Abstract: Provided is a polyester film that is excellent in stiffness and transparency, and that is suitable for producing molded articles, labels, optical films, and the like. A biaxially stretched polyester film comprises a polyester resin (I) comprising terephthalic acid and ethylene glycol as main constituent components, the polyester resin (I) having a recrystallization temperature obtained by DSC of 160° C. or more and 193° C. or less, the polyester resin (I) being contained in an amount of 60 mass % or more based on 100 mass % of the entire film, the film having a tensile modulus of elasticity of 3200 MPa or more both in a longitudinal direction and a width direction, and the total tensile modulus of elasticity in the longitudinal direction and the width direction being 7000 MPa or more.

Abstract: [Problem] To provide a cavity-containing polyester film which exhibits excellent concealability, degree of whiteness and printability, and which is still free from the occurrence of a wrinkle, distortion and the like in cases where, for example, the cavity-containing polyester film is used for a roll label, and a label is delivered therefrom or wound around a product. [Solution] A cavity-containing polyester film which comprises a layer A that internally contains a cavity, and layers B that are arranged on both surfaces of the layer A, wherein: the layer A is formed of a composition A that contains a polyester resin A and a polypropylene resin; the layers B are formed of a composition B that contains inorganic particles and a polyester resin B; and the amount of self-weight deflection of the film is from 60 mm to 100 mm at least in one direction.

Abstract: In order to provide a foldable display that is suitable for mass production and that has no risk of image distortion at its folding portion after the display is repeatedly folded, the invention provides a polyester film for foldable displays in which no cracks occurs in the folding portion. In particular, the invention provides a polyester film for a foldable display, the film having a thickness of 10-125 ?m and a high-temperature hold angle in a bending direction of 70° or more, wherein the high-temperature hold angle refers to an angle of a crease formed after fixing the film at a heating temperature of 85° C. for 18 hours in such a manner that a strain of 1.7% is applied to both surfaces of a bent portion of the film, and the bending direction refers to a direction that is orthogonal to a folding portion.

Abstract: Problem: An object of the present invention is to provide a polyester film for a foldable display, the film having a hold angle in a bending direction of 155° or more and a maximum heat shrinkage at 150° C. of 1.5% or less (wherein the hold angle refers to an angle of a crease after fixing the film at room temperature for 72 hours in such a manner that a strain of 1.7% is applied to both surfaces of a bent portion of the film, and the bending direction refers to a direction that is orthogonal to a folding portion of a foldable display produced using the film.

Abstract: Provided is a transparent conductive polyester film for a foldable display which is free of occurrence of a fold mark or a tear at a folding portion thereof to be used in a foldable display excellent in mass productivity, and free of a risk of causing distortion in an image displayed at a folding portion thereof, and a mobile device. The transparent conductive polyester film for a foldable display includes: a polyester film; and a transparent conductive layer laminated on at least one surface of the polyester film, wherein the polyester film 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/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.