Optical film and optical compensatory film, polarizing plate and liquid crystal display using same

An optical film comprising a polycarbonate copolymer, the polycarbonate copolymer comprising a repeating unit represented by formula (A) and a repeating unit represented by formula (B), the repeating unit represented by formula (A) amounting to 30 to 80 mol % of the polycarbonate copolymer, the optical film satisfying formulae (1) to (4):

• 0.1<Re(450)/Re(50)<0.95 (1)
• 1.03<Re(650)/Re(550)<1.93 (2)
• 0.4<(Re(450)/Rth(450))/(Re(550)/Rth(550))<0.95 (3)
• 1.05<(Re(650)/Rth(650))/(Re(550)/Rth(550))<1.90 (4)
• wherein Re(λ) represents an in-plane retardation value by nm of the optical film for a light having a wavelength of λ nm, and Rth (λ) represents a retardation value by nm in a thickness direction of the optical film for a light having the wavelength of λ nm;
• wherein R1 to R8 each independently represents an at least one group selected from the group consisting of a hydrogen atom, a halogen atom and a hydrocarbon group containing from 1 to 6 carbon atoms, and X represents formula (X):
• wherein R9 and R10 each independently represents a hydrogen atom, a halogen atom or an alkyl group containing from 1 to 3 carbon atoms;
• wherein R11 to R18 each independently represents an at least one group selected from the group consisting of a hydrogen atom, a halogen atom and a hydrocarbon group containing from 1 to 22 carbon atoms, and Y represents a group selected from the following groups:
• wherein R19 to R21, R23 and R24 each independently represents at least one group selected from the group consisting of a hydrogen atom, a halogen atom and a hydrocarbon group containing from 1 to 22 carbon atoms, R22 and R25 each independently represents an at least one group selected from the group consisting of hydrocarbon groups containing from 1 to 20 carbon atoms, and Ar1 to Ar3 each independently represents at least one group selected from the group consisting of aryl groups containing from 6 to 10 carbon atoms.