| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polyester film for a capacitor by a method in which a film having a long wet heat resisting life and a reduced dielectric loss is obtained by making surface carboxylic acid concentration a specified value or more and the glass transition temperature of a coat layer a specific value or more as compared with a conventional film, and as a result, the life under high temperature and high humidity is improved remarkably, and the capacitor is prevented from breaking by the increase in the dielectric loss. SOLUTION: In a film in which a coat is formed at least on one side of a polyester film, the surface carboxylic acid concentration of the coat is 0.003 or more, and the glass transition temperature of the coat exceeds 80 deg.C. |
