JP2012141593A - Light diffusion film and manufacturing method for light diffusion film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light diffusion film that has an excellent incident angle dependency in transmission and diffusion of light and has a wide light diffusion incident angle region, and provide a manufacturing method therefor.SOLUTION: A light diffusion film comprises: a first structure region for anisotropically diffusing an incident light; and a second structure region for isotropically diffusing the incident light. The first structure region has a louver structure that is formed by alternately arranging multiple plate regions, which differ in refractive index, in parallel along a film surface, and the second structure region has a columnar structure that is formed by arranging a grove of multiple columnar objects, which differ from a medium object in refractive index, in the medium object.

Description

  The present invention relates to a light diffusion film and a method for producing the light diffusion film. In particular, by including a louver structure region for anisotropic diffusion of incident light and a column structure region for isotropic diffusion of incident light, good incident angle dependency in light transmission and diffusion is achieved. And a light diffusion film having a wide light diffusion incident angle region and a method for producing the light diffusion film.

Conventionally, in a liquid crystal display device, it is possible to recognize a predetermined image using light emitted from a light source (internal light source) provided inside the device.
However, in recent years, with the widespread use of mobile phones, in-vehicle TVs, etc., the opportunity to view the liquid crystal display screen outside has increased, and accordingly, the light intensity from the internal light source has been defeated by external light, and the predetermined screen has been visually recognized. The problem that it becomes difficult to do arises.
In mobile applications such as mobile phones, the power consumption of the internal light source of the liquid crystal display device accounts for a large proportion of the total power consumption. The problem has arisen.

Therefore, in order to solve these problems, a reflection type liquid crystal display device using external light as part of a light source has been developed.
Such a reflective liquid crystal display device uses external light as part of the light source, so that the stronger the external light, the clearer the image can be recognized and the more effective the power consumption of the internal light source. Can be suppressed.

Further, in such a reflection type liquid crystal display device, the external light is efficiently transmitted and taken into the liquid crystal display device, and the external light is effectively used as a part of the light source. Providing a light diffusion film for diffusing has been proposed (see, for example, Patent Document 1).
More specifically, Patent Document 1 discloses a liquid crystal cell in which a liquid crystal layer 1105 is sandwiched between an upper substrate 1103 and a lower substrate 1107, as shown in FIGS. A liquid crystal device 1112 having a light reflection plate 1110 provided on the substrate 1107 side and a light control plate (light diffusion film) 1108 provided between the liquid crystal layer 1105 and the light reflection plate 1110 is disclosed. .
A light control plate 1108 is provided to selectively scatter light incident at a predetermined angle and transmit light incident at an angle other than the predetermined angle. The light control plate 1108 is incident at a predetermined angle. The scattering axis direction 1121 obtained by projecting the direction of selectively scattering light onto the surface of the light control plate 1108 is arranged in the liquid crystal cell so as to be in the direction of about 6 o'clock on the inner surface of the liquid crystal cell.

Here, as a light diffusing film used for a reflective liquid crystal display device, a specific light-curable composition is irradiated with active energy rays using a linear light source, thereby being highly refracted in the film surface direction. A light diffusion film is disclosed in which a plate-like region having a refractive index and plate-like regions having a low refractive index are alternately arranged in parallel to form a louver structure region in the film (see, for example, Patent Documents 2 to 3). ).
That is, Patent Document 2 discloses a film-shaped composition containing a plurality of compounds having a polymerizable carbon-carbon double bond, which is obtained by irradiating ultraviolet rays from a specific direction and curing the composition. In the light control film (light diffusion film) that selectively scatters only the incident light, at least one compound contained in the composition comprises a plurality of aromatic rings and one polymerizable carbon-carbon double bond. An optical control film characterized by being a compound contained in a molecule is disclosed.

  Patent Document 3 discloses a fluorene compound (A) having a polymerizable carbon-carbon double bond in the molecule, a cationic polymerizable compound (B) having a refractive index different from that of the fluorene compound (A), and A photocurable composition containing a photocationic polymerization initiator (C) and a light control film formed by curing the photocurable composition are disclosed.

On the other hand, as another type of light diffusing film used for a reflective liquid crystal device, a film of film is formed by irradiating a specific photocurable composition with active energy rays as parallel light over the entire surface. A light diffusion film formed by forming a column structure region in which a plurality of columnar objects having different refractive indexes from the medium is formed in the medium along the thickness direction is disclosed (for example, Patent Documents 4 to 4). 6).
That is, in Patent Document 4, a composition containing a photocurable compound is provided in a sheet form, 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 diffusion medium (light diffusion film) manufacturing method for forming an aggregate of a plurality of rod-shaped hardened regions extending in a cylindrical shape arranged in parallel to the direction P between a linear light source and a sheet There is disclosed a method of manufacturing a diffusion medium, characterized in that a collection of objects is interposed and light irradiation is performed through the cylindrical object.

  Further, in Cited Document 5, a linear light source is disposed so as to be spaced apart 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 is disclosed in which one side facing the composition film is provided in the same direction as the moving direction.

  Furthermore, in Patent Document 6, the shelf surface facing upward is the light absorption surface, and the inclined surface facing downward is disposed to cover the Fresnel surface of the linear Fresnel member having a reflection surface, which is larger than a predetermined angle. A diffusion layer (diffusion film) having a diffusion characteristic that does not diffuse incident light, and the diffusion layer includes a photomask having a light passage region and a light non-pass region from a predetermined direction on the photocurable resin composition. The first light irradiation step of irradiating the parallel light through the first light irradiation step for curing the irradiated portion into an incompletely cured state, and removing the photomask, and further, the parallel light with a substantially constant light intensity distribution is photocurable. A second light irradiation step of irradiating the composition to complete the curing of the photocurable composition, a matrix of the photocurable composition in the film, and parallel light in the matrix Extending in the direction of irradiation Uni reflective projection screen, characterized in that oriented the matrix and the refractive index has a phase separation structure comprising a plurality of different and columnar structures, is disclosed.

Japanese Patent No. 3480260 (claims, drawings, etc.) JP 2006-350290 A (Claims, drawings, etc.) JP 2008-239757 A (Claims, drawings, etc.) Japanese Patent No. 4095573 (claims, drawings, etc.) JP 2009-173018 A (Claims, drawings, etc.) JP 2008-256930 A (Claims, drawings, etc.)

  However, the light diffusion film having the louver structure region disclosed in Patent Documents 1 to 3 has a narrow incident angle region of incident light that can be diffused (hereinafter sometimes referred to as a light diffusion incident angle region). Furthermore, the spread angle of the diffused light was sometimes narrowed.

  In addition, the light diffusion film having the column structure region disclosed in Patent Documents 4 to 5 is more likely to cause uneven reflection of light in the film than the light diffusion film having the louver structure region. There was a problem that it was difficult to exhibit good dependence on the incident angle due to a large variation in diffusion characteristics depending on the incident angle.

In view of the above circumstances, the present inventors have made extensive efforts, and in the film, the louver structure region for anisotropically diffusing incident light, and the isotropic diffusion of incident light. The present inventors have found that a light diffusion film having a good incident angle dependency and a wide light diffusion incident angle region can be obtained by providing the column structure region.
That is, an object of the present invention is to provide a light diffusion film having a good incident angle dependency in light transmission and diffusion and having a wide light diffusion incident angle region, and a method for producing the same.

According to the present invention, there is provided a light diffusing film having a first structure region for anisotropically diffusing incident light and a second structure region for isotropically diffusing incident light. Is a louver structure region in which a plurality of plate-like regions having different refractive indexes are alternately arranged in parallel along the film surface direction, and the second structure region is the medium object in the medium object. There is provided a light diffusion film characterized in that it is a column structure region in which a plurality of pillars having different refractive indexes are forested, and the above-described problems can be solved.
That is, in the light diffusing film of the present invention, a louver structure region as a first structure region for anisotropically diffusing incident light in the film, and a second for diffusing incident light isotropically. And a column structure region as a structure region.
Therefore, by overlapping the incident angle dependency of each structural region, it is possible not only to suppress the dispersion of diffusion characteristics and obtain a good incident angle dependency, but also to effectively spread the diffused light. Can be spread.
Further, by making the incident angle dependency of each structural region different, the light diffusion incident angle region can be effectively and easily expanded.
In the present invention, the “film surface direction” means the xy plane direction when the film thickness direction is the z-axis.
In the present invention, “light diffusion incident angle region” means incident light corresponding to emitting diffused light when the angle of incident light from a point light source is changed with respect to the anisotropic light diffusing film. Means the angle range. Details of the light diffusion incident angle region will be described later.
In addition, “good incident angle dependency” is a distinction between an incident angle region (light diffusion incident angle region) with respect to a film where light diffusion of incident light occurs and other incident angle regions where light diffusion does not occur. Means that it is clearly controlled.
Furthermore, “anisotropy” in the present invention means that the shape of spread of diffused light has anisotropy, and “isotropic” means that the shape of spread of diffused light has isotropic properties. This also means that details will be described later.

Further, in configuring the light diffusion film of the present invention, the width of the plate-like regions having different refractive indexes in the first structural region is set to a value within the range of 0.1 to 15 μm, respectively, and the plate-like region Are preferably arranged in parallel at a constant inclination angle with respect to the film thickness direction.
By configuring in this way, incident light is more stably reflected in the louver structure region as the first structure region, and the incident angle dependency derived from the first structure region and the opening angle of the diffused light are reduced. Further improvement can be achieved.

In constituting the light diffusion film of the present invention, in the first structural region, the main component of the plate-like region having a high refractive index among the plate-like regions having different refractive indexes contains a plurality of aromatic rings ( It is a polymer of a meth) acrylate ester, and the main component of the plate-like region having a low refractive index is preferably a polymer of urethane (meth) acrylate.
With this configuration, not only can the louver structure as the first structural region be efficiently formed, but also the incident angle dependency and the opening angle of the diffused light derived from the first structural region are further improved. Can be made.

Moreover, in constructing the light diffusion film of the present invention, it is preferable to set the thickness of the first structural region to a value within the range of 5 to 495 μm.
With this configuration, the length of the louver structure along the film thickness direction is stably secured, and incident light is more stably reflected in the louver structure region as the first structure region. It is possible to further improve the incident angle dependency and the opening angle of the diffused light derived from the one structural region.

In constructing the light diffusing film of the present invention, in the second structural region, the maximum diameter in the cross section of the columnar object is set to a value within the range of 0.1 to 15 μm, and the distance between the columnar objects is set to 0.1. It is preferable that the value is in the range of 1 to 15 μm, and the plurality of columnar objects are forested at a constant inclination angle with respect to the film thickness direction.
By configuring in this way, incident light is more stably reflected in the column structure region as the second structure region, and the incident angle dependency derived from the second structure region and the opening angle of the diffused light are reduced. Further improvement can be achieved.

In constituting the light diffusing film of the present invention, in the second structural region, the main component of the columnar material is a polymer of (meth) acrylic acid ester containing a plurality of aromatic rings, The component is preferably a urethane (meth) acrylate polymer.
With this configuration, not only can the column structure as the second structural region be efficiently formed, but also the incident angle dependency and the opening angle of the diffused light derived from the second structural region are further improved. Can be made.

Moreover, in constructing the light diffusion film of the present invention, it is preferable to set the thickness of the second structural region to a value within the range of 5 to 495 μm.
With this configuration, the length of the columnar object along the film thickness direction is stably secured, and incident light is more stably reflected in the column structure region as the second structure region. It is possible to further improve the incident angle dependency and the opening angle of the diffused light derived from the two structural regions.

Another aspect of the present invention provides a light diffusing film having a first structural region for anisotropically diffusing incident light and a second structural region for isotropically diffusing incident light. It is a method, Comprising: It is a manufacturing method of the light-diffusion film characterized by including the following process (a)-(d).
(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) First active energy for the coating layer Irradiate with a line to form a louver structure region in which a plurality of plate-like regions having different refractive indexes as the first structure region are alternately arranged in parallel along the film surface direction in the lower part of the coating layer Step (d) of leaving a louver structure non-formed region in the upper part of the layer (d) A second active energy ray irradiation is further performed on the coating layer, and the louver structure non-formed region is placed in the medium as the second structural region. A step of forming a columnar structure region in which a plurality of pillars having a refractive index different from that of the medium is formed. That is, in the method for producing a light diffusing film of the present invention, the first active energy ray irradiation causes the first 1's After the louver structure region is formed as the structure region, the column structure region is formed as the second structure region in the unformed region existing above the first structure region by irradiating the second active energy ray. can do.
Therefore, a light diffusing film comprising a louver structure region as a first structure region and a column structure region as a second structure region in a single film in the up and down direction sequentially along the film thickness direction. Can be manufactured efficiently and stably.

Moreover, when implementing the manufacturing method of the light-diffusion film of this invention, it is preferable to irradiate the parallel light whose parallelism is a value of 10 degrees or less as 2nd active energy ray irradiation.
By carrying out in this way, a column structure region as a second structure region in which a plurality of columnar objects are formed at a constant inclination angle with respect to the film thickness direction is efficiently and stably manufactured. be able to.

FIGS. 1A to 1B are diagrams provided to explain the outline of the louver structure in the first structure region. FIGS. 2A and 2B are diagrams for explaining incident light angle dependency and anisotropy in the louver structure. FIGS. 3A to 3B are other diagrams provided for explaining the incident angle dependency in the louver structure. FIGS. 4A to 4C are diagrams for explaining the incident angle and the opening angle of the diffused light. FIGS. 5A and 5B are views provided to explain the outline of the column structure in the second structure region. FIGS. 6A and 6B are diagrams for explaining the incident angle dependency and isotropy in the column structure. FIGS. 7A to 7B are diagrams provided to explain the outline of the light diffusion film of the present invention. FIG. 8A to FIG. 8C are diagrams provided for explaining the mode of the louver structure in the first structure region. FIG. 9A to FIG. 9D are diagrams provided for explaining the mode of the column structure in the second structure region. FIG. 10 is a diagram for explaining an application example of the light diffusion film of the present invention in a reflective liquid crystal display device. FIGS. 11A and 11B are diagrams provided to explain the first active energy ray irradiation step. FIGS. 12A to 12B are other diagrams provided for explaining the first active energy ray irradiation step. FIGS. 13A to 13C are diagrams provided to explain the second active energy ray irradiation step. FIGS. 14A to 14K are diagrams provided to explain the spread of diffused light and the distribution of lightness in the light diffusing film of Example 1. FIG. FIGS. 15A to 15B are photographs provided to explain the state of the cross section of the light diffusion film of Example 1. FIG. FIG. 16 is a diagram for explaining the light diffusion film of Example 2. FIGS. 17A to 17H are diagrams provided to explain the spread of diffused light and the distribution of lightness in the light diffusing film of Example 3. FIG. 18 (a) to 18 (g) are diagrams provided to explain the spread of diffused light and the distribution of lightness in the light diffusing film of Example 4. FIG. FIGS. 19A to 19J are diagrams provided to explain the spread of diffused light and the distribution of lightness in the light diffusing film of Comparative Example 1. FIG. FIGS. 20A to 20K are diagrams provided to explain the spread of diffused light and the distribution of lightness in the light diffusing film of Comparative Example 2. FIG. FIGS. 21A to 21H are diagrams provided to explain the spread of diffused light and the distribution of lightness in the light diffusing film of Comparative Example 3. FIG. FIGS. 22A to 22I are diagrams provided to explain the spread of diffused light and the distribution of lightness in the light diffusing film of Comparative Example 4. FIG. FIGS. 23A and 23B are views for explaining a reflection type liquid crystal device using a conventional light diffusion film.

[First Embodiment]
The first embodiment of the present invention is a light diffusion film having a first structure region for anisotropically diffusing incident light and a second structure region for isotropically diffusing incident light. The first structure region is a louver structure region in which a plurality of plate-like regions having different refractive indexes are alternately arranged in parallel along the film surface direction, and the second structure region is included in the medium object. The medium is a light diffusing film characterized in that it is a column structure region in which a plurality of pillars having different refractive indexes are planted.
Hereinafter, the light diffusion film according to the first embodiment of the present invention will be specifically described with reference to the drawings as appropriate.

1. Basic Principle Hereinafter, the basic principles of light diffusion by the louver structure and light diffusion by the column structure in the light diffusion film will be described.

(1) Light diffusion by louver structure FIG. 1A shows a top view (plan view) of a first structure region 10 having only a louver structure region and anisotropically diffusing incident light. 1B, the first structure region 10 shown in FIG. 1A is cut along the dotted line AA in the vertical direction, and the cut surface is viewed from the arrow direction. A cross-sectional view of one structural region 10 is shown.
In the present invention, as shown in FIGS. 2A to 2B, anisotropy means that when 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) has different properties depending on the direction in the same plane.
More specifically, in the case of the first structural region 10, the diffused emitted light is mainly in a direction perpendicular to the direction of the louver structure extending along the film surface direction in a plane parallel to the film. Since the light is diffused to the surface, the shape of the spread of the diffused light becomes substantially elliptical.

Further, as shown in the plan view of FIG. 1A, the first structural region 10 has a plate-like region 12 having a relatively high refractive index and a plate-like region 14 having a relatively low refractive index in the film surface direction. , And a louver structure 13 that extends while being alternately arranged in parallel.
In addition, 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. Even in the vertical direction of one structural region 10, the state of being alternately arranged in parallel is maintained.
As a result, as shown in FIGS. 2A to 2B, it is estimated that the incident light is diffused by the first structural region 10 when the incident angle is within the light diffusion incident angle region. The
That is, as shown in FIG. 1B, the incident angle of the incident light with respect to the first structure region 10 is a value within a predetermined angle range from parallel to the boundary surface 13 ′ of the louver structure 13, that is, light. When the value is within the diffuse incident angle region, the incident light (52, 54) passes through the high refractive index plate-like region 12 in the louver structure along the film thickness direction while changing the direction. Thus, it is estimated that the traveling direction of light on the light exit surface side is not uniform.
As a result, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused by the first structure region 10 (52 ′, 54 ′).

In addition, as shown to FIG. 2 (a)-(b), FIG. 6 (a)-(b), and FIG. 7 (a)-(b), the light-diffusion incident angle area | region has a louver structure in a light-diffusion film, The angle region is determined for each light diffusion film depending on the difference in refractive index of the column structure, the inclination angle, and the like.
In addition, the direction change of the incident light in the high refractive index plate-like region 12 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, a gradient index type in which the direction changes in a curved shape may be considered.
On the other hand, when the incident angle of the incident light with respect to the first structure region 10 deviates from the light diffusion incident angle region, the incident light 56 is not diffused by the first structure region 10 and remains as it is in the first structure. It is presumed to pass through region 10 (56 ').

With the above mechanism, the first structural region 10 including the louver structure 13 can exhibit incident angle dependence in light transmission and diffusion as shown in FIGS. 2 (a) to 2 (b), for example. It becomes possible.
Further, as shown in FIGS. 2A to 2B, the first structural region is a case where the incident angle is different when the incident angle of the incident light is included in the light diffusion incident angle region. However, substantially the same light diffusion can be performed on the light exit surface side.
Therefore, it can be said that the first structure region also has a light collecting function for concentrating light at a predetermined location. This light condensing effect is also the same effect in the second structural region described later and the light diffusion film of the present invention.

Here, the relationship between the incident angle of the incident light with respect to the first structure region and the opening angle of the diffused light diffused by the first structure region will be described with reference to FIG.
That is, in FIG. 3A, the horizontal axis represents the incident angle (°) of incident light with respect to the first structural region, and the vertical axis represents the opening angle (°) of diffused light diffused by the first structural region. A characteristic curve is shown.
Also, as shown in FIGS. 4A to 4C, the incident angle θ1 means an angle (°) when the angle of incidence perpendicular to the first structure region 10 is 0 °. .
More specifically, as described above, the incident light component contributing to the anisotropic light diffusion is a component perpendicular to the direction of the louver structure extending mainly in the film surface direction. The term “incident angle θ1” means the incident angle of a component perpendicular to the direction of the louver structure extending in the film surface direction. 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 °.
Further, the spread light opening angle θ2 literally means the spread light opening angle (°).
The larger the opening angle of the diffused light, the more effectively the light incident at the incident angle at that time is effectively diffused by the first structural region.
Conversely, the smaller the opening angle of the diffused light, the light incident at the incident angle at that time is transmitted through the first structure region as it is and does not diffuse.
A specific method for measuring the opening angle of the diffused light will be described in Examples.

That is, as understood from the characteristic curve shown in FIG. 3A, in the first structure region, the degree of light transmission and diffusion varies greatly depending on the difference in the incident angle, and the light diffusion incident angle region and , And other incident angle regions can be clearly separated.
On the other hand, in the case of a film having no incident angle dependency, as shown in FIG. 3B, the change in the incident angle does not have a clear influence on the degree of light transmission and diffusion, and light diffusion. The incident angle region cannot be identified.

(2) Light Diffusion by Column Structure FIG. 5A is a top view (plan view) of the second structure region 20 that has only the column structure region and isotropically diffuses incident light. FIG. 5B shows a case where the second structural region 20 shown in FIG. 5A is cut in the vertical direction along the dotted line AA, and the cut surface is viewed from the arrow direction. A cross-sectional view of the second structural region 20 is shown.
In the present invention, isotropic means that, as shown in FIGS. 6A to 6B, when light is diffused by a film, the diffused emitted light is in a plane parallel to the film. It 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, in the case of the second structure region 20, the diffusion degree of the diffused emitted light is circular in a plane parallel to the film.

Here, as shown in the plan view of FIG. 5A, the second structural region 20 has a column structure (column structure (column 22) having a columnar object 22 having a relatively high refractive index and a medium object 24 having a relatively low refractive index. 22 and 24).
Further, as shown in the cross-sectional view of FIG. 5B, in the vertical direction of the second structure region 20, the columnar object 22 having a relatively high refractive index and the medium object 24 having a relatively low refractive index are respectively They have a predetermined width and are arranged alternately.
Accordingly, as shown in FIGS. 6A to 6B, it is estimated that the incident light is diffused by the second structure region 20 when the incident angle is within the light diffusion incident angle region. The
That is, as shown in FIG. 5B, the incident angle of the incident light with respect to the second structure region 20 is a value within a predetermined angle range from parallel to the boundary surface 23 ′ of the column structure 23, that is, light. When the value is within the diffusion incident angle region, incident light (62, 64) passes through the high refractive index columnar body 22 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 angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused by the second structure region 20 (62 ′, 64 ′).

In addition, the change in the direction of incident light in the columnar object 22 having a high refractive index in the column structure is a step index type in which the direction changes linearly and zigzag by total reflection as shown in FIG. A gradient index type that changes its direction in a curved shape is also conceivable.
On the other hand, when the incident angle of the incident light with respect to the second structure region 20 deviates from the light diffusion incident angle region, the incident light 66 is not diffused by the second structure region 20 and remains as it is in the second structure region. It is presumed to pass through region 20 (66 ').

With the above mechanism, the second structural region 20 including the column structure 23 can exhibit incident angle dependency in light transmission and diffusion as shown in FIGS. 6A to 6B, for example. It becomes possible.
Note that the relationship between the incident angle of the incident light with respect to the second structural region and the opening angle of the diffused light diffused by the second structural region is the same as that in the above-described first structural region. The description of is omitted.

2. Basic Configuration Next, the basic configuration of the light diffusion film of the present invention will be described with reference to the drawings.
As shown in FIGS. 7A to 7B, the light diffusion film 30 of the present invention has a louver structure region (first structure region) 10 for anisotropically diffusing incident light, incident light and the like. And a column structure region (second structure region) 20 for anisotropic diffusion. Preferably, these structure regions are sequentially included in the vertical direction along the film thickness direction. .
Therefore, with the light diffusion film of the present invention, for example, as shown in FIG. 7A, the dispersion of the diffusion characteristics is suppressed by overlapping the incident angle dependency of the first and second structural regions. In addition, not only good incident angle dependency can be obtained, but also the opening angle of diffused light can be effectively widened.
Moreover, if it is the light-diffusion film of this invention, as shown in FIG.7 (b), the light-diffusion incident-angle area | region is effective by shifting the incident-angle dependence which the 1st and 2nd structure area | region has, for example. Can be spread easily and easily.

3. 1st structure area The light-diffusion film of this invention is a board | plate with a relatively high refractive index as a 1st structure area | region for anisotropically diffusing incident light, ie, several plate-shaped area | regions from which refractive index differs. The plate-like region (high refractive index portion) and the plate-like region (low refractive index portion) having a relatively low refractive index have louver structure regions that are alternately arranged in parallel along the film surface direction. .
Hereinafter, the first structure region will be specifically described.

(1) Refractive index Further, in the first structural region, the difference in refractive index between the plate-like regions having different refractive indexes, that is, the difference between the refractive index of the high refractive index portion and the refractive index of the low refractive index portion. A value of 0.01 or more is preferable.
This is because the incident light is stably reflected in the louver structure region as the first structure region by setting the difference in refractive index to a value of 0.01 or more, and is derived from the first structure region. This is because the incident angle dependency and the opening angle of the diffused light can be further improved.
More specifically, when the difference in refractive index is a value less than 0.01, the angle range in which incident light is totally reflected in the louver structure is narrowed, so that the incident angle dependency is excessively reduced, This is because the opening angle of the diffused light may become excessively narrow.
Accordingly, the difference in refractive index between the plate-like regions having different refractive indexes in the first structure region is more preferably 0.05 or more, and further preferably 0.1 or more.
Note that the larger the difference between the refractive index of the high refractive index portion and the refractive index of the low refractive index portion, the better. However, from the viewpoint of selecting a material capable of forming a louver structure, about 0.3 is considered the upper limit. It is done.

In the first structure region, the refractive index of the plate-like region (high refractive index portion) having a relatively high refractive index is preferably set to a value in the range of 1.5 to 1.7.
This is because if the refractive index of the high refractive index portion is less than 1.5, the difference from the low refractive index portion becomes too small and it may be difficult to obtain a desired louver structure. is there.
On the other hand, when the refractive index of the high refractive index portion exceeds 1.7, the compatibility between the material substances in the light diffusion film composition may be excessively lowered.
Therefore, it is more preferable to set the refractive index of the high refractive index portion in the first structure region to a value in the range of 1.52 to 1.65, and to a value in the range of 1.55 to 1.6. Is more preferable.
The refractive index of the high refractive index portion can be measured according to JIS K0062.

In the first structure region, it is preferable to set the refractive index of the plate-like region (low refractive index portion) having a relatively low refractive index to a value within the range of 1.4 to 1.5.
The reason for this is that if the refractive index of the low refractive index portion is less than 1.4, the rigidity of the obtained light diffusion film may be lowered.
On the other hand, when the refractive index of the low refractive index portion exceeds 1.5, the difference from the refractive index of the high refractive index portion becomes too small, and it may be difficult to obtain a desired louver structure. Because there is.
Therefore, it is more preferable to set the refractive index of the low refractive index portion in the first structure region to a value in the range of 1.42 to 1.48, and to a value in the range of 1.44 to 1.46. Is more preferable.
In addition, the refractive index in a low refractive index part can be measured according to JIS K0062, for example.

(2) Width As shown in FIGS. 8A to 8B, the widths (S1, S2) of the high refractive index portion 12 and the low refractive index portion 14 having different refractive indexes in the first structural region are set. These values are each preferably in the range of 0.1 to 15 μm.
This is because the incident light is more stably reflected in the louver structure region as the first structure region by setting the width of these plate-like regions to a value in the range of 0.1 to 15 μm. This is because the incident angle dependency derived from the first structure region and the opening angle of the diffused light can be further improved.
That is, if the width of the plate-like region is less than 0.1 μm, it may be difficult to exhibit light diffusibility regardless of the incident angle of incident light. On the other hand, when the width exceeds 15 μm, the light traveling straight in the louver structure increases, and the uniformity of light diffusion may deteriorate.
Therefore, in the first structure region, the width of the plate-like regions having different refractive indexes is more preferably set to a value within the range of 0.5 to 10 μm, and the value within the range of 1 to 5 μm. Further preferred.
In addition, the width | variety, length, etc. of the plate-shaped area | region which comprises a louver are computable by observing with an optical digital microscope.

(3) Length In addition, as shown in FIGS. 8A to 8B, in the first structure region, the lengths L1 of the high refractive index portion 12 and the low refractive index portion 14 having different refractive indexes are set respectively. A value in the range of 5 to 495 μm is preferable.
The reason for this is that when the length is less than 5 μm, the length of the louver structure is insufficient, and the incident light that goes straight through the louver structure increases. This is because it may be difficult to obtain the angle.
On the other hand, when the length exceeds 495 μm, when the louver structure is formed by irradiating the composition for light diffusing film with active energy rays, the photopolymerization progresses by the louver structure formed initially. This is because the direction may diffuse and it may be difficult to form a desired louver structure.
Therefore, in the first structure region, the lengths of the plate-like regions having different refractive indexes are more preferably values in the range of 40 to 310 μm, and values in the range of 95 to 255 μm. Further preferred.
In addition, as shown in FIG.8 (b), the louver structure does not need to be formed to the upper-lower-end part in a film thickness direction in a 1st structure area | region.
In this case, the width L2 of the upper and lower end portions where the louver structure is not formed is preferably a value in the range of 0 to 100 μm, although it depends on the thickness of the first structure region, and is preferably in the range of 0 to 50 μm. It is more preferable that the value is within the range of 0 to 5 μm.

(4) Inclination angle Moreover, as shown to Fig.8 (a)-(b), in the 1st structure area, the high refractive index part 12 and the low refractive index part 14 from which a refractive index differs differ with respect to a film thickness direction. And extending at a constant inclination angle θa.
The reason for this is that by making the inclination angle of the plate-like region constant, the incident light is more stably reflected in the louver structure region as the first structure region, and the incident angle derived from the first structure region. This is because the dependency and the opening angle of the diffused light can be further improved.
Moreover, as shown in FIG.8 (c), it is also preferable that the louver structure is bent.
This is because the louver structure is bent, so that the incident light that goes straight through the louver structure can be reduced and the uniformity of light diffusion can be improved.

Note that such a bent louver structure can be obtained by irradiating light while changing the irradiation angle of irradiation light when performing the first active energy ray irradiation described in the second embodiment. However, it greatly depends on the type of material that forms the louver structure.
Θa is the inclination of the plate-like region when the angle with respect to the normal of the film surface measured in a cross section when the film is cut in a plane perpendicular to the louver structure extending along the film surface direction is 0 ° It means an angle (°).
More specifically, as shown in FIG. 8, the angle on the narrow side among the angles formed by the normal of the film surface on the incident light irradiation side and the plate-like region is meant. As shown in FIG. 8A, the inclination angle when the louver is inclined to the right is used as a reference, and the inclination angle when the louver is inclined to the left is expressed as minus.

(5) Thickness Moreover, it is preferable that the thickness of the first structural region is set to a value within a range of 5 to 495 μm.
This is because, by setting the thickness of the first structural region to a value within this range, the length of the louver structure along the film thickness direction can be stably secured, and the louver as the first structural region This is because incident light can be more stably reflected in the structure region, and the incident angle dependency and the opening angle of the diffused light derived from the first structure region can be further improved.
That is, when the thickness of the first structure region is less than 5 μm, the length of the louver structure is insufficient, and the incident light that goes straight through the louver structure increases. This is because it may be difficult to obtain the opening angle of the diffused light.
On the other hand, when the thickness of the first structural region exceeds 495 μm, when the louver structure is formed by irradiating the composition for light diffusion film with active energy rays, the louver formed at the initial stage is formed. This is because the traveling direction of photopolymerization is diffused depending on the structure, and it may be difficult to form a desired louver structure.
Therefore, the thickness of the first structure region is more preferably set to a value within the range of 40 to 310 μm, and further preferably set to a value within the range of 95 to 255 μm.

(6) Material substance (6) -1 High refractive index portion In the first structure region, a high refractive index portion that is a plate-like region having a relatively high refractive index among plate-like regions having different refractive indexes. Although the kind of material substance for constituting is not particularly limited, it is preferable that the main component is a (meth) acrylic acid ester polymer containing a plurality of aromatic rings.
This is because, with such a material substance, not only can the louver structure as the first structural region be efficiently formed, but also the incident angle dependency and the opening angle of the diffused light derived from the first structural region. This is because the can be further improved.
That is, when the first structural region is formed by using a polymer of a specific (meth) acrylic acid ester as the main component of the high refractive index portion (hereinafter sometimes referred to as the (A1) component). , The polymerization rate of the monomer component (hereinafter sometimes referred to as the monomer (A1) component) that becomes the component (A1) by polymerization is determined based on the main component (hereinafter, ( It is presumed that the polymerization rate of the monomer component (hereinafter sometimes referred to as the monomer (B1) component) that becomes the B1) component) can be made faster.
Then, a predetermined difference is caused in the polymerization rate between these monomer components, and both monomer components are prevented from being uniformly copolymerized. More specifically, the compatibility of both monomer components is kept within a predetermined range. It is presumed that the copolymerizability between the two monomer components can be effectively reduced by lowering.
As a result, a louver structure in which the component (A1) and the component (B1) extend alternately along the film in-plane direction can be efficiently formed by irradiation with active energy rays.
Further, by using a specific (meth) acrylic acid ester as the monomer (A1) component, the compatibility with the monomer (B1) component is reduced to a predetermined range, and the louver structure is formed more efficiently. Can do.
Further, by including a specific (meth) acrylic acid ester polymer as the component (A1), the refractive index of the plate-like region derived from the component (A1) in the louver structure is increased, and the component (B1) The difference from the refractive index of the derived plate-like region can be adjusted to a value greater than or equal to a predetermined value.
Accordingly, by including a specific (meth) acrylic acid ester polymer as the component (A1), combined with the characteristics of the component (B1) described later, cured products having different refractive indexes are alternately arranged along the in-plane direction of the film. A louver structure extending in the above can be efficiently obtained.
Therefore, it is possible to obtain a first structure region having a good incident angle dependency in light transmission and diffusion and a wide light diffusion incident angle region.
The “(meth) acrylic acid ester containing a plurality of aromatic rings” means a compound having a plurality of aromatic rings in the ester portion of the (meth) acrylic acid ester.
“(Meth) acrylic acid” means both acrylic acid and methacrylic acid.

  In addition, examples of the (meth) acrylic acid ester containing a plurality of aromatic rings as the monomer (A1) component constituting the component (A1) include, for example, biphenyl (meth) acrylate and naphthyl (meth) acrylate. , Anthracyl (meth) acrylate, Benzylphenyl (meth) acrylate, Biphenyloxyalkyl (meth) acrylate, Naphtyloxyalkyl (meth) acrylate, Anthracyloxyalkyl (meth) acrylate, Benzyl (meth) acrylate Examples thereof include phenyloxyalkyl and the like, or those partially substituted with halogen, alkyl, alkoxy, alkyl halide, and the like.

  The (meth) acrylic acid ester containing a plurality of aromatic rings as the monomer (A1) component constituting the component (A1) preferably includes a compound containing a biphenyl ring. In particular, the following general formula (1 It is preferable that the biphenyl compound represented by this is included.

(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 using a biphenyl compound having a specific structure as the monomer (A1) component constituting the (A1) component, the polymerization rate of the monomer (A1) component is made higher than the polymerization rate of the monomer (B1) component. This is because it is estimated that it can be made even faster.
In addition, it is estimated that the compatibility with the monomer (B1) component can be more easily lowered to a predetermined range, and the refractive index of the plate-like region derived from the (A1) component in the louver structure is increased. And the difference with the refractive index of the plate-shaped area | region originating in the (B1) component can be adjusted more easily to the value more than predetermined.
Furthermore, it is liquid at the monomer stage before photocuring and can be uniformly mixed with urethane (meth) acrylate, which is a typical example of the monomer (B1) component, without using a diluent solvent or the like.

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 monomer (A1) component decreases, or the refractive index of the plate-like region derived from the (A1) component in the louver structure becomes too low. This is because it may be difficult to efficiently form a predetermined louver structure in the first structure region.
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 dioxins are prevented from being generated when the light diffusion film is incinerated and the like, which is preferable from the viewpoint of environmental protection.
Incidentally, in an anisotropic light diffusing film having a conventional louver structure, in order to obtain a predetermined louver structure, it is general that halogen substitution is performed in 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, by using the biphenyl compound represented by the general formula (1) as the monomer (A1) component, good incident angle dependency can be exhibited even when no halogen is contained.

Moreover, it is preferable that any one of R < ² > -R < ⁹ > in General formula (1) is a substituent represented by General formula (2).
The reason for this is that the monomer (A1) components are aligned in the stage before photocuring by setting the position of the substituent represented by the general formula (2) to a position other than R ¹ and R ¹⁰ in the biphenyl ring. In addition, crystallization can be effectively prevented.
As a result, in the photocuring stage, the monomer (A1) component and the monomer (B1) component can be aggregated and phase-separated at a fine level, and the first structural region having a predetermined louver structure is more efficient. It is because it can be obtained.
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 monomer (A1) components at the polymerization site. Because there is.
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 particular, from the viewpoint of preventing the position of the polymerizable carbon-carbon double bond, which is the polymerization site, from being too close to the biphenyl ring, the biphenyl ring becoming a steric hindrance, and the polymerization rate of the monomer (A1) component being lowered. The carbon number n in the substituent represented by the general formula (2) is more preferably an integer of 2 to 4, more preferably an integer of 2 to 3.

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

Moreover, it is preferable to make the weight average molecular weight of the monomer (A1) component which comprises a (A1) component into the value within the range of 200-2,500.
This is because the monomer (A1) component and the monomer (B1) component are copolymerized by increasing the polymerization rate of the monomer (A1) component by setting the weight average molecular weight of the monomer (A1) component within a predetermined range. This is because it is estimated that the sex can be reduced more effectively.
As a result, when photocured, the louver structure in which the components (A1) and (B1) extend alternately along the film surface direction can be more efficiently formed.
That is, when the weight average molecular weight of the monomer (A1) component is less than 200, for example, the position of the plurality of aromatic rings and the position of the polymerizable carbon-carbon double bond are too close, and the polymerization rate is increased due to steric hindrance. This is because it may be lowered to be close to the polymerization rate of the monomer (B1) component, and copolymerization with the monomer (B1) component may easily occur. On the other hand, when the weight average molecular weight of the monomer (A1) component exceeds 2,500, the polymerization rate of the monomer (A1) component decreases to approach the polymerization rate of the monomer (B1) component, and the monomer (B1) This is because it may be difficult to efficiently form a louver structure as a result of the ease of copolymerization with components.
Therefore, the weight average molecular weight of the monomer (A1) component 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 weight average molecular weight of the monomer (A1) component can be measured using gel permeation chromatography (GPC), or can be calculated from the structural formula based on the atomic weight of the constituent atoms. .

Moreover, it is preferable to use a single monomer (A1) component that forms a plate-like region having a high refractive index in the louver structure.
The reason for this is that, by configuring in this way, the variation in the refractive index in the plate-like region derived from the component (A1) in the louver structure, that is, the plate-like region having a high refractive index, is effectively suppressed, and a predetermined louver is obtained. This is because the first structure region having the structure can be obtained more efficiently.
That is, when the monomer (A1) component has low compatibility with the monomer (B1) component, for example, when the monomer (A1) component is a halogen compound, the monomer (A1) component is compatible with the monomer (B1) component. As the third component for the purpose, other monomer (A1) components (for example, non-halogen compounds) may be used in combination.
However, in this case, the refractive index in the plate-like region having a high refractive index derived from the component (A1) may vary or decrease due to the influence of the third component.
As a result, the refractive index difference from the plate-like region having a low refractive index derived from the component (B1) 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 monomer (B1) component and to use it as a single monomer (A1) component.
In addition, for example, since it is compatible with the monomer (B1) component if it is a biphenyl compound represented by the formulas (3) to (4) as the monomer (A1) component, as a single monomer (A1) component Can be used.

(6) -2 Low Refractive Index Part In the first structural region, among the plate-like regions having different refractive indexes, the type of material substance for constituting the low refractive index portion that is a plate-like region having a low refractive index. Is not particularly limited, but the main component is preferably a urethane (meth) acrylate polymer.
This is because, with such a material substance, not only can the louver structure as the first structural region be efficiently formed, but also the incident angle dependency and the opening angle of the diffused light derived from the first structural region. This is because the can be further improved.
That is, by making the main component of the low refractive index part (component (B1)) a urethane (meth) acrylate polymer, the refractive index of the plate-like region derived from the component (A1) and the component derived from the component (B1) The difference between the refractive index of the plate-like region and the refractive index of the plate-like region can be adjusted more easily. This is because the structure region can be obtained more efficiently.
In addition, (meth) acrylate means both acrylate and methacrylate.

First, the urethane (meth) acrylate as the component (B1) constituting the component (B1) is composed of (a) a compound containing at least two isocyanate groups, (b) polyalkylene glycol, and (c) hydroxyalkyl. It is formed from (meth) acrylate.
Among these, as the compound containing at least two isocyanate groups as component (a), 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 Over preparative based trifunctional adduct), and the like.

Moreover, among the above-mentioned, it is preferable that it is an alicyclic polyisocyanate.
The reason for this is that the cycloaliphatic polyisocyanate is easier to provide a difference in the reaction rate of each isocyanate group than the aliphatic polyisocyanate due to the conformation, etc. This is because molecular design of acrylate becomes easy.
In particular, the component (a) is preferably an alicyclic diisocyanate.
This is because, for example, an alicyclic diisocyanate suppresses that the component (a) reacts only with the component (b) or the component (a) reacts only with the component (c). This is because the component (a) can be reliably reacted with the component (b) and the component (c), and generation of extra by-products can be prevented.
As a result, it is possible to effectively suppress variations in the refractive index in the plate-like region derived from the component (B1) in the first structure region, that is, the plate-like region having a low refractive index.

Moreover, if it is an alicyclic diisocyanate, compared with aromatic diisocyanate, the monomer (B1) component obtained and the biphenyl compound which has a specific structure which is a typical example as a monomer (A1) component, and The louver structure can be formed more efficiently by reducing the compatibility of the louver to a predetermined range.
Furthermore, if it is an alicyclic diisocyanate, since the refractive index of the monomer (B1) component obtained can be made small compared with an aromatic diisocyanate, it is a typical example of a monomer (A1) component. A difference from the refractive index of a biphenyl compound having a specific structure can be increased, and a louver structure excellent in incident angle dependency can be formed more efficiently.
Among these alicyclic diisocyanates, isophorone diisocyanate (IPDI) is particularly preferable because of the large difference in reactivity between the two isocyanate groups.

Among the components that form urethane (meth) acrylate as the monomer (B1) component, examples of the polyalkylene glycol as the component (b) include polyethylene glycol, polypropylene glycol, polybutylene glycol, and polyhexylene glycol. Among them, polypropylene glycol is particularly preferable.
This is because polypropylene glycol can be handled without a solvent because of its low viscosity.
Moreover, if it is a polypropylene glycol, when a monomer (B1) component is hardened, it will become a favorable soft segment in the said hardened | cured material, Since the handling property and mounting property of a light-diffusion film can be improved effectively. It is.
In addition, the weight average molecular weight of a monomer (B1) component can be adjusted with the weight average molecular weight of (b) component. Here, the weight average molecular weight of (b) component is 2,300-19,500 normally, Preferably it is 4,300-14,300, Especially preferably, it is 6,300-12,300.

Moreover, as a hydroxyalkyl (meth) acrylate which is (c) component among the components which form urethane (meth) acrylate as a monomer (B1) component, 2-hydroxyethyl (meth) acrylate, 2-hydroxy is mentioned, for example. Examples include propyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like.
In addition, from the viewpoint of reducing the polymerization rate of the obtained urethane (meth) acrylate and more efficiently forming a predetermined louver 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 (a)-(c) component can be implemented in accordance with a conventional method.
At this time, the blending ratio of the components (a) to (c) is preferably set to a ratio of (a) component: (b) component: (c) 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 (a) reacts with and binds to two hydroxyl groups of the component (b), and two (a) This is because the urethane (meth) acrylate in which the hydroxyl group of the component (c) reacts with and bonds to the other isocyanate group of each component can be efficiently synthesized.
Therefore, the mixing ratio of the components (a) to (c) is more preferably set to a ratio of (a) component: (b) component: (c) component = 1-3: 1: 1-3 in molar ratio. Preferably, the ratio is 2: 1: 2.

Moreover, it is preferable to make the weight average molecular weight of the monomer (B1) component which comprises (B1) component into the value within the range of 3,000-20,000.
This is because, by setting the weight average molecular weight of the monomer (B1) component within a predetermined range, a predetermined difference is caused in the polymerization rate of the monomer (A1) component and the monomer (B1) component, and the copolymerization of both components is performed. This is because it is presumed that this can be effectively reduced.
As a result, it is possible to efficiently form a louver structure in which the components (A1) and (B1) extend alternately when photocured.
That is, when the weight average molecular weight of the monomer (B1) component becomes a value less than 3,000, the polymerization rate of the monomer (B1) component increases, and the polymerization rate of the monomer (A1) component becomes close to the monomer (A1). This is because it may be difficult to efficiently form a louver structure as a result of the ease of copolymerization with components. On the other hand, when the weight average molecular weight of the monomer (B1) component exceeds 20,000, it is difficult to form a louver structure in which the (A1) component and the (B1) component alternately extend in the film surface direction. This is because the compatibility with the monomer (A1) component may be excessively lowered, and the monomer (A1) component may be precipitated at the application stage of the light diffusing film composition.
Therefore, the weight average molecular weight of the monomer (B1) component 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. .
The weight average molecular weight of the monomer (B1) component can be measured using gel permeation chromatography (GPC), or can be calculated from the structural formula based on the atomic weight of the constituent atoms. .

In addition, the monomer (B1) component may be used in combination of two or more different molecular structures and weight average molecular weights, but the viewpoint of suppressing variation in the refractive index of the plate-like region derived from the (B1) component in the louver structure. It is preferable to use only one type.
That is, when a plurality of monomer (B1) components are used, the refractive index in the plate-like region having a low refractive index derived from the (B1) component varies or increases, and the refractive index derived from the (A1) component This is because the refractive index difference from the high plate-like region may become non-uniform or excessively decrease.

4). Second Structural Region The light diffusing film of the present invention has a plurality of pillars having a refractive index different from that of the medium as a second structural region for isotropic diffusion of incident light. And a column structure region.
Hereinafter, the second structure region will be specifically described.

(1) Refractive index In the second structural region, it is preferable that the difference between the refractive index of the columnar object and the refractive index of the medium object is 0.01 or more.
This is because the incident light is stably reflected in the column structure region as the second structure region by setting the difference in refractive index to a value of 0.01 or more, and is derived from the second structure region. This is because the incident angle dependency and the opening angle of the diffused light can be further improved.
That is, when the difference in refractive index is less than 0.01, the angle range at which incident light is totally reflected in the column structure is narrowed. This is because the angle may become excessively narrow.
Therefore, the difference between the refractive index of the columnar object and the refractive index of the medium object in the second structure region is more preferably 0.05 or more, and further 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 column structure, about 0.3 is considered to be an upper limit.

(2) Maximum diameter Moreover, as shown to Fig.9 (a), it is preferable to make the maximum diameter S3 in the cross section of a columnar object into the value within the range of 0.1-15 micrometers in a 2nd structure area | region.
This is because, by setting the maximum diameter to a value in the range of 0.1 to 15 μm, incident light is more stably reflected in the column structure region as the second structure region, and the second structure This is because the incident angle dependency derived from the region and the opening angle of the diffused light can be further improved.
That is, when the maximum diameter is less than 0.1 μm, it may be difficult to exhibit light diffusibility regardless of the incident angle of incident light. On the other hand, when the maximum diameter exceeds 15 μm, the light traveling straight in the column structure increases, and the uniformity of light diffusion may deteriorate.
Therefore, in the second structure region, the maximum diameter in the cross section of the columnar object is more preferably set to a value within the range of 0.5 to 10 μm, and further preferably set to a value within the range of 1 to 5 μm.
In addition, although it does not specifically limit about the cross-sectional shape of a columnar thing, For example, it is preferable to set it as a circle, an ellipse, a polygon, an irregular shape, etc.
Moreover, the cross section of a columnar thing means the cross section cut | disconnected by the surface parallel to the film surface.
The maximum diameter and length of the columnar object can be calculated by observing with an optical digital microscope.

(3) Length In the second structure region, the length L3 of the columnar object is preferably set to a value in the range of 5 to 495 μm.
The reason for this is that when the length is less than 5 μm, the length of the columnar object is insufficient, and the incident light that goes straight through the column structure increases. This is because it may be difficult to obtain the angle.
On the other hand, when the length exceeds 495 μm, when the column structure is formed by irradiating the composition for light diffusing film with active energy rays, photopolymerization proceeds by the initially formed column structure. This is because the direction may diffuse and it may be difficult to form a desired column structure.
Therefore, in the second structure region, the length of the columnar body is more preferably set to a value within the range of 40 to 310 μm, and further preferably set to a value within the range of 95 to 255 μm.
In addition, as shown in FIG.9 (c), the column structure does not need to be formed to the upper-lower-end part in a film thickness direction in a 2nd structure area | region.
In this case, the width L4 of the upper and lower end portions where the column structure is not formed is generally a value within the range of 0 to 50 μm, although it depends on the thickness of the second structural region, and is preferably within the range of 0 to 5 μm. It is more preferable that the value be within the range.

(4) Distance between columnar objects As shown in FIG. 9A, in the second structure region, the distance between the columnar objects, that is, the space P between adjacent columnar objects is in the range of 0.1 to 15 μm. It is preferable to set the value within the range.
This is because the incident light is more stably reflected in the column structure region as the second structure region by setting the distance to a value within the range of 0.1 to 15 μm. This is because the incident angle dependency and the opening angle of the diffused light derived from the above can be further improved.
That is, if the distance is less than 0.1 μm, it may be difficult to exhibit light diffusibility regardless of the incident angle of incident light. On the other hand, when the distance exceeds 15 μm, the light traveling straight in the column structure increases, and the uniformity of light diffusion may deteriorate.
Therefore, in the second structure region, the distance between the columnar objects is more preferably set to a value within the range of 0.5 to 10 μm, and further preferably set to a value within the range of 1 to 5 μm.

(5) Inclination angle In addition, as shown in FIGS. 9B to 9C, in the second structure region, the columnar object 22 is made up of forest with a constant inclination angle θb with respect to the film thickness direction. Is preferred.
The reason for this is that by making the inclination angle of the columnar object constant, incident light is more stably reflected in the column structure region as the second structure region, and the incident angle dependence derived from the second structure region This is because the property and the opening angle of the diffused light can be further improved.
Moreover, as shown in FIG.9 (d), it is also preferable that the columnar thing is bent.
This is because the columnar object is bent, so that the incident light traveling straight in the column structure can be reduced and the uniformity of light diffusion can be improved.
Note that such a bent columnar object can be obtained by irradiating light while changing the irradiation angle of the irradiation light when performing the second active energy ray irradiation described in the second embodiment. However, it also depends greatly on the type of material that forms the column structure.
Θb is a plane perpendicular to the film surface, and is an angle with respect to the normal of the film surface measured in a cross section when the film is cut by a plane that cuts one entire columnar body into two along the axis. Means the inclination angle (°) of the columnar object when the angle is set to 0 ° (the angle on the narrow side of the angles formed by the normal and the columnar object). Note that, as shown in FIG. 9B, the tilt angle when the column is tilted to the right is used as a reference, and the tilt angle when the column is tilted to the left is expressed as minus.

(6) Thickness The thickness of the second structural region is preferably set to a value in the range of 5 to 495 μm.
This is because, by setting the thickness of the second structural region to a value within this range, the length of the columnar object along the film thickness direction can be stably secured, and the column as the second structural region can be obtained. This is because incident light can be more stably reflected in the structure region, and the incident angle dependency and the opening angle of the diffused light derived from the second structure region can be further improved.
That is, when the thickness is less than 5 μm, the length of the columnar object is insufficient, and the incident light that goes straight through the column structure increases. This is because it may be difficult to obtain. On the other hand, when the thickness exceeds 495 μm, when the column structure is formed by irradiating the composition for light diffusing film with active energy rays, photopolymerization proceeds by the initially formed column structure. This is because the direction may diffuse and it may be difficult to form a desired column structure.
Therefore, the thickness of the second structural region is more preferably set to a value within the range of 40 to 310 μm, and further preferably set to a value within the range of 95 to 255 μm.

(7) Material Substance (7) -1 Columnar Material In the second structural region, the type of material substance constituting the columnar material is not particularly limited, but the main component contains a plurality of aromatic rings (meta ) A polymer of acrylic acid ester is preferred.
This is because, with such a material substance, not only can the column structure as the second structural region be efficiently formed, but also the incident angle dependency and the opening angle of the diffused light derived from the second structural region. This is because the can be further improved.
That is, when the second structural region is formed by using a specific (meth) acrylic acid ester polymer as the main component of the columnar material (hereinafter sometimes referred to as the component (A2)). The polymerization rate of the monomer component (hereinafter sometimes referred to as the monomer (A2) component) as the component (A2) is sometimes referred to as the main component of the medium (hereinafter referred to as the (B2) component) by polymerization. The monomer component (hereinafter, also referred to as the monomer (B2) component) may be made faster than the polymerization rate to cause a predetermined difference in the polymerization rate between these monomer components. It is estimated that the polymerizability can be effectively reduced.
As a result, a column structure in which the columnar material composed of the component (A2) is erected in the medium composed of the component (B2) can be efficiently formed by irradiation with active energy rays.
Further, by using a specific (meth) acrylic acid ester as the monomer (A2) component, the compatibility with the monomer (B2) component is reduced to a predetermined range, and the column structure is formed more efficiently. It is estimated that
Furthermore, by using a specific (meth) acrylic acid ester as the monomer (A2) component, the refractive index of the columnar material derived from the (A2) component in the column structure is increased, and the medium derived from the (B2) component The difference from the refractive index of the object can be adjusted to a predetermined value or more.
Therefore, by including a polymer of a specific (meth) acrylic acid ester as the component (A2), in combination with the characteristics of the component (B2) described later, in the medium consisting of the component (B2), from the component (A2) It is possible to efficiently obtain a column structure in which the pillars are forested.
Therefore, it is possible to obtain a second structure region having good incident angle dependency in light transmission and diffusion and having a wide light diffusion incident angle region.
In addition, about the detail of the (meth) acrylic acid ester containing several aromatic rings as a monomer (A2) component which comprises (A2) component, it overlaps with the content of the monomer (A1) component in a 1st structure area | region. Therefore, it is omitted.

(7) -2 Medium In the second structural region, the type of material constituting the medium is not particularly limited, but the main component is preferably a urethane (meth) acrylate polymer.
This is because, with such a material substance, not only can the column structure as the second structural region be efficiently formed, but also the incident angle dependency and the opening angle of the diffused light derived from the second structural region. This is because the can be further improved.
That is, by making the main component of the medium (component (B2)) a urethane (meth) acrylate polymer, the refractive index of the columnar material derived from the component (A2) and the medium derived from the component (B2) In addition to being able to adjust the difference from the refractive index of the medium more easily, the dispersion of the refractive index of the medium derived from the component (B2) can be effectively suppressed, and the second structural region having a predetermined column structure can be further improved. It is because it can obtain efficiently.
In addition, since it overlaps with the content of the monomer (B1) component in a 1st structure area | region about the detail of the urethane (meth) acrylate as a monomer (B2) component which comprises (B2) component, it abbreviate | omits.

5. Total film thickness Moreover, it is preferable to make the total film thickness of the light-diffusion film of this invention into the value within the range of 50-500 micrometers.
This is because when the total film thickness of the light diffusing film is less than 50 μm, the light traveling straight in the column structure and the louver structure increases, and it may be difficult to exhibit light diffusibility. On the other hand, when the total film thickness of the light diffusion film exceeded 500 μm, it was formed at the beginning when the composition for light diffusion film was irradiated with active energy rays to form a column structure and a louver structure. This is because the traveling direction of photopolymerization is diffused by the column structure and the louver structure, and it may be difficult to form the desired column structure and louver structure.
Therefore, the total 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.
In addition, the structure which has a 1st and 2nd structure area | region in the single film may be sufficient as the light-diffusion film of this invention, the film which has only a 1st structure area | region, and a 2nd structure area | region The structure which laminated | stacked the film which has only this may be sufficient.
In particular, when laminating the first and second structural regions, it is possible to fundamentally suppress the occurrence of air bubbles and the like between them, so that a structure in which both structures are formed in a single film is more preferable.
In addition, the first structure region and the second structure region may be provided in the vertical direction sequentially along the film thickness direction of the light diffusion film, and the order and number thereof are not particularly limited. Absent.

6). Combination of tilt angles In the light diffusion film of the present invention, the tilt angle θa of the plate-like region with respect to the film thickness direction in the first structure region and the tilt angle of the columnar object with respect to the film thickness direction in the second structure region The light diffusion characteristics can be changed by adjusting θb.
For example, by overlapping the incident angle dependency of each structural region, it is possible not only to suppress the dispersion of the diffusion characteristics and obtain a good incident angle dependency, but also to effectively spread the diffused light opening angle. Can be spread.
In this case, in the first structural region, the inclination angle θa of the plate-shaped region with respect to the film thickness direction is set to a value within the range of −80 to 80 °, and in the second structural region, the columnar object with respect to the film thickness direction. The inclination angle θb is preferably set to a value in the range of −80 to 80 °, the absolute value of θa−θb is preferably set to a value in the range of 0 to 80 °, and the absolute value of θa−θb is set to 5 to 20 A value within the range of ° is more preferable.
Note that the contents of θa and θb here are as described above.

Further, by shifting the incident angle dependency of each structural region, the light diffusion incident angle region can be effectively and easily expanded.
In this case, in the first structural region, the inclination angle θa of the plate-shaped region with respect to the film thickness direction is set to a value within the range of −80 to 80 °, and in the second structural region, the columnar object with respect to the film thickness direction. The inclination angle θb is preferably set to a value in the range of −80 to 80 °, the absolute value of θa−θb is preferably set to a value in the range of 5 to 60 °, and the absolute value of θa−θb is set to 20 to 45 °. It is more preferable to set the value within the range.

7). Applications Further, as shown in FIG. 10, the light diffusion film of the present invention is preferably used for a reflective liquid crystal display device 100.
This is because the light diffusing film of the present invention efficiently diffuses the external light so that it can be efficiently transmitted and taken into the liquid crystal display device and used as a light source. It is because it can be made.
Therefore, the light diffusing film of the present invention is disposed on the upper surface or the lower surface of the liquid crystal cell 110 composed of the glass plates (104, 108) and the liquid crystal 106, and the specular reflector 107, etc. It is preferable to use as the light diffusion plate 103.
In addition, the light-diffusion film of this invention can also provide a wide viewing angle polarizing plate and a wide visual field phase difference plate by providing to the polarizing plate 101 and the phase difference plate 102. FIG.

[Second Embodiment]
The second embodiment of the present invention provides a light diffusing film having a first structure region for anisotropically diffusing incident light and a second structure region for isotropically diffusing incident light. It is a method, Comprising: It is a manufacturing method of the light-diffusion film characterized by including the following process (a)-(d).
(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) First active energy for the coating layer Irradiate with a line to form a louver structure region in which a plurality of plate-like regions having different refractive indexes as the first structure region are alternately arranged in parallel along the film surface direction in the lower part of the coating layer Step (d) of leaving a louver structure non-formed region in the upper part of the layer (d) A second active energy ray irradiation is further performed on the coating layer, and the louver structure non-formed region is placed in the medium as the second structural region. Step of forming a columnar structure region in which a plurality of pillars having a refractive index different from that of the medium is made up. Hereinafter, the first embodiment of the light diffusion film manufacturing method according to the second embodiment of the present invention Difference from form This will be specifically described with reference to the drawings.

1. Step (a): Preparation Step for Composition for Light Diffusion Film Step (a) is a step for preparing a composition for light diffusion film.
More specifically, it is preferable to stir the monomer (A) component and the monomer (B) component at a high temperature of 40 to 80 ° C. to obtain a uniform mixed solution.
At the same time, other additives such as the component (C) described later are added to the mixed solution as desired, and then diluted as necessary so as to obtain a desired viscosity while stirring until uniform. It is preferable to obtain a solution of the composition for light diffusion film by further adding a solvent.
In addition, a monomer (A) component is a monomer component which becomes a (A) component which comprises the high refractive index part in a 1st and 2nd structure area | region by superposing | polymerizing, and a monomer (B) component superposes | polymerizes. Thus, it is a monomer component that becomes the component (B) constituting the low refractive index portion in the first and second structural regions.
Details of the types of the monomer (A) component and the monomer (B) component are described as the monomers (A1) and (A2) and the components (B1) and (B2) in the first embodiment, respectively. Since it is true, it is omitted.

(1) Refractive index of monomer (A) component Moreover, it is preferable to make the refractive index of a monomer (A) component into the value within the range of 1.5-1.65.
The reason for this is that the refractive index of the part derived from the (A) component and the part derived from the (B) component in the louver structure and the column structure by setting the refractive index of the monomer (A) component within this range. This is because the light diffusion film having the predetermined louver structure and the column structure can be more efficiently obtained by adjusting the difference with the above.
That is, when the refractive index of the monomer (A) component is less than 1.5, the difference from the refractive index of the monomer (B) component becomes too small, making it difficult to obtain the desired incident angle dependency. This is because there are cases. On the other hand, when the refractive index of the monomer (A) component exceeds 1.65, the difference from the refractive index of the monomer (B) component increases, but the viscosity decreases excessively, and the monomer (B) component This is because there is a case where it is difficult to achieve compatibility with.
Therefore, the refractive index of the component (A) is more preferably set to a value within the range of 1.55 to 1.6, and further preferably set to a value within the range of 1.56 to 1.59.
The above-mentioned refractive index of the monomer (A) component means the refractive index of the monomer (A) component before being cured by light irradiation.
And the refractive index of a monomer (A) component can be measured according to JISK0062, for example.

(2) Content of monomer (A) component Moreover, content of monomer (A) component shall be a value within the range of 25-400 weight part with respect to 100 weight part of monomer (B) component mentioned later. Is preferred.
The reason for this is that by setting the content of the monomer (A) component to a value within such a range, while maintaining the miscibility with the monomer (B) component, it is a copolymerization of both components when irradiated with light. This is because the predetermined louver structure and the column structure can be efficiently formed.
That is, when the content of the monomer (A) component is less than 25 parts by weight, the ratio of the (A) component to the monomer (B) component decreases, and the louver structure and the column structure are derived from the (A) component. The width or the like of the portion that has been reduced becomes excessively small compared to the width or the like of the portion derived from the component (B), and it may be difficult to obtain a louver structure and a column structure having good incident angle dependency. Because. Moreover, it is because the length of the louver or the columnar object in the thickness direction of the light diffusion film may be insufficient. On the other hand, when the content of the monomer (A) component exceeds 400 parts by weight, the ratio of the monomer (A) component to the monomer (B) component increases, and the (A) component in the louver structure and column structure The width of the portion derived from the component is excessively large compared to the width of the component derived from the component (B), and conversely, it is difficult to obtain a louver structure and a column structure having a good incident angle dependency. This is because it may become. Moreover, it is because the length of the louver or the columnar object in the thickness direction of the light diffusion film may be insufficient.
Therefore, it is more preferable to set the content of the monomer (A) component to a value within the range of 40 to 300 parts by weight with respect to 100 parts by weight of the monomer (B) component, and within the range of 50 to 200 parts by weight. More preferably, it is a value.

(3) Refractive index of monomer (B) component Moreover, it is preferable to make the refractive index of a monomer (B) component into the value within the range of 1.4-1.5.
The reason for this is that by setting the refractive index of the monomer (B) component to a value within this range, the refractive index of the part derived from the (A) component and the part derived from the (B) component in the louver structure and column structure. This is because the light diffusion film having the predetermined louver structure and the column structure can be more efficiently obtained by adjusting the difference with the above.
That is, when the refractive index of the monomer (B) component is less than 1.4, the compatibility with the monomer (A) component is extremely deteriorated although the difference from the refractive index of the monomer (A) component increases. This is because it may be difficult to form the louver structure and the column structure. On the other hand, when the refractive index of the monomer (B) component exceeds 1.5, the difference from the refractive index of the monomer (A) component becomes too small, making it difficult to obtain the desired incident angle dependency. This is because there may be cases.
Accordingly, the refractive index of the monomer (B) component is more preferably set to a value within the range of 1.45 to 1.49, and further preferably set to a value within the range of 1.46 to 1.48.
The above-described refractive index of the monomer (B) component means the refractive index of the monomer (B) component before being cured by light irradiation.
And also about the refractive index of a monomer (B) component, it can measure according to JISK0062, for example.

(4) Content of monomer (B) component The content of the monomer (B) component is within the range of 20 to 80% by weight relative to the total amount (100% by weight) 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 monomer (B) component is less than 20% by weight, the ratio of the monomer (B) component to the monomer (A) component decreases, and (B) in the louver structure and column structure. The width or the like of the part derived from the component is excessively smaller than the width or the like of the part derived from the component (A), and it becomes difficult to obtain a louver structure and a column structure having a good incident angle dependency. This is because there are cases. Moreover, it is because the length of the louver or the columnar object in the thickness direction of the light diffusion film may be insufficient.
On the other hand, when the content of the monomer (B) component exceeds 80% by weight, the ratio of the monomer (B) component to the monomer (A) component increases, and the (B) component in the louver structure and column structure The width of the portion derived from the component is excessively larger than the width of the portion derived from the component (A), and conversely, it is difficult to obtain a louver structure and a column structure having a good incident angle dependency. This is because it may become. Moreover, it is because the length of the louver or the columnar object in the thickness direction of the light diffusion film may be insufficient.
Therefore, the content of the monomer (B) component is more preferably set to a value within the range of 30 to 70% by weight, and within the range of 40 to 60% by weight, with respect to the total amount of the light diffusing film composition. More preferably, the value of

(5) Photopolymerization initiator Moreover, in the composition for light diffusion films of this invention, it is preferable to contain a photoinitiator as (C) component as needed.
The reason for this is that by containing a photopolymerization initiator, a predetermined louver structure and a column structure can be efficiently formed when the composition for a light diffusing film is irradiated with active energy rays. is there.
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 shall be the value within the range of 0.2-20 weight% with respect to 100 weight% of total amounts of a monomer (A) component and a monomer (B) component. It is preferable that the value be in the range of 0.5 to 15% by weight, more preferably 1 to 10% by weight.

(6) Other additives In addition, other additives can be appropriately added within a range not impairing the effects of the present invention.
Examples of other additives include an antioxidant, an ultraviolet absorber, an antistatic agent, a polymerization accelerator, a polymerization inhibitor, an infrared absorber, a plasticizer, a diluting solvent, and a leveling agent.
In addition, generally content of another additive shall be a value within the range of 0.01 to 5 weight% with respect to 100 weight% of total amounts of a monomer (A) component and a monomer (B) component. Preferably, the value is in the range of 0.02 to 3% by weight, and more preferably in the range of 0.05 to 2% by weight.

2. Step (b): Application Step Step (b) is a step of forming the coating layer 1 by applying the prepared light diffusion film composition to the step sheet 2 as shown in FIG. is there.
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, for the process sheet, a release layer is provided on the application surface side of the composition for the 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.

In addition, as a method for applying the light diffusing film composition on the process sheet, for example, a conventionally known method such as a knife coating method, a roll coating method, a bar coating method, a blade coating method, a die coating method, and a gravure coating method. Can be performed.
At this time, the thickness of the coating layer is preferably set to a value in the range of 100 to 700 μm.

3. Step (c): First active energy ray irradiation step In step (c), first active energy ray irradiation is performed on the coating layer, and the refractive index as the first structure region is formed in the lower portion of the coating layer. This is a step of forming a louver structure region in which a plurality of different plate-like regions are alternately arranged in parallel along the film surface direction and leaving a louver structure unformed region in the upper part of the coating layer.
That is, as shown in FIG. 11B, the active energy ray 50 composed only of direct light whose irradiation angle is controlled is irradiated onto the coating layer 1 formed on the process sheet 2.
More specifically, for example, 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, a commercially available product is an eyepiece). By placing the heat ray cut filter 121 and the light-shielding plate 123 on the graphics (ECS-4011GX, etc.), the active energy ray 50 consisting only of the direct light whose irradiation angle is controlled is taken out. Irradiate the coating layer 1 formed above.
The linear ultraviolet lamp usually has a value in the range of −80 to 80 °, preferably −50 to 50 with respect to the direction (0 °) perpendicular to the longitudinal direction of the process sheet 2 having the coating layer 1. It is installed so as to have a value in the range of °, particularly preferably in the range of -30 to 30 °.
Here, the reason why the linear light source is used is that a louver structure as a first structure region in which plate-like regions having different refractive indexes are alternately arranged in parallel at a constant inclination angle with respect to the film thickness direction. This is because the region can be manufactured efficiently and stably.
More specifically, by using a linear light source, it is substantially parallel light when viewed from the axial direction of the linear light source, and when viewed from a direction perpendicular to the axial direction of the linear light source. Can emit non-parallel light.
At this time, as the irradiation angle of the irradiation light, as shown in FIG. 12B, the irradiation angle θ3 when the angle with respect to the normal of the surface of the coating layer 1 is 0 ° is usually −80 to 80 °. It is preferable to set the value within the range.
The reason for this is that when the irradiation angle is outside the range of −80 to 80 °, the influence of reflection on the surface of the coating layer 1 increases, and it may be difficult to form a sufficient louver structure. Because there is.
The irradiation angle θ3 preferably has a width (irradiation angle width) θ3 ′ of 1 to 80 °.
This is because when the irradiation angle width θ3 ′ is less than 1 °, the interval between the louver structures becomes too narrow, and it may be difficult to obtain a desired first structure region. On the other hand, when the irradiation angle width θ3 ′ exceeds 80 °, the irradiation light is excessively dispersed and it may be difficult to form a louver structure.
Therefore, the irradiation angle width θ3 ′ of the irradiation angle θ3 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 °.

Moreover, as irradiation light, an ultraviolet-ray, an electron beam, etc. are mentioned, However, It is preferable to use an ultraviolet-ray.
This is because, in the case of an electron beam, the polymerization rate is very fast, so that the monomer (A) component and the monomer (B) component cannot be sufficiently separated in the polymerization process, making it difficult to form a louver structure. Because there is. On the other hand, when compared with visible light or the like, ultraviolet rays are more abundant in ultraviolet curing resins that can be cured by irradiation and photopolymerization initiators that can be used. Therefore, monomer (A) component and monomer (B This is because the range of component selection can be expanded.
Moreover, as an irradiation condition of ultraviolet rays, it is preferable to set the illuminance to a value within the range of 0.01 to 50 mW / cm ² .
This is because when the illuminance is less than 0.01 mW / cm ² , the louver structure-unformed region can be sufficiently formed, but it may be difficult to clearly form the louver structure. is there. On the other hand, when the illuminance reaches a value exceeding 50 mW / cm ² , it hardens before the phase separation of the component (A) and the component (B) proceeds, and conversely, it is difficult to clearly form the louver structure. This is because there may be cases.
Therefore, it is more preferably set to a value within the range illuminance of 0.05~20mW / cm ² of ultraviolet, still more preferably a value within the range of 0.1 to 10 MW / cm ^2.

Moreover, it is preferable that the coating layer formed on the process sheet is moved at a speed of 0.1 to 10 m / min to pass the ultraviolet irradiation part by the ultraviolet irradiation apparatus.
The reason for this is that mass productivity may be excessively reduced when the speed is less than 0.1 m / min. On the other hand, when the speed exceeds 10 m / min, the coating layer is hardened, in other words, faster than the formation of the louver structure. This is because it may be sufficient.
Therefore, it is more preferable that the coating layer formed on the process sheet is moved at a speed within the range of 0.2 to 5 m / min, and the ultraviolet irradiation portion by the ultraviolet irradiation device is allowed to pass, More preferably, it is passed at a speed within the range of 3 m / min.

4). Step (d): Second active energy ray irradiation step In step (d), the coating layer is further irradiated with the second active energy ray, and the medium as the second structure region is formed in the louver structure unformed region. This is a step of forming a columnar structure region in which a plurality of columnar objects having different refractive indexes from that of the medium are forested.
That is, parallel light with a high degree of parallelism is applied to the coating layer formed on the process sheet. In the irradiation of the parallel light, the coating layer may be directly irradiated, but it is also preferable that a release film is laminated on the exposed coating layer surface and irradiated through the release film. As a peeling film, the thing which has an ultraviolet-transmitting property among the things described in the said process sheet | seat can be selected suitably.

Here, the direct light from the linear light source used in the first active energy ray irradiation step does not spread in the direction perpendicular to the axial direction of the linear light source, but is substantially parallel. In the direction parallel to the axial direction of the linear light source, the direction of light is not uniform and is random.
On the other hand, the parallel light in the second active energy ray irradiation means substantially parallel light in which the direction of emitted light does not spread even when viewed from any direction.
More specifically, for example, as shown in FIG. 13 (a), the light from the point light source 202 is converted into parallel light by the lens 204 and then applied to the coating layer, or FIGS. 13 (b) to (c). As shown in FIG. 4, it is preferable that the light from the linear light source 206 is collimated by the aggregate 210 of the cylindrical objects 208 and then irradiated to the coating layer.
Therefore, as a specific example of the parallel light irradiation device as shown in FIG. 13A, for example, an ultraviolet spot light source “HYPERCURE 200” manufactured by Yamashita Denso Co., Ltd. and an optional uniform exposure adapter is attached. .

And it is preferable to make the parallelism in parallel light into the value of 10 degrees or less.
The reason for this is that by setting the parallelism to a value of 10 ° or less, a column structure region as a second structure region in which a plurality of pillars are erected at a constant inclination angle with respect to the film thickness direction. It is because it can manufacture efficiently and stably.
That is, if the parallelism exceeds 10 °, the column structure may not be formed.
Therefore, the parallelism of the parallel light is more preferably set to a value of 5 ° or less, and further preferably set to a value of 2 ° or less.

Moreover, as irradiation light, an ultraviolet-ray, an electron beam, etc. are mentioned, However, It is preferable to use an ultraviolet-ray for the same reason as in the 1st active energy ray irradiation process.
Moreover, as an irradiation condition of ultraviolet rays, it is preferable to set the illuminance to a value within the range of 0.01 to 30 mW / cm ² .
This is because when the illuminance is less than 0.01 mW / cm ² , it may be difficult to clearly form the column structure. On the other hand, when the illuminance reaches a value exceeding 30 mW / cm ² , it hardens before the phase separation of the component (A) and the component (B) proceeds, and conversely, it is difficult to clearly form the column structure. This is because there may be cases.
Therefore, it is more preferably set to a value within the range illuminance of 0.05~20mW / cm ² of ultraviolet, still more preferably a value within the range of 0.1 to 10 MW / cm ^2.
The moving speed of the coating layer and the irradiation angle of the irradiation light can be the same as those in the first active energy ray irradiation step.
In addition, it is also preferable to irradiate an active energy ray separately from the first and second active energy ray irradiations so that the integrated light quantity can sufficiently cure the coating layer.
Since the active energy rays at this time are intended to sufficiently cure the coating layer, it is preferable to use light having a random traveling direction rather than parallel light or the like.
Moreover, the light-diffusion film after a photocuring process will be in the state which can be finally used by peeling a process sheet | seat.

  Hereinafter, the light diffusing film and the like of the present invention will be described in more detail with reference to examples.

[Example 1]
1. Synthesis of monomer (B) component In a container, 2 mol of isophorone diisocyanate (IPDI) as component (a) with respect to 1 mol of polypropylene glycol (PPG) having a weight average molecular weight of 9,200 as component (b) And 2 mol of 2-hydroxyethyl methacrylate (HEMA) as component (c) was accommodated, and then reacted according to a conventional method to obtain a polyether urethane methacrylate having a weight average molecular weight of 9,900.

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 diffusion film Next, with respect to 100 parts by weight of the polyether urethane methacrylate having a weight average molecular weight of 9,900 as the monomer (B) component, the following formula (3) as the monomer (A) component: 100 parts by weight of o-phenylphenoxyethoxyethyl acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A-LEN-10) having a weight average molecular weight of 268 and (C) component 2-hydroxy-2-methylpro After adding 10 parts by weight of piophenone, the mixture was heated and mixed under conditions of 80 ° C. to obtain a composition for a light diffusion film. The refractive index of the monomer (A) component and the monomer (B) component was measured according to JIS K0062 using an Abbe refractometer [manufactured by Atago Co., Ltd., product name “Abbe refractometer DR-M2”, Na light source, wavelength: 589 nm]. As a result, they were 1.58 and 1.46, respectively.

3. Application of Composition for Light Diffusion Film Next, the obtained composition for anisotropic light diffusion film was applied to a film-like transparent polyethylene terephthalate film (hereinafter referred to as PET) as a process sheet using an applicator. Thus, a coating layer having a thickness of 200 μm was obtained.

4). Photo-curing of the coating layer (1) First ultraviolet irradiation Next, an ultraviolet irradiation apparatus (eye graphics Co., Ltd.) in which a condensing cold mirror is attached to a linear high-pressure mercury lamp as shown in FIG. Manufactured by ECS-4011GX).
Next, a light shielding plate is installed on the heat ray cut filter frame, and the ultraviolet rays applied to the surface of the coating layer are normal to the laminate composed of the coating layer and PET when viewed from the longitudinal direction of the linear ultraviolet lamp. When the angle was set to 0 °, the irradiation angle of direct ultraviolet rays from the lamp (θ3 in FIG. 12B) was set to be −40 °.
At this time, the height of the lamp from the coating layer was set to 500 mm, and the peak illuminance was set to 1.7 mW / cm ² .
In addition, in order to prevent the reflected light from the light shielding plate, etc. from becoming stray light inside the irradiator and affecting the photocuring of the coating layer, a light shielding plate is also provided near the conveyor, and only ultraviolet rays emitted directly from the lamp are applied. The layer was set to irradiate.
Next, the coating layer was irradiated with ultraviolet rays while moving the coating layer to the right in FIG. 12A at a speed of 0.2 m / min.

(2) Second UV irradiation Next, after passing through a first UV irradiation process with a linear light source, the exposed surface side of the coating layer is a release film having a thickness of 38 μm and having UV transparency (SP manufactured by Lintec Corporation, SP -Laminated by PET 382050).
Next, using an apparatus with a parallelism of 2 ° or less by attaching an optional uniform exposure adapter to an ultraviolet spot light source (HYPERCURE 200, manufactured by Yamashita Denso Co., Ltd.), the incident angle of parallel light becomes 40 °. By irradiating through the release film, a light diffusion film having a total film thickness of 200 μm was obtained.
At that time, the average illuminance was 5 mW / cm ² and the lamp height was 800 mm.
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).
Further, as shown in FIG. 14A, the obtained light diffusion film is confirmed to be a light diffusion film having a louver structure with an inclination angle of −27 ° and a columnar object with an inclination angle of 27 °. did.
In addition, this Fig.14 (a) is a schematic diagram which shows the cross section of the film at the time of cut | disconnecting in a surface perpendicular | vertical to the plate-shaped area | region in a louver structure.
The film thickness of the first structural region was 66 μm, and the film thickness of the second structural region was 38 μm.
Furthermore, the cross-sectional photograph of the obtained light-diffusion film is shown to Fig.15 (a)-(b). FIG. 15 (a) is a cross-sectional photograph of the film cut along a plane perpendicular to the plate-like region in the louver structure, and FIG. 15 (b) is a plane perpendicular to the cut plane in FIG. 15 (a). It is a cross-sectional photograph at the time of cut | disconnecting a film.

5. Measurement Using a variable angle colorimeter (VC-2 manufactured by Suga Test Instruments Co., Ltd.), as shown in FIG. 14 (a), incident on the film from above the obtained light diffusion film. Light was incident at an angle θ1 = 60 ° (C light source, viewing angle 2 °).
Next, the spread of diffused light diffused by the light diffusion film and the distribution of its brightness (%) were measured. The measurement result is shown on the horizontal axis where the value of the vertical axis of the scatter diagram shown in FIG.
That is, the value on the horizontal axis indicates the range of the spread angle (°) of the diffused light, and the color of the plot indicates the brightness (%) of the diffused light diffused at that angle.
Here, the relationship between the color of the plot and the lightness (%) indicates that the lightness of the plot is closer to 100% as the color of the plot is closer to red, and the lightness is 50% as the color of the plot is closer to green. This indicates that the lightness is close to 0% as the color of the plot is closer to dark blue. Details are shown in FIG.
Further, in order to measure the spread of diffused light in the width direction of incident light and the distribution of its brightness (%), the light diffusing film is placed on the same plane around a predetermined point on the surface of the light diffusing film. The same measurement was performed while rotating in the range of -80 to 80 °. The angle of rotation means the angle of rotation when the angle of the light diffusion film at the time of measurement described above is 0 °. For example, the measurement result when the light diffusion film is rotated by 20 ° is shown on the horizontal axis where the value of the vertical axis of the scatter diagram shown in FIG. 14C is 20 °.
Therefore, in the case of the scatter diagram shown in FIG. 14C, for example, a region where diffused light having a brightness of 30% or more is distributed is a region surrounded by a dotted line in FIG.

  Next, as shown in 14 (d) to (k), the incident angles θ1 with respect to the light diffusion film are respectively 50 °, 40 °, 30 °, 0 °, −30 °, −40 °, −50 °, − Instead of 60 °, the spread of diffused light and the distribution of its brightness (%) were measured as in the case of the incident angle θ1 = 60 °.

6). Results As shown in FIGS. 14 (c) to (k), in the light diffusion film of Example 1, in the range of the incident light incident angle θ <b> 1 = 0 °, light diffusion hardly occurs, but the incident angle θ <b> 1. In the range of 30 to 60 °, isotropic light diffusion occurs due to the column structure region, and in the range of the incident angle θ1 = −60 to −30 °, anisotropic light diffusion occurs due to the louver structure region. It can be seen that the light diffusion incident angle region can be effectively expanded by shifting the light diffusion incident angle dependency.

[Example 2]
In Example 2, when the coating layer was cured, the inclination angle of the louver structure was 27 ° and the columnar object was inclined in the same manner as in Example 1 except that θ3 in the first ultraviolet irradiation was changed to 40 °. A light diffusion film as shown in FIG. 16 having an angle of 27 ° was obtained.
Further, the spread of diffused light and the distribution of its brightness (%) were measured in the same manner as in Example 1 except that the incident angle θ1 with respect to the light diffusion film was set to 25 °, 35 °, 45 °, and 55 °, respectively. .
As a result, in the light diffusing film of Example 2, the light diffusing incident angle dependency in the louver structure region and the column structure region is almost overlapped. It became a relatively narrow range.
However, the light diffusion film of Example 2 has high uniformity of diffused light as compared with Comparative Examples 1 and 2 described later, and the spread of diffused light in the width direction of incident light as compared with Comparative Examples 3 and 4. It was confirmed to be large.

[Example 3]
In Example 3, the louver structure is the same as in Example 1 except that θ3 in the first ultraviolet irradiation is changed to 40 ° and the incident angle of the parallel light in the second ultraviolet irradiation is changed to 0 °. A light diffusion film as shown in FIG. 17A having an inclination angle of 27 ° and a columnar object having an inclination angle of 0 ° was obtained.
Moreover, as shown to FIG.17 (b)-(h), incident angle (theta) 1 with respect to a light-diffusion film was set to 0 degree, 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degrees, and 60 degrees, respectively. In the same manner as in Example 1, the spread of diffused light and the distribution of its brightness (%) were measured.
As a result, as shown in FIGS. 17B to 17H, in the light diffusing film of Example 3, light diffusion hardly occurs around the incident angle θ1 = 20 ° of incident light. In the range of incident angle = 0 to 10 °, isotropic light diffusion occurs due to the column structure region, and in the range of incident angle θ1 = 30-60 °, anisotropic light diffusion occurs due to the louver structure region. It can be seen that the light diffusion incident angle region can be effectively expanded by shifting the light diffusion incident angle dependency.

[Example 4]
In Example 4, the louver structure was changed in the same manner as in Example 1 except that θ3 in the first ultraviolet irradiation was changed to 40 ° and the incident angle of the parallel light in the second ultraviolet irradiation was changed to 20 °. A light diffusion film as shown in FIG. 18A having an inclination angle of 27 ° and a columnar object having an inclination angle of 14 ° was obtained.
Further, as shown in FIGS. 18B to 18G, the incident angles θ1 with respect to the light diffusion film were set to 5 °, 15 °, 25 °, 35 °, 45 °, and 55 °, respectively. Similar to 1, the spread of diffused light and its brightness (%) distribution were measured.
As a result, as shown in FIGS. 18B to 18G, in the light diffusion film of Example 4, the isotropic light due to the column structure region is in the range of the incident light incident angle θ1 = 5 to 25 °. Diffusion occurs, and in the range of the incident angle θ1 = 25 to 55 °, anisotropic light diffusion is caused by the louver structure region, and by partially overlapping while shifting the light diffusion incident angle dependency by the two structure regions, It can be seen that the light diffusion incident angle region can be effectively expanded.

[Comparative Example 1]
In Comparative Example 1, the first ultraviolet irradiation is not performed, and the incident angle of the parallel light of the second ultraviolet irradiation is changed to 0 °, as shown in FIG. In addition, a light diffusion film having only a column structure with an inclination angle of 0 ° over the entire region corresponding to the first structure region and the second structure region was obtained.
In addition, as shown in FIGS. 19B to 19J, the incident angles θ1 with respect to the light diffusion film are set to 20 °, 15 °, 10 °, 5 °, 0 °, −5 °, −10 °, − Except for setting to 15 ° and −20 °, the spread of diffused light and the distribution of lightness (%) were measured in the same manner as in Example 1.
As a result, as shown in FIGS. 19B to 19J, the light diffusing film of Comparative Example 1 has only a column structure, so that the light diffusing incident angle region is θ1 = −15 to 15 °. The range was relatively narrow.
Further, it can be seen that the central portion of the diffused light has a particularly high brightness compared with other portions, and the uniformity of the diffused light is low.

[Comparative Example 2]
In Comparative Example 2, the first ultraviolet irradiation is not performed, and the incident angle of the parallel light of the second ultraviolet irradiation is changed to 40 ° as shown in FIG. In addition, a light diffusion film having only a column structure with an inclination angle of 27 ° was obtained over the entire region corresponding to the first structure region and the second structure region.
Moreover, as shown in FIGS. 20B to 20K, the incident angles θ1 with respect to the light diffusion film are 15 °, 20 °, 25 °, 30 °, 35 °, 40 °, 45 °, 50 °, respectively. Except for 55 ° and 60 °, the spread of diffused light and the distribution of lightness (%) were measured in the same manner as in Example 1.
As a result, as shown in FIGS. 20B to 20K, the light diffusion film of Comparative Example 2 has only a column structure, and thus the light diffusion incident angle region is θ1 = 25 to 60 °. The range became a relatively narrow range.
In addition, it can be seen that the central portion of the diffused light has particularly high brightness compared to other portions, and the uniformity of the diffused light is low.

[Comparative Example 3]
In Comparative Example 3, as shown in FIG. 21A, the first ultraviolet irradiation θ3 is changed to 0 °, and the second ultraviolet irradiation is not performed. As a structure region, a light diffusion film having a louver structure region having an inclination angle of 0 ° and a louver structure unformed region above the louver structure region was obtained.
Moreover, as shown to FIG.21 (b)-(h), incident angle (theta) 1 with respect to a light-diffusion film was 20 degrees, 15 degrees, 10 degrees, 5 degrees, 0 degrees, -5 degrees, and -10 degrees, respectively. Other than that, the spread of diffused light and the distribution of its brightness (%) were measured in the same manner as in Example 1.
As a result, as shown in FIGS. 21B to 21H, the light diffusion film of Comparative Example 3 has only a louver structure, and thus the light diffusion angle region is θ1 = −5 to 15 °. The range became a relatively narrow range.
Further, it can be seen that the anisotropy of the diffused light is large and the spread of the diffused light in the width direction of the incident light is small.

[Comparative Example 4]
In Comparative Example 4, as shown in FIG. 22A, the first ultraviolet irradiation θ3 is changed to 40 °, and the second ultraviolet irradiation is not performed. A light diffusion film having a louver structure region having an inclination angle of 27 ° as a structure region and a louver structure non-formation region above the louver structure region was obtained.
Further, as shown in FIGS. 22B to 22I, the incident angles θ1 with respect to the light diffusion film are 25 °, 30 °, 35 °, 40 °, 45 °, 50 °, 55 °, and 60 °, respectively. A light diffusing film was produced in the same manner as in Example 1.
Moreover, since the light-diffusion film of the comparative example 4 has only a louver structure as FIG.22 (b)-(i) shows, a light-diffusion angle area | region is. A relatively narrow range of θ1 = 30 to 60 ° was obtained.
Further, it can be seen that the anisotropy of the diffused light is large and the spread of the diffused light in the width direction of the incident light is small.

As described above in detail, according to the present invention, in the film, a louver structure region for anisotropically diffusing incident light and a column structure region for isotropically diffusing incident light are formed into a film. By providing the upper and lower sides along the thickness direction, it is possible to obtain a light diffusion film having a good incident angle dependency and a wide light diffusion incident angle region.
Therefore, the light diffusion film and the like of the present invention can be provided for a viewing angle control film, a viewing angle widening film, and a projection screen in addition to the light control film in the reflective liquid crystal device. Is expected to contribute significantly.

1: coating layer, 2: process sheet, 10: first structure region (anisotropic light diffusion film), 12: plate-like region having a relatively high refractive index (high refractive index portion), 13: louver structure region, 13 ′: Boundary surface of louver structure, 14: plate-like region (low refractive index portion) having a relatively low refractive index, 20: second structure region (isotropic light diffusion film), 22: columnar object, 24: columnar object 30: Light diffusion film, 50: Active energy ray, 120: Ultraviolet irradiation device, 121: Heat ray cut filter, 122: Cold mirror, 123: Light shielding plate, 125: Linear ultraviolet lamp, 100: Reflective type Liquid crystal display device, 101: polarizing plate, 102: retardation plate, 103: light diffusion plate, 104: glass plate, 105: color filter, 106: liquid crystal, 107: specular reflection plate, 108: glass plate, 110: liquid Cell, 202: a point light source, 204: lens, 206: linear ultraviolet lamp, 208: tubular product, 210: aggregate of tubular material

Claims (9)

A light diffusing film having a first structural region for anisotropically diffusing incident light and a second structural region for isotropically diffusing incident light,
The first structure region is a louver structure region in which a plurality of plate-like regions having different refractive indexes are alternately arranged in parallel along the film surface direction,
The light diffusion film, wherein the second structure region is a column structure region in which a plurality of columnar objects having a refractive index different from that of the medium are provided in the medium.   In the first structure region, the widths of the plate-like regions having different refractive indexes are set to values within the range of 0.1 to 15 μm, respectively, and the plate-like region is inclined at a constant angle with respect to the film thickness direction. The light diffusion film according to claim 1, wherein the light diffusion film is arranged in parallel.   In the first structural region, among the plate-like regions having different refractive indexes, the main component of the plate-like region having a high refractive index is a polymer of (meth) acrylic acid ester containing a plurality of aromatic rings, The light diffusion film according to claim 1 or 2, wherein a main component of the plate-like region having a low refractive index is a urethane (meth) acrylate polymer.   The light diffusion film according to any one of claims 1 to 3, wherein the thickness of the first structure region is set to a value within a range of 5 to 495 µm.   In the second structure region, the maximum diameter in the cross section of the columnar body is set to a value within the range of 0.1 to 15 μm, the distance between the columnar bodies is set to a value within the range of 0.1 to 15 μm, and The light diffusing film according to any one of claims 1 to 4, wherein the plurality of columnar objects are forested at a constant inclination angle with respect to the film thickness direction.   In the second structural region, the main component of the columnar material is a (meth) acrylic acid ester containing a plurality of aromatic rings, and the main component of the medium is a urethane (meth) acrylate. The light diffusion film according to any one of claims 1 to 5.   The light diffusion film according to any one of claims 1 to 6, wherein the thickness of the second structural region is set to a value within a range of 5 to 495 µm. A method for producing a light diffusion film having a first structural region for anisotropically diffusing incident light and a second structural region for isotropically diffusing incident light,
The manufacturing method of the light-diffusion film characterized by including the following process (a)-(d).
(A) Step of preparing a composition for light diffusion film (b) Step of applying the composition for light diffusion film to a step sheet to form a coating layer (c) First step for the coating layer Irradiation with active energy rays is performed to form a louver structure region in which a plurality of plate-like regions having different refractive indexes as first structure regions are alternately arranged in parallel along the film surface direction in the lower portion of the coating layer. And a step (d) of leaving a louver structure unformed region in an upper part of the coating layer. (D) irradiating the coating layer with a second active energy ray to form a second structure region in the louver structure unformed region. Forming a columnar structure region in which a plurality of columnar objects having different refractive indexes from the medium are formed in the medium   The method for producing a light diffusing film according to claim 8, wherein the second active energy ray irradiation is performed by irradiating parallel light having a parallelism value of 10 ° or less.