JP2014126771A - Method of manufacturing light diffusion film, and light diffusion film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a light diffusion film which is capable of diffusing incident light to form an elliptical shape on a plane parallel therewith and is highly suitable for use with rectangular displays, and to provide such light diffusion film.SOLUTION: A method of manufacturing a light diffusion film includes a step of irradiating a coating layer with active energy rays such that an azimuthal direction of a minimum incident angular width of the active energy rays is orthogonal to an azimuthal direction of a maximum incident angular width of the active energy rays at an arbitrary point in a region on a coating layer surface having the greatest illuminance of the active energy rays from an active energy ray source, where the minimum value of the incident angular width of the active energy rays shall be no more than 10°, and the maximum value of the incident angular width of the active energy rays shall be more than 10°and no more than 40°.

Description

The present invention relates to a method for producing a light diffusion film and a light diffusion film.
In particular, the present invention relates to a method of manufacturing a light diffusion film that can diffuse incident light in an elliptical shape with respect to a plane parallel to the light diffusion film, and is excellent in applicability to a rectangular display, and to such a light diffusion film. .

  Conventionally, for example, in the optical technical field to which a liquid crystal display device or the like belongs, a light diffusion film that diffuses incident light from a specific direction in a specific direction and allows incident light from other directions to pass straight through as it is Use is suggested.

  As such a light diffusion film, various modes are known. In particular, in the film, a plurality of plate-like regions having different refractive indexes are alternately arranged along any one direction along the film surface. A light diffusion film having a louver structure is widely known (for example, Patent Document 1).

  That is, in Patent Document 1, a resin composition composed of a plurality of compounds having one or more polymerizable carbon-carbon double bonds in a molecule having a difference in refractive index is maintained in a film shape and specified. A first step of curing the composition by irradiating ultraviolet rays from the direction of the step, and irradiating ultraviolet rays from a direction different from the first step while maintaining the resin composition on the obtained cured product as a film. The manufacturing method of the light control board (light diffusion film) characterized by comprising the 2nd process hardened in this and repeating a 2nd process as needed is disclosed.

  On the other hand, as another type of light diffusing film, there is a light diffusing film having a column structure in which a plurality of pillars having a relatively high refractive index are forested in a region having a relatively low refractive index. Widely known (for example, Patent Documents 2 to 3).

  That is, in Patent Document 2, a linear light source is disposed so as to face and separate from the photocurable resin composition film, and the linear light source is moved while moving at least one of the photocurable resin composition film and the linear light source. Is a manufacturing apparatus for forming a light control film (light diffusion film) by irradiating light from a photocurable resin composition film, wherein the axial direction and the moving direction of the linear light source intersect each other, A plurality of opposed thin plate-like light shielding members are provided between the photocurable resin composition film and the linear light source at a predetermined interval in a direction substantially perpendicular to the moving direction, and the light curable resin of the light shielding member. An apparatus for manufacturing a light control film (light diffusion film) is disclosed in which one side facing the composition film is provided in the same direction as the moving direction.

  Further, in Patent Document 3, a composition containing a photocurable compound is provided in a sheet shape, and the composition is cured by irradiating the sheet with a parallel light beam from a predetermined direction P, and parallel to the direction P inside the sheet. Is a method of manufacturing a light diffusion film that forms an aggregate of a plurality of rod-shaped cured regions extending in a line, and a set of cylindrical objects arranged in parallel to the direction P between a linear light source and a sheet. A method for producing a light diffusing film is disclosed, characterized in that light irradiation is performed through this cylindrical object.

JP 63-309902 A (Claims) JP 2009-173018 A (Claims) Japanese Patent Laying-Open No. 2005-292219 (Claims)

However, when the light diffusing film is manufactured using the manufacturing method of Patent Document 1, the component orthogonal to the direction of the louver structure extending in any one direction along the film surface among the components included in the incident light is sufficient. However, it was difficult to sufficiently diffuse the component parallel to the direction of the louver structure.
As a result, although the major axis in the shape of diffused light is sufficiently long, the minor axis is remarkably shortened, which makes it difficult to apply to a widely used rectangular display. It was.

  On the other hand, when the light diffusing film is manufactured using the manufacturing apparatus of Patent Document 2 and the manufacturing method of Patent Document 3, unlike the case of Patent Document 1, although incident light can be uniformly diffused, Since the shape becomes a circle, there is a problem that it is difficult to apply to a rectangular display in which required viewing angles are different in a horizontal direction and a vertical direction that are widely used.

Accordingly, the inventors of the present invention have made diligent efforts in view of the circumstances as described above, and when irradiating active energy rays to the coating layer, the incident angle width is within a predetermined range for each azimuth angle direction. It was found that a light diffusing film capable of diffusing incident light into an elliptical shape with respect to a plane parallel to the light diffusing film can be obtained by irradiating the active energy ray controlled to the value of Was completed.
That is, an object of the present invention is to allow incident light to be diffused in an elliptical shape with respect to a plane parallel to the light diffusing film, and a method for producing a light diffusing film excellent in applicability to a rectangular display and its It is in providing such a light-diffusion film.

According to this invention, the manufacturing method of the light-diffusion film characterized by including the following process (a)-(c) is provided, and the problem mentioned above can be solved.
(A) Step of preparing a composition for light diffusing film (b) Step of applying the composition for light diffusing film to a process sheet and forming a coating layer (c) Irradiating active energy rays to the coating layer An orientation in which the incident angle width of the active energy ray takes a minimum value at an arbitrary point located on the surface of the coating layer where the illuminance of the active energy ray from the active energy ray light source is maximum. The angle direction and the azimuth angle direction where the incident angle width of the active energy ray takes the maximum value are orthogonal to each other, and the minimum value of the incident angle width of the active energy ray is set to 10 ° or less, and The step of setting the maximum incident angle width of energy rays to a value in the range of more than 10 ° and not more than 40 ° That is, in the method for producing a light diffusing film of the present invention, active energy rays are applied to the coating layer. When irradiating the film, it is characterized by irradiating an active energy ray whose incident angle width is controlled to a value within a predetermined range for each azimuth direction. A predetermined internal structure different from the column structure can be formed.
As a result, incident light can be diffused in an elliptical shape with respect to a plane parallel to the light diffusing film, and a light diffusing film excellent in applicability to a rectangular display can be efficiently manufactured.

In carrying out the method for producing a light diffusing film of the present invention, in step (c), a linear light source as an active energy ray light source and an incident angle width of the active energy ray from the linear light source are adjusted. The incident angle width adjusting member is preferably used, and the incident angle width adjusting member is preferably disposed between the linear light source and the coating layer and in the active energy ray emission region from the linear light source.
By carrying out in this way, the active energy ray from the linear light source is converted into an active energy ray whose incident angle width is controlled to a value within a predetermined range for each azimuth angle direction, and applied to the coating layer. Can be irradiated.

Moreover, when implementing the manufacturing method of the light-diffusion film of this invention, while an incident angle width adjustment member consists of a some plate-shaped member, a some plate-like member is arrange | positioned in parallel, making each main surface oppose. In addition, it is preferable that the main surface described above is parallel to the vertical direction.
By carrying out in this way, the active energy ray from the linear light source can be effectively converted into an active energy ray whose incident angle width is controlled to a value within a predetermined range for each azimuth angle direction.

Moreover, when implementing the manufacturing method of the light-diffusion film of this invention, it is preferable to make the space | interval between several plate-shaped members into the value within the range of 1-1000 mm.
By carrying out in this way, the active energy ray from the linear light source can be more effectively converted into an active energy ray whose incident angle width is controlled to a value within a predetermined range for each azimuth angle direction. .

Moreover, when implementing the manufacturing method of the light-diffusion film of this invention, it is preferable to make the length of the up-down direction in a plate-shaped member into the value within the range of 10-1000 mm.
By carrying out in this way, the active energy ray from the linear light source can be more effectively converted into an active energy ray whose incident angle width is controlled to a value within a predetermined range for each azimuth angle direction. .

Moreover, when implementing the manufacturing method of the light-diffusion film of this invention, it is preferable to make the thickness of a plate-shaped member into the value within the range of 0.1-5 mm.
By implementing in this way, the distortion of the plate-shaped member resulting from an active energy ray can be effectively suppressed, suppressing the influence of the shadow by an incident angle width adjusting member.

In carrying out the method for producing a light diffusing film of the present invention, the distance between the lower end of the incident angle width adjusting member and the surface of the coating layer may be set to a value within the range of 0.1 to 1000 mm. preferable.
By carrying out in this way, the active energy ray from the linear light source is more effectively set to a predetermined incident angle width for each azimuth direction while more effectively suppressing the influence of the shadow by the incident angle width adjusting member. It can be converted into an active energy ray controlled to a value within the range of.

In carrying out the method for producing a light diffusing film of the present invention, the distance between the upper end of the incident angle width adjusting member and the lower end of the linear light source is preferably set to a value within the range of 0.1 to 1000 mm. .
By configuring in this way, the active energy line from the linear light source is more effectively converted into an active energy line whose incident angle width is controlled to a value within a predetermined range for each azimuth angle direction, while applying A sufficient amount of active energy rays can be irradiated to the layer.

Another aspect of the present invention is a light diffusing film characterized in that incident light is diffused in an elliptical shape with respect to a plane parallel to the light diffusing film.
That is, the light diffusion film of the present invention has a predetermined internal structure that is different from the conventional louver structure and different from the conventional column structure in the film, so that incident light is directed to a plane parallel to the light diffusion film. The light can be diffused into an elliptical shape and can be easily applied to a rectangular display.

Further, in constituting the light diffusion film of the present invention, the opening angle of the diffused light in the major axis direction in the elliptical light diffusion is θ2 (°), and the opening angle of the diffused light in the minor axis direction is θ2 ′ (°). In this case, it is preferable that the following relational expression (1) is satisfied.
0.2 ≦ θ2 ′ / θ2 ≦ 0.9 (1)
By comprising in this way, the applicability with respect to a rectangular display can further be improved.

Moreover, when comprising the light-diffusion film of this invention, it is preferable to be obtained by the manufacturing method containing following process (a)-(c).
(A) Step of preparing a composition for light diffusing film (b) Step of applying the composition for light diffusing film to a process sheet and forming a coating layer (c) Irradiating active energy rays to the coating layer An orientation in which the incident angle width of the active energy ray takes a minimum value at an arbitrary point located on the surface of the coating layer where the illuminance of the active energy ray from the active energy ray light source is maximum. The angle direction and the azimuth angle direction where the incident angle width of the active energy ray takes the maximum value are orthogonal to each other, and the minimum value of the incident angle width of the active energy ray is set to 10 ° or less, and The process of setting the maximum incident angle width of the energy beam to a value in the range of more than 10 ° and not more than 40 ° By configuring in this way, unlike the conventional louver structure in the film, A predetermined internal structure different from the ram structure can be more efficiently formed, and the applicability to a rectangular display can be further improved.

Fig.1 (a)-(b) is a figure provided in order to demonstrate the outline of the light-diffusion film which has a louver structure in a film. FIGS. 2A to 2B are diagrams for explaining incident angle dependency and anisotropic light diffusion in a light diffusion film having a louver structure in the film. FIGS. 3A to 3B are views for explaining an outline of a light diffusion film having a column structure in the film. 4 (a) to 4 (b) are diagrams for explaining the incident angle dependency and the isotropic light diffusion in the light diffusion film having a column structure in the film. FIGS. 5A to 5C are diagrams and photographs provided for explaining the outline of the light diffusion film obtained by the production method of the present invention. 6 (a) to 6 (b) are other diagrams and photographs provided for explaining the outline of the light diffusion film obtained by the production method of the present invention. FIGS. 7A to 7C are diagrams for explaining the incident angle dependency and the elliptical light diffusion in the light diffusion film obtained by the production method of the present invention. FIGS. 8A to 8C are diagrams provided to explain the outline of the production method of the present invention. FIGS. 9A to 9C are diagrams for explaining the control of the incident angle width for each azimuth angle direction. FIG. 10 is a diagram for explaining the relationship between the maximum value of the incident angle width and the elliptical light diffusion. FIGS. 11A to 11B are diagrams provided for explaining the arrangement of the incident angle width adjusting member. 12 (a) to 12 (b) are diagrams for explaining the active energy ray irradiation process. FIGS. 13A to 13C are photographs provided to explain the state of a plurality of cross sections having different ways of cutting in the light diffusion film of Example 1. FIG. 14A to 14B are light reception angle-relative luminance charts for explaining light diffusion characteristics in the light diffusion film of Example 1. FIG. FIGS. 15A to 15B are a photograph and a diagram for explaining the light diffusion characteristics in the light diffusion film of Example 1. FIG. 16 (a) to 16 (c) are diagrams provided to explain the state of a plurality of cross sections in which the light diffusing film of Comparative Example 1 is cut differently. 17A to 17B are light reception angle-relative luminance charts for explaining light diffusion characteristics in the light diffusion film of Comparative Example 1. FIG. 18A to 18B are a photograph and a diagram for explaining the light diffusion characteristics of the light diffusion film of Comparative Example 1. FIG. 19 (a) to 19 (c) are diagrams provided for explaining the state of a plurality of cross sections in which the light diffusing film of Comparative Example 2 is cut differently. 20A to 20B are light reception angle-relative luminance charts for explaining the light diffusion characteristics in the light diffusion film of Comparative Example 2. FIG. 21A to 21B are a photograph and a diagram for explaining the light diffusion characteristics in the light diffusion film of Comparative Example 2. FIG.

Embodiment of this invention is a manufacturing method of the light-diffusion film characterized by including the following process (a)-(c).
(A) Step of preparing a composition for light diffusing film (b) Step of applying the composition for light diffusing film to a process sheet and forming a coating layer (c) Irradiating active energy rays to the coating layer An orientation in which the incident angle width of the active energy ray takes a minimum value at an arbitrary point located on the surface of the coating layer where the illuminance of the active energy ray from the active energy ray light source is maximum. The angle direction and the azimuth angle direction where the incident angle width of the active energy ray takes the maximum value are orthogonal to each other, and the minimum value of the incident angle width of the active energy ray is set to 10 ° or less, and Step of setting the maximum value of the incident angle width of the energy beam to a value in the range of more than 10 ° and not more than 40 ° Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings as appropriate. Easy to understand First, the basic principle of light diffusion in the light diffusion film will be described.

1. Basic Principle of Light Diffusion in Light Diffusion Film (1) Anisotropic Light Diffusion First, a light diffusion film having anisotropic light diffusion characteristics will be described with reference to FIGS.
First, FIG. 1A shows a top view (plan view) of the anisotropic light diffusing film 10, and FIG. 1B shows the anisotropic light diffusing film 10 shown in FIG. A cross-sectional view of the anisotropic light diffusion film 10 when cut in the vertical direction along A-A and viewing the cut surface in the arrow direction is shown.
2A shows an overall view of the anisotropic light diffusion film 10 having a louver structure in the film, and FIG. 2B shows the anisotropic light diffusion film 10 of FIG. 2A in the X direction. Sectional drawing at the time of seeing from is shown.
As shown in the plan view of FIG. 1A, the anisotropic light diffusion film 10 has a relatively high refractive index and a relatively high refractive index in a given direction along the film surface. Is provided with a louver structure 13 in which plate-like regions 14 having a low height are alternately arranged in parallel.
As shown in the cross-sectional view of FIG. 1B, the plate-like region 12 having a relatively high refractive index and the plate-like region 14 having a relatively low refractive index each have a predetermined thickness. In the normal direction (film thickness direction) with respect to the anisotropic light diffusing film 10, the state of being alternately arranged in parallel is maintained.

Thereby, as shown to Fig.2 (a), when the incident angle of incident light is in a light-diffusion incident angle area | region, it is estimated that it diffuses with the anisotropic light-diffusion film 10. FIG.
That is, as shown in FIG. 1B, the incident angle of incident light on the anisotropic light diffusing film 10 is a value within a predetermined angle range from parallel to the boundary surface 13 ′ of the louver structure 13, that is, light diffusing incident. When the value is in the angle region, the incident light (52, 54) passes along the film thickness direction while changing the direction inside the plate-like region 12 having a relatively high refractive index in the louver structure. By passing through, it is presumed that the traveling direction of light on the light exit surface side is not uniform.
As a result, when the incident light is within the light diffusion incident angle region, it is estimated that the incident light is diffused by the anisotropic light diffusion film 10 and becomes diffused light (52 ′, 54 ′).
On the other hand, when the incident angle of the incident light with respect to the anisotropic light diffusion film 10 deviates from the light diffusion incident angle region, the incident light 56 is diffused by the anisotropic light diffusion film as shown in FIG. However, it is presumed that the light passes through the anisotropic light diffusion film 10 as it is and becomes the transmitted light 56 '.
In the present invention, the “light diffusion incident angle region” refers to the angle of incident light corresponding to emitting diffused light when the angle of incident light from a point light source is changed with respect to the light diffusing film. Means range.
In addition, such “light diffusion incident angle region” is caused by a difference in refractive index such as a louver structure or a tilt angle in a light diffusion film, as shown in FIGS. 2 (a), 4 (a) and 7 (a). The angle region determined for each light diffusion film.

Based on the above basic principle, the anisotropic light diffusion film 10 provided with the louver structure 13 can exhibit incident angle dependency in light transmission and diffusion as shown in FIG. 2A, for example.
As shown in FIG. 2A, the anisotropic light diffusion film 10 having the louver structure 13 usually has “anisotropy” as its light diffusion characteristics.
Here, in the present invention, “anisotropy” means, as shown in FIG. 2 (a), when incident light is diffused by the film, in the plane parallel to the film in the diffused emitted light, The light diffusion state (diffused light spreading shape) means a property that varies depending on the direction in the same plane.
More specifically, as shown in FIG. 2A, light is selectively diffused in the direction perpendicular to the louver structure extending along any one direction along the film surface, while the louver structure It is estimated that anisotropic light diffusion is realized because light diffusion hardly occurs in the direction parallel to.
Therefore, the spreading shape of the diffused light in the anisotropic light diffusing film is a rod shape as shown in FIG.

Further, as described above, in the anisotropic light diffusing film, light diffusion occurs in a direction perpendicular to the louver structure extending along any one direction along the film surface, and as shown in FIG. In addition, the “incident angle θ1” of incident light means an incident angle of a component perpendicular to the direction of the louver structure extending along one arbitrary direction along the film surface. Further, at this time, the incident angle θ1 means an angle (°) when the angle with respect to the normal to the incident side surface of the light diffusion film is 0 °.
In the present invention, the “light diffusion angle region” means an angle range of diffused light obtained by fixing a point light source at an angle at which incident light is most diffused with respect to the light diffusion film. Shall.
Furthermore, in the anisotropic light diffusion film, the “diffuse light opening angle” is the width of the “light diffusion angle region” described above, and as shown in FIG. The opening angle θ2 of the diffused light when the cross section of the film is viewed from the direction parallel to the direction of the louver structure extending along the X direction (X direction).

In addition, as shown in FIG. 2A, the anisotropic light diffusion film has a light exit surface side when the incident angle of incident light is included in the light diffusion incident angle region even if the incident angle is different. In FIG. 5, substantially the same light diffusion can be performed.
Therefore, it can be said that the obtained anisotropic light-diffusion film has a condensing effect | action which concentrates light on a predetermined location.
In addition, the direction change of the incident light inside the region 12 having a relatively high refractive index in the louver structure is a step index type in which the direction changes linearly and zigzag by total reflection as shown in FIG. In addition to the case, a gradient index type in which the direction changes in a curved shape may be considered.
1A and 1B, the interface between the plate-like region 12 having a relatively high refractive index and the plate-like region 14 having a relatively low refractive index is represented by a straight line for the sake of simplicity. In practice, however, the interface is slightly meandering, and each plate-like region forms a complex refractive index distribution structure with branching and extinction.
As a result, it is estimated that the non-uniform distribution of optical characteristics enhances the light diffusion characteristics.

(2) Isotropic light diffusion Next, a light diffusion film having isotropic light diffusion characteristics will be described with reference to FIGS.
First, FIG. 3A shows a top view (plan view) of the isotropic light diffusion film 20, and FIG. 3B shows the isotropic light diffusion film 20 shown in FIG. A cross-sectional view of the isotropic light diffusion film 20 when cut in the vertical direction along A-A and viewing the cut surface in the arrow direction is shown.
4A shows an overall view of the isotropic light diffusion film 20 having a column structure in the film, and FIG. 4B shows the isotropic light diffusion film 20 of FIG. 4A in the X direction. Sectional drawing at the time of seeing from is shown.
As shown in the plan view of FIG. 3A, the isotropic light diffusion film 20 has a column structure 23 including a columnar body 22 having a relatively high refractive index and a region 24 having a relatively low refractive index. doing.
Further, as shown in the cross-sectional view of FIG. 3B, the columnar object 22 having a relatively high refractive index and the region 24 having a relatively low refractive index are in the normal direction (film thickness) with respect to the isotropic light diffusion film 20. In the direction), each of which has a predetermined width and is alternately arranged.

Thereby, as shown to Fig.4 (a), when the incident angle of incident light is in a light-diffusion incident angle area | region, it is estimated that it is diffused by the isotropic light-diffusion film 20. FIG.
That is, as shown in FIG. 3B, the incident angle of the incident light with respect to the isotropic light diffusion film 20 is a value in a predetermined angle range with respect to the boundary surface 23 ′ of the column structure 23, that is, a light diffusion incident angle region. The incident light (62, 64) passes through the columnar object 22 having a relatively high refractive index in the column structure along the film thickness direction while changing the direction. It is estimated that the traveling direction of light on the light exit surface side is not uniform.
As a result, when the incident light is within the light diffusion incident angle region, it is estimated that the incident light is diffused by the isotropic light diffusion film 20 and becomes diffused light (62 ′, 64 ′).
On the other hand, when the incident angle of the incident light with respect to the isotropic light diffusion film 20 deviates from the light diffusion incident angle region, the incident light 66 is diffused by the isotropic light diffusion film as shown in FIG. However, it is presumed that the light is transmitted through the isotropic light diffusion film 20 as it is and becomes transmitted light 66 '.

Therefore, the isotropic light diffusing film 20 having the column structure 23 is based on the same basic principle as the anisotropic light diffusing film described above. For example, as shown in FIG. Can be achieved.
However, as shown in FIG. 4A, the isotropic light diffusion film having the column structure 23 usually has “isotropic” as its light diffusion characteristics.
This is presumably due to light passing through the column structure 23 while repeating step index type or gradient index type reflection in the column structure even in a cross section perpendicular to the cross section shown in FIG. .
Here, in the present invention, “isotropic” means that, as shown in FIG. 4A, when incident light is diffused by a film, the diffused emitted light is in a plane parallel to the film, This means that the light diffusion state (the shape of the spread of the diffused light) does not change depending on the direction in the same plane.
More specifically, as shown in FIG. 4A, the diffusion degree of the diffused outgoing light is circular in a plane parallel to the film.

In the isotropic light diffusion film, the direction in which light diffusion occurs is not particularly limited, unlike the anisotropic light diffusion film.
Therefore, when the “incident angle θ1” of incident light in the isotropic light diffusion film is referred to, it simply means an angle (°) when the angle with respect to the normal to the incident side surface of the isotropic light diffusion film is 0 °. And
About other contents, since it overlaps with the contents of the anisotropic light diffusion film mentioned above, it abbreviate | omits.

(3) Elliptical Light Diffusion Next, a light diffusing film having an elliptical light diffusing characteristic, that is, a light diffusing film obtained by the production method of the present invention will be described with reference to FIGS.
First, FIG. 5A shows an estimated structure of a top view (plan view) of the elliptical light diffusion film 30, and FIG. 5B shows the elliptical light diffusion film 30 with a dotted line A−. A cross-sectional photograph of the elliptical light diffusion film 30 when cut in the vertical direction along A and the cut surface is photographed in the arrow direction is shown.
FIG. 5C shows a cross section of the elliptical light diffusion film 30 when the elliptical light diffusion film 30 is cut in the vertical direction along the dotted line BB and the cut surface is photographed in the direction of the arrow. The picture is shown.
FIG. 6A shows a state in which the elliptical light diffusion film 30 is cut by a plane C having an inclination of 45 degrees with respect to the film surface. FIG. 6B shows an elliptical shape. A cross-sectional photograph of the elliptical light diffusing film 30 is shown in which the cut surface of the light diffusing film 30 cut along the plane C is photographed from the front, that is, in the direction of the arrow D.
Further, FIG. 7A shows an overall image of the elliptical light diffusion film 30, and FIG. 7B shows the elliptical light diffusion film 30 of FIG. 7A viewed from the X direction. A cross-sectional view is shown, and FIG. 7C shows a cross-sectional view of the elliptical light diffusion film 30 of FIG. 7A viewed from the Y direction.

As shown in the plan view of FIG. 5A, the elliptical light diffusion film 30 includes a plurality of lamellar objects 32 arranged in any one direction along the film surface, and the lamellar objects 32. Is presumed to have a predetermined internal structure 33 composed of different refractive index regions 34 having different refractive indexes.
That is, unlike the conventional louver structure extending over the entire surface of the film, either the plate-like region having a relatively high refractive index or the plate-like region having a relatively low refractive index in the louver structure is cut off, and the end portion is cut. It is presumed that the formed short plate-shaped region, that is, the flaky material 32 is included.
Hereinafter, the predetermined internal structure 33 will be described in detail.

That is, as shown in the cross-sectional photograph of FIG. 5B, when the elliptical light diffusion film 30 is cut along the dotted line AA, the flaky object 32 and the different refractive index region 34 are elliptical. Along the dotted line AA of the light diffusion film 30, the state of being alternately arranged is maintained.
Therefore, it is the same as the louver structure that the predetermined internal structure 33 is a structure in which the flakes 32 and the different refractive index regions 34 are alternately arranged.
On the other hand, as shown in the cross-sectional photograph of FIG. 5C, when the elliptical light diffusion film 30 is cut along a dotted line BB orthogonal to the dotted line AA, the predetermined internal structure 33 is a louver. It has an intermediate structure between the structure and the column structure.
That is, it has been confirmed by observation that the predetermined internal structure 33 is a refractive index distribution structure that is denser than the louver structure and sparser than the column structure.
This is shown more clearly in the photograph of the 45 ° oblique cut surface shown in FIG. 6 (b).
That is, from FIG. 6 (b), different from the louver structure and the column structure, a plurality of flaky objects arranged in one arbitrary direction along the film surface and the flaky objects have different refractive indexes. It can be seen that a predetermined internal structure composed of the refractive index region is formed.

In addition, unlike the louver structure and the column structure described above, the predetermined internal structure 33 in the elliptical light diffusing film 30 is presumed to change in the film thickness direction.
That is, as shown in the cross-sectional photograph of FIG. 6 (b), on the surface side of the elliptical light diffusing film 30, the length in the arrangement direction of the plurality of flakes 32 is relatively short and the width is also thin. Has been observed.
On the other hand, on the bottom surface side of the elliptical light diffusing film 30, it has been observed that the length of the plurality of lamellar objects 32 in the arrangement direction is relatively long and the width is also thick.
Therefore, at the present stage, the predetermined internal structure 33 in the elliptical light diffusing film 30 cannot be accurately specified. However, as the film faces from the surface side to the bottom surface side, the plurality of lamellar objects 32 are respectively It is presumed to be a continuous structure that is gradually integrated and integrated.

In any case, an elliptical light diffusing film 30 having a predetermined internal structure 33 according to the same basic principle as the anisotropic light diffusing film and the isotropic light diffusing film described above is, for example, as shown in FIG. It is possible to exhibit the incident angle dependency in the transmission and diffusion of light.
However, as shown in FIGS. 7A to 7C, the elliptical light diffusing film 30 has a predetermined internal structure 33 different from the louver structure and the column structure. It is estimated that it will have the following light diffusion characteristics.
More specifically, in the flaky material constituting the predetermined internal structure, it is presumed that the central plate-like portion expresses anisotropic light diffusion and the end portion expresses isotropic light diffusion.
For this reason, it is estimated that elliptical light diffusion occurs in a predetermined internal structure.
That is, in the louver structure, since the plate-like region constituting the louver basically has no end portion, light diffusion with strong anisotropy and little isotropic property, that is, anisotropic light diffusion occurs.
Further, in the column structure, since the columnar material constituting the column structure does not have a plate-like portion, light diffusion having strong isotropic property and almost no anisotropy, that is, isotropic light diffusion occurs.
Therefore, in the predetermined internal structure provided with the flakes having both the plate-like portion and the end, light diffusion occurs between the louver structure and the column structure, and an elliptical shape having both anisotropy and isotropic properties. It is estimated that light diffusion occurs.

Further, in the elliptical light diffusion film, as shown in FIG. 7B, the major axis direction in the elliptical light diffusion is in the arrangement direction of the flakes formed in any one direction along the film surface. Because of the vertical orientation, the “incident angle θ1” of the incident light means the incident angle of the component perpendicular to the arrangement direction of the flakes arranged in any one direction along the film surface. It shall be. Further, at this time, the incident angle θ1 means an angle (°) when the angle with respect to the normal to the incident side surface of the light diffusion film is 0 °.
In addition, in the elliptical light diffusion film, the “diffuse light opening angle” is, as shown in FIG. 7 (b), an arrangement direction of flaky products arranged in an arbitrary direction along the film surface. When the cross section of the film is viewed from the parallel X direction, when the cross section of the film is viewed from the Y direction perpendicular to the X direction, as shown in FIG. And the spread angle θ2 ′ of the diffused light in the minor axis direction is defined.
About other contents, since it overlaps with the contents of the anisotropic light diffusion film mentioned above, it abbreviate | omits.

2. Step (a): Step of Preparing a Composition for Light Diffusion Film This step is a step of preparing a predetermined composition for light diffusion film.
More specifically, it is a step of mixing at least two polymerizable compounds having different refractive indexes, a photopolymerization initiator, and other additives as required.
In mixing, the mixture may be stirred as it is at room temperature. However, from the viewpoint of improving uniformity, for example, stirring is performed under a heating condition of 40 to 80 ° C. to obtain a uniform mixed solution. Is preferred.
Moreover, it is also preferable to add a dilution solvent so that it may become the desired viscosity suitable for coating.
Hereinafter, the composition for light diffusion films will be described more specifically.
At the present stage, of the flaky material and the different refractive index region constituting the predetermined internal structure, which is derived from the high refractive index polymerizable compound and which is derived from the low refractive index polymerizable compound There is no clear conclusion.
However, in the conventional column structure, considering that it has been confirmed that the columnar material is derived from the high refractive index polymerizable compound and the low refractive index region is derived from the low refractive index polymerizable compound, the flaky shape There is a high possibility that the product is derived from a polymerizable compound having a high refractive index and the different refractive index region is derived from a polymerizable compound having a low refractive index.
Therefore, in the following, for the sake of convenience, the explanation will be made on the assumption that the flaky material is derived from a polymerizable compound having a high refractive index and the different refractive index region is derived from a polymerizable compound having a low refractive index.
However, even if such an assumption is contrary to the fact, it is merely an assumption for convenience of explanation, and thus the technical idea of the present invention itself is not denied.

(1) High Refractive Index Polymerizable Compound (1) -1 Type Among two polymerizable compounds having different refractive indices, a polymerizable compound having a relatively high refractive index (hereinafter sometimes referred to as component (A)). Type) is not particularly limited, but the main component is preferably a (meth) acrylic acid ester containing a plurality of aromatic rings.
The reason for this is that by including a specific (meth) acrylic acid ester as the component (A), the polymerization rate of the component (A) is changed to a polymerizable compound having a relatively low refractive index (hereinafter referred to as (B). It is presumed that the polymerization rate between these components can be effectively reduced by making the polymerization rate faster than the polymerization rate of the component)) It is to be done.
As a result, when photocured, a plurality of flakes having a relatively high refractive index derived from the component (A) in a different refractive index region having a relatively low refractive index derived from the component (B) It is possible to efficiently form a predetermined internal structure in which the are arranged.
In addition, by including a specific (meth) acrylic acid ester as the component (A), the monomer stage has sufficient compatibility with the component (B), but a plurality of stages in the polymerization process. Then, it is presumed that the compatibility with the component (B) can be reduced to a predetermined range, and the predetermined internal structure can be formed more efficiently.
Furthermore, by including a specific (meth) acrylic acid ester as the component (A), the refractive index of the region derived from the component (A) in the predetermined internal structure is increased, and the region derived from the component (B) The difference from the refractive index can be adjusted to a predetermined value or more.
Therefore, by including a specific (meth) acrylic acid ester as the component (A), the refractive index is relatively low in the refractive index region having a relatively low refractive index, coupled with the characteristics of the component (B) described later. Therefore, it is possible to efficiently form a predetermined internal structure in which a plurality of relatively high flaky objects are arranged.
In addition, "(meth) acrylic acid ester containing a plurality of aromatic rings" means a compound having a plurality of aromatic rings in the ester residue portion of (meth) acrylic acid ester.
“(Meth) acrylic acid” means both acrylic acid and methacrylic acid.

  Examples of the (meth) acrylic acid ester containing a plurality of aromatic rings as the component (A) include, for example, biphenyl (meth) acrylate, naphthyl (meth) acrylate, anthracyl (meth) acrylate, Benzylphenyl (meth) acrylate, biphenyloxyalkyl (meth) acrylate, naphthyloxyalkyl (meth) acrylate, anthracyloxyalkyl (meth) acrylate, benzylphenyloxyalkyl (meth) acrylate, or aromatic Examples thereof include those in which a part of hydrogen atoms on the ring are substituted by halogen, alkyl, alkoxy, halogenated alkyl or the like.

  Moreover, it is preferable that the (meth) acrylic acid ester containing a plurality of aromatic rings as the component (A) includes a compound containing a biphenyl ring, and particularly includes a biphenyl compound represented by the following general formula (1). It is preferable.

(In General Formula (1), R ^{1 to} R ¹⁰ are each independent, and at least one of R ^{1 to} R ¹⁰ is a substituent represented by the following General Formula (2), and the rest is hydrogen. It is a substituent of any one of an atom, a hydroxyl group, a carboxyl group, an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, a carboxyalkyl group and a halogen atom.)

(In General Formula (2), R ¹¹ is a hydrogen atom or a methyl group, carbon number n is an integer of 1 to 4, and repetition number m is an integer of 1 to 10.)

The reason for this is that by including a biphenyl compound having a specific structure as the component (A), a predetermined difference is caused in the polymerization rate of the component (A) and the component (B), and the component (A) and the component (B) This is because it is estimated that the compatibility between the two components can be reduced by reducing the compatibility with the component to a predetermined range.
Moreover, the refractive index of the area | region derived from (A) component can be made high, and the difference with the refractive index of the area | region derived from (B) component can be adjusted more easily to a value more than predetermined.

Moreover, when R < ¹ > -R < ¹⁰ > in General formula (1) contains either an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, and a carboxyalkyl group, carbon number of the alkyl part is set. A value in the range of 1 to 4 is preferable.
This is because when the number of carbon atoms exceeds 4, the polymerization rate of the component (A) decreases or the refractive index of the region derived from the component (A) becomes too low, resulting in a predetermined internal This is because it may be difficult to efficiently form the structure.
Therefore, when R ^{1 to} R ¹⁰ in the general formula (1) include any of an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, and a carboxyalkyl group, the number of carbon atoms in the alkyl portion is determined. A value in the range of 1 to 3 is more preferable, and a value in the range of 1 to 2 is more preferable.

Moreover, it is preferable that R < ¹ > -R < ¹⁰ > in General formula (1) is a substituent other than a halogenated alkyl group or a halogen atom, ie, a halogen-free substituent.
This is because, when the light diffusion film is discarded, generation of dioxins due to incineration is prevented, which is preferable from the viewpoint of environmental protection.
In the conventional light diffusing film, in order to obtain a desired internal structure, halogen substitution is generally performed on the monomer component for the purpose of increasing the refractive index of the monomer component.
In this regard, the biphenyl compound represented by the general formula (1) can have a high refractive index even when halogen substitution is not performed.
Therefore, if it is a light-diffusion film formed by photocuring the composition for light-diffusion films in this invention, even if it does not contain a halogen, favorable incident angle dependence can be exhibited.
“Good incident angle dependency” means that the distinction between the light diffusion incident angle region and the non-diffuse incident angle region where the incident light is transmitted without being diffused is clearly controlled. .

Moreover, it is preferable that any one of R < ² > -R < ⁹ > in General formula (1) is a substituent represented by General formula (2).
This is because, by setting the position of the substituent represented by the general formula (2) to a position other than R ¹ and R ¹⁰ , the components (A) are oriented and crystallized in the stage before photocuring This is because it can be effectively prevented.
Furthermore, it is liquid at the monomer stage before photocuring, and apparently can be uniformly mixed with the component (B) without using a diluting solvent or the like.
Thereby, in the stage of photocuring, it is possible to agglomerate and phase separate the component (A) and the component (B) at a fine level, and more efficiently obtain a light diffusion film having a predetermined internal structure. It is because it can do.
Further, from the same viewpoint, it is particularly preferable that any one of R ³ , R ⁵ , R ⁶ and R ^{8 in} the general formula (1) is a substituent represented by the general formula (2).

Moreover, it is preferable to make the repeating number m in the substituent represented by General formula (2) into the integer of 1-10 normally.
The reason for this is that when the number of repetitions m exceeds 10, the oxyalkylene chain connecting the polymerization site and the biphenyl ring becomes too long, which may inhibit the polymerization of the components (A) at the polymerization site. Because.
Therefore, the repeating number m in the substituent represented by the general formula (2) is more preferably an integer of 1 to 4, and particularly preferably an integer of 1 to 2.
From the same viewpoint, it is preferable that the carbon number n in the substituent represented by the general formula (2) is usually an integer of 1 to 4.
In addition, considering the position of the polymerizable carbon-carbon double bond that is the polymerization site is too close to the biphenyl ring, the biphenyl ring becomes sterically hindered, and the polymerization rate of the component (A) decreases, The carbon number n in the substituent represented by the general formula (2) is more preferably an integer of 2 to 4, and particularly preferably an integer of 2 to 3.

  In addition, specific examples of the biphenyl compound represented by the general formula (1) include compounds represented by the following formulas (3) to (4).

(1) -2 Molecular weight Moreover, it is preferable to make the molecular weight of (A) component into the value within the range of 200-2,500.
The reason for this is that by setting the molecular weight of component (A) within a predetermined range, the polymerization rate of component (A) can be further increased, and the copolymerizability of component (A) and component (B) can be made more effective. This is because it is estimated that it can be lowered.
As a result, when photocured, a plurality of flakes having a relatively high refractive index derived from the component (A) in a different refractive index region having a relatively low refractive index derived from the component (B) It is possible to more efficiently form a predetermined internal structure in which the are arranged.
That is, when the molecular weight of the component (A) is less than 200, the polymerization rate decreases due to steric hindrance, becomes close to the polymerization rate of the component (B), and copolymerization with the component (B) is likely to occur. Because there is. On the other hand, when the molecular weight of the component (A) exceeds 2,500, the polymerization rate of the component (A) decreases as the difference in molecular weight with the component (B) decreases. This is because the polymerization rate of the component is close and it is estimated that copolymerization with the component (B) is likely to occur, and as a result, it may be difficult to efficiently form a predetermined internal structure.
Therefore, the molecular weight of the component (A) is more preferably set to a value within the range of 240 to 1,500, and further preferably set to a value within the range of 260 to 1,000.
The molecular weight of component (A) can be determined from the calculated value obtained from the molecular composition and the atomic weight of the constituent atoms, and can also be measured as a weight average molecular weight using gel permeation chromatography (GPC). .

(1) -3 Single use Moreover, the composition for light diffusion films in this invention is characterized by including (A) component as a monomer component which forms the area | region where the refractive index in a predetermined | prescribed internal structure is relatively high, However, the component (A) is preferably contained as one component.
The reason for this is that, by configuring in this way, it is possible to effectively suppress variations in the refractive index in the region derived from the component (A), that is, in a flaky material having a relatively high refractive index, and to achieve a predetermined internal structure. This is because the provided light diffusing film can be obtained more efficiently.
That is, when the compatibility with the component (B) in the component (A) is low, for example, when the component (A) is a halogen compound, the third component for compatibilizing the component (A) with the component (B) In other cases, other components (A) (for example, non-halogen compounds) are used in combination.
However, in this case, due to the influence of the third component, the refractive index in a region where the refractive index derived from the component (A) is relatively high may vary or be easily lowered.
As a result, the refractive index difference from the region having a relatively low refractive index derived from the component (B) may become non-uniform or may be excessively lowered.
Therefore, it is preferable to select a monomer component having a high refractive index that is compatible with the component (B) and use it as the sole component (A).
For example, since the biphenyl compound represented by the formula (3) as the component (A) has a low viscosity, it has compatibility with the component (B), so it is used as a single component (A). can do.

(1) -4 Refractive index Moreover, it is preferable to make the refractive index of (A) component into the value within the range of 1.5-1.65.
This is because the difference between the refractive index of the region derived from the component (A) and the refractive index of the region derived from the component (B) is obtained by setting the refractive index of the component (A) within the range. This is because the light diffusing film having a predetermined internal structure can be adjusted more easily and more efficiently.
That is, when the refractive index of the component (A) is less than 1.5, the difference from the refractive index of the component (B) becomes too small, and it may be difficult to obtain an effective light diffusion angle region. Because there is. On the other hand, when the refractive index of the component (A) exceeds 1.65, the difference with the refractive index of the component (B) increases, but even an apparent compatibility state with the component (B) is formed. This is because it may be difficult.
Therefore, the refractive index of the component (A) is more preferably set to a value within the range of 1.52 to 1.62, and further preferably set to a value within the range of 1.56 to 1.6.
In addition, the refractive index of (A) component mentioned above means the refractive index of (A) component before hardening by light irradiation.
The refractive index can be measured according to, for example, JIS K0062.

(1) -5 Content Further, the content of the component (A) in the composition for light diffusion film is 100 parts by weight of the component (B) which is a polymerizable compound having a relatively low refractive index, which will be described later. A value within the range of 25 to 400 parts by weight is preferred.
The reason for this is that when the content of the component (A) is less than 25 parts by weight, the ratio of the component (A) to the component (B) decreases and the width of the flakes derived from the component (A) This is because it may become difficult to obtain an internal structure having a good incident angle dependency. Moreover, it is because the length of the thin piece in the thickness direction of a light-diffusion film becomes inadequate, and may not show light diffusibility. On the other hand, when the content of the component (A) exceeds 400 parts by weight, the ratio of the component (A) to the component (B) increases, and the width of the flakes derived from the component (A) This is because it may become excessively large and, on the contrary, it may be difficult to obtain a predetermined internal structure having good incident angle dependency. Moreover, it is because the length of the thin piece in the thickness direction of a light-diffusion film becomes inadequate, and may not show light diffusibility.
Therefore, the content of the component (A) is more preferably set to a value in the range of 40 to 300 parts by weight with respect to 100 parts by weight of the component (B), and a value in the range of 50 to 200 parts by weight. More preferably.

(2) Low Refractive Index Polymerizable Compound (2) -1 Type Among the two polymerizable compounds having different refractive indexes, the type of the polymerizable compound having the relatively low refractive index (component (B)) is particularly The main component is not limited, and examples thereof include urethane (meth) acrylate, (meth) acrylic polymer having (meth) acryloyl group in the side chain, (meth) acryloyl group-containing silicone resin, unsaturated polyester resin, and the like. In particular, urethane (meth) acrylate is preferable.
The reason for this is that if it is urethane (meth) acrylate, the difference between the refractive index of the region derived from the component (A) and the refractive index of the region derived from the component (B) can be adjusted more easily. (B) It is because the dispersion | variation in the refractive index of the area | region derived from a component can be suppressed effectively, and the light-diffusion film provided with the predetermined | prescribed internal structure can be obtained more efficiently.
Therefore, in the following, urethane (meth) acrylate as the component (B) will be mainly described.
In addition, (meth) acrylate means both acrylate and methacrylate.

First, urethane (meth) acrylate is (B1) a compound containing at least two isocyanate groups, (B2) a polyol compound, preferably a diol compound, particularly preferably a polyalkylene glycol, and (B3) a hydroxyalkyl (meth). Formed from acrylate.
The component (B) includes an oligomer having a urethane bond repeating unit.
Among these, as the compound containing at least two isocyanate groups as the component (B1), for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate Arocyclic polyisocyanates such as aromatic polyisocyanates such as 1,4-xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, etc. Isocyanates and their biurets, isocyanurates, and adducts that are a reaction with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil (for example, Xylylene diisocyanate Inert based trifunctional adduct), and the like.

Moreover, among the above-mentioned, it is especially preferable that it is an alicyclic polyisocyanate.
This is because, in the case of alicyclic polyisocyanates, compared to aliphatic polyisocyanates, it is easy to provide a difference in the reaction rate of each isocyanate group due to the conformation and the like.
This suppresses that the (B1) component reacts only with the (B2) component, or the (B1) component reacts only with the (B3) component, and the (B1) component is converted into the (B2) component and (B3) It can react reliably with a component and generation | occurrence | production of an extra by-product can be prevented.
As a result, it is possible to effectively suppress variations in the refractive index of the region derived from the component (B) in the predetermined internal structure, that is, the low refractive index region.

Moreover, if it is an alicyclic polyisocyanate, compared with an aromatic polyisocyanate, compatibility with the obtained (B) component and (A) component is reduced to a predetermined range, The structure can be formed more efficiently.
Furthermore, if it is an alicyclic polyisocyanate, compared with an aromatic polyisocyanate, the refractive index of the (B) component obtained can be made small, Therefore The difference with the refractive index of (A) component is shown. The predetermined internal structure with high uniformity of the diffused light within the light diffusion angle region can be formed more efficiently while increasing the light diffusion property more reliably.
Of these alicyclic polyisocyanates, alicyclic diisocyanates containing only two isocyanate groups are preferred.
This is because if it is an alicyclic diisocyanate, it can react quantitatively with the component (B2) and the component (B3) to obtain a single component (B).
As such an alicyclic diisocyanate, isophorone diisocyanate (IPDI) can be particularly preferably mentioned.
This is because an effective difference can be provided in the reactivity of the two isocyanate groups.

Among the components that form urethane (meth) acrylate, examples of the polyalkylene glycol (B2) include polyethylene glycol, polypropylene glycol, polybutylene glycol, and polyhexylene glycol. Particularly preferred is glycol.
This is because polypropylene glycol can be handled without a solvent because of its low viscosity.
Moreover, if it is a polypropylene glycol, when it hardens | cures (B) component, it becomes a favorable soft segment in the said hardened | cured material, and it is because the handling property and mounting property of a light-diffusion film can be improved effectively. is there.
The weight average molecular weight of the component (B) can be adjusted mainly by the weight average molecular weight of the component (B2). Here, the weight average molecular weight of (B2) component is 2,300-19,500 normally, Preferably it is 4,300-14,300, Most preferably, it is 6,300-12,300.

Moreover, as a hydroxyalkyl (meth) acrylate which is a (B3) component among the components which form urethane (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3 -Hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc. are mentioned.
In addition, from the viewpoint of reducing the polymerization rate of the obtained urethane (meth) acrylate and more efficiently forming a predetermined internal structure, hydroxyalkyl methacrylate is more preferable, and 2-hydroxyethyl methacrylate is particularly preferable. Is more preferable.

Moreover, the synthesis | combination of the urethane (meth) acrylate by (B1)-(B3) component can be implemented in accordance with a conventional method.
At this time, the blending ratio of the components (B1) to (B3) is preferably set to a ratio of (B1) component: (B2) component: (B3) component = 1-5: 1: 1-5 in molar ratio. .
The reason for this is that by setting such a blending ratio, one isocyanate group of the component (B1) reacts and binds to the two hydroxyl groups of the component (B2), and two more components (B1) This is because the urethane (meth) acrylate in which the hydroxyl group of the component (B3) reacts with and bonds to the other isocyanate group possessed by each can be synthesized efficiently.
Therefore, the blending ratio of the components (B1) to (B3) is preferably set to a ratio of (B1) component: (B2) component: (B3) component = 1-3: 1: 1-3 in molar ratio. Preferably, the ratio is 2: 1: 2.

(2) -2 Weight average molecular weight Moreover, it is preferable to make the weight average molecular weight of (B) component into the value within the range of 3,000-20,000.
This is because, by setting the weight average molecular weight of the component (B) within a predetermined range, a predetermined difference is caused in the polymerization rate of the component (A) and the component (B), and the copolymerizability of both components is effectively improved. This is because it can be lowered.
As a result, when photocured, a plurality of flakes having a relatively high refractive index derived from the component (A) in a different refractive index region having a relatively low refractive index derived from the component (B) It is possible to efficiently form a predetermined internal structure in which the are arranged.
That is, when the weight average molecular weight of the component (B) is less than 3,000, the polymerization rate of the component (B) is increased to be close to the polymerization rate of the component (A). This is because polymerization may easily occur, and it may be difficult to efficiently form a predetermined internal structure. On the other hand, when the weight average molecular weight of the component (B) exceeds 20,000, the refractive index derived from the component (A) is in a different refractive index region where the refractive index derived from the component (B) is relatively low. It becomes difficult to form a predetermined internal structure in which a plurality of flakes having a relatively high rate are arranged, or the compatibility with the component (A) is excessively reduced, and (A This is because the component may precipitate.
Therefore, the weight average molecular weight of the component (B) is more preferably set to a value within the range of 5,000 to 15,000, and further preferably set to a value within the range of 7,000 to 13,000.
In addition, the weight average molecular weight of (B) component can be measured using a gel permeation chromatography (GPC).

(2) -3 Single use Moreover, although (B) component may use together 2 or more types from which molecular structure and a weight average molecular weight differ, it suppresses the dispersion | variation in the refractive index of the area | region derived from (B) component. From the viewpoint, it is preferable to use only one type.
That is, when a plurality of components (B) are used, the refractive index in the region where the refractive index derived from the component (B) is relatively low varies or increases, and the refractive index derived from the component (A) This is because the difference in refractive index from the relatively high region may become non-uniform or excessively decrease.

(2) -4 Refractive index Moreover, it is preferable to make the refractive index of (B) component into the value within the range of 1.4-1.55.
This is because the difference between the refractive index of the region derived from the component (A) and the refractive index of the region derived from the component (B) is obtained by setting the refractive index of the component (B) within the range. This is because the light diffusing film having a predetermined internal structure can be adjusted more easily and more efficiently.
That is, when the refractive index of the component (B) is less than 1.4, the difference with the refractive index of the component (A) increases, but the compatibility with the component (A) is extremely deteriorated, and a predetermined This is because the internal structure may not be formed. On the other hand, when the refractive index of the component (B) exceeds 1.55, the difference from the refractive index of the component (A) becomes too small, making it difficult to obtain the desired incident angle dependency. Because there is.
Therefore, the refractive index of the component (B) is more preferably set to a value within the range of 1.45 to 1.54, and further preferably set to a value within the range of 1.46 to 1.52.
In addition, the refractive index of (B) component mentioned above means the refractive index of (B) component before hardening by light irradiation.
The refractive index can be measured, for example, according to JIS K0062.

The difference between the refractive index of the component (A) and the refractive index of the component (B) is preferably set to a value of 0.01 or more.
The reason for this is that a light diffusion film having a better incident angle dependency in light transmission and diffusion and a wider light diffusion incident angle region is obtained by setting the difference in refractive index to a value within a predetermined range. Because it can.
That is, when the difference in refractive index is less than 0.01, the angle range in which incident light is totally reflected within a predetermined internal structure is narrowed, so that the opening angle in light diffusion may be excessively narrowed. Because. On the other hand, if the difference in refractive index is an excessively large value, the compatibility between the component (A) and the component (B) may be excessively deteriorated and a predetermined internal structure may not be formed.
Therefore, the difference between the refractive index of the component (A) and the refractive index of the component (B) is more preferably set to a value in the range of 0.05 to 0.5, More preferably, the value is within the range.
In addition, the refractive index of (A) component and (B) component here means the refractive index of (A) component and (B) component before hardening by light irradiation.

(2) -5 Content Further, the content of the component (B) in the composition for light diffusion film is within the range of 10 to 80% by weight with respect to 100% by weight of the total amount of the composition for light diffusion film. It is preferable to use a value.
The reason for this is that when the content of the component (B) is less than 10% by weight, the ratio of the component (B) to the component (A) decreases, and the region derived from the component (B) becomes (A This is because it may be too small compared with the region derived from the component, and it may be difficult to obtain a predetermined internal structure having good incident angle dependency. On the other hand, when the content of the component (B) exceeds 80% by weight, the ratio of the component (B) to the component (A) increases, and the region derived from the component (B) becomes (A) This is because it becomes excessively large compared with the region derived from the components, and conversely, it may be difficult to obtain a predetermined internal structure having good incident angle dependency.
Therefore, it is more preferable to make content of (B) component into the value within the range of 20 to 70 weight% with respect to 100 weight% of the total amount of the composition for light diffusion films, More preferably, the value is within the range.

(3) Photopolymerization initiator Moreover, in the composition for light diffusion films in this invention, it is preferable to contain a photoinitiator as (C) component as needed.
This is because a predetermined internal structure can be efficiently formed when the composition for a light diffusing film is irradiated with an active energy ray by containing a photopolymerization initiator.
Here, the photopolymerization initiator refers to a compound that generates radical species by irradiation with active energy rays such as ultraviolet rays.

Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, and 2,2-dimethoxy-2-phenylacetophenone. 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] 2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4-diethyl Minobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylamine benzoate, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propane and the like Of these, one of them may be used alone, or two or more of them may be used in combination.
In addition, as content in the case of containing a photoinitiator, it is set as the value within the range of 0.2-20 weight part with respect to 100 weight part of total amounts of (A) component and (B) component. Preferably, the value is in the range of 0.5 to 15 parts by weight, and more preferably in the range of 1 to 10 parts by weight.

(4) Other Additives Additives other than the above-described compounds can be appropriately added within a range not impairing the effects of the present invention.
Examples of such additives include antioxidants, ultraviolet absorbers, antistatic agents, polymerization accelerators, polymerization inhibitors, infrared absorbers, plasticizers, diluent solvents, and leveling agents.
In general, the content of such additives is preferably set to a value in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the total amount of the component (A) and the component (B). The value is more preferably in the range of 0.02 to 3 parts by weight, and still more preferably in the range of 0.05 to 2 parts by weight.

3. Step (b): Application Step The step (b) is a step of forming the coating layer 1 by applying the light diffusion film composition to the step sheet 2 as shown in FIG.
Either a plastic film or paper can be used as the process sheet.
Among these, examples of the plastic film include polyester films such as polyethylene terephthalate films, polyolefin films such as polyethylene films and polypropylene films, cellulose films such as triacetyl cellulose films, and polyimide films.
Examples of the paper include glassine paper, coated paper, and laminated paper.
In addition, as a process sheet | seat, since it is excellent in sheet | seat strength and surface smoothness, it is preferable that it is a plastic film.
Moreover, when the process mentioned later is considered, as the process sheet | seat 2, it is more preferable that it is a plastic film excellent in the dimensional stability with respect to a heat | fever or an active energy ray.
As such a plastic film, among those described above, a polyester film, a polyolefin film and a polyimide film are preferably exemplified.

In addition, for the process sheet, a release layer is provided on the application surface side of the composition for light diffusion film in the process sheet in order to easily peel the obtained light diffusion film from the process sheet after photocuring. Is preferred.
Such a release layer can be formed using a conventionally known release agent such as a silicone release agent, a fluorine release agent, an alkyd release agent, or an olefin release agent.
In addition, it is preferable that the thickness of a process sheet | seat is normally set to the value within the range of 25-200 micrometers.

  Examples of the method for applying the light diffusing film composition on the process sheet include conventionally known methods such as knife coating, roll coating, bar coating, blade coating, die coating, and gravure coating. Can be performed.

Moreover, it is preferable to make the film thickness of a coating layer into the value within the range of 80-700 micrometers.
This is because the predetermined internal structure can be formed more efficiently by setting the thickness of the coating layer to a value within this range.
That is, when the film thickness of the coating layer is less than 80 μm, the length of the film in the film thickness direction of the predetermined internal structure to be formed is insufficient, and the incident light that goes straight through the predetermined internal structure increases. This is because it may be difficult to obtain the uniformity of the intensity of the diffused light within the light diffusion angle region. On the other hand, when the thickness of the coating layer exceeds 700 μm, when the coating layer is irradiated with active energy rays to form a predetermined internal structure, photopolymerization is performed by the predetermined internal structure formed initially. This is because it may be difficult to form a desired internal structure due to diffusion of the traveling direction.
Therefore, the thickness of the coating layer is more preferably set to a value within the range of 100 to 500 μm, and further preferably set to a value within the range of 120 to 300 μm.

4). Step (c): Active energy ray irradiation step (1) Active energy ray irradiation preparation step In this step, an active energy ray from an active energy ray light source is incident every azimuth direction prior to an active energy ray irradiation step described later. This is a step of preparing for conversion to an active energy ray whose angle width is controlled to a value within a predetermined range.
When performing this process, as shown in FIG. 8B, a linear light source 125 as an active energy ray light source and an incident angle for adjusting the incident angle width of the active energy ray from the linear light source 125. And the incident angle width adjusting member 200 is disposed between the linear light source 125 and the coating layer 1 and in the active energy ray emission region from the linear light source 125. preferable.
More specifically, as shown in FIG. 8B, the incident angle width adjusting member 200 includes a plurality of plate-like members 210, and the plurality of plate-like members 210 are parallel to each other with their main surfaces facing each other. It is preferable that the main surface is parallel to the vertical direction while being arranged.
The reason for this is that, by performing the active energy ray irradiation preparation step in this manner, the active energy rays from the linear light source are converted into active energy whose incident angle width is controlled to a value within a predetermined range for each azimuth direction. This is because it can be converted into a line and irradiated onto the coating layer.
It should be noted that “a plurality of plate-like members are arranged in parallel with their main surfaces facing each other”, but direct light from a linear light source is a value within a predetermined range of incident angle width for each azimuth angle direction. From the viewpoint of conversion to active energy rays controlled to a substantially constant value, it is sufficient if it is substantially parallel.
Further, “between the linear light source 125 and the coating layer 1 and in the radiation region of active energy rays from the linear light source 125” means, for example, as shown in FIG. When the active energy ray is irradiated vertically downward from above, the light source 125 is vertically below the linear light source 125 and vertically above the coating layer 1.

That is, in order to obtain an elliptical light diffusion film, it is necessary to form a predetermined internal structure as shown in FIGS. 5A to 5C and FIGS. 6A to 6B in the film. However, in order to form such a predetermined internal structure, it is necessary to irradiate the coating layer with an active energy ray whose incident angle width is controlled to a value within a predetermined range for each azimuth angle direction.
More specifically, as shown in FIGS. 9A to 9C, on the surface of the coating layer 1, an arbitrary position located on a region where the illuminance of the active energy ray 60 from the active energy ray light source 125 is maximum. The azimuth angle direction X at which the incident angle width of the active energy ray takes the minimum value θ3 and the azimuth angle direction Y at which the incident angle width of the active energy ray takes the maximum value θ4 at one point R are orthogonal to each other, and In addition, the minimum value θ3 of the incident angle width of the active energy ray needs to be a value of 10 ° or less, and the maximum value θ4 of the incident angle width of the active energy ray needs to be a value in the range of more than 10 ° and 40 ° or less. is there.

Here, FIG. 9 (a) is a plan view when viewed from above the coating layer 1, and FIG. 9 (b) is a side view when viewed from the direction Y in FIG. 9 (a). 3 is a diagram illustrating an incident angle width of an active energy ray in an azimuth angle direction X. FIG.
FIG. 9C is a side view when viewed from the direction X in FIG. 9A, and shows the incident angle width of the active energy ray in the azimuth angle direction Y.
First, “in the surface of the coating layer, the region where the illuminance of the active energy ray from the active energy ray light source is maximum” means a linear light source as the active energy ray light source as shown in FIGS. When 125 is used, it becomes the center line of the distribution of the active energy rays 60 irradiated to the surface of the coating layer 1 substantially linearly.
Therefore, as shown in FIG. 9B, when the active energy ray 60 is irradiated vertically downward from the linear light source 125, the linear light source 125 on the surface of the coating layer 1 in FIG. A projection line vertically below the center line is a region where the illuminance of the active energy ray from the active energy ray light source is maximum.
In addition, for example, when the active energy ray is irradiated from the linear light source toward the diagonally lower right side, the active energy ray light source is in the vicinity of the projected line to the lower right side of the center line of the linear light source on the surface of the coating layer. There is a region where the illuminance of the active energy ray from is maximized.

Next, "at the surface of the coating layer, the azimuth angle direction at which the incident angle width of the active energy ray takes the minimum value at any point located on the region where the illuminance of the active energy ray from the active energy ray light source is maximum 9 (a) to (c), when the linear light source 125 is used as the active energy ray light source, the incident angle width of the active energy ray 60 is minimum as shown in FIG. 9 (b). The azimuth angle direction X takes the value θ3, and the direction is orthogonal to the axial direction of the linear light source 125.
Further, the minimum value θ3 of the incident angle width of the active energy line 60 at the point R as “any one point” is two from the point R to the cross-sectional circle of the linear light source 125 as shown in FIG. The angle formed by the tangent line.

Furthermore, “the azimuth angle direction in which the incident angle width of the active energy ray has a maximum value at any one point on the surface of the coating layer on the region where the illuminance of the active energy ray from the active energy ray light source is maximum” 9A to 9C, when the linear light source 125 is used as the active energy ray light source, as shown in FIG. 9C, the incident angle width of the active energy ray 60 is the maximum value. The azimuth angle direction Y takes θ4, and is the azimuth angle direction orthogonal to the azimuth angle direction X described above.
And the maximum value θ4 of the incident angle width of the active energy line 60 at the point R as “any one point” is a line between the two plate-like members 210 adjacent from the point R as shown in FIG. The angle formed by two tangents to the end on the side of the light source 125.
Thus, the azimuth angle direction X in which the incident angle width of the active energy ray takes the minimum value θ3 and the azimuth angle direction Y in which the incident angle of the active energy ray takes the maximum value θ4 are orthogonal to each other. A predetermined internal structure can be formed well.

Although the case where a linear light source is used as the active energy ray light source has been specifically described above, the active energy ray light source in the present invention is not limited to the linear light source.
In that case, the area where the illuminance of the active energy ray from the active energy ray light source becomes the maximum, while irradiating the active energy ray, installing the illuminance light quantity meter on the process sheet without the coating layer, and moving the process sheet It can also be easily specified by plotting the amount of illuminance.
In addition, regarding the maximum value and the minimum value of the incident angle width of the active energy ray, the incident angle width adjusting member at any one point located on the region where the illuminance of the active energy ray from the active energy ray light source is maximum. It can be specified as the maximum value and the minimum value of the incident angle width of the active energy ray irradiated to any one point without being blocked by the plate-like member or the like.
In addition, the specific method mentioned above is applicable also when a linear light source is used as an active energy ray light source.

In addition, when the minimum value θ3 of the incident angle width of the active energy ray shown in FIG. In the same manner as the above, there are cases where the film does not exhibit any diffusion characteristics. On the other hand, if the minimum value θ3 of the incident angle width of the active energy ray becomes excessively small, the integrated light amount of the active energy ray becomes excessively low, and the productivity may be extremely lowered.
Therefore, on the surface of the coating layer, the minimum value θ3 of the incident angle width of the active energy ray at any one point located on the region where the illuminance of the active energy ray from the active energy ray light source is maximum is set to 0.1-7. A value within the range of ° is more preferable, and a value within the range of 0.5 to 5 ° is even more preferable.

When the maximum incident angle width θ4 of the active energy ray shown in FIG. 9C is 10 ° or less, both the azimuth angle directions X and Y have small incident angle widths, and when parallel light is applied Similarly, an isotropic light diffusion film having a column structure in the film may be obtained. On the other hand, when the maximum value θ4 of the incident angle width of the active energy ray exceeds 40 °, the difference in incident angle width between the azimuth directions X and Y becomes too large, and direct light is applied from the linear light source. As in the case of the case, the film may become an anisotropic light diffusion film having a louver structure in the film.
Therefore, on the surface of the coating layer, the maximum value θ4 of the incident angle width of the active energy ray at an arbitrary point located on the region where the illuminance of the active energy ray from the active energy ray light source is maximum is 12 to 35 °. A value within the range is more preferable, and a value within the range of 15 to 30 ° is even more preferable.

Next, the relationship between the maximum incident angle width θ4 and the elliptical light diffusion will be described with reference to FIG.
That is, FIG. 10 shows a characteristic curve in which the horizontal axis represents the maximum incident angle width θ4 (°) of the active energy ray and the vertical axis represents θ2 ′ / θ2 (−).
Here, as shown in FIGS. 7B to 7C, θ2 is the opening angle (°) of the diffused light in the major axis direction in the elliptical light diffusion, and θ2 ′ is the elliptical light. It is an opening angle (°) of diffused light in the minor axis direction in diffusion.

As can be understood from this characteristic curve, when θ4 becomes a value of 10 ° or less, the value of θ2 ′ / θ2 becomes excessively large, and light diffusion characteristics close to isotropic light diffusion are exhibited, while θ4 is 40 °. When it exceeds the value, the value of θ2 ′ / θ2 becomes excessively small, and it can be seen that light diffusion characteristics close to anisotropic light diffusion are exhibited.
And when (theta) 4 is a value within the range of more than 10 degrees and 40 degrees or less, it turns out that elliptical light diffusion which is a light diffusion characteristic between isotropic light diffusion and anisotropic light diffusion expresses.
Further, in the range of θ4 exceeding 10 ° and 40 ° or less, the value of θ2 ′ / θ2 also changes with the change of the value of θ4. It is understood that the ellipticity of the elliptical light diffusion can be effectively controlled by adjusting.

Moreover, as shown to Fig.11 (a), although the space | interval L1 in the some plate-shaped member 210 is based on the length L3 of the vertical direction in the plate-shaped member 210, etc., it is set as the value within the range of 1-1000 mm. It is preferable.
The reason for this is that by setting the interval L1 in the plurality of plate-like members 210 to a value within such a range, the active energy rays from the linear light source are more effectively incident in the predetermined angle range for each azimuth direction. This is because it can be converted into an active energy ray controlled to a value within the range.
That is, when the interval L1 between the plurality of plate-like members becomes a value less than 1 mm, the maximum value θ4 of the incident angle width of the active energy ray becomes a value of 10 ° or less. This is because the angle width becomes an isotropic light diffusion film having a column structure in the film, as in the case where parallel light is applied. On the other hand, if L1 is too small, heat may be accumulated between the plate-like members and the plate-like member may be distorted. On the other hand, when the distance L1 between the plurality of plate-like members is a value exceeding 1000 mm, the maximum value θ4 of the incident angle width of the active energy ray is a value exceeding 40 °. This is because the difference in incident angle width becomes so large that an anisotropic light diffusing film having a louver structure may be formed in the film as in the case of direct light from a linear light source.
Therefore, it is more preferable to set the distance L1 between the plurality of plate-like members to a value within the range of 5 to 750 mm, and it is even more preferable to set the value within the range of 10 to 500 mm.
In FIG. 11A, the number of plate-like members is four, but this is merely an example, and the actual number of plate-like members is the width of the coating layer to be irradiated with the active energy ray. Or, it is determined by various conditions such as the interval L1 in the plurality of plate-like members.

In addition, the width L2 of the plate-like member 210 is not particularly limited, but is usually preferably a value in the range of 1 to 5000 mm, and more preferably a value in the range of 10 to 1000 mm. .
In addition, it is preferable that the diameter seen from the axial direction of the linear light source 125 is usually a value within the range of 5 to 100 mm.

Moreover, it is preferable to make the thickness of the plate-shaped member 210 into the value within the range of 0.1-5 mm.
The reason for this is that the thickness of the plate-like member is set to a value within this range, so that the influence of the shadow caused by the incident angle width adjusting member is suppressed and the distortion of the plate-like member due to the active energy ray is also effective. This is because it can be suppressed.
That is, if the thickness of the plate-like member is less than 0.1 mm, distortion may easily occur due to active energy rays. On the other hand, when the thickness of the plate-shaped member exceeds 5 mm, the influence of the shadow of the plate-shaped member becomes large, and it may be difficult to suppress uneven illuminance in the coating layer.
Therefore, the thickness of the plate-like member is more preferably set to a value within the range of 0.5 to 2 mm, and further preferably set to a value within the range of 0.7 to 1.5 mm.

  Further, the material of the plate-like member 210 is not particularly limited as long as it can absorb light having a low degree of parallelism with the plate-like member 210. For example, an Alster steel plate with heat-resistant black coating is used. be able to.

Moreover, it is preferable to arrange the incident angle width adjusting member 200 in a direction in which the plate member intersects the axial direction of the linear light source.
Furthermore, it is more preferable that the incident angle width adjusting member 200 is disposed in a direction in which the plate-like member 210 is orthogonal to the axial direction of the linear light source 125 when viewed from above the coating layer.
The reason for this is that by arranging the incident angle width adjusting member in this way, the maximum value θ4 of the incident angle width of the active energy ray can be set even if the values of the intervals L1 in the plurality of plate-like members are the same. This is because it can be made smaller.
That is, when the plate-like member and the axial direction of the linear light source are not orthogonal, the interval between the plate-like members viewed in the axial direction of the linear light source is the same L1 value as compared to the case where they are orthogonal. growing.
And if the space | interval of a plate-shaped member becomes large, since the capability to parallelize an active energy ray will become weak, (theta) 4 becomes a big value.
In other words, if the plate member and the axial direction of the linear light source are not orthogonal, the value of L1 must be reduced in order to obtain the same value of θ4 as when orthogonal.
Then, as the value of L1 is decreased, heat is accumulated between the plate-like members and the like, and there is a problem that the plate-like member is likely to be distorted.

Moreover, as shown in FIG.11 (b), although the length L3 of the up-down direction in a plate-shaped member is based on the space | interval L1 in the some plate-shaped member 210, etc., it is set as the value within the range of 10-1000 mm. preferable.
The reason for this is that by setting the vertical length L3 of the plate-like member to a value within this range, the active energy rays from the linear light source can be more effectively given a predetermined incident angle width for each azimuth direction. This is because it can be converted into an active energy ray controlled to a value within the range.
That is, when the length L3 becomes a value less than 10 mm, the maximum value θ4 of the incident angle width of the active energy ray exceeds 40 °, and thus the difference in incident angle width between the azimuth angle directions X and Y This is because the film becomes too large and may become an anisotropic light diffusion film having a louver structure in the film, as in the case of direct light from a linear light source. On the other hand, when the length L3 exceeds 1000 mm, the maximum incident angle width θ4 of the active energy ray is 10 ° or less, and therefore the incident angle width is small in both the azimuth directions X and Y. This is because an isotropic light diffusion film having a column structure in the film may be formed as in the case where parallel light is applied.
Therefore, the length L3 in the vertical direction of the plate-like member is more preferably set to a value within the range of 20 to 750 mm, and further preferably set to a value within the range of 50 to 500 mm.
11B is a side view of the incident angle width adjusting member 200a shown in FIG. 11A viewed from the axial direction of the linear light source 125. FIG.

Moreover, as shown in FIG.11 (b), the distance L4 between the upper end of the incident angle width adjustment member 200 and the lower end of the linear light source 125 shall be made into the value within the range of 0.1-1000 mm. preferable.
The reason for this is that by setting the distance L4 to a value within this range, the active energy ray from the linear light source is more effectively controlled to a value within a predetermined range for the incident angle width for each azimuth direction. This is because the coating layer can be irradiated with a sufficient amount of active energy rays while being converted into active energy rays.
That is, when the distance L4 is less than 0.1 mm, the incident angle width adjusting member becomes too close to the linear light source, and the plate member may be distorted by heat. On the other hand, when the distance L4 exceeds 1000 mm, the coating layer is too far from the linear light source, and the active energy ray incident on the coating layer may become too weak.
Therefore, it is more preferable to set the distance L4 between the upper end of the incident angle width adjusting member and the lower end of the linear light source to a value within the range of 0.5 to 500 mm, and a value within the range of 1 to 100 mm. More preferably.

Moreover, as shown in FIG.11 (b), it is preferable to make the distance L5 between the lower end of an incident angle width adjustment member and the surface of an application layer into the value within the range of 0.1-1000 mm.
The reason for this is that by setting the distance L5 within the range, the active energy ray from the linear light source can be more effectively azimuthed while suppressing the influence of the shadow by the incident angle width adjusting member more effectively. This is because the incident angle width can be converted into an active energy ray controlled to a value within a predetermined range for each angular direction.
That is, when the distance L5 is less than 0.1 mm, the influence of the shadow of the plate member is excessively increased, and the lower end of the incident angle width adjusting member and the surface of the coating layer are caused by slight vibration during irradiation. This is because there may be cases where the contact occurs. On the other hand, when the distance L5 exceeds 1000 mm, the coating layer is too far from the linear light source, and the active energy rays incident on the coating layer may be excessively weakened.
Therefore, it is more preferable to set the distance L5 between the lower end of the incident angle width adjusting member and the surface of the coating layer to a value in the range of 0.5 to 500 mm, and to a value in the range of 1 to 100 mm. More preferably.
Heretofore, only the plate-shaped members arranged in parallel as the incident angle width adjusting member are described, and only the linear light source is described as the active energy ray light source, but it is important in manufacturing the elliptical light diffusion film. The point is that θ3 and θ4 become values within a specified range.
Therefore, for example, an assembly of rectangular cylinders may be used as the incident angle width adjusting member, and a surface light source may be used as the active energy ray light source to realize θ3 and θ4 within a specified range.
Furthermore, without using an incident angle width adjusting member, a parallel light source is used as an active energy ray light source, and this is diffused by an elliptical light diffusing element such as an elliptical light diffusing film to realize θ3 and θ4 within a specified range. May be.

(2) Active energy ray irradiating step As shown in FIG. 8C, this step is a step of irradiating the coating layer 1 with active energy rays while moving the coating layer 1 normally. As shown in FIGS. 9A to 9C, the activity at an arbitrary point R located on the region where the illuminance of the active energy ray 60 from the active energy ray light source 125 is maximum on the surface of the coating layer 1. The azimuth angle direction X in which the incident angle width of the energy ray takes the minimum value θ3 and the azimuth angle direction Y in which the incident angle width of the active energy ray takes the maximum value θ4 are orthogonal to each other, and the incident of the active energy ray In this step, the minimum value θ3 of the angle width is set to a value of 10 ° or less, and the maximum value θ4 of the incident angle width of the active energy ray is set to a value in the range of more than 10 ° and 40 ° or less.
More specifically, as shown in FIG. 12A, an ultraviolet irradiation device 120 in which a condensing cold mirror 122 is provided on a linear ultraviolet lamp 125 (for example, in the case of a commercial product, an eye graphics The active energy ray 50 is irradiated to the coating layer 1 formed on the process sheet 2 via the incident angle width adjusting member 200 by ECS-4011GX manufactured by Co., Ltd.
Further, it is preferable to further improve the parallelism of the active energy rays 50 by providing light shielding members 123 a and b between the incident angle width adjusting member 200 and the coating layer 1.
Furthermore, from the viewpoint of improving the parallelism of the active energy ray 50, a light shielding plate 121 is provided between the linear light source 125 and the incident angle width adjusting member 200, and the active energy ray 50 is directly emitted from the linear light source 125. It is also preferable to use only.
The linear ultraviolet lamp 125, when viewed from above the coating layer 1, is usually a value within a range of −80 to 80 ° with a direction (0 °) perpendicular to the moving direction of the coating layer 1 as a reference (0 °). It is preferably installed so as to have a value in the range of −50 to 50 °, particularly preferably in the range of −30 to 30 °.

In addition, as the irradiation angle of the active energy ray, as shown in FIG. 12B, the irradiation angle θ5 when the normal angle to the surface of the coating layer 1 is 0 ° is usually −80 to 80 °. A value within the range is preferable.
This is because, when the irradiation angle is a value outside the range of −80 to 80 °, the influence of reflection on the surface of the coating layer 1 becomes large, and it becomes difficult to form a predetermined internal structure. Because there is.
Further, the irradiation angle θ5 preferably has a width (irradiation angle width) θ5 ′ of 1 to 80 °.
This is because, when the irradiation angle width θ5 ′ is a value less than 1 °, the moving speed of the coating layer must be excessively decreased, and the production efficiency may be decreased. On the other hand, if the irradiation angle width θ5 ′ exceeds 80 °, the irradiation light may be excessively dispersed and it may be difficult to form a predetermined internal structure.
Therefore, the irradiation angle width θ5 ′ of the irradiation angle θ5 is more preferably set to a value within the range of 2 to 45 °, and further preferably set to a value within the range of 5 to 20 °.
In addition, when it has irradiation angle width | variety (theta) 5 ', let the angle of the intermediate position just be irradiation angle (theta) 5.

Moreover, it is preferable to make the peak illumination intensity in the surface of the coating layer in active energy ray irradiation into the value within the range of 0.01-50 mW / cm < ² >.
This is because a predetermined internal structure can be more stably formed in the film by setting the peak illuminance in active energy ray irradiation to a value within such a range.
That is, when the peak illuminance is less than 0.01 mW / cm ² , it may be difficult to clearly form a predetermined internal structure. On the other hand, when the peak illuminance is a value exceeding 50 mW / cm ² , it is estimated that the curing rate becomes too fast, and the predetermined internal structure may not be clearly formed.
Therefore, it is more preferable to set the peak irradiance on the surface of the coating layer in the active energy ray irradiation within a range of 0.05~30mW / cm ^2, to a value within the range of 0.1~40mW / cm ² More preferably.

Moreover, it is preferable to make the integrated light quantity in the surface of the coating layer in active energy ray irradiation into the value within the range of 1-1000 mJ / cm < ² >.
This is because the predetermined internal structure can be more stably formed in the film by setting the integrated light quantity in the active energy ray irradiation to a value within this range.
That is, when the integrated light quantity is less than 1 mJ / cm ² , it may be difficult to sufficiently extend the predetermined internal structure from the top to the bottom. On the other hand, when the integrated light amount exceeds 1000 mJ / cm ² , the resulting light diffusion film may be colored.
Therefore, it is more preferable to the integrated amount of light at the surface of the coating layer in the active energy ray irradiation within a range of 2~500mJ / cm ^2, still more preferably a value within the range of 5 to 200 mJ / cm ² .

Moreover, it is preferable to make the moving speed of a coating layer into the value within the range of 0.1-10 m / min.
The reason for this is that an elliptical light diffusion film can be efficiently produced by setting the moving speed of the coating layer to a value within this range.
That is, when the moving speed of the coating layer is less than 0.1 m / min, the production efficiency of the elliptical light diffusion film may be extremely reduced. On the other hand, when the moving speed of the coating layer exceeds 10 m / min, the integrated light quantity becomes insufficient, and it may be difficult to sufficiently extend the predetermined internal structure from above to below. Because.
Therefore, the moving speed of the coating layer is more preferably set to a value within the range of 0.2 to 5 m / min, and further preferably set to a value within the range of 0.5 to 3 m / min.

Moreover, it is also preferable to irradiate an active energy ray with the active energy ray permeable sheet laminated on the upper surface of the coating layer.
The reason for this is that by laminating the active energy ray transmissive sheet, the influence of oxygen inhibition can be effectively suppressed and a predetermined internal structure can be formed more efficiently.
That is, by laminating an active energy ray transmissive sheet on the upper surface of the coating layer, the coating layer efficiently penetrates the sheet while stably preventing the upper surface of the coating layer from coming into contact with oxygen. This is because active energy rays can be irradiated on the surface.
In addition, as an active energy ray permeable sheet, if the active energy ray can permeate | transmit among the process sheets described in the process (b) (application | coating process), it can use without a restriction | limiting in particular.

In addition to the active energy ray irradiation in the step (c), it is preferable to further irradiate the active energy ray so that the integrated light quantity that the coating layer is sufficiently cured is obtained.
The active energy rays at this time are intended to sufficiently cure the coating layer, and therefore, random light (scattered light) whose individual vectors are not controlled should be used instead of parallel light or the like. preferable.

5. Light Diffusing Film The light diffusing film obtained by the production method of the present invention is a light diffusing film characterized in that incident light is diffused in an elliptical shape with respect to a plane parallel to the light diffusing film.
Hereinafter, such an elliptical light diffusion film will be described in detail.

(1) Refractive index In a predetermined internal structure, the difference between the refractive index of a flaky material having a relatively high refractive index and the refractive index of a different refractive index region having a relatively low refractive index is a value of 0.01 or more. It is preferable that
This is because the difference in refractive index is set to a value of 0.01 or more, so that incident light is stably reflected within a predetermined internal structure, and the incident angle dependency and the diffused light opening angle are further improved. It is because it can be made.
That is, when the difference in refractive index is less than 0.01, the angle range at which incident light is totally reflected within a predetermined internal structure is narrowed. This is because the opening angle may be excessively narrow.
Therefore, the difference between the refractive index of the flaky material having a relatively high refractive index in the predetermined internal structure and the refractive index of the different refractive index region having a relatively low refractive index may be set to a value of 0.05 or more. More preferably, the value is more preferably 0.1 or more.
In addition, although the difference of refractive index is so preferable that it is large, from a viewpoint of selecting the material which can form a predetermined internal structure, about 0.3 is considered to be an upper limit.

(2) Form of flakes The elliptical light diffusion film obtained by the production method of the present invention has a film surface as shown in FIGS. 5 (a) to 5 (c) and FIGS. 6 (a) to 6 (b). It has a predetermined internal structure composed of a plurality of flaky objects having a relatively high refractive index and arranged in one arbitrary direction along a different refractive index region having a relatively low refractive index.
However, unlike the conventional louver structure or column structure, the predetermined internal structure is estimated to change along the film thickness direction, as shown in FIG. Has not yet been confirmed.
Therefore, only the contents that have been confirmed at this point will be described here.
That is, as shown in the photograph of the oblique cut surface of 45 ° in FIG. 6B, the flaky material in the cross section parallel to the film surface on the film surface side of the elliptical light diffusion film has a length of several μm and a width of However, it is 2 to 4 μm like the plate-like region in the conventional louver structure, and such flaky objects are arranged along the length direction at intervals of several tens of μm.
On the other hand, the flaky material in the cross section parallel to the film surface on the film bottom side has grown to a length of several tens of μm or more, but the width is maintained at 2 to 4 μm which is almost the same as the surface side. doing.

(3) Film thickness Moreover, it is preferable to make the film thickness of the light-diffusion film obtained by the manufacturing method of this invention into the value within the range of 50-500 micrometers.
This is because when the film thickness of the light diffusing film is less than 50 μm, the light traveling straight in the predetermined internal structure increases, and it may be difficult to exhibit light diffusibility. On the other hand, when the film thickness of the light diffusing film exceeds 500 μm, when the active energy ray is irradiated to the composition for the light diffusing film to form a predetermined internal structure, This is because the traveling direction of photopolymerization is diffused by the internal structure, and it may be difficult to form a desired internal structure.
Therefore, the film thickness of the light diffusion film is more preferably set to a value within the range of 80 to 350 μm, and further preferably set to a value within the range of 100 to 260 μm.

(4) Adhesive layer Moreover, the light-diffusion film obtained by the manufacturing method of this invention may be equipped with the adhesive layer for laminating | stacking with respect to a to-be-adhered body in the single side | surface or both surfaces.
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited, and conventionally known pressure-sensitive adhesives such as acrylic, silicone, urethane, and rubber can be used.

(5) Elliptical light diffusion The light diffusing film obtained by the production method of the present invention is characterized by having an elliptical light diffusing characteristic. When the angle is θ2 (°) and the opening angle of diffused light in the minor axis direction is θ2 ′ (°), it is preferable that the following relational expression (1) is satisfied.
0.2 ≦ θ2 ′ / θ2 ≦ 0.9 (1)
This is because the applicability to a rectangular display can be further improved as long as the elliptical light diffusion satisfies the relational expression (1).
That is, when θ2 ′ / θ2 is less than 0.2, it becomes close to anisotropic light diffusion, and it may be difficult to brighten the entire display surface. On the other hand, when θ2 ′ / θ2 exceeds 0.9, it is close to isotropic light diffusion, and there is a case where useless diffused light may exist in a rectangular display.
Note that the value of θ2 ′ / θ2 can be changed by adjusting the value of the maximum incident angle width θ4 of the active energy ray, and the ellipticity of elliptical diffusion can be changed according to the viewing environment of the display. Can be controlled.

  Hereinafter, with reference to an Example, the manufacturing method of the light-diffusion film of this invention, etc. are demonstrated in detail.

[Example 1]
1. Synthesis of component (B) In a container, 2 mol of isophorone diisocyanate (IPDI) as component (B1) with respect to 1 mol of polypropylene glycol (PPG) having a weight average molecular weight of 9,200 as component (B2), And after accommodating 2 mol of 2-hydroxyethyl methacrylate (HEMA) as a (B3) component, it was made to react according to a conventional method, and the polyether urethane methacrylate of the weight average molecular weight 9,900 was obtained.

In addition, the weight average molecular weight of polypropylene glycol and polyether urethane methacrylate is a polystyrene conversion value measured according to the following conditions by gel permeation chromatography (GPC).
GPC measurement device: manufactured by Tosoh Corporation, HLC-8020
-GPC column: manufactured by Tosoh Corporation (hereinafter, described in order of passage)
TSK guard column HXL-H
TSK gel GMHXL (× 2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C.

2. Preparation of composition for light diffusing film Next, 100 parts by weight of polyether urethane methacrylate having a weight average molecular weight of 9,900 as the obtained component (B) is represented by the following formula (3) as the component (A). O-Phenylphenoxyethoxyethyl acrylate having a molecular weight of 268 (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A-LEN-10) and 10 parts by weight of 2-hydroxy-2-methylpropiophenone as component (C) Then, the mixture was heated and mixed under conditions of 80 ° C. to obtain a composition for light diffusion film. The refractive indexes of the components (A) and (B) were measured according to JIS K0062 using an Abbe refractometer (Atago Co., Ltd., Abbe refractometer DR-M2, Na light source, wavelength: 589 nm). , 1.58 and 1.46, respectively.

3. Application of composition for light diffusion film Next, the obtained composition for light diffusion film was applied to a film-like transparent polyethylene terephthalate film (hereinafter referred to as PET) as a process sheet, and the film thickness was 200 μm. A coating layer was obtained.

4). Arrangement of Incident Angle Width Adjusting Member Next, ultraviolet light in which a condensing cold mirror is attached to a linear high-pressure mercury lamp (diameter 25 mm, length 0.4 m, output 4.5 kW) as shown in FIG. A linear ultraviolet lamp comprising an irradiation device (ECS-4011GX, manufactured by Eye Graphics Co., Ltd.) was prepared.
Next, as shown in FIG. 8B, an incident angle width adjusting member formed by arranging a plurality of plate-like members in parallel was arranged between the linear ultraviolet lamp and the coating layer.
At this time, when viewed from above the coating layer, the incident angle width adjusting member was arranged so that an acute angle formed by the moving direction of the coating layer and the extending direction of the plate-like member was 0 °.
Further, the interval (L1 in FIG. 11A) between the plurality of plate-like members in the incident angle width adjusting member is 20 mm, the width of the plate-like member (L2 in FIG. 11A) is 150 mm, and the thickness of the plate-like member. Was 1 mm, and the material was Ulster steel with heat-resistant black paint.
Further, the length from the upper end to the lower end of the incident angle width adjusting member (L3 in FIG. 11B) is 70 mm, and the distance between the upper end of the incident angle width adjusting member and the lower end of the linear ultraviolet lamp ( L4) in FIG. 11B was 250 mm, and the distance between the lower end of the incident angle width adjusting member and the surface of the coating layer (L5 in FIG. 11B) was 180 mm.
The linear ultraviolet lamp emits active energy rays (ultraviolet rays) so that the moving direction of the coating layer and the major axis direction of the linear ultraviolet lamp are orthogonal to each other and vertically downward from the ultraviolet lamp. Arranged to be irradiated.
Therefore, the projection line vertically below the center line of the ultraviolet lamp on the surface of the coating layer is a region where the illuminance of the active energy ray (ultraviolet light) from the ultraviolet lamp is maximized.

5. Irradiation of ultraviolet rays Next, by irradiating ultraviolet rays from a linear ultraviolet lamp via an incident angle width adjusting member, at any one point located on the above-described region where the illuminance of ultraviolet rays is maximized on the surface of the coating layer, When viewed from the axial direction of the linear ultraviolet lamp, the incident angle width of the ultraviolet ray takes 1.4 ° as the minimum value (θ3 in FIG. 9B), and the movement of the coating layer is perpendicular to this. When viewed from the direction, the coating layer was irradiated with ultraviolet rays through the release film so that the incident angle width of the ultraviolet rays was 16 ° as the maximum value (θ4 in FIG. 9C).
As a result, a light diffusion film having a film thickness of 193 μm was obtained.
At that time, the peak illuminance on the surface of the release film was 2.46 mW / cm ² , the integrated light amount was 23.49 mJ / cm ² , the lamp height was 500 mm, and the moving speed of the coating layer was 0.6 m / min.
In addition, the film thickness of the light-diffusion film was measured using the constant-pressure thickness measuring device (Takara Seisakusho Co., Ltd. product, Teclock PG-02J).

Moreover, it confirmed that the obtained light-diffusion film was a light-diffusion film whose inclination | tilt angle of a flaky material is 0 degree.
Moreover, the cross-sectional photograph of the obtained light-diffusion film is shown to Fig.13 (a)-(c).
That is, FIG. 13 (a) is a cross-sectional photograph when the film is cut at a surface having an inclination of 45 ° with respect to the film surface as shown in FIG. 6 (a), and FIG. FIG. 13C is a cross-sectional photograph when the film is cut in a plane parallel to the moving direction of the layers and perpendicular to the film plane, and FIG. 13C is a plane perpendicular to the cut plane in FIG. It is a cross-sectional photograph at the time of cutting.

6). Evaluation (1) Light reception angle-relative luminance chart of diffused light The light reception angle-relative luminance chart of the obtained light diffusion film was measured.
That is, light of θ1 = 0 ° in FIG. 7B was incident on the obtained light diffusion film.
Next, using a variable angle colorimeter (VC-2 manufactured by Suga Test Instruments Co., Ltd.), a light receiving angle-relative luminance chart of diffused light in a direction parallel to the moving direction of the coating layer and a direction perpendicular thereto. Got.
That is, as shown in FIGS. 14A to 14B, the horizontal axis represents the light diffusion angle (°) of the diffused light diffused by the light diffusion film, and the vertical axis represents the relative intensity (−) of the diffused light. A light receiving angle-relative luminance chart was obtained.
Here, the light reception angle-relative luminance chart A shown in FIG. 14A corresponds to the diffused light in the direction parallel to the moving direction of the coating layer, and the light reception angle-relative luminance chart shown in FIG. B corresponds to the diffused light in the direction orthogonal thereto.
Further, θ2 based on the half-value width of the light reception angle-relative luminance chart A (open angle of diffused light in the major axis direction in the elliptical light diffusion) is 28 °, and θ2 based on the half-value width of the light reception angle-relative luminance chart B. '(Open angle of diffused light in the minor axis direction in elliptical light diffusion) was 16 °, and θ2' / θ2 was 0.57.

(2) Photo of diffused light Photo of diffused light in the obtained light diffusion film was taken.
That is, the light diffusion film obtained was incident and diffused with the light of θ1 = 0 ° in FIG. 7B, and a photograph of the diffused light was taken. The obtained photograph is shown in FIG. 15 (a), and a diagram generated from the photograph is shown in FIG. 15 (b).
From these photographs and figures, the diffusion of diffused light is an elliptical shape having a major axis (L) of 12.5 mm, a minor axis (S) of 7.0 mm, and S / L = 0.56 in a plane parallel to the film. Was confirmed.
Moreover, the diffusion condition of the diffused light confirmed from the photograph and the figure was consistent with the light diffusion characteristic indicated by the measured light receiving angle-relative luminance chart.

[Comparative Example 1]
In Comparative Example 1, ultraviolet rays were irradiated from a linear ultraviolet lamp without using an incident angle width adjusting member.
Thereby, when viewed from the axial direction of the linear ultraviolet lamp at an arbitrary point located on the surface of the coating layer where the illuminance of ultraviolet rays is maximized, the incident angle width of ultraviolet rays is the minimum value ( The angle of incidence angle of ultraviolet rays is the maximum value (θ4 in FIG. 9C) when viewed from the moving direction of the coating layer, which is orthogonal to θ3) in FIG. 9B. ) Was irradiated with ultraviolet rays through the release film so as to take 44 °.
Further, the peak illuminance on the surface of the release film at that time is 7.42 mW / cm ² , the integrated light quantity is 21 mJ / cm ² , the moving speed of the coating layer is 2 m / min, and other conditions are the same as in Example 1. did.
Moreover, the cross-sectional photograph of the obtained light-diffusion film is shown to Fig.16 (a)-(c).
That is, FIG. 16 (a) is a cross-sectional photograph when the film is cut at a surface having an inclination of 45 ° with respect to the film surface as shown in FIG. 6 (a), and FIG. FIG. 16C is a cross-sectional photograph when the film is cut in a plane parallel to the moving direction of the coating layer and perpendicular to the film surface, and FIG. 16C is a plane perpendicular to the cut surface in FIG. It is a cross-sectional photograph at the time of cut | disconnecting a film.
Moreover, the light reception angle-relative brightness | luminance chart in the light-diffusion film obtained to Fig.17 (a)-(b) is shown.
Here, the light reception angle-relative luminance chart A shown in FIG. 17A corresponds to the diffused light in the direction parallel to the moving direction of the coating layer, and the light reception angle-relative luminance chart shown in FIG. B corresponds to the diffused light in the direction orthogonal thereto.
Further, θ2 based on the half value width of the light receiving angle-relative luminance chart A is 25 °, θ2 ′ based on the half value width of the light receiving angle-relative luminance chart B is 4 °, and θ2 ′ / θ2 is 0.16. there were.
Furthermore, the photograph which shows the diffused condition of the diffused light in the light-diffusion film obtained in Fig.18 (a) is shown, and the diagram which arose from this photograph is shown in FIG.18 (b).
From these photographs and figures, the diffusion of diffused light is a rod shape having a major axis (L) of 11.1 mm, a minor axis (S) of 1.7 mm, and S / L = 0.16 in a plane parallel to the film. This was confirmed to be anisotropic light diffusion.
Further, the diffusion state of the diffused light confirmed from the photograph and the figure was consistent with the light diffusion characteristic indicated by the measured light reception angle-relative luminance spectrum.

[Comparative Example 2]
In Comparative Example 2, instead of the incident angle width adjusting member, two light shielding plates for allowing only a part of the ultraviolet rays in the axial direction of the linear ultraviolet lamp to pass downward are arranged in the vicinity of the ultraviolet lamp and vertically below. In addition, while being arranged in parallel with the coating layer with a predetermined interval, the ultraviolet rays from the linear ultraviolet lamp were adjusted so as to be almost parallel light, and then irradiated with ultraviolet rays.
As a result, when viewed from the axial direction of the linear ultraviolet lamp at an arbitrary point on the surface of the coating layer, the incident angle width of the ultraviolet ray is 1.4 ° as the minimum value (θ3 in FIG. 9B). Then, when viewed from the moving direction of the coating layer, which is a direction orthogonal to this, the ultraviolet ray incident angle width is 2.2 ° as the maximum value (θ4 in FIG. 9 (c)). The coating layer was irradiated with ultraviolet rays.
In this case, the peak illuminance on the surface of the release film was 0.36 mW / cm ² , the integrated light amount was 43.9 mJ / cm ² , the moving speed of the coating layer was 0.05 m / min, and other conditions were as in Example 1. And the same.
Moreover, the cross-sectional photograph of the obtained light-diffusion film is shown to Fig.19 (a)-(c).
That is, FIG. 19 (a) is a cross-sectional photograph when the film is cut at a surface having an inclination of 45 ° with respect to the film surface as shown in FIG. 6 (a), and FIG. FIG. 19C is a cross-sectional photograph of the film cut along a plane parallel to the moving direction of the coating layer and perpendicular to the film plane, and FIG. 19C is a plane perpendicular to the cut plane in FIG. It is a cross-sectional photograph at the time of cut | disconnecting a film.
Moreover, the light reception angle-relative brightness | luminance chart in the light-diffusion film obtained to Fig.20 (a)-(b) is shown.
Here, the light reception angle-relative luminance chart A shown in FIG. 20A corresponds to the diffused light in the direction parallel to the moving direction of the coating layer, and the light reception angle-relative luminance chart shown in FIG. B corresponds to the diffused light in the direction orthogonal thereto.
Further, θ2 based on the half value width of the light receiving angle-relative luminance chart A is 26 °, θ2 ′ based on the half value width of the light receiving angle-relative luminance chart B is 25 °, and θ2 ′ / θ2 is 0.96. there were.
Furthermore, the photograph which shows the diffusion condition of the diffused light in the light-diffusion film obtained in Fig.21 (a) is shown, and the diagram which arose from this photograph is shown in FIG.21 (b).
From these photographs and figures, it was confirmed that isotropic light diffusion.
From these photographs and drawings, the diffusion of the diffused light is a circular shape having a major axis (L) of 11.5 mm, a minor axis (S) of 11.1 mm, and S / L = 0.96 in a plane parallel to the film. From this, it was confirmed that the light is isotropically diffused.
Moreover, the diffusion condition of the diffused light confirmed from the photograph and the figure was consistent with the light diffusion characteristic indicated by the measured light receiving angle-relative luminance chart.

As described above in detail, according to the present invention, when the active energy ray is irradiated onto the coating layer, the active energy ray whose incident angle width is controlled to a value within a predetermined range for each azimuth angle direction. , It is possible to obtain a light diffusing film capable of diffusing incident light in an elliptical shape with respect to a plane parallel to the light diffusing film.
As a result, a light diffusion film excellent in applicability to a rectangular display can be efficiently provided.
Therefore, the light diffusing film manufacturing method and the light diffusing film of the present invention include a light control film in a reflection type liquid crystal device, a light viewing film used for a viewing angle control film, a viewing angle widening film, a projection screen, and the like. It is expected to contribute significantly to the improvement of manufacturing efficiency and the quality improvement of these products.

1: coating layer, 2: process sheet, 10: anisotropic light diffusion film, 12: plate-like region having a relatively high refractive index, 13: louver structure, 14: plate-like region having a relatively low refractive index, 20: An isotropic light diffusing film, 22: a columnar object having a relatively high refractive index, 23: a column structure, 24: a region having a relatively low refractive index, 30: an elliptical light diffusing film, and 32: a relatively refractive index. High flaky material, 33: predetermined internal structure, 34: region having a relatively low refractive index, 50: active energy ray from the active energy ray light source, 60: incident angle width within a predetermined range for each azimuth direction Active energy rays controlled to values of: 121: light shielding plate, 122: cold mirror for condensing, 123: light shielding member, 125: linear light source, 200: incident angle width adjusting member, 210: plate member

Claims (11)

The manufacturing method of the light-diffusion film characterized by including the following process (a)-(c).
(A) Step of preparing a composition for light diffusion film (b) Step of applying the composition for light diffusion film to a step sheet and forming a coating layer (c) Active energy rays for the coating layer Irradiating
On the surface of the coating layer, at an arbitrary point located on a region where the illuminance of the active energy ray from the active energy ray light source is maximum, an azimuth angle direction in which the incident angle width of the active energy ray takes a minimum value; The azimuth angle direction in which the incident angle width of the active energy ray takes a maximum value is orthogonal, and
While the minimum value of the incident angle width of the active energy ray is a value of 10 ° or less,
The maximum value of the incident angle width of the active energy ray is set to a value in the range of more than 10 ° and 40 ° or less.   In the step (c), a linear light source as the active energy ray light source and an incident angle width adjusting member for adjusting an incident angle width of an active energy ray from the linear light source are used, and the incident The light diffusion film according to claim 1, wherein an angle width adjusting member is disposed between the linear light source and the coating layer and in a radiation region of active energy rays from the linear light source. Manufacturing method.   The incident angle width adjustment member is composed of a plurality of plate-like members, the plurality of plate-like members are arranged in parallel with each main surface facing each other, and the main surface is parallel to the vertical direction. The method for producing a light diffusing film according to claim 1 or 2.   The manufacturing method of the light-diffusion film of Claim 3 which makes the space | interval in the said adjacent plate-shaped members the value within the range of 1-1000 mm.   5. The method for producing a light diffusing film according to claim 3, wherein a length in the vertical direction of the plate-like member is set to a value within a range of 10 to 1000 mm.   The thickness of the said plate-shaped member shall be the value within the range of 0.1-5 mm, The manufacturing method of the light-diffusion film as described in any one of Claims 3-5 characterized by the above-mentioned.   The distance between the lower end of the incident angle width adjusting member and the surface of the coating layer is set to a value within a range of 0.1 to 1000 mm. The manufacturing method of the light-diffusion film of description.   8. The distance between the upper end of the incident angle width adjusting member and the lower end of the linear light source is set to a value within a range of 0.1 to 1000 mm. The manufacturing method of the light-diffusion film of description.   A light diffusing film characterized in that incident light is diffused in an elliptical shape with respect to a plane parallel to the light diffusing film. In the elliptical light diffusion, when the opening angle of the diffused light in the major axis direction is θ2 (°) and the opening angle of the diffused light in the minor axis direction is θ2 ′ (°), the following relational expression (1) is satisfied. The light diffusing film according to claim 9.
0.2 ≦ θ2 ′ / θ2 ≦ 0.9 (1) The light-diffusion film of Claim 9 or 10 obtained by the manufacturing method containing following process (a)-(c).
(A) Step of preparing a composition for light diffusion film (b) Step of applying the composition for light diffusion film to a step sheet and forming a coating layer (c) Active energy rays for the coating layer Irradiating
On the surface of the coating layer, at an arbitrary point located on a region where the illuminance of the active energy ray from the active energy ray light source is maximum, an azimuth angle direction in which the incident angle width of the active energy ray takes a minimum value; The azimuth angle direction in which the incident angle width of the active energy ray takes a maximum value is orthogonal, and
While the minimum value of the incident angle width of the active energy ray is a value of 10 ° or less,
The maximum value of the incident angle width of the active energy ray is set to a value in the range of more than 10 ° and 40 ° or less.