| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a polylactic acid-based resin film which shows little unevenness of thickness, has excellent flatness, shows little scatter of a mechanical characteristic and an optical property in lengthwise and widthwise directions, particularly shows suppressed bowing, and shows little distribution of the characteristics in the widthwise direction of the film. <P>SOLUTION: In the method of manufacturing the biaxially stretched polylactic acid-based resin film by guiding an unstretched polylactic acid-based resin film to a longitudinal stretching process, a lateral stretching process, a heat treatment process and a relaxation treatment process in the order, the temperature of the relaxation treatment process is not lower than "Tg of the polylactic acid-based resin" to not higher than" the maximum temperature process of heat treatment ", and the following (A) and/or (B) are: (A) there is a cooling process between the lateral stretching process and the heat treatment process, and the temperature of the cooling process is not higher than "Tg+4°C of the polylactic acid-based resin; and (B) the heat treatment process is conducted in two or more zones, and regarding the relation of the two neighboring zones the temperature of the zone on the relaxation treatment process is not lower than "the temperature of the zone on the process of lateral stretching" to not higher than "the temperature of the zone on the lateral stretching process+70°C", and the temperature of the zone nearest to the relaxation treatment process is not lower than "Tg+50°C the polylactic acid-based resin" to not higher than "Tm+20°C of the polylactic acid-based resin ". This enables the polylactic acid-based resin film to be obtained which does not show suppressed bowing and has a uniform physical property in the film widthwise direction. <P>COPYRIGHT: (C)2013,JPO&INPIT |
