JP2013210408A - Manufacturing method for anisotropic light diffusion film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for an anisotropic light diffusion film capable of increasing a degree of freedom in effectively controlling a direction at which incident light is diffused anisotropically, as compared to the conventional method using a linear light source.SOLUTION: A manufacturing method for an anisotropic light diffusion film having a louver structure, in which a plurality of plate regions having different refractive indices are alternately arranged on one arbitrary direction along a film surface, includes the following steps (a) to (c): (a) a step for preparing a composition for the anisotropic light diffusion film, the composition including two polymerizable compounds having different refractive indices; (b) a step for coating the composition for the anisotropic light diffusion film on a process sheet and for forming a coating layer; and (c) a step for irradiating the coating layer with active energy beam as parallel light through an isotropic light diffusion element for anisotropically diffusing irradiated light, and for forming the louver structure in which the plate regions are extended in a direction parallel to the light diffusion direction of the anisotropic light diffusion element when viewed from top.

Description

The present invention relates to a method for producing an anisotropic light diffusion film.
In particular, the present invention relates to a method for manufacturing an anisotropic light diffusing film that can effectively increase the degree of freedom in controlling the direction in which incident light is diffused in anisotropic light as compared with the case of using a conventional linear light source.

  Conventionally, for example, in the optical technical field to which a liquid crystal display device or the like belongs, incident light from a specific direction can be diffused in a specific direction, and incident light from other directions can be transmitted straight as it is. The use of isotropic light diffusion films has been proposed.

  Various forms are known as such an anisotropic light diffusing film, and in particular, a louver structure in which a plurality of plate-like regions having different refractive indexes are alternately arranged in any one direction along the film surface. An anisotropic light diffusing film having a wide range is widely used (for example, Patent Documents 1 and 2).

That is, Patent Document 1 discloses a light control plate (anisotropic light diffusion film) that is a plastic sheet and selectively scatters incident light in an angle range of two or more with respect to the sheet. Has been.
In Patent Document 1, a resin composition composed of a plurality of compounds having one or more polymerizable carbon-carbon double bonds in a molecule having a difference in refractive index is maintained in a film shape and specified. A first step of curing the composition by irradiating ultraviolet rays from the direction of the step, and irradiating ultraviolet rays from a direction different from the first step while maintaining the resin composition on the obtained cured product as a film. The manufacturing method of the light control board (anisotropic light-diffusion film) characterized by consisting of the 2nd process hardened and repeating the 2nd process as needed is disclosed.

  Further, in Patent Document 2, as shown in FIG. 21, a photopolymerizable composition containing at least two kinds of compounds each having a polymerizable carbon-carbon bond in the molecule and different in refractive index is predetermined. Maintaining the film-like body 204 having a length and a width of the linear light source 201 and arranging the linear light source 201 so as to face the film-like body 204 so that the major axis direction of the light source extends across the length direction. An irradiation angle limiting means 202 for irradiating a part of the film-like body 204 with light from the light source 201 at a predetermined angle depending on the position in the width direction of the film-like body 204 is disposed between the light source 201 and the film-like body 204. Irradiating light from the light source 201 at a predetermined irradiation angle over the entire length of the film-like body 204 while moving the film-like body 204 relative to the light source 201 and the limiting means 202 in the length direction. Membrane 2 Method for producing a light control plate which selectively scatters light incident at a specific incidence angle comprising curing the 4 (anisotropic light-diffusing film) is disclosed.

JP 63-309902 A (Claims) Japanese Patent Laid-Open No. 2-67501 (Claims)

However, in Patent Documents 1 and 2, when continuously mass-producing anisotropic light diffusing films, while moving the coating layer made of the composition for anisotropic light diffusing film on a conveyor or the like, By irradiating active energy rays using a linear light source, an anisotropic light diffusion film having a predetermined louver structure is produced.
Therefore, in the case of Patent Documents 1 and 2, although it is possible to obtain an anisotropic light diffusion film that diffuses incident light in a direction along the moving direction of the coating layer, the incident light is moved along the moving direction of the coating layer. There was a problem that it was not possible to obtain an anisotropic light diffusing film that diffuses anisotropic light in a direction perpendicular to the above direction.

More specifically, in order to obtain an anisotropic light diffusing film that diffuses incident light in a direction orthogonal to the direction along the direction of movement of the coating layer, in order to obtain an anisotropic light diffusion film in the direction along the direction of movement of the coating layer. It is necessary to form a louver structure composed of extending plate-like regions.
For this reason, when trying to form such a louver structure in Patent Documents 1 and 2, the linear light source is arranged so that the major axis direction of the linear light source is a direction along the moving direction of the coating layer. Become.
However, even if the linear light source is arranged in such a manner, when viewed from the cross section in the moving direction of the coating layer, the active energy rays from the linear light source are irradiated at different angles depending on the position in the width direction on the surface of the coating layer. Therefore, the light diffusion characteristics of the obtained anisotropic light diffusion film become non-uniform.
Therefore, in the cited references 1 and 2, when trying to obtain a long anisotropic light diffusion film that diffuses incident light in a direction orthogonal to the longitudinal direction, first, the film was viewed from above. In some cases, it is necessary to obtain an anisotropic light diffusion film having a louver structure in which plate-like regions are arranged along the width direction. Next, it is necessary to cut them and change the 90 ° direction to connect a plurality of anisotropic light diffusion films. For this reason, the problem that the light diffusibility became non-uniform | heterogenous in the joint part, or the intensity | strength of a film fell easily was seen.
Under such circumstances, there has been a demand for a long anisotropic light diffusing film that can be easily applied to a large screen or the like and does not cause problems such as seams.
That is, not only the conventional anisotropic light diffusion film that diffuses the incident light in the direction along the moving direction of the coating layer, but also the difference that diffuses the incident light in the direction orthogonal to the longitudinal direction. There has been a demand for a manufacturing method that can be manufactured also for an isotropic light diffusing film and that has excellent flexibility in controlling the direction in which incident light is diffused anisotropically.

Accordingly, the inventors of the present invention have made diligent efforts in view of the circumstances as described above, and when forming a louver structure, an anisotropic light diffusing element for diffusing irradiated light to anisotropic light is applied to a coating layer. The present inventors have found that an anisotropic light diffusing film that solves the above-described problems can be obtained by irradiating active energy rays as parallel light through the present invention, thereby completing the present invention.
That is, the object of the present invention is to provide a method for producing an anisotropic light diffusing film that can effectively increase the degree of freedom in controlling the direction in which incident light is anisotropically diffused as compared with the case of using a conventional linear light source. Is to provide.

According to the present invention, there is provided a method for producing an anisotropic light diffusing film having a louver structure in which a plurality of plate-like regions having different refractive indexes are alternately arranged in any one direction along a film surface, which comprises the following steps ( The manufacturing method of the anisotropic light-diffusion film characterized by including a)-(c) is provided, and the problem mentioned above can be solved.
(A) The process of preparing the composition for anisotropic light-diffusion films containing two polymeric compounds from which a refractive index differs (b) The process of apply | coating the composition for anisotropic light-diffusion films with respect to a process sheet, and forming a coating layer (C) When the application layer is irradiated with active energy rays as parallel light via an anisotropic light diffusing element for diffusing the irradiated light with anisotropic light, and viewed from above, the light diffusion direction of the anisotropic light diffusing element Step of forming a louver structure in which a plate-like region extends in a direction parallel to the direction, that is, in the anisotropic light diffusing film manufacturing method of the present invention, when forming the louver structure, irradiation light is applied to the coating layer. Since an active energy ray as parallel light is irradiated through an anisotropic light diffusing element for diffusing anisotropic light, an anisotropic light diffusing film can be produced without using a conventional linear light source. it can.
Therefore, for example, by a simple operation such as rotating the anisotropic light diffusing element, the degree of freedom in controlling the direction in which incident light is anisotropically diffused is effectively increased as compared with the case of using a conventional linear light source. be able to.
In particular, according to the present invention, anisotropic light that diffuses incident light in a direction orthogonal to the direction along the moving direction of the coating layer, which is impossible with a manufacturing method using a conventional linear light source. The diffusion film can also be easily manufactured.

In carrying out the method for producing an anisotropic light diffusing film of the present invention, in step (c), while irradiating irradiation light while moving the coating layer formed on the process sheet, when viewed from above, The acute angle formed by the imaginary line along the moving direction of the coating layer and the light diffusion direction of the anisotropic light diffusing element is preferably set to a value of 80 ° or less.
By carrying out in this way, anisotropic light is incident in a direction perpendicular to or close to the direction along the moving direction of the coating layer, which is impossible with a manufacturing method using a conventional linear light source. An anisotropic light diffusing film that can be diffused can be easily produced.

Moreover, when implementing the manufacturing method of the anisotropic light-diffusion film of this invention, it is preferable to use the lens diffusion plate which has a several micro lens on the surface as an anisotropic light-diffusion element in a process (c).
By carrying out in this way, not only can the louver structure in which the plate-like region extends in a direction parallel to the light diffusion direction of the anisotropic light diffusing element be formed more stably, but also the activity of the anisotropic light diffusing element can be improved. The durability against energy rays can also be effectively improved.

In carrying out the method for producing an anisotropic light diffusing film of the present invention, in the step (c), as the anisotropic light diffusing element, a plurality of plate-like regions having different refractive indexes are alternately arranged in any one direction along the film surface. It is preferable to use an interstitial anisotropic light diffusing film having a louver structure.
By carrying out in this way, the louver structure in which the plate-like region extends in a direction parallel to the light diffusion direction of the anisotropic light diffusing element can be formed more stably.

Moreover, when implementing the manufacturing method of the anisotropic light-diffusion film of this invention, it is preferable to make the parallelism of the active energy ray as parallel light into a value of 10 degrees or less in a process (c).
By carrying out in this way, the louver structure in which the plate-like region extends in a direction parallel to the light diffusion direction of the anisotropic light diffusing element can be formed more stably.

In carrying out the method for producing an anisotropic light diffusing film of the present invention, in the step (c), the peak illuminance of the active energy ray on the surface of the coating layer is set to a value within the range of 0.1 to 50 mW / cm ^2. It is preferable.
By carrying out in this way, a louver structure in which a plate-like region extends in a direction parallel to the light diffusion direction of the anisotropic light diffusing element can be formed more efficiently.
The peak illuminance here means a measured value at a portion where the active energy ray irradiated on the surface of the coating layer shows the maximum value.

Moreover, when implementing the manufacturing method of the anisotropic light-diffusion film of this invention, it is set to the value within the range of 5-300 mJ / cm < ² > in the process (c) in the integrated light quantity of the active energy ray in the surface of a coating layer. preferable.
By carrying out in this way, it is possible to more efficiently form a louver structure in which a plate-like region extends in a direction parallel to the light diffusion direction of the anisotropic light diffusing element.

Moreover, when implementing the manufacturing method of the anisotropic light-diffusion film of this invention, it is preferable to make the moving speed of a coating layer into the value within the range of 0.1-10 m / min in a process (c).
By carrying out in this way, the louver structure in which the plate-like region extends in a direction parallel to the light diffusion direction of the anisotropic light diffusing element can be formed more efficiently.

FIG. 1A to FIG. 1B are diagrams for explaining an outline of a louver structure in an anisotropic light diffusion film. FIGS. 2A to 2B are diagrams for explaining incident angle dependency, anisotropy, and an opening angle in an anisotropic light diffusing film. FIGS. 3A to 3C are diagrams provided to explain the active energy ray irradiation process. FIGS. 4A to 4B are diagrams provided to explain the light diffusion direction of the anisotropic light diffusing element. FIGS. 5A to 5B are diagrams provided to describe a specific example of the anisotropic light diffusing element. FIG. 6 is another diagram provided for explaining the active energy ray irradiation process. FIG. 7 is a diagram for explaining the configuration of an irradiation apparatus for irradiating active energy rays as parallel light. FIGS. 8A and 8B are views provided to explain the louver structure. FIG. 9 is a diagram provided for explaining the configuration of the anisotropic light diffusing film of Example 1. FIG. FIGS. 10A to 10B are photographs provided to explain the state of the cross section of the anisotropic light diffusing film of Example 1. FIG. FIGS. 11A to 11B are a spectrum diagram and a photograph provided for explaining the light diffusion characteristics of the anisotropic light diffusion film of Example 1. FIG. FIG. 12 is a diagram provided for explaining the structure of the anisotropic light diffusion film of Example 2. FIGS. 13A to 13B are photographs provided to explain the state of the cross section of the anisotropic light diffusion film of Example 2. FIG. FIGS. 14A to 14B are a spectrum diagram and a photograph provided for explaining the light diffusion characteristics of the anisotropic light diffusion film of Example 2. FIG. FIG. 15 is a diagram provided for explaining the configuration of the light diffusion film of Comparative Example 1. FIGS. 16A to 16B are photographs for explaining the state of the cross section of the light diffusion film of Comparative Example 1. FIG. FIGS. 17A to 17B are a spectrum diagram and a photograph provided to explain the light diffusion characteristics of the light diffusion film of Comparative Example 1. FIG. FIG. 18 is a diagram provided for explaining the structure of the film of Comparative Example 2. FIGS. 19A to 19B are photographs explaining the state of the cross section of the film of Comparative Example 2. FIG. 20A to 20B are a spectrum diagram and a photograph provided to explain the light diffusion characteristics of the film of Comparative Example 2. FIG. 21 is a diagram for explaining a method for producing an anisotropic light diffusion film using a conventional linear light source.

An embodiment of the present invention is a method for producing an anisotropic light diffusing film having a louver structure in which a plurality of plate-like regions having different refractive indexes are alternately arranged in any one direction along a film surface, and includes the following steps: It is a manufacturing method of the anisotropic light-diffusion film characterized by including (a)-(c).
(A) The process of preparing the composition for anisotropic light-diffusion films containing two polymeric compounds from which a refractive index differs (b) The process of apply | coating the composition for anisotropic light-diffusion films with respect to a process sheet, and forming a coating layer (C) When the application layer is irradiated with active energy rays as parallel light via an anisotropic light diffusing element for diffusing the irradiated light with anisotropic light, and viewed from above, the light diffusion direction of the anisotropic light diffusing element Of forming a louver structure in which a plate-like region extends in a direction parallel to the following, embodiments of the present invention will be specifically described with reference to the drawings as appropriate, in order to facilitate understanding of the description First, the basic principle of light diffusion in the anisotropic light diffusion film will be described.

1. Basic Principle of Light Diffusion in Anisotropic Light Diffusing Film First, the basic principle of light diffusion in an anisotropic light diffusing film will be described with reference to FIGS.
First, FIG. 1A shows a top view (plan view) of the anisotropic light diffusing film 10, and FIG. 1B shows the anisotropic light diffusing film 10 shown in FIG. A cross-sectional view of the anisotropic light diffusing film 10 when cut in the vertical direction along A-A and viewing the cut surface from the arrow direction is shown.
2A shows an overall view of the anisotropic light diffusion film 10, and FIG. 2B shows a cross-sectional view of the anisotropic light diffusion film 10 of FIG. 2A viewed from the X direction. Indicates.
As shown in the plan view of FIG. 1A, the anisotropic light diffusion film 10 has a relatively high refractive index and a relatively high refractive index in a given direction along the film surface. Is provided with a louver structure 13 in which plate-like regions 14 having a low height are alternately arranged in parallel.
In other words, when the film is placed on a horizontal plane, it has a louver structure consisting of a plate-like region extending horizontally in the film.
In addition, as shown in the cross-sectional view of FIG. 1B, the relatively high refractive index plate-like region 12 and the relatively low refractive index plate-like region 14 each have a predetermined thickness. In the normal direction (film thickness direction) of the anisotropic light diffusion film 10, 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 anisotropic light-diffusion film 10. FIG.
That is, as shown in FIG. 1B, the incident angle of incident light on the anisotropic light diffusing film 10 is a value within a predetermined angle range from parallel to the boundary surface 13 ′ of the louver structure 13, that is, light diffusing incident. When the value is in the angle region, the incident light (52, 54) passes along the film thickness direction while changing the direction inside the relatively high refractive index plate-like region 12 in the louver structure. By passing through, it is presumed that the traveling direction of light on the light exit surface side is not uniform.
As a result, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused by the anisotropic light diffusion film 10 (52 ', 54').
On the other hand, when the incident angle of the incident light with respect to the anisotropic light diffusion film 10 deviates from the light diffusion incident angle region, the incident light 56 is diffused by the anisotropic light diffusion film as shown in FIG. However, it is estimated that the light passes through the anisotropic light diffusion film 10 as it is (56 ').
In the present invention, “light diffusion incident angle region” means incident light corresponding to emitting diffused light when the angle of incident light from a point light source is changed with respect to the anisotropic light diffusing film. Means the angle range.
In addition, as shown in FIG. 2A, the “light diffusing incident angle region” is an angle determined for each anisotropic light diffusing film depending on a refractive index difference or an inclination angle of the louver structure in the anisotropic light diffusing film. It is an area.

Based on the above basic principle, the anisotropic light diffusion film 10 provided with the louver structure 13 can exhibit incident angle dependency in light transmission and diffusion as shown in FIG. 2A, for example.
In addition, the anisotropic light diffusion film of the present invention is characterized by having “anisotropy”. In the present invention, “anisotropy” means that the incident light is a film as shown in FIG. When the light is diffused by the diffused light, the diffused light (diffused light shape) in the plane parallel to the film has different properties depending on the direction in the same plane. means.
More specifically, as shown in FIG. 2 (a), the component perpendicular to the direction of the louver structure extending along one arbitrary direction along the film surface is selected from the components included in the incident light. On the other hand, light diffusion occurs on the other hand, among the components included in the incident light, light diffusion is difficult to occur for components parallel to the direction of the louver structure extending along any one direction along the film surface, Anisotropic light diffusion is realized.
Therefore, the shape of the spread of the diffused light in the anisotropic light diffusing film is substantially elliptical as shown in FIG.

Further, as described above, the incident light component contributing to the anisotropic light diffusion is a component perpendicular to the direction of the louver structure mainly extending along any one direction along the film surface. As shown in b), in the present invention, the “incident angle θ1” of incident light means the incident angle of a component perpendicular to the direction of the louver structure extending along one arbitrary direction along the film surface. It shall be. Further, at this time, the incident angle θ1 means an angle (°) when the angle with respect to the normal to the incident side surface of the anisotropic light diffusing film is 0 °.
In the present invention, “light diffusion angle region” means an angle range of diffused light obtained in this state by fixing a point light source at an angle at which incident light is most diffused with respect to an anisotropic light diffusion film. It shall be.
Furthermore, in the present invention, the “diffuse light opening angle” is the width of the “light diffusion angle region” described above, and, as shown in FIG. 2B, along any one direction along the film surface. The opening angle θ2 of the diffused light when the cross section of the film is viewed from the direction X parallel to the direction of the extending louver structure is meant.

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

2. Step (a): Preparation Step for Composition for Anisotropic Light Diffusion Film Step (a) is a step for preparing a predetermined composition for anisotropic 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 optionally added to the mixed solution, and then further diluted with a diluent solvent as necessary so as to obtain a desired viscosity while stirring until uniform. It is preferable to obtain a solution of the composition for anisotropic 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, a polymerizable compound having a relatively high refractive index (hereinafter sometimes referred to as component (A)). Type) is not particularly limited, but the main component is preferably a (meth) acrylic acid ester containing a plurality of aromatic rings.
The reason for this is that by including a specific (meth) acrylic acid ester as the component (A), the polymerization rate of the component (A) is changed to a polymerizable compound having a relatively low refractive index (hereinafter referred to as (B). It is presumed that the polymerization rate between these components can be effectively reduced by making the polymerization rate faster than the polymerization rate of the component)) It is to be done.
As a result, when photocured, a so-called louver structure in which the plate-like regions derived from the component (A) and the plate-like regions derived from the component (B) extend alternately can be formed efficiently. .
In addition, by including a specific (meth) acrylic acid ester as the component (A), the monomer stage has sufficient compatibility with the component (B), but a plurality of stages in the polymerization process. Then, it is presumed that the louver structure can be formed more efficiently by reducing the compatibility with the component (B) to a predetermined range.
Furthermore, by including a specific (meth) acrylic acid ester as the component (A), the refractive index of the plate-like region derived from the component (A) in the louver structure is increased, and the plate derived from the component (B) The difference from the refractive index of the 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), a louver structure in which plate-like regions having different refractive indexes are alternately extended in combination with the characteristics of the component (B) described later is provided. An anisotropic light diffusion film 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 aromatic Examples thereof include those in which a part of hydrogen atoms on the ring are substituted by halogen, alkyl, alkoxy, halogenated alkyl or the like.

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

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

(In the general formula (2), R ¹¹ is a hydrogen atom or a methyl group, the carbon number n is an integer of 1 to 4, and the repeating 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.
In addition, the refractive index of the plate-like region derived from the component (A) in the louver structure is increased, and the difference from the refractive index of the plate-like region derived from the component (B) can be more easily set to a predetermined value or more. Can be adjusted.

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 plate-like region derived from the component (A) becomes too low. This is because it may be difficult to efficiently form the structure.
Therefore, when R ^{1 to} R ¹⁰ in the general formula (1) include any of an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, and a carboxyalkyl group, the number of carbon atoms in the alkyl portion is determined. A value in the range of 1 to 3 is more preferable, and a value in the range of 1 to 2 is more preferable.

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

Moreover, it is preferable that any one of R < ² > -R < ⁹ > in General formula (1) is a substituent represented by General formula (2).
This is because, by setting the position of the substituent represented by the general formula (2) to a position other than R ¹ and R ¹⁰ , the components (A) are oriented and crystallized in the stage before photocuring. This is because it can be effectively prevented.
Further, 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.
As a result, in the photocuring stage, it is possible to aggregate and phase separate the component (A) and the component (B) at a fine level, and to obtain an anisotropic light diffusion film having a louver structure more efficiently. This is because it can.
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, it is possible to more efficiently form a louver structure in which plate-like regions derived from the component (A) and plate-like regions derived from the component (B) extend alternately when photocured. .
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 the louver structure.
Therefore, the molecular weight of the component (A) is more preferably set to a value within the range of 240 to 1,500, and further preferably set to a value within the range of 260 to 1,000.
The molecular weight of component (A) can be determined from the calculated value obtained from the molecular composition and the atomic weight of the constituent atoms, and can also be measured as a weight average molecular weight using gel permeation chromatography (GPC). .

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

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

(1) -5 Content Further, the content of the component (A) in the composition for anisotropic light diffusing film is set to 100 parts by weight of the component (B) which is a polymerizable compound having a relatively low refractive index described later. Thus, the value is preferably in the range of 25 to 400 parts by weight.
The reason for this is that when the content of the component (A) is less than 25 parts by weight, the ratio of the component (A) to the component (B) decreases, and the width of the plate-like region derived from the component (A) However, this is because the width of the plate-like region derived from the component (B) is excessively small, and it may be difficult to obtain a louver structure having good incident angle dependency. Moreover, it is because the length of the louver in the thickness direction of the anisotropic light diffusing film becomes insufficient and the light diffusibility may not be exhibited. 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 plate-like region derived from the component (A) increases. This is because the width of the plate-like region derived from the component (B) becomes excessively large, and on the contrary, it may be difficult to obtain a louver structure having good incident angle dependency. Moreover, it is because the length of the louver in the thickness direction of the anisotropic light diffusing film becomes insufficient and the light diffusibility may not be exhibited.
Therefore, the content of the component (A) is more preferably set to a value in the range of 40 to 300 parts by weight with respect to 100 parts by weight of the component (B), and a value in the range of 50 to 200 parts by weight. More preferably.

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

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

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

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

Among the components that form urethane (meth) acrylate, examples of the polyalkylene glycol that is the component (B2) 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 will become a favorable soft segment in the said hardened | cured material, and it can improve the handling property and mounting property of an anisotropic light-diffusion film effectively. It is.
The weight average molecular weight of the component (B) can be adjusted mainly by the weight average molecular weight of the component (B2). Here, the weight average molecular weight of (B2) component is 2,300-19,500 normally, Preferably it is 4,300-14,300, Most preferably, it is 6,300-12,300.

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

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

(2) -2 Weight average molecular weight Moreover, it is preferable to make the weight average molecular weight of (B) component into the value within the range of 3,000-20,000.
This is because, by setting the weight average molecular weight of the component (B) within a predetermined range, a predetermined difference is caused in the polymerization rate of the component (A) and the component (B), and the copolymerizability of both components is effectively improved. This is because it can be lowered.
As a result, when photocured, a louver structure in which plate-like regions derived from the component (A) and plate-like regions derived from the component (B) extend alternately can be efficiently 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 louver structure. On the other hand, when the weight average molecular weight of component (B) exceeds 20,000, it is difficult to form a louver structure in which plate-like regions derived from component (A) and component (B) extend alternately. This is because the compatibility with the component (A) may be excessively decreased, and 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 Single use Moreover, although (B) component may use together 2 or more types from which molecular structure and a weight average molecular weight differ, the refractive index of the plate-shaped area | region derived from (B) component in a louver structure From the viewpoint of suppressing variations in the number, only one type is preferably used.
That is, when a plurality of (B) components are used, the refractive index in the plate-like region where the refractive index derived from the (B) component is relatively low varies or increases, and the refraction derived from the (A) component. This is because the difference in refractive index from the plate-like region having a relatively high rate may become non-uniform or excessively decrease.

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

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

(2) -5 Content The content of the component (B) in the anisotropic light diffusing film composition is in the range of 10 to 80% by weight with respect to 100% by weight of the total amount of the anisotropic light diffusing film composition. It is preferable to set the value within the range.
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 width of the plate-like region derived from the component (B) However, this is because the width of the plate-like region derived from the component (A) is excessively small, and it may be difficult to obtain a louver structure having good incident angle dependency. Moreover, it is because the length of the louver in the thickness direction of the anisotropic 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 plate-like region derived from the component (B) increases. This is because the width of the plate-like region derived from the component (A) is excessively large and, on the contrary, it may be difficult to obtain a louver structure having good incident angle dependency. Moreover, it is because the length of the louver in the thickness direction of the anisotropic 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 anisotropic light-diffusion films, and 30 to 60 weight% It is more preferable to set the value within the range.

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

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

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

3. Step (b): Application Step The step (b) is a step of forming the coating layer 1 by applying the prepared composition for anisotropic light diffusion film to the step sheet 2 as shown in FIG. It is.
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 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 anisotropic light diffusion film in the process sheet in order to facilitate peeling of the obtained anisotropic light diffusion film from the process sheet after photocuring. It is preferable to provide it.
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 the process sheet is usually a value within a range of 25 to 200 μm.

Examples of the method for applying the anisotropic light diffusion 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. It can be done by a method.
At this time, the thickness of the coating layer is preferably set to a value in the range of 100 to 700 μm.

4). Step (c): Active energy ray irradiation step In step (c), for example, as shown in FIG. The louver structure 13a is formed by extending plate-like regions (12a, 14a) in a direction parallel to the light diffusion direction K1 of the anisotropic light diffusing element 60 when irradiated with active energy rays 50 as parallel light and viewed from above. Is a step of forming.

That is, the active energy ray 50 as parallel light emitted from the irradiation device 80 is selectively diffused with respect to the light diffusion direction K1 of the anisotropic light diffusing element 60 through the anisotropic light diffusing element 60. become.
Therefore, the surface of the coating layer 1 is irradiated with the anisotropic active energy ray 50a ′ selectively diffused in the light diffusion direction K1 of the anisotropic light diffusing element 60.
As a result, the component (A) and the component (B) having different refractive indexes contained in the coating layer 1 alternate plate-like regions (12a, 14a) extending in the direction along the anisotropy of the active energy ray 50a ′. Thus, the louver structure 13a is formed.
As a result, when viewed from above, the louver structure 13 in which the plate-like regions (12a, 14a) extend in a direction parallel to the light diffusion direction K1 of the anisotropic light diffusing element 60 is formed.

In addition, for example, as shown in FIG. 3C, the anisotropic light diffusing element 60 is rotated 90 ° in the same plane and arranged to rotate the light diffusing direction by 90 ° from K1 to K2. it can.
Thereby, a louver structure 13b composed of plate-like regions (12b, 14b) arranged in a direction parallel to the light diffusion direction K2, that is, in a direction orthogonal to the arrangement direction of the louver structure 13a in FIG. 3B is formed. Will be.
In other words, the present embodiment has a feature that the arrangement direction of the louver structure 13 of the anisotropic light diffusion film 10 can be freely designed only by adjusting the arrangement direction of the anisotropic light diffusion element 60, that is, the light diffusion direction K. .

The anisotropic light diffusing element 60 in the present invention means a light diffusing element capable of diffusing incident light with anisotropic light.
That is, as shown in FIG. 4A, it means a light diffusing element that diffuses incident light in a predetermined direction K and does not substantially diffuse in a direction H orthogonal thereto.
Therefore, the shape of the spread of the diffused light in the anisotropic light diffusing element is substantially elliptical as shown in FIG.
Further, the “light diffusion direction” of the anisotropic light diffusing element is the direction K in the case of FIG.
Further, as the degree of anisotropy of the anisotropic light diffusing element 60, it is preferable to set the half-value angle θk of the light diffusion angle in the light diffusion direction K to a value within the range of 10 to 180 °, and 30 to 90 °. A value within the range is more preferable.
Further, the half-value angle θh of the light diffusion angle in the non-light diffusion direction H is preferably set to a value within the range of 0 to 10 °, and more preferably set to a value within the range of 0 to 5 °.
As shown in FIG. 4B, the half-value angle of the light diffusion angle is obtained when the horizontal axis represents the light diffusion angle (°) of the diffused light and the vertical axis represents the relative intensity (−) of the diffused light. Further, it means a light diffusion angle (°) at which the relative intensity is 0.5.

Further, the type of the anisotropic light diffusing element is not limited at all. For example, it is preferable to use a lens diffusing plate 60a having a plurality of microlenses on the surface as shown in FIG.
This is because, with such a lens diffusing plate, it is possible not only to form a louver structure in which a plate-like region extends in a direction parallel to the light diffusing direction, but also to form an anisotropic light diffusing element. This is because the durability against the active energy ray can be effectively improved.
That is, for example, as shown in FIG. 5A, if the lens diffuser plate 60a is formed of irregularities having regularity and has a plurality of microlenses on the surface, the half-value angle of the light diffusion angle in the light diffusion direction. This is because the half-value angle θh of the light diffusion angle in the non-light diffusion direction can be effectively narrowed while effectively extending θk, and excellent anisotropic light diffusion can be exhibited.
FIG. 5A shows a general lens diffuser plate with θh ≠ 0 °. However, for example, a lens diffuser plate with θh = 0 ° theoretically such as a lenticular lens is used. It may be used.
As a raw material for the lens diffusion plate, it is preferable to use a synthetic resin such as an acrylic resin, a polystyrene resin or a polycarbonate resin, or a glass having a higher weather resistance because of excellent transparency and weather resistance.

Further, as shown in FIG. 5B, the anisotropic light diffusing element 60 has an louver structure in which a plurality of plate-like regions having different refractive indexes are alternately arranged in any one direction along the film surface. It is also preferable to use the anisotropic light diffusion film 60b for use.
The reason for this is that an interstitial anisotropic light diffusion film can precisely control the direction of diffused light and has high uniformity of brightness of the diffused light, so that the plate-like region extends in a direction parallel to the light diffusion direction. This is because the louver structure can be formed more stably.

Further, as shown in FIGS. 3B to 3C, the irradiation light is irradiated while moving the coating layer 1 formed on the process sheet 2, and it is shown in FIG. 6 when viewed from above. Thus, it is preferable that the acute angle θ3 formed by the virtual line E ′ along the moving direction E of the coating layer 1 and the light diffusion direction K of the anisotropic light diffusing element 60 is set to a value of 80 ° or less.
The reason for this is that, by carrying out in this way, anisotropic light is incident in a direction perpendicular to or close to the moving direction of the coating layer, which is impossible with a manufacturing method using a conventional linear light source. This is because an anisotropic light diffusing film that can be diffused can be easily produced.
That is, when θ3 exceeds 80 °, it is difficult to diffuse the incident light in the direction orthogonal to or in the direction perpendicular to the moving direction E of the coating layer 1 in the obtained anisotropic light diffusion film 10. This is because it may become.
Therefore, the acute angle θ3 formed by the imaginary line E ′ along the moving direction E of the coating layer 1 and the light diffusion direction K of the anisotropic light diffusing element 60 is more preferably set to a value of 45 ° or less. More preferably, the value of

In addition, the parallelism of the active energy rays as parallel light is preferably set to a value of 10 ° or less.
This is because the louver structure in which the plate-like region extends in a direction parallel to the light diffusion direction of the anisotropic light diffusing element is obtained by setting the parallelism of the active energy rays as parallel light to a value within this range. It is because it can form stably.
That is, when the parallelism exceeds 10 °, the half-value angle θh of the light diffusion angle in the non-light diffusion direction H of the anisotropic light diffusion element 60 described with reference to FIGS. This is because the anisotropy of the irradiated light may be excessively reduced.
Therefore, the parallelism of the parallel light is more preferably set to a value of 5 ° or less, and further preferably set to a value of 2 ° or less.

Here, as an example of an apparatus for obtaining parallel light having the above-described parallelism, an irradiation apparatus 80 for irradiating active energy rays as parallel light will be described with reference to FIG.
In other words, the irradiation device 80 sequentially moves the active energy rays emitted from the light source 82 such as a short arc Hg lamp in order of the microlens array 84a, the rod lens 84b, and other lenses (84c to 84e). It is an apparatus that can be adjusted by passing through and can finally produce parallel light with a high degree of parallelism.
In addition, the irradiation apparatus in this invention is not limited to this.
For example, as disclosed in Japanese Patent Application Laid-Open No. 2005-292219 and Japanese Patent Application Laid-Open No. 2009-173018, an aggregate of cylindrical objects is interposed directly under a linear light source, and active energy rays are irradiated through the aggregate of cylindrical objects. As long as the parallelism of the parallel light is within the above-described range, such as an irradiation device of the type that performs the above, it can be suitably used.

Moreover, it is preferable to make the peak illumination intensity of the active energy ray in the surface of a coating layer into the value within the range of 0.1-50 mW / cm < ² >.
This is because the louver structure in which the plate-like region extends in a direction parallel to the light diffusion direction of the anisotropic light diffusing element by setting the peak illuminance of the active energy ray on the surface of the coating layer to a value within such a range, It is because it can form more efficiently.
That is, when the peak illuminance is less than 0.1 mW / cm ² , it may be difficult to clearly form the louver structure. On the other hand, when the peak illuminance is a value exceeding 50 mW / cm ² , it is estimated that the curing rate becomes too fast, and the louver structure may not be clearly formed.
Therefore, it is more preferably a value within a range the surface of the active energy ray 0.3~10mW / cm ² the peak irradiance of the coating layer, to a value within the range of 0.5~5mW / cm ² Is more preferable.
The peak illuminance here means a measured value at a portion where the active energy ray irradiated on the surface of the coating layer shows the maximum value.

Moreover, it is preferable to make the integrated light quantity of the active energy ray in the surface of a coating layer into the value within the range of 5-300 mJ / cm < ² >.
This is because the louver structure in which the plate-like region extends in a direction parallel to the light diffusion direction of the anisotropic light diffusing element by setting the integrated light amount of the active energy ray on the surface of the coating layer to a value within such a range, This is because it can be formed more efficiently.
That is, when the integrated light quantity is less than 5 mJ / cm ² , it may be difficult to sufficiently extend the louver structure from the top to the bottom. On the other hand, when the integrated light amount exceeds 300 mJ / cm ² , coloring may occur in the obtained anisotropic light diffusion film.
Therefore, it is more preferably a value within a range the surface of 10~200mJ / cm ² the integrated light quantity of the active energy ray in the coating layer, more preferably to a value within the range of 15~150mJ / cm ^2.

Moreover, when irradiating an active energy ray, moving a coating layer, it is preferable to make the moving speed of a coating layer into the value within the range of 0.1-10 m / min.
The reason is that the louver structure in which the plate-like region extends in a direction parallel to the light diffusion direction of the anisotropic light diffusing element is formed more efficiently by setting the moving speed of the coating layer within the range. This is because it can be done.
That is, when the moving speed of the coating layer becomes a value of less than 0.1 m / min, productivity may be excessively lowered. On the other hand, when the moving speed of the coating layer exceeds 10 m / min, the coating layer is hardened, in other words, faster than the formation of the louver structure, and the incident angle of the active energy rays with respect to the coating layer changes. This is because the structure may be insufficiently formed.
Therefore, the moving speed of the coating layer is more preferably set to a value within the range of 0.2 to 5 m / min, and further preferably set to a value within the range of 0.3 to 3 m / min.

Further, the distance between the lower end of the irradiation device for emitting active energy rays as parallel light and the upper end of the anisotropic light diffusing element is not particularly limited, but is usually a value within a range of 0 to 500 cm. It is preferable that the value is within the range of 1 to 100 cm.
Further, the distance between the lower end of the anisotropic light diffusing element and the surface of the coating layer is not particularly limited, but it is usually preferably a value within the range of 0.1 to 500 cm, and preferably 1 to 100 cm. A value within the range is preferable.
3 (b) to 3 (c), an anisotropic light diffusing element is interposed in parallel with respect to the coating layer 1 placed horizontally, and active energy rays as parallel light are applied to the coating layer. 1 and the irradiation from the direction orthogonal to the surface of the anisotropic light diffusing element, the embodiment of the present invention is not limited to this.
Therefore, for example, the anisotropic light diffusing element may be inclined and interposed, or the active energy rays as parallel light may be irradiated from an oblique direction.

In the step (c), it is also preferable to irradiate the upper surface of the coating layer with the active energy ray in a state where the active energy ray transmitting sheet is laminated.
The reason for this is that by laminating the active energy ray transmissive sheet, the influence of oxygen inhibition can be effectively suppressed and the louver 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.
Further, the active energy ray transmitting sheet protects the surface of the anisotropic light diffusing film until the anisotropic light diffusing film is used, and is removed during use.
Further, by using the optical member as an active energy ray transmitting sheet, it can be used as it is as a laminate with an anisotropic light diffusion film without being removed even after production.
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, it is also preferable to further irradiate the active energy ray separately from the irradiation of the active energy ray as the step (c) so that the coating layer has a sufficient amount of curing.
Since the active energy ray at this time is intended to sufficiently cure the coating layer, it is preferable to use random light in any traveling direction instead of parallel light.
Moreover, the anisotropic light-diffusion film after an active energy ray irradiation process will be in the state which can be finally used by peeling a process sheet | seat.

5. Anisotropic light diffusing film Hereinafter, the anisotropic light diffusing film obtained by the production method of the present invention will be described.

(1) Louver structure (1) -1 Refractive index In the louver structure, a difference in refractive index between plate-like regions having different refractive indexes, that is, a refractive index of a plate-like region having a relatively high refractive index, The difference from the refractive index of the plate-like region having a low refractive index is preferably set to a value of 0.01 or more.
This is because, by setting the difference in refractive index to a value of 0.01 or more, incident light is stably reflected in the louver structure, and the incident angle dependency derived from the louver structure is further improved. This is because it can.
More specifically, when the difference in refractive index is less than 0.01, the angle range at which incident light is totally reflected in the louver structure is narrowed, and the incident angle dependency may be excessively reduced. Because there is.
Therefore, the difference in the refractive index between the plate-like regions having different refractive indexes in the louver structure is more preferably 0.05 or more, and further preferably 0.1 or more.
The larger the difference between the refractive index of the high refractive index plate-like region and the refractive index of the low refractive index plate-like region, the better. However, from the viewpoint of selecting a material capable of forming a louver structure, about 0.3 is the upper limit. It is thought that.

In the louver structure, the refractive index of the plate-like region having a relatively high refractive index is preferably set to a value in the range of 1.5 to 1.7.
The reason for this is that when the refractive index of the high refractive index plate-like region is less than 1.5, the difference from the low refractive index plate-like region becomes too small, making it difficult to obtain a desired louver structure. Because there is. On the other hand, when the refractive index of the high refractive index plate-shaped region exceeds 1.7, the compatibility between the material substances in the anisotropic light diffusion film composition may be excessively lowered.
Therefore, the refractive index of the high refractive index plate-like region in the louver 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 plate-shaped area | region can be measured according to JISK0062, for example.

In the louver structure, the refractive index of the plate-like region having a relatively low refractive index 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 plate-like 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 plate-like region exceeds 1.5, the difference from the refractive index of the high refractive index plate-like region becomes too small, and it is difficult to obtain a desired louver structure. This is because it may become.
Therefore, the refractive index of the low refractive index plate-like region in the louver 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 plate-shaped area | region can be measured according to JISK0062, for example.

(1) -2 Width As shown in FIG. 8A, the widths (S1, S2) of the high refractive index plate-like region 12 and the low refractive index plate-like region 14 having different refractive indexes in the louver structure 13 are set. These values are each preferably in the range of 0.1 to 15 μm.
This is because the incident light depends on the incident angle derived from the louver structure by reflecting the incident light more stably in the louver structure by setting the width of these plate-like regions to a value in the range of 0.1 to 15 μm. This is because the property can be improved more effectively.
That is, if the width of the plate-like region is a value 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 exceeds 15 μm, the light traveling straight through the louver structure increases, and the uniformity of the diffused light may deteriorate.
Accordingly, in the louver structure, the width of the plate-like regions having different refractive indexes is more preferably set to a value within the range of 0.5 to 10 μm, and further preferably set to a value within the range of 1 to 5 μm.
In addition, the width | variety, length, etc. of the plate-shaped area | region which comprises a louver can be measured by observing a film cross section with an optical digital microscope.

(1) -3 Inclination angle Moreover, as shown to Fig.8 (a), in a louver structure, the several high refractive index plate-shaped area | region 12 and the several low refractive index plate-shaped area | region 14 from which a refractive index differs are film thickness. It is preferable that they are arranged in parallel with each other at a constant inclination angle θa.
The reason is that by making each inclination angle θa of the plate-like region constant, incident light is more stably reflected in the louver structure, and the incident angle dependency derived from the louver structure is further improved. This is because it can.
Θa is a plate when the angle with respect to the normal of the film surface measured in a cross section when the film is cut in a plane perpendicular to the louver structure extending in one direction along the film surface is 0 ° Means the angle of inclination (°).
More specifically, as shown in FIG. 8 (a), it means the angle on the narrow side of the angle formed between the normal line of the upper end surface of the louver structure and the uppermost part of the plate-like region. As shown in FIG. 8A, the inclination angle when the plate-like region is inclined to the right is used as a reference, and the inclination angle when the plate-like region is inclined to the left is expressed as minus.

Moreover, as shown in FIG.8 (b), it is also preferable that the plate-shaped area | regions (12, 14) from which the refractive index in a louver structure differs curves from upper direction to the downward direction along the film thickness direction.
This is because the plate-like region is curved, so that the balance between reflection and transmission in the louver structure can be complicated, and the opening angle of the diffused light can be effectively expanded.
In addition, it is thought that such a curved louver structure is obtained by delaying the polymerization reaction rate by ultraviolet rays in the thickness direction of the coating film.
Specifically, it can be formed by suppressing the illuminance of ultraviolet rays emitted from a parallel light source and moving the applied coating film at a low speed.

(1) -4 Thickness Further, the thickness of the louver structure, that is, the length L1 of the louver structure existing portion in the normal direction of the film surface shown in FIGS. 8A to 8B is in the range of 50 to 500 μm. It is preferable to set the value of.
The reason for this is that by setting the louver structure thickness to a value within this range, the length of the louver structure along the film thickness direction can be secured stably, and incident light can be more stably transmitted within the louver structure. This is because it is possible to further improve the uniformity of the intensity of the diffused light within the light diffusion angle region derived from the louver structure.
That is, when the thickness L1 of the louver structure is less than 50 μm, the length of the louver structure is insufficient, and the incident light that goes straight through the louver structure increases, and the diffused light in the light diffusion angle region is increased. This is because it may be difficult to obtain strength uniformity. On the other hand, when the thickness L1 of the louver structure exceeds 500 μm, when the louver structure is formed by irradiating the composition for anisotropic light diffusion film with active energy rays, the louver structure formed in the initial stage This is because the traveling direction of photopolymerization may diffuse due to the above, and it may be difficult to form a desired louver structure.
Therefore, the thickness L1 of the louver structure is more preferably set to a value within the range of 70 to 300 μm, and further preferably set to a value within the range of 80 to 200 μm.

(2) Film thickness Moreover, it is preferable to make the film thickness of an anisotropic light-diffusion film into the value within the range of 100-500 micrometers.
The reason for this is that by setting the thickness of the anisotropic light diffusing film to a value within this range, even if the anisotropic light diffusing film is used as it is without being laminated, it has excellent light diffusing characteristics. It is because it can exhibit.
That is, when the film thickness is less than 100 μm, the thickness of the louver structure in the film thickness direction formed in the film becomes excessively short, and the incident light that goes straight through the louver structure increases. This is because it may be difficult to obtain a large incident angle dependency. On the other hand, when the film thickness exceeds 500 μm, the irradiation light is irradiated for a long time, so that the mass productivity is excessively reduced or the irradiation light is diffused by the louver structure formed in the initial stage. This is because it may be difficult to form a desired louver structure.
Therefore, the thickness of the anisotropic light diffusion film is more preferably set to a value within the range of 130 to 300 μm, and further preferably set to a value within the range of 150 to 250 μm.
In the thickness direction of the anisotropic light diffusion film, for example, there may be a portion where the louver structure does not exist in the surface layer portion or the like.
Therefore, the thickness of the anisotropic light diffusion film is equal to or greater than the thickness L1 of the louver structure.

(3) Shape of film Although the shape of the anisotropic light diffusion film of the present invention is not limited at all, the length in the short direction of the film may be set to a value within the range of 0.1 to 3 m. Preferably, the value is in the range of 0.5 to 2 m.
On the other hand, the length in the longitudinal direction is not particularly limited.
That is, according to the manufacturing method of the present invention, even an anisotropic light diffusion film that diffuses incident light in a direction orthogonal to the longitudinal direction of the film can be continuously manufactured. is there.
Therefore, the length in the longitudinal direction is preferably 3 m or more, and more preferably 15 m or more.
The reason for this is that, in particular, in the method for producing an anisotropic light diffusing film of the present invention, incident light is diffused in a direction perpendicular to the longitudinal direction according to the embodiment shown in FIG. This is because a long anisotropic light diffusion film having a large area can be easily produced.
By the way, as described in the background art, a long anisotropic light diffusion film having such light diffusion characteristics cannot be obtained by a manufacturing method using a conventional linear light source.
Therefore, conventionally, when an elongated anisotropic light diffusion film having the above-described light diffusion characteristics is to be obtained, a plurality of anisotropic light diffusion films that diffuse anisotropic light in a direction parallel to the longitudinal direction of the incident light are provided. It was necessary to manufacture and rotate it 90 °, then lay it side by side and connect them together.
In this case, problems such as non-uniform light diffusibility at the seam and a tendency for the strength of the film to be easily reduced are observed.
In this respect, if the method for producing an anisotropic light diffusing film of the present invention, a long anisotropic light diffusing film that fundamentally solves the above-described problems can be easily obtained.
In addition, a large-area long anisotropic light diffusion film that diffuses incident light in a direction orthogonal to the longitudinal direction of the incident light is, for example, in a large-area projection screen, the light from the Fresnel lens is vertically directed. It is very important in applications where it diffuses into the surface.

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

[Example 1]
1. Synthesis of low refractive index polymerizable compound (B) component In a container, 1 mol of polypropylene glycol (PPG) having a weight average molecular weight of 9,200 as component (B2) is isophorone diisocyanate as component (B1). After 2 mol of (IPDI) and 2 mol of 2-hydroxyethyl methacrylate (HEMA) as component (B3) were accommodated, polymerization was performed according to a conventional method to obtain a polyether urethane methacrylate having a weight average molecular weight of 9,900.

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

2. Preparation of composition for anisotropic light diffusing film Next, 100 parts by weight of polyether urethane methacrylate having a weight average molecular weight of 9,900 as the component (B) thus obtained is represented by the following formula (3) as the component (A). O-phenylphenoxyethoxyethyl acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A-LEN-10) having a weight average molecular weight of 268, and 2-hydroxy-2-methylpropio as the component (C) After adding 5 parts by weight of phenone, the mixture was heated and mixed at 80 ° C. to obtain a composition for anisotropic light diffusion film.
The refractive indexes of the components (A) and (B) were measured according to JIS K0062 using an Abbe refractometer (Atago Co., Ltd., Abbe refractometer DR-M2, Na light source, wavelength 589 nm). , 1.58 and 1.46, respectively.

3. Application of Composition for Anisotropic Light Diffusing Film Next, the obtained composition for anisotropic light diffusing film was applied to a film-like transparent polyethylene terephthalate film (hereinafter referred to as PET) as process sheet 2 using an applicator. And a coating layer having a thickness of 200 μm was obtained.

4). Next, as shown in FIG. 3B, the irradiation device is arranged so that the irradiation lens is positioned above the obtained coating layer 1 at a distance of 160 mm from the surface of the coating layer 1. A parallel light exposure apparatus (parallelism: 3 °, irradiation area: 7 cm × 7 cm) as 80 was fixed.
In addition, a lens diffusion plate as an anisotropic diffusing element 60 (manufactured by Optical Solutions Co., Ltd., LSD40 × 0) is provided so that the lower surface thereof is positioned above the coating layer at a distance of 50 mm from the surface of the coating layer. .2PC10-F12, material: polycarbonate, thickness: 254 μm, half-value angle θk of light diffusion angle in light diffusion direction: 40 °, half-value angle θh of light diffusion angle in non-light diffusion direction: 0.2 ° .
Next, in FIG. 6, when the obtained coating layer 1 is viewed from above, a virtual line E ′ along the moving direction of the coating layer 1 and the light diffusion direction K of the anisotropic light diffusing element 60 are formed. While moving parallel at a speed of 0.32 m / min using a conveyor so that the acute angle θ3 becomes 0 °, the ultraviolet rays are irradiated, the length in the long direction (the moving direction of the coating layer) is 3 m, and the short direction A long anisotropic light diffusion film having a length of 0.07 m and a film thickness of 200 μm was obtained.
At this time, the peak illuminance on the surface of the coating layer was 1.92 mW / cm ² , and the integrated light amount was 22.17 mJ / cm ² .
The above-described peak illuminance and integrated light amount were measured by installing a UV METER (manufactured by Eyegraphic Co., Ltd., eye ultraviolet integrated illuminance meter UVPF-A1) attached with a light receiver at the position of the coating layer.
Moreover, the film thickness of the anisotropic light-diffusion film was measured using the constant pressure thickness measuring device (the Takara Seisakusho Co., Ltd. make, TECLOCK PG-02J).

Further, as shown in FIG. 9, the obtained anisotropic light diffusion film 10a has a plate-like region extending direction and a film length direction (moving direction of the coating layer) when the film surface is viewed from above. It was confirmed that the acute angle made by, was 0 °.
That is, even in a film in which the extending direction of the plate-like region and the longitudinal direction of the film coincide with each other, if the production method of the present invention is used, the anisotropic light is continuously generated without limiting the length in the longitudinal direction. It has been clarified that a diffusion film can be obtained, and as a result, an anisotropic light diffusion film obtained by winding the diffusion film can also be obtained.
Moreover, the photograph of the cross section which cut | disconnected the obtained anisotropic light-diffusion film 10a in the surface orthogonal to the elongate direction of a film is shown in Fig.10 (a) by the surface parallel to the elongate direction of a film, and orthogonal to a film surface. The photograph of the cut | disconnected cross section is shown in FIG.10 (b), respectively.
The anisotropic light diffusing film was cut using a razor, and a cross-sectional photograph was taken using a digital microscope (manufactured by Keyence Corporation, VHV-1000).

5. Measurement As shown in FIG. 9, light was incident on the film from the lower side of the obtained anisotropic light diffusion film 10a from the normal direction (incident angle θ1 = 0 °) of the film surface.
Next, a spectrum chart of diffused light in a direction perpendicular to the longitudinal direction of the film and in a direction parallel to the longitudinal direction of the film, using a colorimeter (VC-2 manufactured by Suga Test Instruments Co., Ltd.) Got.
That is, as shown in FIG. 11A, the horizontal axis represents the light diffusion angle (°) in the diffused light diffused by the anisotropic light diffusion film 10a, and the vertical axis represents the relative intensity (−) of the diffused light. A spectrum chart of the case was obtained.
Here, the spectrum chart A shown in FIG. 11A corresponds to the diffused light in the direction orthogonal to the longitudinal direction of the film, and the spectrum chart B represents the diffused light in the direction parallel to the longitudinal direction of the film. It corresponds to.
Moreover, the photograph of the diffused light at the time of seeing from the Z direction in FIG. 9 was obtained as shown in FIG.11 (b) using the conoscope (made by autotronic-MELCHERS GmbH).
The results shown in FIGS. 11 (a) to 11 (b) were consistent with the light diffusion characteristics expected from a film having an internal structure as shown in FIG.

[Example 2]
In Example 2, when the coating layer 1 was photocured, in FIG. 6, when the coating layer 1 obtained was viewed from above, it was different from the virtual line E ′ along the moving direction of the coating layer 1. Except for irradiating ultraviolet rays while translating at 0.32 m / min using a conveyor so that the light diffusing direction K of the isotropic light diffusing element 60 makes a right angle (acute angle is 90 °). An anisotropic light diffusion film 10b was produced in the same manner as in Example 1.
At this time, the peak illuminance on the surface of the coating layer 1 was 2.08 mW / cm ² , and the integrated light amount was 22.3 mJ / cm ² .

Further, as shown in FIG. 12, the obtained anisotropic light diffusing film 10b has a plate-like region extending direction and a film longitudinal direction (moving direction of the coating layer) when the film surface is viewed from above. , Made a right angle (acute angle of 90 °).
Further, similarly to Example 1, a photograph of a cross section of the obtained anisotropic light diffusion film 10b cut along a plane orthogonal to the longitudinal direction of the film is shown in FIG. The photograph of the cross section cut | disconnected by the surface orthogonal to a film surface is shown in FIG.13 (b), respectively.

Similarly to Example 1, from the lower side of the obtained anisotropic light diffusion film, the light diffusion condition when light is incident on the film from the normal direction of the film surface (incident angle θ1 = 0 °). Was measured.
FIG. 14A shows a spectrum chart of the obtained diffused light, and FIG. 14B shows a photograph of the diffused light when viewed from the Z direction in FIG.
The results shown in FIGS. 14 (a) to 14 (b) were consistent with the light diffusion characteristics expected from a film having an internal structure as shown in FIG.

[Comparative Example 1]
In Comparative Example 1, when the coating layer was photocured, ultraviolet rays were directly irradiated from a parallel light exposure device as an irradiation device without interposing a lens diffusion plate as an anisotropic light diffusing element, and the coating layer A light diffusion film was produced in the same manner as in Example 1 except that the moving speed was changed to 0.54 m / min.
At this time, the peak illuminance on the surface of the coating layer was 2.88 mW / cm ² , and the integrated light amount was 20.06 mJ / cm ² .

Further, as shown in FIG. 15, it was confirmed that the obtained light diffusion film 10′a had a column structure in which a plurality of high refractive index pillars were erected in a low refractive index region. .
Further, in the same manner as in Example 1, a photograph of a cross section obtained by cutting the obtained light diffusion film 10′a along a plane perpendicular to the longitudinal direction of the film is shown in FIG. And the photograph of the cross section cut | disconnected by the surface orthogonal to a film surface is shown in FIG.16 (b), respectively.

Similarly to Example 1, from the lower side of the obtained light diffusion film, the light diffusion state when light is incident on the film from the normal direction of the film surface (incident angle θ1 = 0 °). It was measured.
FIG. 17A shows a spectrum chart of the obtained diffused light, and FIG. 17B shows a photograph of the diffused light when viewed from the Z direction in FIG.
The results shown in FIGS. 17 (a) to 17 (b) were consistent with the light diffusion characteristics expected from a film having an internal structure as shown in FIG.

[Comparative Example 2]
In Comparative Example 2, when the coating layer is photocured, instead of interposing a lens diffusing plate as an anisotropic light diffusing element, an isotropic light diffusing plate having a wide diffusion angle is interposed and irradiated with ultraviolet rays. A film was produced in the same manner as in Example 1 except that the moving speed was changed to 8 m / min.
At this time, the peak illuminance on the surface of the coating layer was 11.0 mW / cm ² , and the integrated light amount was 32.0 mJ / cm ² .
The “isotropic light diffusing plate having a wide diffusion angle” means a light diffusing plate in which both θk and θh in FIG. 4 are very large.

Moreover, as shown in FIG. 18, obtained film 10'b was uniform and it confirmed that an internal structure was not seen especially.
Further, in the same manner as in Example 1, a photograph of a cross section obtained by cutting the obtained film 10′b along a plane orthogonal to the longitudinal direction of the film is shown in FIG. The photograph of the cross section cut | disconnected by the surface orthogonal to a surface is shown in FIG.19 (b), respectively.

Further, in the same manner as in Example 1, from the lower side of the obtained film, the degree of light diffusion was measured when light was incident on the film from the normal direction of the film surface (incident angle θ1 = 0 °). .
FIG. 20A shows a spectrum chart of the obtained diffused light, and FIG. 20B shows a photograph of the diffused light when viewed from the Z direction in FIG.
The results shown in FIGS. 20A to 20B were in agreement with the light diffusion characteristics expected from a film having an internal structure as shown in FIG.

As described above in detail, according to the present invention, when forming a louver structure, active energy rays as parallel light are applied to the coating layer through an anisotropic light diffusing element for diffusing irradiated light to anisotropic light. As compared with the case where a conventional linear light source is used, an anisotropic light diffusing film that effectively increases the degree of freedom in controlling the direction in which the incident light is diffused anisotropically can be obtained. .
Therefore, the method for producing an anisotropic light diffusing film of the present invention is expected to make a significant contribution to the productivity and quality improvement of a large area anisotropic light diffusing film particularly used in projection screens and reflective liquid crystal devices. The

1: coating layer, 2: process sheet, 10: anisotropic light diffusion film, 12: plate-like region having a relatively high refractive index, 13: louver structure, 13 ′: boundary surface of louver structure, 14: relatively refracting Plate-like region having a low rate, 50: active energy ray as parallel light, 50 ′: active energy ray having anisotropy, 60: anisotropic light diffusing element, 80: irradiation device, 82: light source, 84: lens

Claims (8)

A method for producing an anisotropic light diffusing film having a louver structure in which a plurality of plate-like regions having different refractive indexes are alternately arranged in any one direction along a film surface,
The manufacturing method of the anisotropic light-diffusion film characterized by including the following process (a)-(c).
(A) Step of preparing a composition for anisotropic light diffusing film containing two polymerizable compounds having different refractive indexes (b) Applying the composition for anisotropic light diffusing film to a step sheet to form a coating layer Step (c) When the application layer is irradiated with active energy rays as parallel light via an anisotropic light diffusing element for diffusing irradiated light to an anisotropic light, and viewed from above, the anisotropic light diffusing element Forming the louver structure in which the plate-like region extends in a direction parallel to the light diffusion direction;   In the step (c), the irradiation light is irradiated while moving the coating layer formed on the process sheet, and when viewed from above, an imaginary line along the moving direction of the coating layer and the different line The method for producing an anisotropic light diffusing film according to claim 1, wherein an acute angle formed by the light diffusion direction of the isotropic light diffusing element is set to a value of 80 ° or less.   3. The method for producing an anisotropic light diffusing film according to claim 1, wherein in the step (c), a lens diffusing plate having a plurality of microlenses on the surface is used as the anisotropic light diffusing element.   In the step (c), as the anisotropic light diffusing element, an interstitial anisotropic light diffusing film having a louver structure in which a plurality of plate-like regions having different refractive indexes are alternately arranged in any one direction along the film surface The method for producing an anisotropic light diffusing film according to claim 1 or 2, wherein:   In the said process (c), the parallelism of the active energy ray as said parallel light shall be a value of 10 degrees or less, The manufacture of the anisotropic light-diffusion film as described in any one of Claims 1-4 characterized by the above-mentioned. Method. The said process (c) WHEREIN: The peak illumination intensity of the said active energy ray in the surface of the said application layer is made into the value within the range of 0.1-50 mW / cm < ² >, Any one of Claims 1-5 characterized by the above-mentioned. The manufacturing method of the anisotropic light-diffusion film as described in a term. The said process (c) WHEREIN: The integrated light quantity of the said active energy ray in the surface of the said application layer is made into the value within the range of 5-300 mJ / cm < ² >, It is any one of Claims 1-6 characterized by the above-mentioned. The manufacturing method of the anisotropic light-diffusion film of description.   In the said process (c), the moving speed of the said application layer shall be a value within the range of 0.1-10 m / min, The anisotropic light-diffusion film as described in any one of Claims 2-7 characterized by the above-mentioned. Manufacturing method.