| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a retardation film by drawing a film formed from a polypropylene-based resin, wherein the variation of the retardation after manufacture is reduced. <P>SOLUTION: The method for manufacturing the retardation film includes: a longitudinal stretching process for longitudinally stretching a long original film formed from a polypropylene-based resin at a temperature Tms within a range of 110-140°C in a drawing ratio of 1.1 to 2 times; and a lateral stretching process for laterally stretching the obtained longitudinally stretched film. In the lateral stretching process, a heat retaining step of retaining the temperature of the longitudinally stretched film at a temperature Tc for 10-120 sec, a lateral stretching step of laterally stretching the longitudinally stretched film at a temperature of Tts in a drawing ratio of 3 to 6, and a thermal fixing step of thermally fixing the laterally stretched film by keeping the film at a temperature of 90-150°C for 10-120 sec are performed in this order. The temperature Tc in the heat insulating step is within±5°C of the temperature Tms in the longitudinal stretching process, and the temperature Tts in the lateral stretching step is lower than the temperature Tms in the longitudinal stretching process. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
