| 摘要 |
PURPOSE:To obtain the titled copolymer, having specific glass transition temperature and photoelasticity constant, capable of remarkably improving CN ratio by reducing values of birefringence with excellent durability and useful as optical disks for recording information. CONSTITUTION:The aimed copolymer, obtained by bonding (A) 1-99mol.% at least two or more of 2,2-bis-(4-hydroxy-3-tertiary butyl)-2-phenylethane, 1,1,- bis-(4-hydroxy-3-tertiary butylphenyl)cyclohexane, etc., to (B) 1-30mol.% dihydric phenol, such as 2,2-bis-(4-hydroxy-3-methylphenyl)propane, through carbonate bonds and having >=130 deg.C glass transition temperature and <=60 Brewsters photoelasticity constant. The total amount of the components (A) and (B) is 100mol.%. |
