 371 Date Apr. 18, 1984 Sec. 102(e) Date Apr. 18, 1984 PCT Filed Sep. 14, 1983.A process for preparing biaxially stretched polyester films comprising stretching an unstretched polyester film longitudinally so that the DELTA n value becomes 0.030-0.055, further stretching the film in the same direction so that the DELTA n value does not exceed 0.08 and the &upbar& n value becomes 1.600 or less, and thereafter stretching the film transversely. The films prepared by the process of this invention are flat and slippery, less breakable and less uneven in thickness, and are especially suitable as the base film for video recording tapes.
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