Hard coating film for foldable display, and application of said film

A hard coating film for a foldable display, the hard coating film comprising

• a polyester film having a thickness of 10 to 80 μm,
• an easy-to-adhere resin layer, and
• a hard coating layer, the easy-to-adhere resin layer and the hard coating layer being stacked in this order on at least one surface of the polyester film,
• wherein
• the easy-to-adhere resin layer is a cured product of a composition containing a binder resin and at least one type of particles selected from the group consisting of titanium oxide particles, zirconium oxide particles, and silica particles,
• the at least one type of particles have a mean particle size of 5 to 150 nm,
• the particles in the easy-to-adhere resin layer are present in a proportion smaller in the direction of the folding portion than in the bending direction, and
• the polyester film having the easy-to-adhere resin layer stacked thereon but not yet having the hard coating layer stacked thereon satisfies the following conditions (1) to (4):
• (1) the polyester film has a refractive index in the bending direction of 1.590 to 1.620,
• (2) the polyester film has a refractive index in the direction of a folding portion of 1.670 to 1.700,
• (3) the polyester film has a refractive index in the thickness direction of 1.520 or less, and
• (4) the polyester film has a density of 1.380 g/cm3 or more,
• wherein the bending direction refers to a direction orthogonal to the folding portion of the polyester film to be folded.