| 摘要 |
PURPOSE:To hold high shape accuracy even in an environmental change at the time of practically using the rotary polygon mirror by forming the polygon mirror by specific cyclic olefin group random copolymer or a cyclic olefin group ring-opened polymer. CONSTITUTION:A mirror face 3 is formed on the surface of a resin molded product 2 to be a polygon. The resin molded product 2 is formed by cyclic lefin group random copolymer consisting of cyclic olefin having 005 to 10dl/g limiting viscosity measured by decalin at 135 deg.C and expressed by the shown structural formula, cyclic olefin ring-opened polymer expressed by the shown formula I, or its hydrogen additive. In the formula, (n) is '0' or '1', (m) is '0' or a positive integer, and R<1> to R<19> indicate atoms or radicals selected from a group selected from hydrogen atoms, halogen atoms, and so on. Consequently, high humidity and heat resistance can be obtained and high shape accuracy can be held even in an environmental change at the time of practically using the rotary polygon mirror. |
