CPC C08J 5/18 (2013.01) [G02B 3/0087 (2013.01); G06F 1/1652 (2013.01); G06F 3/0412 (2013.01); C08J 2367/00 (2013.01); G06F 2203/04102 (2013.01)] | 13 Claims |
1. A polyester film for a touchscreen module substrate of a foldable display, the polyester film satisfying the following conditions:
(1) a refractive index in a bending direction is from 1.591 to 1.606;
(2) a refractive index in a folding portion direction is from 1.670 to 1.700;
(3) a refractive index in a thickness direction is 1.520 or less; and
(4) a density is 1.380 g/cm3 or more,
wherein the bending direction refers to a direction orthogonal to a folding portion of the polyester film at a time when the polyester film is folded,
wherein the polyester film is a biaxially stretched polyethylene terephthalate film, and
wherein the polyester film comprises an easy-to-adhere layer on at least one surface thereof and a hard coating layer having a thickness of from 1 μm to 50 μm.
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