| 摘要 |
PURPOSE:To obtain a methacrylate copolymer which is lowly birefringent and improved in shape stability, low hygroscopicity, heat resistance and transparency by copolymerizing an N-substituted maleimide with a specified methacrylic ester and methyl methacrylate. CONSTITUTION:5-30 wt.% N-substituted maleimide (e.g. N-ethyl-maleimide) is copolymerized with 15-40 wt.% methacrylic ester having a 7C or higher alicy clic hydrocarbon group as the ester moiety (e.g. norbonyl methacrylate) and 80-40 wt.% methyl methacrylate and 0-10 wt.% copolymerizable unsaturated monomer which can give a homopolymer with a glass transition temperature of 40 deg.C or higher (e.g. methyl acrylate) at 0-200 deg.C in the presence of 0.01-10 wt.%, based on the total weight of the monomers, polymerization initiator (e.g. benzoyl peroxide) to obtain a methacrylate copolymer with a weight- average mol. wt. of 10,000-1,000,000, a glass transition temperature of 110 deg.C or above, a bending modulus of 30,000 kg/cm<2> or more and a saturated moisture absorption of 1.6 wt.% or below. |
