Polycarbonate resin and optical film

Abstract

Provided are a polycarbonate resin and an optical film formed therefrom, having wavelength dispersion characteristics close to the ideal broad bandwidth, excellent durable stability and flexibility, high retardation developability, a low photoelastic constant, and excellent melt processability. The polycarbonate resin comprises a unit (A) represented by the following formula, wherein Rand Reach independently represent a hydrogen atom, hydrocarbon group having 1 to 10 carbon atoms optionally containing an aromatic group, or a halogen atom, and m and n each independently represent an integer of 0 to 4: a unit (B) represented by the following formula, wherein Rand Reach independently represent a hydrogen atom, hydrocarbon group having 1 to 10 carbon atoms optionally containing an aromatic group, or a halogen atom, Rand Reach independently represent a hydrocarbon group having 1 to 10 carbon atoms optionally containing an aromatic group, s and t each independently represent an integer of 0 to 4, and p and q each independently represent an integer of 1 or more: and a carbonate unit (C) derived from an aliphatic diol compound and/or alicyclic diol compound, wherein the polycarbonate resin satisfies the following expressions (I) and (II): (I) the molar ratio of unit (A) to unit (B), (A)/(B), is 0.2 to 11.0, and (II) the molar ratio of unit (A)+unit (B) to the (A)+unit (B)+unit (C), {(A+B)/(A+B+C)}, is 0.30 to 0.60.