Polyester carbonate copolymer for optical lens and optical lens

摘要

This invention is to provide a polyester carbonate copolymer suitable for an optical lens that has high refractivity and transparency and low birefringence and little optical strain, and optical lenses formed therefrom. This invention is 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.