摘要 |
It is an object of the present invention to provide an optical film which has reverse chromatic dispersibility that its retardation becomes smaller as the wavelength becomes shorter and a low photoelastic constant. The optical film is made of a polycarbonate copolymer containing a unit (A) represented by the following formula: wherein R1 and R2 are each independently a hydrogen atom, hydrocarbon group having 1 to 10 carbon atoms or the like, R3 and R4 are each independently a hydrocarbon group having 1 to 10 carbon atoms or the like, “m” and “n” are each independently an integer of 0 to 4, and “p” and “q” are each independently an integer of 0 or more, and a unit (B) represented by the following formula: wherein R5 to R8 are each independently a hydrogen atom or alkyl group having 1 to 10 carbon atoms, the (A/B) molar ratio of the unit (A) to the unit (B) is 10/90 to 90/10 and which satisfies the following expression (1): R(450)<R(550)<R(650)  (1) wherein R(450), R(550) and R(650) are retardation values within the plane of the film at wavelengths of 450 nm, 550 nm and 650 nm, respectively.
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