Optical member, and backlight unit and image display device using said optical member

An optical member, comprising:

• a light guide plate having an end surface that light from a light source enters and an emitting surface from which the entered light is emitted;
• and
• a reflective plate bonded to a side of the light guide plate opposite to the emitting surface via a double-sided pressure-sensitive adhesive film,
• wherein the double-sided pressure-sensitive adhesive film includes a first pressure-sensitive adhesive layer, a low-refractive index layer, and a second pressure-sensitive adhesive layer from a light guide plate side,
• wherein the optical member further comprises a surface-treated layer formed on a side of the reflective plate opposite to the double-sided pressure-sensitive adhesive film,
• wherein the surface-treated layer has a dynamic friction coefficient of 1.0 or less,
• wherein the low-refractive index layer is formed of one or a plurality of kinds of constituent units each forming a fine pore structure, and the constituent units are chemically bonded to each other through a catalytic action,
• wherein the low-refractive index layer has pores therein and the porosity of the low-refractive index layer is 40% or more and 85% or less,
• wherein a size of each of the pores in the low-refractive index layer is from 2 nm to 500 nm,
• wherein the low-refractive index layer has a refractive index of 1.30 or less, has a haze of less than 5%, and has a thickness of from 0.2 μm to 5 μm,
• wherein the first pressure-sensitive adhesive layer is adjacent to the low-refractive index layer and has a storage modulus of elasticity of from 1.3×105 (Pa) to 1.0×106 (Pa), and
• wherein the second pressure-sensitive adhesive layer has a storage modulus of elasticity of from 5.0×103 (Pa) to 9.0×104 (Pa).