| abstract |
[PROBLEMS] To provide a high-quality optical film that has excellent transparency and adhesion, has an extremely small increase in cloudiness when heated, has excellent slipperiness, blocking resistance, dimensional stability, and has no noticeable interference spots. A laminated polyester film is provided. A polyester layer (A layer) containing substantially no particles is used as a base material, and a polyester layer (B layer) made of a composition containing a copolymerized polyester is laminated on both surfaces of the base material. A laminated polyester film comprising an adhesion modifying layer (C layer) made of a composition containing an adhesion modifying resin and particles on at least one surface of a layer, wherein the layer has a surface direction refractive index ((Nx (longitudinal direction refractive index)). ) + Ny (refractive index in the width direction)) / 2) is 1.57 to 1.63 and satisfies the following formulas (1), (2), and (3): (I) ° C., (II) ° C. , (III) has an endothermic melting peak at ° C. 200 <I ≦ II ≦ III <265 (1) 8 <(III-II) <35 (2) 25 <(III-I) <58 (3) [Selection] Figure 1 |