| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical recording medium capable of preventing the substrate from warping by change of the environment and having a simple structure. SOLUTION: In this optical recording medium, a reflecting layer is formed on the substrate which is made of a polycarbonate resin, has embossed pits or guide grooves, and a thickness of 0.3-1.2 mm, and a transparent protecting layer having a thickness of 3-200 μm is formed on the reflecting layer, so that the optical recording medium regenerates recorded information according to change of optical intensity of the reflected light which is given by irradiating a light beam from the transparent protecting layer side. The polycarbonate resin has a main chain composed of repeating units expressed by general formula (I), end groups expressed by general formula (II) (R is a 6-20C aryl, a 5-20C alkyl or a 8-20C aralkyl; and r is an integer of 1 to 5) in an amount of at least 20 mol% based on the total end groups, a viscosity-average molecular weight of 10,000-17,000, a coefficient of water absorption of <=0.21 wt.% which is defined in ASTM-0570, and a glass transition temperature of >=130 deg.C. |
