| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing retardation plates capable of highly efficiently manufacturing a thin retardation plate uniformly having desired optical characteristics.SOLUTION: The method for manufacturing retardation plates includes: forming a film before drawing that has a resin layer (a) composed of a resin A having a positive intrinsic birefringence value and a resin layer (b) composed of a resin B having a negative intrinsic birefringence value; drawing the film in one direction at a temperature T1; and drawing it in the orthogonal direction at a temperature T2 lower than the temperature T1. The second drawing is a free uniaxial drawing, and a temperature TgH that is a higher temperature of a temperature Tg of the resin A and a temperature Tg of the resin B, and the temperature T2 satisfy the following relationship: T2<TgH-10. After the second drawing, tensile force of the film is reduced. The manufacturing method further includes a relaxation step of heat-treating the film at a temperature T4, in which a temperature TgL that is a lower temperature of the temperature Tg of the resin A and the temperature Tg of the resin B, and the temperature T4 satisfy the following relationship: TgL-20≤T4≤TgL. |
