JP5883630B2 - Manufacturing method of light diffusion film - Google Patents

Description

The present invention relates to a method for producing a light diffusion film.
In particular, the present invention relates to a method of manufacturing a light diffusion film that can diffuse incident light into a polygonal shape.

Conventionally, light diffusing films have been used for lighting fixtures and building materials, but recently, they are also used for light diffusion in displays such as liquid crystal displays.
In addition, there are various modes for such a light diffusion film, and in particular, by irradiating a specific photocurable composition with active energy rays as parallel light over the entire surface, the film thickness of the film. A light diffusion film formed by forming a column structure region in which a plurality of columnar objects having a refractive index different from that of the medium is formed in the medium along the direction is disclosed (for example, Patent Documents 1 to 3). reference).

  That is, in Patent Document 1, a composition containing a photocurable compound is provided on a sheet, the composition is cured by irradiating the sheet with a parallel light beam from a predetermined direction P, and parallel to the predetermined direction P inside the sheet. A method of manufacturing a diffusion medium (light diffusion film) for forming an assembly of a plurality of extending rod-shaped cured regions, and a cylindrical shape arranged in parallel to a predetermined 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 Patent Document 2, a linear light source is disposed so as to face and separate from the photocurable resin composition film, and the linear light source is moved while moving at least one of the photocurable resin composition film and the linear light source. Is a manufacturing apparatus for forming a light control film (light diffusion film) by irradiating light from a photocurable resin composition film, wherein the axial direction and the moving direction of the linear light source intersect each other, A plurality of opposed thin plate-like light shielding members are provided between the photocurable resin composition film and the linear light source at a predetermined interval in a direction substantially perpendicular to the moving direction, and the light curable resin of the light shielding member. An apparatus for manufacturing a light control film is disclosed in which one side facing the composition film is provided in the same direction as the moving direction.

  Further, in Patent Document 3, 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. 4095573 (claims, drawings, etc.) JP 2009-173018 A (Claims, drawings, etc.) JP 2008-256930 A (Claims, drawings, etc.)

However, since the light diffusion film having the column structure region disclosed in Patent Documents 1 to 3 can only diffuse the isotropic light in an isotropic manner, there is a problem that the application target is limited.
For example, when the light diffusing film disclosed in Patent Documents 1 to 3 is applied as a light diffusing film for a backlight to a generally distributed rectangular display, light is evenly distributed to the four corners of the display. There was a problem that it was difficult to diffuse.

Therefore, the present inventors have made diligent efforts in view of the circumstances as described above, and, using an array light source in which a plurality of micro light sources are arrayed on a coating layer made of the composition for a light diffusing film, a predetermined amount is used. The present invention has been completed by finding that a light diffusing film capable of diffusing incident light into a polygonal shape such as a square or a hexagon can be obtained by irradiating with active energy rays under the above conditions. .
That is, an object of the present invention is to manufacture a light diffusing film having a predetermined internal structure composed of a plurality of regions having different refractive indexes inside the film and capable of diffusing incident light into a polygonal shape. It is to provide a method.

According to this invention, it is a manufacturing method of the light-diffusion film for diffusing incident light into polygonal shape, Comprising: The manufacturing method of the light-diffusion film characterized by including the following process (a)-(c) Provided and can solve the above-mentioned problems.
(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) A plurality of micro light sources for the coating layer Using an array light source that is arranged, the active energy rays from adjacent micro-light sources are irradiated so that they overlap on the surface of the coating layer. Irradiating active energy rays with high illuminance, photocuring while phase-separating starting from the overlapping portion of the active energy rays, and forming the coating layer as a light diffusion film having an internal structure composed of a plurality of regions having different refractive indexes Step That is, if it is the manufacturing method of the light-diffusion film of this invention, with respect to the composition for light-diffusion films, the arrangement | sequence light source which arranges a several micro light source Is used to irradiate active energy rays so that active energy rays from adjacent micro-light sources overlap on the surface of the coating layer, so that a light diffusion film having a predetermined internal structure can be produced efficiently.
Therefore, according to the method for producing a light diffusion film of the present invention, it is possible to efficiently produce a light diffusion film that can diffuse incident light into a polygonal shape due to the predetermined internal structure.

In the following description, major terms used to describe the present invention are defined as follows.
That is, in the present invention, “polygonal light diffusion film” means a light diffusion film that can diffuse incident light into a polygonal shape, and “polygonal shape” includes “linear”. Shall be.
Therefore, for example, a light diffusing film that can diffuse incident light linearly is referred to as a “linear light diffusing film”, and light diffusion that can diffuse incident light into a square or regular hexagon. The films may be referred to as “square light diffusion film” and “regular hexagonal light diffusion film”, respectively.
In the present invention, the “film surface direction” means an xy plane direction perpendicular to the film thickness direction when the film thickness direction is the z-axis.
In the present invention, the “light diffusion incident angle region” means an incident light corresponding to emitting diffused light when the angle of incident light from a point light source is changed with respect to the light diffusing film. It shall mean an angular range.
On the other hand, in the present invention, the “light diffusion angle region” means an angle range of diffused light obtained by fixing a point light source at an angle at which incident light is most diffused with respect to the light diffusion film. .
Here, in the light diffusing film according to the present invention, the width of the light diffusing angle region (hereinafter sometimes referred to as “diffuse light opening angle”) and the width of the light diffusing incident angle region are approximately It will be the same.
Furthermore, “good incident angle dependency” means that the distinction between the light diffusion incident angle region and the non-diffuse incident angle region where the incident light is transmitted without being diffused is clearly controlled. .

Moreover, when implementing the manufacturing method of the light-diffusion film of this invention, it is preferable that the several micro light source in an arrangement | sequence light source is a several LED light source.
This is because the wavelength of active energy rays, the degree of overlap on the coating layer surface and the illuminance distribution can be arbitrarily and easily controlled by carrying out in this way.

Moreover, when implementing the manufacturing method of the light-diffusion film of this invention, it is preferable that the several micro light source in an arrangement | sequence light source is arranged so that the center distance between adjacent micro light sources may become fixed.
By carrying out in this way, the overlapping state of the active energy rays on the surface of the coating layer becomes uniform, and a light diffusion film having a predetermined internal structure can be produced more efficiently.

In carrying out the method for producing a light diffusing film of the present invention, when a plurality of micro light sources in an array light source connect adjacent micro light sources with line segments, a plurality of squares and lines having one side as a line segment It is preferable that a plurality of equilateral triangles or one line segment with a minute side be arranged so as to be drawn.
By implementing in this way, the light-diffusion film which can carry out the light diffusion of incident light in square shape, a regular hexagon shape, or a linear shape can each be manufactured efficiently.

Moreover, when implementing the manufacturing method of the light-diffusion film of this invention, it is preferable to make the distance between centers of adjacent minute light sources into the value within the range of 3-25 mm in an arrangement | sequence light source.
By carrying out in this way, the active energy ray overlapping degree on the surface of the coating layer can be adjusted to a suitable range, and a light diffusion film having a predetermined internal structure can be more efficiently produced.

In carrying out the method for producing a light diffusing film of the present invention, in the step (c), the half angle of the directivity angle of the active energy ray irradiated from the minute light source is set to a value within the range of 2 to 50 °. preferable.
By carrying out in this way, the active energy ray overlapping degree on the surface of the coating layer can be adjusted to a suitable range, and a light diffusion film having a predetermined internal structure can be more efficiently produced.

Moreover, when implementing the manufacturing method of the light-diffusion film of this invention, in a process (c), it is preferable to make the space | interval of the surface of an application layer and the lower end of an array light source into the value within the range of 5-100 cm. .
By carrying out in this way, the active energy ray overlapping degree on the surface of the coating layer can be adjusted to a suitable range, and a light diffusion film having a predetermined internal structure can be more efficiently produced.

Moreover, when implementing the manufacturing method of the light-diffusion film of this invention, it is preferable to make the peak wavelength of the active energy ray irradiated from a micro light source into the value within the range of 200-410 nm in a process (c).
By implementing in this way, the light-diffusion film which has a predetermined internal structure can be manufactured still more efficiently.

Fig.1 (a)-(b) is a figure provided in order to demonstrate the outline of the internal structure in a linear light-diffusion film. FIGS. 2A to 2B are diagrams provided for explaining the incident angle dependency and the linear light diffusion in the linear light diffusion film. FIGS. 3A to 3B are diagrams provided to explain the outline of the internal structure of the square light diffusion film. FIG. 4 is a diagram for explaining the square light diffusion in the square light diffusion film. FIGS. 5A to 5B are diagrams provided to explain the outline of the internal structure of the regular hexagonal light diffusion film. FIG. 6 is a diagram for explaining regular hexagonal light diffusion in a regular hexagonal light diffusion film. FIGS. 7A to 7C are diagrams provided for explaining the coating process and the active energy ray irradiation process. FIGS. 8A to 8D are diagrams for explaining the overlapping state of active energy rays when the arrangement of the micro light sources in the array light source is array 1, and the internal structure of the light diffusion film at that time. is there. FIGS. 9A to 9D are diagrams for explaining the overlapping state of active energy rays when the arrangement of the micro light sources in the arrangement light source is arrangement 2, and the internal structure of the light diffusion film at that time. is there. FIGS. 10A to 10D are views for explaining the overlapping state of the active energy rays and the internal structure of the light diffusion film at that time when the arrangement of the micro light sources in the arrangement light source is the arrangement 3. FIG. . FIGS. 11A to 11C are diagrams provided for explaining other variations of the arrangement of the micro light sources in the array light source. FIG. 12 is a diagram provided to explain the half angle of the directivity angle of the active energy ray irradiated from the micro light source. FIG. 13 is a diagram for explaining an application example of the light diffusion film obtained by the present invention in the reflective liquid crystal display device. FIGS. 14A to 14B are diagrams for explaining the array light source used in the first embodiment. FIGS. 15A to 15B are a photograph and a diagram provided to illustrate light diffusion by the light diffusion film obtained in Example 1. FIG. FIGS. 16A and 16B are diagrams provided to explain the array light source used in the second embodiment. FIGS. 17A to 17B are laser micrographs obtained by photographing the light diffusion film obtained in Example 2. FIG. 18 (a) to 18 (b) are a photograph and a diagram provided to illustrate light diffusion by the light diffusion film obtained in Example 2. FIG. FIGS. 19A and 19B are diagrams for explaining the array light source used in Comparative Example 1. FIG. 20 (a) to 20 (b) are a photograph and a diagram provided for illustrating light diffusion by the light diffusion film obtained in Comparative Example 1. FIG.

Embodiment of this invention is a manufacturing method of the light-diffusion film for diffusing incident light into polygonal shape, Comprising: The manufacturing method of the light-diffusion film characterized by including the following process (a)-(c) It is.
(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) A plurality of micro light sources for the coating layer Using an array light source that is arranged, the active energy rays from adjacent micro-light sources are irradiated so that they overlap on the surface of the coating layer, and the coating layer has an internal structure composed of a plurality of regions having different refractive indexes. Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings as appropriate. First, in order to facilitate understanding of the description, first, light diffusion by a light diffusion film is performed. After explaining the basic principle by taking a linear light diffusion film as an example, a more complicated polygonal light diffusion mechanism will be explained by taking a square light diffusion film as an example.

1. First, the basic principle of light diffusion by the light diffusion film will be described with reference to FIGS.
First, FIG. 1 (a) shows a top view (plan view) of a linear light diffusion film 10a having a louver structure in the film, and FIG. 1 (b) shows FIG. 1 (a). A cross-sectional view of the light diffusion film 10a when the linear light diffusion film 10a is cut in the vertical direction along the dotted line AA and the cut surface is viewed from the arrow direction is shown.
FIG. 2 (a) shows the general view of the linear light diffusion film 10a and the spread of diffused light when viewed from directly above, and FIG. 2 (b) shows the linear light of FIG. 2 (a). Sectional drawing at the time of seeing the diffusion film 10a from X direction is represented.
As shown in the plan view of FIG. 1A, the linear light diffusion film 10a includes a plate-like region 12a having a relatively high refractive index and a plate-like region having a relatively low refractive index in the film surface direction. 14a and a louver structure 13a arranged alternately in parallel.
Further, as shown in the cross-sectional view of FIG. 1B, each of the high refractive index plate region 12a and the low refractive index plate region 14a has a predetermined thickness, and linear light diffusion. Even in the vertical direction of the film 10a, the state of being alternately arranged in parallel is maintained.

Thereby, as shown to Fig.2 (a), when an incident angle is in a light diffusion incident angle area | region, it is estimated that incident light is diffused by the linear light-diffusion film 10a.
That is, as shown in FIG. 1B, the incident angle of incident light on the linear light diffusion film 10a is a value within a predetermined angle range from parallel to the boundary surface 13a ′ of the louver structure 13a, 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-shaped region 12a 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 linear light diffusion film 10a (52 ', 54').
On the other hand, when the incident angle of the incident light with respect to the linear light diffusion film 10a deviates from the light diffusion incident angle region, the incident light 56 is diffused by the linear light diffusion film 10a as shown in FIG. It is estimated that it passes through the linear light diffusion film 10a as it is (56 ').

Based on the basic principle described above, the linear light diffusion film 10a provided with the predetermined louver structure 13a can exhibit incident angle dependency in light transmission and diffusion as shown in FIG. 2A, for example. It becomes.
In addition, as shown in FIG. 2A, the linear light diffusion film 10a emits light even if the incident angle is different when the incident angle of the incident light is included in the light diffusion incident angle region. Almost the same light diffusion can be performed on the surface side.
Therefore, it can be said that the obtained linear light diffusion film 10a also has a light condensing function that concentrates light at a predetermined location.

In addition, as shown to Fig.2 (a), the light diffusion incident angle area | region is determined for every linear light-diffusion film 10a by the refractive index difference, inclination angle, etc. of the louver structure in the linear light-diffusion film 10a. It is an angle region.
In addition, the direction change of the incident light inside the plate-like region 12a having a high refractive index in the louver structure is a step index type in which the direction changes linearly and zigzags due to total reflection as shown in FIG. In addition to this, a gradient index type in which the direction changes in a curved shape may be considered.

Moreover, as shown to Fig.2 (a), the linear light-diffusion film 10a which has a louver structure as an internal structure diffuses incident light linearly.
Here, “linear light diffusion” means that when light is diffused by a film as shown in FIG. 2 (a), the light in the plane parallel to the film in the diffused emitted light is reflected. It means that the diffusion state (the shape of the spread of diffused light) has a property of becoming linear depending on the direction in the same plane.
More specifically, as shown in FIG. 2 (a), among the components included in the incident light, the component perpendicular to the direction of the louver structure extending in the film surface direction is selectively diffused. Of the components included in the incident light, components that are parallel to the direction of the louver structure extending in the film surface direction are less likely to cause light diffusion, so that linear light diffusion is realized.
Therefore, the shape of the spread of the diffused light in the linear light diffusing film 10a is substantially elliptical as shown in FIG.

In addition, as described above, the incident light component contributing to the linear light diffusion is a component perpendicular to the direction of the louver structure extending mainly in the film surface direction, and as shown in FIG. In the present invention, the “incident angle θ1” of incident light means an 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 °.
In the present invention, the “diffuse light opening angle” is the width of the light diffusion angle region, as shown in FIG. 2B, from the direction X parallel to the direction of the louver structure extending in the film surface direction In the case of viewing a cross section of the film, it means an opening angle θ2 of diffused light with respect to incident light having a predetermined incident angle θ1.

2. Polygonal Light Diffusion Mechanism Next, a more complicated polygonal light diffusion mechanism by the light diffusion film obtained by the manufacturing method of the present invention will be described with reference to FIGS. Will be described in detail.
In addition, although the linear light-diffusion film 10a shown in FIGS. 1-2 is also contained in the light-diffusion film obtained by the manufacturing method of this invention, the mechanism of the polygonal light diffusion more complicated than linear light diffusion is demonstrated. Therefore, the square light diffusion film 10b will be described as an example.

First, FIG. 3A shows a top view (plan view) of the square light diffusion film 10b, and FIG. 3B shows the square light diffusion film 10b shown in FIG. Sectional drawing of the square-shaped light-diffusion film 10b at the time of cut | disconnecting perpendicularly along dotted line AA and dotted line BB and seeing a cut surface from the arrow direction is shown.
FIG. 4 shows an overall view of the square light diffusing film 10b and how the incident light is diffused by the square light diffusing film 10b when viewed from directly above (the shape of the spread of the diffused light). .

As shown in the plan view of FIG. 3A, the square light diffusion film 10b includes a plate-like region having a relatively high refractive index and a plate-like region having a relatively low refractive index in the film surface direction. Are provided with an internal structure 13b woven by being alternately arranged in parallel in each of the horizontal direction X and the vertical direction Y.
Note that the plate-like regions having a relatively high refractive index that are alternately arranged in parallel in each of the horizontal direction X and the vertical direction Y intersect each other to form the mesh region 12b, but the plate-like regions having a relatively low refractive index. It is presumed that the region is divided by the mesh region 12b having a relatively high refractive index and forms a polygonal region (rectangular region) 14b.
Further, as shown in FIG. 3B, the high refractive index mesh area 12b and the low refractive index polygon area 14b each have a predetermined thickness, and the film of the square light diffusion film 10b. Even in the thickness direction, the state of being alternately arranged in parallel is maintained.

Accordingly, as shown in FIG. 4, when the incident angle is within the light diffusion incident angle region, the incident light is square light diffusion film 10b according to the basic principle of light diffusion described with reference to FIGS. Therefore, it is estimated that light is diffused in a square shape.
In addition to the square light diffusing film 10b, various polygonal light diffusing films can be manufactured. For example, the refractive index is relatively high as shown in FIGS. In the case of a regular hexagonal light diffusing film 10c having an internal structure 13c composed of a high mesh region 12c and a polygonal region (hexagonal region) 14c having a relatively low refractive index, as shown in FIG. Can diffuse into a regular hexagon.
Hereinafter, the manufacturing method of the light-diffusion film which concerns on this embodiment is explained in full detail.

3. 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 two polymerizable compounds having different refractive indexes under a high temperature condition of 40 to 80 ° C. to obtain a uniform mixed solution.
At the same time, an additive such as a photopolymerization initiator is added to the mixed solution as desired, and then a dilution solvent is further added 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 adding.
Hereinafter, the step (a) will be described more specifically.

(1) High Refractive Index Polymerizable Compound (1) -1 Type Among two polymerizable compounds having different refractive indices, the polymerizable compound having the higher refractive index (hereinafter sometimes referred to as component (A)). Although the kind of is not specifically limited, It is preferable to make the main component into the (meth) acrylic acid ester containing a some aromatic ring.
The reason for this is that by including a specific (meth) acrylic acid ester as the component (A), the polymerization rate of the component (A) is referred to as a polymerizable compound having a lower refractive index (hereinafter referred to as component (B). It is presumed that the polymerization rate between these components can be effectively reduced by making the polymerization rate faster than the polymerization rate of the above component) and causing a predetermined difference in the polymerization rate between these components. It is.
As a result, when photocured, a predetermined internal structure composed of a high refractive index region derived from the component (A) and a low refractive index region derived from the component (B) can be efficiently formed.
In addition, by including a specific (meth) acrylic acid ester as the component (A), the monomer stage has sufficient compatibility with the component (B), but a plurality of stages in the polymerization process. Then, it is estimated that compatibility with (B) component can be reduced to a predetermined range, and a predetermined internal structure can be formed more efficiently.
Furthermore, by including a specific (meth) acrylic acid ester as the component (A), the refractive index of the high refractive index region derived from the component (A) in the internal structure is increased, and the component is derived from the component (B). The difference from the refractive index of the low refractive index region can be adjusted to a value greater than or equal to a predetermined value.
Therefore, by including a specific (meth) acrylic acid ester as the component (A), combined with the characteristics of the component (B) described later, a light diffusion film having a predetermined internal structure composed of regions having different refractive indexes. Can be obtained efficiently.
In addition, "(meth) acrylic acid ester containing a plurality of aromatic rings" means a compound having a plurality of aromatic rings in the ester residue portion of (meth) acrylic acid ester.
“(Meth) acrylic acid” means both acrylic acid and methacrylic acid.

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

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

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

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

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

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

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

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

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

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

(1) -3 Refractive index Moreover, it is preferable to make the refractive index of (A) component into the value within the range of 1.5-1.65.
The reason for this is that by setting the refractive index of the component (A) to a value within this range, the refractive index of the high refractive index region derived from the component (A) and the low refractive index region derived from the component (B) This is because a light diffusion film having a predetermined internal structure can be more efficiently obtained by adjusting the difference from the refractive index more easily.
That is, when the refractive index of the component (A) is less than 1.5, the difference from the refractive index of the component (B) becomes too small, and it may be difficult to obtain an effective light diffusion angle region. Because there is. On the other hand, when the refractive index of the component (A) exceeds 1.65, the difference with the refractive index of the component (B) increases, but even an apparent compatibility state with the component (B) is formed. This is because it may be difficult.
Therefore, the refractive index of the component (A) is more preferably set to a value within the range of 1.55 to 1.6, and further preferably set to a value within the range of 1.56 to 1.59.
In addition, the refractive index of (A) component mentioned above means the refractive index of (A) component before hardening by light irradiation.
The refractive index can be measured according to, for example, JIS K0062.

(1) -4 Content Further, the content of the component (A) in the composition for light diffusion film is set to a value within the range of 25 to 400 parts by weight with respect to 100 parts by weight of the component (B) described later. It is preferable.
The reason for this is that when the content of the component (A) is less than 25 parts by weight, the ratio of the component (A) to the component (B) decreases, and the high refractive index region derived from the component (A) This is because the width becomes excessively small as compared with the width of the low refractive index region derived from the component (B), and it may be difficult to obtain a predetermined internal structure having good incident angle dependency. . Moreover, it is because the length of the predetermined internal structure in the thickness direction of a light-diffusion film becomes inadequate, and may not show light diffusibility. On the other hand, when the content of the component (A) exceeds 400 parts by weight, the ratio of the component (A) to the component (B) increases, and the width of the high refractive index region derived from the component (A) However, the width of the low refractive index region derived from the component (B) is excessively large, and conversely, it may be difficult to obtain a predetermined internal structure having good incident angle dependency. It is. Moreover, it is because the length of the predetermined internal structure in the thickness direction of a light-diffusion film becomes inadequate, and may not show light diffusibility.
Therefore, it is more preferable to set the content of the component (A) to a value within the range of 40 to 300 parts by weight with respect to 100 parts by weight of the component (B), and a value within the range of 50 to 200 parts by weight. More preferably.

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

First, urethane (meth) acrylate is formed from (a) a compound containing at least two isocyanate groups, (b) polyalkylene glycol, and (c) hydroxyalkyl (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 especially preferable that it is an alicyclic polyisocyanate.
This is because, in the case of alicyclic polyisocyanates, compared to aliphatic polyisocyanates, it is easy to provide a difference in the reaction rate of each isocyanate group due to the conformation and the like.
This suppresses that the (a) component reacts only with the (b) component, or the (a) component reacts only with the (c) component, and the (a) component is replaced with the (b) component and (C) It can react reliably with a component and generation | occurrence | production of an extra by-product can be prevented.
As a result, it is possible to effectively suppress variations in the refractive index of the low refractive index region derived from the component (B) in the predetermined internal structure.

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

Among the components that form urethane (meth) acrylate, examples of the polyalkylene glycol (b) include polyethylene glycol, polypropylene glycol, polybutylene glycol, polyhexylene glycol, and the like. Particularly preferred is glycol.
This is because polypropylene glycol can be handled without a solvent because of its low viscosity.
Moreover, if it is a polypropylene glycol, when it hardens | cures (B) component, it becomes a favorable soft segment in the said hardened | cured material, and it is because the handling property and mounting property of a light-diffusion film can be improved effectively. is there.
In addition, the weight average molecular weight of (B) component can be mainly 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, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3 -Hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc. are mentioned.
In addition, from the viewpoint of reducing the polymerization rate of the obtained urethane (meth) acrylate and more efficiently forming a predetermined internal structure, hydroxyalkyl methacrylate is more preferable, and 2-hydroxyethyl methacrylate is particularly preferable. Is more preferable.

Moreover, the synthesis | combination of the urethane (meth) acrylate by (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 components (a) This is because it is possible to efficiently synthesize urethane (meth) acrylate in which the hydroxyl group of component (c) reacts with and binds to the other isocyanate group possessed by each.
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.

(2) -2 Weight average molecular weight Moreover, it is preferable to make the weight average molecular weight of (B) component into the value within the range of 3,000-20,000.
This is because, by setting the weight average molecular weight of the component (B) within a predetermined range, a predetermined difference is caused in the polymerization rate of the component (A) and the component (B), and the copolymerizability of both components is effectively improved. This is because it can be lowered.
As a result, when photocured, the first and second louver structure regions in which the high refractive index region derived from the component (A) and the low refractive index region derived from the component (B) are alternately extended are efficiently obtained. Can be well formed.
That is, when the weight average molecular weight of the component (B) is less than 3,000, the polymerization rate of the component (B) is increased to be close to the polymerization rate of the component (A). This is because polymerization may easily occur, and it may be difficult to efficiently form a predetermined internal structure. On the other hand, when the weight average molecular weight of the component (B) exceeds 20,000, it becomes difficult to form a predetermined internal structure composed of the component (A) and the component (B). This is because the component (A) may be precipitated at the coating stage.
Therefore, the weight average molecular weight of the component (B) is more preferably set to a value within the range of 5,000 to 15,000, and further preferably set to a value within the range of 7,000 to 13,000.
In addition, the weight average molecular weight of (B) component can be measured using a gel permeation chromatography (GPC).

(2) -3 Refractive index Moreover, it is preferable to make the refractive index of (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 component (B) to a value within this range, the refractive index of the high refractive index region derived from the component (A) and the refractive index of the low refractive index region derived from the component (B) This is because the light diffusion film having a predetermined polygonal region can be more efficiently obtained by adjusting the difference between the two.
That is, when the refractive index of the component (B) is less than 1.4, the difference with the refractive index of the component (A) increases, but the compatibility with the component (A) is extremely deteriorated, and a predetermined This is because the internal structure may not be formed. On the other hand, if the refractive index of the component (B) exceeds 1.5, the difference from the refractive index of the component (A) becomes too small, making it difficult to obtain the desired incident angle dependency. Because there is.
Therefore, the refractive index of the component (B) is more preferably set to a value within the range of 1.45 to 1.49, and further preferably set to a value within the range of 1.46 to 1.48.
In addition, the refractive index of (B) component mentioned above means the refractive index of (B) component before hardening by light irradiation.
The refractive index can be measured, for example, according to JIS K0062.

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

(2) -4 Content The content of the component (B) in the composition for light diffusion film is within the range of 10 to 80% by weight with respect to 100% by weight of the total amount of the composition for light diffusion film. It is preferable to use a value.
The reason for this is that when the content of the component (B) is less than 10% by weight, the ratio of the component (B) to the component (A) decreases, and the low refractive index region derived from the component (B) This is because the width becomes excessively small as compared with the width of the high refractive index region derived from the component (A), and it may be difficult to obtain a predetermined internal structure having good incident angle dependency. . Moreover, it is because the length of the predetermined internal structure in the thickness direction of the light diffusion film may be insufficient. On the other hand, when the content of the component (B) exceeds 80% by weight, the ratio of the component (B) to the component (A) increases, and the width of the low refractive index region derived from the component (B) However, the width of the high refractive index region derived from the component (A) is excessively large, and conversely, it may be difficult to obtain a predetermined internal structure having good incident angle dependency. It is. Moreover, it is because the length of the predetermined internal structure in the thickness direction of the light diffusion film may be insufficient.
Therefore, it is more preferable to make content of (B) component into the value within the range of 20 to 70 weight% with respect to 100 weight% of the total amount of the composition for light diffusion films, More preferably, the value is within the range.

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

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

(4) Other additives 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 general, the content of the other additives is preferably set to a value within the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the total amount of the component (A) and the component (B). A value within the range of 0.02 to 3 parts by weight is more preferable, and a value within the range of 0.05 to 2 parts by weight is even more preferable.

4). 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.
Moreover, when the process mentioned later is considered, as the process sheet | seat 2, it is preferable that it is a film excellent in the dimensional stability with respect to a heat | fever or an active energy ray.
Preferred examples of such a film include polyester films, polyolefin films, and polyimide films among those described above.

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

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

5. Step (c): Active Energy Ray Irradiation Step In step (c), as shown in FIGS. 7B to 7C, an array light source 20 in which a plurality of micro light sources 25 are arrayed with respect to the coating layer 1 is formed. The active energy rays 50 from the adjacent minute light sources 25 are irradiated so that the active energy rays 50 overlap each other on the surface of the coating layer 1, and the coating layer 1 has the internal structure 13 composed of a plurality of regions having different refractive indexes. It is the process of setting it as the light-diffusion film 10 to have.

(1) Array Light Source (1) -1 Micro Light Source The array light source 20 of the present invention is characterized in that a plurality of micro light sources 25 are arrayed as shown in FIGS.
The reason for this is that, in the case of an array light source in which a plurality of micro light sources are arrayed, the application layer is irradiated by irradiating active energy rays from adjacent micro light sources so as to overlap each other on the surface of the application layer, as will be described later. This is because a light diffusion film having a predetermined internal structure composed of a plurality of regions having different refractive indexes can be obtained.
Here, the “micro light source” means a light source in which the surface area of the light emitting portion is less than 54 cm ² , more preferably less than 6 cm ² .
Moreover, as a planar size when the micro light source is viewed from the light irradiation direction, the maximum diameter is preferably less than 3 cm, and more preferably less than 1 cm.

Moreover, it is preferable that the several micro light source in an arrangement | sequence light source is a several LED light source.
The reason for this is that if the light source is an LED light source, the direction of light emission is determined, so it is easy to control the directivity angle of the active energy ray, and since the size is small, the light direction by the reflector or the like is easy to control, Furthermore, the wavelength of the active energy ray can be selected, and application to a desired mode such as ozone-less or heat-ray-free becomes easy.
Of the LED light sources, a bullet-type LED light source is preferable.
The reason for this is that a bullet-type LED light source includes a directivity angle control part in itself, so that the directivity angle of the active energy ray can be controlled without requiring a separate directivity angle control device. This is because it can.

(1) -2 Array It is preferable that the plurality of micro light sources in the array light source are arranged so that the distance between the centers of the adjacent micro light sources is constant.
The reason for this is that by arranging the adjacent micro-light sources to have a constant center-to-center distance, the active energy rays overlap uniformly on the surface of the coating layer, and light diffusion having a predetermined internal structure. This is because the film can be produced more efficiently.
Hereinafter, the arrangements 1 to 3 will be described as more specific arrangement modes.

(I) Sequence 1
First, as shown in FIG. 8A, when a plurality of minute light sources 25 in the array light source 20 connect adjacent minute light sources with a line segment 26, a plurality of squares with the line segment 26 as one side are drawn. It is preferable that the arrangement 1 is arranged as described above.
This is because a square light diffusion film capable of diffusing incident light in a square shape can be efficiently manufactured by arranging the micro light sources in this manner.
That is, in the case of the arrangement 1, as shown in FIG. 8B, the spread 50 ′ of active energy rays irradiated from the respective micro light sources 25 overlap so as to draw a constant pattern on the surface of the coating layer 1. This is because it can be done.
More specifically, in FIG. 8B, the solid line 52 is drawn so that the spread of the active energy rays 51 ′ irradiated from the respective micro light sources 25 passes through the center of the overlapping portion. It can be seen that 52 depicts regularly arranged squares.
That is, when the array light source 20 of the array 1 is used, the surface of the coating layer 1 is generally irradiated with active energy rays having a higher illuminance than the other portions on the portion corresponding to the solid line 52. It will be understood.
Therefore, the solid line 52 can be said to be a contour line of the active energy ray intensity.

As a result, in the coating layer 1, as shown in FIG. 8C, starting from the portion corresponding to the solid line 52, the component (A) having a higher polymerization rate than the component (B) is preferentially photocured. It is estimated that a high refractive index mesh region 12b derived from the component (A) and a low refractive index square region 14b derived from the component (B) will be formed while starting and phase separation between the components. The
FIG. 8D is an enlarged view when one square surrounded by a solid line 52 in FIG. 8C is taken out.
Further, FIG. 8B shows a case where the spread of active energy rays irradiated from adjacent micro light sources overlaps, but this is an example, and active energy rays irradiated from non-adjacent micro light sources are shown as an example. The spreads may overlap, and the same applies to FIGS. 9B and 10B described later.

(Ii) Sequence 2
Also, as shown in FIG. 9A, when a plurality of minute light sources 25 in the array light source 20 connect adjacent minute light sources with line segments, a plurality of equilateral triangles with the line segment 26 as one side is drawn. It is also preferable to take sequence 2 that is arranged as described above.
This is because a regular hexagonal light diffusing film capable of diffusing incident light into a regular hexagonal shape can be efficiently manufactured by arranging the micro light sources in this manner.
That is, in the case of the arrangement 2, as shown in FIG. 9B, the spread 50 ′ of active energy rays irradiated from the respective micro light sources 25 overlap so as to draw a constant pattern on the surface of the coating layer 1. This is because it can be done.
More specifically, in FIG. 9B, the solid line 52 is drawn so that the spread 50 'of the active energy rays irradiated from the respective micro light sources 25 passes through the center of the overlapping portion. It is understood that 52 depicts regular hexagons arranged regularly.
That is, when the array light source 20 of the array 2 is used, on the surface of the coating layer 1, the active energy rays having a higher illuminance than the other portions are generally irradiated to the portion corresponding to the solid line 52. It will be understood.
Therefore, the solid line 52 can be said to be a contour line of the active energy ray intensity.

As a result, in the coating layer 1, as shown in FIG. 9C, starting from the portion corresponding to the solid line 52, the component (A) having a higher polymerization rate than the component (B) is preferentially photocured. It is estimated that a high refractive index mesh region 12c derived from the component (A) and a low refractive index hexagonal region 14c derived from the component (B) will be formed through phase separation between components. Is done.
FIG. 9D is an enlarged view when one regular hexagon surrounded by the solid line 52 in FIG. 9C is taken out.

(Iii) Sequence 3
As shown in FIG. 10A, when a plurality of micro light sources 25 in the array light source 20 connect adjacent micro light sources with a line segment 26, they are arranged so that one line segment is drawn. It is preferable to take the sequence 3 shown below.
This is because a linear light diffusion film capable of diffusing incident light linearly can be efficiently manufactured by arranging the micro light sources in this manner.
That is, in the case of the arrangement 3, as shown in FIG. 10B, the spreads 50 ′ of active energy rays irradiated from the respective micro light sources 25 overlap so as to draw a constant pattern on the surface of the coating layer 1. It is because it can be made.
More specifically, in FIG. 10B, a solid line 52 is drawn with respect to the outline of the overlapping of the spreads 50 ′ of active energy rays irradiated from the respective micro light sources 25. It can be understood that although the active energy ray from each micro light source 25 is rounded corresponding to the spread 50 ', a line segment extending substantially in the vertical direction is drawn as a whole.
That is, when the array light source 20 of the array 3 is used, it is understood that the solid line 52 is generally a contour line of the active energy ray intensity on the surface of the coating layer 1.

As a result, in the coating layer 1, as shown in FIG. 10 (c), starting from the portion corresponding to the solid line 52, the component (A) having a higher polymerization rate than the component (B) is preferentially photocured. Thus, it is presumed that the plate-like region 12a having a high refractive index derived from the component (A) and the plate-like region 14b having a low refractive index derived from the component (b) are formed while undergoing phase separation between the components. Is done.
In addition, FIG.10 (d) is an enlarged view at the time of taking out the area | region derived from one micro light source 25 enclosed with the continuous line 52 in FIG.10 (c).

(Iv) Other arrangements The arrangement of the micro light sources in the present invention may be an arrangement other than the above-described arrangements 1 to 3.
More specifically, when adjacent minute light sources are connected by a line segment, the arrangement is such that a plurality of quadrangles, triangles, or one line segment with the line segment as one side are drawn, and adjacent The arrangement may be such that the distance between the centers of the minute light sources to be performed is not constant.
However, in this case, the light diffusing performance of the obtained light diffusing film is non-uniform and non-uniform within the light diffusing film.
Furthermore, as shown in FIG. 11A, when adjacent minute light sources 25 are connected by a line segment 26, an arrangement may be made in which a plurality of hexagons having the line segment 26 as one side are drawn. Then, as shown in FIGS. 11B to 11C, when adjacent minute light sources 25 are connected by a line segment 26, an arrangement is drawn in which a plurality of octagons and quadrangles having the line segment 26 as one side are drawn. It may be.
In addition, when the arrangement | sequence of a micro light source like FIG.11 (a)-(c) is taken, the shape of the diffused light in the polygonal-shaped light-diffusion film obtained is a hexagonal light diffusion in the case of Fig.11 (a). In the case of FIGS. 11B and 11C, it is expected that a square with a little corner (an octagon close to a square) is formed.

(1) -3 Center-to-center distance In the array light source, the center-to-center distance between adjacent minute light sources is preferably set to a value in the range of 3 to 25 mm.
The reason for this is that the distance between the centers of adjacent micro light sources is set to a value within this range, thereby adjusting the overlapping state of active energy rays on the surface of the coating layer to a suitable range, and light having a predetermined internal structure. This is because the diffusion film can be manufactured more efficiently.
That is, if the distance between the centers is less than 3 mm, the micro light sources may physically collide with each other and may not be arranged. On the other hand, when the center-to-center distance exceeds 25 mm, it becomes difficult to obtain an overlap of active energy rays, and it becomes difficult to form a predetermined internal structure in the light diffusion film. Is not realized, and it may be a non-uniform and non-uniform light diffusion film.
Therefore, in the array light source, the center-to-center distance between adjacent minute light sources is more preferably set to a value within the range of 4 to 20 mm, and further preferably set to a value within the range of 5 to 15 mm.

(1) -4 Half angle of directivity angle Moreover, it is preferable to make half angle (theta) 3 of the directivity angle of the active energy ray irradiated from a micro light source into the value within the range of 2-50 degrees.
Here, the directivity angle means that when the relative light intensity distribution diagram as shown in FIG. 12 is drawn for the LED light source, half the light intensity (relative light intensity 50%) is obtained from the brightest point (relative light intensity 100%). Means the angle value (the angle formed by two points having a relative luminous intensity of 50% on the relative luminous intensity distribution curve and a zero point at the center of the lower end of the distribution diagram).
Therefore, the half angle of the directivity angle means half of the directivity angle, and means θ3 in FIG.
The reason why it is preferable to set the half angle of the directivity angle within the above-described range is that the half angle θ3 of the directivity angle of the active energy ray irradiated from the minute light source is set to a value within the above range, thereby This is because the overlapping state of the active energy rays can be adjusted to a suitable range, and a light diffusion film having a predetermined internal structure can be produced more efficiently.
That is, when the half angle θ3 of the directivity angle is less than 2 °, it becomes difficult to obtain the overlap of the active energy rays, and it becomes difficult to form a predetermined internal structure in the light diffusion film. This is because shape light diffusion is not realized, and a non-uniform and non-uniform light diffusion film may be obtained. On the other hand, when the half angle θ3 of the directivity angle exceeds 50 °, the directivity of the active energy ray is extremely reduced, and it may be difficult to form a predetermined internal structure in the light diffusion film. Because there is.
Therefore, it is more preferable to set the half angle θ3 of the directivity angle of the active energy ray irradiated from the minute light source to a value within the range of 3 to 40 °, and further preferably within the range of 5 to 30 °.
Note that the half angle θ3 of the directivity angle of the active energy ray emitted from the minute light source is the active energy ray when the irradiation direction of the active energy ray from the center of the minute light source 25 is 0 ° as shown in FIG. It is an angle indicating the spread of.

(2) Irradiation distance Moreover, it is preferable to make the space | interval of the surface of an application layer and the lower end of an arrangement | sequence light source into the value within the range of 5-100 cm.
The reason for this is that by adjusting the distance between the surface of the coating layer and the lower end of the array light source within such a range, the overlap of active energy rays on the surface of the coating layer is adjusted to a suitable range, and a predetermined range is obtained. This is because a light diffusion film having an internal structure can be produced more efficiently.
That is, when the distance is less than 5 cm, it is difficult to obtain active energy ray overlap, making it difficult to form a predetermined internal structure in the light diffusion film, and realizing the desired polygonal light diffusion. This is because there is a case where the light diffusion film is not uniform and non-uniform. On the other hand, when the interval exceeds 100 cm, the number of micro light sources involved in the overlap of active energy rays is extremely reduced, and the directivity of the active energy rays becomes extremely weak. This is because it may be difficult to form the structure.
Therefore, the distance between the surface of the coating layer and the lower end of the array light source is more preferably set to a value within the range of 8 to 90 cm, and further preferably set to a value within the range of 10 to 80 cm.

(3) Peak wavelength Moreover, it is preferable to make the peak wavelength of the active energy ray irradiated from a micro light source into the value within the range of 200-410 nm.
This is because the light diffusion film having a predetermined internal structure can be more efficiently produced by setting the peak wavelength of the active energy ray to a value within such a range.
That is, when the peak wavelength is less than 200 nm, polymerization initiation by the photopolymerization initiator may be difficult to occur appropriately. On the other hand, even when the peak wavelength exceeds 410 nm, polymerization initiation by the photopolymerization initiator may be difficult to occur appropriately.
Therefore, the peak wavelength of the active energy ray irradiated from the minute light source is more preferably set to a value within the range of 250 to 405 nm, and further preferably set to a value within the range of 300 to 400 nm.

(4) Illuminance Moreover, it is preferable to make the illuminance on the coating layer surface in active energy ray irradiation into the value within the range of 0.1-10 mW / cm < ² >.
This is because a predetermined internal structure can be efficiently formed by setting the illuminance in active energy ray irradiation to a value within such a range.
That is, if the illuminance is less than 0.1 mW / cm ² , it may be difficult to clearly form a predetermined internal structure. On the other hand, when the illuminance value exceeds 10 mW / cm ² , the coating layer is cured before phase separation occurs between the high refractive index polymerizable compound and the low refractive index polymerizable compound, This is because it may be difficult to form a predetermined internal structure necessary for the polygonal light diffusion.
Therefore, it is more preferably set to a value within the range of the illuminance of 0.3~7mW / cm ² of the coating layer surface of the active energy ray irradiation, a value within a range of 0.5~5mW / cm ² Is more preferable.

(5) Light quantity Moreover, it is preferable to make the light quantity in the surface of the coating layer in active energy ray irradiation into the value within the range of 10-500 mJ / cm < ² >.
This is because a predetermined internal structure can be efficiently formed by setting the amount of light in active energy ray irradiation to a value within this range.
That is, when the amount of light is less than 10 mJ / cm ² , it may be difficult to sufficiently extend the predetermined internal structure from the top to the bottom.
On the other hand, when the amount of light exceeds 500 mJ / cm ² , abnormalities such as yellowing may occur in the obtained light diffusion film.
Therefore, it is more preferably set to a value within the range of the amount of light the 20~200mJ / cm ² of the coating layer surface of the active energy ray irradiation, still more preferably a value within the range of 30~150mJ / cm ^2.

(6) Suppression of oxygen inhibition Moreover, it is preferable to irradiate the coating layer with active energy rays in a non-oxygen atmosphere.
This is because, by performing active energy ray irradiation in a non-oxygen atmosphere, the influence of oxygen inhibition can be suppressed and a predetermined internal structure can be efficiently formed.
That is, if the active energy ray irradiation is performed in an oxygen atmosphere instead of a non-oxygen atmosphere, a predetermined internal structure is formed at a very shallow position near the surface of the coating layer if the irradiation is performed with high illuminance. This is because it may be difficult to obtain a difference in refractive index necessary for light diffusion.
On the other hand, when irradiated with low illuminance, it may be difficult to form a predetermined internal structure due to the influence of oxygen inhibition.
Note that “under a non-oxygen atmosphere” means a condition where the upper surface of the coating layer is not in direct contact with an oxygen atmosphere or an atmosphere containing oxygen.
Therefore, for example, it is possible to irradiate active energy rays in a “non-oxygen atmosphere” in a state where a film is laminated on the upper surface of the coating layer, or nitrogen is purged by replacing air with nitrogen gas. This corresponds to the irradiation of active energy rays.

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

Moreover, as an active energy ray permeable sheet, it is preferable that the surface centerline average roughness of the side which does not contact a coating layer is a value of 2 micrometers or less, and it is especially preferable that it is a value of less than 1 micrometer.
This is because such a center line average roughness can effectively prevent the active energy rays from being diffused by the active energy ray transmitting sheet, and can efficiently form a predetermined internal structure.
The centerline average roughness can be determined according to JIS B 0633.
From the same viewpoint, the haze value of the active energy ray-transmitting sheet is preferably a value within a range of 0 to 8%, and particularly preferably a value within a range of 0.1 to 5%.
The haze value can be obtained according to JIS K 7136.

Moreover, it is preferable that the image definition (slit width: 0.125 mm, 0.25 mm, 0.5 mm, 1 mm, and 2 mm) of the active energy ray transmitting sheet is a value within a range of 200 to 500, A value in the range of 300 to 490 is particularly preferable.
The reason for this is that if the image definition is in such a range, the active energy rays can be transmitted through the coating layer without being lost by the sheet, and a predetermined internal structure can be efficiently formed. Because.
The image definition can be obtained according to JIS K 7374.
From the same viewpoint, the transmittance of the active energy ray-transmitting sheet with respect to light having a wavelength of 360 nm is preferably a value in the range of 30 to 100%, and a value in the range of 45 to 95%. Particularly preferred.

(7) Apparatus Moreover, although it does not specifically limit as an apparatus for irradiating an active energy ray with respect to a coating layer, For example, it is set as an aspect as shown to FIG.7 (b)-(c). It is preferable.
That is, it is preferable that the mounting unit 60 for mounting the coating layer 1 is provided and the array light source 20 is provided above the mounting unit 60 so as to face the mounting unit 60.
Further, the mounting portion 60 and / or the array light source 20 can be moved up and down so that the distance between the surface of the coating layer 1 and the lower end of the array light source 60 can be adjusted as appropriate. Preferably there is.
In addition, the apparatus for irradiating an active energy ray with respect to an application layer may be aspects other than a stationary type as shown in FIG.7 (b)-(c), for example, the belt conveyor which can move an application layer in parallel The array light source may also be movable in parallel so as to follow the movement of the coating layer.
Further, following the movement of the coating layer, the micro light sources constituting the array light source may be appropriately turned on and off.
Furthermore, the coating layer and the array light source may be opposed to each other with a predetermined inclination angle. In this case, a predetermined internal structure having a certain inclination angle is formed in the obtained light diffusion film.

6). Complete curing step In addition to the step (c), it is also preferable to irradiate an active energy ray so that the coating layer has a light amount that can be sufficiently cured.
Since the active energy ray at this time is intended to sufficiently cure the coating layer, it is preferable to use irradiation light whose traveling direction is random.
Moreover, the light-diffusion film after a complete hardening process will be in the state which can be finally used now by peeling a process sheet | seat.

7). Specific structure of light diffusing film (1) Internal structure (1) -1 Refractive index In a predetermined internal structure, a difference in refractive index between regions having different refractive indexes, that is, a refractive index in a high refractive index region and a low refractive index. The difference from the refractive index of the refractive index region is preferably set to a value of 0.01 or more.
The reason is that the difference in refractive index is set to a value of 0.01 or more, whereby incident light is stably reflected within a predetermined internal structure, and the incident angle dependency in the light diffusion film is further improved. It is because it can do.
Therefore, the difference in refractive index between regions having different refractive indexes in a predetermined internal structure is preferably 0.05 or more, and more preferably 0.1 or more.
In addition, although the difference of the refractive index mentioned above is so preferable that it is large, from a viewpoint of selecting the material which can form a predetermined | prescribed internal structure, about 0.3 is considered to be an upper limit.

In the predetermined internal structure, the refractive index of the high refractive index region is preferably set to a value in the range of 1.5 to 1.7.
This is because when the refractive index of the high refractive index region is less than 1.5, the difference from the low refractive index region becomes too small, making it difficult to obtain a predetermined internal structure. is there. On the other hand, when the refractive index of the high refractive index region exceeds 1.7, the compatibility between the material substances in the light diffusion film composition may be excessively lowered.
Therefore, the refractive index of the high refractive index region in the predetermined internal structure is more preferably set to a value in the range of 1.52 to 1.65, and is set to a value in the range of 1.55 to 1.6. Further preferred.
In addition, the refractive index of a high refractive index area | region can be measured according to JISK0062, for example.

In the predetermined internal structure, the refractive index of the low refractive index region is preferably set to a value in the range of 1.4 to 1.5.
The reason for this is that when the refractive index of the low refractive index region 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 region exceeds 1.5, the difference from the refractive index of the high refractive index region becomes too small, and it may be difficult to obtain a predetermined internal structure. Because there is.
Accordingly, the refractive index of the low refractive index region in the predetermined internal structure is more preferably set to a value in the range of 1.42 to 1.48, and is set to a value in the range of 1.44 to 1.46. Further preferred.
In addition, the refractive index in a low refractive index area | region can be measured according to JISK0062, for example.

(1) -2 Width In the predetermined internal structure as shown in FIGS. 1B, 3B, and 5B, the widths of the high refractive index region 12 and the low refractive index region 14 are set as follows. It is preferable to set the value within the range of 0.1 to 15 μm.
This is because, by setting the width of these regions to a value in the range of 0.1 to 15 μm, incident light is stably reflected within a predetermined internal structure, and the incident angle dependency in the light diffusion film is increased. This is because it can be improved more effectively.
That is, if the widths of the high refractive index region and the low refractive index region are less than 0.1 μm, it may be difficult to show light diffusion regardless of the incident angle of incident light. On the other hand, when the width of the high refractive index region and the low refractive index region exceeds 15 μm, the light traveling straight in the predetermined internal structure increases, and the uniformity of the diffused light may deteriorate. .
Therefore, in the predetermined internal structure, the width of the high refractive index region and the low refractive index region is more preferably set to a value within a range of 0.5 to 10 μm, and a value within a range of 1 to 5 μm. Is more preferable.
In addition, the width and length of the high refractive index region and the low refractive index region constituting the predetermined internal structure can be measured by observing the film cross section with an optical digital microscope.

(2) Film thickness Moreover, it is preferable to make the film thickness of the light-diffusion film of this invention into the value within the range of 30-250 micrometers.
This is because when the total film thickness of the light diffusion film becomes a value of less than 30 μm, the incident light traveling straight through the predetermined internal structure increases, and it may be difficult to show light diffusion. On the other hand, when the film thickness of the light diffusion film exceeds 250 μm, the internal structure formed at the beginning is formed when the composition for light diffusion film is irradiated with active energy rays to form a predetermined internal structure. This is because the traveling direction of photopolymerization may diffuse due to the above, and it may be difficult to form a predetermined internal structure.
Therefore, the film thickness of the light diffusion film is more preferably set to a value within the range of 40 to 200 μm, and further preferably set to a value within the range of 50 to 150 μm.

8). Applications Further, as shown in FIG. 13, the light diffusion film obtained by the present invention is preferably used for the reflective liquid crystal display device 100.
The reason for this is that the light diffusing film obtained according to the present invention is efficient so that external light can be collected and efficiently transmitted to be taken into the liquid crystal display device and used as a light source. This is because it can be diffused.
Therefore, the light diffusing film obtained by 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, the specular reflection plate 107, etc. 100 is preferably used as the light diffusion plate 103.
The light diffusion film obtained by the present invention can be applied to the polarizing plate 101 and the retardation plate 102 to obtain a wide viewing angle polarizing plate and a wide viewing phase retardation plate, a projection screen, It can also be applied to lighting fixtures.

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

[Example 1]
1. (B) Synthesis of 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 after accommodating 2 mol of 2-hydroxyethyl methacrylate (HEMA) as (c) component, it superposed | polymerized in accordance with the conventional method, and obtained the polyether urethane methacrylate of the weight average molecular weight 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 Light Diffusion Composition Next, the weight represented by the following formula (3) as the component (A) with respect to 100 parts by weight of the polyether urethane methacrylate having a weight average molecular weight of 9,900 as the component (B) obtained. 100 parts by weight of o-phenylphenoxyethoxyethyl acrylate having an average molecular weight of 268 (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A-LEN-10) and 2-hydroxy-2-methylpropiophenone 5 as component (C) After adding a weight part, it heat-mixed on 80 degreeC conditions, and obtained the composition for light-diffusion films.
The refractive indices of the components (A) and (B) were 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]. , 1.58 and 1.46, respectively.

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

4). Next, an array light source as shown in FIG. 14A was prepared. FIG. 14 (b) shows an enlarged view of a group of nine micro light sources included in the array light source of FIG. 14 (a).
The specific configuration of such an array light source is as follows.
-Micro light source arrangement mode: Delta arrangement (when adjacent micro light sources are connected by a line segment, an array in which a plurality of equilateral triangles having one line as one side is drawn)
・ Center-to-center distance between adjacent micro light sources: 6 mm
-Number of micro light sources arranged: 10 vertical x 25 horizontal-Type of micro light source: LED light source (Nitride Semiconductor Co., Ltd., NS355L-5RLO)
-Diameter of micro light source: 5 mm
・ Peak wavelength of active energy rays irradiated from a micro light source: 355 nm
・ Half angle of the directivity angle of active energy rays irradiated from a micro light source: 7.5 °

Next, on the exposed surface side of the coating layer, as an active energy ray transmitting sheet, a release film having a thickness of 38 μm having UV transmittance (manufactured by Lintec Corporation, SP-PET 382050; centerline average roughness on the surface on the UV irradiation side) 0.01 μm, haze value 1.80%, image definition 425, transmittance of wavelength 360 nm) was laminated.
Next, in the apparatus as shown in FIGS. 7B to 7C, the active light beams are arranged in a state in which the array light source described above is arranged in parallel so that the distance between the surface of the coating layer and the array light source is 26 cm. Was irradiated for 2 minutes to obtain a light diffusion film having a thickness of 200 μm.
In addition, the film thickness of the light-diffusion film was measured using the constant-pressure thickness measuring device (Takara Seisakusho Co., Ltd. product, Teclock PG-02J).

  Moreover, the obtained light-diffusion film has the internal structure which consists of a high refractive index network area | region and a low refractive index hexagonal area | region as shown to Fig.5 (a)-(b). It was confirmed.

5. Measurement Using a conoscope (manufactured by autonic-MELCHERS Gmbh), a direction perpendicular to the film surface with respect to the film from the lower side of the obtained light diffusion film, that is, the side in contact with the process sheet Incident light from (incident angle θ1 = 0 °) was incident with a laser pointer having a wavelength of 500 nm.
A photograph of the diffused light obtained at this time is shown in FIG. 15 (a), and an outline of the diffused light in FIG. 15 (a) is shown in FIG. 15 (b).

[Example 2]
In Example 2, when the coating layer was photocured, a light diffusion film was obtained in the same manner as in Example 1, except that an array light source as shown in FIGS.
Moreover, the obtained light-diffusion film has an internal structure which consists of a high refractive index network area | region and a low refractive index square area | region as shown to Fig.3 (a)-(b). It was confirmed.
Moreover, the laser micrograph of the light-diffusion film obtained in Example 2 is shown to Fig.17 (a)-(b). FIG. 17A is a laser micrograph of a cut surface obtained by cutting the light diffusion film along a plane substantially parallel to the film surface, and FIG. 17B is a diagram showing the light diffusion film cut along a plane perpendicular to the film surface. It is a laser micrograph of a cut surface.
Furthermore, the photograph of the diffused light in the light-diffusion film obtained in Example 2 is shown in FIG. 18 (a), and the outline of the diffused light in FIG. 18 (a) is shown in FIG. 18 (b).

The specific configuration of the array light source used in Example 2 is as follows.
-Micro light source arrangement mode: square array (when adjacent micro light sources are connected by a line segment, an array in which a plurality of squares with a line segment as one side are drawn)
・ Distance between centers of adjacent minute light sources: 7 mm
-Number of micro light sources arranged: 10 vertical x 20 horizontal-Type of micro light source: LED light source (Nitride Semiconductor Co., Ltd., NS375-5RLM)
-Diameter of micro light source: 5 mm
・ Peak wavelength of active energy rays irradiated from a micro light source: 375 nm
・ Half angle of active energy ray irradiated from micro light source: 15 °

[Comparative Example 1]
In Comparative Example 1, when the coating layer is photocured, an array light source as shown in FIGS. 19A to 19B is used, and the distance between the surface of the coating layer and the array light source is 15 cm. A light diffusing film was obtained in the same manner as in Example 1 except that they were arranged in parallel.
Moreover, since the obtained light-diffusion film did not overlap the active energy rays derived from each micro-light source, the predetermined internal structure as shown in FIGS. 1, 3 and 5 was not formed, and another random interior It was confirmed that a structure was formed.
Moreover, the photograph of the diffused light in the light-diffusion film obtained by the comparative example 1 is shown to Fig.20 (a), and what showed the outline of the diffused light in Fig.20 (a) is shown in FIG.20 (b).

The specific configuration of the array light source used in Comparative Example 1 is as follows.
-Micro light source arrangement mode: square array (when adjacent micro light sources are connected by a line segment, an array in which a plurality of squares with a line segment as one side are drawn)
・ Center-to-center distance between adjacent micro light sources: 14 mm
-Number of micro light sources arranged: 5 vertical x 10 horizontal-Types of micro light sources: LED light source (Nitride Semiconductor Co., Ltd., NS375-5RLM)
-Diameter of micro light source: 5 mm
・ Peak wavelength of active energy rays irradiated from a micro light source: 375 nm
・ Half angle of active energy ray irradiated from micro light source: 15 °

As described above in detail, according to the present invention, an active energy ray is used under a predetermined condition by using an array light source in which a plurality of micro light sources are arrayed on a coating layer made of the composition for light diffusion film. , The light diffusing film capable of diffusing incident light into a polygonal shape such as a square or hexagon can be obtained.
More specifically, a light diffusing film having a predetermined internal structure composed of a plurality of regions having different refractive indexes inside the film, and capable of diffusing incident light into a polygonal shape is obtained. Became.
Therefore, the method for producing a light diffusing film of the present invention can be applied to a viewing angle control film, a viewing angle control film, a viewing angle widening film, a projection screen, and a lighting fixture in addition to a light control film in a reflective liquid crystal device. It is expected to contribute significantly to the improvement of quality and the yield.

1: coating layer, 2: process sheet, 10: (polygonal shape) light diffusion film, 10a: linear light diffusion film, 10b: square light diffusion film, 10c: regular hexagonal light diffusion film, 12 (12a, 12b) 12c): a plate-like region having a relatively high refractive index, 13 (13a, 13b, 13c): a predetermined internal structure, 14 (14a, 14b, 14c): a plate-like region having a relatively low refractive index, 20 : Array light source, 25: minute light source, 26: line segment, 50: active energy ray, 50 ': spread of active energy ray, 52: solid line, 60: mounting portion, 100: reflective liquid crystal display device, 101: polarized light 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 crystal cell

Claims (8)

A method for producing a light diffusion film for diffusing incident light into a polygonal shape,
The manufacturing method of the light-diffusion film characterized by including the following process (a)-(c).
(A) Step of preparing a composition for light diffusing film (b) Step of applying the composition for light diffusing film to a step sheet and forming a coating layer (c) A plurality of fine particles for the coating layer By using an array light source in which light sources are arrayed and irradiating active energy rays so that active energy rays from adjacent micro light sources overlap on the surface of the coating layer , other portions are overlapped with the active energy rays. The active energy rays having a large illuminance compared with the above, and photocuring while phase-separating starting from a portion where the active energy rays overlap, and the coating layer has an internal structure composed of a plurality of regions having different refractive indexes Process to make light diffusion film   The method for producing a light diffusion film according to claim 1, wherein the plurality of micro light sources in the array light source are a plurality of LED light sources.   The method for producing a light diffusing film according to claim 1 or 2, wherein the plurality of micro light sources in the array light source are arranged so that a distance between centers of adjacent micro light sources is constant.   When the plurality of minute light sources in the array light source connect adjacent minute light sources with line segments, a plurality of squares having one side as the line segment, a plurality of regular triangles having one side as the line segment, or one The method for producing a light diffusing film according to any one of claims 1 to 3, wherein the line segments are arranged so as to be drawn.   In the said arrangement | sequence light source, the distance between centers of adjacent micro light sources is made into the value within the range of 3-25 mm, The manufacturing method of the light-diffusion film as described in any one of Claims 1-4 characterized by the above-mentioned.   The said process (c) WHEREIN: The half angle of the directivity angle of the active energy ray irradiated from the said micro light source is made into the value within the range of 2-50 degrees, It is any one of Claims 1-5 characterized by the above-mentioned. The manufacturing method of the light-diffusion film of description.   The said process (c) WHEREIN: The space | interval of the surface of the said coating layer and the lower end of the said arrangement | sequence light source shall be a value within the range of 5-100 cm, It is any one of Claims 1-6 characterized by the above-mentioned. The manufacturing method of the light-diffusion film of description.   The light according to any one of claims 1 to 7, wherein, in the step (c), the peak wavelength of the active energy ray irradiated from the minute light source is set to a value within a range of 200 to 410 nm. A method for producing a diffusion film.