| abstract |
To provide a white film excellent in film forming property, whiteness, reflectivity, lightness and light resistance, and to provide a surface light source excellent in luminance characteristics by using the white film. A polyester film comprising a polyester resin (A), an amorphous cycloolefin copolymer (B) and inorganic particles (C), the content of the amorphous cycloolefin copolymer (B) Is 3 wt% or more and 15 wt% or less with respect to the polyester film, and the content of the inorganic particles (C) is 8 wt% or more and 20 wt% or less with respect to the polyester film. The glass transition temperature (Tg) of the copolymer (B) is 180 ° C. or higher, and the amorphous cycloolefin copolymer (B) is dispersed in the film at a volume average dispersion diameter of 1.5 μm or less. White monolayer having voids with amorphous cycloolefin copolymer (B) as a core and having a specific gravity of 0.55 to 0.99 Li ester film. [Selection figure] None |