Light diffusion film and light diffusion film manufacturing method

Patent metadata

Field	Value
Publication number	US-10288779-B2
Application number	US-201715685311-A
Country	US
Kind code	B2
Filing date	Aug 24, 2017
Priority date	Mar 29, 2013
Publication date	May 14, 2019
Grant date	May 14, 2019

Abstract

Provided are a light diffusion film having a single-layered light diffusion layer, in which the uniformity of the intensity of diffused light in the light diffusion angle region can be increased, or the light diffusion angle region can be expanded effectively, by regulating the combination of the angles of inclination of pillar-shaped objects in plural columnar structure regions, and a method for manufacturing a light diffusion film. Disclosed is a light diffusion film having a single-layered light diffusion layer, the light diffusion film having a first columnar structure region and a second columnar structure region, in which plural pillar-shaped objects having a relatively high refractive index are arranged to stand close together in a region having a relatively low refractive index, sequentially from the lower part of the film along the film plane.

First claim

The invention claimed is:

1. A light diffusion film comprising a single-layered light diffusion layer including, sequentially from the lower part of the film along a film thickness direction, a first columnar structure region and a second columnar structure region, in which plural pillar-shaped objects having a relatively high refractive index are arranged to stand close together in a region having a relatively low refractive index,
the light diffusion film being a photo cured product of a composition for a light diffusion film, and
wherein the light diffusion film comprises an overlapping columnar structure region in which an upper end of the first columnar structure region extends into a lower end of the second columnar structure region so that the upper end of the first columnar structure region and the lower end of the second columnar structure region overlap with each other in a cross section of the light diffusion film when the light diffusion film is cut at a plane that is perpendicular to a light diffusion film plane and cuts the pillar-shaped objects into two along axial lines in the first columnar structure region.

2. The light diffusion film according to claim 1 , wherein the overlapping columnar structure region is formed by tips of anyone side of the pillar-shaped objects respectively originating from the first columnar structure region and the second columnar structure region, being brought into contact with a vicinity of the tips of the pillar-shaped objects originating from the other columnar structure region.

3. The light diffusion film according to claim 1 , wherein a thickness of the overlapping columnar structure region is adjusted to a value within the range of 1 to 40 μm.

4. The light diffusion film according to claim 1 , wherein a thickness of the overlapping columnar structure region is adjusted to a value within the range of 0.1% to 10% relative to a film thickness, taken as 100%.

5. The light diffusion film according to claim 1 , wherein in the overlapping columnar structure region, the absolute value of the difference between angles of inclination of the pillar-shaped objects respectively originating from the first columnar structure region and the second columnar structure region is adjusted to a value of 1° or more.

6. The light diffusion film according to claim 1 , where in a main component of the pillar-shaped objects in the first columnar structure region and the second columnar structure region is a (meth)acrylic acid ester polymer containing plural aromatic rings, and a main component of the region having a relatively low refractive index is a polymer of urethane (meth)acrylate.

7. A light diffusion film comprising a single-layered light diffusion layer including, sequentially from the lower part of the film along a film thickness direction, a first columnar structure region and a second columnar structure region in which plural pillar-shaped objects having a relatively high refractive index are arranged to stand close together in a region having a relatively low refractive index,
the light diffusion film being a photocured product of a composition for a light diffusion film, and
wherein the light diffusion film comprises an overlapping columnar structure region in which an upper end of the first columnar structure region extends into a lower end of the second columnar structure region so that the upper end of the first columnar structure region and the lower end of the second columnar structure region overlap with each other in a cross section of the light diffusion film when the light diffusion film is cut at a plane that is perpendicular to a light diffusion film plane and cuts the pillar-shaped objects into two along axial lines in the second columnar structure region.

8. The light diffusion film according to claim 7 , wherein the overlapping columnar structure region is formed by tips of anyone side of the pillar-shaped objects respectively originating from the first columnar structure region and the second columnar structure region, being brought into contact with a vicinity of the tips of the pillar-shaped objects originating from the other columnar structure region.

9. The light diffusion film according to claim 7 , wherein a thickness of the overlapping columnar structure region is adjusted to a value within the range of 1 to 40 μm.

10. The light diffusion film according to claim 7 , wherein a thickness of the overlapping columnar structure region is adjusted to a value within the range of 0.1% to 10% relative to a film thickness, taken as 100%.

11. The light diffusion film according to claim 7 , wherein in the overlapping columnar structure region, the absolute value of the difference between angles of inclination of the pillar-shaped objects respectively originating from the first columnar structure region and the second columnar structure region is adjusted to a value of 1° or more.

12. The light diffusion film according to claim 7 , where in a main component of the pillar-shaped objects in the first columnar structure region and the second columnar structure region is a (meth)acrylic acid ester polymer containing plural aromatic rings, and a main component of the region having a relatively low refractive index is a polymer of urethane (meth)acrylate.

13. A method for manufacturing a light diffusion film, the method comprising the following steps (a) to (d):
(a) a step of preparing a composition for light diffusion film;
(b) a step of applying the composition for light diffusion film on a process sheet, and forming a coating layer;
(c) a step of subjecting the coating layer to first active energy ray irradiation, and forming a first columnar structure region in a lower portion of the coating layer, in which plural pillar-shaped objects having a relatively high refractive index are arranged to stand close together in a region having a relatively low refractive index, while leaving a columnar structure-unformed region in an upper portion of the coating layer and
(d) a step of subjecting the coating layer to second active energy ray irradiation, and forming a second columnar structure region in the columnar structure-unformed region, in which plural pillar-shaped objects having a relatively high refractive index are arranged to stand close together in a region having a relatively low refractive index, and wherein an upper end of the first columnar structure region extends into a lower end of the second columnar structure region so that the upper end of the first columnar structure region and the lower end of the second columnar structure region overlap with each other in a cross-section of the light diffusion film when the light diffusion film is cut at a plane that is perpendicular to a light diffusion film plane and cuts the pillar-shaped objects into two along axial lines in the first columnar structure region.

14. The method for manufacturing a light diffusion film according to claim 13 , wherein the first active energy ray irradiation is performed in an oxygen-containing atmosphere, while the second active energy ray irradiation is performed in a non-oxygen atmosphere.

15. A method for manufacturing a light diffusion film, the method comprising the following steps (a) to (d):
(a) a step of preparing a composition for light diffusion film;
(b) a step of applying the composition for light diffusion film on a process sheet, and forming a coating layer;
(c) a step of subjecting the coating layer to first active energy ray irradiation, and forming a first columnar structure region in a lower portion of the coating layer, in which plural pillar-shaped objects having a relatively high

Assignees

• Lintec Corp

Inventors

• Kusama Kentaro
• Katagiri Baku
• Orui Tomoo
• Shoshi Satoru

Classifications

• G02B5/0257

  creating an anisotropic diffusion characteristic, i.e. distributing output differently in two perpendicular axes · CPC title

• G02F1/133504

  Diffusing, scattering, diffracting elements (associated to illuminating devices G02F1/133606) · CPC title

• G02B5/0278

  used in transmission · CPC title

• G02B5/0247 Primary

  by means of voids or pores · CPC title

• G02B2207/123

  Optical louvre elements, e.g. for directional light blocking · CPC title