| 摘要 |
PURPOSE:To provide the subject film comprising a polymide, polyimide copolymer or polyimide mixture as a main structural element, having excellent transparence and thermal resistance and useful for optical equipments, etc. CONSTITUTION:The objective film contains as a main structural element a polyimide, polyimide copolyimide or polyimide mixture having repeat units of the formula (R1 is a tetravalent organic group). The film is prepared by reacting a tetracarboxylic acid dianhydride (e.g. pyromellitic dianhydride) with a diamine [e.g. 2,2'-(bistrifluoromethyl)-4,4'-diaminobiphenyl] in a polar organic solvent such as N-methyl-2-pyrrolidone, casting the prepared polyamic acid on the surface of a flat plate such as a glass plate and subsequently heating the film at 250-350 deg.C. |
