| 摘要 |
PROBLEM TO BE SOLVED: To optimize performances required for an optical substrate and obtain the subject inexpensive polyimide useful as a polymide substrate, etc., for optical use by specifying the glass transition temperature and the coefficient of thermal expansion. SOLUTION: This polyimide is obtained by regulating the glass transition temperature to >=300 deg.C and the coefficient of thermal expansion to >=60 ppm. Further, the above polyimide is prepared from a diamine and an acid dianhydride and preferably produced from the diamine and the acid dianhydride in which at least either one contains no fluorine. For example, the polyimide is preferably obtained by polymerizing a diamine such as 2,2'-bis(trifluoromethyl)-4,4'-aminobiphenyl with the acid dianhydride such as a tetracarboxylic dianhydride, e.g. 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, in detail the diamine with the acid dianhydride in a polar solvent, producing a polyamic acid solution and then carrying out a thermal imidation or a chemical imidation. |
