JP6902895B2 - Anisotropic optical film and its manufacturing method - Google Patents

Description

The present invention relates to an anisotropic optical film in which the diffusivity of transmitted light changes depending on the angle of incident light and a method for producing the same.

Light diffusing members (light diffusing members) are used not only in lighting equipment and building materials, but also in display devices. Examples of this display device include a liquid crystal display device (LCD), an organic electroluminescence element (organic EL), and the like. The light diffusion manifestation mechanism of the light diffusion member includes scattering due to irregularities formed on the surface (surface scattering), scattering due to the difference in refractive index between the matrix resin and the fine particles dispersed therein (internal scattering), and surface scattering. It may be due to both internal scattering. However, these light diffusing members are generally isotropic in their diffusing performance, and even if the incident light angle is slightly changed, the diffusing characteristics of the transmitted light do not differ significantly.

On the other hand, an anisotropic optical film capable of strongly diffusing incident light in a certain angle region and transmitting incident light at other angles, that is, capable of changing the amount of linearly transmitted light according to the incident light angle. Are known. In such an anisotropic optical film, a set of a plurality of rod-shaped cured regions extending in parallel to a predetermined direction P inside a resin layer made of a cured product of a composition containing a photopolymerizable compound. An anisotropic diffusion medium forming a body is disclosed (see, for example, Patent Document 1). Hereinafter, in the present specification, the structure of an anisotropic optical film in which an aggregate of a plurality of rod-shaped cured regions extending parallel to a predetermined direction P is formed as described in Patent Document 1. It 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, it is referred to as a flow direction in the film manufacturing process (hereinafter, referred to as "MD direction"). , The same diffusion is shown in the width direction of the film perpendicular to the MD direction (hereinafter, referred to as “TD direction”). That is, the diffusion of the pillar structure in the anisotropic optical film exhibits isotropic properties. Therefore, in the anisotropic optical film having a pillar structure, a sudden change in brightness and glare are unlikely to occur.

On the other hand, as an anisotropic optical film, an anisotropic one or a plurality of plate-shaped cured regions are formed inside a resin layer made of a cured product of a composition containing a photopolymerizable compound instead of the pillar structure. By using an anisotropic 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 the present specification, the structure of the anisotropic optical film in which an aggregate of one or a plurality of plate-shaped cured regions is formed as described in Patent Document 2 will be referred to as a “louver structure”. ..

On the other hand, it solves the problems of the anisotropic optical film with a pillar structure and the anisotropic optical film with a louver structure, has good incident light angle dependence in light transmission and diffusion, and widens the diffusion region. In order to make it wider, for example, Patent Document 3 discloses an anisotropic optical film in which an anisotropic light diffusing layer having a pillar structure (corresponding to the “column structure” in Patent Document 3) and an anisotropic light diffusing layer having a louver structure are laminated. Has been done.

Japanese Unexamined Patent Publication No. 2005-265915 Japanese Patent No. 4802707 Japanese Unexamined Patent Publication No. 2012-141593

However, the pillar-structured anisotropic optical film has a low linear transmittance in a non-diffuse region, which is an incident light angle range with a high linear transmittance, and an incident light angle range with a low linear transmittance (that is, 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 a louver structure, when light is incident on the film from above to below, different diffusion is exhibited in the MD direction and the TD direction. That is, the diffusion of the louver structure in the anisotropic optical film shows anisotropicity. Specifically, for example, if the width of the diffusion region (diffusion width) is wider than that of the pillar structure in the MD direction, the diffusion width is narrower than that of 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, there is a problem that light interference is likely to occur and glare is likely to occur as a result of a sudden change in brightness in the TD direction. is there.

However, the conventional anisotropic optical film 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. Further, in the louver structure, the diffusion in the MD direction is wider than that in the pillar, but the diffusion region in the TD direction is narrow, a sudden change in the brightness in the TD direction occurs, and light interference is likely to occur, causing glare. ..

Further, in the anisotropic optical film in which the anisotropic light diffusing layer having a pillar structure and the anisotropic light diffusing layer having a louver structure are laminated, which is described in Patent Document 3, a sudden change in brightness or glare may occur. .. Further, since the step of laminating the anisotropic light diffusing layer having a pillar structure and the anisotropic light diffusing layer having a louver structure is indispensable, the 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 drawbacks of the pillar structure and the louver structure. That is, the transmittance in the non-diffusion region is improved as compared with the pillar structure, the diffusion angle range in the MD direction is expanded, the diffusion angle range in the TD direction is also expanded as compared with the louver structure, and the brightness changes abruptly. It is an object of the present invention to provide an anisotropic optical film capable of solving problems such as glare and glare.

The present inventors have conducted diligent research and found that the above-mentioned 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 changes depending on the angle of incident light.
The anisotropic light diffusion layer is
A first anisotropic light diffusing layer having a matrix region and a plurality of first columnar structures and having a first surface and an intermediate surface,
A second anisotropic light diffusion layer continuous with the first anisotropic light diffusion layer on the intermediate surface, which has a matrix region, a plurality of second columnar structures, and a plurality of first columnar structures, and is a second. With a second anisotropic light diffusing layer having a surface of
The intermediate surface is a position where the layer thickness of the first anisotropic light diffusing layer and the second anisotropic light diffusing layer exceeds 20% from the first surface.
The first columnar structure is configured and oriented toward the second surface of the first said from the first surface of the anisotropic light-diffusing layer of the second anisotropic light-diffusing layer,
The second columnar structure is formed so as to be oriented from the intermediate surface to the second surface.
The first columnar structure becomes discontinuous on the first surface and the second surface.
The second columnar structure is an anisotropic optical film that is discontinuous on the second surface.
The present invention (2)
The aspect ratio of the average minor axis to the average major axis in one of the first columnar structure and the second columnar structure is 2 or more.
The anisotropic optical film of the invention (1), wherein the aspect ratio of the average minor axis to the average major axis of the first columnar structure and the other of the second columnar structure is less than 2. Is.
The present invention (3)
The average minor axis and the average major axis of 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 first columnar structure and the other of the second columnar structure have an average minor axis and an average major axis of 0.5 μm to 5.0 μm and 0.5 μm to 8.0 μm, respectively. The anisotropic optical film of the invention (1) or (2).
The present invention (4)
The anisotropic optical film according to any one of the inventions (1) to (3), characterized in that the thickness of the anisotropic light diffusion layer is 10 μm to 200 μm.
The present invention (5)
Maximum linear transmittance, and less than 80% 30%, which is one of the anisotropic optical film of the invention (1) to (4).
The present invention (6)
The invention (1), wherein 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 according to any one of (5) to (5).
The present invention (7)
Anisotropic optics according to any one of the inventions (1) to (6), wherein the diffusion width in the MD direction is 30 ° or more and less than 70 °, and the diffusion width in the TD direction is 10 ° or more and less than 30 °. It is a film.
The present invention (8)
A coating process in which a composition for forming an anisotropic light diffusing layer is applied onto a base material to provide a coating film, and
A first structure forming step in which a mask film is laminated on the coating film and then cured by irradiation with light rays from above.
After the first structure forming step, a second structure forming step of continuously curing by irradiation with light rays is included.
Of the first structure forming step and the second structure forming step, one step is cured by irradiation with one-way diffused light rays, and the other step is cured by irradiation with parallel rays. , The method for producing an anisotropic optical film according to any one of the inventions (1) to (7).
The present invention (9)
The one-way diffused ray in the first structure forming step or the second structure forming step is a diffused ray obtained through a directional diffusing element, and the aspect ratio of the diffused ray is 2 or more. The production method according to the invention (8), which is characterized by the above-mentioned invention.

According to the anisotropic optical film of the present invention, it is possible to make up for the shortcomings of the pillar structure and the louver structure, and the transmittance in the non-diffusion region is improved and the diffusion angle in the MD direction is improved as compared with the pillar structure. The range can be expanded, the diffusion angle range in the TD direction can be expanded as compared with the louver structure, and sudden changes in brightness and glare can be eliminated. In addition, the defects of both structures can be compensated for without laminating the layers, so that 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 region of a pillar structure and a louver structure, and the state of the transmitted light incident on these anisotropic optical films. It is explanatory drawing which shows the evaluation method of the light diffusivity of an anisotropic optical film. It is a graph which shows the relationship between the incident light angle to the anisotropic optical film of the pillar structure and the louver structure shown in FIG. 1 and the linear transmittance. It is a graph for demonstrating a diffusion region and a non-diffusion region. It is a perspective view which shows an example of the structure of the anisotropic light diffusing layer 110 and 120 in the anisotropic optical film 100 which concerns on this embodiment. FIG. A is a plan view showing an example of the configuration of an anisotropic light diffusing layer having a louver structure, and FIG. B is a plan view B showing an example of the configuration of an anisotropic light diffusing layer having a hybrid structure. It is a perspective view which shows an example of the structure of the anisotropic light diffusing layer 210 and 220 in the aspect of the anisotropic optical film 200. FIG. A is a plan view A showing an example of the configuration of an anisotropic light diffusing layer having a louver structure in the aspect of the anisotropic optical film 200, and FIG. B is a plan view B showing an example of the structure of an anisotropic light diffusing layer having a hybrid structure. It is a perspective view which shows an example of the structure of the anisotropic light diffusing layer 310 and 320 in the aspect of the anisotropic optical film 300. FIG. A is a plan view A showing an example of the configuration of an anisotropic light diffusing layer having a pillar structure in the aspect of the anisotropic optical film 300, and FIG. B is a plan view B showing an example of the structure of an anisotropic light diffusing layer having a hybrid structure. It is a schematic diagram which shows the outline of the columnar region 213 and 223 which grow according to the manufacturing process of the anisotropic optical film 200. It is a schematic diagram which shows the outline of the columnar region 313 and 323 which grows according to the manufacturing process of the anisotropic optical film 300. It is a three-dimensional polar coordinate display for explaining the scattering center axis in an anisotropic light diffusion layer. 3 is a cross-sectional photograph of the anisotropic optical film according to Example 4 in the MD direction and the TD direction. 3 is a cross-sectional photograph of the anisotropic optical film according to Example 10 in the MD direction and the TD direction. It is a graph for demonstrating the evaluation method of the rapid change of the 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 local difference in the refractive index of the material constituting the anisotropic optical film according to the present invention, as compared with the other. It is a relative indicator of 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 diffusivity coincides with the incident light angle of light having substantially symmetry with the incident light angle as a boundary when the incident light angle on the anisotropic optical film is changed. means. “Having substantially symmetry” means that the optical characteristics (“optical profile” described later) do not have strict symmetry when the scattering center axis has an inclination with respect to the normal direction of the film. Because. The central axis of scattering can 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 by changing the incident light angle. Can be done.

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

Further, in the present invention, both "scattering" and "diffusion" are used without distinction, and both have the same meaning. Further, the meanings of "photopolymerization" and "photocuring" are that the photopolymerizable compound undergoes a polymerization reaction by light, and both are used synonymously.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in this specification and drawing, the components with the same reference numerals shall have substantially the same structure or function.

<<< Structure and characteristics of anisotropic optical film >>>
As a premise for explaining the anisotropic optical film according to the present embodiment with reference to FIGS. 1 to 4, a single-layer anisotropic optical film according to the prior art (the “anisotropic light diffusion layer” referred to in the present embodiment is further used. The structure and characteristics of the anisotropic optical film) will be described.

FIG. 1 is a schematic view showing an example of the structure of a single-layer anisotropic optical film having columnar regions of 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 diffusivity of the anisotropic optical film. FIG. 3 is a graph showing the relationship between the incident light angle of the pillar structure and the louver structure shown in FIG. 1 on the anisotropic optical film and the linear transmittance. FIG. 4 is a graph for explaining a diffusion region and a non-diffusion region.

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

<< Characteristics of anisotropic optical film >>
The anisotropic optical film having the above-mentioned structure is a light diffusing film having different light diffusivity depending on the incident light angle on the film, that is, a light diffusing film having an incident light angle dependence. The light incident on the anisotropic optical film at a predetermined incident light angle is the orientation direction of regions having different refractive coefficients (for example, the extending direction (orientation direction) of the columnar region 13 in the pillar structure and the plate-like region in the louver structure. If it is substantially parallel to the height direction of 23), diffusion is prioritized, and if it is not parallel to the direction, transmission is prioritized.

Here, the light diffusivity of the anisotropic optical film will be described more specifically with reference to FIGS. 2 and 3. Here, the light diffusivity of the above-mentioned anisotropic optical film 10 having a pillar structure and the anisotropic optical film 20 having a louver structure will be described as an example.

The method for evaluating the light diffusivity is as follows. First, as shown in FIG. 2, the anisotropic optical films 10 and 20 are arranged between the light source 1 and the detector 2. In the present embodiment, the case where the irradiation light I from the light source 1 is incident from the normal direction of the anisotropic optical films 10 and 20 is defined as an incident light angle of 0 °. Further, the anisotropic optical films 10 and 20 are arranged so as 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 travels straight while changing the angle with the straight line L on the sample surface as the central axis. The linear transmittance that penetrates and enters the detector 2 can be measured.

Evaluate the light diffusivity of the anisotropic optical films 10 and 20 when the TD direction (axis in the width direction of the anisotropic optical film) of FIG. 1 is selected as the straight line L of the rotation center shown in FIG. The evaluation result of the obtained light diffusivity is shown in FIG. FIG. 3 shows the incident light angle dependence of the light diffusivity (light scattering property) of the anisotropic optical films 10 and 20 shown in FIG. 1 measured by using the method shown in FIG. The vertical axis of FIG. 3 is the linear transmittance which is an index showing the degree of scattering (in this embodiment, when a predetermined amount of parallel rays is incident, the amount of light emitted from the parallel rays in the same direction as the incident direction). Ratio, more specifically, linear transmittance = amount of light detected by the detector 2 when the anisotropic optical films 10 and 20 are present / amount of light detected by the detector 2 when the anisotropic optical films 10 and 20 are not present) The horizontal axis indicates the angle of incident light on the anisotropic optical films 10 and 20. The solid line in FIG. 3 shows the light diffusivity of the anisotropic optical film 10 having a pillar structure, and the broken line shows the light diffusivity of the anisotropic optical film 20 having a louver structure. The positive and negative angles of the incident light indicate that the directions in which the anisotropic optical films 10 and 20 are rotated are opposite.

As shown in FIG. 3, the anisotropic optical films 10 and 20 have a light diffusive incident light angle dependence in which the linear transmittance changes depending on the incident light angle. Here, the curve showing the light diffusivity of the incident light angle dependence as shown in FIG. 3 is hereinafter referred to as an “optical profile”. The optical profile does not directly express the light diffusivity, but if it is interpreted that the diffusive transmittance increases due to the decrease in the linear transmittance, it generally shows the light diffusivity. It can be said that there is. The normal isotropic light diffusing film shows a mountain-shaped optical profile with a peak near 0 °, but the anisotropic optical films 10 and 20 show a central axis (thickness) direction of the columnar regions 13 and 23. That is, the linear transmittance is once minimized at an incident light angle of ± 5 to 10 ° as compared with the linear transmittance when incident in the direction of the scattering center axis (the incident light angle in this direction is 0 °). As the incident light angle (absolute value) increases, the linear transmittance increases, and the valley-shaped optical profile in which the linear transmittance becomes the maximum value at an incident light angle of ± 45 to 60 ° is shown. As described above, 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 center axis direction, but is diffused in the incident light angle range beyond that. It has the property of weakening and increasing the linear transmittance. Hereinafter, the angular range of the 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 referred to as a diffusion region (the width of this diffusion region is referred to as "diffusion width"), and other incidents. The light angle range is referred to as a non-diffuse region (transmittance region). Here, 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 with reference to FIG. FIG. 4 shows the optical profile of the anisotropic optical film 20 having the louver structure of FIG. 3, and as shown in FIG. 4, the maximum linear transmittance (in the example of FIG. 4, the linear transmittance is about about. 78%) and the minimum linear transmittance (in the example of FIG. 4, the linear transmittance is about 6%) and the intermediate value of 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 the diffused region, and the others (two on the optical profile shown in FIG. 4). The incident light angle range (outside the two incident light angles at the position of the black spot) is the non-diffusing region.

In the anisotropic optical film 10 having a 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 light is substantially the same in the MD direction and the TD direction. 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, even if the incident light angle is changed, the change in light diffusivity (particularly, the optical profile near the boundary between the non-diffusing region and the diffusing region) is relatively gradual, so that the brightness is increased. It has the effect of not causing sudden changes or glare. However, the anisotropic optical film 10 is displayed because the linear transmittance in the non-diffuse region is low, as can be seen by comparing with the optical profile of the anisotropic optical film 20 having a louver structure shown by the broken line in FIG. There is also a problem that the characteristics (brightness, contrast, etc.) are slightly deteriorated. 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 a louver structure, as can be seen from the state of the transmitted light in FIG. 1 (a), the transmitted light has a substantially needle shape, and the transmitted light is emitted in the MD direction and the TD direction. Diffusivity is very different. That is, in the anisotropic optical film 20 having a louver structure, diffusion is anisotropic. Specifically, in the example shown in FIG. 1, the diffusion is wider in the MD direction than in the case of the pillar structure, but is narrower in the TD direction than in the case of the pillar structure. Further, as shown by the broken line in FIG. 3, when the incident light angle is changed, the light diffusivity (particularly, the optical profile near the boundary between the non-diffusing region and the diffusing region) changes (in the case of this embodiment, in the TD direction). When the anisotropic optical film 20 is applied to a display device, it may appear as a sudden change in brightness or glare, which may reduce visibility. In addition, the anisotropic optical film having a louver structure 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 the display characteristics can be improved.

<<< Configuration of anisotropic optical film according to this embodiment >>>
The configuration of the anisotropic optical film 100 according to the present embodiment will be described with reference to FIG. FIG. 5 is a perspective view showing an example of the configuration of the anisotropic light diffusing layers 110 and 120 in the anisotropic optical film 100 according to the present embodiment. In the following, when the anisotropic optical film 100 is used, it may simply indicate the anisotropic light diffusing layer having the anisotropic light diffusing layers 110 and 120.

<< Overall configuration >>
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 diffusing layers 110 and 120 are continuously formed (the anisotropic light diffusing 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 diffusing layer 110 has a matrix region 111 and a plurality of columnar regions 113 (first columnar structure) having a refractive index different from that of the matrix region 111. The anisotropic light diffusing layer 120 has a matrix region 121, and a plurality of columnar regions 113 (first columnar structure) and columnar regions 123 (second columnar structure) having a refractive index different from that of the matrix region 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 ratios (= average major axis / average minor axis) of the average minor axis and the average major axis of the columnar regions 113 and 123 on the surface (or the cross section perpendicular to the orientation direction) of the anisotropic light diffusion layer 110 may be different. Suitable. More specifically, the anisotropic optical film according to the present invention has, in a preferred form, the pillar structure and the louver structure described above inside the anisotropic light diffusion layer.
Here, the cross-sectional shape of the cross section perpendicular to the orientation direction of the columnar regions 113 and 123 is not particularly limited, but when the columnar region 113 has a louver structure, the columnar region 123 may have a pillar structure. Or, when the columnar region 113 has a pillar structure, the columnar region 123 can have a louver structure.

As described above, as a specific configuration of the anisotropic optical film 100 of the present invention, a hybrid structure having an anisotropic light diffusion layer 110 having a plurality of columnar regions 113, a plurality of columnar regions 123, and a plurality of columnar regions 113. It has an anisotropic light diffusing layer 120 and the like. Hereinafter, the anisotropic optical film 100 having such an anisotropic light diffusing layer 110 and an anisotropic light diffusing 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 a louver) depending on the combination of the aspect ratios of the columnar region 113 and the columnar region 123. Structure), but such a form is also within the scope of the present invention.

<< Anisotropic light diffusion layer 110 >>
The anisotropic light diffusing layer 110 has a columnar region 113, and has a light diffusing property in which the linear transmittance changes depending on the incident light angle. Further, the anisotropic light diffusing layer 110 is made of a cured product of a composition containing a photopolymerizable compound, and as shown in FIGS. 5 and 6A, the matrix region 111 and the matrix region 111 have a plurality of refractive indexes different from each other. It has a columnar region 113. The orientation 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 diffusivity. ing. It should be noted that the fact that the central axis of scattering and the orientation direction of the columnar region are parallel does not have to be exactly parallel as long as it satisfies the law of refractive index (Snell's law). Snell's law states that when light is incident from a medium having a refractive index n ₁ to the interface of a medium having a refractive index n ₂ , n ₁ sin θ ₁ = _{between the incident light angle θ 1} and the refraction angle θ _2. The relationship of n ₂ sin θ _{2 is established.} For example, if n ₁ = 1 (air) and n ₂ = 1.51 (anisometric optical film), the orientation direction (refraction angle) of the columnar region is about 19 ° when the incident light angle is 30 °. However, even if the incident light angle and the refraction angle are different in this way, if Snell's law is satisfied, the concept of parallelism is included in this embodiment.

The anisotropic light diffusing layer 110 may have an orientation direction of the columnar region 113 that does not coincide with the film thickness direction (normal direction) of the film. In this case, in the anisotropic light diffusion layer 110, the incident light is strongly diffused in the incident light angle range (diffuse region) close to the 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-diffuse region) beyond that, the diffusion is weakened and the linear transmittance is increased.

<Columnar region 113>
The columnar region 113 according to the present embodiment is provided as a plurality of columnar hardening regions in the matrix region 111, and each columnar region 113 is formed so that the orientation direction is parallel to the scattering center axis. It is a thing. Therefore, the plurality of columnar regions 113 in the same anisotropic light diffusion layer 110 are formed so as to be parallel to each other.

The refractive index of the matrix region 111 may be different from the refractive index of the columnar region 113, but the degree of difference in the refractive index is not particularly limited and is relative. 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. On the contrary, 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, it is preferable that the refractive index at the interface between the matrix region 111 and the columnar region 113 gradually changes. By gradually changing the light, the change in diffusivity 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 changed.

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

As shown in FIG. 6A, the cross-sectional shape of the columnar region 113 perpendicular to the orientation direction has a minor axis SA and a major axis LA. The minor axis SA and the major axis LA can be confirmed by observing the anisotropic light diffusing layer 110 with an optical microscope (details will be described later). Further, for example, in FIG. 6A, the cross-sectional shape of the columnar region 113 is shown as an elliptical shape, but the cross-sectional shape of the columnar region 113 is not particularly limited. At that time, the minor axis SA and the major axis LA have the same lengths of the minor axis SA and the major axis LA when the cross-sectional shape is, for example, a circular shape, and when they are other figures (subsets of the metric space), the figures. The upper limit of the distance between the two points included in is the major axis LA, and the lower limit is the minor axis SA.

<< Anisotropic light diffusion layer 120 >>
The anisotropic light diffusing layer 120 has a light diffusing property 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 diffusing 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 forming the plurality of columnar regions 113 and 123 over the entire surface of the anisotropic light diffusing layer 120 can be obtained. It will be almost the same. Since the plurality of columnar regions 113 and 123 and the matrix region 121 have an irregular distribution and 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 the present embodiment is provided as a plurality of columnar hardening regions in the matrix region 121, and each columnar region 113 is formed so that the orientation direction is parallel to the scattering center axis. It is a thing. Therefore, the plurality of columnar regions 113 in the same anisotropic light diffusion layer 120 are formed so as 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 of the anisotropic light diffusion layer 110, and detailed description thereof will be omitted (as described above, the columnar region 113 is anisotropic light diffusion. It is a structure that exists continuously across the layer 110 and the anisotropic light diffusion layer 120).

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

The refractive index of the matrix region 121 may be different from the refractive index of the columnar regions 113 and 123, but the degree of difference in the refractive index is not particularly limited and is relative. When the refractive index of the matrix region 121 is lower than the refractive index of the columnar regions 113 and 123, the matrix region 121 becomes a low refractive index region. On the contrary, when the refractive index of the matrix region 121 is higher than the refractive index of the columnar regions 113 and 123, the matrix region 121 becomes a high refractive index region.

The cross-sectional shape of the columnar region 123 perpendicular to the orientation direction 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 as a circular shape, but the cross-sectional shape of the columnar region 123 is not limited to a circular shape, and is an elliptical shape, a polygonal shape, an indefinite shape, and the like. It is not particularly limited, such as a mixture.
At that time, the minor axis SA and the major axis LA have the same lengths of the minor axis SA and the major axis LA when the cross-sectional shape is, for example, a circular shape, and when they are other figures (subsets of the metric space), the figures. The upper limit of the distance between the two points included in is the major axis LA, and the lower limit is the minor axis SA.

<< Shape of columnar region >>
<Aspect ratio of columnar region 113 and columnar region 123>
When either the columnar region 113 or 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 used. ) Is preferably 2 or more, more preferably 2 or more and less than 50, further 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) 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 / The average minor axis) is preferably less than 2, more preferably less than 1.5, and even more preferably less than 1.2.

The anisotropic optical film 100 according to the present embodiment has various characteristics at a higher level in a well-balanced manner by setting both the aspect ratios of the average minor axis and the average major axis of the columnar region 113 and the columnar region 123 to the above-mentioned preferable ranges. It can be an anisotropic optical film.

<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 the upper limit value of the average minor axis of the columnar region 113 and the columnar region 123 can be appropriately combined.

Further, the average value (average major axis) of the major axis LA of either the columnar region 113 or the columnar region 123 is preferably 0.5 μm or more, more preferably 1.0 μm or more, and 1.5 μm or more. It is more preferable to have. On the other hand, the average value (average major axis) of the major axis LA of either the columnar region 113 or the columnar region 123 is preferably 100 μm or less, more preferably 50 μm or less, and more preferably 30 μm or less. More 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, among the columnar region 113 and the columnar region 123, the average value (average major axis) of the other major axis LA in paragraph 0052 is preferably 0.5 μm or more, more preferably 1.0 μm or more. It is more preferably 5 μm or more. On the other hand, of the columnar region 113 and the columnar region 123, the average value (average major axis) of the other major axis LA in paragraph 0052 is preferably 8.0 μm or less, more preferably 5.0 μm or less. It is more preferably 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 paragraph 0052 can be appropriately combined.

The anisotropic optical film 100 according to the present embodiment has various characteristics in a well-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 to the above-mentioned preferable ranges. It can be an optical film.

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 surfaces of the anisotropic light diffusion layer 120 (shown in FIG. 5). The lower end surface 129) may be observed with a microscope, and the minor axis SA and the major axis LA of 100 arbitrarily selected columnar regions 113 and columnar regions 123 may be measured, and the average value thereof may be obtained. 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.

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

<< Region where columnar regions 113 and 123 are formed >>
The columnar region 113 is formed on both the anisotropic light diffusion layers 110 and 120. The total thickness of the anisotropic light diffusing 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 diffusing layer 110 and the anisotropic light diffusing layer 120 toward the lower end surface 129 of the anisotropic light diffusing layer 120. The columnar region 123 is formed from the upper end surface 119 of the anisotropic light diffusing layer 110 to the lower end surface 129 of the anisotropic light diffusing layer 120 from a position exceeding 20% of the total thickness of the anisotropic light diffusing layer 110 and 120. It is preferable (in other words, the anisotropic light diffusing layer 110 is preferably more than 20% of the total thickness). 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 exceeds 40% of the total thickness of the anisotropic light diffusion layers 110 and 120. (In other words, the anisotropic light diffusing 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 diffusing layer 110 and the anisotropic light diffusing layer 120 is preferably 10 μm to 200 μm, more preferably 20 μm or more and less than 100 μm, and 20 μm or more and less than 50 μm. It is more preferable to have. When the thickness exceeds 200 μm, not only the material cost is higher, but also the cost for UV irradiation is increased, which is not only costly, but also the increase in diffusivity in the thickness direction of the anisotropic light diffusing layer causes image blurring. And the contrast is likely to decrease. Further, when the thickness is less than 10 μm, it may be difficult to make the light diffusivity and light condensing property sufficient. In the present invention, by setting the thickness of the anisotropic light diffusing layer within the specified range, the problem of cost is reduced, the light diffusing property and the light condensing property are excellent, and the thickness direction of the anisotropic light diffusing layer Due to the decrease in light diffusivity, image blurring is less likely to occur, and contrast can be improved.

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

<Linear transmittance>
Here, if the linear transmittance of the light incident on the anisotropic optical films 100 (anisometric light diffusing layers 110 and 120) at the incident light angle at which the linear transmittance is maximized is defined as the "maximum linear transmittance", it is different. The sex optical film 100 (anisometric 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.

The linear transmittance of the light incident on the anisotropic light diffusing layers 110 and 120 at the incident light angle at which the linear transmittance is minimized can be defined as the "minimum linear transmittance".

By setting the maximum linear transmittance of the anisotropic optical film 100 to the above range, it is possible to obtain an appropriate anisotropy, so that the applicable range of the anisotropic optical film 100 can be widened. For example, when the anisotropic optical film 100 is used for the display device, if the anisotropy is too strong, the light diffusing / condensing property in the MD direction is extremely excellent, but the light diffusing / condensing property in the TD direction is extremely excellent. There is a problem that the sex tends to be insufficient. Since the anisotropic optical film 100 according to the present embodiment has the above-mentioned maximum linear transmittance, it maintains excellent light diffusing / condensing property in the MD direction and diffuses light in the TD direction. It has sufficient light-collecting property.

Here, the amount of linear transmitted light 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 and the CC axis shown in FIGS. 6A and 6B coincide with each other (normal direction is 0). °). An optical profile can be obtained from the obtained data, and the maximum linear transmittance and the minimum linear transmittance can be obtained from this optical profile.

Further, the maximum linear transmittance and the minimum linear transmittance in the anisotropic optical film 100 (anisotropic light diffusing layers 110 and 120) can be adjusted by design parameters at the time of manufacture. Examples of parameters include the composition of the coating film, the film thickness of the coating film, the temperature applied to the coating film at the time of 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 blending the constituent components. In terms of design parameters, the thicker the film thickness, the lower the maximum linear transmittance and the minimum linear transmittance tend to be, and the thinner the film thickness, the higher the maximum linear transmittance. The higher the temperature, the lower the maximum linear transmittance and the minimum linear transmittance tend to be, and the lower the temperature, the higher the maximum linear transmittance. By combining these parameters, it is possible to appropriately adjust each of the maximum linear transmittance and the minimum linear transmittance.

<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. The two incident light angles with respect to the linear transmittance of this 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 values of the two intersections have 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 is the diffusion width, which is the angular range of the region. When the values of the two intersections are both positive, the difference between the larger value minus the smaller value is the diffusion width, which is the angular 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 which is the angular range of the incident light angle.

In the anisotropic optical film 100, the width (diffusion width) of the diffusion region, which is the angular range of the 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 in the MD direction. , 20 ° or more and less than 70 °, more preferably 30 ° or more and less than 70 °, and even more 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 °. If it is out of the specified range, that is, if the diffusion width is too wide, the light-collecting property is weakened, and if the diffusion width is too narrow, the diffusivity is weakened and the displayability and visibility are deteriorated. Resulting in. That is, in the present invention, when the diffusion width is within the specified range, the diffusivity and the light-collecting property are balanced, and it is possible to further enhance the effect of suppressing abrupt changes in brightness and glare.

<Scattering center axis>
Next, the scattering central 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, and as described above, the scattering central axis has a light diffusivity when the incident light angle to the anisotropic light diffusing layer is changed. It means a direction that coincides with the incident light angle of light having substantially symmetry with the boundary of light. The incident light angle at this time is a substantially central portion (central portion of the diffusion region) sandwiched between the minimum values in this optical profile 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 center axis has a polar angle θ and an azimuth angle when the surfaces of the anisotropic light diffusion layers 110 and 120 are xy planes 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 center axis projected on the surface of the anisotropic light diffusion layer.

Here, the anisotropic light diffusion layer 110 has a columnar region 113, and the anisotropic light diffusion layer 120 has a columnar region 113 and a columnar region 123 (the columnar region 113 has the anisotropic light diffusion layer 110 and the anisotropic light diffusion layer 120). Exists across). The polar angle θ (−90 ° <θ <90 °) formed by the normal (z-axis shown in FIG. 13) of the anisotropic light diffusing layers (anisular light diffusing layers 110 and 120) and the columnar region 113 (columnar region 123). Is defined as the scattering center axis angle in this embodiment, and 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 between the scattering center axis angles to the above range, the effect of the present invention can be further enhanced. In order to realize this effect more effectively, it is more preferable that 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 0 ° or more and 20 ° or less. It is more preferably 10 ° or more and 20 ° or less. The scattering central axis angles of the columnar region 113 and the columnar region 123 can be adjusted to desired angles by changing the direction of the light rays irradiating the composition containing the sheet-shaped photopolymerizable compound at the time of producing them. can do. The positive and negative of the scattering center axis angle are the predetermined axis of symmetry in the plane direction of the anisotropic light diffusion layers 110 and 120 (for example, the 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. With respect to the plane passing through both the normals of 110 and 120, the case where the scattering center axis is inclined to one side is defined as +, and the case where the scattering center axis is inclined to the other side is defined as-.

Further, in addition to the absolute value of the difference in the scattering center axis angle (extreme angle) satisfying 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. This makes it possible to further expand the width of the diffusion region without lowering the linear transmittance in the non-diffusion region of the anisotropic optical film 100.

Here, each of the anisotropic light diffusing layers 110 and 120 may have a plurality of columnar region groups having different slopes (a set of columnar regions having the same slope) in a single layer. As described above, when there are a plurality of columnar region groups having different inclinations in the single layer, the scattering central axes are also a plurality of elements corresponding to the inclinations of the columnar region groups. When there are a plurality of scattering center axes, at least one of the plurality of scattering center axes may satisfy the above-mentioned scattering center axis angle condition. For example, when the anisotropic light diffusing layer 110 has two scattering central axes P1 and P2 and the anisotropic light diffusing layer 120 has four scattering central axes P1, P2, P3 and P4, at least P1 and P2. It is preferable that the absolute value of the difference between the scattering center axis angle of either one and the scattering center axis angle of at least one of P3 and P4 is 0 ° or more and 30 ° or less. It is more preferable that the lower limit of the absolute value of the difference between the scattering center axis angles is 5 °. On the other hand, the upper limit of the absolute value of the difference between the scattering center axis angles is more preferably 20 °, further preferably 15 °.

Further, 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 °. If the scattering center axis angle is larger 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 larger than + 60 ° or less than -60 °, it is necessary to irradiate the composition containing the photopolymerizable compound provided in the form of a sheet with light from a deep inclination in the manufacturing process. This is not preferable because the absorption efficiency of the irradiation light is poor and it is disadvantageous in manufacturing.

<Refractive index>
The anisotropic light diffusing layers 110 and 120 are obtained by curing a composition containing a photopolymerizable compound, and the following combinations can be used as this composition.
(1) Those using a single photopolymerizable compound described later (2) Those using a mixture of a plurality of photopolymerizable compounds described later (3) Not having photopolymerizability with a single or a plurality of photopolymerizable compounds Used by mixing with a polymer compound

In any of the above combinations, it is presumed that micron-order fine structures having different refractive indexes are formed in the anisotropic light diffusing layers 110 and 120 by light irradiation, which is a peculiarity shown in the present embodiment. It is considered that the anisotropic light diffusion characteristic is exhibited. Therefore, in (1) above, it is preferable that the change in refractive index before and after photopolymerization is large, and in (2) and (3), it is preferable to combine a plurality of materials having different refractive indexes. The change or difference in the refractive index here specifically indicates a change or difference of 0.01 or more, preferably 0.05 or more, and more preferably 0.10 or more.

<Other forms of anisotropic optical film>
The anisotropic optical film 100 according to the present embodiment has an anisotropic light diffusing layer (in this embodiment, a continuous layer composed of the anisotropic light diffusing 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. , And a haze value (JIS K7136) of 3.0 or less, more preferably 1.0 or less, and most preferably 0.5 or less can be preferably used. Specifically, as the translucent substrate, a transparent plastic film, a glass plate, or the like can be used, but the plastic film is preferable in that it is thin, light, hard to break, and excellent in productivity. Specific examples include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), triacetyl cellulose (TAC), polycarbonate (PC), polyether sulfone (PES), cellophane, polyethylene (PE), polypropylene (PP), and polyvinyl. Examples thereof include alcohol (PVA) and cycloolefin resin, and these can be used alone or mixed, and further laminated. Further, the thickness of the translucent substrate is preferably 1 μm to 5 mm, more preferably 10 to 500 μm, and further preferably 50 to 150 μm in consideration of application and productivity.

Further, the anisotropic optical film according to the present invention may be an anisotropic optical film in which another layer is provided on one surface of the anisotropic light diffusing layer 110 side or 120 side. Examples of 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, an electromagnetic wave shield layer, and the like. .. Other layers may be laminated sequentially. Further, another layer may be laminated on both the surfaces of the anisotropic light diffusion layer 110 side and / or 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 producing anisotropic optical film according to this embodiment >>>
The configuration of the anisotropic optical film 100 according to the present embodiment has been described in detail above, and subsequently, a method for manufacturing the anisotropic optical film 100 having such a configuration will be described.

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

<< Raw material for anisotropic light diffusion layer >>
The raw materials of the anisotropic light diffusing layers (anisometric light diffusing layers 110 and 120) will be described in the order of (1) photopolymerizable compound, (2) photoinitiator, (3) blending amount, and other optional components.

<Photopolymerizable compound>
The photopolymerizable compound which is a material for forming the anisotropic light diffusion layers 110 and 120 according to the present embodiment is photopolymerizable selected from macromonomers, polymers, oligomers and monomers having radical-polymerizable or cationically polymerizable functional groups. A material composed of a compound and a photoinitiator, which polymerizes and cures when irradiated with ultraviolet rays and / or visible light. Here, even if there is only one type of material for forming the anisotropic light diffusing layer contained in the anisotropic optical film 100, a difference in refractive index occurs due to a difference in density. This is because the curing rate becomes faster in the portion where the UV irradiation intensity is strong, so that the polymerization / curing material moves around the curing region, and as a result, a region having a high refractive index and a region having a low refractive index are formed. .. The (meth) acrylate means that either acrylate or methacrylate may be used.

The radically polymerizable compound mainly contains one or more unsaturated double bonds in the molecule, and specifically, epoxy acrylate, urethane acrylate, polyester acrylate, polyether acrylate, polybutadiene acrylate, silicone acrylate and the like. 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, trimethyl propantriacrylate, Examples thereof include acrylate monomers such as EO-modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropanetetraacrylate, and dipentaerythritol hexaacrylate. Further, these compounds may be used individually or in combination of two or more. Although methacrylate can be used in the same manner, acrylate is generally preferable to methacrylate because it has a faster photopolymerization rate.

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

Further examples of the compound having an epoxy group include 3,4-epoxycyclohexylmethyl-3', 4'-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy). Cyclohexane-meth-dioxane, di (3,4-epoxycyclohexylmethyl) adipate, di (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl-3', 4' -Epoxy-6'-methylcyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di (3,4-epoxycyclohexylmethyl) ether, ethylenebis (3,4-epoxy) Cyclohexanecarboxylate), lactone-modified 3,4-epoxycyclohexylmethyl-3', 4'-epoxycyclohexanecarboxylate, tetra (3,4-epoxycyclohexylmethyl) butanetetracarboxylate, di (3,4-epoxycyclohexylmethyl) ) -4,5-Epoxy Tetrahydrophthalate and other alicyclic epoxy compounds can also be mentioned, but are not limited thereto.

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, and trimethyl propantri. Examples thereof include vinyl ether and propenyl ether propylene carbonate, but the present invention is not limited thereto. The vinyl ether compound is generally cationically polymerizable, but radical polymerization is also possible by combining it with acrylate.

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 cationically polymerizable compounds may be used alone or in combination of two or more. The photopolymerizable compound is not limited to the above. Further, in order to generate a sufficient difference in refractive index, a fluorine atom (F) may be introduced into the photopolymerizable compound in order to reduce the refractive index, and in order to increase the refractive index, A sulfur atom (S), a bromine atom (Br), and various metal atoms may be introduced. Further, as disclosed in Japanese Patent Application Laid-Open No. 2005-514487, ultrafine particles composed of metal oxides 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 acrylic group, a methacryl group, or an epoxy group introduced on the surface to the above-mentioned 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. The photopolymerizable compound having a silicone skeleton is oriented according to its structure (mainly ether bond), polymerizes and hardens, and forms 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 the photopolymerizable compound having a silicone skeleton, the columnar regions 113 and 123 can be easily tilted, and the light collecting property in the front direction is improved. The low refractive index region corresponds to any 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 amount of the silicone resin, which is a cured product of the photopolymerizable compound having a silicone skeleton, is relatively large. As a result, the central axis of scattering can be further tilted, so that the light collecting property in the front direction is improved. Since the silicone resin contains a large amount of silica (Si) as compared with the compound having no silicone skeleton, the relative of the silicone resin is obtained by using EDS (Energy Dispersion Type X-ray Spectrometer) using this silica as an index. You can check the 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 radically polymerizable functional group include an acryloyl group, a methacryloyl group, an allyl group and the like, and examples of the cationically polymerizable functional group include an epoxy group and an oxetane group. The type and number of these functional groups are not particularly limited, but it is preferable to have a polyfunctional acryloyl group or a methacryloyl group because the more functional groups there are, the higher the crosslink density and the more likely it is that a difference in refractive index occurs. .. Further, a compound having a silicone skeleton may be insufficient in compatibility with other compounds due to its structure, but in such a case, it can be urethaneized to enhance compatibility. In this embodiment, a silicone urethane (meth) acrylate having an acryloyl group or a methacryloyl group at the end 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 in the range of 2,000 to 20,000. When the weight average molecular weight is in the above range, a sufficient photocuring reaction occurs, and the silicone resin existing 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 becomes easy to incline.

As the silicone skeleton, for example, the one represented by the following general formula (1) is applicable. In the general formula (1), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are independently methyl group, alkyl group, fluoroalkyl group, phenyl group, epoxy group, amino group, and carboxyl group, respectively. , Polyether group, acryloyl group, methacryloyl group and other functional groups. Further, in the general formula (1), n is preferably an integer of 1 to 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 having no silicone skeleton, the low refractive index region and the high refractive index region are easily separated and formed, which is anisotropic. Is preferable because the degree of As the compound having no silicone skeleton, a thermoplastic resin and a thermosetting resin can be used in addition to the photopolymerizable compound, and these can also be used in combination. As the photopolymerizable compound, a polymer, oligomer, or monomer having a radically polymerizable or cationically 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 copolymers and modified products thereof. When a thermoplastic resin is used, it is dissolved using a solvent in which the thermoplastic resin is dissolved, and after coating 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 resin, phenol resin, melamine resin, urea resin, unsaturated polyester and its copolymers and modified products. When a thermosetting resin is used, the thermosetting resin is cured by appropriately heating after curing the photopolymerizable compound having a silicone skeleton with ultraviolet rays to form an anisotropic light diffusion layer. The most preferable compound having no 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 because it does not require a thermosetting process like a thermosetting resin.

<Light initiator>
Photoinitiators capable of polymerizing 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, benzyl dimethyl ketal, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenylketone, 2 -Methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanol-1, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1 -On, bis (cyclopentadienyl) -bis (2,6-difluoro-3- (pill-1-yl) titanium, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone -1,2,4,6-trimethylbenzoyldiphenylphosphine oxide and the like can be mentioned. Further, these compounds may be used alone or in combination of two or more.

Further, the photoinitiator of the cationically polymerizable compound is a compound that generates an acid by light irradiation and can polymerize the above-mentioned cationically polymerizable compound by the generated acid, and is generally an onium salt or metallocene. Complexes are preferably used. Examples of the onium salts, diazonium salts, sulfonium salts, iodonium salts, are used phosphonium salts, selenium salts and the like, these _{^{counterions, BF 4 -, PF 6 -}} , AsF 6 -, SbF 6 - anion and the like Used. Specific examples include 4-chlorobenzenediazonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, (4-phenylthiophenyl) diphenylsulfonium hexafluoroantimonate, and (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, triphenylselenium hexafluorophosphate, Examples thereof include, but are not limited to, (η5-isopropylbenzene) (η5-cyclopentadienyl) iron (II) hexafluorophosphate and the like. Further, these compounds may be used individually or in combination of two or more.

<Mixing amount and other optional ingredients>
In the present embodiment, the photoinitiator is 0.01 to 10 parts by weight, preferably 0.1 to 7 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the photopolymerizable compound. It is compounded. This is because if it is less than 0.01 parts by weight, the photocurability is lowered, and if it is blended in excess of 10 parts by weight, only the surface is cured and the internal curability is lowered. This is because it causes inhibition of the formation of. These photoinitiators are usually used by directly dissolving powder in a photopolymerizable compound, but if the solubility is poor, the photoinitiator is previously dissolved in a very small amount of solvent at a high concentration. 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 photopolymerizability. Further, a thermosetting initiator capable of curing the photopolymerizable compound by heating can be used in combination with the photoinitiator. In this case, it can be expected that the polymerization curing of the photopolymerizable compound is further promoted and completed by heating after the photocuring.

In this embodiment, the composition in which the above photopolymerizable compounds are used alone or in a mixture of a plurality of the above photopolymerizable compounds can be cured to form the anisotropic light diffusing layers 110 and 120. The anisotropic light diffusing layers 110 and 120 of the present embodiment can also be formed by curing a mixture of a photopolymerizable compound and a polymer resin having no photocurability. Examples of the polymer resin that can be used here include acrylic resin, styrene resin, styrene-acrylic copolymer, polyurethane resin, polyester resin, epoxy resin, cellulose resin, vinyl acetate resin, vinyl chloride-vinyl acetate copolymer, and the like. Polyvinyl butyral resin and the like can be mentioned. 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. When acrylate is used as the photopolymerizable compound, it is preferable to select from acrylic resin as the polymer resin in terms of compatibility.

The ratio of the photopolymerizable compound having a silicone skeleton to the compound having no silicone skeleton is preferably in the range of 15:85 to 85:15 in terms of mass ratio. More preferably, it is in the range of 30:70 to 70:30. Within this range, phase separation between the low refractive index region and the high refractive index region is likely to proceed, and the columnar region is likely to be inclined. If the ratio of the photopolymerizable compound having a silicone skeleton is less than the lower limit value or more than the upper limit value, phase separation is difficult to proceed and the columnar region is difficult to incline. When silicone, urethane, or (meth) acrylate is used as the photopolymerizable compound having a silicone skeleton, the compatibility with the compound having no silicone skeleton is improved. Thereby, the columnar region can be inclined even if the mixing ratio of the materials is widened.

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

<<< Example 1 of Anisotropy Optical Film >>>
An example of 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 diffusing layer 210 has a columnar region 213 having a louver structure, and has a light diffusing property in which the linear transmittance changes depending on the incident light angle.

<Columnar area 213>
The columnar region 213 according to the present embodiment is provided as a plurality of columnar hardening regions in the matrix region 211, and each columnar region 213 is formed so that the orientation direction is parallel to the scattering center axis. It is a thing. Therefore, the plurality of columnar regions 213 in the same anisotropic light diffusion layer 210 are formed so as 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 of difference in refractive index 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 gradually changes. By gradually changing the light, the change in diffusivity 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 changed.

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

As shown in FIG. 8A, the cross-sectional shape of the columnar region 213 perpendicular to the orientation direction has a minor axis SA and a major axis LA, 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 diffusing 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 changes depending on the incident light angle. Further, as shown in FIG. 8B, the anisotropic light diffusing 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 an 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 diffusing layer 220 can be obtained. 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 cause light interference (rainbow).

<Columnar area 213>
The columnar region 213 according to this embodiment is provided as a plurality of columnar hardening 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. It is a thing. Therefore, the plurality of columnar regions 213 in the same anisotropic light diffusion layer 220 are formed so as 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 area 223>
The columnar region 223 according to this embodiment is provided as a plurality of columnar hardening regions in the matrix region 221, and each columnar region 223 is formed so that the orientation direction is parallel to the scattering center axis. There is. Therefore, the plurality of columnar regions 223 in the same anisotropic light diffusion layer 220 are formed so as to be parallel to each other.

The refractive index of the matrix region 221 is different from the refractive index of the columnar regions 213 and 223. The degree of difference in refractive index is not particularly limited and is relative. When the refractive index of the matrix region 221 is lower than the refractive index of the columnar regions 213 and 223, the matrix region 221 becomes a low refractive index region. On the contrary, when the refractive index of the matrix region 221 is higher than the refractive index of the columnar regions 213 and 223, the matrix region 221 becomes a high refractive index region.

As shown in FIG. 8B, the cross-sectional shape of the columnar region 223, which is a pillar structure, perpendicular to the orientation direction has a minor axis SA and a major axis LA, 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 columnar region 213 and 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 this aspect has various characteristics in a well-balanced manner at a higher level by setting both the aspect ratios of the average minor axis and the average major axis of the columnar region 213 and the columnar region 223 to the above-mentioned preferable ranges. It can be an anisotropic optical film.

<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 minor 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 It is 0.0 μm.

The anisotropic optical film 200 according to the present embodiment has various characteristics in a well-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 to the above-mentioned preferable ranges. It can be an optical film.

<<< Example 2 of Anisotropy 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 diffusing layer 310 has a columnar region 313 having a pillar structure, and has a light diffusing property in which the linear transmittance changes depending on the joining light angle.

<Columnar area 313>
The columnar region 313 according to this embodiment is provided as a plurality of columnar hardening regions in the matrix region 311, and each columnar region 313 is formed so that the orientation direction is parallel to the scattering center axis. It is a thing. Therefore, the plurality of columnar regions 313 in the same anisotropic light diffusion layer 310 are formed so as 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 of difference in refractive index 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 becomes a low refractive index region. On the contrary, 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, it is preferable that the refractive index at the interface between the matrix region 311 and the columnar region 313 gradually changes. By gradually changing the light, the change in diffusivity 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 changed.

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

As shown in FIG. 10A, the cross-sectional shape of the columnar region 313 perpendicular to the orientation direction 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.

<< Anisotropic light diffusion layer 320 >>
The anisotropic light diffusing layer 320 has a columnar region 313 having a pillar structure and a columnar region 323 having a louver structure coexisting, and has light diffusivity in which the linear transmittance changes depending on the incident light angle. Further, as shown in FIG. 10B, the anisotropic light diffusing layer 320 is made of a cured product of a composition containing a photopolymerizable compound, and the matrix region 321 and a 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 an 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 diffusing layer 320 can be obtained. It will be almost the same. Since the plurality of columnar regions 313 and 323 and the matrix region 321 have an irregular distribution and shape, the anisotropic light diffusion layer 320 according to this embodiment is less likely to cause light interference (rainbow).

<Columnar area 313>
The columnar region 313 according to this embodiment is provided as a plurality of columnar hardening regions in the matrix region 321, and each columnar region 313 is formed so that the orientation direction is parallel to the scattering center axis. It is a thing. Therefore, the plurality of columnar regions 313 in the same anisotropic light diffusion layer 320 are formed so as 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 of the anisotropic light diffusion layer 310, and detailed description thereof will be omitted (as described above, the columnar region 313 is anisotropic light diffusion. It is a structure that exists continuously across the layer 310 and the anisotropic light diffusion layer 320).

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

The refractive index of the matrix region 321 is different from the refractive index of the columnar regions 313 and 323. The degree of difference in refractive index is not particularly limited and is relative. When the refractive index of the matrix region 321 is lower than the refractive index of the columnar regions 313 and 323, the matrix region 321 becomes a low refractive index region. On the contrary, when the refractive index of the matrix region 321 is higher than the refractive index 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 of the columnar region 323 having a louver structure perpendicular to the orientation direction is an elliptical shape, and the average value of the minor axis SA (average minor axis) and the average value of the major axis LA (average major axis). The aspect ratio (= average major axis / average minor axis) of 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 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 less than 2.

Further, 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 in a well-balanced manner at a higher level by setting both the aspect ratios of the average minor axis and the average major axis of the columnar region 313 and the columnar region 323 to the above-mentioned preferable ranges. It can be an anisotropic optical film.

<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 It is 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 anisotropy having various characteristics at a higher level in a well-balanced manner by setting both the average minor axis and the average major axis of the columnar region 313 and the columnar region 323 to the above-mentioned preferable ranges. It can be an optical film.

<< Manufacturing process of anisotropic optical film >>
Next, the process (manufacturing method) of the anisotropic optical films 200 and 300 of the present embodiment will be described with reference to FIGS. 11 and 12. 11 and 12 show an outline of the manufacturing process of the anisotropic optical films 200 and 300 of the present embodiment, columnar regions 213 and 223 growing according to the manufacturing process of the anisotropic optical films 200 and 300, and 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, may be referred to as a "photocurable composition") is applied onto an appropriate base material (base material) such as a transparent PET film or in the form of a sheet. A photocurable composition layer is provided by forming a film. The photocurable composition layer is dried as necessary to volatilize the solvent, and then the photocurable composition layer is irradiated with light to cause the anisotropic light diffusion layers 210 and 220 and the anisotropic light diffusion. An anisotropic light diffusing layer having the layers 310 and 320 as one layer can be produced. Hereinafter, those obtained by applying the photocurable composition on a substrate or providing it in the form of a sheet are referred to as coating films 250 and 350.

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

<Process 1: Coating process>
In step 1, as a method of providing the composition containing the photopolymerizable compound in the form of a sheet on the substrate, a usual 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. , Die coating and other coatings, intaglio printing such as gravure printing, and stencil printing such as screen printing can be used. If the composition has a low viscosity, a weir of a certain height may be provided around the substrate, and the composition may be cast in the weir surrounded by the weir.

<Step 2: Mask film laminating step (optional)>
In step 2, in order to prevent oxygen inhibition of the photocurable composition layer and efficiently form the columnar region 213 which is a feature of the anisotropic light diffusion layer 210 according to the present embodiment, the light of the photocurable composition layer is applied. It is preferable to laminate a mask film (hereinafter, simply referred to as a mask or the like) that adheres to the irradiation side and locally changes the irradiation intensity of light. The material of the mask is not particularly limited, and for example, an ordinary transparent plastic film or the like may be used, but a light-absorbing filler such as carbon is dispersed in the matrix, and a part of the incident light is carbon. Although it is absorbed, the opening may be configured to allow sufficient light to pass through. Such a matrix includes transparent plastics such as PET, TAC, PVAC, PVA, acrylic and polyethylene, inorganic substances 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 contain a pigment that absorbs ultraviolet rays. When such a mask is not used, it is possible to prevent oxygen inhibition of the photocurable composition layer by irradiating with light 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 columnar region 213. As described above, the light irradiation through the mask or the transparent film is effective for producing the anisotropic light diffusing layer 210 according to the present embodiment.

<Step 3: Step of forming an anisotropic light diffusing layer>
Next, the apparatus used in the anisotropic light diffusing layer forming step will be described with reference to FIG. 11, and the specific forming process of the anisotropic light diffusing layer will be described.

〔apparatus〕
First, as shown in FIG. 11, the anisotropic optical film 200 is mainly produced 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 and the moving direction are controlled by the motor driver. More specifically, in FIG. 11, the coating film 250 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 is for irradiating the coating film 250 with the emitted light to cause phase separation and curing the columnar regions 213 and 223 to form the anisotropic light diffusion layers 210 and 120. 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, and specifically, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide 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 the photocurable composition layer with light rays parallel to the desired scattering center axis Q. In order to obtain such parallel light D, a point light source is arranged, 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. Just place it. 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 on the coating film 250 (photocurable composition layer).

The light beam irradiating the composition containing the photopolymerizable compound needs to contain a wavelength capable of curing the photopolymerizable compound, and usually light having a wavelength centered on 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 Is. If the illuminance is ^{less than 0.01 mW / cm 2} , it takes a long time to cure, so the production efficiency may deteriorate. If it ^{exceeds 100 mW / cm 2} , the photopolymerizable compound cures too quickly and structure formation occurs. This is because the desired anisotropic diffusion characteristics may not be exhibited.

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

The directional diffusion element 240 may be any one 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 directional diffuser 240 contains a needle-shaped filler having a high aspect ratio, and the needle-shaped filler is placed in the Y direction in the long axis direction. A method of orienting to persist can be adopted. The directional diffusion element 240 can use various methods other than the method using the needle-shaped filler. The parallel light D may be arranged so as to obtain the diffused light E by passing through the directional diffusion element 240. Specific examples of such a directional diffusion element 240 include a lenticular lens and the like.

The light-shielding plate 230 is for blocking the light emitted from the light source and preventing the composition containing the photopolymerizable compound from being irradiated with the light. The material, size, thickness, and the like of the light-shielding plate 230 may be appropriately determined according to the wavelength and intensity of the light emitted from the light source.

Here, as shown in FIG. 11, the directional diffusion element 240 is arranged so as to project from the shielding plate 230 in the direction along the moving direction of the coating film 250. By doing so, there are three regions: the region AR1 in which all the light emitted from the light source by the shielding plate 230 is blocked, the region AR2 in which the diffused light E is irradiated, and the region AR3 in which the parallel light D is irradiated. Regions can be formed.

Hereinafter, a specific process for forming an anisotropic light diffusing layer in each region divided into regions AR1 to AR3 will be described.

(Process of area AR1)
In the process in 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 applied to the coating film 250. At this stage, all of the coating film 250 is located in region AR1. Therefore, 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.

(Step of region AR2: Step of forming anisotropic light diffusing 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 region 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 region AR1 to the region AR2. In the region AR2, the diffused light E is applied to the coating film 250.

When the diffused light E is irradiated on the coating film 250, phase separation starts from the upper surface of the coating film 250. By the irradiation of the diffused light E, the columnar region 213 starts to be formed from the upper surface of the coating film 250 and gradually grows. Along with the formation of the columnar region 213, the 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 the columnar region 213 and the matrix region 211 start to be formed from the upper surface to the lower surface by the phase separation. .. At this point, as shown in the state (c) of FIG. 11, the columnar region 213 and the matrix region 211 do not reach the lower surface, but 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 of being. The intermediate position is not limited to the center or center position between the upper surface and the lower surface, but indicates an arbitrary position in the 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 to the intermediate position of the coating film 250. In the coating film 250, the region from the upper surface to the intermediate position is in a cured state to form a louver structure, and the region from the intermediate position to the lower surface is in an uncured state and no structure is formed. It becomes an unformed state.

Here, in this step, the size (aspect ratio, minor axis SA, major axis LA, etc.) of the columnar region 213 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 diffuser 240 and the coating film 250, the type of the directional diffuser 240, and the like. The size of the columnar region becomes smaller as the distance is shortened, and the size of the columnar region becomes larger as the distance is lengthened. 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 in a form substantially corresponding to the aspect ratio. As the aspect ratio becomes smaller, the diffusion range may become narrower. Therefore, in this embodiment, the aspect ratio is set to 2 or more. The aspect ratio is more preferably 2 or more and less than 50, further 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 diffusing property and the light collecting property are improved.

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

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

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

As shown in the state (d) and the state (e) of FIG. 11, when the parallel light D is irradiated on the coating film 250, further phase separation starts from the intermediate position of the coating film 250 and the columnar region 223. Begins to form and gradually grows. 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 step of the region AR3, the matrix region 221 is also formed along with the formation of the columnar regions 213 and 223, and the columnar regions 213 and 223 and the matrix region 221 reach the lower surface. As described above, in the region from the intermediate position to the lower surface, a hybrid structure in which two types of structures, a louver structure formed by the columnar region 213 and a pillar structure formed by the columnar region 223, coexist is formed. Due to the formation of the hybrid structure, the region from the intermediate position to the lower surface is also cured.

As described above, when the coating film 250 goes through the steps of the region AR2 and the region AR3, 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 and is formed.

In this embodiment, a method using a moving stage is adopted for continuously forming the anisotropic light diffusion layers 210 and 220, but the method is not limited to this, and FIGS. 11 (a) to 11 (a) to ( The upper layer of the coating film is cured by a method such as c) (up to the process of region AR2) as one step and FIGS. 11 (d) to (e) as another step (after the step of region AR3). An anisotropic light-diffusing layer 220 may be formed by forming a square light-diffusing layer 210, and then changing the light irradiation conditions in a state where an uncured layer exists as a lower layer of the coating film, or the like. , The anisotropic optical film 200 according to this embodiment can be formed.

In the present anisotropic light diffusion layer forming step, the total irradiation time of light 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 the present embodiment are obtained by forming a specific internal structure in the photocurable composition layer by irradiating the light with low illuminance for a relatively long time as described above. is there. Therefore, the unreacted monomer component may remain only by such light irradiation, causing stickiness, and there may be a problem in handleability and durability. In such a case, the residual monomer can be polymerized by additionally irradiating light with 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 where the masks are laminated), which is the surface opposite to the first irradiation for forming the anisotropic light diffusion layer of the coating film 250. May be good.

<Example of forming process of anisotropic optical film 300>
The following steps will be described in detail as the steps for forming the anisotropic optical film 300 according to the present embodiment.
(Step 1) A coating step of coating an anisotropic light diffusing layer forming composition on a base material to provide a coating film 350 (Step 2) A mask film laminating step of laminating a mask film on the coating film 350. (Any)
(Step 3) Coating is continuously performed after the first structure forming step (anisometric light diffusion layer 310 forming step) and the first structure forming step in which curing is performed on the coating film 350 by irradiation with parallel light rays. A second structure forming step (anisometric light diffusing layer 320 forming step) in which curing is performed on the film 350 by irradiation with unidirectional diffused light.

<Process 1: Coating process>
In step 1, as a method of providing the composition containing the photopolymerizable compound in the form of a sheet on the substrate, a usual 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. , Die coating and other coatings, intaglio printing such as gravure printing, and stencil printing such as screen printing can be used. If the composition has a low viscosity, a weir of a certain height may be provided around the substrate, and the composition may be cast in the weir surrounded by the weir.

<Step 2: Mask film laminating step (optional)>
In step 2, in order to prevent oxygen inhibition of the photocurable composition layer and efficiently form the columnar region 313 which is a feature of the anisotropic light diffusion layer 310 according to the present embodiment, the light of the photocurable composition layer is applied. It is preferable to laminate a mask film (hereinafter, simply referred to as a mask or the like) that adheres to the irradiation side and locally changes the irradiation intensity of light. The material of the mask is not particularly limited, and for example, an ordinary transparent plastic film or the like may be used, but a light-absorbing filler such as carbon is dispersed in the matrix, and a part of the incident light is carbon. Although it is absorbed, the opening may be configured to allow sufficient light to pass through. Such a matrix includes transparent plastics such as PET, TAC, PVAC, PVA, acrylic and polyethylene, inorganic substances 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 contain a pigment that absorbs ultraviolet rays. When such a mask is not used, it is possible to prevent oxygen inhibition of the photocurable composition layer by irradiating with light 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 columnar region 313. As described above, the light irradiation through the mask or the transparent film is effective for producing the anisotropic light diffusing layer 310 according to the present embodiment.

<Step 3: Step of forming an anisotropic light diffusing layer>
Next, the apparatus used in the anisotropic light diffusing layer forming step will be described with reference to FIG. 12, and the specific forming process of the anisotropic light diffusing layer will be described.

〔apparatus〕
First, as shown in FIG. 12, the anisotropic optical film 300 is mainly produced 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 and the moving direction are controlled by the 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 is for irradiating the coating film 350 with the emitted light to cause phase separation and curing the columnar regions 313 and 323 to form the anisotropic light diffusion layers 310 and 320. 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, and specifically, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, a xenon lamp, or the like can be used.

In particular, in the process of forming the columnar region 313 described later, it is necessary to irradiate the photocurable composition layer with light rays parallel to the desired scattering center axis Q. In order to obtain such parallel light D, a point light source is arranged, 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. Just place it. 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 on the coating film 350 (photocurable composition layer).

The light beam irradiating the composition containing the photopolymerizable compound needs to contain a wavelength capable of curing the photopolymerizable compound, and usually light having a wavelength centered on 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 Is. If the illuminance is ^{less than 0.01 mW / cm 2} , it takes a long time to cure, so the production efficiency may deteriorate. If it ^{exceeds 100 mW / cm 2} , the photopolymerizable compound cures too quickly and structure formation occurs. This is because the desired anisotropic diffusion characteristics may not be exhibited.

The directional diffuser 340 is for imparting directivity to the parallel light D and converting it into diffused light E. A columnar region 323 is formed by irradiating the coating film 350 with diffused light E.

The directional diffusion element 340 may be any one 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 directional diffuser 340 contains a needle-shaped filler having a high aspect ratio, and the needle-shaped filler is placed in the Y direction in the long axis direction. A method of orienting to persist can be adopted. The directional diffusion element 340 can use various methods other than the method using the needle-shaped filler. The parallel light D may be arranged so as to obtain the diffused light E by passing through the directional diffusion element 340. Specific examples of such a directional diffusion element 340 include a lenticular lens and the like.

The light-shielding plate 330 is for blocking the light emitted from the light source and preventing the composition containing the photopolymerizable compound from being irradiated with the light. The material, size, thickness, and the like of the light-shielding plate 330 may be appropriately determined according to the wavelength and intensity of the 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 so, there are three regions: the region AR4 in which all the light emitted from the light source by the shielding plate 330 is blocked, the region AR5 in which the parallel light D is irradiated, and the region AR6 in which the diffused light E is irradiated. Regions can be formed.

Hereinafter, a specific process for forming an anisotropic light diffusing layer in each region divided into regions AR4 to AR6 will be described.

(Process of area AR4)
In the process in 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 on the coating film 350. At this stage, all of the coating film 350 is located in region AR4. Therefore, 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.

(Step of region AR5: Step of forming anisotropic light diffusing 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 region 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 regions, the region AR4 and the region AR5. As the coating film 350 is exposed from the light-shielding plate 330, it moves from the region AR4 to the region AR5. In the region AR5, the parallel light D is applied to the coating film 350.

When the parallel light D is irradiated 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 gradually grows. Along with the formation of the columnar region 313, the 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 the columnar region 313 and the matrix region 311 start to be formed from the upper surface to the lower surface by the phase separation. .. At this point, 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 of being. The intermediate position is not limited to the center or center position between the upper surface and the lower surface, but indicates an arbitrary position in the 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 to the intermediate position of the coating film 350. In the coating film 350, the region from the upper surface to the intermediate position is in a cured state to form a pillar structure, and the region from the intermediate position to the lower surface is in an uncured state and no structure is formed. It becomes an unformed state.

(Step of region AR6: Step of forming anisotropic light diffusing layer 320)
When the coating film 350 is further moved by driving the moving stage, the process of the region AR6 is performed.

In the process of region 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 as well, a part of the coating film 350 may still be located in the region AR4.

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

As shown in the state (d) and the state (e) of FIG. 12, when the diffused light E is irradiated on the coating film 350, further phase separation starts from the intermediate position of the coating film 350 and the columnar region 323. Begins to form and gradually grows. 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 step of the region AR6, the matrix region 321 is also formed along with the formation of the columnar regions 313 and 323, and the columnar regions 313 and 323 and the matrix region 321 reach the lower surface. As described above, the region from the intermediate position to the lower surface forms a hybrid structure in which two types of structures, a pillar structure formed by the columnar region 313 and a louver structure formed by the columnar region 323, coexist. Due to the formation of 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 diffusing element 340 and the coating film 350, the type of the directional diffusing element 340, and the like. The size of the columnar region becomes smaller as the distance is shortened, and the size of the columnar region becomes larger as the distance is lengthened. 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 in a form substantially corresponding to the aspect ratio. As the aspect ratio becomes smaller, the diffusion range may become narrower. Therefore, in this embodiment, the aspect ratio is set to 2 or more. The aspect ratio is more preferably 2 or more and less than 50, further 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 diffusing property and the light collecting property are improved.

As described above, when the coating film 350 undergoes the steps of the region AR5 and the region AR6, 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 this embodiment, a method using a moving stage is adopted for continuously forming the anisotropic light diffusion layers 310 and 320, but the method is not limited to this, and FIGS. 12 (a) to 12 (a) to ( The upper layer of the coating film is cured by a method such as c) (up to the process of region AR5) as one step and FIGS. 12 (d) to (e) as another step (after the step of region AR6). An anisotropic light diffusing layer 320 may be formed by forming a directional light diffusing layer 310, and then changing the light irradiation conditions in a state where an uncured layer exists as a lower layer of the coating film, or the like. , The anisotropic optical film 300 according to this embodiment can be formed.

In the present anisotropic light diffusion layer forming step, the total irradiation time of light 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 the present embodiment are obtained by forming a specific internal structure in the photocurable composition layer by irradiating the light with low illuminance for a relatively long time as described above. is there. Therefore, the unreacted monomer component may remain only by such light irradiation, causing stickiness, and there may be a problem in handleability and durability. In such a case, the residual monomer can be polymerized by additionally irradiating light with 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 where the masks are laminated), which is the surface opposite to the first irradiation for forming the anisotropic light diffusion layer of the coating film 350. May be good.

<<< Applications 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. Display devices that can preferably use the anisotropic optical film include, for example, a liquid crystal display (LCD), a plasma display panel (PDP), an organic EL display, a field emission display (FED), a rear projector, and a cathode ray tube display device. (CRT), surface electric field display (SED), electronic paper and the like. Particularly preferably, it is used for LCD.

Further, for example, when the anisotropic optical film according to the present embodiment is used for the LCD, the anisotropic optical film may be arranged on the emission 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, the liquid crystal display is formed on the polarizing plate or on glass. An anisotropic optical film according to this embodiment can be arranged between the substrate and the polarizing plate. As the transparent glass substrate, nematic liquid crystal, polarizing plate and the like, generally known ones can be used.

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these examples.

[Manufacturing 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 wall having a height of 0.045 mm was formed of a curable resin using a dispenser around the entire edge of a PET film having a thickness of 100 μm (manufactured by Toyobo Co., Ltd., trade name: A4300). The following photocurable resin composition was filled therein and covered with a PET film.
-Silicone urethane acrylate (refractive index: 1.460, weight average molecular weight: 5,890) 20 parts by weight (manufactured by RAHN, trade name: 00-225 / TM18)
-Neopentyl glycol diacrylate (refractive index: 1.450) 30 parts by weight (manufactured by Daicel Cytec, trade name Ebecryl 145)
EO adduct diacrylate of bisphenol A (refractive index: 1.536) 15 parts by weight (manufactured by Daicel Cytec, trade name: Ebecil150)
・ 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: Irgacure651)

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

Further, the parallel light rays emitted from the epi-illumination unit of the UV spot light source from the upper part are continuously irradiated ^{for 20 seconds with an irradiation intensity of 5 mW / cm 2} perpendicularly from the normal direction of the coating film surface to form a columnar structure. An anisotropic light diffusion layer having a large number of plate-like structures was formed under 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 off the PET film. Further, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Example 2)
A directional diffuser that irradiates light converted into linear rays via a directional diffuser for 10 seconds, irradiates parallel rays for 30 seconds, and has an aspect ratio of transmitted UV rays of 3 and a minor axis of 3 μm. An anisotropic optical film of Example 2 was obtained in the same manner as in Example 1 except that it 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 off the PET film. Further, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Example 3)
Light converted into linear light rays via a directional diffuser was irradiated for 30 seconds, parallel rays were irradiated for 10 seconds, and the anisotropy of transmitted UV rays with an aspect ratio of 3 and a minor axis of 1.3 μm. An anisotropic optical film of Example 3 was obtained in the same manner as in Example 1 except that the diffuser 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 off the PET film. Further, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

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

The liquid film sandwiched between the PET films on both sides is heated, and the parallel light rays emitted from the epi-illumination irradiation unit of the UV spot light source from above are perpendicular to the normal direction of the coating film surface, and the irradiation intensity is 5 mW / cm ^2. An anisotropic light diffusing layer having a large number of columnar structures was formed on the upper layer of the liquid film by irradiating the film for 10 seconds.

Furthermore, the parallel UV rays emitted from the epi-illumination unit of the UV spot light source (manufactured by Hamamatsu Photonics, trade name: L2859-01) are continuously transmitted from above with an aspect ratio of 3 and a minor axis of 3 μm. Ultraviolet rays converted into linear light rays are vertically irradiated through a directional diffusing element with an irradiation intensity of 5 mW / cm ² for 30 seconds to form an anisotropic light diffusing layer having many columnar structures and plate-like structures. It was formed in the lower layer 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 off the PET film. Further, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film. Further, FIG. 14 shows cross-sectional photographs of the anisotropic optical film according to this example in the MD direction and the TD direction.

(Example 5)
A directional diffusing element that irradiates parallel rays for 30 seconds, irradiates light converted into linear rays via a directional diffusing element for 10 seconds, and has an aspect ratio of transmitted UV rays of 3 and a minor axis of 1.3 μm. An anisotropic optical film of Example 5 new was obtained in the same manner as in Example 4 new except that it 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 off the PET film. Further, 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 element was changed to a directional diffuser having an aspect ratio of 8 transmitted UV rays 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 off the PET film. Further, 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 diffuser had an aspect ratio of 45 for the transmitted UV light 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 off the PET film. Further, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Example 8)
Changed to irradiating parallel rays for 20 seconds, irradiating light converted into linear rays via a directional diffusing element for 20 seconds, and changing to a directional diffusing element with an aspect ratio of 8 transmitted UV rays and a minor axis of 2 μm. An anisotropic optical film of Example 8 was obtained in the same manner as in Example 4 except for the above. 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 off the PET film. Further, 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 irradiation intensity of ultraviolet rays ^{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. Further, 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 the parallel light rays were 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 off the PET film. Further, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film. Further, FIG. 15 shows cross-sectional photographs of the anisotropic optical film according to this example in the MD direction and the TD direction.

(Example 11)
The same as in Example 1 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. 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 off the PET film. Further, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Example 12)
Same as Example 4 new except that the parallel rays were irradiated at an angle of 10 ° from the normal direction of the coating film surface and the transmitted UV rays were changed to a directional diffuser having an aspect ratio of 3 and a minor axis of 2 μm. 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 off the PET film. Further, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Comparative Example 1)
Anisotropy of Comparative Example 1 in the same manner as in Example 1 except that the ultraviolet rays converted into linear rays through the directional diffusion element of Example 1 were irradiated for 40 seconds and the parallel rays were irradiated 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. The results of measuring the anisotropic light diffusion layer and the structure of the columnar structure after peeling off the PET film are shown in Tables 1 and 2. Further, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

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

(Comparative Example 3)
Change to a directional diffuser with an aspect ratio of 45 transmitted UV rays and a minor axis of 2 μm, irradiate ultraviolet rays converted into linear rays via the directional diffuser for 40 seconds, and irradiate parallel rays for 0 seconds. An anisotropic optical film of Comparative Example 3 was obtained in the same manner as in Example 1 except for the above. That is, in this comparative example, an anisotropic optical film having only the first columnar structure was obtained. The results of measuring the anisotropic light diffusion layer and the structure of the columnar structure after peeling off the PET film are shown in Tables 1 and 2. Further, Table 3 shows the results of evaluating the optical characteristics of the anisotropic optical film.

(Comparative Example 4)
The partition wall of Example 1 is set to 0.025 mm, and only ultraviolet rays converted into linear rays via a directional diffusion element are irradiated for 20 seconds perpendicularly from the normal direction of the coating film surface to diffuse the anisotropic light of the first layer. A layer was formed. After obtaining the anisotropic light diffusing layer of the first layer, the PET film of the cover was peeled off, and then a 0.020 mm partition wall was further formed on the partition wall formed in the first layer. A similar photocurable resin composition was filled on the square light diffusing layer and covered with a PET film. Then, parallel light rays were irradiated perpendicularly from the normal direction of the coating film surface for 20 seconds to obtain a second anisotropic light diffusing layer, which was used as the anisotropic optical film of Comparative Example 4. The results of measuring the anisotropic light diffusion layer and the structure of the columnar structure after peeling off the PET film are shown in Tables 1 and 2. Further, 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. The results of measuring the anisotropic light diffusion layer and the structure of the columnar structure after peeling off the PET film are shown in Tables 1 and 2. Further, 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 of a curable resin in the same manner as in Example 1, and a photocurable resin composition similar to that in Example 1 was filled therein.
Similar to Example 1, this liquid film is heated to transmit parallel UV rays emitted from the epi-illumination unit of the UV spot light source from above. Directionality of the transmitted UV rays having an aspect ratio of 45 and a minor axis of 2 μm. Ultraviolet rays converted into linear light rays via a diffusing element were vertically irradiated ^{for 20 seconds with an irradiation intensity of 5 mW / cm 2} , and an anisotropic light diffusing layer having many plate-like structures was formed in the lower layer of the liquid film.
Further, the liquid film is covered with a PET film, and parallel light rays emitted from the epi-illumination unit of the UV spot light source are irradiated vertically from the normal direction of the coating film surface for 20 seconds ^{with an irradiation intensity of 5 mW / cm 2.} An anisotropic light diffusing 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. The results of measuring the anisotropic light diffusion layer and the structure of the columnar structure after peeling off the PET film are shown in Tables 1 and 2. Further, 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 and acrylate)
The weight average molecular weight (Mw) of the silicone urethane acrylate used as the photopolymerizable compound was measured by using the GPC method as the polystyrene-equivalent molecular weight under the following conditions.
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 (manufactured 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 diffusing layer of the anisotropic optical films of Examples and Comparative Examples was measured by observing and measuring the cross section of the anisotropic optical film formed by using a microtome with an optical microscope.

<< Surface observation of anisotropic optical film >>
The surface of the anisotropic optical film of Examples and Comparative Examples (opposite side of the irradiation light at the time of ultraviolet irradiation) is observed with an optical microscope, and the major axis LA and minor axis SA of any 100 first columnar structures and optional The major axis LA and minor axis SA of the 100 second columnar structures of No. 1 were measured, and the average value of each was calculated (see Table 1). Further, the aspect ratio (average major axis / average minor axis) was calculated based on the calculated average major axis and average minor axis.

<< Linear transmittance >>
Anisotropic optical films of Examples and Comparative Examples using a goniometer (manufactured by Genesia), a variable-angle photometer that can arbitrarily change the projection angle of the light source and the light-receiving angle of the detector, as shown in FIG. The optical characteristics of the above were evaluated. The detector was fixed at a position where it received straight light from a light source, and the anisotropic optical film obtained in Examples and Comparative Examples was set in a sample holder in between. As shown in FIG. 2, the sample was rotated about 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 what 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 amount of linearly transmitted light was measured by measuring the wavelength in the visible light region using a luminous efficiency filter. Based on the optical profile obtained as a result of the above measurements, the maximum value (maximum linear transmittance) and the minimum value (minimum linear transmittance) of the linear transmittance were determined.

<< MD direction diffusion and TD direction diffusion >>
Using a device as shown in FIG. 2, the anisotropic optical films of Examples and Comparative Examples are irradiated with straight light from a fixed light source, and the transmitted light is moved (rotated) in the MD direction and the TD direction of the sample. Was received by the detector to measure the transmittance. Optical profiles were created based on the above-mentioned 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, the range of the incident light angle, which is an intermediate value between the maximum linear transmittance and the minimum linear transmittance, is obtained from each optical profile when moved in the MD direction and the TD direction, and this range is set to the MD direction diffusion and the TD, respectively. The width of directional diffusion (°) was used.

<< Rapid change in brightness >>
In the measurement of the above-mentioned linear transmittance, as shown in FIG. 16, an angle B to take angles taking the maximum line transmittance _{F A (%) A (°} ) and the minimum linear transmittance F _{B (%) (°)} If the linear transmittance changes abruptly, the brightness also changes abruptly. Therefore, the inclination of the linear transmittance is obtained, and if the inclination is steep, there is a sudden change in brightness, and the inclination. If is gentle, it is judged that there is no sudden change in brightness. Specifically, the slope alpha of the linear transmittance _{(F A -F B) / |} A-B | and then, and this inclination alpha is, if alpha ≧ 1.7, there is a sudden change in luminance , 1.5 ≤ α <1.7, the change was rather abrupt but within the permissible range, and when α <1.5, the change in brightness was gradual and there was no discomfort. As shown in FIG. 17, among the following (a) and (b), the _{maximum linear transmittance (FA1} and _FA2 ) and the minimum linear transmittance ( _FB1 and _FB2 ), which are two types, respectively, are the values. Gayori larger ones were with _{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 (a) and (b) above was used as the slope α from the maximum linear transmittance to the minimum linear transmittance in the optical profile.

<< Glitter >>
A light reflecting layer was provided under the anisotropic optical film of Examples and Comparative Examples, and light was incident from above the light reflecting layer, and the glare of the reflected light was visually confirmed.

<< Productivity >>
Productivity is defined as high productivity in the process of manufacturing anisotropic optical films, which can be continuously (1 pass) coated and UV-irradiated without interrupting the production, and other than that. In this case, it was judged that the productivity was low.

<<< Evaluation Criteria >>>
The evaluation criteria for the 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 direction diffusion width”
◎ 40 ° or more ○ 30 ° or more and less than 40 ° △ 20 ° or more and less than 30 ° × less than 20 ° “TD direction diffusion width”
◎ 20 ° or more ○ 10 ° or more and less than 20 ° △ 5 ° or more and less than 10 ° × less than 5 ° “Abrupt change in brightness”
◎ The change in brightness is gradual, and there is no sense of discomfort △ The change is a little sudden, but the allowable range × There is a sudden change in brightness "Glitter"
◎ No glare △ There is some glare but acceptable range × “Productivity” with clear glare
◎ Can be manufactured by 1-pass coating / UV irradiation, high productivity × 2 or more passes of coating / UV irradiation required, low productivity

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

More specifically, as shown in Table 3, the anisotropic optical film of the example has a high maximum linear transmittance, a wide diffusion width in the MD direction and the TD direction, and also has abrupt changes in brightness and glare. There was no such thing, and the productivity was excellent, and all the evaluation items had a high level of characteristics in a well-balanced manner. In particular, in Example 1, Example 8 and Example 10, since there is no evaluation of Δ, it can be said that the anisotropic optical film is particularly excellent. On the other hand, some of the anisotropic optical films of the comparative examples had a better evaluation than the examples in specific items, but the maximum linear transmittance, diffusion in the TD direction, abrupt changes in brightness, glare, and the like. At least one or more items of productivity had a very bad result of ×, and none of the evaluation items had a high level of characteristics in a well-balanced manner as in the examples. ..

Therefore, the anisotropic optical film of the example can achieve both a high linear transmittance in the non-diffusion region and a wide diffusion region in the MD direction and the TD direction, and the anisotropic optical film can be diffused in the display panel. When used as a film, it can suppress sudden changes in brightness and the occurrence of glare while having excellent display characteristics (brightness, contrast, etc.). That is, according to the anisotropic optical film of the present embodiment, it is possible to compensate for the defects of the pillar structure and the louver structure, and the transmittance in the non-diffusion region is improved as compared with the pillar structure and the MD direction. The diffusion angle range of the louver structure is expanded, and the diffusion angle range in the TD direction is also expanded as compared with the louver structure, and a sudden change in brightness and glare can be eliminated. In addition, the defects of both structures can be compensated for without laminating the layers, so that the productivity is also excellent.

Although preferred embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the above-described embodiments. 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 also belong to the technical scope of the present invention.

100, 200, 300 Anisotropic optical film 110, 210, 310 (having a single columnar region) Anisotropic light diffusing layer 111, 211, 311 Matrix region 113, 213, 313 Columnar region 119 Top 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 diffusing element 330 Shading plate 250, 350 Coating film SA Short diameter LA Major diameter

Claims (9)

An anisotropic optical film having at least an anisotropic light diffusing layer whose linear transmittance changes depending on the angle of incident light.
The anisotropic light diffusion layer is
A first anisotropic light diffusing layer having a matrix region and a plurality of first columnar structures and having a first surface and an intermediate surface,
A second anisotropic light diffusion layer continuous with the first anisotropic light diffusion layer on the intermediate surface, which has a matrix region, a plurality of second columnar structures, and a plurality of first columnar structures, and is a second. With a second anisotropic light diffusing layer having a surface of
The intermediate surface is a position where the layer thickness of the first anisotropic light diffusing layer and the second anisotropic light diffusing layer exceeds 20% from the first surface.
The first columnar structure is configured and oriented toward the second surface of the first said from the first surface of the anisotropic light-diffusing layer of the second anisotropic light-diffusing layer,
The second columnar structure is formed so as to be oriented from the intermediate surface to the second surface.
The first columnar structure becomes discontinuous on the first surface and the second surface.
The anisotropic optical film, characterized in that the second columnar structure is discontinuous on the second surface. The aspect ratio of the average minor axis to the average major axis in one of the first columnar structure and the second columnar structure is 2 or more.
The anisotropic optical film according to claim 1, wherein the aspect ratio of the average minor axis to the average major axis of the first columnar structure and the other of the second columnar structure is less than 2. .. The average minor axis and the average major axis of 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.
Claimed that the average minor axis and the average major axis of the first columnar structure and the other of 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 any one of claims 1 to 3, wherein the anisotropic light diffusion layer has a thickness of 10 μm to 200 μm. Maximum linear transmittance, and less than 80% 30%, anisotropic optical film according to any one of claims 1 to 4. Claims 1 to 5, wherein 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 according to any one of the above items. The anisotropic optics according to any one of claims 1 to 6, wherein the diffusion width in the MD direction is 30 ° or more and less than 70 °, and the diffusion width in the TD direction is 10 ° or more and less than 30 °. the film. A coating process in which a composition for forming an anisotropic light diffusing layer is applied onto a base material to provide a coating film, and
A first structure forming step in which a mask film is laminated on the coating film and then cured by irradiation with light rays from above.
After the first structure forming step, a second structure forming step of continuously curing by irradiation with light rays is included.
Of the first structure forming step and the second structure forming step, one step is cured by irradiation with one-way diffused light rays, and the other step is cured by irradiation with parallel rays. The method for producing an anisotropic optical film according to any one of claims 1 to 7. The one-way diffused ray in the first structure forming step or the second structure forming step is a diffused ray obtained through a directional diffusing element, and the aspect ratio of the diffused ray is 2 or more. The production method according to claim 8, which is characterized.

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