| 摘要 |
PURPOSE:To provide an optical element, comprising a specific heat-resistant 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 resin which is a copolymer, composed of (A) 98-60wt.% methyl methacrylate unit expressed by formula I, (B) 1-30wt.% N-arylmaleimide unit expressed by formula II (R1, R2 and R3 each is H or a halogen) and (C) 1-10wt.% aromatic vinyl compound unit which is a (alpha-methyl)styrene unit or a vinyltoluene unit and having 0.2-5 ratio (DELTA/alpha) of the number of mol (DELTA) of component unit (C) to the number of mol (alpha) of the component unit (B), 0.3-1.0dl/Ag intrinsic viscosity in chloroform at 25 deg.C and <=1.5wt.% content of the residual monomers in the copolymer. |
