| 摘要 |
PURPOSE:To orientate a polyvinyl alcohol (PVA) base film uniformly and stably at a high stretching ratio, by a method wherein a PVA (derivative) film having a specified water content is rolled by press rolls in specified conditions. CONSTITUTION:A PVA (derivative) film having a water content of not more than 8% is introduced between a pair of press rolls heated to a temperature of 20-180 deg.C while applying a backward tension of at least 50kg/cm<2> to the film, and the film is rolled with a stretching ratio of at least 2 at a linear pressure of at least 100kg/cm. Accordingly, a film suitable for producing a polarizing film can be obtained. |
