| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical disk substrate hardly suffering from warpage and wobbling which is formed of a specific polycarbonate resin excellent in low water absorption, flexural modulus of elasticity, flowability and heat resistance and having a small photoelastic constant. <P>SOLUTION: The optical disk substrate is formed of an aromatic polycarbonate resin which comprises an aromatic dihydroxy component, at least 20 mole% of the total amount thereof being 9,9-bis(3-methyl-4-hydroxyphenyl)fluorene, further comprises 0.01-0.2 mole%, based on the total amount of the aromatic dihydroxy component, of a trifunctional or higher-functional phenolic compound as a copolymerization component and satisfies (A) a glass transition temperature of 120-180°C, (B) a water absorption of at most 0.1 wt.% after immersion in water at 23°C for 24 hours and (C) a flexural modulus of elasticity of 2,800-4,000 MPa. <P>COPYRIGHT: (C)2003,JPO |
