JP2017187770A - Anisotropic optical film and production method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic optical film that improves a transmittance in a transmissive region and enlarges a diffusion angle range in an MD direction compared to a pillar structure and enlarges a diffusion angle range in a TD direction compared to a louver structure and that can eliminate drastic changes in luminance or glare.SOLUTION: An anisotropic optical film 100 comprises at least an anisotropic light diffusion layer 110 in which a linear transmittance varies depending on an angle of incident light. The anisotropic light diffusion layer 110 has a matrix region 111, a plurality of first columnar structures 113 and a plurality of second columnar structures 123, in which the first columnar structures 113 are configured to orient from one surface of the anisotropic light diffusion layer 110 to the other surface, and the second columnar structures 123 are configured to orient from a position over 20% of the layer thickness of the anisotropic light diffusion layer from the one surface of the anisotropic light diffusion layer 110 to the other surface.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an anisotropic optical film in which the diffusibility of transmitted light changes according to an incident light angle, and a method for manufacturing the same.

  A member having light diffusibility (light diffusing member) is used in a display device in addition to a lighting fixture and a building material. Examples of the display device include a liquid crystal display device (LCD) and an organic electroluminescence element (organic EL). As the light diffusion expression mechanism of the light diffusing member, scattering due to unevenness formed on the surface (surface scattering), scattering due to a refractive index difference between the matrix resin and fine particles dispersed therein (internal scattering), and surface scattering This is due to both internal scattering. However, these light diffusing members generally have isotropic diffusion performance, and even if the incident light angle is slightly changed, the diffusion characteristics of the transmitted light are not greatly different.

  On the other hand, there is an anisotropic optical film in which incident light in a certain angle region is strongly diffused and incident light at other angles is transmitted, that is, the amount of linear transmitted light can be changed according to the incident light angle. Are known. As such an anisotropic optical film, an assembly of a plurality of rod-like cured regions extending in parallel with a predetermined direction P inside a resin layer made of a cured product of a composition containing a photopolymerizable compound. An anisotropic diffusion medium having a body is disclosed (for example, see Patent Document 1). In the following, in this specification, the structure of an anisotropic optical film in which an assembly of a plurality of rod-shaped cured regions extending in parallel with a predetermined direction P as described in Patent Document 1 is formed. This is called “pillar structure”.

  In such an anisotropic optical film having a pillar structure, when light is incident on the film from above to below, the flow direction in the film manufacturing process (hereinafter referred to as “MD direction”). The film shows the same diffusion in the width direction of the film perpendicular to the MD direction (hereinafter referred to as “TD direction”). That is, the diffusion in the anisotropic optical film having a pillar structure is isotropic. Therefore, in an anisotropic optical film having a pillar structure, a rapid change in brightness and glare are unlikely to occur.

  On the other hand, as an anisotropic optical film, an anisotropic film in which an aggregate of one or a plurality of plate-like cured regions is formed inside a resin layer made of a cured product of a composition containing a photopolymerizable compound, instead of the pillar structure. By using a diffractive optical film (see, for example, Patent Document 2), the linear transmittance in the non-diffusion region can be improved and the diffusion width can be widened. Hereinafter, in this specification, the structure of an anisotropic optical film in which an aggregate of one or a plurality of plate-like cured regions as described in Patent Document 2 is referred to as a “louver structure”. .

  On the other hand, it solves the problem of the anisotropic optical film with the pillar structure and the anisotropic optical film with the louver structure, has a good incident light angle dependency in light transmission and diffusion, and reduces the width of the diffusion region. For example, Patent Document 3 discloses an anisotropic optical film in which an anisotropic light diffusion layer having a pillar structure (corresponding to the “column structure” in Patent Document 3) and an anisotropic light diffusion layer having a louver structure are laminated. Has been.

JP 2005-265915 A Japanese Patent No. 4802707 JP 2012-141593 A

  However, the anisotropic optical film having a pillar structure has a low linear transmittance in a non-diffusive region, which is an incident light angle range having a high linear transmittance, and an incident light angle range having a low linear transmittance (ie, a high diffusion intensity). There is a problem that the width of the diffusion region (diffusion width) is narrow.

  Further, in the anisotropic optical film having the louver structure, when light is incident on the film from the upper side to the lower side, the diffusion is different in the MD direction and the TD direction. That is, the diffusion in the anisotropic optical film having a louver structure exhibits anisotropy. Specifically, for example, if the width of the diffusion region (diffusion width) is wider than the pillar structure in the MD direction, the diffusion width is narrower than the pillar structure in the TD direction. Therefore, in the anisotropic optical film having a louver structure, for example, when the diffusion width is narrowed in the TD direction, a sharp change in luminance occurs in the TD direction, and as a result, light interference is likely to occur and glare is likely to occur. is there.

  However, conventional anisotropic optical films cannot solve the following problems. That is, in the pillar structure, the transmittance of the non-diffusion region is low and the diffusion region is isotropic, and in the louver structure, the transmittance of the non-diffusion region is high. Furthermore, in the louver structure, diffusion in the MD direction is wider than that in the pillar, but the diffusion region in the TD direction is narrow, and a rapid change in luminance occurs in the TD direction, causing light interference and glare. .

  Further, in the anisotropic optical film described in Patent Document 3 in which an anisotropic light diffusion layer having a pillar structure and an anisotropic light diffusion layer having a louver structure are laminated, a sudden change in brightness or glare may occur. . Furthermore, since a step of laminating an anisotropic light diffusion layer having a pillar structure and an anisotropic light diffusion layer having a louver structure is essential, productivity may be inferior.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an anisotropic optical film that compensates for the respective disadvantages of the pillar structure and the louver structure. That is, the transmittance of the non-diffusion region is improved as compared with the pillar structure, and the diffusion angle range in the MD direction is expanded, and the diffusion angle range in the TD direction is also expanded as compared with the louver structure, and the brightness is rapidly changed. It is an object to provide an anisotropic optical film that can solve the problems such as glaring and glare.

  The present inventors have intensively studied and found that the above problems can be solved by an anisotropic optical film having a specific structure, and have completed the present invention. That is, the present invention is as follows.

The present invention (1)
An anisotropic optical film having at least an anisotropic light diffusing layer whose linear transmittance varies depending on the incident light angle,
The anisotropic optical film has a matrix region, a plurality of first columnar structures (for example, columnar regions 113), and a plurality of second columnar structures (for example, columnar regions 123),
The first columnar structure is configured by being oriented from one surface of the anisotropic light diffusion layer to the other surface,
The second columnar structure is configured to be oriented from the one surface of the anisotropic light diffusion layer to the other surface from a position exceeding 20% of the thickness of the anisotropic light diffusion layer. It is an anisotropic optical film characterized.
The present invention (2)
In one of the first columnar structure and the second columnar structure, the aspect ratio between the average minor axis and the average major axis is 2 or more,
An anisotropic optical film according to the invention (1), wherein an aspect ratio between an average minor axis and an average major axis in the other of the first columnar structure and the second columnar structure is less than 2. It is.
The present invention (3)
The average minor axis and the average major axis in one of the first columnar structure and the second columnar structure are 0.5 μm to 5.0 μm and 1 μm to 100 μm, respectively.
In the other of the first columnar structure and the second columnar structure, an average minor axis and an average major axis are 0.5 μm to 5.0 μm and 0.5 μm to 8.0 μm, respectively, It is an anisotropic optical film of invention (1) or (2).
The present invention (4)
The anisotropic optical film according to any one of the inventions (1) to (3), wherein the anisotropic light diffusion layer has a thickness of 10 μm to 200 μm.
The present invention (5)
The anisotropic optical film according to any one of the inventions (1) to (4), wherein the anisotropic optical film has a maximum linear transmittance of 30% or more and less than 80%.
The present invention (6)
The invention (1), wherein an absolute value of a difference between a scattering center axis angle of the first columnar structure and a scattering center axis angle of the second columnar structure is 0 ° to 30 °. It is an anisotropic optical film in any one of-(5).
The present invention (7)
Anisotropic optics according to any one of the inventions (1) to (6), wherein the MD direction diffusion width is 30 ° or more and less than 70 °, and the TD direction diffusion width is 10 ° or more and less than 30 °. It is a film.
The present invention (8)
On the base material, a coating process for coating the anisotropic light diffusion layer forming composition and providing a coating film;
Curing by irradiation of light from above the coating film, a first structure forming step,
After the first structure forming step, including a second structure forming step of continuously curing by irradiation with light rays,
Of the first structure forming step and the second structure forming step, one step is cured by irradiation with a unidirectional diffused light, and the other step is cured by irradiation with parallel light. The manufacturing method of the anisotropic optical film in any one of said invention (1)-(7).
The present invention (9)
The one-way diffused light in the first structure forming step or the second structure forming step is a diffused light obtained via a directional diffusion element, and the aspect ratio of the diffused light is 2 or more The manufacturing method according to the invention (8), characterized in that it is a feature.

  According to the anisotropic optical film of the present invention, it is possible to compensate for the respective disadvantages of the pillar structure and the louver structure, and the transmittance of the non-diffusing region is improved and the diffusion angle in the MD direction is improved as compared with the pillar structure. Compared with the louver structure, the range can be expanded and the diffusion angle range in the TD direction can be expanded, and a sudden change in brightness and glare can be eliminated. In addition, since the defects of both structures can be compensated without stacking layers, the productivity is also excellent.

It is a schematic diagram which shows an example of the structure of the anisotropic optical film which has a columnar area | region of a pillar structure and a louver structure, and the mode of the transmitted light which injected into these anisotropic optical films. It is explanatory drawing which shows the evaluation method of the light diffusibility of an anisotropic optical film. It is a graph which shows the relationship between the incident light angle to the anisotropic optical film of a pillar structure and a louver structure shown in FIG. 1, and a linear transmittance | permeability. It is a graph for demonstrating a diffusion area | region and a non-diffusion area | region. It is a perspective view which shows an example of the structure of the anisotropic light-diffusion layers 110 and 120 in the anisotropic optical film 100 which concerns on this form. FIG. 4 is a plan view A showing an example of the configuration of an anisotropic light diffusion layer having a louver structure, and a plan view B showing an example of the configuration of an anisotropic light diffusion layer having a hybrid structure. It is a perspective view which shows an example of the structure of the anisotropic light-diffusion layers 210 and 220 in the aspect of the anisotropic optical film 200. FIG. FIG. 4 is a plan view A showing an example of the configuration of an anisotropic light diffusion layer having a louver structure in an embodiment of the anisotropic optical film 200, and a plan view B showing an example of the configuration of an anisotropic light diffusion layer having a hybrid structure. 3 is a perspective view showing an example of the configuration of anisotropic light diffusion layers 310 and 320 in an embodiment of an anisotropic optical film 300. FIG. FIG. 6 is a plan view A illustrating an example of the configuration of an anisotropic light diffusion layer having a pillar structure in an embodiment of the anisotropic optical film 300, and a plan view B illustrating an example of the configuration of an anisotropic light diffusion layer having a hybrid structure. It is a schematic diagram which shows the outline of the columnar area | region 213 and 223 which grows according to the manufacturing process of the anisotropic optical film 200. FIG. It is a schematic diagram which shows the outline of the columnar area | regions 313 and 323 which grow according to the manufacturing process of the anisotropic optical film 300. FIG. It is a three-dimensional polar coordinate display for demonstrating the scattering center axis | shaft in an anisotropic light-diffusion layer. It is a cross-sectional photograph of MD direction and TD direction of the anisotropic optical film which concerns on Example 4. FIG. It is a cross-sectional photograph of MD direction and TD direction of the anisotropic optical film which concerns on Example 10. FIG. It is a graph for demonstrating the evaluation method of the rapid change of the brightness | luminance of the anisotropic optical film of an Example and a comparative example.

<<< Definition of main terms >>>
The “low refractive index region” and the “high refractive index region” are regions formed by the difference in local refractive index of the material constituting the anisotropic optical film according to the present invention, compared to the other. It is a relative value indicating whether the refractive index is low or high. These regions are formed when the material forming the anisotropic optical film is cured.

  The “scattering center axis” is a direction in which the light diffusibility coincides with the incident light angle of light having a substantially symmetrical shape with respect to the incident light angle when the incident light angle to the anisotropic optical film is changed. means. “Substantially symmetrical” means that when the scattering center axis is inclined with respect to the normal direction of the film, the optical characteristics (“optical profile” described later) are not strictly symmetrical. Because. The scattering center axis should be confirmed by observing the inclination of the cross section of the anisotropic optical film with an optical microscope or by observing the projected shape of light through the anisotropic optical film while changing the incident light angle. Can do.

The linear transmittance generally relates to the linear transmittance of light incident on the anisotropic optical film. When the light is incident from a certain incident light angle, the transmitted light amount in the linear direction, the light amount of the incident light, and The ratio is expressed by the following formula.
Linear transmittance (%) = (Linear transmitted light amount / incident light amount) × 100

  In the present invention, both “scattering” and “diffusion” are used without distinction, and both indicate the same meaning. Furthermore, the meaning of “photopolymerization” and “photocuring” means that a photopolymerizable compound undergoes a polymerization reaction with light, and both are used synonymously.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that in the present specification and drawings, components having the same reference numerals have substantially the same structure or function.

<<< Structure and Properties of Anisotropic Optical Film >>>
As a premise for explaining the anisotropic optical film according to this embodiment with reference to FIGS. 1 to 4, a single-layer anisotropic optical film according to the prior art (an “anisotropic light diffusion layer” referred to in this embodiment is one layer) The structure and characteristics of the anisotropic optical film in the case of only the case will be described.

  FIG. 1 is a schematic diagram showing an example of the structure of a single-layer anisotropic optical film having columnar regions having a pillar structure and a louver structure, and the state of transmitted light incident on these anisotropic optical films. FIG. 2 is an explanatory diagram showing a method for evaluating the light diffusibility of an anisotropic optical film. FIG. 3 is a graph showing the relationship between the incident light angle and the linear transmittance on the anisotropic optical film having the pillar structure and the louver structure shown in FIG. FIG. 4 is a graph for explaining a diffusion region and a non-diffusion region.

<< Basic structure of anisotropic optical film >>
An anisotropic optical film is a film in which a region having a refractive index different from the matrix region of the film is formed in the film thickness direction. The shape of the regions having different refractive indexes is not particularly limited. For example, as shown in FIG. 1A, the matrix region 11 has a columnar shape (for example, a rod shape) having a minor axis and a minor axis with a small aspect ratio. ) Formed in the anisotropic optical film (pillar structure anisotropic optical film) 10 in which the columnar regions 13 having different refractive indexes are formed, and in the matrix region 21 as shown in FIG. There is an anisotropic optical film (an anisotropic optical film having a louver structure) 20 in which columnar regions 23 having different refractive indexes formed in a columnar shape (for example, substantially plate shape) having a large aspect ratio are formed.

<< Characteristics of Anisotropic Optical Film >>
The anisotropic optical film having the above-described structure is a light diffusing film having different light diffusibility depending on an incident light angle to the film, that is, a light diffusing film having an incident light angle dependency. The light incident on the anisotropic optical film at a predetermined incident light angle is aligned with the orientation direction of the regions having different refractive indexes (for example, the extending direction (orientation direction) of the columnar region 13 in the pillar structure or the plate-like region in the louver structure). In the case of being substantially parallel to the height direction of 23, diffusion is given priority, and in the case of being not parallel to that direction, transmission is given priority.

  Here, the light diffusibility of the anisotropic optical film will be described more specifically with reference to FIGS. Here, the light diffusibility of the anisotropic optical film 10 having the above-described pillar structure and the anisotropic optical film 20 having the louver structure will be described as an example.

  The light diffusibility evaluation method is performed as follows. First, as shown in FIG. 2, the anisotropic optical films 10 and 20 are disposed between the light source 1 and the detector 2. In this embodiment, the incident light angle 0 is set when the irradiation light I from the light source 1 is incident from the normal direction of the anisotropic optical films 10 and 20. The anisotropic optical films 10 and 20 are arranged so as to be able to be arbitrarily rotated around the straight line L, and the light source 1 and the detector 2 are fixed. That is, according to this method, the sample (anisotropic optical films 10 and 20) is arranged between the light source 1 and the detector 2, and the sample advances straight while changing the angle with the straight line L of the sample surface as the central axis. The linear transmittance that passes through and enters the detector 2 can be measured.

  The anisotropic optical films 10 and 20 were each evaluated for light diffusibility when the TD direction in FIG. 1 (the axis in the width direction of the anisotropic optical film) was selected as the straight line L of the rotation center shown in FIG. The evaluation results of the obtained light diffusibility are shown in FIG. FIG. 3 shows the incident light angle dependency of the light diffusibility (light scattering property) of the anisotropic optical films 10 and 20 shown in FIG. 1 measured using the method shown in FIG. The vertical axis in FIG. 3 indicates the linear transmittance that is an index indicating the degree of scattering (in this embodiment, when a parallel light beam having a predetermined light amount is incident, the light amount of the parallel light beam emitted in the same direction as the incident direction is shown. Ratio, more specifically, linear transmittance = detected light amount of detector 2 when anisotropic optical films 10 and 20 are present / detected light amount of detector 2 when anisotropic optical films 10 and 20 are not present) The horizontal axis represents the incident light angle to the anisotropic optical films 10 and 20. The solid line in FIG. 3 indicates the light diffusibility of the anisotropic optical film 10 having a pillar structure, and the broken line indicates the light diffusibility of the anisotropic optical film 20 having a louver structure. In addition, the positive / negative of the incident light angle has shown that the direction which rotates the anisotropic optical films 10 and 20 is reverse.

  As shown in FIG. 3, the anisotropic optical films 10 and 20 have light diffusivity that depends on the incident light angle and the linear transmittance changes depending on the incident light angle. Here, as shown in FIG. 3, a curve indicating the dependence of the light diffusivity on the incident light angle is hereinafter referred to as “optical profile”. The optical profile does not directly express the light diffusivity, but if it is interpreted that the diffuse transmittance increases due to the decrease of the linear transmittance, the optical profile generally shows the light diffusibility. It can be said that. In a normal isotropic light diffusion film, a peak-shaped optical profile having a peak near 0 ° is shown, but in the anisotropic optical films 10 and 20, the central axis (thickness) direction of the columnar regions 13 and 23, That is, the linear transmittance is minimal once at an incident light angle of ± 5 to 10 °, compared with the linear transmittance when incident in the scattering central axis direction (the incident light angle in this direction is 0 °). The linear transmittance increases as the incident light angle (absolute value thereof) increases, and shows a valley-shaped optical profile in which the linear transmittance reaches a maximum value at an incident light angle of ± 45 to 60 °. Thus, in the anisotropic optical films 10 and 20, the incident light is strongly diffused in the incident light angle range of ± 5 to 10 ° close to the scattering central axis direction, but is diffused in the incident light angle range higher than that. It has the property of weakening and increasing the linear transmittance. Hereinafter, the angle range of two incident light angles with respect to the linear transmittance that is an intermediate value between the maximum linear transmittance and the minimum linear transmittance is referred to as a diffusion region (the width of the diffusion region is referred to as a “diffusion width”), and other incident light is incident. The light angle range is referred to as a non-diffusion region (transmission region). Here, referring to FIG. 4, the diffusion region and the non-diffusion region will be described by taking the anisotropic optical film 20 having a louver structure as an example. FIG. 4 shows an optical profile of the anisotropic optical film 20 having the louver structure of FIG. 3. As shown in FIG. 4, the maximum linear transmittance (in the example of FIG. 78%) and the minimum linear transmittance (in the example of FIG. 4, the linear transmittance is about 6%), the two incidents to the linear transmittance (in the example of FIG. 4, the linear transmittance is about 42%) The incident light angle range between the light angles (inside the two incident light angles at the positions of the two black spots on the optical profile shown in FIG. 4) is a diffusion region, and the other (two on the optical profile shown in FIG. The incident light angle range outside the two incident light angles at the position of the black spot is a non-diffusing region.

  In the anisotropic optical film 10 having the pillar structure, as can be seen from the state of the transmitted light in FIG. 1B, the transmitted light has a substantially circular shape, and the MD direction and the TD direction have substantially the same light. It shows diffusivity. That is, in the anisotropic optical film 10 having a pillar structure, diffusion is isotropic. Further, as shown by the solid line in FIG. 3, since the change in light diffusivity (particularly, the optical profile near the boundary between the non-diffusing region and the diffusing region) is relatively gradual even when the incident light angle is changed, It has the effect of preventing sudden changes and glare. However, the anisotropic optical film 10 has a low linear transmittance in the non-diffusing region, as can be seen by comparing with the optical profile of the anisotropic optical film 20 having the louver structure shown by the broken line in FIG. There is also a problem that characteristics (luminance, contrast, etc.) are slightly lowered. Further, the anisotropic optical film 10 having a pillar structure has a problem that the width of the diffusion region is narrower than that of the anisotropic optical film 20 having a louver structure.

  On the other hand, in the anisotropic optical film 20 having the louver structure, as can be seen from the state of the transmitted light in FIG. 1A, the transmitted light has a substantially needle shape, and is transmitted in the MD direction and the TD direction. Diffusivity varies greatly. That is, in the anisotropic optical film 20 having a louver structure, diffusion has anisotropy. Specifically, in the example illustrated in FIG. 1, diffusion is wider in the MD direction than in the case of the pillar structure, but diffusion is narrower in the TD direction than in the case of the pillar structure. In addition, as shown by the broken line in FIG. 3, when the incident light angle is changed (in the case of this embodiment, in the TD direction), the light diffusibility (in particular, the optical profile near the boundary between the non-diffusing region and the diffusing region) changes. Therefore, when the anisotropic optical film 20 is applied to a display device, a sharp change in brightness or glare appears, which may reduce visibility. In addition, the anisotropic optical film having a louver structure also has a problem that light interference (rainbow) is likely to occur. However, the anisotropic optical film 20 has an effect that the linear transmittance in the non-diffusion region is high and display characteristics can be improved.

<<< Configuration of Anisotropic Optical Film According to this Embodiment >>>
The structure of the anisotropic optical film 100 according to this embodiment will be described with reference to FIG. FIG. 5 is a perspective view showing an example of the configuration of the anisotropic light diffusion layers 110 and 120 in the anisotropic optical film 100 according to this embodiment. In the following, when the anisotropic optical film 100 is used, the anisotropic light diffusion layer having the anisotropic light diffusion layers 110 and 120 may be simply shown.

<< Overall structure >>
As shown in FIG. 5, the anisotropic optical film 100 is an anisotropic optical film having two anisotropic light diffusion layers 110 and 120 whose linear transmittance changes depending on the incident light angle. The two anisotropic light diffusion layers 110 and 120 are formed continuously (the anisotropic light diffusion layers 110 and 120 are conceptually different names, but are continuous layers as one layer). Here, the thickness of the anisotropic optical film 100 is the total thickness of the anisotropic diffusion layers 110 and 120.

  The anisotropic light diffusion layer 110 includes a matrix region 111 and a plurality of columnar regions 113 (first columnar structures) having a refractive index different from that of the matrix region 111. The anisotropic light diffusion layer 120 includes a matrix region 121 and a plurality of columnar regions 113 (first columnar structures) and columnar regions 123 (second columnar structures) having different refractive indexes from the matrix regions 121. As shown in FIG. 5, the columnar region 113 exists across the anisotropic light diffusion layers 110 and 120, and the columnar region 123 exists only in the anisotropic light diffusion layer 120.

Here, the aspect ratio (= average major axis / average minor axis) of the average minor axis and the average major axis on the surface of the anisotropic light diffusion layer 110 (or the cross section perpendicular to the alignment direction) of the columnar regions 113 and 123 may be different. Is preferred. More specifically, the anisotropic optical film according to the present invention has the above-described pillar structure and louver structure inside the anisotropic light diffusion layer in a preferred embodiment.
Here, the cross-sectional shape of the cross section perpendicular to the alignment direction of the columnar regions 113 and 123 is not particularly limited. However, when the columnar region 113 has a louver structure, the columnar region 123 may have a pillar structure. Alternatively, when the columnar region 113 has a pillar structure, the columnar region 123 can have a louver structure.

  Thus, the specific configuration of the anisotropic optical film 100 of the present invention includes an anisotropic light diffusion layer 110 having a plurality of columnar regions 113, and a hybrid structure having a plurality of columnar regions 123 and a plurality of columnar regions 113. And an anisotropic light diffusion layer 120. Hereinafter, the anisotropic optical film 100 having the anisotropic light diffusion layer 110 and the anisotropic light diffusion layer 120 will be described in detail. As will be described later, since the aspect ratios of the columnar regions 113 and 123 are not limited, both the columnar region 113 and the columnar region 123 have a pillar structure (or louver) depending on the combination of the aspect ratios of the columnar region 113 and the columnar region 123. Such a form is also within the scope of the present invention.

<< anisotropic light diffusion layer 110 >>
The anisotropic light diffusion layer 110 has a columnar region 113 and has a light diffusibility in which the linear transmittance changes depending on the incident light angle. The anisotropic light diffusing layer 110 is made of a cured product of a composition containing a photopolymerizable compound. As shown in FIGS. 5 and 6A, the matrix region 111 and the matrix region 111 have a plurality of different refractive indexes. It has a columnar region 113. The alignment direction (extending direction) P of the columnar region 113 is formed so as to be parallel to the scattering center axis, and is appropriately determined so that the anisotropic light diffusion layer 110 has desired linear transmittance and diffusibility. ing. It should be noted that the fact that the scattering central axis and the alignment direction of the columnar region are parallel only needs to satisfy the law of refractive index (Snell's law), and does not need to be strictly parallel. Snell's law, when the light to the interface of the medium refractive index _{n 2} from a medium of refractive index _{n 1} is incident, between the incident light angle theta ₁ and refraction angle θ _2, n ₁ sinθ 1 = The relationship of n ₂ sin θ ₂ is established. For example, when n ₁ = 1 (air) and n ₂ = 1.51 (anisotropic optical film), when the incident light angle is 30 °, the alignment direction (refractive angle) of the columnar region is about 19 °. However, even if the incident light angle and the refraction angle are different from each other as long as Snell's law is satisfied, it is included in the parallel concept in this embodiment.

  In addition, as the anisotropic light-diffusion layer 110, the orientation direction of the columnar area | region 113 may not correspond with the film thickness direction (normal direction) of a film. In this case, in the anisotropic light diffusion layer 110, incident light is strongly diffused in an incident light angle range (diffusion region) close to a direction inclined by a predetermined angle from the normal direction (that is, the orientation direction of the columnar region 113). In the incident light angle range (non-diffusion region) beyond that, the diffusion is weakened and the linear transmittance is increased.

<Columnar region 113>
The columnar region 113 according to this embodiment is provided as a plurality of columnar hardened regions in the matrix region 111, and each columnar region 113 is formed so that the alignment direction is parallel to the scattering center axis. Is. Accordingly, the plurality of columnar regions 113 in the same anisotropic light diffusion layer 110 are formed to be parallel to each other.

  Although the refractive index of the matrix area | region 111 should just differ from the refractive index of the columnar area | region 113, how much a refractive index differs is not specifically limited, It is a relative thing. When the refractive index of the matrix region 111 is lower than the refractive index of the columnar region 113, the matrix region 111 becomes a low refractive index region. Conversely, when the refractive index of the matrix region 111 is higher than the refractive index of the columnar region 113, the matrix region 111 becomes a high refractive index region. Here, the refractive index at the interface between the matrix region 111 and the columnar region 113 preferably changes gradually. By changing the angle gradually, the change in diffusibility when the incident light angle is changed becomes extremely steep, and the problem that glare is likely to occur is less likely to occur. By forming the matrix region 111 and the columnar region 113 by phase separation accompanying light irradiation, the refractive index of the interface between the matrix region 111 and the columnar region 113 can be gradually increased.

  In the present invention, it is preferable to have a configuration in which the interface between the columnar region 113 and the matrix region 111 is continuously present in the thickness direction of the single anisotropic light diffusion layer 110 without interruption. By having a configuration in which the interface between the columnar region 113 and the matrix region 111 is connected, light diffusion and condensing easily occur continuously while passing through the anisotropic light diffusion layer 110, and the efficiency of light diffusion and condensing. Goes up. On the other hand, in the cross section of the anisotropic light diffusing layer 110, it is not preferable that the columnar region 113 and the matrix region 111 are mainly mottled because it becomes difficult to obtain the light collecting property.

  The cross-sectional shape perpendicular to the alignment direction of the columnar region 113 has a short diameter SA and a long diameter LA as shown in FIG. 6A. The short diameter SA and the long diameter LA can be confirmed by observing the anisotropic light diffusion layer 110 with an optical microscope (details will be described later). For example, in FIG. 6A, the cross-sectional shape of the columnar region 113 is shown as an ellipse, but the cross-sectional shape of the columnar region 113 is not particularly limited. In this case, the minor axis SA and the major axis LA have the same shape when the cross-sectional shape is circular, for example, and the minor axis SA and the major axis LA have the same length. The upper limit of the distance between the two points included in the major axis LA, and the lower limit of the minor point SA.

<< anisotropic light diffusion layer 120 >>
The anisotropic light diffusing layer 120 has a light diffusibility in which the columnar region 113 and the columnar region 123 coexist, and the linear transmittance changes depending on the incident light angle. Further, as shown in FIG. 6B, the anisotropic light diffusion layer 120 is made of a cured product of a composition containing a photopolymerizable compound, and the matrix region 121 and a plurality of columnar regions 113 having different refractive indexes from the matrix region 121. And 123. The plurality of columnar regions 113 and 123 and the matrix region 121 have an irregular distribution and shape, but the optical characteristics (for example, linear transmittance) obtained by being formed over the entire surface of the anisotropic light diffusion layer 120 are as follows. It will be almost the same. Since the plurality of columnar regions 113 and 123 and the matrix region 121 have an irregular distribution or shape, the anisotropic light diffusion layer 120 according to this embodiment is less likely to cause light interference (rainbow).

<Columnar region 113>
The columnar region 113 according to this embodiment is provided as a plurality of columnar hardened regions in the matrix region 121, and each columnar region 113 is formed so that the alignment direction is parallel to the scattering center axis. Is. Accordingly, the plurality of columnar regions 113 in the same anisotropic light diffusion layer 120 are formed to be parallel to each other. The plurality of columnar regions 113 in the anisotropic light diffusion layer 120 are the same as the plurality of columnar regions 113 in the anisotropic light diffusion layer 110, and detailed description thereof is omitted (as described above, the columnar regions 113 are anisotropic light diffusion layers). A structure that continuously exists across the layer 110 and the anisotropic light diffusion layer 120).

<Columnar region 123>
The columnar region 123 according to this embodiment is provided as a plurality of columnar hardened regions in the matrix region 121, and each columnar region 123 is formed so that the alignment direction is parallel to the scattering center axis. Is. Therefore, the plurality of columnar regions 123 in the same anisotropic light diffusion layer 120 are formed to be parallel to each other.

  Although the refractive index of the matrix area | region 121 should just differ from the refractive index of the columnar area | regions 113 and 123, how much a refractive index differs is not specifically limited, It is a relative thing. When the refractive index of the matrix region 121 is lower than the refractive indexes of the columnar regions 113 and 123, the matrix region 121 becomes a low refractive index region. Conversely, when the refractive index of the matrix region 121 is higher than the refractive indexes of the columnar regions 113 and 123, the matrix region 121 becomes a high refractive index region.

The cross-sectional shape perpendicular to the alignment direction of the columnar region 123 has a minor axis SA and a major axis LA, as shown in FIG. 6B. For example, in FIG. 6B, the cross-sectional shape of the columnar region 123 is shown in a circular shape, but the cross-sectional shape of the columnar region 123 is not limited to a circular shape, and is elliptical, polygonal, indefinite, There is no particular limitation such as a mixture.
In this case, the minor axis SA and the major axis LA have the same shape when the cross-sectional shape is circular, for example, and the minor axis SA and the major axis LA have the same length. The upper limit of the distance between the two points included in the major axis LA, and the lower limit of the minor point SA.

<< Shape of columnar region >>
<Aspect ratio of the columnar region 113 and the columnar region 123>
When either one of the columnar region 113 and the columnar region 123 has a louver structure, the aspect ratio (= average major axis / average minor axis) of the average value (average minor axis) of the minor axis SA and the average value (average major axis) of the major axis LA ) Is preferably 2 or more, more preferably 2 or more and less than 50, still more preferably 2 or more and 10 or less, and particularly preferably 2 or more and 5 or less.

  Further, when either one of the columnar region 113 and the columnar region 123 has a pillar structure, the aspect ratio (= average major axis / average minor axis SA) and average average major axis LA (average major axis). The average minor axis) is preferably less than 2, more preferably less than 1.5, and still more preferably less than 1.2.

  The anisotropic optical film 100 according to this embodiment has various characteristics at a higher level in a well-balanced manner by setting both the average minor axis and the aspect ratio of the average major axis of the columnar region 113 and the columnar region 123 within the above preferable range. An anisotropic optical film can be obtained.

<Average minor axis and average major axis of columnar region 113 and columnar region 123>
The average value (average minor axis) of the minor axis SA of the columnar region 113 and the columnar region 123 is preferably 0.5 μm or more, more preferably 1.0 μm or more, and 1.5 μm or more. Is more preferable. On the other hand, the average value (average minor axis) of the minor axis SA of the columnar region 113 and the columnar region 123 is preferably 5.0 μm or less, more preferably 4.0 μm or less, and 3.0 μm or less. Is more preferable. The lower limit value and upper limit value of the average minor axis of the columnar region 113 and the columnar region 123 can be appropriately combined.

  Furthermore, the average value (average major axis) of the major axis LA of one of the columnar region 113 and the columnar region 123 is preferably 0.5 μm or more, more preferably 1.0 μm or more, and 1.5 μm or more. More preferably it is. On the other hand, the average value (average major axis) of the major axis LA of either one of the columnar region 113 and the columnar region 123 is preferably 100 μm or less, more preferably 50 μm or less, and preferably 30 μm or less. Further preferred. The lower limit value and the upper limit value of the average major axis of either one of the columnar region 113 and the columnar region 123 can be appropriately combined.

  Further, of the columnar region 113 and the columnar region 123, the average value (average major axis) of the other major axis LA in the paragraph 0052 is preferably 0.5 μm or more, more preferably 1.0 μm or more. More preferably, it is 5 μm or more. On the other hand, in the columnar region 113 and the columnar region 123, the average value (average major axis) of the other major axis LA in the paragraph 0052 is preferably 8.0 μm or less, more preferably 5.0 μm or less. More preferably, it is 0 μm or less. Of the columnar region 113 and the columnar region 123, the lower limit value and the upper limit value of the other average major axis in the paragraph 0052 can be appropriately combined.

  The anisotropic optical film 100 according to the present embodiment has an anisotropic property having various properties in a balanced manner at a higher level by setting both the average minor axis and the average major axis of the columnar region 113 and the columnar region 123 within the preferable range. It can be an optical film.

  Note that the average value of the minor axis SA (average minor axis) and the average value of the major axis LA (average major axis) of each of the columnar region 113 and the columnar region 123 in this embodiment are the surface of the anisotropic light diffusion layer 120 (shown in FIG. 5). The lower end surface 129) is observed with a microscope, the short diameter SA and the long diameter LA of 100 arbitrarily selected columnar regions 113 and columnar regions 123 are measured, and the average value thereof may be obtained. Further, as the aspect ratio of the columnar region, a value obtained by dividing the average value (average major axis) of the major axis LA obtained above by the average value (average minor axis) of the minor axis SA is used.

  Note that the anisotropic optical film 100 according to this embodiment includes an anisotropic light diffusion layer 110 having a matrix region 111 and a plurality of columnar regions 113 having a refractive index different from that of the matrix region 111, a matrix region 121, and a matrix region. 121 has at least an anisotropic light diffusion layer 120 having a plurality of columnar regions 113 and columnar regions 123 having different refractive indexes, but another anisotropic light diffusion layer may be continuously formed as a single layer. . More specifically, for example, the anisotropic optical film 100 according to the present embodiment includes an anisotropic light diffusion layer 110 having a matrix region 111 and a plurality of columnar regions 113 having a refractive index different from that of the matrix region 111; An anisotropic light diffusion layer 120 having a region 121 and a plurality of columnar regions 113 and columnar regions 123 having different refractive indexes from the matrix region 121; a matrix region and a plurality of columnar regions 113 having different refractive indexes from the matrix region; Three or more layers such as an anisotropic light diffusion layer having a columnar region 123 and a columnar region different from the columnar region 113 and the columnar region 123 (a columnar region not present in the anisotropic light diffusion layers 110 and 120). The anisotropic light diffusion layer may be continuously formed as a single layer.

<< Area where columnar regions 113 and 123 are formed >>
The columnar region 113 is formed in both the anisotropic light diffusion layers 110 and 120. The total thickness of the anisotropic light diffusion layers 110 and 120 is preferably 10 μm to 200 μm, as will be described later.

  The columnar region 123 is formed in the anisotropic light diffusion layer 120. The columnar region 123 is formed from a position near between the anisotropic light diffusion layer 110 and the anisotropic light diffusion layer 120 toward the lower end surface 129 of the anisotropic light diffusion layer 120. The columnar region 123 is formed from a position exceeding 20% of the total thickness of the anisotropic light diffusion layers 110 and 120 from the upper end surface 119 of the anisotropic light diffusion layer 110 to the lower end surface 129 of the anisotropic light diffusion layer 120. It is preferable (in other words, the anisotropic light diffusion layer 110 is preferably more than 20% of the total thickness). Note that the columnar region 123 is formed from the upper end surface 119 of the anisotropic light diffusion layer 110 to the lower end surface 129 of the anisotropic light diffusion layer 120 from a position that is more than 40% of the total thickness of the anisotropic light diffusion layers 110 and 120. (In other words, the anisotropic light diffusion layer 110 is more preferably more than 40% of the total thickness).

<Thickness of anisotropic light diffusion layer>
As described above, the total thickness of the anisotropic light diffusion layer 110 and the anisotropic light diffusion layer 120 is preferably 10 μm to 200 μm, more preferably 20 μm to less than 100 μm, and more preferably 20 μm to less than 50 μm. More preferably it is. When the thickness exceeds 200 μm, not only the material cost is increased, but also the cost for UV irradiation is increased. And a decrease in contrast tends to occur. In addition, when the thickness is less than 10 μm, it may be difficult to achieve sufficient light diffusibility and light condensing performance. In the present invention, by setting the thickness of the anisotropic light diffusion layer within the specified range, the problem of cost is reduced, the light diffusibility and the light collecting property are excellent, and the thickness of the anisotropic light diffusion layer is increased. Due to the decrease in light diffusibility, image blurring hardly occurs and the contrast can be improved.

<< Properties of Anisotropic Optical Film 100 >>
As described above, the anisotropic optical film 100 has the anisotropic light diffusion layers 110 and 120. More specifically, the anisotropic light diffusion layer 110 has a louver structure (preferably a region having a columnar region with an aspect ratio of 2 or more). The anisotropic light diffusion layer 120 is a hybrid having a pillar structure (preferably a region having a columnar region with an aspect ratio of less than 2) and a louver structure (preferably a region having a columnar region with an aspect ratio of 2 or more). It has a structure. Hereinafter, the properties of the anisotropic optical film 100 will be described.

<Linear transmittance>
Here, if the linear transmittance of light incident on the anisotropic optical film 100 (anisotropic light diffusion layers 110 and 120) at the incident light angle at which the linear transmittance is maximum is defined as “maximum linear transmittance”, it is anisotropic. The optical optical film 100 (anisotropic light diffusing layers 110 and 120) preferably has a maximum linear transmittance of 30% or more, more preferably 50% or more, and further preferably 70% or more.

  Note that the linear transmittance of light incident on the anisotropic light diffusion layers 110 and 120 at an incident light angle that minimizes the linear transmittance can be defined as “minimum linear transmittance”.

  By setting the maximum linear transmittance of the anisotropic optical film 100 within the above range, the anisotropic optical film 100 can have an appropriate anisotropy, so that the application range of the anisotropic optical film 100 can be widened. For example, when the anisotropic optical film 100 is used in a display device, if the anisotropy is too strong, the light diffusion / condensation property in the MD direction is extremely excellent, but the light diffusion / condensation in the TD direction is excellent. There is a problem that the property tends to be insufficient. The anisotropic optical film 100 according to this embodiment has the above-described maximum linear transmittance, so that it maintains excellent light diffusion / condensation in the MD direction, and then diffuses light in the TD direction. It has sufficient light collecting properties.

  Here, the linear transmitted light amount and the linear transmittance can be measured by the method shown in FIG. That is, the linear transmitted light amount and the linear transmittance are measured for each incident light angle so that the rotation axis L shown in FIG. 2 coincides with the CC axis shown in FIGS. 6A and 6B (the normal direction is 0). °). An optical profile is obtained from the obtained data, and the maximum linear transmittance and the minimum linear transmittance can be obtained from the optical profile.

  Further, the maximum linear transmittance and the minimum linear transmittance in the anisotropic optical film 100 (the anisotropic light diffusion layers 110 and 120) can be adjusted by design parameters at the time of manufacture. Examples of the parameters include the composition of the coating film, the film thickness of the coating film, the temperature to the coating film given during structure formation, and the like. The composition of the coating film changes the maximum linear transmittance and the minimum linear transmittance by appropriately selecting and preparing the constituent components. In the design parameter, the maximum linear transmittance and the minimum linear transmittance tend to be lower as the film thickness is thicker, and higher as the film thickness is thinner. The maximum linear transmittance and the minimum linear transmittance tend to be lower as the temperature is higher, and higher as the temperature is lower. Each of the maximum linear transmittance and the minimum linear transmittance can be appropriately adjusted by a combination of these parameters.

<Diffusion width>
By the above method, the maximum linear transmittance and the minimum linear transmittance of the anisotropic optical film 100 are obtained, and the linear transmittance of an intermediate value between the maximum linear transmittance and the minimum linear transmittance is obtained. Two incident light angles with respect to the linear transmittance of the intermediate value are read. In the optical profile, the normal direction is 0 °, and the incident light angle is shown in the minus direction and the plus direction. Therefore, the incident light angle and the incident light angle corresponding to the intersection may have a negative value. If the value of the two intersections has a positive incident light angle value and a negative incident light angle value, the sum of the absolute value of the negative incident light angle value and the positive incident light angle value is the diffusion of the incident light. It becomes the diffusion width, which is the angular range of the region. When the values of the two intersections are both positive, the difference obtained by subtracting the smaller value from the larger value is the diffusion width that is the angle range of the incident light angle. When the values of the two intersections are both negative, the absolute value of each is taken, and the difference obtained by subtracting the smaller value from the larger value is the diffusion width that is the angle range of the incident light angle.

  In the anisotropic optical film 100, the width of the diffusion region (diffusion width), which is the angle range of two incident light angles with respect to the linear transmittance of the intermediate value between the maximum linear transmittance and the minimum linear transmittance, is MD direction. The angle is preferably 20 ° or more and less than 70 °, more preferably 30 ° or more and less than 70 °, and further preferably 40 ° or more and less than 70 °. Further, in the TD direction, it is preferably 5 ° or more and less than 30 °, more preferably 10 ° or more and less than 30 °, and further preferably 20 ° or more and less than 30 °. When it is out of the specified range, that is, when the diffusion width becomes too wide, the light condensing property is weakened. When the diffusion width is too narrow, the display property and visibility are lowered due to the weakening of the diffusivity. Resulting in. That is, according to the present invention, when the diffusion width is within the specified range, it is possible to balance the diffusibility and the light condensing property, and to further enhance the effect of suppressing a sudden change in brightness and glare.

<Scattering central axis>
Next, the scattering center axis P in the anisotropic light diffusion layer will be described with reference to FIG. FIG. 13 is a three-dimensional polar coordinate display for explaining the scattering center axis P in the anisotropic optical film 100 (anisotropic light diffusion layer).

  The anisotropic light diffusing layer has at least one scattering central axis. As described above, the scattering central axis has a light diffusibility when the incident light angle to the anisotropic light diffusing layer is changed. Means a direction coinciding with the incident light angle of light having substantially symmetry with respect to. Note that the incident light angle at this time is approximately the center (the center of the diffusion region) sandwiched between the minimum values in the optical profile obtained by measuring the optical profile of the anisotropic light diffusion layer.

  Further, according to the three-dimensional polar coordinate display as shown in FIG. 13, the scattering central axis is defined as polar angle θ and azimuth when the surfaces of the anisotropic light diffusion layers 110 and 120 are the xy plane and the normal is the z axis. It can be expressed by φ. That is, it can be said that Pxy in FIG. 13 is the length direction of the scattering central axis projected on the surface of the anisotropic light diffusion layer.

  Here, the anisotropic light diffusion layer 110 includes a columnar region 113, and the anisotropic light diffusion layer 120 includes a columnar region 113 and a columnar region 123 (the columnar region 113 includes the anisotropic light diffusion layer 110 and the anisotropic light diffusion layer 120. Exists across the board). Polar angle θ (−90 ° <θ <90 °) formed by the normal line (z axis shown in FIG. 13) of the anisotropic light diffusion layer (anisotropic light diffusion layers 110 and 120) and the columnar region 113 (columnar region 123). Is defined as the scattering center axis angle in this embodiment, the absolute value of the difference between the scattering center axis angle of the columnar region 113 and the scattering center axis angle of the columnar region 123 is preferably 0 ° or more and 30 ° or less. By setting the absolute value of the difference in scattering center axis angle within the above range, the effect of the present invention can be further enhanced. In order to realize this effect more effectively, the absolute value of the difference between the scattering center axis angle of the columnar region 113 and the scattering center axis angle of the columnar region 123 is more preferably 0 ° or more and 20 ° or less, More preferably, the angle is 10 ° or more and 20 ° or less. In addition, the scattering center axis angles of the columnar region 113 and the columnar region 123 are adjusted to a desired angle by changing the direction of the light beam applied to the composition containing the sheet-like photopolymerizable compound when manufacturing them. can do. In addition, the positive / negative of the scattering center axis angle is a predetermined symmetry axis in the plane direction of the anisotropic light diffusion layers 110 and 120 (for example, an axis in the MD direction passing through the center of gravity of the anisotropic light diffusion layers 110 and 120) and the anisotropic light diffusion layer. A case where the scattering center axis is inclined to one side with respect to a plane passing through both normal lines 110 and 120 is defined as +, and a case where the scattering center axis is inclined to the other side is defined as −.

  In addition to the fact that the absolute value of the difference in the scattering center axis angle (polar angle) satisfies the above range, the difference between the azimuth angle of the scattering center axis of the columnar region 113 and the azimuth angle of the scattering center axis of the columnar region 123. The absolute value of is preferably 0 ° or more and 20 ° or less. Thereby, the width of the diffusion region can be further increased without reducing the linear transmittance in the non-diffusion region of the anisotropic optical film 100.

  Here, each of the anisotropic light diffusion layers 110 and 120 may include a plurality of columnar region groups having different inclinations (a set of columnar regions having the same inclination) in a single layer. Thus, when there are a plurality of columnar region groups having different inclinations in a single layer, there are also a plurality of scattering central axes corresponding to the inclination of each group of columnar regions. When there are a plurality of scattering center axes, it is only necessary that at least one of the plurality of scattering center axes satisfies the above-described condition of the scattering center axis angle. For example, when the anisotropic light diffusion layer 110 has two scattering center axes P1 and P2, and the anisotropic light diffusion layer 120 has four scattering center axes P1, P2, P3, and P4, at least one of P1 and P2 The absolute value of the difference between one of the scattering center axis angles and at least one of the scattering center axis angles of P3 and P4 is preferably 0 ° or more and 30 ° or less. The lower limit of the absolute value of the difference in scattering center axis angle is more preferably 5 °. On the other hand, the upper limit of the absolute value of the difference in scattering center axis angle is more preferably 20 °, and further preferably 15 °.

  In addition, the polar angle θ (that is, the scattering center axis angle) of the scattering center axis P of the columnar region 113 and the columnar region 123 is preferably ± 10 to 60 °, and more preferably ± 30 to 45 °. When the scattering center axis angle is greater than −10 ° and less than + 10 °, the contrast and brightness of the display panel including the liquid crystal display device cannot be sufficiently improved. On the other hand, when the scattering center axis angle is greater than + 60 ° or less than −60 °, it is necessary to irradiate the composition containing the photopolymerizable compound provided in the form of a sheet from a deep inclination in the production process. This is not preferable because the absorption efficiency of irradiation light is poor and the manufacturing is disadvantageous.

<Refractive index>
The anisotropic light diffusion layers 110 and 120 are obtained by curing a composition containing a photopolymerizable compound. As the composition, the following combinations can be used.
(1) Those using a single photopolymerizable compound to be described later (2) Those using a plurality of photopolymerizable compounds to be described later (3) Single or a plurality of photopolymerizable compounds and no photopolymerizability Used by mixing with polymer compounds

  In any of the above combinations, it is presumed that a micron-order fine structure with a different refractive index is formed in the anisotropic light diffusion layers 110 and 120 by light irradiation. It is thought that anisotropic light diffusion characteristics are exhibited. Therefore, in the above (1), it is preferable that the refractive index change is large before and after photopolymerization, and in (2) and (3), it is preferable to combine a plurality of materials having different refractive indexes. Here, the refractive index change and the refractive index difference specifically indicate a change or difference of 0.01 or more, preferably 0.05 or more, more preferably 0.10 or more.

<Other forms of anisotropic optical film>
The anisotropic optical film 100 according to this embodiment has an anisotropic light diffusion layer (in this embodiment, a continuous layer including anisotropic light diffusion layers 110 and 120) made of a cured product of a composition containing a photopolymerizable compound. The anisotropic light diffusing layer may be laminated on the translucent substrate. Here, as the translucent substrate, the higher the transparency, the better, and the total light transmittance (JIS K7361-1) is 80% or more, more preferably 85% or more, and most preferably 90% or more. The haze value (JIS K7136) is preferably 3.0 or less, more preferably 1.0 or less, and most preferably 0.5 or less. Specifically, a transparent plastic film, a glass plate, or the like can be used as the translucent substrate. However, a plastic film is preferable because it is thin, light, difficult to break, and has excellent productivity. Specific examples include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), triacetyl cellulose (TAC), polycarbonate (PC), polyethersulfone (PES), cellophane, polyethylene (PE), polypropylene (PP), and polyvinyl. Alcohol (PVA), cycloolefin resin, etc. are mentioned, These can be used alone or in combination and further laminated. The thickness of the translucent substrate is preferably 1 μm to 5 mm, more preferably 10 to 500 μm, still more preferably 50 to 150 μm in consideration of the use and productivity.

  The anisotropic optical film according to the present invention may be an anisotropic optical film in which another layer is provided on one surface on the anisotropic light diffusion layer 110 side or 120 side. Examples of the other layers include a polarizing layer, a light diffusion layer, a low reflection layer, an antifouling layer, an antistatic layer, an ultraviolet / near infrared (NIR) absorption layer, a neon cut layer, and an electromagnetic wave shielding layer. . Other layers may be sequentially stacked. Furthermore, another layer may be laminated on both surfaces of the anisotropic light diffusion layer 110 side and / or the 120 side. The other layer laminated on both surfaces may be a layer having the same function or a layer having another function.

<<< Method for Manufacturing Anisotropic Optical Film According to this Embodiment >>>
As mentioned above, although the structure of the anisotropic optical film 100 which concerns on this form was demonstrated in detail, it continues and the manufacturing method of the anisotropic optical film 100 which has this structure is demonstrated.

  The anisotropic optical film 100 according to this embodiment (an anisotropic light diffusing layer having continuous anisotropic light diffusing layers 110 and 120 in one layer) is produced by irradiating the photocurable composition layer with light such as UV. be able to. Hereinafter, the raw materials of the anisotropic light diffusion layer (anisotropic light diffusion layers 110 and 120) will be described first, and then the manufacturing process will be described.

<< Raw material of anisotropic light diffusion layer >>
About the raw material of an anisotropic light-diffusion layer (anisotropic light-diffusion layers 110 and 120), it demonstrates in order of (1) photopolymerizable compound, (2) photoinitiator, (3) compounding quantity, and other arbitrary components.

<Photopolymerizable compound>
The photopolymerizable compound that is a material for forming the anisotropic light diffusion layers 110 and 120 according to the present embodiment is a photopolymerizable compound selected from a macromonomer, a polymer, an oligomer, and a monomer having a radical polymerizable or cationic polymerizable functional group. It is a material composed of a compound and a photoinitiator and polymerized and cured by irradiation with ultraviolet rays and / or visible rays. Here, even if the material for forming the anisotropic light diffusing layer included in the anisotropic optical film 100 is one kind, a difference in refractive index is generated due to the difference in density. This is because a portion having a high UV irradiation intensity has a fast curing speed, and thus the polymerized / cured material moves around the cured region, resulting in formation of a region having a higher refractive index and a region having a lower refractive index. . In addition, (meth) acrylate means that either acrylate or methacrylate may be sufficient.

  The radically polymerizable compound mainly contains one or more unsaturated double bonds in the molecule, specifically, epoxy acrylate, urethane acrylate, polyester acrylate, polyether acrylate, polybutadiene acrylate, silicone acrylate, etc. Acrylic oligomer called by the name of 2-ethylhexyl acrylate, isoamyl acrylate, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isonorbornyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate 2-acryloyloxyphthalic acid, dicyclopentenyl acrylate, triethylene glycol diacrylate Neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, EO adduct diacrylate of bisphenol A, trimethylolpropane triacrylate, EO-modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylol Examples thereof include acrylate monomers such as propanetetraacrylate and dipentaerythritol hexaacrylate. In addition, these compounds may be used alone or in combination. Similarly, methacrylate can also be used, but acrylate is generally preferable to methacrylate because of its higher photopolymerization rate.

  As the cationically polymerizable compound, a compound having at least one epoxy group, vinyl ether group or oxetane group in the molecule can be used. The compounds having an epoxy group include 2-ethylhexyl diglycol glycidyl ether, glycidyl ether of biphenyl, bisphenol A, hydrogenated bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetrachloro Diglycidyl ethers of bisphenols such as bisphenol A and tetrabromobisphenol A, polyglycidyl ethers of novolac resins such as phenol novolak, cresol novolak, brominated phenol novolak, orthocresol novolak, ethylene glycol, polyethylene glycol, polypropylene glycol, Butanediol, 1,6-hexanediol, neopentyl glycol, trimethyl Diglycidyl ethers of alkylene glycols such as propane adduct of 1,4-cyclohexanedimethanol, bisphenol A, PO adduct of bisphenol A, glycidyl ester of hexahydrophthalic acid, diglycidyl ester of dimer acid, etc. Examples thereof include glycidyl esters.

  Further, as the compound having an epoxy group, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) Cyclohexane-meta-dioxane, di (3,4-epoxycyclohexylmethyl) adipate, di (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl-3 ′, 4 ′ -Epoxy-6'-methylcyclohexanecarboxylate, methylene bis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, di (3,4-epoxycyclohexylmethyl) ether of ethylene glycol, ethylene bis (3,4-epoxy Cyclohexane cal Xylate), lactone-modified 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, tetra (3,4-epoxycyclohexylmethyl) butanetetracarboxylate, di (3,4-epoxycyclohexylmethyl)- Examples thereof include, but are not limited to, alicyclic epoxy compounds such as 4,5-epoxytetrahydrophthalate.

  Examples of the compound having a vinyl ether group include diethylene glycol divinyl ether, triethylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, hydroxybutyl vinyl ether, ethyl vinyl ether, dodecyl vinyl ether, trimethylol propane tri Vinyl ether, propenyl ether propylene carbonate and the like can be mentioned, but are not limited thereto. Vinyl ether compounds are generally cationically polymerizable, but radical polymerization is also possible by combining with acrylates.

  As the compound having an oxetane group, 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 3-ethyl-3- (hydroxymethyl) -oxetane and the like can be used.

The above cationic polymerizable compounds may be used alone or in combination. The photopolymerizable compound is not limited to the above. In order to cause a sufficient difference in refractive index, fluorine atoms (F) may be introduced into the photopolymerizable compound in order to reduce the refractive index, and in order to increase the refractive index, Sulfur atoms (S), bromine atoms (Br), and various metal atoms may be introduced. Furthermore, as disclosed in JP 2005-514487 A, ultrafine particles made of a metal oxide having a high refractive index such as titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), tin oxide (SnO _x ), etc. It is also effective to add functional ultrafine particles having a photopolymerizable functional group such as an acryl group, a methacryl group, and an epoxy group introduced to the surface to the photopolymerizable compound.

(Photopolymerizable compound having a silicone skeleton)
In this embodiment, it is preferable to use a photopolymerizable compound having a silicone skeleton as the photopolymerizable compound. A photopolymerizable compound having a silicone skeleton is oriented and polymerized and cured in accordance with its structure (mainly ether bond), and has a low refractive index region, a high refractive index region, or a low refractive index region and a high refractive index region. Form. By using a photopolymerizable compound having a silicone skeleton, the columnar regions 113 and 123 can be easily inclined, and the light condensing property in the front direction is improved. The low refractive index region corresponds to one of the columnar regions 113 and 123 or the matrix regions 111 and 121, and the other corresponds to the high refractive index region.

  In the low refractive index region, it is preferable that the silicone resin that is a cured product of the photopolymerizable compound having a silicone skeleton relatively increases. As a result, the scattering central axis can be more easily inclined, and thus the light condensing property in the front direction is improved. Since a silicone resin contains a larger amount of silica (Si) than a compound having no silicone skeleton, relative use of the silicone resin can be achieved by using an EDS (energy dispersive X-ray spectrometer) with this silica as an index. The correct amount.

  The photopolymerizable compound having a silicone skeleton is a monomer, oligomer, prepolymer or macromonomer having a radically polymerizable or cationically polymerizable functional group. Examples of the radical polymerizable functional group include an acryloyl group, a methacryloyl group, and an allyl group. Examples of the cationic polymerizable functional group include an epoxy group and an oxetane group. There are no particular restrictions on the type and number of these functional groups, but it is preferable to have a polyfunctional acryloyl group or methacryloyl group because the crosslink density increases and the difference in refractive index tends to occur as the number of functional groups increases. . Moreover, although the compound which has a silicone frame | skeleton may be inadequate in compatibility with another compound from the structure, in such a case, it can urethanize and can improve compatibility. In this embodiment, silicone, urethane, (meth) acrylate having an acryloyl group or a methacryloyl group at the terminal is preferably used.

  The weight average molecular weight (Mw) of the photopolymerizable compound having a silicone skeleton is preferably in the range of 500 to 50,000. More preferably, it is the range of 2,000-20,000. When the weight average molecular weight is in the above range, a sufficient photocuring reaction occurs, and the silicone resin present in each anisotropic light diffusion layer of the anisotropic optical film 100 is easily oriented. With the orientation of the silicone resin, the scattering central axis is easily inclined.

Examples of the silicone skeleton include those represented by the following general formula (1). In the general formula (1), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ are each independently a methyl group, an alkyl group, a fluoroalkyl group, a phenyl group, an epoxy group, an amino group, a carboxyl group. And functional groups such as a polyether group, an acryloyl group, and a methacryloyl group. Moreover, in general formula (1), it is preferable that n is an integer of 1-500.

(Compound without silicone skeleton)
When an anisotropic light diffusion layer is formed by blending a photopolymerizable compound having a silicone skeleton with a compound that does not have a silicone skeleton, the low refractive index region and the high refractive index region are likely to be separated and formed anisotropically. The degree of is strong and preferable. As the compound having no silicone skeleton, a thermoplastic resin or a thermosetting resin can be used in addition to the photopolymerizable compound, and these can be used in combination. As the photopolymerizable compound, a polymer, oligomer, or monomer having a radical polymerizable or cationic polymerizable functional group can be used (however, it does not have a silicone skeleton). Examples of the thermoplastic resin include polyester, polyether, polyurethane, polyamide, polystyrene, polycarbonate, polyacetal, polyvinyl acetate, acrylic resin, and a copolymer or modified product thereof. In the case of using a thermoplastic resin, it is dissolved using a solvent in which the thermoplastic resin dissolves, and after application and drying, the photopolymerizable compound having a silicone skeleton is cured with ultraviolet rays to form an anisotropic light diffusion layer. Examples of the thermosetting resin include epoxy resins, phenol resins, melamine resins, urea resins, unsaturated polyesters, copolymers thereof, and modified products. In the case of using a thermosetting resin, the photopolymerizable compound having a silicone skeleton is cured with ultraviolet rays and then appropriately heated to cure the thermosetting resin and form the anisotropic light diffusion layer. The most preferable compound that does not have a silicone skeleton is a photopolymerizable compound, which easily separates a low refractive index region and a high refractive index region, and does not require a solvent and a drying process when a thermoplastic resin is used. It is excellent in productivity, such as being no thermal curing process like a thermosetting resin.

<Photoinitiator>
Photoinitiators that can polymerize radically polymerizable compounds include benzophenone, benzyl, Michler's ketone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2- Diethoxyacetophenone, benzyldimethyl ketal, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2 -Methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1 -One, bis (cyclo Ntadienyl) -bis (2,6-difluoro-3- (pyr-1-yl) titanium, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2,4,6 -Trimethyl benzoyl diphenyl phosphine oxide etc. Moreover, these compounds may be used individually or may be used in mixture of two or more.

The photoinitiator of the cationic polymerizable compound is a compound capable of generating an acid by light irradiation and polymerizing the above cationic polymerizable compound with the generated acid. Generally, an onium salt, a metallocene is used. Complexes are preferably used. As the onium salt, a diazonium salt, a sulfonium salt, an iodonium salt, a phosphonium salt, a selenium salt, or the like is used, and these counter ions include anions such as BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ^{− and the} like. Used. Specific examples include 4-chlorobenzenediazonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, (4-phenylthiophenyl) diphenylsulfonium hexafluoroantimonate, (4-phenylthiophenyl) diphenyl. Sulfonium hexafluorophosphate, bis [4- (diphenylsulfonio) phenyl] sulfide-bis-hexafluoroantimonate, bis [4- (diphenylsulfonio) phenyl] sulfide-bis-hexafluorophosphate, (4-methoxyphenyl) Diphenylsulfonium hexafluoroantimonate, (4-methoxyphenyl) phenyliodonium hexafluoroantimonate Bis (4-t-butylphenyl) iodonium hexafluorophosphate, benzyltriphenylphosphonium hexafluoroantimonate, triphenyl selenium hexafluorophosphate, (η5-isopropylbenzene) (η5-cyclopentadienyl) iron (II) hexa Although fluorophosphate etc. are mentioned, it is not limited to these. In addition, these compounds may be used alone or in combination.

<Blend amount and other optional ingredients>
In this embodiment, the photoinitiator is 0.01 to 10 parts by weight, preferably 0.1 to 7 parts by weight, more preferably about 0.1 to 5 parts by weight with respect to 100 parts by weight of the photopolymerizable compound. Blended. This is because when less than 0.01 parts by weight, the photo-curing property is lowered, and when blending more than 10 parts by weight, only the surface is cured and the internal curability is lowered, coloring, columnar structure This is because it inhibits the formation of. These photoinitiators are usually used by directly dissolving powder in a photopolymerizable compound, but if the solubility is poor, a photoinitiator dissolved beforehand in a very small amount of solvent at a high concentration is used. It can also be used. Such a solvent is more preferably photopolymerizable, and specific examples thereof include propylene carbonate and γ-butyrolactone. It is also possible to add various known dyes and sensitizers in order to improve the photopolymerizability. Furthermore, the thermosetting initiator which can harden a photopolymerizable compound by heating can also be used together with a photoinitiator. In this case, by heating after photocuring, it can be expected to further accelerate the polymerization and curing of the photopolymerizable compound to complete it.

  In this embodiment, the anisotropic light diffusing layers 110 and 120 can be formed by curing the above photopolymerizable compound alone or by curing a composition obtained by mixing a plurality thereof. The anisotropic light diffusion layers 110 and 120 of this embodiment can also be formed by curing a mixture of a photopolymerizable compound and a polymer resin that does not have photocurability. Examples of polymer resins that can be used here include acrylic resins, styrene resins, styrene-acrylic copolymers, polyurethane resins, polyester resins, epoxy resins, cellulose resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, Examples include polyvinyl butyral resin. These polymer resins and photopolymerizable compounds need to have sufficient compatibility before photocuring, but various organic solvents, plasticizers, etc. are used to ensure this compatibility. It is also possible. In addition, when using an acrylate as a photopolymerizable compound, it is preferable from a compatible point to select as a polymer resin from an acrylic resin.

  The ratio of the photopolymerizable compound having a silicone skeleton and the compound not having a silicone skeleton is preferably in the range of 15:85 to 85:15 by mass ratio. More preferably, it is the range of 30: 70-70: 30. By setting it in this range, the phase separation between the low refractive index region and the high refractive index region can easily proceed, and the columnar region can easily be inclined. If the ratio of the photopolymerizable compound having a silicone skeleton is less than the lower limit value or exceeds the upper limit value, the phase separation is difficult to proceed, and the columnar region is not easily inclined. When silicone / urethane / (meth) acrylate is used as a photopolymerizable compound having a silicone skeleton, compatibility with a compound having no silicone skeleton is improved. Accordingly, the columnar region can be inclined even if the mixing ratio of the materials is widened.

(solvent)
As a solvent for preparing a composition containing a photopolymerizable compound, for example, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, toluene, xylene and the like can be used.

<<< Aspect Example 1 of Anisotropic Optical Film >>>
An embodiment of the anisotropic optical film will be described with reference to FIG.

<< Anisotropic Diffusion Layer 210 >>
As shown in FIG. 7, the anisotropic light diffusion layer 210 has a columnar region 213 having a louver structure, and has a light diffusibility in which the linear transmittance changes depending on the incident light angle.

<Columnar region 213>
The columnar region 213 according to this embodiment is provided as a plurality of columnar hardened regions in the matrix region 211, and each columnar region 213 is formed so that the alignment direction is parallel to the scattering center axis. Is. Accordingly, the plurality of columnar regions 213 in the same anisotropic light diffusion layer 210 are formed to be parallel to each other.

  The refractive index of the matrix region 211 is different from the refractive index of the columnar region 213. The degree to which the refractive index differs is not particularly limited and is relative. When the refractive index of the matrix region 211 is lower than the refractive index of the columnar region 213, the matrix region 211 becomes a low refractive index region. On the contrary, when the refractive index of the matrix region 211 is higher than the refractive index of the columnar region 213, the matrix region 211 becomes a high refractive index region. Here, it is preferable that the refractive index at the interface between the matrix region 211 and the columnar region 213 changes gradually. By changing the angle gradually, the change in diffusibility when the incident light angle is changed becomes extremely steep, and the problem that glare is likely to occur is less likely to occur. By forming the matrix region 211 and the columnar region 213 by phase separation accompanying light irradiation, the refractive index of the interface between the matrix region 211 and the columnar region 213 can be gradually increased.

  In this embodiment, the structure is such that the interface between the columnar region 213 and the matrix region 211 is continuously present in the thickness direction of the single anisotropic light diffusion layer 210 without interruption. By having a configuration in which the interface between the columnar region 213 and the matrix region 211 is connected, light diffusion and light collection are likely to occur continuously while passing through the anisotropic light diffusion layer 210, and light diffusion and light collection efficiency. Can be raised.

  The cross-sectional shape perpendicular to the alignment direction of the columnar region 213 has a minor axis SA and a major axis LA as shown in FIG. 8A, and the aspect ratio of the average minor axis SA and the average major axis LA is 2 or more. It has a structure.

<< anisotropic light diffusion layer 220 >>
The anisotropic light diffusion layer 220 has a light diffusivity in which a columnar region 213 having a louver structure and a columnar region 223 having a pillar structure coexist, and the linear transmittance varies depending on the incident light angle. Further, as shown in FIG. 8B, the anisotropic light diffusion layer 220 is made of a cured product of a composition containing a photopolymerizable compound, and the matrix region 221 and a plurality of columnar regions 213 having different refractive indexes from the matrix region 221. And 223. The plurality of columnar regions 213 and 223 and the matrix region 221 have irregular distribution and shape, but the optical characteristics (for example, linear transmittance, etc.) obtained by being formed over the entire surface of the anisotropic light diffusion layer 220 are as follows. It will be almost the same. Since the plurality of columnar regions 213 and 223 and the matrix region 221 have an irregular distribution and shape, the anisotropic light diffusion layer 220 according to this embodiment is less likely to generate light interference (rainbow).

<Columnar region 213>
The columnar region 213 according to this aspect is provided as a plurality of columnar cured regions in the matrix region 221, and each columnar region 213 is formed so that the orientation direction is parallel to the scattering center axis. Is. Therefore, the plurality of columnar regions 213 in the same anisotropic light diffusion layer 220 are formed to be parallel to each other. The plurality of columnar regions 213 in the anisotropic light diffusion layer 220 are the same as the plurality of columnar regions 213 in the anisotropic light diffusion layer 210.

<Columnar region 223>
The columnar region 223 according to this embodiment is provided as a plurality of columnar hardened regions in the matrix region 221, and each columnar region 223 is formed so that the alignment direction is parallel to the scattering center axis. Yes. Therefore, the plurality of columnar regions 223 in the same anisotropic light diffusion layer 220 are formed to be parallel to each other.

  The refractive index of the matrix region 221 is different from the refractive indexes of the columnar regions 213 and 223. The degree to which the refractive index differs is not particularly limited and is relative. When the refractive index of the matrix region 221 is lower than the refractive indexes of the columnar regions 213 and 223, the matrix region 221 is a low refractive index region. Conversely, when the refractive index of the matrix region 221 is higher than the refractive indexes of the columnar regions 213 and 223, the matrix region 221 becomes a high refractive index region.

  The cross-sectional shape perpendicular to the alignment direction of the columnar region 223 having a pillar structure has a minor axis SA and a major axis LA, as shown in FIG. 8B, and the aspect ratio of the average minor axis SA and the average major axis LA is 2. It has a pillar structure that is less than

<< Shape of columnar region >>
<Aspect ratio of the columnar region 213 and the columnar region 223>
The columnar region 213 has a louver structure, and the aspect ratio (= average major axis / average minor axis) of the average value (average minor axis) of the minor axis SA and the average value (average major axis) of the major axis LA is 2 or more.

  Further, the columnar region 223 has a pillar structure, and the aspect ratio (= average major axis / average minor axis) of the average value (average minor axis) of the minor axis SA and the average value (average major axis) of the average major axis LA is less than 2. .

  The anisotropic optical film 200 according to the present embodiment has various characteristics at a higher level in a well-balanced manner by setting both the average minor axis and the average major axis aspect ratio of the columnar region 213 and the columnar region 223 within the preferable range. An anisotropic optical film can be obtained.

<Average minor axis and average major axis of columnar region 213 and columnar region 223>
The columnar region 213 has a louver structure, the average value (average minor axis) of the minor axis SA of the columnar region 213 is 0.5 μm to 5.0 μm, and the average value (average major axis) of the major axis LA is 1 μm to 100 μm. .

  The columnar region 223 has a pillar structure, the average value (average short axis) of the minor axis SA of the columnar region 223 is 0.5 μm to 5.0 μm, and the average value (average major axis) of the major axis LA is 0.5 μm to 5 μm. 0.0 μm.

  The anisotropic optical film 200 according to the present embodiment has an anisotropy having various properties in a balanced manner at a higher level by setting both the average minor axis and the average major axis of the columnar region 213 and the columnar region 223 within the above-described preferable range. It can be an optical film.

<<< Aspect Example 2 of Anisotropic Optical Film >>>
Another example of the embodiment of the anisotropic optical film will be described with reference to FIG.

<< Anisotropic Diffusion Layer 310 >>
As shown in FIG. 9, the anisotropic light diffusion layer 310 has a pillar-shaped region 313 having a pillar structure, and has a light diffusibility in which the linear transmittance changes depending on the entrance light angle.

<Columnar region 313>
The columnar region 313 according to this embodiment is provided as a plurality of columnar hardened regions in the matrix region 311, and each columnar region 313 is formed so that the alignment direction is parallel to the scattering center axis. Is. Accordingly, the plurality of columnar regions 313 in the same anisotropic light diffusion layer 310 are formed to be parallel to each other.

  The refractive index of the matrix region 311 is different from the refractive index of the columnar region 313. The degree to which the refractive index differs is not particularly limited and is relative. When the refractive index of the matrix region 311 is lower than the refractive index of the columnar region 313, the matrix region 311 is a low refractive index region. Conversely, when the refractive index of the matrix region 311 is higher than the refractive index of the columnar region 313, the matrix region 311 becomes a high refractive index region. Here, the refractive index at the interface between the matrix region 311 and the columnar region 313 is preferably one that gradually increases. By changing the angle gradually, the change in diffusibility when the incident light angle is changed becomes extremely steep, and the problem that glare is likely to occur is less likely to occur. By forming the matrix region 311 and the columnar region 313 by phase separation accompanying light irradiation, the refractive index of the interface between the matrix region 311 and the columnar region 313 can be gradually increased.

  In this embodiment, the interface between the columnar region 313 and the matrix region 311 is continuously present without interruption over the thickness direction of the single anisotropic light diffusion layer 310. By having a configuration in which the interface between the columnar region 313 and the matrix region 311 is connected, light diffusion and light collection are likely to occur continuously while passing through the anisotropic light diffusion layer 310, and light diffusion and light collection efficiency. Can be raised.

  The cross-sectional shape perpendicular to the alignment direction of the columnar region 313 has a pillar structure in which the aspect ratio of the average minor axis SA and the average major axis LA is less than 2, as shown in FIG. 10A.

<< Anisotropic Light Diffusion Layer 320 >>
The anisotropic light diffusion layer 320 has a columnar region 313 having a pillar structure and a columnar region 323 having a louver structure, and has a light diffusibility in which the linear transmittance varies depending on the incident light angle. Also, as shown in FIG. 10B, the anisotropic light diffusion layer 320 is made of a cured product of a composition containing a photopolymerizable compound, and the matrix region 321 and the plurality of columnar regions 313 having different refractive indexes from the matrix region 321. And 323. The plurality of columnar regions 313 and 323 and the matrix region 321 have irregular distribution and shape, but the optical characteristics (for example, linear transmittance) obtained by being formed over the entire surface of the anisotropic light diffusion layer 320 are as follows. It will be almost the same. Since the plurality of columnar regions 313 and 323 and the matrix region 321 have an irregular distribution or shape, the anisotropic light diffusion layer 320 according to this embodiment is less likely to generate light interference (rainbow).

<Columnar region 313>
The columnar region 313 according to this aspect is provided as a plurality of columnar cured regions in the matrix region 321, and each columnar region 313 is formed so that the alignment direction is parallel to the scattering center axis. Is. Accordingly, the plurality of columnar regions 313 in the same anisotropic light diffusion layer 320 are formed to be parallel to each other. The plurality of columnar regions 313 in the anisotropic light diffusion layer 320 are the same as the plurality of columnar regions 313 in the anisotropic light diffusion layer 310, and detailed description thereof will be omitted (as described above, the columnar regions 313 are anisotropic light diffusion layers). A structure that continuously exists across the layer 310 and the anisotropic light diffusion layer 320).

<Columnar region 323>
The columnar region 323 according to this embodiment is provided as a plurality of columnar hardened regions in the matrix region 321, and each columnar region 323 is formed so that the alignment direction is parallel to the scattering center axis. Yes. Therefore, the plurality of columnar regions 323 in the same anisotropic light diffusion layer 320 are formed to be parallel to each other.

  The refractive index of the matrix region 321 is different from the refractive indexes of the columnar regions 313 and 323. The degree to which the refractive index differs is not particularly limited and is relative. When the refractive index of the matrix region 321 is lower than the refractive indexes of the columnar regions 313 and 323, the matrix region 321 becomes a low refractive index region. Conversely, when the refractive index of the matrix region 321 is higher than the refractive indexes of the columnar regions 313 and 323, the matrix region 321 becomes a high refractive index region.

  As shown in FIG. 10B, the cross-sectional shape perpendicular to the orientation direction of the columnar region 323 having a louver structure is an elliptical shape, and an average value of the minor axis SA (average minor axis) and an average value of the major axis LA (average major axis). The aspect ratio (= average major axis / average minor axis) is 2 or more.

<< Shape of columnar region >>
<Aspect ratio of columnar region 313 and columnar region 323>
The columnar region 313 has a pillar structure, and an aspect ratio (= average major axis / average minor axis) of an average value (average minor axis) of the minor axis SA and an average value (average major axis) of the major axis LA is less than 2.

  The columnar region 323 has a louver structure, and the aspect ratio (= average major axis / average minor axis) of the average value (average minor axis) of the minor axis SA and the average value (average major axis) of the major axis LA is 2 or more. .

  The anisotropic optical film 300 according to this aspect has various characteristics at a higher level in a well-balanced manner by setting both the average minor axis and the average major axis aspect ratio of the columnar region 313 and the columnar region 323 within the above-described preferable range. An anisotropic optical film can be obtained.

<Average minor axis and average major axis of columnar region 313 and columnar region 323>
The columnar region 313 has a pillar structure, the average value (average minor axis) of the minor axis SA of the columnar region 313 is 0.5 μm to 5.0 μm, and the average value (average major axis) of the major axis LA is 0.5 μm to 5 μm. 0.0 μm.

  The columnar region 323 has a louver structure, the average value (average minor axis) of the minor axis SA of the columnar region 323 is 0.5 μm to 5.0 μm, and the average value (average major axis) of the major axis LA is 1 μm to 100 μm. .

  The anisotropic optical film 300 according to the present embodiment has an anisotropy having various properties in a balanced manner at a higher level by setting both the average minor axis and the average major axis of the columnar region 313 and the columnar region 323 within the above preferable range. It can be an optical film.

<< Manufacturing Process of Anisotropic Optical Film >>
Next, based on FIG.11 and FIG.12, the process (manufacturing method) of the anisotropic optical films 200 and 300 of this form is demonstrated. 11 and 12 show an outline of the manufacturing process of the anisotropic optical films 200 and 300 of the present embodiment and the columnar regions 213 and 223 grown according to the manufacturing process of the anisotropic optical films 200 and 300, and the columnar regions 313 and 323. The outline of is shown.

  The outline of the manufacturing process of the anisotropic optical films 200 and 300 is as follows. First, a composition containing the above-mentioned photopolymerizable compound (hereinafter sometimes referred to as “photocurable composition”) is applied on a suitable substrate (substrate) such as a transparent PET film, or a sheet form. And a photocurable composition layer is provided by film formation. The photocurable composition layer is dried as necessary to volatilize the solvent, and then the photocurable composition layer is irradiated with light, whereby the anisotropic light diffusion layers 210 and 220, and the anisotropic light diffusion layer are irradiated. An anisotropic light diffusion layer having the layers 310 and 320 as one layer can be manufactured. Below, what applied the photocurable composition on the base | substrate or provided in the sheet form is called the coating films 250 and 350. FIG.

<Example of forming process of anisotropic optical film 200>
The following steps will be described in detail as a step of forming the anisotropic optical film 200 according to this embodiment.
(Step 1) A coating step of applying a composition for forming an anisotropic light diffusion layer on a substrate and providing a coating film 250 (Step 2) A mask film lamination step of laminating a mask film on the coating film 250 (Any)
(Step 3) After the first structure forming step (anisotropic light diffusing layer 210 forming step) and the first structure forming step of curing on the coating film 250 by irradiation with unidirectional diffused light, continuously, Second structure forming step (an anisotropic light diffusing layer 220 forming step) in which the coating film 250 is cured by irradiation with parallel rays.

<Process 1: Coating process>
In step 1, as a method of providing the composition containing the photopolymerizable compound in a sheet form on the substrate, a normal coating method or printing method is applied. Specifically, air doctor coating, bar coating, blade coating, knife coating, reverse coating, transfer roll coating, gravure roll coating, kiss coating, cast coating, spray coating, slot orifice coating, calendar coating, dam coating, dip coating Coating such as die coating, intaglio printing such as gravure printing, printing such as stencil printing such as screen printing, and the like can be used. When the composition has a low viscosity, a weir having a certain height can be provided around the substrate, and the composition can be cast in the area surrounded by the weir.

<Process 2: Mask film lamination process (optional)>
In step 2, in order to prevent oxygen inhibition of the photocurable composition layer and efficiently form the columnar region 213 that is a feature of the anisotropic light diffusion layer 210 according to this embodiment, the light of the photocurable composition layer It is preferable to laminate a mask film (hereinafter simply referred to as a mask or the like) that closely contacts the irradiation side and locally changes the light irradiation intensity. The material of the mask is not particularly limited. For example, a normal transparent plastic film or the like may be used. However, a light-absorbing filler such as carbon is dispersed in a matrix, and a part of incident light is carbon. Although it is absorbed, the opening may have a configuration that allows light to be sufficiently transmitted. Examples of such a matrix include transparent plastics such as PET, TAC, PVAc, PVA, acrylic and polyethylene, inorganic materials such as glass and quartz, and patterning and ultraviolet rays for controlling the amount of ultraviolet rays transmitted to a sheet containing these matrices. It may also contain a pigment that absorbs. When such a mask is not used, it is also possible to prevent oxygen inhibition of the photocurable composition layer by performing light irradiation in a nitrogen atmosphere. Further, simply laminating a normal transparent film on the photocurable composition layer is effective in preventing oxygen inhibition and promoting the formation of the columnar region 213. Thus, light irradiation through a mask or a transparent film is effective for producing the anisotropic light diffusion layer 210 according to this embodiment.

<Step 3: anisotropic light diffusion layer forming step>
Next, an apparatus used in the anisotropic light diffusion layer forming step will be described based on FIG. 11, and a specific formation process of the anisotropic light diffusion layer will be described.

〔apparatus〕
First, as shown in FIG. 11, the anisotropic optical film 200 is manufactured mainly by a light source (not shown), a directional diffusion element 240, a light shielding plate 230, and a moving stage (not shown). And are used.

  The moving stage is for moving the coating film 250 at a predetermined speed. The moving stage is driven by a stepping motor, a linear motor (not shown) or the like, and the moving speed, moving direction, and the like are controlled by a motor driver. More specifically, in FIG. 11, the coating film 250 on the moving stage is continuously movable from the position shown in the state (a) to the position shown in the state (e).

  The light source irradiates the emitted light onto the coating film 250 and causes the phase separation to cure while forming the columnar regions 213 and 223 to form the anisotropic light diffusion layers 210 and 120. It is. Details of the process of forming the columnar regions 213 and 223 will be described later.

  As the light source, a short arc ultraviolet light source is usually used. Specifically, a high pressure mercury lamp, a low pressure mercury lamp, a metahalide lamp, a xenon lamp, or the like can be used.

  In particular, in the process of forming the columnar region 223 described later, it is necessary to irradiate a light beam parallel to the desired scattering center axis Q on the photocurable composition layer. In order to obtain such parallel light D, a point light source is disposed, and an optical lens such as a reflection mirror or a Fresnel lens for irradiating the parallel light D between the point light source and the photocurable composition layer is provided. What is necessary is just to arrange. Through such an optical lens, the light emitted from the light source is converted into the parallel light D, and the parallel light D can be irradiated onto the coating film 250 (photocurable composition layer).

The light beam applied to the composition containing the photopolymerizable compound needs to have a wavelength capable of curing the photopolymerizable compound, and usually a light having a wavelength centered at 365 nm of a mercury lamp is used. . When fabricating the anisotropic light-diffusing layer 210 with the wavelength band, it is preferred that as the illumination intensity is in the range of 0.01 to 100 mW / cm ^2, more preferably from 0.1~20mW / cm ² It is. When the illuminance is less than 0.01 mW / cm ² , it takes a long time to cure, so the production efficiency may deteriorate, and when it exceeds 100 mW / cm ² , the photopolymerizable compound cures too quickly, resulting in structure formation. This is because the desired anisotropic diffusion characteristics may not be achieved.

  The directional diffusion element 240 is for imparting directivity to the parallel light D and converting it into the diffused light E. The columnar region 213 is formed by irradiating the coating film 250 with the diffused light E.

  The directivity diffusing element 240 may be any element that imparts directivity to the incident parallel light D. In order to obtain the diffused light E having directivity in this way, for example, the needle-shaped filler having a high aspect ratio is contained in the directional diffusion element 240, and the long axis direction of the needle-shaped filler is in the Y direction. A method of aligning so as to extend can be employed. Various methods can be used for the directional diffusion element 240 in addition to the method using a needle-like filler. What is necessary is just to arrange | position so that the parallel light D may obtain the diffused light E through the directional diffusion element 240. FIG. A specific example of such a directional diffusion element 240 is a lenticular lens.

  The light shielding plate 230 blocks light emitted from the light source so that the composition containing the photopolymerizable compound is not irradiated with light. The material, size, thickness, and the like of the light shielding plate 230 may be determined as appropriate according to the wavelength and intensity of light emitted from the light source.

  Here, as shown in FIG. 11, the directional diffusion element 240 is disposed so as to protrude from the shielding plate 230 in a direction along the moving direction of the coating film 250. By doing in this way, the area AR1 where all the light emitted from the light source is blocked by the shielding plate 230, the area AR2 where the diffused light E is irradiated, and the area AR3 where the parallel light D is irradiated Regions can be formed.

  Hereinafter, a specific process for forming the anisotropic light diffusion layer in each of the regions divided into the regions AR1 to AR3 will be described.

(Process in area AR1)
In the process of the AR1 region, the entire coating film 250 is still covered with the light shielding plate 230, and the light emitted from the light source is not irradiated onto the coating film 250. At this stage, all of the coating film 250 is located in the area AR1. Accordingly, as shown in the state (a) of FIG. 11, the columnar regions 213 and 223 are not formed, and the entire coating film 250 is in an uncured state.

(Process of area AR2: process of forming anisotropic light diffusion layer 210)
When the coating film 250 moves a certain distance by driving the moving stage, the coating film 250 moves from the area AR1 to the area AR2.

  In the process of the area AR2, the coating film 250 is gradually exposed from the light shielding plate 230 by driving the moving stage. Here, the coating film 250 is located in two regions, the region AR1 and the region AR2. As the coating film 250 is exposed from the light shielding plate 230, it moves from the area AR1 to the area AR2. In the area AR2, the coating film 250 is irradiated with the diffused light E.

  By irradiating the diffused light E onto the coating film 250, phase separation starts from the upper surface of the coating film 250. By irradiation with the diffused light E, the columnar region 213 starts to be formed from the upper surface of the coating film 250 and grows gradually. Along with the formation of the columnar region 213, a matrix region 211 is also formed.

  More specifically, as shown in the state (b) of FIG. 11, phase separation starts from the upper surface of the coating film 250, and columnar regions 213 and matrix regions 211 start to be formed from the upper surface toward the lower surface by phase separation. . At this time, as shown in the state (c) of FIG. 11, the columnar region 213 and the matrix region 211 do not reach the lower surface, and are formed up to an intermediate position between the upper surface and the lower surface of the coating film 250. It is in a state. Note that the intermediate position is not limited to the center or center position between the upper surface and the lower surface, and indicates an arbitrary position in a region sandwiched between the upper surface and the lower surface.

  As shown in the states (b) and (c) of FIG. 11, the columnar region 213 and the matrix region 211 are formed from the upper surface of the coating film 250 to an intermediate position. The coating film 250 is a structure in which the region from the upper surface to the intermediate position is cured to form a louver structure, and the region from the intermediate position to the lower surface remains uncured and no structure is formed. It will be in an unformed state.

  Here, in this step, the size (aspect ratio, minor axis SA, major axis LA, etc.) of the formed columnar region 213 can be appropriately determined by adjusting the irradiation intensity and spread of the diffused light E.

  The spread of the diffused light E mainly depends on the distance between the directional diffusion element 240 and the coating film 250, the type of the directional diffusion element 240, and the like. As the distance decreases, the size of the columnar region decreases, and as the distance increases, the size of the columnar region increases. Therefore, the size of the columnar region can be adjusted by adjusting the distance.

  In this step, the aspect ratio of the diffused light E is preferably 2 or more. The aspect ratio of the columnar region 213 is formed substantially corresponding to the aspect ratio. Since the diffusion range may become narrower as the aspect ratio becomes smaller, the aspect ratio is set to 2 or more in this embodiment. The aspect ratio is more preferably 2 or more and less than 50, still more preferably 2 or more and 10 or less, and particularly preferably 2 or more and 5 or less. By setting the aspect ratio in such a range, the light diffusibility and light condensing property are excellent.

(Process of area AR3: anisotropic light diffusion layer 220 forming process)
When the coating film 250 is further moved by driving the moving stage, the process of the area AR3 is performed.

  In the process of the area AR3, the coating film 250 is gradually exposed also from the directional diffusion element 240. Here, the coating film 250 is located in at least two regions, the region AR2 and the region AR3. In this process, a part of the coating film 250 may still be located in the area AR1.

  As the coating film 250 is exposed from the directional diffusion element 240, the coating film 250 moves from the area AR2 to the area AR3. In the area AR3, the parallel light D is irradiated onto the coating film 250.

  As shown in the state (d) and the state (e) of FIG. 11, the parallel light D is irradiated onto the coating film 250, whereby further phase separation starts from an intermediate position of the coating film 250 and the columnar region 223. Begins to form and grows gradually. As described above, the growth of the columnar region 213 has started in the step of the region AR2, and the columnar region 213 continues to grow in the step of the region AR3.

  In the process of the area AR3, the matrix area 221 is also formed with the formation of the columnar areas 213 and 223, and the columnar areas 213 and 223 and the matrix area 221 reach the lower surface. Thus, in the region from the intermediate position to the lower surface, a hybrid structure in which two types of structures of a louver structure formed by the columnar region 213 and a pillar structure formed by the columnar region 223 coexist is formed. By forming the hybrid structure, the region from the intermediate position to the lower surface is also cured.

  Thus, the coating film 250 undergoes the process of the area AR2 and the process of the area AR3, so that only the louver structure is formed from the upper surface to the intermediate position, and the louver structure and the pillar structure are formed from the intermediate position to the lower surface. A hybrid structure consisting of

In the present embodiment, a method using a moving stage is employed to continuously form the anisotropic light diffusion layers 210 and 220, but the present invention is not limited to this, and FIGS. The upper layer of the coating film is cured by a method such as c) (up to the process of the area AR2) as one process and the processes up to (d) to (e) of FIG. Also by forming the anisotropic light diffusion layer 210 and then forming the anisotropic light diffusion layer 220 by changing the light irradiation conditions in a state where an uncured layer exists as the lower layer of the coating film, etc. The anisotropic optical film 200 according to this embodiment can be formed.

  In the anisotropic light diffusion layer forming step, the total light irradiation time is not particularly limited, but is 10 to 180 seconds, more preferably 10 to 120 seconds.

The anisotropic light diffusing layers 210 and 220 of this embodiment are obtained by forming a specific internal structure in the photocurable composition layer by irradiating light with low illuminance for a relatively long time as described above. is there. For this reason, unreacted monomer components may remain by such light irradiation alone, resulting in stickiness, which may cause problems in handling properties and durability. In such a case, the residual monomer can be polymerized by additional irradiation with light having a high illuminance of 1000 mW / cm ² or more. The light irradiation at this time is performed from the lower surface side (for example, the opposite side of the side on which the mask is laminated) which is the opposite side of the irradiation performed first for forming the anisotropic light diffusion layer of the coating film 250. Also good.

<Example of forming process of anisotropic optical film 300>
The following steps will be described in detail as a step of forming the anisotropic optical film 300 according to this embodiment.
(Step 1) A coating step of applying a composition for forming an anisotropic light diffusion layer on a substrate and providing a coating film 350 (Step 2) A mask film lamination step of laminating a mask film on the coating film 350 (Any)
(Step 3) After the first structure forming step (anisotropic light diffusing layer 310 forming step) and the first structure forming step of curing on the coating film 350 by irradiation with parallel rays, the coating is continuously performed. A second structure forming step (an anisotropic light diffusing layer 320 forming step) in which curing is performed on the film 350 by irradiation with one-way diffusing light

<Process 1: Coating process>
In step 1, as a method of providing the composition containing the photopolymerizable compound in a sheet form on the substrate, a normal coating method or printing method is applied. Specifically, air doctor coating, bar coating, blade coating, knife coating, reverse coating, transfer roll coating, gravure roll coating, kiss coating, cast coating, spray coating, slot orifice coating, calendar coating, dam coating, dip coating Coating such as die coating, intaglio printing such as gravure printing, printing such as stencil printing such as screen printing, and the like can be used. When the composition has a low viscosity, a weir having a certain height can be provided around the substrate, and the composition can be cast in the area surrounded by the weir.

<Process 2: Mask film lamination process (optional)>
In step 2, in order to prevent oxygen inhibition of the photocurable composition layer and efficiently form the columnar region 313 that is a feature of the anisotropic light diffusion layer 310 according to this embodiment, the light of the photocurable composition layer It is preferable to laminate a mask film (hereinafter simply referred to as a mask or the like) that closely contacts the irradiation side and locally changes the light irradiation intensity. The material of the mask is not particularly limited. For example, a normal transparent plastic film or the like may be used. However, a light-absorbing filler such as carbon is dispersed in a matrix, and a part of incident light is carbon. Although it is absorbed, the opening may have a configuration that allows light to be sufficiently transmitted. Examples of such a matrix include transparent plastics such as PET, TAC, PVAc, PVA, acrylic and polyethylene, inorganic materials such as glass and quartz, and patterning and ultraviolet rays for controlling the amount of ultraviolet rays transmitted to a sheet containing these matrices. It may also contain a pigment that absorbs. When such a mask is not used, it is also possible to prevent oxygen inhibition of the photocurable composition layer by performing light irradiation in a nitrogen atmosphere. Also, simply laminating a normal transparent film on the photocurable composition layer is effective in preventing oxygen inhibition and promoting the formation of the columnar region 313. Thus, light irradiation through a mask or a transparent film is effective for producing the anisotropic light diffusion layer 310 according to this embodiment.

<Step 3: anisotropic light diffusion layer forming step>
Next, an apparatus used in the anisotropic light diffusion layer forming step will be described based on FIG. 12, and a specific formation process of the anisotropic light diffusion layer will be described.

〔apparatus〕
First, as shown in FIG. 12, the anisotropic optical film 300 is manufactured mainly by a light source (not shown), a directional diffusion element 340, a light shielding plate 330, and a moving stage (not shown). And are used.

  The moving stage is for moving the coating film 350 at a predetermined speed. The moving stage is driven by a stepping motor, a linear motor (not shown) or the like, and the moving speed, moving direction, and the like are controlled by a motor driver. More specifically, in FIG. 12, the coating film 350 on the moving stage can be continuously moved from the position shown in the state (a) to the position shown in the state (e).

  The light source irradiates the emitted light onto the coating film 350 and causes the phase separation to cure while forming the columnar regions 313 and 323 to form the anisotropic light diffusion layers 310 and 320. It is. Details of the process of forming the columnar regions 313 and 323 will be described later.

  As the light source, a short arc ultraviolet light source is usually used. Specifically, a high pressure mercury lamp, a low pressure mercury lamp, a metahalide lamp, a xenon lamp, or the like can be used.

  In particular, in the process of forming a columnar region 313 described later, it is necessary to irradiate a light beam parallel to a desired scattering center axis Q on the photocurable composition layer. In order to obtain such parallel light D, a point light source is disposed, and an optical lens such as a reflection mirror or a Fresnel lens for irradiating the parallel light D between the point light source and the photocurable composition layer is provided. What is necessary is just to arrange. Through such an optical lens, the light emitted from the light source is converted into parallel light D, and the parallel light D can be irradiated onto the coating film 350 (photocurable composition layer).

The light beam applied to the composition containing the photopolymerizable compound needs to have a wavelength capable of curing the photopolymerizable compound, and usually a light having a wavelength centered at 365 nm of a mercury lamp is used. . When fabricating the anisotropic light-diffusing layer 310 with the wavelength band, it is preferred that as the illumination intensity is in the range of 0.01 to 100 mW / cm ^2, more preferably from 0.1~20mW / cm ² It is. When the illuminance is less than 0.01 mW / cm ² , it takes a long time to cure, so the production efficiency may deteriorate, and when it exceeds 100 mW / cm ² , the photopolymerizable compound cures too quickly, resulting in structure formation. This is because the desired anisotropic diffusion characteristics may not be achieved.

  The directivity diffusing element 340 imparts directivity to the parallel light D and converts it into diffused light E. The columnar region 323 is formed by irradiating the coating film 350 with the diffused light E.

  The directivity diffusing element 340 may be any element that imparts directivity to the incident parallel light D. In order to obtain the diffused light E having directivity in this way, for example, the needle-shaped filler having a high aspect ratio is contained in the directivity diffusing element 340, and the long axis direction of the needle-shaped filler is set in the Y direction. A method of aligning so as to extend can be employed. Various methods can be used for the directional diffusion element 340 in addition to the method using a needle-like filler. What is necessary is just to arrange | position so that the parallel light D may obtain the diffused light E through the directional diffusion element 340. A specific example of such a directional diffusion element 340 is a lenticular lens.

  The light blocking plate 330 is for blocking light emitted from the light source so that the composition containing the photopolymerizable compound is not irradiated with light. The material, size, thickness, and the like of the light shielding plate 330 may be determined as appropriate according to the wavelength and intensity of light emitted from the light source.

  Here, as shown in FIG. 12, the directional diffusion element 340 is arranged so as to cover the AR 6 in a direction along the moving direction of the coating film 350. By doing in this way, the area AR4 where all the light emitted from the light source by the shielding plate 330 is blocked, the area AR5 irradiated with the parallel light D, and the area AR6 irradiated with the diffused light E Regions can be formed.

  Hereinafter, a specific process for forming the anisotropic light diffusion layer in each of the regions divided into the regions AR4 to AR6 will be described.

(Process of area AR4)
In the process of the AR4 region, the entire coating film 350 is still covered with the light shielding plate 330, and the light emitted from the light source is not irradiated onto the coating film 350. At this stage, all of the coating film 350 is located in the area AR4. Accordingly, as shown in the state (a) of FIG. 12, the columnar regions 313 and 323 are not formed, and the entire coating film 350 is in an uncured state.

(Process of area AR5: process of forming anisotropic light diffusion layer 310)
When the coating film 350 moves a certain distance by driving the moving stage, the coating film 350 moves from the area AR4 to the area AR5.

  In the process of the area AR5, the coating film 350 is gradually exposed from the light shielding plate 330 by driving the moving stage. Here, the coating film 350 is located in two areas, an area AR4 and an area AR5. As the coating film 350 is exposed from the light shielding plate 330, the coating film 350 moves from the area AR4 to the area AR5. In the area AR5, the parallel light D is applied to the coating film 350.

  By irradiating the parallel light D onto the coating film 350, phase separation starts from the upper surface of the coating film 350. By the irradiation of the parallel light D, the columnar region 313 starts to be formed from the upper surface of the coating film 350 and grows gradually. Along with the formation of the columnar region 313, a matrix region 311 is also formed.

  More specifically, as shown in the state (b) of FIG. 12, phase separation starts from the upper surface of the coating film 350, and columnar regions 313 and matrix regions 311 start to be formed from the upper surface toward the lower surface by phase separation. . At this time, as shown in the state (c) of FIG. 12, the columnar region 313 and the matrix region 311 do not reach the lower surface, and are formed up to an intermediate position between the upper surface and the lower surface of the coating film 350. It is in a state. Note that the intermediate position is not limited to the center or center position between the upper surface and the lower surface, and indicates an arbitrary position in a region sandwiched between the upper surface and the lower surface.

  As shown in the states (b) and (c) of FIG. 12, the columnar region 313 and the matrix region 311 are formed from the upper surface of the coating film 350 to an intermediate position. The coating film 350 has a structure in which the region from the upper surface to the intermediate position is cured to form a pillar structure, and the region from the intermediate position to the lower surface remains uncured and no structure is formed. It will be in an unformed state.

(Process of area AR6: anisotropic light diffusion layer 320 formation process)
When the coating film 350 is further moved by driving the moving stage, the process of the area AR6 is performed.

  In the process of the area AR6, the coating film 350 is gradually covered with the directional diffusion element 340. Here, the coating film 350 is located in at least two regions, the region AR5 and the region AR6. In this step, a part of the coating film 350 may still be located in the area AR4.

  As the coating film 350 is gradually covered by the directional diffusion element 340, the coating film 350 moves from the area AR5 to the area AR6. In the area AR6, the diffused light E is irradiated onto the coating film 350.

  As shown in the state (d) and the state (e) of FIG. 12, the diffused light E is irradiated onto the coating film 350, whereby further phase separation starts from an intermediate position of the coating film 350. Begins to form and grows gradually. As described above, the growth of the columnar region 313 has started in the step of the region AR5, and the columnar region 313 continues to grow in the step of the region AR6.

  In the process of the area AR6, the matrix area 321 is also formed along with the formation of the columnar areas 313 and 323, and the columnar areas 313 and 323 and the matrix area 321 reach the lower surface. Thus, in the region from the intermediate position to the lower surface, a hybrid structure in which two types of structures of a pillar structure formed by the columnar region 313 and a louver structure formed by the columnar region 323 coexist is formed. By forming the hybrid structure, the region from the intermediate position to the lower surface is also cured.

  Here, in this step, the size (aspect ratio, minor axis SA, major axis LA, etc.) of the columnar region 323 to be formed can be appropriately determined by adjusting the irradiation intensity and spread of the diffused light E.

  The spread of the diffused light E mainly depends on the distance between the directional diffusion element 340 and the coating film 350, the type of the directional diffusion element 340, and the like. As the distance decreases, the size of the columnar region decreases, and as the distance increases, the size of the columnar region increases. Therefore, the size of the columnar region can be adjusted by adjusting the distance.

  In this step, the aspect ratio of the diffused light E is preferably 2 or more. The aspect ratio of the columnar region 323 is formed substantially corresponding to the aspect ratio. Since the diffusion range may become narrower as the aspect ratio becomes smaller, the aspect ratio is set to 2 or more in this embodiment. The aspect ratio is more preferably 2 or more and less than 50, still more preferably 2 or more and 10 or less, and particularly preferably 2 or more and 5 or less. By setting the aspect ratio in such a range, the light diffusibility and light condensing property are excellent.

  Thus, the coating film 350 undergoes the process of the area AR5 and the process of the area AR6, so that only the pillar structure is formed from the upper surface to the intermediate position, and the louver structure and the pillar structure are formed from the intermediate position to the lower surface. A hybrid structure consisting of

  In the present embodiment, a method using a moving stage is employed to continuously form the anisotropic light diffusion layers 310 and 320, but the present invention is not limited to this, and FIGS. c) (up to the process of the area AR5) as one process, and the upper layer of the coating film is cured by a method such as a process from FIG. 12 (d) to (e) (after the process of the area AR6) as a separate process. Also by forming the anisotropic light diffusion layer 310 and then forming the anisotropic light diffusion layer 320 by changing the light irradiation conditions in the state where the uncured layer exists as the lower layer of the coating film, etc. The anisotropic optical film 300 according to this embodiment can be formed.

  In the anisotropic light diffusion layer forming step, the total light irradiation time is not particularly limited, but is 10 to 180 seconds, more preferably 10 to 120 seconds.

The anisotropic light diffusing layers 310 and 320 of this embodiment are obtained by forming a specific internal structure in the photocurable composition layer by irradiating light with low illuminance for a relatively long time as described above. is there. For this reason, unreacted monomer components may remain by such light irradiation alone, resulting in stickiness, which may cause problems in handling properties and durability. In such a case, the residual monomer can be polymerized by additional irradiation with light having a high illuminance of 1000 mW / cm ² or more. The light irradiation at this time is performed from the lower surface side (for example, the opposite side of the side on which the mask is laminated) which is the opposite side of the irradiation performed first for forming the anisotropic light diffusion layer of the coating film 350. Also good.

<<< Use of anisotropic optical film according to the present invention >>>
The anisotropic optical film according to the present invention can be suitably used as a diffusion film for a display device. Examples of the display device that can suitably use the anisotropic optical film include a liquid crystal display device (LCD), a plasma display panel (PDP), an organic EL display, a field emission display (FED), a rear projector, and a cathode tube display device. (CRT), surface electric field display (SED), electronic paper, and the like. Especially preferably, it is used for LCD.

  For example, when the anisotropic optical film according to the present embodiment is used for an LCD, the anisotropic optical film may be disposed on the outgoing light side of the LCD. Specifically, in an LCD in which a nematic liquid crystal is sandwiched between a pair of transparent glass substrates on which transparent electrodes are formed, and a pair of polarizing plates are provided on both sides of the glass substrate, on the polarizing plate or glass An anisotropic optical film according to this embodiment can be disposed between the substrate and the polarizing plate. In addition, generally well-known things can be used as said transparent glass substrate, a nematic liquid crystal, a polarizing plate, etc.

  Next, although an example and a comparative example explain the present invention still more concretely, the present invention is not limited at all by these examples.

[Manufacture of anisotropic optical film]
According to the following method, the anisotropic optical film of the present invention and the anisotropic optical film of the comparative example were produced.

Example 1
A partition having a height of 0.045 mm was formed with a curable resin using a dispenser on the entire periphery of the edge of a PET film having a thickness of 100 μm (trade name: A4300, manufactured by Toyobo Co., Ltd.). This was filled with the following photocurable resin composition and covered with a PET film.
Silicone urethane acrylate (refractive index: 1.460, weight average molecular weight: 5,890) 20 parts by weight (trade name: 00-225 / TM18, manufactured by RAHN)
・ Neopentyl glycol diacrylate (refractive index: 1.450) 30 parts by weight (manufactured by Daicel Cytec, trade name Ebecryl 145)
Bisphenol A EO adduct diacrylate (refractive index: 1.536) 15 parts by weight (manufactured by Daicel Cytec, trade name: Ebecyl 150)
・ Phenoxyethyl acrylate (refractive index: 1.518) 40 parts by weight (manufactured by Kyoeisha Chemical Co., Ltd., trade name: light acrylate PO-A)
・ 2,2-dimethoxy-1,2-diphenylethane-1-one 4 parts by weight (manufactured by BASF, trade name: Irgacure 651)

The liquid film with both surfaces sandwiched between PET films is heated to transmit parallel UV light emitted from an epi-illumination irradiation unit of a UV spot light source (trade name: L2859-01, manufactured by Hamamatsu Photonics) from above. Ultraviolet rays converted into linear rays through a directional diffusing element having an aspect ratio of 3 and a minor axis of 2 μm are irradiated vertically for 20 seconds with an irradiation intensity of 5 mW / cm ² , and have different plate-like structures. An isotropic light diffusion layer was formed on the upper layer of the liquid film.

Further, a parallel light beam emitted from the epi-illumination unit of the UV spot light source is continuously irradiated from the upper part perpendicular to the normal direction of the coating surface with an irradiation intensity of 5 mW / cm ² for 20 seconds. An anisotropic light diffusion layer having a large number of plate-like structures was formed in the lower layer of the liquid film to obtain an anisotropic optical film.

  Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structures of the first columnar structure and the second columnar structure after peeling the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Example 2)
Directional diffusing element in which light converted into a linear ray through a directional diffusing element is irradiated for 10 seconds, parallel light is irradiated for 30 seconds, and the aspect ratio of transmitted UV light is 3 and the minor axis is 3 μm An anisotropic optical film of Example 2 was obtained in the same manner as in Example 1 except that Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structures of the first columnar structure and the second columnar structure after peeling the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Example 3)
Light that has been converted to linear rays through a directional diffuser is irradiated for 30 seconds, parallel rays are irradiated for 10 seconds, and the directivity that the aspect ratio of transmitted UV rays is 3 and the minor axis is 1.3 μm An anisotropic optical film of Example 3 was obtained in the same manner as Example 1 except that the diffusing element was changed. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structures of the first columnar structure and the second columnar structure after peeling the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

Example 4
A partition having a height of 0.045 mm was formed with a curable resin using a dispenser on the entire periphery of the edge of a PET film having a thickness of 100 μm (trade name: A4300, manufactured by Toyobo Co., Ltd.). This was filled with the same photocurable resin composition as in Example 1 and covered with a PET film.

The liquid film having both surfaces sandwiched between PET films is heated, and parallel light emitted from the epi-illumination irradiation unit of the UV spot light source from above is perpendicular to the normal direction of the coating surface, and the irradiation intensity is 5 mW / cm ^2. For 10 seconds, an anisotropic light diffusion layer having a large number of columnar structures was formed in the upper layer of the liquid film.

Furthermore, parallel UV light emitted from an epi-illumination irradiation unit of a UV spot light source (manufactured by Hamamatsu Photonics Co., Ltd., product name: L2859-01) is continuously transmitted from the top to the transmitted UV light with an aspect ratio of 3 and a minor axis of 3 μm. An anisotropic light diffusing layer having a large number of columnar structures and plate-like structures is irradiated by vertically irradiating ultraviolet rays converted into linear rays through a directional diffusing element to be irradiated at an irradiation intensity of 5 mW / cm ² for 30 seconds. To form an anisotropic optical film.

  Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structures of the first columnar structure and the second columnar structure after peeling the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film. Moreover, the cross-sectional photograph of MD direction and TD direction of the anisotropic optical film which concerns on this example is shown in FIG.

(Example 5)
Directional diffusing element in which parallel light is irradiated for 30 seconds, light converted to linear light through a directional diffusing element is irradiated for 10 seconds, and the aspect ratio of transmitted UV light is 3 and the minor axis is 1.3 μm A new anisotropic optical film of Example 5 was obtained in the same manner as in Example 4 except that the change was changed to. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structures of the first columnar structure and the second columnar structure after peeling the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Example 6)
An anisotropic optical film of Example 6 was obtained in the same manner as in Example 1 except that the directional diffusion element was changed to a directional diffusion element having an aspect ratio of transmitted UV light of 8 and a minor axis of 2 μm. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structures of the first columnar structure and the second columnar structure after peeling the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Example 7)
An anisotropic optical film of Example 7 was obtained in the same manner as in Example 1 except that the directional diffusion element was changed to a directional diffusion element having an aspect ratio of transmitted UV light of 45 and a minor axis of 2 μm. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structures of the first columnar structure and the second columnar structure after peeling the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Example 8)
Change to a directional diffuser with 20 seconds irradiation of parallel light, 20 seconds of light converted to linear light through a directional diffuser, and a short diameter of 2 μm with a transmitted UV light aspect ratio of 8 Except that, an anisotropic optical film of Example 8 was obtained in the same manner as Example 4. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structures of the first columnar structure and the second columnar structure after peeling the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

Example 9
An anisotropic optical film of Example 9 was obtained in the same manner as in Example 1 except that the ultraviolet irradiation intensity was ² mW / cm ² . Table 1 shows the results of measuring the anisotropic light diffusion layer and the structures of the first columnar structure and the second columnar structure after peeling off the PET film. Furthermore, Table 2 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Example 10)
An anisotropic optical film of Example 7 was obtained in the same manner as in Example 1 except that parallel light was irradiated at an angle of 10 ° from the normal direction of the coating film surface. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structures of the first columnar structure and the second columnar structure after peeling the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film. Moreover, the cross-sectional photograph of MD direction and TD direction of the anisotropic optical film which concerns on this example is shown in FIG.

(Example 11)
Except that the irradiation intensity of linear rays and parallel rays by ultraviolet rays was 3.5 mW / cm ² and that the parallel rays were irradiated at an angle of 25 ° from the normal direction of the coating surface, the same as in Example 1, An anisotropic optical film of Example 8 was obtained. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structures of the first columnar structure and the second columnar structure after peeling the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

Example 12
Same as Example 4 except that parallel rays were irradiated at an angle of 10 ° with respect to the normal direction of the coating surface, and the directional diffuser was changed to a directional diffusing element with a transmitted UV ray aspect ratio of 3 and a minor axis of 2 μm. Thus, a new anisotropic optical film of Example 9 was obtained. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structures of the first columnar structure and the second columnar structure after peeling the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Comparative Example 1)
The anisotropy of Comparative Example 1 is the same as that of Example 1, except that ultraviolet rays converted into linear rays through the directional diffusion element of Example 1 are irradiated for 40 seconds and parallel rays are changed to irradiation for 0 seconds. An optical film was obtained. That is, in this comparative example, an anisotropic optical film having only the first columnar structure was obtained. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structure of the columnar structure after peeling off the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Comparative Example 2)
The anisotropy of Comparative Example 2 is the same as that of Example 1 except that ultraviolet rays converted into linear rays through the directional diffusion element of Example 1 are irradiated for 0 second and parallel rays are irradiated for 40 seconds. An optical film was obtained. That is, in this comparative example, an anisotropic optical film having only the second columnar structure was obtained. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structure of the columnar structure after peeling off the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Comparative Example 3)
Changed to a directional diffuser with a transmitted UV ray aspect ratio of 45 and a minor axis of 2 μm, changed to a linear ray through the directional diffuser for 40 seconds, and changed to a parallel ray for 0 seconds. Except for this, an anisotropic optical film of Comparative Example 3 was obtained in the same manner as Example 1. That is, in this comparative example, an anisotropic optical film having only the first columnar structure was obtained. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structure of the columnar structure after peeling off the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Comparative Example 4)
The partition wall of Example 1 was set to 0.025 mm, and only the ultraviolet rays converted into linear rays through the directional diffusion element were irradiated for 20 seconds perpendicularly from the normal direction of the coating surface, and the first layer anisotropic light diffusion A layer was formed. After obtaining the first anisotropic light diffusing layer, the PET film of the cover is peeled off, and then a 0.020 mm barrier rib is further formed on the barrier rib formed in the first layer to form a different first layer. A similar photocurable resin composition was filled on the isotropic light diffusion layer and covered with a PET film. Thereafter, parallel rays were irradiated for 20 seconds perpendicularly from the normal direction of the coating surface to obtain a second anisotropic light diffusing layer, whereby an anisotropic optical film of Comparative Example 4 was obtained. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structure of the columnar structure after peeling off the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Comparative Example 5)
An anisotropic optical film of Comparative Example 4 was obtained in the same manner except that the order of linear light irradiation and parallel light irradiation of Comparative Example 4 was changed. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structure of the columnar structure after peeling off the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Comparative Example 6)
A partition wall having a height of 0.200 mm was formed from a curable resin in the same manner as in Example 1, and the same photocurable resin composition as in Example 1 was filled therein.
In the same manner as in Example 1, the liquid film is heated so that the parallel UV light emitted from the epi-illumination unit of the UV spot light source is directed from the top so that the transmitted UV light has an aspect ratio of 45 and a minor axis of 2 μm. An anisotropic light diffusing layer having a large number of plate-like structures was formed in the lower layer of the liquid film by vertically irradiating ultraviolet rays converted into linear rays through a diffusing element at an irradiation intensity of 5 mW / cm ² for 20 seconds.
Further, the liquid film is covered with a PET film, and a parallel light beam emitted from an epi-illumination unit of a UV spot light source is irradiated from the top perpendicularly from the normal direction of the coating surface with an irradiation intensity of 5 mW / cm ² for 20 seconds. Then, an anisotropic light diffusion layer having a large number of columnar structures and plate-like structures was formed on the upper layer of the liquid film to obtain an anisotropic optical film of Comparative Example 6. Tables 1 and 2 show the results of measuring the anisotropic light diffusion layer and the structure of the columnar structure after peeling off the PET film. Furthermore, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.
This film had an unstructured layer (thickness 0.095 mm) inside between the louver structure and the pillar structure.

<<< Evaluation method >>>
The anisotropic optical films of Examples and Comparative Examples produced as described above were evaluated as follows.

(Measurement of weight average molecular weight of silicone, urethane, acrylate)
The weight average molecular weight (Mw) of the silicone, urethane, and acrylate used as the photopolymerizable compound was measured under the following conditions using the GPC method as the molecular weight in terms of polystyrene.
Degasser: DG-980-51 (manufactured by JASCO Corporation)
Pump: PU-980-51 (manufactured by JASCO Corporation)
Autosampler: AS-950 (manufactured by JASCO Corporation)
Constant temperature bath: C-965 (manufactured by JASCO Corporation)
Column: Shodex KF-806L x 2 (made by Showa Denko KK)
Detector: RI (SHIMAMURA YDR-880)
Temperature: 40 ° C
Eluent: THF
Injection volume: 150 μl
Flow rate: 1.0 ml / min
Sample concentration: 0.2%

<< Thickness of anisotropic optical film (anisotropic light diffusion layer) >>
The thickness of each anisotropic light diffusion layer of the anisotropic optical films of Examples and Comparative Examples was measured by observing and measuring a cross section of the anisotropic optical film formed using a microtome.

<< Surface observation of anisotropic optical film >>
The surfaces of the anisotropic optical films of Examples and Comparative Examples (opposite to the irradiation light at the time of ultraviolet irradiation) were observed with an optical microscope, and the major axis LA and minor axis SA of arbitrary 100 first columnar structures and the arbitrary The major axis LA and minor axis SA of the 100 second columnar structures were measured, and the average value of each was calculated (see Table 1). Furthermore, the aspect ratio (average major axis / average minor axis) was calculated based on the calculated average major axis and average minor axis.

<< Linear transmittance >>
An anisotropic optical film of Examples and Comparative Examples using a variable angle photometer goniophotometer (manufactured by Genesia) capable of arbitrarily changing the light projection angle of the light source and the light receiving angle of the detector as shown in FIG. Evaluation of the optical properties was performed. The detector was fixed at a position to receive the straight light from the light source, and the anisotropic optical films obtained in Examples and Comparative Examples were set in the sample holder therebetween. As shown in FIG. 2, the sample was rotated as the rotation axis (L), and the amount of linear transmitted light corresponding to each incident light angle was measured. By this evaluation method, it is possible to evaluate in which angle range the incident light is diffused. This rotation axis (L) is the same axis as the CC axis in the sample structure shown in FIG. The linear transmitted light amount was measured by measuring the wavelength in the visible light region using a visibility filter. Based on the optical profile obtained as a result of the above measurement, the maximum value (maximum linear transmittance) and the minimum value (minimum linear transmittance) of the linear transmittance were obtained.

<< MD direction diffusion and TD direction diffusion >>
Using an apparatus as shown in FIG. 2, the anisotropic optical films of the examples and comparative examples are irradiated with straight light from a fixed light source, and the sample is moved (rotated) in the MD direction and the TD direction while transmitting light. The transmittance was measured by making the detector receive light. An optical profile was created based on the transmittance measurement for each of the case where the sample was moved in the MD direction and the case where the sample was moved in the TD direction. Then, from each optical profile when moved in the MD direction and the TD direction, a range of incident light angles which is an intermediate value between the maximum linear transmittance and the minimum linear transmittance is obtained, and these ranges are respectively determined as MD direction diffusion and TD. The width of direction diffusion (°) was used.

<< Rapid change in brightness >>
In the measurement of the linear transmittance described above, as shown in FIG. 16, an angle A (°) that takes the maximum linear transmittance F _A (%) and an angle B (°) that takes the minimum linear transmittance F _B (%) If the linear transmittance suddenly changes during this period, the brightness will also change drastically, so if the slope of the linear transmittance is found and the slope is steep, there will be a sharp change in brightness. If is moderate, it was judged that there was no sudden change in luminance. Specifically, the slope α of the linear transmittance is (F _A −F _B ) / | A−B |, and if this slope α is α ≧ 1.7, there is a sudden change in luminance. If 1.5 ≦ α <1.7, the change is somewhat abrupt but acceptable, and if α <1.5, it is determined that the luminance change is gradual and there is no sense of incongruity. In addition, as shown in FIG. 17, in the following two types of maximum linear transmittance (F _A1 and F _A2 ) and minimum linear transmittance (F _B1 and F _B2 ), values of the following (a) and (b) Those having a larger value were designated as F _A and A, and F _B and B.
(A) (F _A1 -F _B1 ) / | A ₁ -B ₁ |
(B) (F _A2 -F _B2 ) / | A ₂ -B ₂ |
That is, the larger value of the above (a) and (b) was used as the inclination α from the maximum linear transmittance to the minimum linear transmittance in the optical profile.

<< Glitter >>
The light reflection layer was provided in the lower layer of the anisotropic optical film of an Example and a comparative example, light was entered from the upper direction, and the glare of the reflected light was confirmed visually.

<< Productivity >>
Productivity is a process for producing an anisotropic optical film, and the production can be performed continuously (one pass) without interrupting the production, and the productivity is high. In this case, it was determined that the productivity was low.

<<< Evaluation criteria >>>
The evaluation criteria for evaluation in Table 2 are as follows.
"Maximum linear transmittance"
◎ 70% or more ○ 50% or more and less than 70% △ 30% or more and less than 50% × less than 30% “MD diffusion width”
◎ 40 ° or more ○ 30 ° or more and less than 40 ° △ 20 ° or more and less than 30 ° x less than 20 ° “TD diffusion width”
◎ 20 ° or more ○ 10 ° or more but less than 20 ° △ 5 ° or more but less than 10 ° x less than 5 ° “Rapid change in brightness”
◎ Luminance change is gradual, no sense of incongruity △ Slight change, but allowable range x Rapid change in brightness `` Glitter ''
◎ No glare △ There is some glare, but the allowable range × Glare is clear “Productivity”
◎ Manufacturable by 1-pass coating / UV irradiation, high productivity × 2 pass or more coating / UV irradiation required, low productivity

<<< Evaluation Result >>>
The examples had a high level of characteristics in a well-balanced manner in all evaluation items. On the other hand, the comparative example had a very bad result that at least one of the items was x.

  More specifically, as shown in Table 3, the anisotropic optical films of the examples have a high maximum linear transmittance, a wide diffusion width in the MD direction and the TD direction, and sudden changes in brightness and glare. It was also excellent in productivity and had a high level of balance in all evaluation items. In particular, in Example 1, Example 8, and Example 10, since there was no evaluation of (triangle | delta), it can be said that it is an especially excellent anisotropic optical film. On the other hand, some of the anisotropic optical films of the comparative examples had evaluations superior to the examples in specific items, but the maximum linear transmittance, TD direction diffusion, rapid change in luminance, glare, At least one of the items of productivity had a very bad result of ×, and as in the examples, none of the evaluation items had a high level of characteristics in a well-balanced manner. .

  Therefore, the anisotropic optical film of the example can achieve both a high linear transmittance in the non-diffusing region and a wide diffusion region in the MD direction and the TD direction. When used as a film, it is possible to suppress sudden changes in luminance and glare while having excellent display characteristics (such as luminance and contrast). That is, according to the anisotropic optical film of this example, it is possible to compensate for the respective disadvantages of the pillar structure and the louver structure, and the transmittance of the non-diffusing region is improved and the MD direction is improved as compared with the pillar structure. As compared with the louver structure, the diffusion angle range in the TD direction can be expanded and a sudden change in brightness and glare can be eliminated. In addition, since the defects of both structures can be compensated without stacking layers, the productivity is also excellent.

  The preferred embodiment of the present invention has been described above with reference to the drawings, but the present invention is not limited to the above-described embodiment. That is, it is understood that other forms or various modifications that can be conceived by those skilled in the art within the scope of the invention described in the claims belong to the technical scope of the present invention.

100, 200, 300 Anisotropic optical film 110, 210, 310 Anisotropic light diffusion layer (having a single columnar region) 111, 211, 311 Matrix region 113, 213, 313 Columnar region 119 Upper end surface 120, 220, 320 Anisotropic light diffusing layer (having a hybrid structure) 121, 221 and 321 Matrix region 123, 223, 323 Columnar region 129 Lower end surface 240, 340 Directional diffusion element 330 Light shielding plate 250, 350 Coating film SA Short diameter LA Long diameter

Claims (9)

An anisotropic optical film having at least an anisotropic light diffusing layer whose linear transmittance varies depending on the incident light angle,
The anisotropic optical film has a matrix region, a plurality of first columnar structures, and a plurality of second columnar structures,
The first columnar structure is configured by being oriented from one surface of the anisotropic light diffusion layer to the other surface,
The second columnar structure is configured to be oriented from the one surface of the anisotropic light diffusion layer to the other surface from a position exceeding 20% of the thickness of the anisotropic light diffusion layer. An anisotropic optical film characterized. In one of the first columnar structure and the second columnar structure, the aspect ratio between the average minor axis and the average major axis is 2 or more,
2. The anisotropic optical film according to claim 1, wherein an aspect ratio between an average minor axis and an average major axis in the other of the first columnar structure and the second columnar structure is less than 2. 3. . The average minor axis and the average major axis in one of the first columnar structure and the second columnar structure are 0.5 μm to 5.0 μm and 1 μm to 100 μm, respectively.
The average minor axis and average major axis in the other of the first columnar structure and the second columnar structure are 0.5 μm to 5.0 μm and 0.5 μm to 8.0 μm, respectively. Item 3. The anisotropic optical film according to Item 1 or 2.   The anisotropic optical film according to claim 1, wherein the anisotropic light diffusion layer has a thickness of 10 μm to 200 μm.   The anisotropic optical film according to claim 1, wherein a maximum linear transmittance of the anisotropic light diffusion layer is 30% or more and less than 80%.   The absolute value of the difference between the scattering center axis angle of the first columnar structure and the scattering center axis angle of the second columnar structure is 0 ° to 30 °. The anisotropic optical film of any one of these.   The anisotropic optical according to any one of claims 1 to 6, wherein the MD direction diffusion width is 30 ° or more and less than 70 °, and the TD direction diffusion width is 10 ° or more and less than 30 °. the film. On the base material, a coating process for coating the anisotropic light diffusion layer forming composition and providing a coating film;
Curing by irradiation of light from above the coating film, a first structure forming step,
After the first structure forming step, including a second structure forming step of continuously curing by irradiation with light rays,
Of the first structure forming step and the second structure forming step, one step is cured by irradiation with a unidirectional diffused light, and the other step is cured by irradiation with parallel light. The manufacturing method of the anisotropic optical film of any one of Claims 1-7.   The one-way diffused light in the first structure forming step or the second structure forming step is a diffused light obtained via a directional diffusion element, and the aspect ratio of the diffused light is 2 or more The manufacturing method according to claim 8, wherein the manufacturing method is characterized.