| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a polyimide film for a solar cell substrate having small thermal expansion coefficient, a flexible solar cell substrate having good handleability and resistant to curling and a method for the production of the film. SOLUTION: The polyimide film for a solar cell substrate is produced by reacting a diamine component having a 4,4'-diaminodiphenyl ether/p- phenylenediamine molar ratio of 70/30 to 82/18 with an acid dianhydride component having a pyromellitic dianhydride/biphenyltetracarboxylic acid dianhydride molar ratio of 100/0 to 65/35 in an aprotic polar solvent at a diamine component/acid dianhydride component molar ratio of 100/95 to 95/100, uniformly casting the obtained polyamic acid to form a self-supporting gel film, subjecting the film to thermal or chemical dehydrative cyclization in fixed state and drawing the obtained film in the transfer direction of the film and the direction perpendicular to the transfer direction at draw ratio of 1.05-2.0 each.</p> |
