| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject film excellent in curl recovery, mechanical strength and dimensional stability by adding a copolyester having a mesogenic group in a main chain to a non-liquid crystalline polyester. SOLUTION: This polyester film comprises (A) a non-liquid crystalline polyester (preferably ethylene-2,6-naphthalene dicarboxylate as a main unit) and (B) a copolyester having a mesogenic group on a main chain and has >=15% curl recovering property. A copolyemerization amount of mesogenic group in the component B is preferably 5-75mol%. The component B is dispersed in a film and it is preferable that average disperse diameter of the component B is <=50nm and L/D exhibiting domain form is <=5. A copolyester comprising a unit of formula I to IV (R1 is formula V; R2 is formula VI) is preferably used as the component B. Furthermore, the component B is preferably contained in an amount of 0.5-3wt.% in the film. The haze of the film is preferably 0.1-2%. |
