| 摘要 |
The invention provides a method for longitudinally stretching a thermoplastic resin film, by which a wrinkle or a scratch is not formed during longitudinally stretching a thermoplastic resin film and the retardation at a desired level can be developed, as well as a longitudinally stretched film produced by the method. A thermoplastic resin film is drawn with a pair of rolls (34a and 36a) rotating at different circumferential velocities to stretch the film longitudinally, thereby a temperature inside a heating oven (32) installed between the pair of rolls (34a and 36a) is set between Tg of the thermoplastic resin film (12)+50° C. and Tg+140° C., and the thermoplastic resin film (12) is stretched in the heating oven (32) over a heating time of 1 sec or longer and 100 sec or shorter.
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