Patent ID: 6800697
Filing Date: 2004-10-05
Classification: C08J,C08L,G02B

Abstract:
A method for producing a retardation film, which comprises the steps of mixing mutually compatible polymers A and B which satisfy the following conditions (1) and (2), and of forming the resulting mixture into a film, wherein the mixing ratio is adjusted to adjust the ratio R(450)/R(550) for the mixture of the polymers A and B:(1) the polymer A is a copolymer comprising repeating units a and b, and (2) the polymer B is a copolymer comprising the repeating units a and b and is different from the polymer A in copolymerization composition and in the ratio R(450)/R(550), wherein the following formula (1) is satisfied for the retardation film: R(450)/R(550)<1â€ƒâ€ƒ(1) wherein R(450) and R(550) are each the retardation in the film plane of the retardation film measured at measuring wavelengths of 450 nm and 550 nm and R(450)/R(550) is their ratio.