Patent ID: 11926720

Abstract:
Provided is a polyester film for a touchscreen module substrate of a foldable display which is free of occurrence of a crack at a folding portion thereof, in order to provide a foldable display excellent in mass productivity, and free of a risk of causing distortion in an image displayed at a folding portion thereof after being repeatedly folded. The polyester film for a touchscreen module substrate of a foldable display satisfies the following conditions: (1) a refractive index in a bending direction is from 1.590 to 1.620; (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/cm 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.