Light-extraction film for EL, method for manufacturing light-extraction film for EL, and planar light-emitting body
This light-extraction film for EL includes a diffusion layer and an uneven-structure layer, the diffusion layer including first light-diffusion fine particles, and the uneven-structure layer including second light-diffusion fine particles as desired, and satisfying the expression Px−Py≧5 mass %. (Px represents the content ratio of the first light-diffusion fine particles to the total mass of the diffusion layer. Py represents the content ratio of the second light-diffusion fine particles to the total mass of the uneven structure layer.)
1. A light extraction film for EL, comprising a diffusion layer and a recessed and projected structure layer, wherein
the diffusion layer includes first light-diffusion fine particles,
the recessed and projected structure layer includes substantially no second light-diffusion fine particles,
the following Expression (1) is satisfied,
Px−Py≧ 5% by mass (1)
(Px represents a content ratio of the first light-diffusion fine particles to the total mass of the diffusion layer; and Py represents a content ratio of the second light-diffusion fine particles to the total mass of the recessed and projected structure layer),
the diffusion layer has a thickness of 40 μm or less, and
the first light-diffusion fine particles have a volume average particle diameter ranging from 1 μm to 10 μm.
2. The light extraction film for EL according to claim 1 , further comprising a base material, wherein
the diffusion layer and the recessed and projected structure layer are sequentially provided on the base material.
3. The light extraction film for EL according to claim 1 , wherein the content ratio Px of the first light-diffusion fine particles to the total mass of the diffusion layer is 10% by mass or more.
4. The light extraction film for EL according to claim 1 , wherein a thickness of the diffusion layer is 1 μm to 50 μm.
5. The light extraction film for EL according to claim 1 , wherein the content ratio Py of the second light-diffusion fine particles to the total mass of the recessed and projected structure layer is 20% by mass or less.
6. The light extraction film for EL according to claim 1 , wherein the diffusion layer has a thickness ranging from 1 μm to 40 μm.
7. The light extraction film for EL according to claim 1 , wherein the diffusion layer has a thickness ranging from 2 μm to 40 μm.
8. The light extraction film for EL according to claim 1 , wherein the first light-diffusion fine particles have an average particle diameter of 2 μm.
9. The light extraction film for EL according to claim 1 , wherein the diffusion layer includes a first resin, and the first light-diffusion fine particles included in the diffusion layer are evenly dispersed in the first resin.
10. The light extraction film for EL according to claim 9 , wherein a difference between a refractive index Rxm of the first resin and a refractive index Rxp of the first light-diffusion fine particles included in the diffusion layer is 0.05 to 0.30.
11. The light extraction film for EL according to claim 9 , wherein a difference between the refractive index Rxm of the first resin and the refractive index Rxp of the first light-diffusion fine particles included in the diffusion layer is 0.15 to 0.30.
12. The light extraction film for EL according to claim 9 , wherein the recessed and projected structure layer includes a second resin, and a refractive index Rym of the second resin is 1.40 to 1.80.
13. The light extraction film for EL according to claim 12 , wherein the refractive index Rym of the second resin is 1.55 to 1.80.
14. A surface light-emitting body comprising the light extraction film for EL according to claim 1 and an EL light-emitting element.
15. The surface light-emitting body according to claim 14 , wherein an amount of chromatic variation Δu′v′ of the surface light-emitting body is 0.01 or less.
16. A method for producing a light extraction film for EL, the method comprising:
supplying an active energy ray curable resin composition to a space between a diffusion sheet and a mold having a transferring portion of a recessed and projected structure; and
irradiating the active energy ray curable resin composition with an active energy ray,
wherein the diffusion sheet includes first light-diffusion fine particles and has a thickness of 40 μm or less, and
the first light-diffusion fine particles have a volume average particle diameter ranging from 1 μm to 10 μm.
17. The method for producing a light extraction film for EL according to claim 16 , wherein the first light-diffusion fine particles have an average particle diameter of 2 μm.