| 摘要 |
PURPOSE:To form an optical disc base with a large carrier to noise ratio (C/N ratio) when recording is reproduced and excellent heat resistance and mechanical strengths even when manufactured by injection molding, by using a resin compsn. consisting of an arom. vinyl polymer part and a polyphenylene oxide part. CONSTITUTION:An optical disc base obtd. by injection-molding a resin compsn. consisting of 50-70 pts.wt. polymer part wherein an arom. vinyl monomer is a main constituting unit and 50-30 pts.wt. polyphenylene oxide part. This base satisfies the conditions of ¦Nx-Ny¦<=2X10<-5>; ¦Nx-Nz¦<=2X10<-4>; ¦Ny-Nz¦<=2, wherein Nx is a mean refractive index in the radical direction of the base, Ny is that in the perpendicular direction to the face of the base and Nz is that in the direction perpendicular to those of Nx and Ny. |
