| 摘要 |
PURPOSE:To obtain a resin composition for a disk substrate having low hygroscopicity, superior shock resistance and heat resistance by blending an acrylic resin copolymer having a specified composition with acrylic resin having a specified composition in 95:5-70:30 ratio. CONSTITUTION:Said acrylic resin copolymer is prepd. by copolymerizing 30- 70wt% cyclohexyl methacrylate units with 10-60wt% methyl methacrylate units, 5-15wt% maleic anhydride units and 8-30wt% styrene units. Said acrylic resin is composed of the 1st rigid layer of an alkyl methacrylate (co)polymer having >=25 deg.C glass transition point, the 2nd soft layer of a copolymer whose principal component is an alkyl acrylate which gives a polymer having <=25 deg.C glass transition point when homopolymerized, and the 3rd rigid layer of a copolymer whose principal component is an alkyl methacrylate which gives a polymer having >=25 deg.C glass transition point when homopolymerized. |
