Patent ID: 8877341

Claim:
An optical film comprising a polycarbonate consisting of two structural units represented by the following formula (1) and the following general formula (2): wherein Y is a cycloalkylene group having a carbon number of 4 through 20 or a structure represented by the following general formula (3): wherein R 1 , R 2 , R 3 and R 4 are independently a hydrogen atom or a monovalent alkyl group having a carbon number of 1 through 5, the molar ratio AB of structural unit (A) represented by the formula (1) and structural unit (B) represented by the general formula (2) is 50/50 to 30/70, a water vapor permeability is 100 g/m 2 /day/25 μm or higher and a photo-elastic coefficient is 9×10 −12 m 2 /N or lower.