Patent ID: 8378055

Claim:
A polyester carbonate copolymer for an optical lens, which comprises 67 to 95 mol % of a unit of the following formula (I) and 33 to 5 mol % of a unit of the following formula (II) and has a specific viscosity of 0.12 to 0.30, wherein Y in the formula (II) is a phenylene group or a naphthalenediyl group, and when Y in the formula (II) is a 2,6-naphthalenediyl group, the copolymer comprises 82 to 95 mol % of the unit of the formula (I) and 18 to 5 mol % of the unit of the formula (II), and when Y in the formula (II) is a 1,4-phenylene group or a 1,3-phenylene group, the copolymer comprises 75 to 82 mol % of the unit of the formula (I) and 25 to 18 mol % of the unit of the formula (II).