| 摘要 |
PURPOSE:To obtain a lightweight optical recording disk having high rigidity, hardly causing surface wobbling and preventing the occurrence of a focusing error by using cyclic polyolefin having a specified structure as a substrate and glass as a protective substrate. CONSTITUTION:A substrate is formed with cyclic polyolefin having repeating units represented by the structural formula and a protective substrate is formed from glass to obtain a lightweight optical recording disk having high rigidity, hardly causing surface wobbling even at the time of high-speed rotation and capable of preventing the occurrence of a focusing error. In the formula, q is 0 or a positive integer and each of R1 and R<2> is H, halogen, a hydrocarbon residue, ester, nitrile or a heterocyclic residue. |
