Patent ID: 7514522

Claim:
A method for producing a polycarbonate copolymer comprising structural repeating units represented by formulas (I) and (II): wherein each of R 1 and R 2 independently represents a C1 to C6 alkyl group; X represents a single bond, a C1 to C8 alkylene group, a C2 to C8 alkylidene group, a C5 to C15 cycloalkylene group, a C5 to C15 cycloalkylidene group, —S—, —SO—, —SO 2 —, —O—, —CO—, or a group represented by formula (III-1) or (III-2): each of R 3 and R 4 independently represents a C1 to C3 alkyl group; Y represents a C2 to C15 linear-chain or branched alkylene group; a to d are independently integers of 0 to 4; and n is an integer of 2 to 450, by reacting (A) a dihydric phenol, (B) a phenol-modified diol and (C) a carbonate precursor, wherein the phenol-modified diol (B) is represented by formula (IIa) and comprises 500 ppm by mass or less of a hydroxybenzoic acid: where R 3 , R 4 , Y, c, d and n are as defined above.