| 摘要 |
PURPOSE:To provide an optical element, comprising a specific heat-resistant copolymer resin having a specified viscosity and a specific content of the residual monomers, excellent in heat resistance, low hygroscopicity, surface properties and processability, capable of manifesting a high refractive index and useful as various lenses, substrates, etc., for optical disks. CONSTITUTION:This optical element comprises a heat-resistant copolymer resin which is a copolymer, composed of (A) 99-70wt.% methyl methacrylate unit expressed by formula I and (B) 1-30wt.% N-arylmaleimide unit expressed by formula II (R1, R2 and R3 each is H or a halogen), having 0.3-1.0dl/g intrinsic viscosity in chloroform at 25 deg.C, <=1.0wt.% content of the residual methyl methacrylate in the copolymer and <=0.3wt.% content of the residual N- arylmaleimide therein. |
