| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical material for light transmission having high transparency, heat resistance and flaw resistance and being especially useful as an optical film having highly optimized low birefringence (optical isotropy). <P>SOLUTION: The material consists of a copolymer having (i) an unsaturated alkyl carboxylate unit and (ii) a glutaric acid anhydride unit of formula (1) (wherein R<SP>1</SP>and R<SP>2</SP>may be the same or different and are each a hydrogen atom or a 1-5C alkyl group), a copolymer having (i) the alkyl ester unit, (ii) the anhydride unit of formula (1) and (iii) an unsaturated carboxylic acid unit, or a copolymer having (i) the alkyl ester unit, (ii) the anhydride unit, optionally (iii) the carboxylic acid unit and (iv) other vinyl type monomer unit(s) which has an absolute value of birefringence of 1.0×10<SP>-4</SP>or lower. <P>COPYRIGHT: (C)2004,JPO |
