| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polyimide having a high light transmission without detriment to its heat resistance by subjecting 2,3,3',4'-biphenyltetracarboxylic dianhydride and a diamine to polymn. and imidization. SOLUTION: A diamine component mainly comprising a diamine of formula I (wherein R is a 4-16C linear or branched aliph. hydrocarbon group)(e.g. 1,1- diaminohexane) and contg. an arom. diamine, etc., is dissolved in an org. solvent (e.g. N-methyl-2-pyrrolidone), and the resultant soln. is mixed with an acid dianhydride component mainly comprising a carboxylic dianhydride of formula II (e.g. 2,3,3',4'-biphenyltetracarboxylic dianhydride) and contg. other tetracarboxylic dianhydrides. The resultant mixture is subjected to polynm. and imidization under heating and then put into a poor solvent to precipitate the resultant polymer, thus giving a polyimide of formula III (wherein R is the same as in formula I) which has a logarithmic viscosity (30 deg.C) of 0.3-2 and gives a 20μm-thick film having a Y1 of 5 or lower and a light transmission of 60% or higher at 400 nm and 85% or higher at 500 nm. |
