| 摘要 |
PURPOSE:To obtain a disc base having low birefringence good transparency and excellent moldability and dimensional stability by forming from a specified acid component, two specified dihydroxy compounds, and an aliphatic glycol. CONSTITUTION:A disc base made of an aromatic polyester which has a glass transition temperature of 90 deg.C or higher and is formed from terephthalic acid and/or isophthalic acid or their derivative capable of forming an ester, a dihydroxy compound of formula I having two aromatic rings and an alicyclic ring in the principal chain, a dihydroxy compound of formula II having aromatic rings and sulfur atom (s) in the principal chain, and an aliphatic glycol. In the formulas, R1 is 2-4C alkylene; R2, R3 and R5 are each H or 1-7C alkyl; R4 is a direct linkage or 1-5C alkylene; n1, n2 and n3 are each 1 or 2; R6 is 2-4C alkylene; R7 and R8 are each H or 1-7C alkyl; Y is a group containing sulfur atom (s); and n4 and n5 are each 1 or 2. |
