To manufacture a polymer film excellent in optical characteristics by suppressing a shrinkage of the film in its width direction.
A cast film 15 formed from a dope 13 is peeled from a casting band 63 to form a wet film 17 and this wet film 17 is sent to a tenter type dryer 54. Both side end parts of the wet film 17 are grasped in the tenter type dryer 54. The wet film 17 is dried until brought to a predetermined solvent content while stretched in its width direction. Next, the wet film 17 is sent to a drying chamber 55 having the most upstream roller 82 as a concave roller and fed through the drying chamber 55 while applying a tension of 0.5-10 kg/m to the wet film 17 in its longitudinal direction to be dried. By this method, the film 19 reduced in wrinkles or tension due to the shrinkage in its width direction and excellent in smoothness can be obtained.
COPYRIGHT: (C)2007,JPO&INPIT
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Shigeru Iijima
Kobayashi Hideyoshi