| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyvinyl alcohol-based film with low birefringence which corresponds to the upsizing and microfabricating of a polarizing film, and further a polyvinyl alcohol-based film which has excellent polarizing performance and achieves a polarizing film without irregular color, and a manufacturing method thereof. SOLUTION: The polyvinyl alcohol-based film with a width of 3 m or more is manufactured by a cast method, wherein retardation is within 15 nm, and a difference between the retardation of the end in the width direction and the retardation of the central part is within 5 nm. The polyvinyl alcohol-based film is preferably manufactured through (A) a process to cool a heated polyvinyl alcohol-based film to a temperature of 50°C or lower and (B) a process to heat the cooled polyvinyl alcohol-based film to 50-100°C before the film is rolled up. COPYRIGHT: (C)2007,JPO&INPIT |
