JP2017181829A - Anisotropic optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic optical film that has balance of optical characteristics, including light diffusivity, optimized by suppressing glare and abrupt change in brightness.SOLUTION: An anisotropic optical film according to the present invention varies in quantity of transmitted light with an angle of incident light, and the anisotropic optical film has at least one anisotropic light diffusion layer, which has a plurality of louver rod structures and a matrix region, the louver rod structures being sectioned, orthogonally to a column axial direction, in a substantially round-corner rectangular shape such that both ends of two substantially parallel lines are connected with substantially arc lines.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an anisotropic optical film.

  Members having light diffusibility (light diffusive members) 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). As the light diffusion expression mechanism of the light diffusing member, light diffusion due to unevenness formed on the surface (surface light diffusion), light diffusion due to the refractive index difference between the matrix resin and the fine particles dispersed therein (internal light diffusion), And by both surface light diffusion and internal light diffusion. However, these light diffusive members are generally isotropic in light diffusivity, and the light diffusibility of the transmitted light does not differ greatly even if the incident light angle is slightly changed.

  On the other hand, an 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, that is, the amount of transmitted light can be changed according to the incident light angle. It has been. As such an anisotropic optical film, an assembly of a plurality of rod-like cured regions extending in parallel with a predetermined direction P inside a resin layer made of a cured product of a composition containing a photocurable compound An anisotropic diffusion medium in which a body is formed is disclosed (for example, see Patent Document 1). In the following, in this specification, an assembly of a plurality of rod-shaped hardened regions extending in parallel to a predetermined direction as described in Patent Document 1 is referred to as a “pillar structure region”, and the pillar structure region One of the structures is referred to as “pillar structure”, and the structure of the anisotropic light diffusion layer or anisotropic optical film in which the pillar structure region is formed is referred to as “pillar structure”.

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

  However, an anisotropic optical film with a pillar structure has a viewing angle that extends almost equally in all directions, but cannot meet the demand for a wider viewing angle in a certain direction (for example, the horizontal direction). When trying to widen the diffusion angle, there is a problem in that the front luminance decreases due to the diffusion of light.

  On the other hand, as an anisotropic optical film, a region having a different refractive index, not the pillar structure described above, is a linear array of a large number of rod-like light sources and point light sources used for structure formation (hereinafter referred to as these A film-like composition is disclosed in which a layer having a periodic microstructure is formed in a state of being oriented in parallel with a major axis direction such as a light source (referred to as a linear light source) (see, for example, Patent Document 2). Hereinafter, in this specification, as described in Patent Document 2, an assembly of a plurality of microstructures periodically present in a state of being aligned parallel to the long axis direction of a linear light source is referred to as a “louver structure region”. And a structure in the louver structure region is referred to as a “louver structure”, and an anisotropic light diffusion layer or an anisotropic optical film in which the louver structure region is formed is referred to as a “louver structure”. I will call it.

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

  Furthermore, since the pillar structure has a pillar structure, the linear transmittance (the amount of transmitted light in the linear direction when entering the anisotropic optical film from a certain incident light angle (hereinafter referred to as “linear transmitted light amount”). The ratio of the amount of incident light (hereinafter referred to as “incident light amount”) tends to be lower than the louver structure, and the louver structure has a louver structure. The linear transmittance tends to be higher than that of the pillar structure.

  With these problems as problems, Patent Document 3 discloses an anisotropic optical film having an intermediate structure between the pillar structure and the louver structure. Hereinafter, the structure of this anisotropic optical film is referred to as a “louver rod structure”. In this patent document, as a technique for obtaining a louver rod structure, a thin plate-like photopolymerized cured product having a plurality of columnar structures is stretched in a uniaxial direction along the surface of the thin plate, and the cross-sectional shape of the columnar structures is obtained. A method of extending in a uniaxial direction is adopted.

JP 2005-265915 A Japanese Patent No. 4802707 JP 2012-11709 A

  However, in the conventional manufacturing method of the louver rod structure, it is difficult to finely adjust the shape of the louver rod structure for achieving desired optical characteristics. Accordingly, an object of the present invention is to provide an anisotropic optical film that suppresses a sudden change in glare and brightness and is optimized in the balance of optical characteristics including light diffusibility.

The inventors of the present invention have intensively studied to solve the above problems. As a result, in the anisotropic light diffusing layer of the anisotropic optical film, the shape of the cross section perpendicular to the column axis direction (thickness direction of the anisotropic light diffusing layer) of the plurality of louver rod structures is optimized. The inventors have found that the above problems can be solved by using a rectangular shape, and have completed the present invention. That is,
The present invention (1) is an anisotropic optical film in which the amount of transmitted light changes depending on the incident light angle of light, and the anisotropic optical film has at least one anisotropic light diffusion layer, and the anisotropic light The diffusion layer has a plurality of louver rod structures and a matrix region, and the cross-sectional shape perpendicular to the column axis direction of the louver rod structures has two arcs parallel to each other at substantially arcs. It is an anisotropic optical film characterized by having a substantially rounded rectangular shape.
In the present invention (2), the parallel line width of the two substantially parallel lines is L, the long diameter line width of the substantially long diameter line which is the maximum width of the substantially rounded rectangle is Y, and (Y−L) / 2 is set. In the case of r, the anisotropic optical film according to (1), wherein Formula 2r <L <10r is satisfied.
The present invention (3) is the anisotropic optical film according to (1) or (2), wherein the thickness of the anisotropic light diffusion layer is in the range of 10 μm to 100 μm.
The anisotropy according to any one of (1) to (3), wherein the length of r is in a range of 0.01 μm or more and less than 0.4 μm in the present invention (4). It is an optical film.

  According to the present invention, it is possible to provide an anisotropic optical film in which a sharp change in glare and luminance is suppressed and the balance of optical characteristics including light diffusibility is optimized.

It is a schematic diagram which shows an example of a structure of the anisotropic light-diffusion layer concerning this invention, (a) is an anisotropic light-diffusion layer plane shape schematic diagram, (b) is anisotropic light diffusion cut | disconnected by the AA line of (a) It is a thickness direction cross-sectional schematic diagram of a layer. It is a schematic diagram which shows an example of a structure of the anisotropic diffused layer in the anisotropic optical film of this invention, and is a schematic diagram showing a substantially rounded rectangular shape. It is explanatory drawing which shows the evaluation method of the linear transmitted light amount and linear transmittance of an anisotropic optical film. It is a graph for demonstrating evaluation of the linear transmitted light amount of an anisotropic optical film. It is a schematic diagram which shows an example of the photomask pattern used for this invention. It is a schematic diagram which shows an example of the whole photomask used for this invention. It is an external appearance photograph of the photomask used in the present invention. It is a partial surface photograph of the photomask pattern used for this invention. It is explanatory drawing which shows the evaluation method of the rapid change of the brightness | luminance of an anisotropic light-diffusion layer (anisotropic optical film).

  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 light diffusion layer of the anisotropic optical film is cured.

  The “diffusion center axis” means a direction in which the light diffusibility coincides with the incident light angle of light having substantially symmetry with respect to the incident light angle when the incident light angle of light is changed. The reason for having “substantially symmetrical” is that the anisotropic light diffusion layer of the present invention does not have strictly light diffusive symmetry. 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 light angle.

The linear transmittance is expressed by the following formula.
Linear transmittance (%) = (Linear transmitted light amount / incident light amount) × 100

  The “light” in the present invention is an electromagnetic wave including visible light having a wavelength of 380 nm to 780 nm and ultraviolet light having a wavelength of 100 nm to 400 nm.

  The contents of the present invention will be described below with reference to the drawings.

<< Structure of anisotropic optical film >>
<Overall structure>
The anisotropic optical film according to the present invention includes at least an anisotropic light diffusion layer. Therefore, it may be an optical laminate in which a plurality of layers including an anisotropic light diffusion layer are laminated.
Also, depending on the application, only the anisotropic light diffusion layer is a single layer, and if it does not include other layers, in this case, the anisotropic light diffusion layer becomes an anisotropic optical film.

<Anisotropic light diffusion layer>
FIGS. 1-2 is a schematic diagram which shows an example of a structure of the anisotropic light-diffusion layer 1 in the anisotropic optical film of this invention. 1A is a schematic plan view of the anisotropic light diffusion layer 1, and FIG. 1B is a cross-sectional schematic view in the thickness direction of the anisotropic light diffusion layer 1 cut along the line AA in FIG. 1A. FIG. 2 and FIG. 2 are schematic diagrams showing a substantially rounded rectangular shape.

  As shown in FIG. 1, the anisotropic light diffusion layer 1 has a plurality of louver rod structures 2 and a matrix region 3. The plurality of louver rod structures 2 have a regular distribution in the anisotropic light diffusion layer 1 in FIG. 1A, but may have an irregular distribution. Whether it is regular or not depends on the pattern of the photomask described later.

Further, as shown in FIG. 1B, the anisotropic light diffusion layer 1 has a structure in which a plurality of louver rod structures 2 and matrix regions 3 are alternately arranged in the plane direction of the anisotropic light diffusion layer 1. Is formed.
Further, FIG. 1B shows a form in which a plurality of louver rod structures 2 extend in parallel to the thickness direction of the anisotropic light diffusion layer 1. The cross-sectional shape with respect to the thickness direction is not particularly limited as long as the optical characteristics described later are satisfied, and the linear shape of the louver rod structure 2 in the column axial direction is different, for example, a wavy shape, an inclined shape, or a bent shape. It may be a shape or a mixture of shapes.

  Further, since the plurality of louver rod structures 2 are irregularly or regularly distributed over the entire region in the anisotropic light diffusing layer 1, the obtained optical characteristics can be obtained at any part of the anisotropic light diffusing layer 1. Even if measured, it is substantially the same.

Here, the refractive index of the matrix region 3 only needs to be different from the refractive indexes of the plurality of louver rod structures 2, and how much the refractive index differs is not particularly limited, and which is the high refractive region. , Relative.
That is, when the refractive index of the matrix region 3 is lower than the refractive index of the plurality of louver rod structures 2, the matrix region 3 is a low refractive index region, an aggregate of the plurality of louver rod structures 2 (hereinafter referred to as “louver rod structure region”). ") Is a high refractive index region.
Conversely, when the refractive index of the matrix region 3 is higher than the refractive index of the plurality of louver rod structures 2, the matrix region 3 is a high refractive index region and the louver rod structure region is a low refractive index region.

[Louvre rod structure]
The plurality of louver rod structures 2 in the anisotropic light diffusion layer 1 of the present invention shown in FIG. 1 are characterized in that the cross-sectional shape perpendicular to the column axis direction has a substantially rounded rectangle.
Specifically, as shown in FIG. 2, the substantially rounded rectangle has a shape in which both ends of two substantially parallel lines having a parallel line width L are connected by a substantially arc. The long diameter line width Y and the parallel line width L of the substantially long diameter line whose maximum width of the substantially rounded rectangle is Y can be confirmed by observing the anisotropic light diffusion layer (anisotropic optical film) with an optical microscope. it can.
In addition, as shown in FIG. 2, S, which is a substantially rounded rectangular width in a direction perpendicular to the long-diameter line width Y of the substantially rounded rectangle, is hereinafter referred to as a short-diameter line width.
The shape of the substantially rounded rectangular shape only needs to satisfy the regulations and formulas described later, and the linear shape or curved shape of the outer peripheral portion of the substantially rounded rectangular shape is another shape, for example, a wavy shape or an inclined shape, Each shape may be mixed.

  By having the above shape, the lens effect that the transmitted light of the anisotropic optical film diffuses moderately is exhibited, the glare and the sudden change of luminance due to light interference are suppressed, and the balance of optical characteristics including light diffusivity is achieved. Can be optimized.

(Relationship between Y and S)
In the present invention, since the cross-sectional shape orthogonal to the column axis direction of the plurality of louver rod structures is a substantially rounded rectangle, the relationship between the long diameter line width Y and the short diameter line width S is S <Y Need to be. In addition, the long diameter line width Y is preferably 0.5 to 50.0 μm, more preferably 1.0 to 10.0 μm, and further preferably 1.0 to 5.0.0 μm. 0 μm. If it is less than 0.5 μm, the uncured resin composition layer of the anisotropic light diffusing layer cannot be faithfully irradiated with the photomask pattern, which may be easily affected by the optical proximity effect, and may exceed 50.0 μm. In such a case, glare due to light interference may easily occur.

(Length of r)
In the present invention, the length of r in the substantially rounded rectangle is a value that satisfies the relationship r = (Y−L) / 2 in the relationship between the major diameter line width Y and the parallel line width L. . The length of r is preferably 0.01 or more and less than 0.4 μm, and more preferably 0.05 μm to 0.3 μm. When it is less than 0.01 μm, the light diffusibility is lowered, and when it is 0.4 μm or more, the amount of transmitted light may be reduced. Hereinafter, this r is referred to as a rounded radius width.

(Value of L / r)
It is preferable that a value obtained by dividing the parallel line width L by the rounded radius width r is in a range of more than 2 and less than 10. More preferably, it is in the range of 2-8. If it is 2 or less, the amount of transmitted light is reduced, and if it is 10 or more, the light diffusibility may be reduced.

(S / r value)
A value obtained by dividing the minor diameter line width S by the rounded radius width r is preferably in the range of 0.4 to 10.0. More preferably, it is the range of 0.8-5.0, More preferably, it is the range of more than 1.3 and 2.5 or less. If it exceeds 10.0, the light diffusibility decreases, and if it is less than 0.4, the amount of transmitted light decreases.

(Thickness T of anisotropic light diffusion layer)
The thickness T of the anisotropic light diffusion layer 1 (see FIG. 1B) is preferably 10 μm to 100 μm. By setting the anisotropic light diffusing layer thickness T in the above range, the cost problem is reduced and the contrast of the image is sufficient. Further, the lower limit value of the thickness T of the anisotropic light diffusion layer 1 is more preferably 15 μm or more. As the thickness T decreases, the balance between light diffusion and light condensing performance may become insufficient. On the other hand, the upper limit value of the thickness T of the anisotropic diffusion layer 1 is more preferably 70 μm or less. As the thickness T increases, the cost of the material increases and the time required for manufacturing increases, and the image tends to blur due to reflection and refraction of light in the thickness T direction. And the contrast tends to be lowered.

  In this invention, it is preferable to have the structure where the interface of a some louver rod structure and a matrix area | region exists continuously without interruption over the thickness direction of one layer of anisotropic light-diffusion layer. The plurality of louver rod structures and the interface of the matrix region are connected to each other, so that light diffusion and collection by light transmission, reflection, and refraction continue while passing through the anisotropic light diffusion layer. This increases the efficiency of light diffusion and light collection. On the other hand, in the cross section in the thickness direction of the anisotropic light diffusing layer, it is not preferable that the plurality of louver rod structures and matrix regions are mainly mottled like spots, because it becomes difficult to collect light. .

If the linear transmittance of light incident on the anisotropic light diffusing layer at the incident light angle at which the linear transmittance of the anisotropic light diffusing layer (anisotropic optical film) is maximum is defined as “maximum linear transmittance”, anisotropic light diffusion The layer preferably has a maximum linear transmittance of 35% to 95%. The upper limit value of the maximum linear transmittance of the anisotropic light diffusion layer is more preferably 80% or less, and further preferably 70% or less.
On the other hand, the lower limit value of the maximum linear transmittance is more preferably 40% or more, and further preferably 50% or more.

  By setting the maximum linear transmittance within the specified range, an appropriate optical anisotropy can be obtained, so that the application range of the anisotropic optical film can be expanded. For example, when an anisotropic optical film is applied to a display device, if the optical anisotropy is too strong, the light diffusion and condensing property in the horizontal direction of the display device is excellent, but the light diffusion and condensing in the vertical direction is excellent. However, the anisotropic optical film of the present invention maintains the excellent light diffusion and condensing properties in the horizontal direction by having the maximum linear transmittance specified above. Thus, the light can be sufficiently diffused and collected in the vertical direction.

  In addition, if the linear transmittance of light incident on the anisotropic light diffusing layer at an incident light angle at which the linear light transmittance of the anisotropic light diffusing layer is minimum is defined as “minimum linear transmittance”, the anisotropic light diffusing layer has the minimum linear transmittance. The rate is preferably 25% or less. The upper limit of the minimum linear transmittance of the anisotropic light diffusion layer is more preferably 20% or less, and further preferably 15% or less. Although a lower limit is not limited, For example, it is 0%.

Here, the linear transmittance can be measured by the method shown in FIG.
First, as shown in FIG. 3, the anisotropic light diffusion layer 10 (sample) is disposed between the light source 4 and the detector 5. In this embodiment, the incident light angle when the irradiation light I from the light source 4 enters from the plane normal direction of the anisotropic light diffusion layer 10 is set to 0 °. The anisotropic light diffusing layer 10 includes the direction of the rotation axis P of the anisotropic light diffusing layer 10 shown in FIG. 3 and the AA line of the anisotropic light diffusing layer (anisotropic optical film) shown in FIG. The light source 4 and the detector 5 are fixed so that the directions coincide with each other and can be arbitrarily rotated about the rotation axis P.

  That is, according to this method, a sample is disposed between the light source 4 and the detector 5, and the incident light angle from the light source 4 to the sample is rotated while rotating the sample around the rotation axis P of the sample. The detector 5 measures the linear transmitted light amount and the linear transmittance (linear transmittance = linear transmitted light amount of the detector when there is a sample / linear transmitted light amount of the detector when there is no sample). An optical profile is obtained from the obtained data, and the maximum linear transmittance and the minimum linear transmittance are obtained from this optical profile. In addition, when the linearly transmitted light amount and the linear transmittance are measured for each incident light angle so that the axis orthogonal to the AA line coincides with the rotation axis P shown in FIG. 3, the incident light is incident as shown in FIG. The linear transmitted light amount near zero is shown regardless of the light angle.

(Diffusion width)
The diffusion width is an index of light diffusibility.
From the above, the maximum linear transmittance and the minimum linear transmittance of the anisotropic light diffusion layer (anisotropic optical film) are obtained from the optical profile, and 2 for the linear transmittance that is an intermediate value between the maximum linear transmittance and the minimum linear transmittance. Determine the width of the incident light angle range between the two incident light angle values (inside the two incident light angles in the optical profile). This width becomes the diffusion width that is the light diffusion region, and the width of the incident light angle range excluding the width (outside the two incident light angles in the optical profile) becomes the non-diffusion region.
Here, in the optical profile, the incident light angle is indicated by a negative value and a positive value with reference to an incident light angle of 0 °, which is a case where the anisotropic light diffusion layer is incident from the plane normal direction. Therefore, the incident light angle may be a negative value. If the two incident light angles have a positive value and a negative value, the sum of the absolute value of the negative value and the positive value becomes the diffusion width.
When the two incident light angles are both positive values, the difference obtained by subtracting the smaller positive value from the larger positive value is the diffusion width. When the two incident light angles are both negative values, the absolute value of each is taken, and the difference obtained by subtracting the smaller value from the larger value is the diffusion width.

  The diffusion width is preferably 30 ° to 80 °. If the diffusion width is less than 30 °, the light diffusibility of the anisotropic optical film is not at a practical level. A more preferable diffusion width is 40 ° to 70 °.

Although depending on the material forming the anisotropic light diffusion layer, the angle at which the plurality of louver rod structures diffuse light strongly depends on the column axis direction of the louver rod structure, that is, the inclination of the diffusion center axis, the louver rod structure This is when the difference between the inclination of the incident light and the traveling direction is in the range of approximately ± 10 °.
Further, when the louver rod structure is bent and extended in the column axis direction, a region where light is strongly diffused can be further expanded. This is because bending causes the louver rod structure to have a plurality of angular ranges in the column axis direction in which light is strongly diffused.
In addition, when there are a plurality of the bends, a region that strongly diffuses light can be formed continuously in the direction of the column axis. Therefore, light diffusion and collection can be performed with the light intensity kept substantially constant. Light property can be improved.

The angle (bending angle) when the column axis direction of the louver rod structure is bent is preferably 10 ° to 40 ° in order to obtain a sufficient region for diffusing light strongly.
Further, when the bending angle is 15 to 25 °, it is more preferable because the region where light is strongly diffused can be further expanded.

  The louver rod structure may be inclined. When the column axis direction of the louver rod structure has one inclination, the inclination is preferably in the range of ± 70 ° when the normal direction to the plane of the anisotropic light diffusion layer is 0 °. , Within a range of ± 35 °, more preferably within a range of ± 15 °. Depending on the material forming the anisotropic light diffusing layer, incident light smaller than -70 ° or larger than + 70 ° is likely to be reflected on the surface of the anisotropic light diffusing layer and hardly enters the anisotropic light diffusing layer. is there. By these ranges, the region where light is strongly diffused can be expanded.

  Further, when the column axis direction of the louver rod structure has a plurality of inclinations, each inclination may be within a range of ± 70 ° when the normal direction to the plane of the anisotropic light diffusion layer is 0 °. Is preferred. The number of the slopes is not limited, but is preferably between 2 and 5. This is because as the number of inclinations increases, the thickness of the anisotropic light diffusion layer increases in order to form the inclination, and the productivity decreases.

  Of the plurality of inclinations of the louver rod structure column axis direction, at least one is preferably in the range of ± 5 ° when the normal direction to the plane of the anisotropic light diffusion layer is 0 °. In addition, the other inclination is preferably in the range of −15 ° to −5 °, or + 5 ° to + 15 °. As a result, a region where light is strongly diffused can be further expanded. Furthermore, since the region where light is strongly diffused can be formed continuously in the direction of the column axis, the light diffusion and light condensing properties can be further enhanced while maintaining the light intensity substantially constant.

  The shape of the louver rod structure in which the column axis direction is bent may be such that the bent portion bends substantially linearly, gradually changes (for example, a curved shape), or steep. (For example, a linear shape) may be used. This makes it easier to obtain the effects of the present invention. Furthermore, in the present invention, it is preferable that the bending of the louver rod structure gradually changes without interruption in the column axis direction. By gradually changing without interruption, light can be diffused and collected efficiently. Such a structure in which the inclination in the column axis direction is bent can be combined with the shape adjustment of the substantially rounded rectangular shape of the louver rod structure to further optimize the balance of optical characteristics.

[Other layers]
It is good also as an anisotropic optical film which provided the other layer in one surface of the anisotropic light-diffusion layer. Examples of the 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.
Moreover, you may laminate | stack another layer sequentially. Further, other layers may be laminated on both surfaces of the anisotropic light 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 is obtained by forming an anisotropic light diffusion layer by irradiating an uncured resin composition layer of a specific photocurable resin composition with ultraviolet rays and / or visible rays under special conditions. Can be produced. Hereinafter, the raw material for the anisotropic light diffusion layer will be described first, and then the manufacturing process will be described.

<Raw material for anisotropic light diffusion layer>
The material forming the anisotropic light diffusing layer of the present invention comprises a photocurable compound selected from a macromonomer, polymer, oligomer or monomer having a radical polymerizable or cationic polymerizable functional group and a photoinitiator. It is a material that is polymerized and cured by irradiating the photocurable resin composition with ultraviolet rays and / or visible rays. Here, even if there is only one kind of photocurable compound forming the anisotropic light diffusing layer, a difference in refractive index is caused by a difference in density. The portion where the irradiation intensity of ultraviolet rays and / or visible light is strong has a fast curing speed, and therefore the cured material moves around the cured region, resulting in the formation of a region with a higher refractive index and a region with a lower refractive index. Because. In addition, (meth) acrylate means that either acrylate or methacrylate may be sufficient.

  Here, 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, and further preferably 0.04 or more. As the difference in refractive index increases, the degree of anisotropy increases, and it becomes easier to confirm whether a louver rod structure is formed with an optical microscope or the like.

[Photocurable compound]
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. These compounds may be used alone or in combination. Similarly, methacrylate can also be used, but in general, acrylate is preferred because it has a higher photopolymerization rate than methacrylate.

  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.

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

  Examples of the compound having a vinyl ether group include diethylene glycol divinyl ether, triethylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, hydroxybutyl vinyl ether, ethyl vinyl ether, dodecyl vinyl ether, 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.

In addition, the said cation polymeric compound may be used for each single-piece | unit, and multiple may be used in mixture.
Furthermore, a photocurable compound is not limited to the above. In addition, in order to cause a sufficient difference in refractive index, fluorine atoms (F) may be introduced into the photocurable compound in order to reduce the refractive index, and in order to increase the refractive index, sulfur atoms may be introduced. (S), bromine atoms (Br), and various metal atoms may be introduced. Further, as disclosed in Japanese Patent No. 4423040, an acrylic group or a surface of ultrafine particles made of a metal oxide having a high refractive index such as titanium oxide (TiO2), zirconium oxide (ZrO2), tin oxide (SnOx) It is also effective to add functional ultrafine particles into which a photopolymerizable functional group such as a methacryl group or an epoxy group is introduced to the photocurable compound.

(Photo-curable compound having a silicone skeleton)
In the present invention, 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 / cured in accordance 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 incline or bend the column axis direction of the louver rod structure, and light diffusion and light collection properties are improved. The low refractive index region corresponds to either the louver rod structure region or the matrix region, and the other corresponds to the high refractive index region.

  Here, 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. As a result, the column axis direction of the louver rod structure can be more easily inclined or bent, so that the light diffusion and condensing properties are further improved. Silicone resins contain more silicon (Si) than compounds that do not have a silicone skeleton. Therefore, using silicon as an index, an EDS (energy dispersive X-ray spectrometer) can be used to compare the relative amount of silicone resins. 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 is no particular limitation on the type and number of these functional groups, but the more functional groups, the higher the crosslink density and the greater the difference in refractive index, which is preferable, so having a polyfunctional acryloyl group or methacryloyl group. Is preferred. 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 this range, a sufficient photocuring reaction occurs, and the silicone resin is easily oriented in the anisotropic light diffusion layer. Furthermore, along with the orientation of the silicone resin, the column axis direction of the louver rod structure is easily inclined or 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 functional groups such as a polyether group, an acryloyl group, and a methacryloyl group. Moreover, in general formula (1), it is preferable that n is an integer of 1-500.

(Compound without silicone skeleton)
When an anisotropic light diffusion layer is formed by blending a photocurable compound having a silicone skeleton with a compound that does not have a silicone skeleton, the low refractive index region and the high refractive index region are easily separated and formed anisotropic. The degree of is strong and preferable. As the compound having no silicone skeleton, a thermoplastic resin or a thermosetting resin can be used in addition to the photocurable compound, or these can be used in combination.
As the photocurable compound, a polymer, oligomer, monomer or the like 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 polyesters, polyethers, polyurethanes, polyamides, polystyrenes, polycarbonates, polyacetals, polyvinyl acetates, acrylic resins and their copolymers and modified products. 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 and / or visible rays to form an anisotropic light diffusion layer. Mold. Examples of the thermosetting resin include epoxy resins, phenol resins, melamine resins, urea resins, unsaturated polyesters, copolymers thereof, and modified products. In the case of using a thermosetting resin, the photocurable compound having a silicone skeleton is cured by irradiation with ultraviolet rays and / or visible light, and then appropriately heated to thermoset the thermosetting resin to perform anisotropic light diffusion. Mold the layer. The most preferable compound having no silicone skeleton is a photocurable compound, which is easily separated from a low refractive index region and a high refractive index region, and a solvent as in the case of using a thermoplastic resin. This is because it is excellent in productivity, such as no need for a drying process and no need for a thermosetting process such as a thermosetting 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 in the range of 30:70 to 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 column axis direction of the louver rod structure can be easily tilted or 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, the phase separation is difficult to proceed, and the louver rod structure is difficult to be inclined or bent in the column axis direction. 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. Thereby, even if the mixing ratio of the materials is widened, the column axis direction of the louver rod structure can be easily inclined or bent.

[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 capable of polymerizing the cationic polymerizable compound is a compound capable of generating an acid by irradiation with ultraviolet rays and / or visible light, and polymerizing the cationic polymerizable compound with the generated acid. In general, onium salts and metallocene complexes are preferably used. As the onium salt, a diazonium salt, a sulfonium salt, an iodonium salt, a phosphonium salt, a selenium salt or the like is used, and an anion such as BF ₄ −, PF ₆ —, AsF ₆ —, SbF ₆ — or the like is used as these counter ions. 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. These compounds may be used alone or in combination.

  In this invention, the said photoinitiator is 0.01-10 weight part with respect to 100 weight part of photocurable compounds, More preferably, it is 0.1-7 weight part, More preferably, it is 0.1-5. It is preferable that about part by weight is blended. This is because if less than 0.01 parts by weight, the photocurability is reduced, and if more than 10 parts by weight is blended, in addition to the adverse effect that only the surface is cured and the internal curability is reduced, coloring, This is because the louver rod structure formation is inhibited. These photoinitiators are usually used by directly dissolving powder in a photocurable compound, but if solubility is poor, a photoinitiator dissolved in a very small amount of solvent in advance at a high concentration is used. It can also be used. Such a solvent is more preferably photocurable, and specific examples thereof include propylene carbonate and γ-butyrolactone. It is also possible to add various known dyes and sensitizers to improve photocurability. Further, in the case of a photocurable compound that can be cured by heat, a thermosetting initiator capable of curing the photocurable compound by heating can be used in combination with the photoinitiator. In this case, polymerization and curing of the photocurable compound can be further promoted by heating after photocuring.

[Other raw materials]
(Polymer resin)
In the present invention, it is possible to form an anisotropic light diffusing layer mainly by curing the above-described photocurable compound alone or by mixing a plurality of photocurable resin compositions. The anisotropic light diffusing layer of the present invention can also be formed by curing a mixture of polymer resins having no curability. Examples of polymer resins that can be used here include acrylic resins, styrene resins, styrene-acrylic copolymers, polyurethane resins, polyester resins, epoxy resins, cellulose resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, Examples include polyvinyl butyral resin. These polymer resins and 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 suitable from a compatible point to select as a polymer resin from an acrylic resin.

≪Process≫
Next, the manufacturing method (process) of the anisotropic optical film of this invention is demonstrated using FIGS. By sequentially performing the following steps, the cross-sectional shape having a plurality of louver rod structures and a matrix region and orthogonal to the column axis direction of the louver rod structures has both ends of two substantially parallel lines. An anisotropic optical film having a substantially rounded rectangular shape connected by a substantially arc can be obtained.
(1) A coating process in which a photocurable resin composition is coated on a substrate to provide a coating film (uncured resin composition layer) (2) A photomask is laminated on the uncured resin composition layer , Photomask lamination process (3) Parallel light acquisition process to obtain parallel light from light source (4) Photomask surface on uncured resin composition layer is irradiated with parallel light to polymerize and cure uncured resin composition layer Curing step (5) Other layer laminating step (optional) by laminating other layers on the anisotropic light diffusion layer according to the application

<Coating process>
A coating process suitable for the present invention is a coating film (uncured resin composition) in which a photocurable resin composition is coated on a suitable substrate such as a transparent polyethylene terephthalate (PET) film in a sheet form. This is a step of providing a material layer.
As coating, 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 photocurable resin composition has a low viscosity, a weir with a certain height can be provided around the base film, and the photocurable resin composition can be cast while being surrounded by the weir. In addition, it is suitable for a coating film to dry as needed and to volatilize a solvent.

<Photomask lamination process>
In order to form the cross-sectional shape orthogonal to the column axis direction of the plurality of louver rod structures of the anisotropic light diffusion layer in the anisotropic optical film of the present invention on the uncured resin composition layer, It is preferable to provide a step of laminating a photomask.
As the photomask, a substrate in which a desired substantially rounded rectangle is patterned according to a photomask manufacturing procedure can be used.
A specific photomask manufacturing procedure is as follows. First, a chromium film for forming a light shielding film that blocks ultraviolet rays is formed on the entire surface of a glass substrate to be a photomask. Thereafter, an electron beam resist (photosensitive material) is applied and baked, and then exposed, developed, and rinsed by an electron beam drawing apparatus to pattern the electron beam resist on the chromium film. Thereafter, an unnecessary chromium film is dissolved by etching, a hole through which ultraviolet rays are transmitted is formed, and then the resist is removed with a chemical solution, thereby completing a photomask.
Many substrates used for photomasks have a drawing pattern formed on glass or synthetic quartz using chromium as a light-shielding film as described above, but they are drawn on a transparent polymer film called an emulsion mask. It may be. In that case, it is preferable to form a light-shielding film with blackened metal silver instead of chromium.
The pattern size of the photomask varies depending on the conditions, but in the present invention, the pattern was produced with a size of 3 cm × 3 cm. FIG. 5 is a schematic diagram showing an example of the pattern of the photomask used in the present invention, and FIG. 6 is a schematic diagram showing an example of the entire photomask used in the present invention.
In FIG. 6, the size of the photomask is 5 inches × 5 inches, the pattern is divided into nine blocks, the pitch between each pattern is 0.85 cm, and the distance between the outer periphery of the photomask and the outer periphery of each pattern is 1 cm. is there.
In the present invention, by using a photomask, it is preferable that the cross-sectional shape perpendicular to the column axis direction of the plurality of louver rod structures of the anisotropic light diffusing layer is formed into a desired substantially rounded rectangular shape. However, if the photomask pattern dimension is smaller than the wavelength when the uncured resin composition layer is irradiated with parallel light, the photomask pattern cannot be faithfully irradiated onto the uncured resin composition layer. You may be affected by the effect. As a countermeasure against this, a technique of previously providing optical proximity correction (OPC) to the mask pattern of the photomask can be applied.
By using the photomask, the cross-sectional shape perpendicular to the column axis direction of the plurality of louver rod structures of the anisotropic light diffusion layer can be formed as a desired substantially rounded rectangular shape.
Further, the photomask also serves to prevent oxygen inhibition when the uncured resin composition layer is cured.

<Parallel beam acquisition process>
As a light source for irradiating the photomask surface on the uncured resin composition layer with ultraviolet rays and / or parallel rays of visible rays, a short arc ultraviolet ray generating light source is usually used, specifically, a high pressure mercury lamp, a low pressure Mercury lamps, metahalide lamps, xenon lamps and the like can be used. The light to be irradiated needs to include a wavelength capable of curing the photocurable resin composition, and usually a 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.

  In order to produce a parallel light beam from the light from the short arc ultraviolet ray generating light source, for example, a reflecting mirror is disposed 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 into the Fresnel. It can be made parallel rays by the lens. A Fresnel lens is a lens in which a normal lens is divided into concentric regions and the thickness is reduced, and has a saw-like cross section. When the light emitted as the point light source passes through the Fresnel lens, the directions of the light having different directions are unified into one direction and become parallel rays. However, in order to obtain the parallel light beam 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.

<Curing process>
In this step, the photomask surface on the uncured resin composition layer is irradiated with parallel light, and the uncured resin composition layer is polymerized and cured.
By making parallel rays of ultraviolet rays and / or visible rays incident from the photomask surface laminated on the uncured resin composition layer, polymerizing and curing the uncured resin composition layer, and then peeling the substrate An anisotropic optical film (anisotropic light diffusing layer) is used, or if necessary, the process is further advanced to another layer laminating process in which another layer is laminated on the anisotropic light diffusing layer. In addition, it is good also as an anisotropic optical film as it is, without peeling a base material.

The illuminance of the parallel rays by ultraviolet rays and / or visible rays applied to the uncured resin composition layer is preferably in the range of 0.01 mW / cm ^{2 to} 100 mW / cm ² , more preferably 0. The range is from ¹ mW / cm ^{2 to 20} mW / cm ² . Since illuminance takes a long time to cure is less than 0.01 mW / cm ^2, the production efficiency is deteriorated, without causing cure too fast structure formation of the photo-curable resin composition exceeds 100 mW / cm ² This is because there are cases where optical characteristics including the desired light diffusibility cannot be expressed.

  Although the irradiation time of the parallel rays by ultraviolet rays and / or visible rays is not particularly limited, it is 10 seconds to 180 seconds, more preferably 30 seconds to 120 seconds.

As described above, the anisotropic light diffusing layer of the present invention has a specific internal structure in the uncured resin composition layer by irradiating parallel rays of low-illuminance ultraviolet rays and / or visible rays for a relatively long time. It is obtained by being formed. For this reason, unreacted monomer components may remain by such parallel light irradiation alone, resulting in stickiness, which may cause problems in handling properties and durability. In such a case, the residual monomer can be polymerized and cured by additional irradiation with ultraviolet light having a high illuminance of 1000 mW / cm ² or more. The irradiation at this time is preferably performed not from the photomask surface but from the substrate surface side.

A method for obtaining a bent structure in the column axis direction of the plurality of louver rod structures of the anisotropic light diffusing layer of the present invention is not particularly limited, but light having a silicone skeleton is included in the photocurable resin composition. A method using a curable compound, a method obtained by giving a temperature distribution in the thickness direction of the uncured resin composition layer when the uncured resin composition layer is cured, and the like are effective. The methods can be combined as appropriate.
For example, in the case of the method obtained by giving the above temperature distribution, the surface of the base material which is the opposite side surface is cooled by applying cold air to the photomask surface on which parallel rays of ultraviolet rays and / or visible rays are incident. It is possible to generate a temperature distribution in the thickness direction perpendicular to the plane of the uncured resin composition layer by heating with a temperature control plate or the like. Since the refractive index of the photocurable resin composition changes depending on the temperature, the photocurable resin composition bends when the parallel rays of the irradiated ultraviolet rays and / or visible rays pass through the inside of the uncured resin composition layer. The bending angle, position, and direction of this bending can be adjusted by the refractive index of the photocurable resin composition, the reaction rate, the temperature gradient, the film thickness, the inclination of parallel rays, or the like.
Here, the reaction rate of the photocurable resin composition is appropriately adjusted according to the reactivity of the composition itself, the viscosity, the irradiation intensity of parallel rays by ultraviolet rays and / or visible rays, the type and amount of the photoinitiator, and the like. The

  Furthermore, the method for obtaining an inclined structure in the column axis direction of the plurality of louver rod structures of the anisotropic light diffusing layer of the present invention is not particularly limited. For example, the photocurable resin composition has a silicone skeleton. A method using a photocurable compound, a method obtained by inclining parallel rays by ultraviolet rays and / or visible rays, and the like are effective. These methods can be appropriately combined.

<Other layer lamination process>
It is an arbitrary step of laminating other layers on the anisotropic light diffusion layer obtained by the curing step depending on the application.
Depending on the application, the anisotropic optical film of the present invention can be obtained by laminating the above-mentioned other layers on the anisotropic light diffusion layer directly or via an adhesive layer or an adhesive layer.
The method is not limited, but the pressure-sensitive adhesive or adhesive application method for forming the pressure-sensitive adhesive layer or adhesive layer is not particularly limited when directly applying to the anisotropic light diffusion layer, and roll coating is not particularly limited. Known techniques including a method and a gravure coating method can be employed.
As another method, it may be applied directly to the other layers by the same method.
In addition, a method of laminating a sheet-like non-carrier type film in which an adhesive layer or an adhesive layer is previously sandwiched between separators having different peeling forces with a laminator is also possible.

≪Usage≫
The anisotropic optical film of the present invention can be used by being bonded to a desired place via an adhesive layer or an adhesive layer. For example, a liquid crystal display device (LCD), a plasma display panel (PDP), electroluminescence, etc. The present invention can be applied to a display device such as a display (ELD), a cathode ray tube display (CRT), a surface electric field display (SED), and electronic paper, and particularly preferably a transmissive type, a reflective type, or a transflective type. The liquid crystal display device (LCD) can be used.

  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 bulkhead with a thickness of 0.05 mm made of a photocurable resin composition using a PET film (product name: A4100, manufactured by Toyobo Co., Ltd., trade name: A4100) having a thickness of 100 μm and a size of 150 × 150 mm as a base material, using a dispenser around the entire periphery Formed. The height of the partition wall corresponds approximately to the thickness of the anisotropic light diffusion layer obtained. The partition wall is filled with a photocurable resin composition having the following composition to form an uncured resin composition layer, and then a glass substrate photomask made of a chromium film is formed on the surface of the uncured resin composition layer. (Thickness 2 mm) was laminated.
The photomask of the standard shown in FIG. 6 is used, the size is 5 inches × 5 inches, the pattern is divided into nine blocks, the pitch between each pattern is 0.85 cm, the outer periphery of the photomask and each pattern The distance from the outer periphery was 1 cm. FIG. 7 is a photograph of the appearance.
In addition, the standard pattern shown in FIG. 5 is used, and the size is 3 cm × 3 cm, and the substantially rounded rectangular shape has a long diameter line width Y of 1.5 μm, a parallel line width L of 0.9 μm, and a rounded radius width. r is 0.3 μm, the short-diameter line width S is 0.5 μm, the pitch between the substantially rounded rectangles in the long-diameter line width Y direction is 1.1 μm, and between the substantially rounded rectangles in the short-diameter line width S direction The pitch was 0.4 μm. FIG. 8 is a partial surface photograph thereof.
Silicone urethane acrylate (refractive index: 1.460, weight average molecular weight: 5,890) 20 parts by weight (trade name: 00-225 / TM18, manufactured by RAHN)
・ Neopentyl glycol diacrylate (refractive index: 1.450) 30 parts by weight (manufactured by Daicel-Cytec Co., Ltd., trade name: Ebecryl 145)
Bisphenol A EO adduct diacrylate (refractive index: 1.536) 15 parts by weight (manufactured by Daicel-Cytec Co., Ltd., 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)
Parallel rays (wavelength: emitted from an irradiation unit for incident light of a UV spot light source (trade name: L2859-01, manufactured by Hamamatsu Photonics Co., Ltd.) from the photomask surface on the uncured resin composition layer on which the photomask is laminated. 365 nm ultraviolet rays) was irradiated for 1 minute with an irradiation intensity of 5 mW / cm ² , and further, ultraviolet rays with an irradiation intensity of 20 mW / cm ² were irradiated from the substrate side to be completely cured. From there, the base material and the photomask were peeled off to obtain the anisotropic light diffusion layer (anisotropic optical film) of Example 1.

[Example 2]
After laminating a glass substrate photomask (thickness 2 mm) with a chromium film on the surface of the uncured resin composition layer, the uncured resin composition layer is placed on a hot plate heated to 80 ° C. The anisotropic light diffusion layer (anisotropic) of Example 2 is the same as Example 1, except that the air is sent from a blower and cooled and irradiated with parallel rays from the photomask side of the uncured resin composition layer. Optical film).
Further, when the thickness direction of the anisotropic light diffusion layer (direction perpendicular to the plane of the anisotropic light diffusion layer) was confirmed with an optical microscope, it had two diffusion center axes, and the thickness direction of the anisotropic light diffusion layer was 0 °. In this case, each diffusion center axis had a bent structure with inclinations of 0 ° and 15 ° and a bending angle of 15 °.

[Example 3]
A glass substrate photomask (thickness: 2 mm) made of a chromium film is laminated on the surface of the uncured resin composition layer, and then a parallel beam from the surface of the photomask on the uncured resin composition layer is normal to the photomask plane. An anisotropic light diffusing layer (anisotropic optical film) of Example 3 was obtained in the same manner as in Example 1 except that irradiation was performed with an inclination of 10 ° from the direction.
In addition, when the thickness direction of the anisotropic light diffusion layer (direction perpendicular to the plane of the anisotropic light diffusion layer) was confirmed with an optical microscope, a plurality of louver rod structures were inclined by about 10 ° with respect to the thickness direction. Had.

[Example 4]
The photomask pattern has a size of 3 cm × 3 cm and a substantially rounded rectangular shape with a long diameter line width (Y) of 1.5 μm, a parallel line width (L) of 1.1 μm, and a rounded radius width (r) of 0. 2 μm, the short diameter line width S is 0.5 μm, the pitch between the substantially rounded rectangles in the long diameter line width Y direction is 1.3 μm, and the pitch between the substantially rounded rectangles in the short diameter line width S direction is 0. An anisotropic light diffusion layer (anisotropic optical film) of Example 4 was obtained in the same manner as Example 1 except that the thickness was 0.4 μm.

[Comparative Example 1]
Implementation was carried out except that a PET film (product name: A4100, manufactured by Toyobo Co., Ltd.) having a thickness of 50 μm and a size of 150 × 150 mm was laminated on the surface of the uncured resin composition layer instead of a glass substrate photomask made of a chromium film. In the same manner as in Example 1, the anisotropic light diffusion layer (anisotropic optical film) of Comparative Example 1 was obtained.
In the anisotropic light diffusing layer of Comparative Example 1, a plurality of pillar structures are formed in the anisotropic light diffusing layer, not a plurality of louver rod structures, and a cross-sectional shape orthogonal to the column axis direction of the plurality of pillar structures is When confirmed with an optical microscope, it was substantially circular.

[Comparative Example 2]
The photomask pattern has a size of 3 cm × 3 cm and a substantially rounded rectangular shape with a long diameter line width (Y) of 1.5 μm, a parallel line width (L) of 1.3 μm, and a rounded radius width (r) of 0. 1 μm, the short-diameter line width S is 0.5 μm, the pitch between the substantially rounded rectangles in the long-diameter line width Y direction is 1.5 μm, and the pitch between the substantially rounded rectangles in the short-diameter line width S direction is 0 An anisotropic light diffusion layer (anisotropic optical film) of Comparative Example 2 was obtained in the same manner as in Example 1 except that the thickness was 0.4 μm.

[Comparative Example 3]
The photomask pattern has a size of 3 cm × 3 cm and a substantially rounded rectangular shape with a major diameter line width (Y) of 1.5 μm, a parallel line width (L) of 0.5 μm, and a rounded corner radius width (r) of 0. 5 μm, the short diameter line width S is 0.5 μm, the pitch between the substantially rounded rectangles in the long diameter line width Y direction is 0.8 μm, and the pitch between the substantially rounded rectangles in the short diameter line width S direction is 0. An anisotropic light diffusion layer (anisotropic optical film) of Comparative Example 3 was obtained in the same manner as in Example 1 except that the thickness was 0.4 μm.

"Evaluation method"
The anisotropic light diffusion layers (anisotropic optical films) of Examples and Comparative Examples produced as described above were evaluated as follows.

<Surface observation of anisotropic light diffusion layer (anisotropic optical film)>
The surface of the anisotropic light diffusing layer (anisotropic optical film) of Examples and Comparative Examples (irradiation side at the time of parallel light irradiation) was observed with an optical microscope, and the major diameter line width (Y) and parallel lines of a substantially rounded rectangle The width (L) and the rounded radius width (r) were measured. The width was an average value obtained by measuring 100 arbitrary rounded rectangles.

<Thickness of anisotropic light diffusion layer (anisotropic optical film)>
The thicknesses of the anisotropic light diffusion layers (anisotropic optical films) in the examples and comparative examples were evaluated using a micrometer. At the time of measurement, the measurement was performed such that the surface shape was not crushed. The measured value is an average value of the measured values of a total of five locations including the vicinity of the four corners of the plane of the anisotropic light diffusion layer (anisotropic optical film) and one location near the center of the plane. Thickness.

<Linear transmittance and diffusion width of anisotropic light diffusion layer (anisotropic optical film)>
Using a variable angle photometer goniophotometer (manufactured by Genesia Co., Ltd.) that can arbitrarily change the light projecting angle of the light source and the light receiving angle of the detector as shown in FIG. The optical properties of (anisotropic optical film) were evaluated. The detector 5 was fixed at a position where it received straight light from the light source 4, and the anisotropic light diffusion layer (anisotropic optical film) 10 obtained in the examples and comparative examples was set in the sample holder therebetween. As shown in FIG. 3, the anisotropic light diffusing layer 10 is rotated around the rotation axis P of the anisotropic light diffusing layer 10 (the direction of which coincides with the line AA of the anisotropic light diffusing layer shown in FIG. 1A). The amount of linear transmitted light and the linear transmittance corresponding to each incident light angle at the rotational position of each anisotropic light diffusion layer 10 were measured by the detector 5. With this evaluation method, it is possible to evaluate at which incident light angle the incident light is diffused. The linear transmitted light amount was measured with respect to the wavelength in the visible light region using a visibility filter.
An optical profile was obtained from the obtained data, and the maximum linear transmittance and the minimum linear transmittance were obtained from this optical profile.
Further, the width of the incident light angle range between the two incident light angle values with respect to the linear transmittance that is an intermediate value between the maximum linear transmittance and the minimum linear transmittance determined in the optical profile (the two in the optical profile) The inside of the incident light angle) was determined and used as the diffusion width.

<Glare of anisotropic light diffusion layer (anisotropic optical film)>
A light reflection layer is provided in the lower layer of the anisotropic light diffusion layer (anisotropic optical film) of Examples and Comparative Examples, light is incident on the anisotropic light diffusion layer, and the glare of the reflected light is visually confirmed, When glare was not confirmed, it evaluated as (circle), and when glare was confirmed, it evaluated as x.

<Abrupt change in luminance of anisotropic light diffusion layer (anisotropic optical film)>
As an evaluation of a sudden change in luminance, incident light having a maximum linear transmittance F _A (%) in the graph (optical profile) shown in FIG. When the linear transmittance suddenly changes between the angle A (°) and the incident light angle B (°) that takes the minimum linear transmittance F _B (%), the luminance also suddenly changes. , The change in linear transmittance with respect to the change in incident light angle, that is, the slopes are determined for F _A and A and F _B and B, and if the slopes are steep, there is a sharp change in brightness; If the slope was gentle, it was judged that there was no sudden change in luminance.
Specifically, when the slope is α, α is (F _A −F _B ) / | A−B |, and if α is α ≧ 1.5, there is a sharp change in luminance. X, and if α <1.5, the change in luminance was gradual and there was no sense of incongruity.
In addition, as shown in FIG. 9, in each of the two types of maximum linear transmittance (F _A1 and F _A2 ) and minimum linear transmittance (F _B1 and F _B2 ), slopes α ₁ and α _{2 represented by} the following formulas Of these, the above determination was made on the value with the larger inclination.
α ₁ : (F _A1 -F _B1 ) / | A ₁ -B ₁ |
α ₂ : (F _A2 -F _B2 ) / | A ₂ -B ₂ |

The above evaluation was performed and the evaluation results are summarized in Table 1.

As shown in the above results, the anisotropic light diffusion layers (anisotropic optical films) of Examples 1 to 4 have good maximum linear transmittance, minimum linear transmittance, diffusion width, glare, and rapid change in luminance. In particular, Examples 2 and 3 gave better results. This is because, in the anisotropic light diffusion layer of the anisotropic optical film, the shape of the cross section perpendicular to the column axis direction (thickness direction of the anisotropic light diffusion layer) of the plurality of louver rod structures is optimized. By adopting a rectangular shape, the lens effect that moderately diffuses the light emitted from the anisotropic light diffusing layer is manifested, suppressing glare and sudden changes in brightness due to light interference, and optimizing the balance of optical properties including light diffusivity It is thought that it was possible.
Furthermore, since the anisotropic light-diffusion layers of the present invention in Examples 1 to 4 were within the range of the rounded radius width defined above, the diffusion width could be widened.
The reason why the diffusion width of Example 3 is large is considered to be that the louver rod structure was appropriately inclined, and the reason why the diffusion width of Example 2 was the largest was that the louver rod structure. This is because the region in which light is strongly diffused can be further widened and the diffusion width can be further increased.

On the other hand, since the anisotropic light diffusion layer (anisotropic optical film) of Comparative Example 1 uses a PET film instead of a photomask, a plurality of pillar structures are formed, and the pillar axes of the plurality of pillar structures are formed. The shape of the cross section perpendicular to the direction was not a substantially rounded rectangle but a substantially circular shape, and the maximum linear transmittance and the diffusion width were inferior to those of the present invention.
Moreover, since the comparative example 2 is not the optimized substantially rounded rectangle, the result of the rapid change of the minimum linear transmittance, the diffusion width, the glare, and the brightness was inferior to that of the present invention.
And since the comparative example 3 is not an optimized substantially rounded rectangle, the maximum linear transmittance was inferior to that of the present invention.

  As described above, since the anisotropic optical film of the present invention suppresses glare and abrupt changes in luminance and the balance of optical characteristics including light diffusivity is optimized, the anisotropic optical film can be used in various display devices. It can be used.

1 Anisotropic light diffusion layer (anisotropic optical film)
2 Louver rod structure 3 Matrix region 4 Light source 5 Detector 10 Anisotropic light diffusion layer (anisotropic optical film or sample)
Y major line width L parallel line width r rounded radius width S minor diameter line width T anisotropic light diffusion layer thickness

Claims (4)

An anisotropic optical film in which the amount of transmitted light changes depending on the incident light angle of light,
The anisotropic optical film has at least one anisotropic light diffusion layer,
The anisotropic light diffusion layer is
A plurality of louver rod structures and a matrix region;
An anisotropic optical film, wherein a cross-sectional shape perpendicular to the column axis direction of the louver rod structure is a substantially rounded rectangle in which both ends of two substantially parallel lines are connected by a substantially arc.   When the parallel line width of the two substantially parallel lines is L, the long diameter line width of the substantially long diameter line which is the maximum width of the substantially rounded rectangle is Y, and (Y−L) / 2 is r, Equation 2r The anisotropic optical film according to claim 1, wherein <L <10r is satisfied.   The anisotropic optical film according to claim 1 or 2, wherein the anisotropic light diffusion layer has a thickness in the range of 10 µm to 100 µm.   The anisotropic optical film according to any one of claims 1 to 3, wherein the length of r is in a range of 0.01 µm or more and less than 0.4 µm.