JP2015222441A - Anisotropic optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic optical film that can perform diffusion and condensation of light in a wide incident angle range even when the film has a single layer of an anisotropic diffusion layer and that does not give an observer an unnatural impression.SOLUTION: The anisotropic optical film includes at least a low refractive index region and a high refractive index region in a single layer of an anisotropic diffusion layer: on a surface (X-Y plane) of the single layer of the anisotropic diffusion layer, the low refractive index region and the high refractive index region are alternately arranged; and in a cross-section of the single layer of the anisotropic diffusion layer, the low refractive index region and the high refractive index region have a bent structure in a thickness direction (Z direction). The bent structure is obtained since a gradient of a first diffusion center axis is different from a gradient of a second diffusion center axis; and a plurality of bending angles obtained by the gradient of the first diffusion center axis and the gradient of the second diffusion center axis is present in the X direction.

Description

   The present invention relates to an anisotropic optical film having a wide diffusion range and light collecting properties.

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

  On the other hand, a light control plate (anisotropic optical film) is known in which incident light in a certain angle region is strongly diffused and incident light at other angles is transmitted (for example, Patent Document 1). This light control plate is cured by irradiating light from above the sheet-like photosensitive composition layer using a linear light source. And in the sheet-like substrate, as shown in FIG. 14, the peripheral region and the refractive index coincide with the length direction of the linear light source 51 disposed above the anisotropic optical film 50 when the anisotropic optical film 50 is produced. It is considered that different plate-like structures 40 are formed in parallel to each other. As shown in FIG. 15, a sample 1 (anisotropic optical film) is arranged between a light source (not shown) and a light receiver 3, and the sample is transmitted straight through while changing the angle with the straight line L of the sample surface as the central axis. Thus, the linear transmittance entering the light receiver 3 can be measured.

  FIG. 12 shows the incident angle dependence of the scattering characteristics of the anisotropic optical film 50 shown in FIG. 14 measured using the method shown in FIG. FIG. 12 evaluates an anisotropic optical film of Comparative Example 1 described later. The vertical axis indicates the linear transmittance (an amount of parallel light emitted in the same direction as the incident direction when a predetermined amount of parallel light is incident), which is an index indicating the degree of scattering, and the horizontal axis indicates the incident angle. Indicates. The solid and broken lines in FIG. 12 rotate the anisotropic optical film 50 around the AA axis (through the plate structure) and the BB axis (parallel to the plate structure) in FIG. 14, respectively. Show the case. The sign of the incident angle indicates that the direction in which the anisotropic optical film 50 is rotated is opposite. The solid line in FIG. 12 shows that the linear transmittance remains small both in the front direction and in the oblique direction. This is because the optical film 50 is scattered regardless of the incident angle when rotated about the AA axis. It means a state. In addition, the broken line in FIG. 12 shows that the linear transmittance is small in the direction near 0 °. This is because the optical film is directed to the light in the front direction even when rotated about the BB axis. Means that it is in a scattering state. Furthermore, the linear transmittance increases in the direction where the incident angle is large. This is because when the anisotropic optical film is rotated around the BB axis, the anisotropic optical film is in a state of transmitting light in an oblique direction. It means that. Thanks to this structure, for example, although the transmissivity varies depending on the incident angle in the horizontal direction, the transmissivity does not change even if the incident angle is changed in the vertical direction. Here, the curve indicating the incident angle dependence of the scattering characteristic as shown in FIG. 12 is hereinafter referred to as an “optical profile”. The optical profile does not directly represent the scattering characteristics, but if it is interpreted that the diffuse transmittance is increased due to the decrease of the linear transmittance, the diffusion profile is generally indicated. I can say that.

  The optical characteristics of the anisotropic optical film 50 are defined by the inclination of the plate-like structure 40 with respect to the film normal. In this case, the incident light from a direction substantially parallel to the plate-like structure 40 is strongly diffused, and the incident light passing through the plate-like structure is transmitted without being diffused. It can be said.

  Since the properties of the anisotropic optical film 50 depend on the inclination of the plate-like structure and the inclination of incident light, the incident angle range when light is strongly diffused is limited. In addition, since the anisotropic optical film 50 has a very steep change in diffusivity when the incident angle is changed, when it is applied to a display device, it appears as a sudden change in visibility, giving an unnatural impression. There was something to hold me. In order to solve this problem, there is a method of laminating a plurality of anisotropic optical films in which the inclination of the plate-like structure is changed.

Japanese Patent No. 2547417

  In the present invention, even if it is a single anisotropic diffusion layer, anisotropy that can diffuse and collect light over a wide range of incident angles and does not give an unnatural impression. An object is to provide an optical film.

The present invention has solved the above problems by the following technical configuration.

(1) It has at least a low refractive index region and a high refractive index region in one anisotropic diffusion layer, and the low refractive index is on the surface (XY plane) of the one anisotropic diffusion layer. The regions and the high refractive index regions are alternately arranged, and the low refractive index region and the high refractive index region are bent in the thickness direction (Z direction) in the cross section of the one anisotropic diffusion layer. And the bent structure is obtained from the difference between the inclination of the first diffusion center axis and the inclination of the second diffusion center axis, and the inclination of the first diffusion center axis and the second diffusion center axis. An anisotropic optical film characterized in that a plurality of bending angles obtained from the inclination of the central axis exist in the X direction.
(2) The bent structure is obtained from the difference between the inclination of the first diffusion center axis and the inclination of the second diffusion center axis, and the inclination of the first diffusion center axis and the second diffusion center axis. The anisotropic optical film as described in (1) above, wherein a plurality of bending angles having different angles obtained from the inclination are present in the X direction.
(3) The anisotropic optical film according to (1) or (2), wherein a plurality of bending angles in the X direction are gradually increased.
(4) It has a configuration in which the interface between the low refractive index region and the high refractive index region is continuously present without interruption over the thickness direction of the one layer of anisotropic diffusion layer. The anisotropic optical film according to any one of (1) to (3).
(5) The bending direction of the low refractive index region and the high refractive index region gradually changes without interruption over the thickness direction of the one anisotropic diffusion layer (1) The anisotropic optical film according to any one of (1) to (4).
(6) The maximum linear transmittance at an incident angle at which the linear transmittance of the one anisotropic diffusion layer is maximum is 50% or more, and the linear transmittance of the one anisotropic diffusion layer is minimum. The angle range of the diffusion range of incident light with respect to the linear transmittance at which the minimum linear transmittance at an incident angle is 20% or less and the difference between the maximum linear transmittance and the minimum linear transmittance is ½ or less The anisotropic optical film as described in any one of (1) to (5) above, wherein the angle is 40 ° to 80 °.
(7) The absolute value of the bending angle between the first diffusion center axis and the second diffusion center axis is 10 to 40 °, and any one of (1) to (6) above An anisotropic optical film described in 1.
(8) The inclination of at least one diffusion center axis of the first diffusion center axis and the second diffusion center axis is in a range of ± 5 °, and the inclination of another diffusion center axis is −15 ° to The anisotropic optical film according to any one of (1) to (7), which is in a range of −5 ° or + 5 ° to + 15 °.

  In the present invention, even if it is a single anisotropic diffusion layer, anisotropy that can diffuse and collect light over a wide range of incident angles and does not give an unnatural impression. An optical film can be provided.

It is a schematic diagram of the anisotropic optical film of this invention, Comprising: (a) A perspective view, (b) Cross-sectional view. It is sectional drawing of another anisotropic optical film of this invention. It is sectional drawing of another anisotropic optical film of this invention. It is sectional drawing of another anisotropic optical film of this invention. 1 is a cross-sectional view of an anisotropic optical film of Example 1. FIG. 3 is a cross-sectional view of an anisotropic optical film of Example 2. FIG. 6 is a cross-sectional view of an anisotropic optical film of Example 3. FIG. 2 is a cross-sectional view of an anisotropic optical film of Comparative Example 1. FIG. It is a figure which shows the linear transmittance | permeability of the anisotropic optical film of Example 1. It is a figure which shows the linear transmittance | permeability of the anisotropic optical film of Example 2. It is a figure which shows the linear transmittance | permeability of the anisotropic optical film of Example 3. It is a figure which shows the linear transmittance | permeability of the anisotropic optical film of the comparative example 1. It is a figure explaining the positive / negative of a bending angle, Comprising: (a) When a bending angle becomes positive, (b) When a bending angle becomes negative. It is a schematic diagram of the conventional anisotropic optical film. The measuring method of the optical profile of an anisotropic optical film is shown.

  Here, the definitions of each term in the claims and the specification will be described.

  The “low refractive index region” and the “high refractive index region” are regions formed by a difference in local refractive index of the material constituting the anisotropic optical film and have a lower refractive index than the other. It is a relative one indicating whether it is expensive. These regions are formed when the material forming the anisotropic optical film is cured.

  The “diffusion center axis” means a direction in which the scattering characteristic coincides with the incident angle of light having substantially target property with the incident angle as a boundary when the incident angle is changed. The reason for having “substantially target” is because it does not strictly have the target of optical characteristics. The diffusion center axis can be found by observing the inclination of the film cross section with an optical microscope or by observing the projection shape of light through the anisotropic optical film while changing the incident angle.

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

  The anisotropic diffusion layer has a plurality of diffusion center axes in the thickness direction. That is, it has a first diffusion center axis in the upper part of one anisotropic diffusion layer and a second diffusion center axis in the middle part of the anisotropic diffusion layer. Further, a third diffusion center axis may be provided under the one anisotropic diffusion layer. The “upper part”, “middle part”, and “lower part” of the anisotropic diffusion layer indicate the relative positional relationship of the diffusion center axis. There may be an upper part and a middle part, and the lower part may not be present. Matters other than the relative positional relationship of the diffusion center axis can be set as appropriate. Between one interface of the anisotropic diffusion layer and the top of the anisotropic diffusion layer, between the top and middle of the anisotropic diffusion layer, between the middle and bottom of the anisotropic diffusion layer, Another phase may be contained between the lower interface and the other interface of the anisotropic diffusion layer.

  In the present invention, “scattering” and “diffusion” are used without distinction, and both indicate the same meaning.

The contents of the present invention will be described below.
FIG. 1 is a schematic view of an anisotropic optical film 5 of the present invention. FIG. 1A is a perspective view of the anisotropic optical film 5, and FIG. 1B is a cross-sectional view of the anisotropic optical film 5 cut along the line AA in FIG.
As shown in FIG. 1, the anisotropic optical film 5 is formed such that the low refractive index regions 4 and the high refractive index regions 6 are alternately arranged on the surface and cross section of the anisotropic optical film 5. The low refractive index region 4 and the high refractive index region 6 are formed to be bent in the thickness direction (Z direction) of the anisotropic optical film 5, and the low refractive index region 4 and the high refractive index region 6 are formed on the film surface. Are lined up alternately. That is, the anisotropic optical film 5 of the present invention forms a structure in which the low refractive index region 4 and the high refractive index region 6 on the film surface are bent and extended in the thickness direction. In addition to the low refractive region 4 and the high refractive region 6, other refractive index regions may be included. As another refractive index area | region, a middle refractive index area | region is mentioned, for example. In FIG. 1, a lower portion or the like may be provided below the middle portion 72 of the anisotropic diffusion layer 7.

  In FIG. 1B, the upper surface 5a and the lower surface 5b of the anisotropic diffusion layer 7 are illustrated. The upper surface 5a and the lower surface 5b are provided for the sake of convenience. If the anisotropic diffusion layer 5 is turned upside down, they are reversed (lower surface and upper surface). In the present invention, the structure in which the interface between the low refractive index region 4 and the high refractive index region 6 is continuously present without being interrupted in the thickness direction (Z direction) of the single anisotropic diffusion layer 7. It is preferable to have. By having a configuration in which the interface between the low refractive index region 4 and the high refractive index region 6 is connected, light diffusion and light collection easily occur continuously while passing through the anisotropic diffusion layer 7, and light diffusion And the efficiency of light collection increases. On the other hand, when the low refractive index region and the high refractive index region are mainly mottled like spots in the cross section of the anisotropic diffusion layer 7, it is difficult to obtain the light condensing property which is the effect of the present invention. Therefore, it is not preferable.

The maximum linear transmittance at an incident angle at which the linear transmittance of the anisotropic diffusion layer is maximized is preferably 50% or more. The reason why the incident angle at which the linear transmittance is maximized is that the linear transmittance varies depending on the incident angle. The upper limit value of the maximum linear transmittance is not limited, but is 95%, for example.
The minimum linear transmittance at an incident angle at which the linear transmittance of the anisotropic diffusion layer is minimum is preferably 20% or less. It shows that the amount of linear transmitted light decreases as the minimum linear transmittance decreases. Therefore, the amount of diffused light increases as the minimum linear transmittance decreases. A lower minimum transmittance is preferred. It is preferably 10% or less, and more preferably 5% or less. Although a lower limit is not limited, For example, it is 0%.
Here, the linear transmitted light amount and the linear transmittance can be measured by the method shown in FIG. That is, the linear transmitted light amount and the linear transmittance are measured at each incident angle so that the rotation axis L shown in FIG. 15 and the BB axis shown in FIG. And). An optical profile is obtained from the obtained data, and the maximum linear transmittance and the minimum transmittance are obtained from this optical profile.

From the above, the maximum linear transmittance and the minimum linear transmittance of the anisotropic diffusion layer are obtained, and the difference between the maximum linear transmittance and the minimum linear transmittance is obtained. A straight line that is ½ of the difference is created in the optical profile, two intersections where the straight line and the optical profile intersect are obtained, and an incident angle corresponding to the intersection is read. Here, in the optical profile, the normal direction is set to zero degrees, and the incident angle is shown in the minus direction and the plus direction. Therefore, the incident angle corresponding to the incident angle and the intersection may have a negative value. If the value of the two intersections has a positive incident angle value and a negative incident angle value, the sum of the absolute value of the negative incident angle value and the positive incident angle value is the angular range of the incident light diffusion range. It becomes.
When the values of the two intersection points are both positive, the difference obtained by subtracting the smaller value from the larger value is the angular range of the diffusion range of the incident light. 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 angular range of the incident light diffusion range.

  It is preferable that the angle range of the diffusion range of incident light with respect to the linear transmittance where the difference between the maximum linear transmittance and the minimum linear transmittance is ½ or less is 40 ° to 80 °. If the angle range of the incident light diffusion range is smaller than 40 °, it is not much different from the conventional anisotropic optical film. A more preferable angle range of the diffusion range is 50 to 80 °, and an angle range of 50 ° or more is an angle range that cannot be achieved unless an internal structure having a large bend is obtained. As an internal structure having a large bend, the inclination of the diffusion center axis described later is 10 ° or more. On the other hand, if the angle range of the diffusion range of incident light exceeds 80 °, the light collecting property is impaired, which is not preferable.

The anisotropic optical film 5 of the present invention has a substantially plate-like structure bent in the thickness direction. That is, the low refractive index region 4 has a substantially square shape in the in-plane direction (XY plane) of the anisotropic optical film, but in the thickness direction (Z direction) of the anisotropic diffusion layer 7. It has a bending structure. Since the low refractive index regions 4 and the high refractive index regions 6 are alternately formed, if the low refractive index regions 4 are bent, the high refractive index regions 6 are also bent.
In this specification, the low refractive index region 4 is mainly described as being bent. However, the low refractive index region 4 may be replaced with a high refractive index region. In any embodiment, the effect of the present invention can be obtained.

The structure of the low refractive index region 4 will be described in detail with reference to FIGS. The low refractive index region 4 includes at least a low refractive index region 41 having a _first diffusion center axis R ₁ at the upper portion 71 of the anisotropic diffusion layer 7 and a second diffusion center at the middle portion 72 of the anisotropic diffusion layer 7. having a low refractive index region 42, having an axis _{R 2.} First diffusion center axis R ₁ and the second diffusion center axis R ₂ are those having different slopes, respectively. The inclination of the diffusion center axis can be expressed using the direction of the normal S as a reference (0 °). That is, since the first diffusion center axis R ₁ is inclined by θ ₁ ° from the normal line S, the first diffusion center axis R ₁ is inclined by θ ₁ °. Similarly, since the second diffusion center axis R ₂ is inclined by θ ₂ ° from the normal line S, the second diffusion center axis R ₂ is inclined by θ ₂ °. Here, since the first diffusion center axis R ₁ and the second diffusion center axis R ₂ are inclined in the minus direction and the plus direction with respect to the normal line S, θ ₁ ° and θ ₂ ° sum, the bending angle of the first diffusion center axis R ₁ and the second diffusion center axis R _2. The above can be applied even when one inclination of the diffusion center axis becomes zero.
Note that the low refractive index region 41 and the low refractive index region 42 have different signs to show different inclinations, but these refractive indexes are substantially the same.

FIG. 2 is a cross-sectional view of another anisotropic optical film 51. Similar to FIG. 1, FIG. 2 also shows the low diffusion region 410 having the first diffusion center axis R ₁₀ in the upper part 71 of the anisotropic diffusion layer 7 and the second diffusion in the middle part 72 of the anisotropic diffusion layer 7. having a low refractive index region 420, having a central axis _{R 20.} In FIG. 2, the first diffusion center axis R ₁₀ and the second diffusion center axis R ₂₀ are inclined in the same direction (both positive directions) with respect to the normal S. In this case, a difference obtained by subtracting θ ₁₀ ° having a small inclination from θ ₂₀ ° having a large inclination is a bending angle between the first diffusion center axis R ₁₀ and the second diffusion center axis R ₂₀ .
Even when the diffusion center axis is in the negative direction with respect to the normal S, the difference obtained by subtracting the small inclination from the large inclination is the bending angle between the diffusion central axis and another diffusion central axis. become.

FIG. 3 is a cross-sectional view of another anisotropic optical film 52. FIG. 3A shows a case where the slopes of the low refractive index regions 411, 412, 413, and 414 gradually increase in the upper portion 71 of the anisotropic diffusion layer 7. Similarly, FIG. 3A shows a case where the slopes of the low refractive index regions 421, 422, 423, and 424 are gradually increasing in the lower portion 72 of the anisotropic diffusion layer 7. In this case, even in one anisotropic diffusion layer 7, there are a plurality of bending angles between the diffusion center axis and another diffusion center axis. There are also a plurality of first diffusion center axes and second diffusion center axes. In this case, the bending angle between the diffusion center axis and another diffusion center axis may be obtained for those in which the low refractive index regions are connected in the thickness direction of the anisotropic diffusion layer 7.
FIG. 3B shows a low refractive index region 411 having a first diffusion center axis R ₁₁ at the upper portion 71 of the anisotropic diffusion layer 7 and a second diffusion center axis at the middle portion 72 of the anisotropic diffusion layer 7. The low refractive index region 421 having R ₂₁ is shown. In this case, since the first diffusion center axis R ₁₁ and the second diffusion center axis R ₂₁ are inclined in the minus direction and the plus direction with respect to the normal line S, θ ₁₁ ° and θ ₂₁ ° sum, the bending angle of the first diffusion center axis R ₁₁ and the second diffusion center axis R _21. When the two diffusion center axes are inclined in the same direction with respect to the normal line S, a value obtained by subtracting a small inclination from a large inclination becomes a bending angle between the diffusion center axis and another diffusion center axis.
A low refractive index region 412 having a first diffusion center axis R ₁₂ in the upper portion 71 of the anisotropic diffusion layer 7 and a low refractive index region having a second diffusion center axis R ₂₂ in the middle portion 72 of the anisotropic diffusion layer 7. for 422, the low refractive index region 423 having the low refractive index region 413 having a first diffusion center axis _{R 13} of the second diffusion center axis _{R 23,} the low refractive index region having a first diffusion center axis _{R 14} Also for the low refractive index region 424 having 414 and the second diffusion center axis R ₂₄ , the bending angle between the diffusion center axis and another diffusion center axis can be obtained in the same manner as in FIG.

FIG. 4 is a cross-sectional view of another anisotropic optical film 53. FIG. 4 shows a low refractive index region 41 having a _first diffusion center axis R ₁ in the upper part 71 of the anisotropic diffusion layer 7 and a second diffusion center axis R ₂ in the middle part 72 of the anisotropic diffusion layer 7. And a low refractive index region 42 having a third diffusion center axis R ₃ at a lower portion 73 of the anisotropic diffusion layer 7. As shown in FIG. 4, the first diffusion center axis R _1, and the second diffusion center axis R _2, the third diffusion center axis R ₃ preferably has a different inclination, respectively. FIG. 4 shows a mode in which the third diffusion center axis R ₃ is newly added. In this case as well, the first diffusion center axis R ₁ and the third diffusion axis are similarly described above. The bending angle with the central axis R ₃ and the bending angle between the second diffusion central axis R ₂ and the third diffusion central axis R ₃ can be obtained.
Since the second diffusion center axis R ₂ coincides with the normal line S, the second diffusion center axis R ₂ is zero degrees. Since the third diffusion center axis R ₃ is inclined by θ ₃ ° from the normal line S, the third diffusion center axis R ₃ is inclined by θ ₃ °. Therefore, the sum of zero degrees and θ ₃ degrees becomes the bending angle between the _second diffusion center axis R ₂ and the third diffusion center axis R ₃ .
Since the first diffusion center axis R ₁ is inclined by θ ₁ ° from the normal line S, the first diffusion center axis R ₁ is inclined by θ ₁ °. Here, the first diffusion center axis R ₁ and the third diffusion center axis R ₃ are inclined in the same direction (both in the plus direction) with respect to the normal line S. In this case, a difference obtained by subtracting θ ₁ ° having a small inclination from θ ₃ ° having a large inclination becomes a bending angle between the first diffusion center axis R ₁ and the third diffusion center axis R ₃ .
Another phase (for example, the fourth diffusion center axis R ₄ ) may be provided below the lower portion 73 of the anisotropic diffusion layer 7 shown in FIG. 4 (on the opposite side of the middle portion 72).
Note that the low refractive index region 41, the low refractive index region 42, and the low refractive index region 43 have different signs to indicate different inclinations, but these refractive indexes are substantially the same.

The bending angle has a positive value or a negative value. FIG. 13 is a diagram for explaining the sign of the bending angle.
FIG. 13A shows a case where the bending angle is positive. FIG. 13A shows the configuration shown in FIG. 3B in another form. That is, the bending angle (θ ₁₁ + θ ₂₁ ) between the first diffusion center axis R ₁₁ and the second diffusion center axis R ₂₁ is shown. Here, since the extension of the first diffusion center axis R ₁₁ (shown in phantom) is located on the left side of the second diffusion center axis R _21, its bending angle will be a positive value.
FIG. 13B shows a case where the bending angle is negative. FIG.13 (b) shows what was shown in FIG.1 (b) in another form. That is, the bending angle (θ ₁ + θ ₂ ) between the _first diffusion center axis R ₁ and the second diffusion center axis R ₂ is shown. Here, since the extension line (indicated by the dotted line) of the _first diffusion center axis R ₁ is on the right side of the second diffusion center axis R ₂₁ , the bending angle thereof takes a negative value.

The bending angle has a positive value or a negative value, but is not particularly meaningful when there are two diffusion center axes. This is because there is only one value of the bending angle, and the bending angle will have the opposite sign if measured by switching the top and bottom of the anisotropic diffusion film.
On the other hand, when there are three or more diffusion center axes, there are a plurality of bending angles. For example, in the case of having a first diffusion center axis, a second diffusion center axis, and a third diffusion center axis, the bending angle is (1) the first diffusion center axis and the second diffusion center axis, (2) The first diffusion center axis and the third diffusion center axis, and (3) the second diffusion center axis and the third diffusion center axis are obtained. In this case, it is preferable to have a bending angle having a positive value and a bending angle having a negative value. Thereby, it is possible to further improve the light condensing property while maintaining the light intensity substantially constant.

Although depending on the material forming the anisotropic optical film, the angle at which one diffusion center axis strongly scatters light is such that the difference between the inclination of the diffusion center axis and the inclination of the light traveling direction is in the range of approximately ± 10 °. There is a time. Therefore, the absolute value of the bending angle between the first diffusion center axis and the second diffusion center axis is preferably 10 to 40 °. More preferably, efficient diffusion can be obtained at 15 to 25 °. As a result, a region where light is strongly scattered can be expanded. In addition, since the region that strongly scatters light can be formed continuously, the light condensing property can be enhanced while the light intensity is kept substantially constant.
The upper limit of the bending angle between the first diffusion center axis and the second diffusion center axis is not particularly limited. As shown in FIG. 1, when the first diffusion center axis and the second diffusion center axis are inclined in the plus direction and the minus direction with respect to the normal S, as shown in FIG. The upper limit value of the bending angle with the central axis is, for example, 140 °. When the first diffusion center axis and the second diffusion center axis are inclined in the same direction with respect to the normal S as shown in FIG. 2, the first diffusion center axis and the second diffusion center axis The upper limit value of the bending angle with the shaft is, for example, 70 °. Although it depends on the material forming the anisotropic optical film, light exceeding these upper limit values is likely to be reflected on the surface of the anisotropic optical film and is difficult to enter the anisotropic optical film.

  The absolute value of the bending angle between the first diffusion center axis and the third diffusion center axis is preferably 10 to 40 °. More preferably, efficient diffusion can be obtained at 15 to 25 °. As a result, the region where light is strongly scattered can be further expanded. In addition, since the region that strongly scatters light can be formed continuously, the light condensing property can be further enhanced in a state where the light intensity is kept substantially constant.

  The absolute value of the bending angle between the second diffusion center axis and the third diffusion center axis is preferably 10 to 40 °. More preferably, efficient diffusion can be obtained at 15 to 25 °. As a result, the region where light is strongly scattered can be further expanded. In addition, since the region that strongly scatters light can be formed continuously, the light condensing property can be further enhanced in a state where the light intensity is kept substantially constant.

  The absolute value of the bending angle between the first diffusion center axis and the second diffusion center axis and the absolute value of the bending angle between the first diffusion center axis and the third diffusion center axis are 10 to 40 °, respectively. Preferably there is. As a result, the region where light is strongly scattered can be further expanded. In addition, since the region that strongly scatters light can be continuously formed, the light condensing property can be further enhanced in a state where the light intensity is kept substantially constant.

  The inclinations of the first diffusion center axis, the second diffusion center axis, and the third diffusion center axis are preferably in the range of ± 70 ° when the normal direction is zero °. If it is smaller than −70 ° or larger than + 70 °, depending on the material forming the anisotropic optical film, light exceeding these upper limits tends to be reflected on the surface of the anisotropic optical film. This is because it is difficult to be incident on the conductive optical film.

  When the first diffusion center axis and the second diffusion center axis exist, the inclination of at least one of these axes is preferably in the range of ± 5 °, and another diffusion center axis Is preferably in the range of −15 ° to −5 ° or + 5 ° to + 15 °. As a result, the region where light is strongly scattered can be further expanded. In addition, since the region that strongly scatters light can be formed continuously, the light condensing property can be further enhanced in a state where the light intensity is kept substantially constant.

  When the first diffusion center axis, the second diffusion center axis, and the third diffusion center axis are present, the inclination of at least one of these axes is preferably in the range of ± 5 °. In addition, the inclination of the other diffusion center axis is preferably in the range of −15 ° to −5 ° or + 5 ° to + 15 °. The axes other than the two axes are preferably in the range of −25 ° to −15 ° or + 15 ° to + 25 °. As a result, the region where light is strongly scattered can be further expanded. In addition, since the region that strongly scatters light can be continuously formed, the light condensing property can be further enhanced in a state where the light intensity is kept substantially constant.

  The anisotropic optical film of the present invention has a structure in which the low refractive index region and the high refractive index region are bent and extended in the thickness direction in the cross section of the anisotropic diffusion layer. The bending direction may be such that the bent portion bends substantially linearly, gradually changes (for example, a curved shape), or changes sharply (for example, a linear shape). It may be. Thereby, the effect of the present invention can be obtained. In the present invention, it is preferable that the bending directions of the low refractive index region and the high refractive index region gradually change without interruption. By gradually changing without interruption, light can be efficiently diffused and collected.

An anisotropic optical film in which another layer is provided on one surface of the anisotropic diffusion layer may be used. Examples of other layers include an adhesive layer, a polarizing layer, a light diffusion layer, a low reflection layer, an antifouling layer, an antistatic layer, an ultraviolet / near infrared (NIR) absorption layer, a neon cut layer, and an electromagnetic wave shielding layer. be able to. Other layers may be sequentially stacked.
Other layers may be laminated on both surfaces of the anisotropic diffusion layer. 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 The anisotropic optical film of the present invention can be produced by subjecting a specific photocurable composition layer to UV irradiation under special conditions. Hereinafter, the raw material of the anisotropic optical film will be described first, and then the manufacturing process will be described.

Raw Material for Anisotropic Optical Film The material for forming the anisotropic optical film of the present invention is a photocurable compound selected from a macromonomer, polymer, oligomer or monomer having a radical polymerizable or cationic polymerizable functional group. It is a material composed of a photoinitiator and polymerized and solidified by irradiation with ultraviolet rays and / or visible rays.
Here, even if there is only one kind of material for forming the anisotropic optical film, a difference in refractive index occurs due to the difference in density. This is because a portion having a high UV irradiation intensity has a fast curing speed, and thus the cured material moves around the cured region, and as a result, a region having a higher refractive index and a region having a lower refractive index are formed.
In addition, (meth) acrylate means that either acrylate or methacrylate may be sufficient.

  The radically polymerizable compound mainly contains one or more unsaturated double bonds in the molecule, and specifically includes epoxy acrylate, urethane acrylate, polyester acrylate, polyether acrylate, polybutadiene acrylate, silicone acrylate, and the like. An acrylic oligomer called by name, 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, Opentyl glycol diacrylate, 1,6-hexanediol diacrylate, EO adduct diacrylate of bisphenol A, trimethylolpropane triacrylate, EO modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylol Examples thereof include acrylate monomers such as propanetetraacrylate and dipentaerythritol hexaacrylate. In addition, these compounds may be used alone or in combination. Similarly, although methacrylate can be used, acrylate is generally preferable to methacrylate because it has a higher photopolymerization rate.

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

  Further, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-dioxane, di (3,4-epoxycyclohexylmethyl) adipate, di (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl-3 ′, 4′-epoxy-6′-methyl Cyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, di (3,4-epoxycyclohexylmethyl) ether of ethylene glycol, ethylenebis (3,4-epoxycyclohexanecarboxylate), lactone modification 3, -Epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, tetra (3,4-epoxycyclohexylmethyl) butanetetracarboxylate, di (3,4-epoxycyclohexylmethyl) -4,5-epoxytetrahydrophthalate, etc. Although the alicyclic epoxy compound of these is also mentioned, it is not limited to these.

  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 trimethylolpropane trivinyl ether. , Propenyl ether propylene carbonate and the like, but are not limited thereto. Vinyl ether compounds are generally cationically polymerizable, but radical polymerization is also possible by combining with acrylates.

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

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

(Photo-curable compound having a silicone skeleton)
It is preferable to use a photocurable compound having a silicone skeleton as the photocurable compound. A photocurable compound having a silicone skeleton is oriented and polymerized and solidified along with its structure (mainly ether bonds), and has a low refractive index region, a high refractive index region, or a low refractive index region and a high refractive index region. Form. By using a photocurable compound having a silicone skeleton, it becomes easy to bend the diffusion center axis, and the light condensing property in the front direction is improved.

In the low refractive index region, it is preferable that the silicone resin, which is a cured product of the photocurable compound having a silicone skeleton, is relatively increased. This makes it easier to bend the diffusion center axis, thereby improving the light condensing property in the front direction.
Since a silicone resin contains more silica (Si) than a compound having no silicone skeleton, the relative use of the silicone resin can be achieved by using an EDS (energy dispersive X-ray spectrometer) with this silica as an index. The amount can be confirmed.

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

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

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

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

  The refractive index difference (absolute value) between the low refractive index region and the high refractive index region is preferably 0.02 or more. More preferably, it is 0.03 or more, More preferably, it is 0.04 or more. As the refractive index difference increases, the degree of anisotropy increases, and it becomes easier to confirm whether a plate-like structure is formed with an optical microscope or the like.

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

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

Raw material for anisotropic optical film (blending amount, other optional components)
In this invention, the said photoinitiator is 0.01-10 weight part with respect to 100 weight part of photopolymerizable compounds, Preferably it is 0.1-7 weight part, More preferably, it is about 0.1-5 weight part. Blended. This is because when less than 0.01 parts by weight, the photo-curing property is lowered, and when blending more than 10 parts by weight, only the surface is cured and the internal curability is lowered, coloring, columnar structure This is because it inhibits the formation of. These photoinitiators are usually used by directly dissolving powder in a photopolymerizable compound, but if the solubility is poor, a photoinitiator dissolved beforehand in a very small amount of solvent at a high concentration is used. It can also be used. Such a solvent is more preferably photopolymerizable, and specific examples thereof include propylene carbonate and γ-butyrolactone. It is also possible to add various known dyes and sensitizers in order to improve the photopolymerizability. Further, a thermosetting initiator capable of curing the photopolymerizable compound by heating can be used in combination with the photoinitiator. In this case, by heating after photocuring, it can be expected to further accelerate the polymerization and curing of the photopolymerizable compound to complete it.

  In the present invention, the anisotropic diffusion layer can be formed by curing the above-described photo-curable compound alone or by mixing a plurality of the mixed compositions. The anisotropic diffusion layer of the present invention can also be formed by curing a mixture of a photocurable compound and a polymer resin that does not have photocurability. Polymer resins 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, polyvinyl Examples include butyral resin. These polymer resins and photo-curable compounds must have sufficient compatibility before photo-curing, but various organic solvents, plasticizers, etc. are used to ensure this compatibility. It is also possible. In addition, when using an acrylate as a photocurable compound, it is preferable from a compatible point to select as a polymer resin from an acrylic resin.

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

[process]
Next, the manufacturing method (process) of the anisotropic optical film of this invention is demonstrated. The above-mentioned photocurable composition is coated on a suitable substrate such as a transparent polyethylene terephthalate (PET) film to provide a coating film (photocurable composition layer). Although it dries as needed and a solvent is volatilized, it is preferable that the dry film thickness is 50-300 micrometers. The lower limit of the dry film thickness is more preferably 80 μm, still more preferably 100 μm. Increasing the film thickness tends to cause bending. For example, in order to form the bend twice or more, the film thickness is preferably 100 μm or more. On the other hand, the upper limit value of the dry film thickness is more preferably 200 μm, still more preferably 150 μm. Productivity improves as the film thickness decreases. About a lower limit and an upper limit of said dry film thickness, a preferable value, a more preferable value, and a still more preferable value can be combined suitably. A dry film thickness of less than 50 μm is not preferable because the light diffusibility obtained through the UV irradiation process described below is poor. On the other hand, when the dry film thickness exceeds 300 μm, the overall diffusibility is too strong and it becomes difficult to obtain the characteristic anisotropy of the present invention, and it is not preferable because it is not suitable for thinning applications. . Further, a release film and a mask to be described later are laminated on this coating film to form a photosensitive laminate.

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

(Stacking of masks)
In order to form the anisotropic optical film of the present invention, a mask can be laminated in order to prevent oxygen inhibition of the photocurable composition layer. The material of the mask is not particularly limited, but it is necessary to use a sheet that transmits at least part of incident ultraviolet rays. Examples of such sheets include transparent plastic sheets such as PET, TAC, PVAc, PVA, acrylic, and polyethylene, inorganic sheets such as glass and quartz, and patterning and ultraviolet rays for controlling the amount of ultraviolet rays transmitted to these sheets. It may also contain pigments that absorb water. When such a mask is not used, it is also possible to prevent oxygen inhibition of the photocurable composition layer by performing light irradiation in a nitrogen atmosphere.

(light source)
As a light source for irradiating a composition containing a photocurable compound, a short arc ultraviolet light source is usually used, and specifically, a high pressure mercury lamp, a low pressure mercury lamp, a metahalide lamp, a xenon lamp or the like is used. Is possible. The light beam applied to the composition containing the photocurable compound needs to include a wavelength capable of curing the photocurable compound. Usually, light having a wavelength centered at 365 nm of a mercury lamp is used. Any lamp can be used as long as the light source includes a wavelength close to the absorption wavelength of the photopolymerization initiator to be used. An anisotropic diffusion layer is formed by curing the photocurable composition layer.

  In order to make the parallel light beam 12 from the light from the UV light of the short arc described above, for example, a reflecting mirror is arranged behind the light source so that the light is emitted as a point light source in a predetermined direction, and the light is further emitted. Parallel light can be obtained by the Fresnel lens. A Fresnel lens is a lens in which a normal lens is divided into concentric regions to reduce the thickness, and has a saw-like cross section. When the light beam emitted from the point light source passes through the Fresnel lens, the directions of the light beams having different directions are unified in one direction to become parallel light beams. However, in order to obtain parallel UV emission light necessary for producing the anisotropic optical film of the present invention, a Fresnel lens is not necessarily required, and various methods including a laser can be used. .

  A part of the parallel light beam is converted into a linear light beam by causing the parallel light beam described above to enter the flat surface of the lenticular lens and to be emitted from the uneven surface of the lenticular lens. That is, a parallel light beam and a linear light beam can be obtained through the lenticular lens.

  The above-described UV irradiation method using a lenticular lens is one method for producing the anisotropic optical film of the present invention, and the present invention is not limited to this. In short, in order to form a specific internal structure in the photocurable composition layer, it is important to irradiate the photosensitive laminate with UV light that spreads in a flat fan shape.

  That is, a fine structure having a high and low refractive index according to the present invention is formed by the step of irradiating the photocurable composition layer with light spreading in a plane fan shape. In addition, the light to irradiate has a wavelength which can harden the said photocurable composition. In the irradiation step, it is preferable to use light obtained by diffusing parallel rays into a flat fan shape.

When producing the anisotropic optical film of the present invention, the illuminance of UV light that passes through the lenticular lens and the like and is irradiated on the photocurable composition layer is in the range of 0.01 to 100 mW / cm ² . It is preferable that it is in the range of 0.1 to 20 mW / cm ² . If the illuminance is 0.01 mW / cm ² or less, it takes a long time to cure, resulting in poor production efficiency. If the illuminance is 100 mW / cm ² or more, the photo-curing compound is cured too quickly to form a structure, This is because the desired anisotropic diffusion characteristic cannot be expressed.

  Although the irradiation time of UV is not particularly limited, it is 10 to 180 seconds, more preferably 30 to 120 seconds. Then, the anisotropic optical film of this invention can be obtained by peeling a release film.

The anisotropic optical film of the present invention is obtained by forming a specific internal structure in the photocurable composition layer by irradiating low-illuminance UV light for a relatively long time as described above. For this reason, unreacted monomer components remain by such UV irradiation alone, and stickiness may occur, which may cause problems in handling properties and durability. In such a case, the residual monomer can be polymerized by additional irradiation with UV light having a high illuminance of 1000 mW / cm ² or more. The UV irradiation at this time is preferably performed from the opposite side of the mask side.

  The means for obtaining the internal bending structure in the anisotropic optical film of the present invention is not limited, but in the thickness direction of the photocurable composition layer when the composition containing the photocurable compound is cured. A method obtained by giving a temperature distribution is effective. The photocurable composition layer here refers to the state before the anisotropic diffusion layer is formed. That is, the photocurable composition layer refers to a state before the composition containing the photocurable compound is cured. For example, it is possible to generate a temperature distribution in the thickness direction of the composition layer by applying cool air to the surface side on which ultraviolet rays are incident to cool the substrate and heating the substrate side with various temperature control plates. The refractive index of the photocurable composition changes with temperature, and the photocurable composition bends as the irradiated ultraviolet rays pass through the interior. The bending angle, position, and direction can be changed by the refractive index of the composition, the reaction rate, the temperature gradient, and the like. Further, the number of the main bends can be adjusted by adjusting the film thickness. Here, the reaction rate is appropriately adjusted depending on the reactivity of the composition itself, the viscosity, the intensity of ultraviolet rays, the type and amount of the initiator, and the like.

Display Device The anisotropic optical film of the present invention is a liquid crystal display device (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), a cathode ray tube display device (CRT), a surface electric field display (SED), an electronic paper. It can be applied to such a display device. It is particularly preferably used for a liquid crystal display (LCD). The anisotropic optical film of the present invention is formed by curing a photocurable compound having a silicone skeleton, but there are few problems of adhesive strength, and it can be placed at a desired place via an adhesive layer or an adhesive layer. Can be used together.
The anisotropic optical film of the present invention can be preferably used for a transmissive, reflective, or transflective liquid crystal display device.

  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 0.2 mm was formed with a curable resin on the entire periphery of the edge of a PET film (trade name: A4300, manufactured by Toyobo Co., Ltd.) having a thickness of 100 μm and a size of 76 × 26 mm. This was filled with the following photocurable resin composition and covered with another PET film. Silicone urethane acrylate (refractive index: 1.460, weight average molecular weight: 5,890) 20 parts by weight (trade name: 00-225 / TM18, manufactured by RAHN)
30 parts by weight of neopentyl glycol diacrylate (refractive index: 1.450) (manufactured by Daicel Cytec Co., Ltd., trade name Ebecryl 145)
Bisphenol A EO adduct diacrylate (refractive index: 1.536) 15 parts by weight (manufactured by Daicel Cytec, trade name: Ebecyl 150)
・ Phenoxyethyl acrylate (refractive index: 1.518) 40 parts by weight (manufactured by Kyoeisha Chemical Co., Ltd., trade name: light acrylate PO-A)
・ 2,2-dimethoxy-1,2-diphenylethane-1-one 4 parts by weight (manufactured by BASF, trade name: Irgacure 651)
A 0.2mm-thick liquid film sandwiched between PET films was placed on a hot plate heated to 80 ° C, and the surface was cooled by sending air from a blower. From the top, a UV spot light source (Hamamatsu Photonics) UV light obtained by converting a parallel light beam emitted from an irradiation unit for incident light (manufactured by Co., Ltd., product name: L2859-01) into a linear light beam through a lenticular lens is irradiated vertically for 1 minute with an irradiation intensity of 10 mW / cm ^2. Thus, an anisotropic diffusion film of Example 1 having a large number of linear fine regions bent in the thickness direction as shown in FIG. 1 was obtained (however, the diffusion center axis, the bending angle, etc. are different from those in FIG. 1). ). From there, the PET film was peeled off to obtain the anisotropic diffusion film of the present invention.

[Example 2]
An anisotropic diffusion film of Example 2 was obtained in the same manner as in Example 1 except that the following photocurable resin composition was used.
Silicone urethane acrylate (refractive index: 1.460, weight average molecular weight: 5,890) 45 parts by weight (trade name: 00-225 / TM18, manufactured by RAHN)
Bisphenol A EO adduct diacrylate (refractive index: 1.536) 15 parts by weight (manufactured by Daicel Cytec, trade name: Ebecyl 150)
・ Phenoxyethyl acrylate (refractive index: 1.518) 40 parts by weight (manufactured by Kyoeisha Chemical Co., Ltd., trade name: light acrylate PO-A)
・ 2,2-dimethoxy-1,2-diphenylethane-1-one 4 parts by weight (manufactured by BASF, trade name: Irgacure 651)

[Example 3]
Example 2 was carried out in the same manner as in Example 1 except that the following photocurable resin composition was used and that ultraviolet rays converted into linear rays were irradiated at an angle of about −6 ° from the normal direction of the liquid film. An anisotropic diffusion film was obtained.
Silicone urethane acrylate (refractive index: 1.460, weight average molecular weight: 5, 8
90) 35 parts by weight (trade name: 00-225 / TM18, manufactured by RAHN)
-Trimethylolpropane triacrylate (refractive index :) 10 parts by weight-Bisphenol A EO adduct diacrylate (refractive index: 1.536) 10 parts by weight (manufactured by Daicel Cytec, trade name: Ebecyl 150)
・ Phenoxyethyl acrylate (refractive index: 1.518) 45 parts by weight (manufactured by Kyoeisha Chemical Co., Ltd., trade name: light acrylate PO-A)
・ 2,2-dimethoxy-1,2-diphenylethane-1-one 4 parts by weight (manufactured by BASF, trade name: Irgacure 651)

[Comparative Example 1]
An anisotropic diffusion film of Comparative Example 1 was obtained in the same manner as in Example 1 except that the following photocurable resin composition was used and the heating temperature by the hot plate was changed to 30 ° C.
-Epoxy acrylate (refractive index: 1.556) 20 parts by weight (manufactured by Daicel Cytec, trade name: Ebecyl 3700)
・ Phenoxyethyl acrylate (refractive index: 1.518) 40 parts by weight (manufactured by Kyoeisha Chemical Co., Ltd., trade name: light acrylate PO-A)
Polyether acrylate (refractive index: 1.462) 40 parts by weight (manufactured by Daicel Cytec, trade name: Ebecyl 230)
・ 3 parts by weight of 2,2-dimethoxy-1,2-diphenylethane-1-one (manufactured by BASF, trade name: Irgacure 651)

The measurement of the weight average molecular weight (Mw) of the silicone, urethane, and acrylate used in Examples 1 to 3 was performed under the following conditions using a GPC method as a molecular weight in terms of polystyrene.
Degasser: DG-980-51 (manufactured by JASCO Corporation)
Pump: PU-980-51 (manufactured by JASCO Corporation)
Autosampler: AS-950 (manufactured by JASCO Corporation)
Thermostatic chamber: C-965 (manufactured by JASCO Corporation)
Column: Shodex KF-806L x 2 (made by Showa Denko KK)
Detector: RI (SHIMAMURA YDR-880)
Temperature: 40 ° C
Eluent: THF
Injection volume: 150 μl
Flow rate: 1.0ml / min
Sample concentration: 0.2%

(Section observation of anisotropic diffusion film)
The anisotropic optical films obtained in Examples 1 to 3 and the comparative example were sectioned along the A axis in FIG. 1A, and the cross section was observed with a microscope.

The results obtained from the above observation are shown in FIGS. 5 shows the results of the cross-sectional observation of Example 1, FIG. 6 shows the results of Example 2, FIG. 7 shows the results of Example 3, and FIG. In Examples 1 to 3, it can be seen that the extension of the low refractive index region and the high refractive index region in the film thickness direction is bent. When this cross-sectional observation is analyzed, in Example 1, it can be determined that the main bending is one time and the layer structure is two layers, and in Examples 2 and 3, the main bending is two times and the layer structure is three layers. In addition, the bending angle of Example 1 is relatively small at 9 °, but in Example 2, it is large as +12 and −17 °. In addition, in Example 3, bending at a larger angle of + 17 ° and −23 ° is confirmed. Is done. On the other hand, in the comparative example 1, it turns out that bending is not seen but it extends substantially linearly.

(Evaluation of anisotropic diffusion film)
The anisotropic diffusion films of the examples and comparative examples were evaluated using a variable angle photometer goniophotometer (manufactured by Genesia Co., Ltd.) capable of arbitrarily changing the light projection angle of the light source and the light reception angle of the light receiver. The light-receiving part was fixed at a position where it received straight light from the light source, and the anisotropic diffusion films obtained in Examples and Comparative Examples were set in the sample holder therebetween. As shown in FIG. 15, the sample was rotated as the rotation axis (L), and the amount of linear transmitted light corresponding to each incident angle was measured. By this evaluation method, it is possible to evaluate in which angle range the incident light is diffused. The rotation axis (L) is the same axis as the BB axis in the sample structure shown in FIG. 14 or FIG. The linear transmitted light amount was measured by measuring the wavelength in the visible light region using a visibility filter.

The result of the Example obtained by the said measurement was shown in FIGS. 9-11, and the result of the comparative example was shown in FIG. FIG. 9 shows Example 1, FIG. 10 shows Example 2, FIG. 11 shows Example 3, and FIG. 12 shows Comparative Example 1, and shows the dependence on incident light by measuring the amount of linear transmitted light.
Table 1 summarizes the optical characteristics, and Table 2 summarizes the inclination and bending angle of the diffusion center axis.

  From FIGS. 9-11, any anisotropic diffusion film shows incident light dependence, shows that the amount of transmitted light is low and the diffusion is strong in a range close to the incident angle of UV light at the time of photocuring during production, At other incident angles, the amount of transmitted light is high and the diffusion is weak. In the anisotropic diffusion film of Examples 1-3, it has shown that a spreading | diffusion is strong with the incident light of a wider range than the anisotropic diffusion film of the comparative example 1. FIG. Further, it is shown that the range of incident light diffused in the order of Example 1 <Example 2 <Example 3 is wide. In particular, the diffusion range of Example 2 and Example 3 is very wide, and is related to the size of the bending angle and the number of bendings of the internal structure. This can also be seen from the fact that the values of Example 2 and Example 3 shown in “Angle range of incident light diffusion range” in Table 1 are larger than those of Comparative Example 1 and Example 1. The anisotropic optical film of the present invention has an optical profile that could not be achieved with a single film (one anisotropic diffusion layer) of a conventional anisotropic optical film. The optical loss is less than in the case of stacking, and it is advantageous in terms of productivity and cost. In addition, according to the present invention, since there is no large unevenness in the optical profile, an anisotropic optical film that does not give an unnatural impression can be provided.

  As described above, according to the present invention, it is possible to provide an anisotropic diffusion film having a large amount of change in the amount of linear transmitted light depending on the incident angle of the light beam, and the anisotropic diffusion film has a range of diffused incident light. And the range of diffusion of the light distribution is similarly wide, and when used in various display devices, visibility can be improved.

3 Photoreceptors 4, 41, 42, 43, 410, 411, 412, 413, 414, 420, 421, 422, 423, 424 Low refractive index region 5, 50 Anisotropic optical film 5a Upper surface 5b Lower surface 6 High refractive index Region 7 Anisotropic diffusion layer 40 Plate-like structure 51 Linear light source 71 Upper part 72 Middle part 73 Lower part

Claims (8)

One anisotropic diffusion layer has at least a low refractive index region and a high refractive index region, and on the surface (XY plane) of the one anisotropic diffusion layer, the low refractive index region and the The high refractive index regions are alternately arranged, and the cross section of the single anisotropic diffusion layer has a structure in which the low refractive index region and the high refractive index region are bent in the thickness direction (Z direction). And
The bent structure is obtained because the inclination of the first diffusion center axis is different from the inclination of the second diffusion center axis, and from the inclination of the first diffusion center axis and the inclination of the second diffusion center axis. An anisotropic optical film having a plurality of obtained bending angles in the X direction. The bent structure is obtained from the fact that the inclination of the first diffusion center axis and the inclination of the second diffusion center axis are different, and from the inclination of the first diffusion center axis and the inclination of the second diffusion center axis. The anisotropic optical film according to claim 1, wherein a plurality of obtained bending angles having different angles exist in the X direction. The anisotropic optical film according to claim 1 or 2, wherein a plurality of bending angles in the X direction are gradually increased. 2. A structure in which an interface between the low-refractive index region and the high-refractive index region continuously exists without being interrupted in the thickness direction of the one anisotropic diffusion layer. The anisotropic optical film as described in any one of -3. The bending direction of the low refractive index region and the high refractive index region is gradually changed without interruption over the thickness direction of the one anisotropic diffusion layer. The anisotropic optical film as described in any one of items. The incident angle at which the maximum linear transmittance at an incident angle at which the linear transmittance of the one anisotropic diffusion layer is maximum is 50% or more, and the linear transmittance of the one anisotropic diffusion layer is minimum. The angle range of the diffusion range of incident light with respect to the linear transmittance at which the minimum linear transmittance is 20% or less and the difference between the maximum linear transmittance and the minimum linear transmittance is ½ or less is 40 °. It is -80 degrees, The anisotropic optical film as described in any one of Claims 1-5 characterized by the above-mentioned. The anisotropy according to any one of claims 1 to 6, wherein an absolute value of a bending angle between the first diffusion center axis and the second diffusion center axis is 10 to 40 °. Optical film. The inclination of at least one diffusion center axis of the first diffusion center axis and the second diffusion center axis is in the range of ± 5 °, and the inclination of another diffusion center axis is −15 ° to −5 °. Or it exists in the range of +5 degrees-+15 degrees, The anisotropic optical film as described in any one of Claims 1-7 characterized by the above-mentioned.

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