JP2013148712A - Composition for light-diffusing film, and light-diffusing film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for a light-diffusing film which has excellent incident angle dependency and a wide light diffusion incident angle area related to transmission and diffusion of light, keeps an opening angle in a long diameter direction of light diffusion, and has an enlarged opening angle in a short diameter direction thereof, and to provide a light-diffusing film.SOLUTION: In the composition for the light-diffusing film which contains a high refractive index polymerizable compound of component (A), a low refractive index polymerizable compound of component (B) and a photopolymerization initiator of component (C), the component (C) is an aryl glyoxylate ester-based compound represented by formula (1). (In formula (1), Rto Rare substituents of a hydrogen atom and the like, and Ris an alkyl group having a carbon number of 1 to 10, and the like.)

Description

The present invention relates to a composition for a light diffusion film and a light diffusion film.
In particular, the composition for a light diffusing film, which can obtain a light diffusing film having an incident angle dependency of diffusing or transmitting light passing through the film according to the incident angle of the light on the film surface, and the light The present invention relates to a cured light diffusion film.

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

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

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

  In addition, various modes are known as a light diffusion film used in a reflective liquid crystal display device, and in particular, an elongated plate-like high refractive index region and an elongated plate-like region along the film surface direction. Light diffusion films with a louver structure that can control the light direction and adjust the light dispersibility in the film by arranging the low refractive index regions alternately in parallel are widely used. (For example, Patent Documents 2 to 4).

  That is, Patent Document 2 discloses a film-shaped composition containing a plurality of compounds having a polymerizable carbon-carbon double bond, which is obtained by irradiating ultraviolet rays from a specific direction and curing the composition. In the light control film (light diffusion film) that selectively scatters only the incident light, at least one compound contained in the composition comprises a plurality of aromatic rings and one polymerizable carbon-carbon double bond. An optical control film characterized by being a compound contained in a molecule is disclosed.

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

  Further, Patent Document 4 includes at least (A) a bisphenol A type epoxy resin or brominated bisphenol A type epoxy resin represented by general formula (10), and (B) an ethylenically unsaturated bond in the structural unit. A light diffusion film comprising: a radically polymerizable compound comprising at least one, (D) a photopolymerization initiator that generates radical species by actinic radiation, and (E) a thermal polymerization initiator that generates cationic species by heat. A composition and a light diffusing film produced using the composition are disclosed. More specifically, at room temperature, (B) the compound having radical polymerizability has a refractive index of (A) bisphenol A type epoxy resin or brominated bisphenol A type epoxy resin and (C) at least one cationic polymerization in the molecule. The composition for light-diffusion films characterized by being lower than the compound which has a sex group, and the light-diffusion film manufactured using the same are disclosed.

(In the general formula (10), R represents a hydrogen atom or a bromine atom, and the repeat number p represents a natural number.)

On the other hand, by using a specific photopolymerization initiator, a method of expanding the width of the light diffusion incident angle region while improving the incident angle dependency is disclosed (for example, Patent Documents 5 to 6).
That is, Patent Document 5 contains at least two compounds each having a polymerizable carbon-carbon double bond in the molecule and having different refractive indexes, and an oxime compound as a photopolymerization initiator. And a light diffusing film produced using the same are disclosed.

  Patent Document 6 discloses at least two kinds of compounds having a polymerizable carbon-carbon double bond in each molecule and having different refractive indexes, and an aminoalkylphenone compound as a photopolymerization initiator. The photocurable composition characterized by containing and the light-diffusion film manufactured using the same are disclosed.

Japanese Patent No. 3480260 (Claims) JP 2006-350290 A (Claims) JP 2008-239757 A (Claims) Japanese Patent No. 3829601 (Claims) JP 2007-254646 A (Claims) JP 2008-37913 A (Claims)

However, the light diffusing films disclosed in Patent Documents 1 to 4 are not only poor in incident angle dependency in transmission and diffusion of light but also have a narrow light diffusing incident angle region. It was difficult to efficiently use
Although attempts have been made to increase the width of the light diffusing incident angle region by laminating a plurality of light diffusing films, the sharpness of the image is reduced, the iris color (moire phenomenon) appears, and the economy The problem of being disadvantageous was seen.
On the other hand, the light diffusing films disclosed in Patent Documents 5 to 6 could certainly widen the width of the light diffusing incident angle region to some extent while improving the incident angle dependency.
Accordingly, among the components included in the incident light, the component perpendicular to the direction of the louver structure extending along the film surface direction is effectively dispersed to increase the opening angle in the major axis direction in light diffusion. I was able to expand.
However, in the light diffusion films disclosed in Patent Documents 5 to 6, it is difficult to sufficiently diffuse the components parallel to the direction of the louver structure extending along the film surface direction among the components included in the incident light. There was a problem that the opening angle in the minor axis direction in light diffusion did not widen.
Therefore, even when the light diffusion films disclosed in Patent Documents 5 to 6 are used, it is still difficult to efficiently use external light at a level at which the reflective liquid crystal display device functions effectively. there were.

Accordingly, the inventors of the present invention have made extensive efforts in view of the above circumstances, and have a specific structure as a high refractive index polymerizable compound, a low refractive index polymerizable compound, and a photopolymerization initiator. The present invention has been completed by finding that a light diffusing film that solves the above-described problems can be obtained by blending an aryl glyoxylate ester compound and then photocuring.
That is, an object of the present invention is to have a good incident angle dependency in light transmission and diffusion, a wide light diffusion incident angle region, and maintain an opening angle in the minor axis direction while maintaining a major axis opening angle in light diffusion. An object of the present invention is to provide a light diffusing film that is also effectively enlarged in terms of corners, and a composition for a light diffusing film for obtaining the light diffusing film.

  According to the present invention, a light diffusing film comprising a high refractive index polymerizable compound as the component (A), a low refractive index polymerizable compound as the component (B), and a photopolymerization initiator as the component (C). There is provided a composition for a light diffusion film, wherein the photopolymerization initiator as the component (C) is an aryl glyoxylate ester compound represented by the following general formula (1): The above-mentioned problem can be solved.

(In General Formula (1), R < ¹ > -R < ⁵ > is respectively independent, a hydrogen atom, a hydroxyl group, a carboxyl group, a C1-C10 alkyl group, a C1-C10 alkoxy group, and C1-C1 A halogenated alkyl group having 1 to 10 carbon atoms, a hydroxyalkyl group having 1 to 10 carbon atoms, a carboxyalkyl group having 1 to 10 carbon atoms in the alkyl group, and a halogen atom, and R ⁶ is a carbon atom having 1 carbon atom. -10 alkyl group or C6-20 aryl group.)

Specifically, when (C) component which is a photoinitiator is photocured using an aryl glyoxylate ester compound having a specific structure, (A) cured product and (B) cured component Objects are extended alternately and efficiently form a louver structure in which elongated plate-like high refractive index regions and elongated plate-like low refractive index regions are arranged alternately in parallel along the film surface direction. can do.
Furthermore, by using the component (C) as a photopolymerization initiator, the obtained light diffusing film is not only light diffusive in the direction (major diameter direction) perpendicular to the direction of the louver structure extending along the film surface direction, Surprisingly, it can also exhibit light diffusibility in a direction parallel to the direction of the louver structure (minor axis direction), and has characteristics that could not be obtained with a light diffusing film having a conventional louver structure.
That is, the composition for a light diffusion film of the present invention has a good incident angle dependency in light transmission and diffusion, a wide light diffusion incident angle region, and maintains an opening angle in the major axis direction in light diffusion. However, it is possible to obtain a light diffusion film that is effectively enlarged with respect to the opening angle in the minor axis direction.
In the present invention, the “film surface direction” means a direction along the xy plane when the film thickness direction is the z-axis.
In the present invention, the “light diffusion incident angle region” means an incident light corresponding to emitting diffused light when the angle of incident light from a point light source is changed with respect to the light diffusing film. Means an angular range.
In addition, “good incident angle dependency” is a distinction between an incident angle region (light diffusion incident angle region) with respect to a film where light diffusion of incident light occurs and other incident angle regions where light diffusion does not occur. Means that it is clearly controlled.
Further, the “open angle in the major axis direction” and the “open angle in the minor axis direction” in the present invention mean the spread angle of the diffused light for each of the major axis direction and the minor axis direction in the diffused light spreading shape, Details of these will be described later.

Moreover, in comprising the composition for light-diffusion films of this invention, while making the compounding quantity of (A) component into the value within the range of 25-400 weight part with respect to 100 weight part of (B) component, (C) It is preferable to make the compounding quantity of a component into the value within the range of 2-20 weight part with respect to the total amount (100 weight part) of (A) component and (B) component.
By comprising in this way, with the compounding ratio with (A) component and (B) component, while the characteristic of (C) component is exhibited more effectively, in the stage of photocuring, predetermined louver structure Can be obtained more efficiently.

Moreover, when comprising the composition for light-diffusion films of this invention, it is preferable to make the maximum absorption wavelength of (C) component into the value within the range of 240-340 nm.
By configuring in this way, in combination with the wavelength of the irradiation light, the characteristics of the component (C) are more effectively exhibited, so in the stage of photocuring, a light diffusing film having a predetermined louver structure, It can be obtained more efficiently.

In constituting the light diffusing film composition of the present invention, in the general formula (1), together with R ¹ to R ⁵ is a hydrogen atom, that R ⁶ is an alkyl group having 1 to 4 carbon atoms preferable.
By comprising in this way, compatibility with (A) component and (B) component can be made favorable, and the characteristic of (C) component can be exhibited more effectively.

  In constituting the composition for light diffusion film of the present invention, the component (A) is a biphenyl compound represented by the following general formula (2), and the component (B) has a weight average molecular weight of 3,000 to 3,000. A polymerizable compound having a value in the range of 20,000 is preferred.

(In the general formula (2), R ^{7 to} R ¹⁶ are each independent, and at least one of R ^{7 to} R ¹⁶ is a substituent represented by the following general formula (3), and the rest is hydrogen. It is a substituent of any one of an atom, a hydroxyl group, a carboxyl group, an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, a carboxyalkyl group and a halogen atom.)

(In General Formula (3), R ¹⁷ is a hydrogen atom or a methyl group, carbon number n is an integer of 1 to 4, and repetition number m is an integer of 1 to 10.)

By comprising in this way, a predetermined difference is produced in the polymerization rate of (A) component and (B) component, and compatibility with (A) component and (B) component is reduced to a predetermined range. Thus, it is estimated that the copolymerizability between the two components can be reduced.
Therefore, the predetermined louver structure can be formed more efficiently.

Moreover, in constituting the composition for light diffusion films of the present invention, the component (B) is preferably urethane (meth) acrylate.
By comprising in this way, it is estimated that the copolymerizability of (A) component and (B) component can be reduced more.
Therefore, the predetermined louver structure can be formed more efficiently.

In constituting the composition for a light diffusion film of the present invention, 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.
By configuring in this way, it has a better incident angle dependency in light transmission and diffusion, and a wider light diffusion incident angle region, and while maintaining the opening angle in the major axis direction in light diffusion, the minor axis direction A light diffusing film that is further effectively enlarged with respect to the opening angle of can be obtained.

  Another aspect of the present invention is a light diffusing film obtained by irradiating an active energy ray to a composition for a light diffusing film and curing the composition, wherein the composition for a light diffusing film is a high component as the component (A). Including the refractive index polymerizable compound, the low refractive index polymerizable compound as the component (B), and the photopolymerization initiator as the component (C), the photopolymerization initiator as the component (C) A light diffusion film, which is an arylglyoxylate ester compound represented by the formula (1).

(In General Formula (1), R < ¹ > -R < ⁵ > is respectively independent, a hydrogen atom, a hydroxyl group, a carboxyl group, a C1-C10 alkyl group, a C1-C10 alkoxy group, and C1-C1 A halogenated alkyl group having 1 to 10 carbon atoms, a hydroxyalkyl group having 1 to 10 carbon atoms, a carboxyalkyl group having 1 to 10 carbon atoms in the alkyl group, and a halogen atom, and R ⁶ is a carbon atom having 1 carbon atom. -10 alkyl group or C6-20 aryl group.)

  That is, since the light diffusion film of the present invention is obtained by photocuring a predetermined composition for light diffusion film, it has good incident angle dependency in light transmission and diffusion, and a wide light diffusion incident angle region. In addition, it is possible to obtain a light diffusion film that effectively expands the opening angle in the minor axis direction while maintaining the opening angle in the major axis direction in light diffusion.

Moreover, when comprising the light-diffusion film of this invention, it is preferable to make a film thickness into the value within the range of 100-500 micrometers.
With this configuration, it is possible to efficiently use external light as a light source even when it is applied to a reflective liquid crystal display device or the like as a single layer without laminating a light diffusion film. In addition, it is possible to prevent problems such as a decrease in the sharpness of the displayed image and the appearance of an iris color.

Fig.1 (a)-(b) is a figure provided in order to demonstrate the outline of the louver structure in a light-diffusion film. FIGS. 2A to 2C are diagrams provided to explain incident angle dependency, anisotropy, and an opening angle in a light diffusion film. FIG. 3A to FIG. 3C are other diagrams provided for explaining the incident angle dependency, anisotropy, and opening angle in the light diffusion film. FIG. 4 is a diagram provided for explaining the relationship between the blending amount of the component (C) and the opening angle in the minor axis direction in light diffusion. FIG. 5A to FIG. 5C are conceptual diagrams provided for explaining a method for producing a light diffusion film. FIGS. 6A to 6B are diagrams provided for explaining the photocuring process. FIGS. 7A to 7C are views provided to explain the embodiment of the louver structure in the light diffusion film of the present invention. FIG. 8 is a diagram for explaining an application example of a light diffusion film in a reflective liquid crystal display device. FIGS. 9A to 9G are diagrams for explaining the spread of diffused light and the distribution of lightness in the light diffusion film of Example 1. FIG. FIGS. 10A to 10L are diagrams used to explain the spread of diffused light and the distribution of brightness in the light diffusing films of Examples 2 to 7 and Comparative Examples 1 to 6. FIG. FIGS. 11A and 11B are views for explaining a reflection type liquid crystal display device using a conventional light diffusion film.

[First Embodiment]
The first embodiment of the present invention comprises a high refractive index polymerizable compound as component (A), a low refractive index polymerizable compound as component (B), and a photopolymerization initiator as component (C). A composition for a light diffusing film, wherein the photopolymerization initiator as the component (C) is an arylglyoxylate ester compound represented by the general formula (1) It is.
Hereinafter, a first embodiment of the present invention will be specifically described with reference to the drawings as appropriate.

1. Basic Principle of Light Diffusion Film First, the basic principle of a light diffusion film (hereinafter simply referred to as a light diffusion film) obtained by photocuring the composition for a light diffusion film of the present invention with reference to FIGS. Will be described.
First, FIG. 1A shows a top view (plan view) of the light diffusion film 10, and FIG. 1B shows the light diffusion film 10 shown in FIG. A cross-sectional view of the light diffusion film 10 when cut in the vertical direction along A and viewing the cut surface from the arrow direction is shown.
2 (a) represents an overall view of the light diffusing film, FIG. 2 (b) represents a cross-sectional view of the light diffusing film of FIG. 2 (a) viewed from the X direction, and FIG. c) represents a cross-sectional view of the light diffusion film of FIG. 2A when viewed from the Y direction.
As shown in the plan view of FIG. 1A, the light diffusion film 10 includes a plate-like region 12 having a relatively high refractive index derived from the component (A) along the film surface direction, and (B). It has a louver structure 13 in which plate-like regions 14 having a relatively low refractive index derived from components are alternately arranged in parallel.
Further, as shown in the cross-sectional view of FIG. 1B, the high refractive index plate-like region 12 derived from the component (A) and the low refractive index plate-like region 14 derived from the component (B) are respectively It has a predetermined thickness and maintains a state of being alternately arranged in parallel in the vertical direction of the light diffusion film 10.

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 will be diffused by the light-diffusion film 10. FIG.
That is, as shown in FIG. 1B, the incident angle of the incident light with respect to the light diffusion film 10 is a value within a predetermined angle range from parallel or parallel to the boundary surface 13 ′ of the louver structure 13, that is, light When the value is within the diffuse incident angle region, the incident light (52, 54) passes through the high refractive index plate-like region 12 in the louver structure along the film thickness direction while changing the direction. Thus, it is estimated that the traveling direction of light on the light exit surface side is not uniform.
As a result, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused by the light diffusion film 10 (52 ′, 54 ′).
On the other hand, when the incident angle of the incident light with respect to the light diffusion film 10 deviates from the light diffusion incident angle region, the incident light 56 is not diffused by the light diffusion film as shown in FIG. It is estimated that the light diffusing film 10 is transmitted as it is (56 ').

Based on the above basic principle, the light diffusing film 10 provided with the louver structure 13 can exhibit incident angle dependency in light transmission and diffusion, for example, as shown in FIG.
In addition, as shown in FIG. 2 (a), the light diffusing film has an incident angle of incident light included in the light diffusing incident angle region. Almost the same light diffusion can be achieved.
Therefore, it can be said that the light diffusing film also has a light collecting function for concentrating light at a predetermined location.

The light diffusing incident angle region is an angle region determined for each light diffusing film depending on a refractive index difference, an inclination angle, or the like of the louver structure in the light diffusing film, as shown in FIG.
Further, the direction change of the incident light in 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 that changes direction may be considered.

Moreover, as a composition for light-diffusion films in this embodiment, it is preferable that the obtained light-diffusion film has anisotropy (Hereinafter, it may be called an "anisotropic light-diffusion film.").
Here, “anisotropy” means, as shown in FIGS. 2A to 2C, when light is diffused by the film, in the plane parallel to the film in the diffused emitted light, It means that the light diffusion state (the shape of the spread of the diffused light) has different properties depending on the direction in the same plane.
More specifically, as shown in FIGS. 2A to 2C, among the components included in the incident light, a component perpendicular to the direction of the louver structure extending along the film surface direction is selectively used. Light diffusion occurs (see FIG. 2B).
On the other hand, among the components included in the incident light, light diffusion is difficult to occur with respect to a component parallel to the direction of the louver structure extending along the film surface direction (see FIG. 2C).
Thereby, 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 the film surface direction, and as shown in FIG. In the present invention, the “incident angle θ1” of incident light means an incident angle of a component perpendicular to the direction of the louver structure extending along the film surface direction. Further, at this time, the incident angle θ1 means an angle (°) when the angle of incidence perpendicular to the anisotropic light diffusion film is 0 °.

In the present invention, the “open angle in the major axis direction in light diffusion” refers to a cross section of the film from a direction X parallel to the direction of the louver structure extending along the film surface direction, as shown in FIG. Is the opening angle θ2 of the diffused light when looking at.
Furthermore, in the present invention, “the opening angle in the minor axis direction in light diffusion” means, as shown in FIG. 2C, from the direction Y perpendicular to the direction of the louver structure extending along the film surface direction. It means an opening angle θ3 of diffused light when a cross section is viewed.
Further, “major axis” and “minor axis” mean a major axis and a minor axis in a substantially elliptical shape, which is the shape of spread of diffused light.
In addition, when using a light-diffusion film as a light-diffusion plate of a reflection-type liquid crystal display device, it is confirmed that (theta) 2 by the definition mentioned above has no problem practically if it is in the range of 1-90 degrees. A value in the range of 70 ° is more preferable.
Similarly, θ3 according to the above definition is preferably a value within the range of 0 to 80 °, and more preferably within a range of 30 to 50 °.

2. Increasing the opening angle in the minor axis direction The light diffusing film obtained by photocuring the composition for light diffusing film of the present invention has a feature that the opening angle in the minor axis direction in light diffusion can be expanded. .
Hereinafter, the mechanism by which the opening angle θ3 in the minor axis direction is enlarged will be described with reference to FIGS.
3A shows an estimated overall view of the light diffusion film of the present embodiment, and FIG. 3B is a cross-section when the light diffusion film of FIG. 3A is viewed from the X direction. FIG. 3C shows a cross-sectional view estimated when the light diffusion film of FIG. 3A is viewed from the Y direction.
That is, in the light diffusion film of the present invention, as shown in FIG. 3 (a), the plate-like region having a high refractive index in the louver structure is divided at a predetermined frequency along the film surface direction. Estimated.
That is, as shown in FIG. 3C, even in a direction parallel to the louver structure, there are divided portions having different refractive indexes in the louver structure, and high refractive index regions and low refractive regions are formed in the louver structure in some places. It is estimated that
For this reason, it is presumed that the light diffusion effect can be obtained by a mechanism similar to the direction perpendicular to the louver structure as described in FIG.
Thereby, it is presumed that, among the components included in the incident light, the components parallel to the direction of the louver structure extending along the film surface direction are likely to cause light diffusion within a predetermined range.
Therefore, if it is a light diffusion film obtained by photocuring the composition for light diffusion films of this invention, as shown in FIG.3 (b) and (c), it is favorable incident angle dependence in light transmission and a spreading | diffusion. It is estimated that the aperture angle in the minor axis direction can be effectively enlarged while maintaining the aperture angle in the major axis direction in the light diffusion.

3. (A) Component: High Refractive Index Polymerizable Compound The light diffusing film composition of the present invention is characterized by containing a high refractive index polymerizable compound as the (A) component.
This is because a predetermined louver structure can be effectively obtained when photocured in combination with the action of the components (B) and (C) described later.
In the present invention, “high refractive index” means that the refractive index is high in relation to the component (B).

(1) Kind Moreover, although the kind of high refractive index polymeric compound as (A) component is not specifically limited, It is preferable to make the main component into the (meth) acrylic acid ester containing a some aromatic ring.
The reason for this is that by including a specific (meth) acrylic acid ester as the component (A), the polymerization rate of the component (A) is made faster than the polymerization rate of the component (B), This is because it is presumed that a predetermined difference is caused in the polymerization rate, and the copolymerizability of both components can be effectively reduced.
As a result, when photocured, a so-called louver structure in which the cured product of component (A) and the cured product of 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 portion derived from the component (A) in the louver structure is increased, and the refraction of the portion derived from the component (B). The difference from the rate can be adjusted to a value above 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. A light diffusion film can be obtained efficiently.
Therefore, it is possible to obtain a light diffusion film having good incident angle dependency in light transmission and diffusion and having a wide light diffusion incident angle region.
The “(meth) acrylic acid ester containing a plurality of aromatic rings” means a compound having a plurality of aromatic rings in the esterified portion of the (meth) acrylic acid ester.
“(Meth) acrylic acid” means both acrylic acid and methacrylic acid.

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

  Moreover, it is preferable that the (meth) acrylic acid ester containing a plurality of aromatic rings as the component (A) includes a compound containing a biphenyl ring, and particularly includes a biphenyl compound represented by the following general formula (2). It is preferable.

(In the general formula (2), R ^{7 to} R ¹⁶ are each independent, and at least one of R ^{7 to} R ¹⁶ is a substituent represented by the following general formula (3), and the rest is hydrogen. It is a substituent of any one of an atom, a hydroxyl group, a carboxyl group, an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, a carboxyalkyl group and a halogen atom.)

(In General Formula (3), R ¹⁷ is a hydrogen atom or a methyl group, carbon number n is an integer of 1 to 4, and repetition number m is an integer of 1 to 10.)

The reason for this is that by including a biphenyl compound having a specific structure as the component (A), a predetermined difference is caused in the polymerization rate of the component (A) and the component (B), and the component (A) and the component (B) This is because it is estimated that the compatibility between the two components can be reduced by reducing the compatibility with the component to a predetermined range.
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.
Furthermore, the component (A) becomes liquid at the monomer stage before photocuring, and can be uniformly mixed with the component (B) in the applicable viscosity region without using a diluting solvent or the like.

Further, R ⁷ to R ¹⁶ in the general formula (2) is an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, and if it contains any of the carboxyalkyl group, the carbon number of the alkyl moiety 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) in the louver structure becomes too low. This is because it may be difficult to efficiently form a predetermined louver structure in the light diffusion film.
Therefore, when R ^{7 to} R ¹⁶ in the general formula (2) include any one 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.

In addition, R ^{7 to} R ¹⁶ in the general formula (2) are preferably a halogenated alkyl group or a substituent other than a halogen atom, that is, a halogen-free substituent.
This is because dioxins are prevented from being generated when the light diffusing film is incinerated, and is preferable from the viewpoint of environmental protection.
Incidentally, in a light diffusion film having a conventional louver structure, in order to obtain a predetermined louver structure, it is general that halogen substitution is performed on the monomer component for the purpose of increasing the refractive index of the monomer component.
In this respect, the biphenyl compound represented by the general formula (2) can have a high refractive index even when halogen substitution is not performed.
Therefore, if it is a light-diffusion film formed by photocuring the composition for light-diffusion films of this invention, even if it does not contain a halogen, favorable incident angle dependence can be exhibited.

Moreover, it is preferable that any one of R < ⁸ > -R < ¹⁵ > in General formula (2) is a substituent represented by General formula (3).
This is because, by setting the position of the substituent represented by the general formula (3) to a position other than R ⁷ and R ¹⁶ , the components (A) are oriented and crystallized in the stage before photocuring. This can be effectively prevented.
Thereby, in the stage of photocuring, it is possible to agglomerate and phase-separate the component (A) and the component (B) at a fine level, and more efficiently obtain a light diffusion film having a predetermined louver structure. It is because it can do.
Furthermore, from the same viewpoint, it is particularly preferable that any one of R ⁹ , R ¹¹ , R ¹² and R ^{14 in} the general formula (2) is a substituent represented by the general formula (3).

Moreover, it is preferable to make the repeating number m in the substituent represented by General formula (3) 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 (3) is more preferably an integer of 1 to 4, and particularly preferably an integer of 1 to 2.
In addition, from the same viewpoint, it is preferable that the carbon number n in the substituent represented by the general formula (3) is generally 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 (3) 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 (2) include compounds represented by the following formulas (4) to (5).

(2) Molecular weight Moreover, it is preferable to make the molecular weight of the high refractive index polymeric compound as a (A) component into the value within the range of 200-2,500.
This is because, by setting the molecular weight of the high refractive index polymerizable compound as the component (A) within a predetermined range, the polymerization rate of the component (A) is further increased, and the components (A) and (B) This is because it is estimated that the copolymerizability can be more effectively 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.
Accordingly, the molecular weight of the high refractive index polymerizable compound as 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. preferable.
In addition, the molecular weight of (A) component can be calculated | required from the calculated value obtained from a molecular composition and the atomic weight of a constituent atom.
Moreover, when calculation from a calculated value is difficult, it can also measure as a weight average molecular weight (Mw) using gel permeation chromatography (GPC).

(3) Single use Moreover, although the composition for light-diffusion films of this invention is characterized by including (A) component as a monomer component which forms a plate-shaped area | region with a high refractive index in a louver structure, a monomer component It is preferable to use the component (A) alone.
The reason for this is that, by configuring in this way, the variation in the refractive index in the plate-like region derived from the component (A) in the louver structure, that is, the plate-like region having a high refractive index, is effectively suppressed, and a predetermined louver is obtained. This is because the light diffusing film having the structure 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 high refractive index derived from the component (A) may vary or be easily lowered.
As a result, the refractive index difference from the plate-like region having a 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 to use it as a single component (A).
For example, since the biphenyl compound represented by the formula (4) as the component (A) has a low viscosity, it has compatibility with the component (B), so it can be used as a single component (A). can do.

(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) in the louver structure and the plate-like region derived from the component (B) are obtained by setting the refractive index of the component (A) within this range. This is because the light diffusion film having a predetermined louver structure can be more efficiently obtained by more easily adjusting the difference from the refractive index.
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 a desired incident angle dependency. Because there is. On the other hand, when the refractive index of the component (A) exceeds 1.65, the difference from the refractive index of the component (B) increases, but compatibility with the component (B) before curing becomes difficult. This is because there are cases.
Therefore, the refractive index of the component (A) is more preferably set to a value within the range of 1.55 to 1.6, and further preferably set to a value within the range of 1.56 to 1.59.
In addition, the refractive index of (A) component mentioned above means the refractive index of (A) component before hardening by light irradiation.
The refractive index can be measured according to, for example, JIS K0062.

(5) Compounding quantity Moreover, it is preferable to make content of (A) component into the value within the range of 25-400 weight part with respect to 100 weight part of (B) component mentioned later.
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 plate shape derived from the component (A) in the louver structure This is because the width of the region becomes excessively small as compared with the width of the plate-like region derived from the component (B), 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 light diffusing film becomes insufficient, and the light diffusing property 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 plate-like region derived from the component (A) in the louver structure This is because it may become difficult to obtain a louver structure having a good incident angle dependence, on the contrary, the width of the plate is excessively larger than the width of the plate-like region derived from the component (B). is there. Moreover, it is because the length of the louver in the thickness direction of the light diffusing film becomes insufficient, and the light diffusing property may not be exhibited.
Therefore, it is more preferable to set the content of the component (A) to a value within the range of 40 to 300 parts by weight with respect to 100 parts by weight of the component (B), and a value within the range of 50 to 200 parts by weight. More preferably.

4). (B) Component: Low Refractive Index Polymerizable Compound The light diffusion film composition of the present invention is characterized by containing a low refractive index polymerizable compound as the (B) component.
This is because a predetermined louver structure can be effectively obtained when photocured in combination with the action of the components (B) and (C).
In the present invention, “low refractive index” means that the refractive index is low in relation to the component (A) described above.

(1) Kind Moreover, the kind of low refractive index polymeric compound as (B) component is not specifically limited, As a main component, it has a (meth) acryloyl group in a urethane (meth) acrylate and a side chain, for example. (Meth) acrylic polymers, (meth) acryloyl group-containing silicone resins, unsaturated polyester resins and the like can be mentioned, and urethane (meth) acrylates are particularly preferable.
The reason for this is that if it is urethane (meth) acrylate, the difference between the refractive index of the plate-like region derived from the component (A) in the louver structure and the refractive index of the plate-like region derived from the component (B) is more In addition to being easily adjustable, it is possible to effectively suppress variation in the refractive index of the plate-like region derived from the component (B) and to obtain a light diffusion film having a predetermined louver structure more efficiently. is there.
Therefore, in the following, urethane (meth) acrylate as the component (B) will be mainly described.
In addition, (meth) acrylate means both acrylate and methacrylate.

First, urethane (meth) acrylate is formed from (a) a compound containing at least two isocyanate groups, (b) polyalkylene glycol, and (c) hydroxyalkyl (meth) acrylate.
Among these, as the compound containing at least two isocyanate groups as component (a), for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate Arocyclic polyisocyanates such as aromatic polyisocyanates such as 1,4-xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, etc. Isocyanates and their biurets, isocyanurates, and adducts that are a reaction with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil (for example, Xylylene diisocyanate Over preparative based trifunctional adduct), and the like.

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

Moreover, if it is an alicyclic polyisocyanate, compared with an aromatic polyisocyanate, the low refractive index polymeric compound as (B) component obtained and the high refractive index polymeric compound as (A) component will be obtained. The louver structure can be formed more efficiently by reducing the compatibility with the louver.
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 having a large incident angle dependency 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 (b) and the component (c) to obtain a single component (B).
As such an alicyclic diisocyanate, isophorone diisocyanate (IPDI) can be particularly preferably mentioned.
This is because an effective difference can be provided in the reactivity of the two isocyanate groups.

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

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

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

(2) Weight average molecular weight Moreover, it is preferable to make the weight average molecular weight of the low refractive index polymeric compound as (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 polymerizable compound as the component (B) within a predetermined range, a predetermined difference is caused in the polymerization rate of the component (A) and the component (B). This is because the polymerizability can be effectively reduced.
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 lowered, and the component (A) may be precipitated at the application 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).

(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 dispersion | variation in the refractive index of the plate-shaped area | region derived from the (B) component in a louver structure It is preferable to use it alone from the viewpoint of suppressing the above.
That is, when a plurality of components (B) are used, the refractive index in the plate-like region having a low refractive index derived from the component (B) varies or increases, and the refractive index derived from the component (A) is high. This is because the refractive index difference from the plate-like region may become non-uniform or excessively decrease.

(4) Refractive index Moreover, it is preferable to make the refractive index of (B) component into the value within the range of 1.4-1.5.
This is because the refractive index of the plate-like region derived from the component (A) and the plate-like region derived from the component (B) in the louver structure is determined by setting the refractive index of the component (B) to a value within this range. This is because the light diffusion film having a predetermined louver structure can be more efficiently obtained by adjusting the difference between the two and the difference more easily.
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, if the refractive index of the component (B) exceeds 1.5, the difference from the refractive index of the component (A) becomes too small, making it difficult to obtain the desired incident angle dependency. Because there is.
Therefore, the refractive index of the component (B) is more preferably set to a value within the range of 1.45 to 1.49, and further preferably set to a value within the range of 1.46 to 1.48.
In addition, the refractive index of (B) component mentioned above means the refractive index of (B) component before hardening by light irradiation.
The refractive index can be measured, for example, according to JIS K0062.

The difference between the refractive index of the component (A) and the refractive index of the component (B) is preferably set to a value of 0.01 or more.
The reason for this is that by making the difference in refractive index a value within a predetermined range, it has a better incident angle dependency in light transmission and diffusion, and a wider light diffusion incident angle region, and in light diffusion. This is because it is possible to obtain a light diffusion film in which the opening angle in the minor axis direction is further effectively enlarged while maintaining the opening angle in the major axis direction.
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, and therefore the opening angle in the major axis direction and minor axis direction in light diffusion is excessive. This is because it may become narrower. 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.
The difference in refractive index between the component (A) and the component (B) here means the difference in refractive index between the component (A) and the component (B) before being cured by light irradiation.

5. Component (C): Photopolymerization Initiator (1) Type The composition for a light diffusion film of the present invention is an arylglyoxylate ester represented by the following general formula (1) as a component (C) that is a photopolymerization initiator. It is characterized by using a compound.

(In General Formula (1), R < ¹ > -R < ⁵ > is respectively independent, a hydrogen atom, a hydroxyl group, a carboxyl group, a C1-C10 alkyl group, a C1-C10 alkoxy group, and C1-C1 A halogenated alkyl group having 1 to 10 carbon atoms, a hydroxyalkyl group having 1 to 10 carbon atoms, a carboxyalkyl group having 1 to 10 carbon atoms in the alkyl group, and a halogen atom, and R ⁶ is a carbon atom having 1 carbon atom. -10 alkyl group or C6-20 aryl group.)

The reason for this is that when the photopolymerization initiator (C) component is an arylglyoxylate ester-based compound having a specific structure, when photocured, the cured product (A) and (B) A louver structure in which cured products of the components are alternately extended and arranged so that elongated plate-like high refractive index regions and elongated plate-like low refractive index regions are alternately arranged in parallel along the film surface direction. This is because it can be formed efficiently.
On the other hand, due to the characteristics of the arylglyoxylate ester compound having such a specific structure, as shown in FIG. 3A, an elongated plate-like high refractive index region and an elongated plate-like low refractive index region It is estimated that the length in the film surface direction can be formed with a relatively short length.
Here, the aryl glyoxylate ester compound having a specific structure is relatively susceptible to oxygen inhibition, and when polymerizing the component (A) and the component (B), the reaction efficiency is within a predetermined range. It is presumed to be suppressed.
Then, it is estimated that the suppression of the reaction efficiency contributes to the formation of a predetermined louver structure as shown in FIG.
In any case, the composition for a light diffusion film of the present invention has good incident angle dependency in light transmission and diffusion, a wide light diffusion incident angle region, and an opening angle in the major axis direction in light diffusion. A light diffusing film that is effectively enlarged with respect to the opening angle in the minor axis direction can be obtained.

Moreover, in General formula (1), while R < ¹ > -R < ⁵ > is a hydrogen atom, it is preferable that R < ⁶ > is a C1-C4 alkyl group.
By comprising in this way, since the characteristic of (C) component is exhibited more effectively, the light-diffusion film provided with the predetermined | prescribed louver structure can be obtained more efficiently in the stage of photocuring. it can.
That is, by making (C) component into the structure mentioned above, compatibility with (A) component and (B) component can be improved, and it can disperse | distribute uniformly in the composition for light-diffusion films, and is obtained. This is because the reproduction characteristics of the light diffusion film can be stabilized.

  Further, among the aryl glyoxylic acid ester compounds represented by the general formula (1), compounds particularly preferably used include compounds represented by the following formula (6).

(2) Maximum absorption wavelength It is preferable to set the maximum absorption wavelength of the component (C) to a value within the range of 240 to 340 nm.
By configuring in this way, in combination with the wavelength of the irradiation light, the characteristics of the component (C) are more effectively exhibited, so in the stage of photocuring, a light diffusing film having a predetermined louver structure, It can be obtained more efficiently.
That is, when the maximum absorption wavelength of the component (C) is less than 240 nm, the thickness of the louver structure in the film thickness direction becomes too thin, and it may be difficult to obtain sufficient light diffusibility. . On the other hand, when the maximum absorption wavelength of the component (C) is a value exceeding 340 nm, a part of the photopolymerization initiator reacts first with the surrounding visible light, which may cause deterioration in performance. .
Therefore, the maximum absorption wavelength of the component (C) is more preferably set to a value within the range of 250 to 330 nm, and further preferably set to a value within the range of 255 to 325 nm.
In addition, the maximum absorption wavelength of (C) component can be measured using an ultraviolet spectrophotometer.

(3) Compounding quantity Moreover, the compounding quantity of (C) component shall be the value within the range of 2-20 weight part with respect to the total amount (100 weight part) of (A) component and (B) component. Is preferred.
By comprising in this way, since the characteristic of (C) component is exhibited more effectively together with the mixture ratio with (A) component and (B) component, in the stage of photocuring, predetermined louver A light diffusion film having a structure can be obtained more efficiently.
That is, when the blending amount of component (C) is less than 2 parts by weight, the incident angle dependency in light transmission and diffusion decreases, and the opening angle in the major axis direction and minor axis direction in light diffusion becomes narrower. Because there is.
On the other hand, when the amount of component (C) exceeds 20 parts by weight, odor and coloring problems may occur in the obtained light diffusion film, and unreacted residues may deteriorate the film. Because.
Therefore, the blending amount of the component (C) is more preferably 3 to 15 parts by weight with respect to the total amount (100 parts by weight) of the component (A) and the component (B). More preferably, the value is within the range of 10 parts by weight.

(4) Relationship between blending amount and opening angle in minor axis direction Next, with reference to FIG. 4, the blending amount of an arylglyoxylate ester compound having a specific structure as component (C) and the minor axis in light diffusion A relationship with the opening angle of the direction will be described.
That is, in FIG. 4, the horizontal axis represents the blending amount (parts by weight) of the photopolymerization initiator relative to the total amount (100 parts by weight) of the components (A) and (B), and the vertical axis represents the light diffusion film. Characteristic curves A and B taking the minor angle direction opening angle (°) in the light diffusion by are shown.
Here, the characteristic curve A is a compound (phenylglyoxylic acid methyl ester) represented by the formula (6), which is one of the aryloxylic acid ester-based compounds having a specific structure as the component (C) as a photopolymerization initiator. It is a characteristic curve at the time of using.
On the other hand, the characteristic curve B is a characteristic curve when a compound (2-hydroxy-2-methylpropionphenone) represented by the following formula (7) which is a compound not corresponding to the component (C) is used as a photopolymerization initiator. is there.
The details of the configuration of the light diffusion film, the method of measuring the opening angle in the minor axis direction, and the like are the same as in Example 1.

First, as understood from the characteristic curve A, when an aryloxylate ester compound having a specific structure as the component (C) is used as a photopolymerization initiator, the blending amount (part by weight) increases. Thus, the opening angle (°) in the minor axis direction starts to increase rapidly, and then maintains a large value.
And when the compounding quantity is in the range of 2 to 10 parts by weight, it can be seen that the opening angle in the minor axis direction can be stably maintained at a wide value of 32 ° or more.
On the other hand, as understood from the characteristic curve B, when a compound that does not correspond to the component (C) is used as the photopolymerization initiator, the opening angle in the minor axis direction (with parts by weight) increases ( )) Gradually increases at first, but increases to around 30 ° in the vicinity of 5 parts by weight. After that, it continues to decrease gradually, and at 10 parts by weight it becomes a low value of around 28 °. .
Therefore, it is understood that the use of an aryloxylate ester compound having a specific structure as component (C) as a photopolymerization initiator contributes to specifically increasing the opening angle in the minor axis direction. Is done.
Further, the blending amount is more efficiently in the minor axis direction by setting the value within the range of 2 to 10 parts by weight with respect to the total amount (100 parts by weight) of the components (A) and (B). It is understood that the opening angle of can be expanded.
In the graph in FIG. 4, the opening angle in the major axis direction is not mentioned, but in the range of 2 to 10 parts by weight of the photopolymerization initiator, both the characteristic curves A and B have a major axis direction. It has been separately confirmed that the opening angle is a sufficiently wide value of 40 ° or more.

(5) Other photopolymerization initiators It is also preferred to use other photopolymerization initiators together with the arylglyoxylate ester compound having a specific structure as the component (C).
The reason for this is that even when a photopolymerization initiator other than an arylglyoxylate ester compound having a specific structure is used in combination with an arylglyoxylate ester compound having a specific structure, a predetermined louver structure is effectively obtained. This is because it can be formed.
As a result, it has a good incident angle dependency in light transmission and diffusion, and a wide light diffusion incident angle region, and further has an effect on the opening angle in the minor axis direction while maintaining the opening angle in the major axis direction in light diffusion. An optically expanded light diffusion film can be obtained.

  Examples of other photopolymerization initiators 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-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethyl Thioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylamine benzoate, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propane, etc. Is mentioned.

  Moreover, when using together with another photoinitiator, the compounding quantity is the range of 1-200 weight part with respect to 100 weight part of aryl glyoxylic acid ester-type compounds which have a specific structure as (C) component. The value is preferably in the range of 10 to 150 parts by weight, more preferably in the range of 50 to 100 parts by weight.

6). 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 addition, generally the addition amount of such an additive shall be the value within the range of 0.01-5 weight part with respect to the total amount (100 weight part) of (A) component and (B) component. Is preferable, it is more preferable to set it as the value within the range of 0.02-3 weight part, and it is further more preferable to set it as the value within the range of 0.05-2 weight part.

[Second Embodiment]
2nd Embodiment of this invention is a light-diffusion film formed by irradiating and curing an active energy ray with respect to the composition for light-diffusion films, Comprising: The composition for light-diffusion films is high as (A) component. A refractive index polymerizable compound, a low refractive index polymerizable compound as the component (B), and a photopolymerization initiator as the component (C), and a photopolymerization initiator as the component (C) are represented by the general formula It is an aryl glyoxylate ester compound represented by (1).
Hereinafter, the second embodiment of the present invention will be specifically described with reference to the drawings with a focus on differences from the first embodiment.

1. Manufacturing method Hereinafter, the manufacturing method of the light-diffusion film of this invention is demonstrated, Needless to say, the light-diffusion film concerning this invention is not limited by the following manufacturing methods.

(1) Preparation Step for Composition for Light Diffusion Film The composition for light diffusion film is a step for preparing a predetermined composition for light diffusion film containing the component (A), the component (B) and the component (C). .
More specifically, it is preferable to stir the component (A), the component (B) and the component (C) under high temperature conditions of 40 to 80 ° C. to obtain a uniform mixed solution.
At the same time, after adding other additives to the mixture, if necessary, add a diluting solvent as necessary to achieve the desired viscosity while stirring until it appears uniform. Thus, it is preferable to obtain a solution of the composition for light diffusion film.
In addition, since it is as having described in 1st Embodiment about the detail of each component, a mixture ratio, etc., it abbreviate | omits.

(2) Application process An application process is a process of forming the application layer 1 by applying the prepared composition for light diffusion film to the process sheet 2 as shown in FIG.
Either a plastic film or paper can be used as the process sheet.
Among these, examples of the plastic film include polyester films such as polyethylene terephthalate films, polyolefin films such as polyethylene films and polypropylene films, cellulose films such as triacetyl cellulose films, and polyimide films.
Examples of the paper include glassine paper, coated paper, and laminated paper.

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

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

(3) Photocuring step The photocuring step is a step of photocuring the coating layer of the composition for a light diffusing film to make the coating layer a light diffusing film.
That is, as shown in FIG. 5B, the active energy ray 50 composed only of direct light whose irradiation angle is controlled is irradiated onto the coating layer 1 formed on the process sheet 2.
More specifically, for example, as shown in FIG. 6A, an ultraviolet irradiation device 20 in which a condensing cold mirror 22 is provided on a linear ultraviolet lamp 25 (for example, a commercially available product is an eyepiece). By placing the heat ray cut filter 21 and the light-shielding plate 23 in the graphics (ECS-4011GX, etc.), the active energy ray 50 consisting only of the direct light whose irradiation angle is controlled is taken out. Irradiate the coating layer 1 formed above.
The linear ultraviolet lamp usually has a value in the range of −80 to 80 °, preferably −50 to 50 with respect to the direction (0 °) perpendicular to the longitudinal direction of the process sheet 2 having the coating layer 1. It is installed so as to have a value in the range of °, particularly preferably in the range of -30 to 30 °.
At this time, as the irradiation angle of the irradiation light, as shown in FIG. 6B, the irradiation angle θ4 when the vertical angle is 0 ° with respect to the surface of the coating layer 1 is usually −80 to A value within the range of 80 ° is preferable.
This is because when the irradiation angle θ4 is a value outside the range of −80 to 80 °, the influence of reflection on the surface of the coating layer 1 becomes large, and it becomes difficult to form a sufficient louver structure. Because there is.
The irradiation angle θ4 preferably has a width (irradiation angle width) θ4 ′ of 1 to 80 °.
This is because when the irradiation angle width θ4 ′ is less than 1 °, the interval between the louver structures becomes too narrow, and it may be difficult to obtain a light diffusion film. On the other hand, if the irradiation angle width θ4 ′ exceeds 80 °, the irradiation light may be excessively dispersed and it may be difficult to form a louver structure.
Therefore, the irradiation angle width θ4 ′ of the irradiation angle θ4 is more preferably set to a value within the range of 2 to 45 °, and further preferably set to a value within the range of 5 to 20 °.
By using a linear light source, it is substantially parallel light when viewed from the axial direction of the linear light source, and non-parallel when viewed from a direction perpendicular to the axial direction of the linear light source. Irradiation light can be irradiated.

Moreover, as irradiation light, an ultraviolet-ray, an electron beam, etc. are mentioned, However, It is preferable to use an ultraviolet-ray.
This is because, in the case of an electron beam, the polymerization rate is very fast, so that the components (A) and (B) cannot be sufficiently phase-separated during the polymerization process, making it difficult to form a louver structure. Because. On the other hand, when compared with visible light or the like, ultraviolet rays are richer in variations such as ultraviolet curable resins that cure by irradiation, so that the range of selection of component (A) and component (B) can be expanded. This is because it can.
Moreover, as irradiation conditions of ultraviolet rays, the peak illuminance at the time of irradiation on the surface of the coating layer is set to a value within the range of 0.1 to 50 mW / cm ² , and the integrated light amount is sufficient for the coating layer to be sufficiently cured. It is preferable to do so.
In addition, it is also preferable to irradiate with ultraviolet rays in multiple stages so that the integrated light amount can sufficiently cure the coating layer.
Moreover, it is preferable that the coating layer formed on the process sheet is moved at a speed of 0.1 to 10 m / min to pass the ultraviolet irradiation part by the ultraviolet irradiation apparatus.
The reason for this is that mass productivity may be excessively reduced when the speed is less than 0.1 m / min. On the other hand, when the speed exceeds 10 m / min, the coating layer is hardened, in other words, faster than the formation of the louver structure, and the incident angle of ultraviolet rays to the coating layer changes greatly along the film thickness direction. This is because the louver structure may be insufficiently formed.
In addition, as shown in FIG.5 (c), the light-diffusion film 10 after a photocuring process will be in the state which can be finally used by peeling the process sheet | seat 2. FIG.

2. Film thickness Moreover, it is preferable to make the film thickness of a light-diffusion film into the value within the range of 100-500 micrometers.
The reason for this is that when the thickness of the light diffusing film is set to a value within such a range, the light diffusing film is not laminated, and even when applied to a reflective liquid crystal display device or the like as a single layer, This is because it is possible to efficiently use external light as a light source, and to prevent the occurrence of problems such as a decrease in the sharpness of the displayed image and the appearance of iris colors.
That is, when the film thickness is less than 100 μm, the length 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, which is sufficient. 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 film thickness of the 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.

3. Louver structure Moreover, as shown to Fig.7 (a)-(c), the light-diffusion film 10 of this invention is the plate-shaped area | region 12 derived from (A) component, and the plate-shaped area derived from (B) component. 14 and the louver structure that alternately extends, the widths (S1, S2) of the plate-like region 12 derived from the component (A) and the plate-like region 14 derived from the component (B) are set to 0. A value in the range of 1 to 15 μm is preferable.
This is because when the width is less than 0.1 μm, it may be difficult to exhibit light diffusibility regardless of the incident angle of incident light. On the other hand, when the width exceeds 15 μm, it may be difficult to show light diffusibility regardless of the incident angle of incident light.
Therefore, each width (S1, S2) of the plate-like region 12 derived from the component (A) and the plate-like region 14 derived from the component (B) is set to a value within the range of 0.5 to 10 μm. More preferably, the value is more preferably in the range of 1 to 5 μm.

Moreover, it is preferable to make initial inclination angle (theta) 5 in a louver structure into the value within the range of 0-80 degrees.
This is because it may be difficult to show the incident angle dependency when the initial inclination angle θ5 exceeds 80 °.
Therefore, the initial inclination angle θ5 in the louver structure is more preferably set to a value in the range of 0 to 50 °.
The initial inclination angle θ5 is a plate shape when the angle with respect to the normal of the film surface measured in a cross section when the film is cut in a plane perpendicular to the louver structure extending along the film surface direction is 0 °. It means the inclination angle (°) of the region.
More specifically, as shown in FIGS. 7A to 7B, the angle on the narrow side of the angles formed by the normal of the film surface on the incident light irradiation side and the louver is referred to. Note that, as shown in FIGS. 7A to 7B, 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.
Furthermore, the light diffusion film 10 of the present embodiment may have a louver structure (length L1 in the film thickness direction) formed in the entire film thickness direction as shown in FIG. As shown in FIG. 4, at least one of the upper end portion and the lower end portion of the film 10 may have a louver structure-unformed portion (length L2 in the film thickness direction).

In addition, the length L1 in the film thickness direction in the louver structure is preferably a value within the range of 50 to 500 μm, although it depends on the film thickness of the light diffusion film 10.
This is because when the length is less than 50 μm, incident light that travels straight through the louver structure increases, and it may be difficult to obtain sufficient incident angle dependency. On the other hand, when the length exceeds 500 μm, a loss such as light reflection or absorption may occur while passing through the louver structure.
Therefore, the length in the film thickness direction L1 in the louver structure 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 addition, the width L2 of the upper and lower end portions where the louver structure is not formed depends on the film thickness of the light diffusing film 10, but is generally preferably a value within a range of 0 to 200 μm, and within a range of 0 to 100 μm. It is preferably a value, and more preferably a value within the range of 0 to 50 μm.
Moreover, as shown in FIG.7 (c), it is also preferable that the louver structure is bent.
This is because the louver structure is bent, so that the incident light that goes straight through the louver structure can be reduced and the uniformity of light diffusion can be improved.
In addition, such a bent louver structure can be obtained by irradiating light while changing the irradiation angle of irradiation light when performing photocuring of the composition for a light diffusion film. And it greatly depends on the type of component (B).

Moreover, it is preferable to make the refractive index of the plate-shaped area | region derived from the (A) component in a louver structure into the value within the range of 1.5-1.7.
The reason for this is that when the refractive index of the plate-like region derived from the component (A) is less than 1.5, the difference from the refractive index of the plate-like region derived from the component (B) is too small, This is because it may be difficult to obtain the dependence on the incident angle. On the other hand, if the refractive index of the part derived from the component (A) exceeds 1.7, the compatibility with the component (B) may be excessively lowered.
Therefore, it is more preferable to set the refractive index of the plate-like region derived from the component (A) in the louver structure to a value in the range of 1.52 to 1.65, and a value in the range of 1.55 to 1.6. More preferably.
The refractive index can be measured according to JIS K0062, for example.

Moreover, it is preferable to make the refractive index of the plate-shaped area | region derived from the (B) component in a louver structure into the value within the range of 1.4-1.5.
This is because when the refractive index of the plate-like region derived from the component (B) has a value of 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 plate-like region derived from the component (B) is a value exceeding 1.5, the difference from the refractive index of the plate-like region derived from the component (A) becomes too small, and a desired value is obtained. This is because it may be difficult to obtain the incident angle dependency.
Accordingly, the refractive index of the plate-like region derived from the component (B) in the louver structure is more preferably set to a value within the range of 1.42 to 1.48, and the value within the range of 1.44 to 1.46. More preferably.
The refractive index can be measured according to JIS K0062, for example.

In the light diffusing film of this embodiment, the difference between the refractive index of the plate-like region derived from the component (A) in the louver structure and the refractive index of the plate-like region derived from the component (B) is 0. A value of 01 or more is preferable.
The reason for this is that 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. This is because it may become excessively narrow.
Therefore, the difference between the refractive index of the part derived from the component (A) in the louver structure and the refractive index of the part derived from the component (B) is more preferably 0.03 or more.
In addition, although the difference of refractive index is so preferable that it is large, about 0.1 is considered to be an upper limit.

4). Applications Further, as shown in FIG. 8, the light diffusion film of the present invention is preferably used for a reflective liquid crystal display device 100.
The reason for this is that the light diffusing film of the present invention can efficiently diffuse outside light so that it can be efficiently transmitted and taken into the liquid crystal display device, and that light can be used as a light source. This is because it can.
Therefore, the light diffusing film of the present invention is disposed on the upper surface or the lower surface of the liquid crystal cell 110 composed of the glass plates (104, 108) and the liquid crystal 106, and the specular reflector 107, etc. It is preferable to use as the light diffusion plate 103.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Example 1]
1. (B) Synthesis of component In a container, 2 mol of isophorone diisocyanate (IPDI) as component (a) with respect to 1 mol of polypropylene glycol (PPG) having a weight average molecular weight of 9,200 as component (b), And after accommodating 2 mol of 2-hydroxyethyl methacrylate (HEMA) as (c) component, it superposed | polymerized in accordance with the conventional method, and obtained the polyether urethane methacrylate of the weight average molecular weight 9,900.
In the following, the obtained polyether urethane methacrylate may be referred to as “PEUMA”.

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

2. Preparation of composition for light diffusing film Next, 100 parts by weight of polyether urethane methacrylate (refractive index: 1.46) having a weight average molecular weight of 9,900 as component (B) was obtained. O-phenylphenoxyethoxyethyl acrylate having a molecular weight of 268 represented by the following formula (4) (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A-LEN-10, refractive index 1.58), 100 parts by weight, and component (C) After adding 10 parts by weight of phenylglyoxylic acid methyl ester (BASF Japan Co., Ltd., Darocur MBF) represented by the following formula (6) as follows, the mixture is heated and mixed at 80 ° C. to form a light diffusion film A composition was obtained. In addition, the refractive indexes of the component (A) and the component (B) were measured according to JIS K0062 using an Abbe refractometer [manufactured by Atago Co., Ltd., product name “Abbe refractometer DR-M2”, Na light source, wavelength: 589 nm].
Hereinafter, o-phenylphenoxyethoxyethyl acrylate may be referred to as “A-LEN-10” and phenylglyoxylic acid methyl ester may be referred to as “Darocur MBF”.
The absorption maximum wavelengths of phenylglyoxylic acid methyl ester were 255 nm and 325 nm.

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

4). Next, a UV irradiation apparatus (ECS-4011GX, manufactured by Eye Graphics Co., Ltd.) 20 in which a condensing cold mirror 22 is attached to a linear high-pressure mercury lamp 25 as shown in FIG. 6 is prepared. did.
Next, the light shielding plate 21 is installed on the heat ray cut filter frame, and the normal direction of the laminate composed of the coating layer and the PET when the ultraviolet rays applied to the surface of the coating layer 1 are viewed from the longitudinal direction is 0 °. In this case, the irradiation angle of direct ultraviolet rays from the lamp 25 (θ4 in FIG. 6B) was set in a range of 0 to 10 ° (irradiation angle width θ4 ′ = 10 °).
At this time, the height of the lamp from the coating layer 1 was set to 290 mm, and the peak illuminance on the coating layer surface was set to 9 mW / cm ² .
The illuminance described above was measured by installing a UV METER eye ultraviolet ray integrating illuminometer “UVPF-A1” manufactured by Eye Graphics Co., Ltd., to which the light receiver was attached, at the position of the coating layer.
In addition, in order to prevent the reflected light from the light shielding plate 21 and the like from becoming stray light inside the irradiator and affecting the photocuring of the coating layer 1, a light shielding plate is also provided in the vicinity of the conveyor, and ultraviolet rays emitted directly from the lamp 25. Only the coating layer 1 was set to be irradiated.
Next, the coating layer 1 was moved by the conveyor in the right direction in FIG. 6 at a speed of 0.2 m / min while irradiating with ultraviolet rays under the above-mentioned setting conditions to obtain a light diffusion film having a film thickness of 250 μm. .
In addition, the film thickness of the light-diffusion film was measured using the constant-pressure thickness measuring device (Takara Seisakusho Co., Ltd. product, Teclock PG-02J).
Further, when the cross section of the light diffusing film was observed with an optical digital microscope (manufactured by Keyence Corp.), the inclination angle θ5 (initial inclination angle) of the louver structure on the film surface side where the irradiated light first hits was −6.5 °. The length of the louver structure in the film thickness direction (L1 in FIG. 7B) was 200 μm.

5. Measurement Using a variable angle colorimeter (VC-2, manufactured by Suga Test Instruments Co., Ltd.), incident on the film from above the obtained light diffusion film, as shown in FIG. 9A. Light was incident at an angle θ1 = 20 ° (C light source, viewing angle 2 °).
Next, the spread of diffused light diffused by the light diffusion film and the distribution of its brightness (%) were measured. The measurement result is shown on the horizontal axis where the value of the vertical axis of the scatter diagram shown in FIG. 9C is 0 °.
That is, the value on the horizontal axis indicates the range of the opening angle (°) in the major axis direction in light diffusion, and the color of the plot indicates the lightness (%) of diffused light diffused at that angle.
Here, the relationship between the color of the plot and the lightness (%) indicates that if the color of the plot is red, it indicates a value of 10% or higher in lightness, orange, bright yellow, yellow, yellowish green, green, It indicates that the brightness is close to 0% in the order of light blue, blue, dark blue, and amber. Details are shown in FIG. 9B.
Furthermore, the incident light on the surface of the light diffusing film is fixed in a state where the incident light is fixed in order to measure the distribution of the opening angle (°) in the minor axis direction and the brightness (%) in the light diffusion. The same measurement was performed while rotating the light diffusion film in the range of −80 to 80 ° in the same plane with the incident point of. The angle of rotation means the angle of rotation when the angle of the first light diffusion film at the time of measurement described above is 0 °. For example, the measurement result when the light diffusing film is rotated by 20 ° is shown on the horizontal axis where the value of the vertical axis of the scatter diagram shown in FIG. 9C is 20 °.
Accordingly, in the scatter diagram shown in FIG. 9C, the region where the diffused light having a lightness of 10% or more is distributed is a region surrounded by a dotted line in FIG. 9C. The obtained result is shown in FIG. Also, the major axis direction opening angle θ2 and minor axis direction opening angle θ3 in light diffusion when θ1 = 20 ° (calculated based on the maximum width in each direction of the region where the brightness of the diffused light is 10% or more) are shown. It is shown in 1.

  Next, in the light diffusing film of Example 1, the incident light angle θ1 was changed to 0 °, 10 °, 30 °, and 40 °, respectively, and the major axis in light diffusion was the same as in the case of the incident angle θ1 = 20 °. The opening angle θ2 in the direction and the opening angle θ3 in the minor axis direction were measured. The obtained results are shown in FIGS.

[Example 2]
In Example 2, a light diffusing film composition and a light diffusing film were produced and evaluated in the same manner as in Example 1 except that the amount of component (C) added was changed to 20 parts by weight.
However, in Example 2, evaluation was not performed when the incident angle θ1 was changed to a value other than 20 ° as in Example 1. The same applies to Examples 3 to 7 and Comparative Examples 1 to 4. The obtained results are shown in FIG.

[Example 3]
In Example 3, a composition for a light diffusion film and a light diffusion film were produced and evaluated in the same manner as in Example 1 except that the amount of component (C) added was changed to 4 parts by weight. The obtained results are shown in FIG.

[Example 4]
In Example 4, a composition for a light diffusion film and a light diffusion film were produced and evaluated in the same manner as in Example 1 except that the amount of component (C) added was changed to 2 parts by weight. The obtained results are shown in FIG.

[Example 5]
In Example 5, the amount of the component (C) was changed to 5 parts by weight, and 2-hydroxy-2-methylpropionphenone (BASF Japan Ltd.) represented by the following formula (7) was used as another photopolymerization initiator. ), Darocur 1173) A light diffusing film composition and a light diffusing film were produced and evaluated in the same manner as in Example 1 except that 5 parts by weight were added. The obtained results are shown in FIG.
Hereinafter, 2-hydroxy-2-methylpropionphenone is sometimes referred to as “Darocur 1173”.

[Example 6]
In Example 6, the composition for light diffusing film and light were the same as in Example 1 except that the component (A) was changed to o-phenylphenoxyethoxyethyl acrylate having a weight average molecular weight of 312 represented by the following formula (5). Diffusion films were manufactured and evaluated. The obtained results are shown in FIG.
In the following, o-phenylphenoxyethoxyethyl acrylate may be referred to as “A′-LEN-10”.

[Example 7]
In Example 7, the composition for a light diffusing film and the component (A) were the same as in Example 1 except that the component (A) was a 50:50 (weight ratio) mixture of A-LEN-10 and A′-LEN-10. A light diffusing film was manufactured and evaluated. The obtained results are shown in FIG.

[Comparative Example 1]
In Comparative Example 1, the arylglyoxylate ester compound represented by the general formula (1) as the component (C) was not added, but 10 parts by weight of Darocur 1173 was added as a different photopolymerization initiator. In the same manner as in Example 1, a composition for light diffusion film and a light diffusion film were produced and evaluated. The obtained results are shown in FIG.

[Comparative Example 2]
In Comparative Example 2, a composition for a light diffusion film and a light diffusion film were produced and evaluated in the same manner as in Comparative Example 1, except that the amount of Darocur 1173 added was changed to 20 parts by weight. The obtained results are shown in FIG.

[Comparative Example 3]
In Comparative Example 3, a composition for a light diffusing film and a light diffusing film were produced and evaluated in the same manner as in Comparative Example 1, except that the amount of Darocur 1173 added was changed to 4 parts by weight. The obtained results are shown in FIG.

[Comparative Example 4]
In Comparative Example 4, a composition for a light diffusing film and a light diffusing film were produced and evaluated in the same manner as in Comparative Example 1, except that the amount of Darocur 1173 added was changed to 2 parts by weight. The obtained results are shown in FIG.

[Comparative Example 5]
In Comparative Example 5, without adding the component (C), as other photopolymerization initiator, 1-hydroxy-cyclohexyl-phenyl-ketone represented by the following formula (8) (manufactured by BASF Japan Ltd., Irugacure 184) The composition for light diffusion film and the light diffusion film were produced and evaluated in the same manner as in Example 1 except that 10 parts by weight) was added. The obtained results are shown in FIG.
In the following, 1-hydroxy-cyclohexyl-phenyl-ketone may be referred to as “Irugacure 184”.

[Comparative Example 6]
In Comparative Example 6, without adding the component (C), 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopro represented by the following formula (9) was used as another photopolymerization initiator. A composition for a light diffusion film and a light diffusion film were produced and evaluated in the same manner as in Example 1 except that 10 parts by weight of pan-1-one (manufactured by BASF Japan Ltd., Irugacure 907) was added. The obtained results are shown in FIG.
Hereinafter, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one may be referred to as “Irugacure 907”.

As described above in detail, according to the present invention, a high refractive index polymerizable compound, a low refractive index polymerizable compound, and an arylglyoxylate ester compound having a specific structure as a photopolymerization initiator, By blending, it was possible to obtain a light diffusion film that effectively expanded the opening angle in the minor axis direction while maintaining the opening angle in the major axis direction in light diffusion.
More specifically, it has a good incident angle dependency in transmission and diffusion of light, a wide light diffusion incident angle region, and an opening angle in the minor axis direction while maintaining a major axis opening angle in light diffusion. In addition, it has become possible to obtain a light diffusion film that is effectively enlarged.
Therefore, the composition for a light diffusion film of the present invention can be applied to a viewing angle control film, a viewing angle widening film, and a projection screen in addition to a light control film in a reflective liquid crystal display device. It is expected to contribute significantly to the improvement of quality.

1: coating layer, 2: process sheet, 10: light diffusion film, 12: cured product (plate-like region) having a relatively high refractive index derived from component (A), 14: relatively derived from component (B) Cured material having a low refractive index (plate-like region), 20: UV irradiation device, 21: heat ray cut filter, 22: cold mirror, 23: light shielding plate, 25: linear UV lamp, 50 (52, 54, 56) : Incident light (active energy ray), 100: reflection type liquid crystal display device, 101: polarizing plate, 102: retardation plate, 103: light diffusion plate, 104: glass plate, 105: color filter, 106: liquid crystal, 107: Specular reflector, 108: Glass plate, 110: Liquid crystal cell

Claims (9)

A composition for a light diffusing film comprising a high refractive index polymerizable compound as component (A), a low refractive index polymerizable compound as component (B), and a photopolymerization initiator as component (C). ,
The photopolymerization initiator as the component (C) is an aryl glyoxylate ester compound represented by the following general formula (1).

(In General Formula (1), R < ¹ > -R < ⁵ > is respectively independent, a hydrogen atom, a hydroxyl group, a carboxyl group, a C1-C10 alkyl group, a C1-C10 alkoxy group, and C1-C1 A halogenated alkyl group having 1 to 10 carbon atoms, a hydroxyalkyl group having 1 to 10 carbon atoms, a carboxyalkyl group having 1 to 10 carbon atoms in the alkyl group, and a halogen atom, and R ⁶ is a carbon atom having 1 carbon atom. -10 alkyl group or C6-20 aryl group.)   The blending amount of the component (A) is set to a value within the range of 25 to 400 parts by weight with respect to 100 parts by weight of the component (B), and the blending amount of the component (C) is changed to the component (A). The light diffusion film according to claim 1, wherein the light diffusion film has a value within a range of 2 to 20 parts by weight with respect to a total amount (100 parts by weight) of the component and the component (B).   The composition for a light diffusing film according to claim 1 or 2, wherein the maximum absorption wavelength of the component (C) is set to a value within a range of 240 to 340 nm. In Formula (1), together with R ¹ to R ⁵ is a hydrogen atom, R ⁶ is according to any one of claims 1 to 3, wherein an alkyl group having 1 to 4 carbon atoms A composition for a light diffusion film. The component (A) is a biphenyl compound represented by the following general formula (2), and the component (B) is a polymerizable compound having a weight average molecular weight in the range of 3,000 to 20,000. It exists, The composition for light-diffusion films as described in any one of Claims 1-4 characterized by the above-mentioned.

(In the general formula (2), R ^{7 to} R ¹⁶ are each independent, and at least one of R ^{7 to} R ¹⁶ is a substituent represented by the following general formula (3), and the rest is hydrogen. It is a substituent of any one of an atom, a hydroxyl group, a carboxyl group, an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, a carboxyalkyl group and a halogen atom.)

(In General Formula (3), R ¹⁷ is a hydrogen atom or a methyl group, carbon number n is an integer of 1 to 4, and repetition number m is an integer of 1 to 10.)   The said (B) component is urethane (meth) acrylate, The composition for light-diffusion films as described in any one of Claims 1-5 characterized by the above-mentioned.   The light according to claim 1, wherein the difference between the refractive index of the component (A) and the refractive index of the component (B) is 0.01 or more. Composition for diffusion film. A light diffusion film formed by irradiating an active energy ray to a composition for a light diffusion film and curing it,
The composition for a light diffusion film contains a high refractive index polymerizable compound as the component (A), a low refractive index polymerizable compound as the component (B), and a photopolymerization initiator as the component (C). A light diffusing film, wherein the photopolymerization initiator as the component (C) is an arylglyoxylate ester compound represented by the following general formula (1).

(In General Formula (1), R < ¹ > -R < ⁵ > is respectively independent, a hydrogen atom, a hydroxyl group, a carboxyl group, a C1-C10 alkyl group, a C1-C10 alkoxy group, and C1-C1 A halogenated alkyl group having 1 to 10 carbon atoms, a hydroxyalkyl group having 1 to 10 carbon atoms, a carboxyalkyl group having 1 to 10 carbon atoms in the alkyl group, and a halogen atom, and R ⁶ is a carbon atom having 1 carbon atom. -10 alkyl group or C6-20 aryl group.)   The light diffusion film according to claim 8, wherein the film thickness is set to a value within a range of 100 to 500 μm.