阅读说明：本技术 使用各向异性光学膜的反射型显示装置 (Reflection type display device using anisotropic optical film ) 是由 坂野翼 杉山仁英 于 2020-03-26 设计创作，主要内容包括：提供一种没有刺眼、模糊感、白显示时能够显示高品质的纸那样的白色的、白色呈色优异的(具有充分的纸白感的)反射型显示装置。一种反射型显示装置,其特征在于,其为具备反射板和直线透射率根据入射光角度而变化的各向异性光学膜的反射型显示装置,上述各向异性光学膜配置在比上述反射板更靠近视觉识别侧,上述各向异性光学膜至少包含各向异性光扩散层,上述各向异性光扩散层具有基质区域和折射率与上述基质区域不同的多个柱状区域,上述多个柱状区域从上述各向异性光扩散层的一个表面向另一表面取向而构成,作为上述各向异性光扩散层的一个表面的上述多个柱状区域的平均长径/平均短径的纵横比为20以下。(Provided is a reflection type display device which has no glare, gives a blurred feeling, and can display a white color such as a high-quality paper when displaying a white color, and has an excellent white color appearance (has a sufficient paper-white feeling). A reflective display device comprising a reflective plate and an anisotropic optical film whose linear transmittance changes according to an incident light angle, wherein the anisotropic optical film is disposed on a viewing side of the reflective plate, the anisotropic optical film comprises at least an anisotropic light diffusion layer, the anisotropic light diffusion layer has a matrix region and a plurality of columnar regions having a refractive index different from that of the matrix region, the plurality of columnar regions are formed by being oriented from one surface of the anisotropic light diffusion layer to the other surface, and the aspect ratio of the average major axis to the average minor axis of the plurality of columnar regions as one surface of the anisotropic light diffusion layer is 20 or less.)

1. A reflection type display device is characterized in that,

which is a reflection type display device comprising a reflection plate and an anisotropic optical film whose linear transmittance changes according to the incident light angle,

the anisotropic optical film is disposed on a visual recognition side of the reflective plate,

the anisotropic optical film comprises at least an anisotropic light diffusion layer,

the anisotropic light diffusion layer has a matrix region and a plurality of columnar regions having a refractive index different from that of the matrix region,

the plurality of columnar regions are constituted by being oriented from one surface to the other surface of the anisotropic light diffusion layer,

an aspect ratio of an average major axis/an average minor axis of the plurality of columnar regions on one surface of the anisotropic light diffusion layer is 20 or less.

2. Reflective display apparatus of claim 1, wherein said anisotropic light diffusion layer has a haze value of 50% to 90%.

3. Reflective display apparatus of claim 1 or 2,

the anisotropic light diffusion layer has at least 1 scattering central axis,

a scattering center axis angle, which is an angle between a normal direction of one surface of the anisotropic light diffusion layer and the at least 1 scattering center axis, is-30 ° to +30 °.

4. Reflective display device according to any one of claims 1 to 3, wherein the maximum in-line transmittance of said anisotropic light diffusion layer is 10% to 60%.

5. Reflective display device according to any one of claims 1 to 4, wherein said anisotropic light diffusion layer has a thickness of 10 μm to 100 μm.

6. A reflective display device according to any one of claims 1 to 5, wherein said aspect ratio is 5 or less.

Technical Field

The present invention relates to a reflective display device using an anisotropic optical film.

Background

In a conventional liquid crystal display device such as a TN (Twisted Nematic) liquid crystal display, two polarizing plates on both surfaces of a liquid crystal cell are arranged so that their polarization planes are orthogonal to each other. Thus, for example, in the normally black mode, the liquid crystal cell operates in such a manner that light passing through one polarizing plate is polarized by the liquid crystal and passes through the other polarizing plate when in the driven state, forming a white screen, and operates in such a manner that light does not pass through the other polarizing plate when in the non-driven state, forming a black screen. Since light passes through the polarizing plate as described above, light having a direction different from the polarizing plane of the polarizing plate cannot pass through the polarizing plate, and the amount of used liquid crystal is small, which makes it easy to form a dark display device.

In recent years, due to the spread of mobile terminals and wearable devices, the chance of using a display device outdoors is increasing. In order to cope with this situation, there are increasing reflective liquid crystal display devices that obtain a light source by capturing and reflecting outdoor external light.

On the other hand, since the reflection type liquid crystal display device cannot adjust the spectrum of the light source as in the transmission type liquid crystal display device, the wavelength characteristic of the polarizing plate directly forms a display color, and thus improvement of the wavelength characteristic of the polarizing plate becomes an important subject. In the conventional reflective liquid crystal display device, white display tends to be yellowish, and black display tends to be bluish. Therefore, the display quality is considered to be inferior to that of other reflective display devices (electronic paper displays and the like).

Here, patent document 1 proposes the following invention: when the reflective liquid crystal display device comprises a reflector, a liquid crystal cell, a phase difference plate and a base material (A) having a polarizing function in this order from the back side, an anisotropic light diffusion plate having a polarizing function is provided at any position among the reflector and the liquid crystal cell, the liquid crystal cell and the phase difference plate, and the phase difference plate and the base material (A) having a polarizing function, so that the hue caused by the problem of yellow color in white display and blue color in black display of the polarizer is improved.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2015/111472

Disclosure of Invention

Problems to be solved by the invention

Regarding the anisotropic light diffusion plate used in patent document 1, there is a document "the anisotropic light diffusion as described in japanese patent laid-open No. 2012-37611 has a polarization function due to the anisotropic light diffusion, and therefore can be used as a reflective polarizing plate", and in the anisotropic light diffusion layer in japanese patent laid-open No. 2012-37611, a plurality of layers having different refractive indices are formed in a plane parallel to the film surface as stripes arranged in one direction. Hereinafter, in the present invention, such a plate-like structure as one layer is referred to as a louver structure.

The optical characteristics of the louver structure are good in light transmittance, but the louver structure has a problem of glare, and patent document 1 cannot confirm a description of the problem when the louver structure is used in a reflective liquid crystal display device.

On the other hand, the sharpness of image display, so-called blur suppression, is also an important display characteristic element, and a reflective display device that suppresses both glare and blur is desired.

Accordingly, an object of the present invention is to provide a reflective display device which is free from the above-mentioned glare and blur and can display a white color such as a high-quality paper when displaying a white color, and which is excellent in white color rendering (has a sufficient paper-white feeling).

Means for solving the problems

In order to solve the above problems, a reflective display device according to the present invention is a reflective display device including a reflective plate and an anisotropic optical film whose linear transmittance changes according to an incident light angle, wherein the anisotropic optical film includes at least an anisotropic light diffusion layer, the anisotropic light diffusion layer includes a matrix region and a plurality of columnar regions having a refractive index different from that of the matrix region, the plurality of columnar regions are oriented from one surface of the anisotropic light diffusion layer to the other surface, and an aspect ratio of an average major axis to an average minor axis of the plurality of columnar regions on the one surface of the anisotropic light diffusion layer is 20 or less.

Effects of the invention

According to the present invention, by setting the aspect ratio of the plurality of columnar regions on the one surface of the anisotropic light diffusion layer of the anisotropic optical film to a specific value, when the anisotropic optical film is provided on the visual recognition side of the reflective display device compared to the reflective plate, it is possible to provide a reflective display device having a sufficient paper-white feeling with less glare and less blurring.

Drawings

Fig. 1 is a schematic view illustrating an example of arrangement of a reflection plate and an anisotropic optical film in a reflection type display device of the present invention.

Fig. 2 is an explanatory view showing the incident angle dependence of the anisotropic optical film according to the present invention.

Fig. 3 is a surface view in a plane direction of an anisotropic light diffusion layer according to the present invention.

Fig. 4 is a schematic view of an anisotropic light diffusion layer according to the present invention and an example of a transmitted light diagram.

Fig. 5 is a three-dimensional polar display for explaining the scattering center axis P of the anisotropic light diffusion layer.

Fig. 6 is an example of optical contour lines for explaining the diffusion regions and the non-diffusion regions of the anisotropic light diffusion layer.

FIG. 7 is a schematic view showing a method for measuring the incident light angle dependence of the anisotropic light diffusion layer.

Fig. 8 is a schematic view showing a method of manufacturing an anisotropic light diffusion layer to which the present invention relates by optional processes 1 to 3.

Fig. 9 is a photograph of an image of the reflective display device of example 1 and comparative example 2.

Detailed Description

1. Definition of the main terms

Here, main terms are defined with respect to the anisotropic optical film (anisotropic light diffusion layer).

The term "anisotropic optical film" includes a case where the anisotropic light diffusion layer is a single layer (only one layer), a case where 2 or more layers of the anisotropic light diffusion layer are stacked (in this case, the layers of the anisotropic light diffusion layer may be stacked with an adhesive layer or the like interposed therebetween), and the like. Thus, for example, when the anisotropic light diffusion layer is a single layer, it means that the single-layer anisotropic light diffusion layer is an anisotropic optical film.

The "anisotropic optical film" has a light diffusion, transmission, and diffusion distribution having an incident light angle-dependent anisotropy and directivity that vary according to the incident angle of light (details are described below). Therefore, the present invention is different from a directional diffusion film, an isotropic diffusion film, and a diffusion film oriented in a specific direction, which have no incident light angle dependency.

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 according to the present invention, and indicate whether the refractive index is lower or higher than the other, and are opposite to each other. These regions are formed when the material forming the anisotropic optical film is cured.

The "scattering center axis" means a direction in which, when the angle of incident light to the anisotropic optical film or the anisotropic light diffusion layer changes, the linear transmittance coincides with the incident light angle of light having near symmetry with the incident light angle as a boundary. The reason why "near symmetry" is assumed is that the optical characteristics (hereinafter referred to as "optical profile (optical プロファイル)") do not have strict symmetry when the scattering center axis is inclined with respect to the normal direction of the film. The scattering center axis can be determined by observing the inclination angle of the columnar region in the cross section of the anisotropic optical film with an optical microscope, and observing the projection shape of light through the anisotropic optical film by changing the incident light angle.

The "scattering center axis angle" is an inclination angle of a scattering center axis with respect to a normal direction of a principal plane surface of the anisotropic optical film or the anisotropic light diffusion layer, and is an angle when the normal direction of the anisotropic optical film or the anisotropic light diffusion layer is 0 °.

In general, the "linear transmittance" is a ratio of a "linear transmitted light amount" which is a transmitted light amount in the same linear direction as the incident direction to an "incident light amount" which is a light amount of the incident light when the light is incident from a certain incident light angle with respect to the linear transmittance of the light incident on the anisotropic optical film or the anisotropic light diffusion layer, and is expressed by the following equation.

Linear transmittance (%) (linear transmission light amount/incident light amount) × 100

In the present invention, the "scattering" and the "diffusion" are not distinguished from each other in use, and both of them have the same meaning. Further, "photopolymerization" and "photocuring" mean that a photopolymerizable compound undergoes a polymerization reaction by light, and both are used as synonyms.

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and the drawings, components denoted by the same reference numerals have substantially the same structure and function.

2. Reflective display device

A reflection type display device of the present invention includes a reflection plate and an anisotropic optical film whose linear transmittance changes according to an incident light angle.

Fig. 1 is a schematic view illustrating an example of arrangement of a reflective plate and an anisotropic optical film in a reflective display device according to the present invention, and is an example of an inner surface reflection type and an outer surface reflection type of a reflective liquid crystal display device.

In the reflective liquid crystal display devices 100 and 101, there are a "inner surface reflection type" in which the metal electrode 130 as a scattering reflective plate is provided on the back glass 120 side of the liquid crystal layer 110, and a "outer surface reflection type" in which the back reflective plate 180 is provided outside the back retardation film 160 and the back polarizing plate 140.

Although this is the arrangement position of the reflection plate and the anisotropic optical film in the reflection-type display device of the present invention, the position of the anisotropic optical film does not matter as long as it is closer to the external light incidence surface side of the reflection-type display device (the side for visual recognition by a visual recognizer, the side for visual recognition of reflected light) than the reflection plate. For example, in fig. 1, an anisotropic optical film 150 is provided between the front glass 121 and the front retardation film 161 (which is located inside the front polarizing plate 141) via adhesive layers 170 and 171.

The adhesive used for the adhesive layers 170 and 171 is not particularly limited as long as it has transparency, and an adhesive having pressure-sensitive adhesiveness at room temperature is preferably used. Examples of such a binder include resins such as polyester resins, epoxy resins, polyurethane resins, silicone resins, and acrylic resins. Acrylic resins are particularly preferred because they are optically transparent and relatively inexpensive.

The reflective plate according to the present invention is a member that reflects light, such as a reflective film, a reflective plate, or a metal electrode, and can be a member provided in a conventionally used reflective display device.

2-1. Anisotropic optical film

The linear transmittance of the anisotropic optical film according to the present invention varies depending on the incident light angle of the incident light. That is, incident light in a predetermined angle range is transmitted while maintaining linearity, and incident light in other angle ranges exhibits diffusibility.

Fig. 2 is an explanatory view showing the incident angle dependence of the anisotropic optical film according to the present invention.

It is shown that the anisotropic optical film of fig. 2 shows diffusibility at an incident light angle of 20 ° to 50 °, and shows linear transmittance without displaying diffusibility at other angles. That is, as shown in the figure, the diffusivity is not shown at 0 ° smaller than 20 ° and 65 ° larger than 50 °, but the linear transmittance is shown.

The anisotropic optical film of the present invention includes at least one or more anisotropic light diffusion layers. The anisotropic light diffusion layer included in the anisotropic optical film may include a plurality of anisotropic light diffusion layers having different optical characteristics such as linear transmittance, haze value, and scattering center axis.

Here, the multilayer anisotropic light diffusion layer is formed by laminating a plurality of single-layer anisotropic light diffusion layers directly or via an adhesive layer. As the adhesive used in the adhesive layer, the adhesive mentioned in the description of fig. 1 above can be used.

On the other hand, when the anisotropic light diffusion layer is directly laminated on the anisotropic light diffusion layer, the optical film can be produced by the following method: after a single-layer anisotropic light diffusion layer is formed by curing a composition layer containing a photopolymerizable compound, a coating material containing a photopolymerizable compound is directly applied to the single-layer anisotropic light diffusion layer in a sheet form to form a composition layer, and then the composition layer is cured.

Further, the anisotropic optical film may be formed by laminating a plurality of layers in addition to the anisotropic light diffusion layer.

Examples of the anisotropic optical film in which a plurality of layers are laminated include a film in which a layer having another function is laminated in the anisotropic optical film. The anisotropic optical film according to the present invention may be used by being laminated on a transparent substrate such as a glass substrate.

The anisotropic optical film of the present invention is preferably a single-layer anisotropic light diffusion layer from the viewpoint of ease of production and cost.

The thickness of the anisotropic optical film is preferably 10 to 500 μm, and more preferably 50 to 150 μm in consideration of the use and productivity.

The anisotropic light diffusion layer according to the present invention has a matrix region and a plurality of columnar regions having a refractive index different from that of the matrix region, and has anisotropy and directivity in which incident light angle dependency exists.

The anisotropic light diffusion layer is usually composed of a cured product of a composition containing a photopolymerizable compound. Therefore, the matrix region and the plurality of columnar regions are formed of the same composition and are formed separately.

Here, the difference in refractive index is not particularly limited as long as at least a part of light incident on the anisotropic light diffusion layer is reflected at the interface with the matrix region and the interface with the columnar region to a different degree, and for example, the difference in refractive index between the matrix region and the columnar region may be 0.001 or more.

The thickness of the anisotropic light diffusion layer according to the present invention (the length in the direction perpendicular to the principal plane of the anisotropic light diffusion layer and the same direction as the thickness of the anisotropic optical film) is not particularly limited, and is, for example, preferably 1 μm to 200 μm, and more preferably 10 μm to 100 μm. When the thickness exceeds 200 μm, not only a large amount of material cost is required, but also the cost involved in UV irradiation increases, and therefore, not only the manufacturing cost increases, but also image blur and contrast deterioration are liable to occur due to an increase in the diffusion property of the anisotropic light diffusion layer in the thickness direction. When the thickness is less than 1 μm, it may be difficult to achieve sufficient light diffusibility and light-condensing property.

The anisotropic light diffusion layer according to the present invention comprises a plurality of columnar regions that are generally oriented and extend from one surface of the anisotropic light diffusion layer to the other surface.

The surface shape of the plurality of columnar regions on the surface of the anisotropic light diffusion layer (the surface of the principal plane of the anisotropic light diffusion layer) according to the present invention may have a short diameter and a long diameter.

The surface shape is not particularly limited, and may be, for example, circular, elliptical, or polygonal. When the shape is circular, the short diameter is equal to the long diameter; when the shape is an ellipse, the short diameter is the length of the short axis, and the long diameter is the length of the long axis; in the case of a polygon, the shortest length that can be considered when drawing a straight line in the polygon may be defined as the minor axis, and the longest length may be defined as the major axis.

Fig. 3 is a surface view in a plane direction of the anisotropic light diffusion layer according to the present invention, showing a plurality of columnar regions (202 and 212) and matrix regions (201 and 211) observed from the surface of the anisotropic light diffusion layer 200, 250. In the figure, LA represents a long diameter and SA represents a short diameter.

The surface of the anisotropic light diffusion layer was observed with an optical microscope, and the short diameter and the long diameter were measured for each of 20 arbitrarily selected columnar regions, and the average values thereof were set as the short diameter and the long diameter according to the present invention.

The average value of the short diameters (average short diameter) of the plurality of columnar regions is preferably 0.5 μm or more, more preferably 1.0 μm or more, and still more preferably 1.5 μm or more. On the other hand, the average value of the short diameters of the plurality of columnar regions is preferably 5.0 μm or less, more preferably 4.0 μm or less, and still more preferably 3.0 μm or less. The lower limit value and the upper limit value of the minor axis of these plural columnar regions may be appropriately combined.

The average value of the major axes (average major axis) of the plurality of columnar regions is preferably 0.5 μm or more, more preferably 1.0 μm or more, and still more preferably 1.5 μm or more. On the other hand, the average of the major axes of the plurality of columnar regions is preferably 100 μm or less, more preferably 50 μm or less, and still more preferably 30 μm or less. The lower limit value and the upper limit value of the minor axis of these plural columnar regions may be appropriately combined.

The aspect ratio, which is the ratio of the average major axis to the average minor axis (average major axis/average minor axis) of the plurality of columnar regions according to the present invention, is 20 or less. Fig. 3(a) shows an anisotropic light diffusion layer having an aspect ratio of less than 2, and fig. 3(b) shows an anisotropic light diffusion layer having an aspect ratio of 2 to 20.

The upper limit of the aspect ratio is preferably 20, and more preferably 5 or less. When the aspect ratio is within this range, an effect of suppressing glare can be obtained.

Fig. 4 is a schematic view of an anisotropic light diffusion layer according to the present invention and an example of a transmitted light diagram.

When the aspect ratio of the anisotropic light diffusion layer of the present invention is 1 or more and less than 2, the transmitted light is isotropically diffused when light parallel to the axial direction of the plurality of columnar regions is irradiated (see fig. 4 (a)). On the other hand, when the aspect ratio is 2 to 20, when light parallel to the axial direction is irradiated in the same manner, the light is diffused with anisotropy corresponding to the aspect ratio (see fig. 4 (b)).

The anisotropic light diffusion layer according to the present invention may include a plurality of columnar regions having an aspect ratio of 1, or may include a plurality of columnar regions having different aspect ratios.

The anisotropic light diffusion layer according to the present invention may have at least 1 scattering center axis.

The orientation direction (extending direction) from one surface to the other surface of the columnar region may be formed parallel to the scattering center axis, and may be appropriately determined so that the anisotropic light diffusion layer has desired linear transmittance and diffusivity. Note that, as long as the scattering center axis is parallel to the orientation direction of the columnar region, it is sufficient to satisfy the law of refraction (Snell's law), and it is not necessarily strictly parallel.

Snell's law is that light has a refractive index n₁Has a medium refractive index n₂When the medium is incident on the interface, the incident light angle theta is₁Angle of refraction theta₂Is established by n₁sinθ₁＝n₂sinθ₂The relationship (2) of (c). For example if set to n₁1 (air), n₂When the incident light angle is 30 °, the orientation direction (refraction angle) of the columnar region is about 19 °, and if the incident light angle and the refraction angle are different even in this way, the present invention is included in the concept of parallelism as long as Snell's law is satisfied.

As described above, the scattering center axis means a direction in which the light diffusion property coincides with the incident light angle of light having near symmetry with the incident light angle as a boundary when the incident light angle to the anisotropic light diffusion layer is changed. The incident light angle in this case is substantially the center portion (the center portion of the region called the diffusion region) between the minimum linear transmittance minimum values in the optical profile (for example, fig. 6) obtained by measuring the linear transmittance of the incident light angle through the anisotropic light diffusion layer.

Next, referring to fig. 5, the scattering center axis P of the anisotropic light diffusion layer will be described. Fig. 5 is a three-dimensional polar display for explaining the scattering center axis P of the anisotropic light diffusion layer.

According to the three-dimensional polar coordinate display as shown in fig. 5, if the main plane of the anisotropic light diffusion layer is taken as the xy plane and the normal line to the main plane is taken as the z axis, the central scattering axis P can be represented by the polar angle θ and the azimuth angleTo indicate. That is, Pxy in fig. 5 may be considered to be a longitudinal direction of a scattering center axis projected on the principal plane surface of the above-described anisotropic light diffusion layer.

Here, a polar angle θ (-90 ° < θ < 90 °) formed by a normal line (z axis shown in fig. 5) of the anisotropic light diffusion layer and an orientation direction (scattering center axis direction) of the columnar region is defined as a scattering center axis angle in the present invention. The axial angle of the columnar regions can be adjusted to a desired angle by changing the direction of light irradiated to the sheet-like photopolymerizable compound-containing composition when producing them.

The scattering center axis angle is not particularly limited, and is, for example, preferably from-30 ° to +30 °, and more preferably from-20 ° to +20 °. If the angle is out of the range of-30 ° to +30 °, visibility may be degraded, and a sufficient paper-white feeling may not be obtained.

When the plurality of anisotropic light diffusion layers have the same scattering center axis, the total number of the anisotropic light diffusion layers has 1 scattering center axis.

In addition, when the anisotropic light diffusion layer according to the present invention includes a plurality of scattering center axes, the anisotropic light diffusion layer includes a plurality of columnar regions having orientation directions parallel to the plurality of scattering center axes, respectively.

The length of the columnar region in the orientation direction according to the present invention is not particularly limited, and may be a length that penetrates from one surface to the other surface of the anisotropic light diffusion layer, or a length that starts from one surface but does not reach the other surface. The length of the columnar region in the orientation direction is preferably longer than the average length, because the light transmittance of the anisotropic light diffusion layer can be improved.

Fig. 6 is an example of optical contour lines for explaining the diffusion regions and the non-diffusion regions of the anisotropic light diffusion layer.

As described above, the anisotropic light diffusion layer has the incident light angle dependency of the light diffusibility in which the linear transmittance changes depending on the incident light angle. Hereinafter, a curve showing the incident light angle dependence of the light diffusibility as shown in fig. 6 will be referred to as an "optical profile".

FIG. 7 is a schematic view showing a method for measuring the incident light angle dependence of the anisotropic light diffusion layer. As shown in fig. 7, for the optical profile, an anisotropic light diffusion layer (or an anisotropic optical film composed of only a single layer of the anisotropic light diffusion layer) 200 or 250 as a sample is disposed between the light source 1 and the detector 2. In this embodiment, when the irradiation light I from the light source 1 is incident from the normal direction of the sample principal plane, the incident light angle is 0 °. The sample is arranged to be arbitrarily rotatable around a straight line V passing through the sample, and the light source 1 and the detector 2 are fixed. That is, according to this method, it can be obtained by: the sample is disposed between the light source 1 and the detector 2, and while changing the angle with the straight line V as the center axis, the amount of straight-line transmitted light that has passed straight through the sample and entered the detector 2 is measured, and the straight-line transmittance is calculated.

The optical contour line does not directly indicate light diffusibility, but if it is explained that the diffusibility increases conversely when the linear transmittance decreases, it can be said that the optical contour line indicates light diffusibility in general.

In a typical isotropic light diffusion film, a mountain-shaped optical profile having a peak at an incident light angle of about 0 ° is shown.

In the anisotropic light diffusion layer, for example, in the anisotropic light diffusion layer having a scattering center axis angle of 0 ° (fig. 6), a valley-shaped optical profile is shown in which the linear transmittance is small at an incident light angle in the vicinity of 0 ° (from-20 ° to +20 °), and the linear transmittance increases as (the absolute value of) the incident light angle increases.

In this way, the anisotropic light diffusion layer has the following properties: incident light is strongly diffused in an incident light angle range close to the scattering center axis, and in the above incident light angle range, the diffusivity is weak and the linear transmittance is high.

Hereinafter, as shown in fig. 6, the angular range of 2 incident light angles corresponding to the median linear transmittance between the maximum linear transmittance, which is the linear transmittance with the maximum linear transmittance among the incident light angles, and the minimum linear transmittance, which is the linear transmittance with the minimum linear transmittance among the incident light angles, is referred to as a diffusion region (the width of the diffusion region is referred to as a "diffusion width"), and the other incident light angular ranges are referred to as non-diffusion regions (transmission regions).

The maximum linear transmittance of light incident from the normal direction of the anisotropic light diffusion layer of the present invention is not particularly limited, and is, for example, preferably 10% to 60%, more preferably 10% to 50% when the anisotropic light diffusion layer included in the anisotropic optical film is 1 layer. By setting the range, a reflective display device having a sufficient paper-white feeling with less blur can be obtained.

The haze value of the anisotropic light diffusion layer of the present invention is an index indicating the diffusivity of the anisotropic light diffusion layer. If the haze value becomes large, the diffusibility of the anisotropic light diffusion layer increases. The haze value of the anisotropic light diffusion layer is not particularly limited, and is, for example, preferably 50% to 90%, more preferably 60% to 80%. By setting the range, a reflective display device having a sufficient paper-white feeling with less blur can be obtained.

When the anisotropic light diffusion layer included in the anisotropic optical film is a plurality of layers, the haze value of the total anisotropic light diffusion layer becomes the haze value of the anisotropic light diffusion layer of the anisotropic optical film.

The method for measuring the haze value of the anisotropic light diffusion layer is not particularly limited, and the haze value can be measured by a known method. For example, it can be measured by JIS K7136-1:2000 "method for calculating haze of plastic-transparent Material".

The anisotropic light diffusion layer according to the present invention may have irregularities on at least one surface of the anisotropic light diffusion layer. In this case, the arithmetic average roughness Ra of the surface of the anisotropic light diffusion layer is preferably 0.10 μm or less. The arithmetic average roughness Ra is determined in accordance with JIS B0601-2001.

The arithmetic average roughness Ra of the surface of the anisotropic light diffusion layer can be measured by a known method, and is not particularly limited. Examples thereof include a non-contact method using a confocal laser microscope and the like, and a contact method using a surface roughness measuring instrument using a probe and the like.

2-2. method for producing anisotropic light diffusion layer in anisotropic optical film

The method for producing the anisotropic light diffusion layer in the anisotropic optical film of the present invention can be produced by irradiating the uncured resin composition layer with light such as UV (ultraviolet) light. Hereinafter, the raw material of the anisotropic light diffusion layer will be described, and the manufacturing process will be described. Hereinafter, the production of an anisotropic optical film including 1 anisotropic light diffusion layer as a preferred example will be mainly described, and other modes will be supplemented as necessary.

2-2-1. raw material for anisotropic light diffusion layer

The raw materials of the anisotropic light diffusion layer are described in the order of (1) the photopolymerizable compound, (2) the photoinitiator, and (3) other optional components.

2-2-1-1 photopolymerisable compounds

The photopolymerizable compound used as a material for forming the anisotropic light diffusion layer according to the present invention is a material which is composed of a photopolymerizable compound (selected from macromonomers, polymers, oligomers, and monomers having a radical polymerizable or cationic polymerizable functional group) and a photoinitiator, and is polymerized and cured by irradiation with ultraviolet rays and/or visible light. Here, even if 1 kind of material is used to form the anisotropic light diffusion layer included in the anisotropic optical film, a difference in refractive index occurs by a difference in density. Because: the portion where the UV irradiation intensity is strong is cured at a high speed, and thus the polymerized and cured material moves around the cured region, and as a result, a region where the refractive index is high and a region where the refractive index is low are formed. It should be noted that the term (meth) acrylate means either acrylate or methacrylate.

Examples of the radical polymerizable compound having 1 or more unsaturated double bonds in the main molecule include acrylic oligomers known as epoxy acrylate, urethane acrylate, polyester acrylate, polyether acrylate, polybutadiene acrylate, silicone acrylate, and the like, and 2-ethylhexyl acrylate, isoamyl acrylate, butoxyethyl acrylate, ethoxydiglycol acrylate, phenoxyethyl acrylate, tetrahydroconyl acrylate, isobornyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-acryloxyphthalic acid, dicyclopentenyl acrylate, triethylene glycol diacrylate, neopentyl glycol diacrylate, 1, 6-hexanediol diacrylate, bisphenol A EO adduct diacrylate, and the like, Acrylate monomers such as trimethylolpropane triacrylate, EO-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, and the like. These compounds may be used alone or in combination of two or more. Although methacrylate esters can be similarly used, acrylate esters are generally preferred because they have a higher photopolymerization rate than methacrylate esters.

As the cation polymerizable compound, a compound having 1 or more epoxy groups, vinyl ether groups, and oxetane groups in the molecule can be used. Examples of the compound having an epoxy group include diglycidyl ethers of bisphenols such as 2-ethylhexyl glycol glycidyl ether, biphenyl glycidyl ether, bisphenol A, hydrogenated bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetrachlorobisphenol A and tetrabromobisphenol A, phenol novolacs, cresol novolacs and brominated phenol novolacs, glycidyl esters such as polyglycidyl ethers of novolak resins such as o-cresol novolak, diglycidyl ethers of alkylene glycols such as ethylene glycol, polyethylene glycol, polypropylene glycol, butanediol, 1, 6-hexanediol, neopentyl glycol, trimethylolpropane, 1, 4-cyclohexanedimethanol, EO adducts of bisphenol A, PO adducts of bisphenol A, and the like, glycidyl esters such as glycidyl esters of hexahydrophthalic acid, and diglycidyl esters of dimer acids.

As the compound having an epoxy group, there may be further exemplified, but not limited to: 3, 4-epoxycyclohexylmethyl-3 ', 4' -epoxycyclohexanecarboxylate, 2- (3, 4-epoxycyclohexyl-5, 5-spiro-3, 4-epoxy) cyclohexane-m-bisAlkanes, bis (3, 4-epoxycyclohexylmethyl) adipate, bis (3, 4-epoxy-6-methylcyclohexylmethyl) adipate, 3, 4-epoxy-6-methylcyclohexyl-3 ', 4' -epoxy-6 '-methylcyclohexanecarboxylate, methylenebis (3, 4-epoxycyclohexane), dicyclopentadiene diepoxide, bis (3, 4-epoxycyclohexylmethyl) ether of ethylene glycol, ethylenebis (3, 4-epoxycyclohexanecarboxylate), lactone-modified 3, 4-epoxycyclohexylmethyl-3', alicyclic epoxy compounds such as 4' -epoxycyclohexanecarboxylate, tetrakis (3, 4-epoxycyclohexylmethyl) butanetetracarboxylate and bis (3, 4-epoxycyclohexylmethyl) -4, 5-epoxytetrahydrophthalate.

Examples of the compound having a vinyl ether group include, but are not limited to: 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, trimethylolpropane trivinyl ether, propenyl ether propylene carbonate, and the like. The vinyl ether compound is generally cationically polymerizable, but may be radically polymerized by combination with an acrylate.

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

The cationic polymerizable compounds described above may be used alone or in combination of two or more. The photopolymerizable compound is not limited to the above. In order to generate a sufficient refractive index difference, fluorine atoms (F) may be introduced into the photopolymerizable compound to achieve a low refractive index, or sulfur atoms (S), bromine atoms (Br), or various metal atoms may be introduced to achieve a high refractive index. Further, as disclosed in Japanese patent application laid-open No. 2005-514487, titanium oxide (TiO) is added to the photopolymerizable compound₂) Zirconium oxide (ZrO)₂) Tin oxide (SnO)_x) Functional ultrafine particles comprising ultrafine particles of a metal oxide having a high refractive index, in which a photopolymerizable functional group such as an acrylic group, a methacrylic group, or an epoxy group is introduced into the surface of the ultrafine particles, are also effective.

As the photopolymerizable compound according to the present invention, a photopolymerizable compound having a silicone skeleton is preferably used. The photopolymerizable compound having an organosilicon skeleton is polymerized and cured with its structure (mainly ether bond) oriented to form a low refractive index region, a high refractive index region, or a low refractive index region and a high refractive index region. By using a photopolymerizable compound having a silicone skeleton, the columnar region can be easily inclined, and the light-condensing property in the front direction can be improved. The low refractive index region corresponds to either the columnar region or the matrix region, and the other corresponds to the high refractive index region.

In the low refractive index region, it is preferable that the silicone resin as a cured product of the photopolymerizable compound having a silicone skeleton is relatively large. This makes it possible to further facilitate the inclination of the scattering center axis, thereby improving the light converging property in the front direction. Since the silicone resin contains more silicon (Si) than a compound having no silicone skeleton, the relative amount of the silicone resin can be confirmed by using EDS (energy dispersive X-ray spectrometer) with the silicon as an index.

The photopolymerizable compound having a silicone skeleton is a monomer, oligomer, prepolymer, or macromer having a radical polymerizable or cation polymerizable functional group. Examples of the radical polymerizable functional group include acryloyl, methacryloyl, and allyl; examples of the cationically polymerizable functional group include an epoxy group and an oxetanyl group. The kind and number of these functional groups are not particularly limited, and it is preferable that the crosslinking density is higher as the number of functional groups is larger, and the difference in refractive index is more likely to occur, and thus it is preferable that a polyfunctional acryloyl group or methacryloyl group is contained. Further, a compound having an organosilicon skeleton may have insufficient compatibility with other compounds due to its structure, and in such a case, urethanization may be performed to improve the compatibility. In this embodiment, a silicone-urethane- (meth) acrylate having an acryloyl group or a methacryloyl group at the end is preferably used.

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

The silicone skeleton corresponds to, for example, a structure represented by the following general formula (1). In the general formula (1), R₁、R₂、R₃、R₄、R₅、R₆Each independently has a functional group such as a methyl group, an alkyl group, a fluoroalkyl group, a phenyl group, an epoxy group, an amino group, a carboxyl group, a polyether group, an acryloyl group, or a methacryloyl group. In the general formula (1), n is preferably an integer of 1 to 500.

[ solution 1]

When a photopolymerizable compound having a silicone skeleton is blended with a compound having no silicone skeleton to form an anisotropic light diffusion layer, a low refractive index region and a high refractive index region separated from each other are easily formed, and the degree of anisotropy is strong, which is preferable. The compound having no silicone skeleton may be a thermoplastic resin or a thermosetting resin other than the photopolymerizable compound, or may be used in combination. As the photopolymerizable compound, a polymer, an oligomer, or a monomer having a radical polymerizable or cation polymerizable functional group (but not having a silicone skeleton) can be used. Examples of the thermoplastic resin include polyesters, polyethers, polyurethanes, polyamides, polystyrenes, polycarbonates, polyacetals, polyvinyl acetates, acrylic resins, copolymers thereof, and modified products thereof. In the case of using a thermoplastic resin, the resin is dissolved in a solvent in which the thermoplastic resin is dissolved, coated and dried, and then the photopolymerizable compound having a silicone skeleton is cured by ultraviolet rays to mold the anisotropic light diffusion layer. Examples of the thermosetting resin include epoxy resins, phenol resins, melamine resins, urea resins, unsaturated polyesters, copolymers thereof, and modified products thereof. In the case of using a thermosetting resin, the photopolymerizable compound having a silicone skeleton is cured with ultraviolet rays and then appropriately heated to cure the thermosetting resin and mold the anisotropic light diffusion layer. The compound having no silicone skeleton is most preferably a photopolymerizable compound, and the low refractive index region and the high refractive index region are easily separated from each other, and therefore, a solvent in the case of using a thermoplastic resin is not required, a drying process is not required, a thermosetting process such as that of a thermosetting resin is not required, and the productivity is excellent.

The ratio of the photopolymerizable compound having an organosilicon skeleton to the compound having no organosilicon skeleton is preferably in the range of 15:85 to 85:15 in terms of mass ratio. More preferably in the range of 30:70 to 70: 30. Within this range, the low refractive index region and the high refractive index region are easily separated from each other, and the columnar region is easily inclined. If the ratio of the photopolymerizable compound having a silicone skeleton is less than the lower limit value or exceeds the upper limit value, phase separation becomes difficult and the columnar region becomes difficult to be inclined. When a silicone-urethane- (meth) acrylate is used as the photopolymerizable compound having a silicone skeleton, the compatibility with a compound having no silicone skeleton is improved. This makes it possible to incline the columnar region even if the mixing ratio of the materials is increased.

2-2-1-2. photoinitiator

Examples of the photoinitiator capable of polymerizing the radical polymerizable compound include benzophenone, benzil, michael ketone, 2-chlorothioxanthone, 2, 4-diethylthioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-diethoxyacetophenone, benzyl dimethyl ketal (ベンジルジメチルケタール), 2-dimethoxy-1, 2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropanone-1, 1- [4- (2-hydroxyethoxy) -phenyl ] -2-hydroxy-2-methyl- 1-propan-1-one, bis (cyclopentadienyl) -bis [2, 6-difluoro-3- (pyrrol-1-yl) phenyl ] titanium, 2-benzyl-2-dimethylamino-1- (4-morpholinylphenyl) -butanone-1, 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, and the like. These compounds may be used alone or in combination of two or more.

The photoinitiator of the cationically polymerizable compound is a compound which generates an acid by irradiation with light and polymerizes the cationically polymerizable compound using the generated acid, and it is generally preferable to useSalts, metallocene complexes. AsOnium salts, using diazonium, sulfonium, or iodineSalt,Salts, selenium salts, and the like, and anions such as BF 4-, PF 6-, AsF 6-, SbF 6-, and the like are used as the counter ion. Specific examples include, but are not limited to: 4-chlorophenyldiazo hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, (4-phenylthiophenyl) diphenylsulfonium hexafluoroantimonate, (4-phenylthiophenyl) diphenylsulfonium hexafluorophosphateBis [4- (diphenylsulfonium) phenyl]Thioether-bis-hexafluoroantimonate, bis [4- (diphenylsulfonium) phenyl]Thioether-bis-hexafluorophosphate, (4-methoxyphenyl) diphenylsulfonium hexafluoroantimonate, (4-methoxyphenyl) phenyliodideHexafluoroantimonate, bis (4-tert-butylphenyl) iodideHexafluorophosphate, benzyltriphenylHexafluoroantimonate, triphenylselenophosphoric acid ester, (. eta.5-isopropylbenzene) (. eta.5-cyclopentadienyl) iron (II) hexafluorophosphate, etc. These compounds may be used alone or in combination of two or more.

The photoinitiator according to the present invention is blended in an amount of 0.01 to 10 parts by mass, preferably 0.1 to 7 parts by mass, and more preferably about 0.1 to 5 parts by mass, based on 100 parts by mass of the photopolymerizable compound. This is because, if less than 0.01 parts by mass, the photocurability is lowered; when the amount is more than 10 parts by mass, the surface curing alone may deteriorate the internal curability, and coloring and formation of columnar regions may be inhibited. These photoinitiators are generally used by directly dissolving powder in a photopolymerizable compound, but when the solubility is poor, a photoinitiator dissolved in a very small amount of solvent at a high concentration in advance may be used. Such a solvent is photopolymerizable, and more preferably, propylene carbonate, γ -butyrolactone, and the like are specifically mentioned. In addition, various known dyes and sensitizers may be added to improve photopolymerization. Further, a thermal curing initiator which can cure the photopolymerizable compound by heating may be used together with the photoinitiator. In this case, by heating after photocuring, it is expected that polymerization curing of the photopolymerizable compound is further promoted and complete curing is achieved.

2-2-1-3. other optional ingredients

The anisotropic light diffusion layer can be formed by curing the photopolymerizable compound alone or by curing a composition obtained by mixing a plurality of photopolymerizable compounds. The anisotropic light diffusion layer according to the present invention may be formed by curing a mixture of a photopolymerizable compound and a polymer resin that is not photocurable. Examples of the polymer resin that can be used here include acrylic resins, styrene-acrylic copolymers, polyurethane resins, polyester resins, epoxy resins, cellulose resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, and polyvinyl butyral resins. These polymer resins and photopolymerizable compounds need to have sufficient compatibility before photocuring, and various organic solvents, plasticizers, and the like may be used to ensure the compatibility. When an acrylic ester is used as the photopolymerizable compound, the polymer resin is preferably selected from acrylic resins in view of compatibility.

Examples of the solvent used for preparing the composition containing the photopolymerizable compound include ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, toluene, and xylene.

2-2-2. procedure for manufacturing Anisotropic light-diffusing layer

Next, a manufacturing process (process) of the anisotropic light diffusion layer of the present embodiment will be described. First, the coating material containing the photopolymerizable compound is applied onto an appropriate substrate such as a transparent PET film to form a sheet-like film, and an uncured resin composition layer is provided. The light rays such as ultraviolet rays and/or visible light rays may be irradiated onto the uncured resin composition layer to produce an anisotropic light diffusion layer.

The step of forming the anisotropic light diffusion layer according to the present embodiment mainly includes the following steps.

(1) Step 1-1: process for providing uncured resin composition layer on substrate

(2) Step 1-2: procedure for obtaining parallel light from light source

(3) Optional procedures 1-3: a step of making the parallel light incident on the directional diffusion element to obtain the light with directivity

(4) Step 1 to step 4: curing the uncured resin composition layer by irradiating light to the uncured resin composition layer

Step 1-1: process for providing uncured resin composition layer on substrate

A method of applying a photopolymerizable compound to a substrate to form a film in a sheet form to form an uncured resin composition layer is a method of applying a general application method or a printing method. Specifically, air knife coating, bar coating, knife coating, reverse coating, transfer roll coating, gravure roll coating, kiss coating, cast coating, spray coating, slot nozzle coating, calender coating, weir plate coating, dip coating, die coating, gravure printing such as gravure printing, stencil printing such as screen printing, and the like can be used. When the composition has a low viscosity, a weir plate having a predetermined height may be provided around the substrate, and the composition may be put into the region surrounded by the weir plate.

In the step 1-1, in order to prevent oxygen inhibition (acid blocking) of the uncured resin composition layer and efficiently form the columnar regions that are the features of the anisotropic light diffusion layer according to the present embodiment, a mask that is in close contact with the light irradiation side of the uncured resin composition layer and locally changes the irradiation intensity of light may be stacked. The mask is preferably made of a material having a structure in which a light-absorbing filler such as carbon is dispersed in a matrix, and a part of incident light is absorbed by carbon and light is sufficiently transmitted through the mask opening. As such a substrate, a transparent plastic film such as PET, TAC, PVAc, PVA, acrylic acid, polyethylene, or an inorganic substance such as glass or quartz can be used.

Further, the mask sheet may also include a patterned, ultraviolet-absorbing pigment for controlling the amount of ultraviolet transmission.

In the case where such a mask is not used, oxygen inhibition of the uncured resin composition layer can also be prevented by performing light irradiation under a nitrogen atmosphere. Further, merely laminating a common transparent film on the uncured resin composition layer is also effective in preventing oxygen inhibition and promoting formation of columnar regions. In light irradiation through such a mask or transparent film, a photopolymerization reaction occurs in the composition containing the photopolymerizable compound according to the light irradiation intensity, and therefore, a refractive index distribution is likely to occur, and it is effective for producing the anisotropic light diffusion layer according to the present embodiment.

Step 1-2: procedure for obtaining parallel light from light source

As the light source, a short-arc ultraviolet light generating light source is generally used, and specifically, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, a xenon lamp, or the like can be used. In this case, it is necessary to obtain a light ray parallel to the desired scattering center axis, and such a parallel light ray can be obtained by, for example, the following method: a point light source is disposed, an optical lens such as a Fresnel lens for irradiating parallel rays is disposed between the point light source and the uncured resin composition layer, and a reflector is disposed behind the light source to emit light in a predetermined direction.

Step 1 to 4: a step of curing the uncured resin composition layer by irradiating light to the uncured resin composition layer (in the case where the optional step 1 to 3 are not performed)

The light to be irradiated to the uncured resin composition layer to cure the uncured resin composition layer must include a wavelength capable of curing the photopolymerizable compound, and is generally light having a wavelength of 365nm centered on a wavelength of a mercury lamp. When an anisotropic light diffusion layer is produced using this wavelength band, the illuminance is preferably 0.01mW/cm²～100mW/cm²More preferably 0.1mW/cm²～20mW/cm². Because if the illuminance is less than 0.01mW/cm²A long time is required for curing, and thus production efficiency is deteriorated; if it exceeds 100mW/cm²The photopolymerizable compound is cured too quickly, and the structure is not formed, and the target optical characteristics cannot be expressed. The light irradiation time is not particularly limited, but is preferably 10 seconds to 180 seconds, and more preferably 30 seconds to 120 seconds. By irradiating the light beam, the anisotropic light diffusion layer of the present embodiment can be obtained.

As described above, the anisotropic light diffusion layer of the present embodiment is formed by irradiating a long period of low-illuminance light to form a specific internal structure in the uncured resin composition layerAnd then obtaining the product. Therefore, only by such light irradiation, unreacted monomer components may remain and stickiness may occur, which may cause problems in handling and durability. In that case, additional irradiation of 1000mW/cm may be performed²The residual monomer is polymerized by the above high illumination light. The light irradiation at this time may be performed from the side opposite to the side where the mask is laminated.

Optional procedures 1-3: a step of making the parallel light incident on the directional diffusion element to obtain the light with directivity

Next, a production method including optional steps 1 to 3 will be described. In the production method including the optional step 1 to 3, the steps 1 to 1 and 1 to 2 are as described above, and the optional step 1 to 3 will be described later.

Fig. 8 is a schematic view showing a method of manufacturing an anisotropic light diffusion layer to which the present invention relates by optional processes 1 to 3.

The directional diffusion elements 301 and 302 used in the optional steps 1 to 3 may be any elements that provide directivity to the parallel light rays D incident from the light source 300. Fig. 8 shows that the light E having directivity enters the uncured resin composition layer 303 in a form in which a large amount of light is diffused in the X direction and almost no light is diffused in the Y direction. In order to obtain light having directivity in this manner, for example, the following method may be employed: the directional diffusion elements 301 and 302 contain needle-like fillers with a high aspect ratio, and at the same time, the needle-like fillers are oriented so that the long axis direction extends in the Y direction. The directional diffusion members 301 and 302 may use various methods other than the method using the needle-shaped filler.

Here, the aspect ratio of the light E having directivity is 20 or less, preferably 5 or less. A columnar region having an aspect ratio substantially corresponding to the aspect ratio is formed.

In the optional step 1-3, the shape of the principal plane surface of the columnar region to be formed (aspect ratio, short axis SA, long axis LA, etc.) can be appropriately determined by adjusting the width of the light E having directivity. For example, the anisotropic light diffusion layer of the present embodiment can be obtained in both of fig. 8(a) and (b). Fig. 8(a) and (b) differ in that the width of the light E having directivity is large in (a) and small in (b). The size of the main plane surface shape of the columnar region differs depending on the width of the light E having directivity.

The width of the light E having directivity mainly depends on the kind of the directional diffusion elements 301 and 302 and the distance from the uncured resin composition layer 303. As the distance is shortened, the size of the columnar region becomes smaller; as the distance increases, the size of the columnar region becomes larger. Therefore, the size of the columnar area can be adjusted by adjusting the distance.

Step 1 to 4: a step of curing the uncured resin composition layer by irradiating light to the uncured resin composition layer (in the case of performing the optional step 1-3)

The light for curing the uncured resin composition layer by irradiating the uncured resin composition layer through the directional diffusion member must include a wavelength capable of curing the photopolymerizable compound, and is generally light having a wavelength of 365nm centered by a mercury lamp. When an anisotropic light diffusion layer is produced using this wavelength band, the illuminance is preferably 0.01mW/cm²～100mW/cm²More preferably 0.1mW/cm²～20mW/cm². Because if the illuminance is less than 0.01mW/cm²A long time is required for curing, and thus production efficiency is deteriorated; if it exceeds 100mW/cm²The photopolymerizable compound is cured too quickly, and the structure is not formed, and the target optical characteristics cannot be expressed. The light irradiation time is not particularly limited, but is preferably 10 seconds to 180 seconds, and more preferably 30 seconds to 120 seconds. By irradiating the light beam, the anisotropic light diffusion layer of the present embodiment can be obtained.

The anisotropic light diffusion layer of the present embodiment can also be obtained by forming a specific internal structure in the uncured resin composition layer by irradiating light of low illuminance for a long time when the optional steps 1 to 3 are performed, as described above. Therefore, only by such light irradiation, unreacted monomer components may remain and stickiness may occur, which may cause problems in handling and durability. In that case, additional irradiation of 1000mW/cm may be performed²The residual monomer is polymerized by the above high illumination light. The light irradiation at this time may be performed from the side opposite to the side where the mask is laminated.

3. Use of a reflective display device according to the invention

The reflective display device of the present invention can be used as a display device used outdoors such as a tablet personal computer and a wearable device.

Examples

The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples at all.

< production of anisotropic optical films 1 to 6 for example >

A partition wall having a height of 50 μm was formed from a curable resin on the entire periphery of a 100 μm thick PET film (trade name: A4300, manufactured by Toyo Co.) using a dispenser. The following ultraviolet-curable resin coating was dropped thereon, and the surface of the dropped liquid film was covered with another PET film to prepare a liquid film of an uncured resin composition layer having a thickness of 50 μm.

(ultraviolet curable resin coating)

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 Co., Ltd.)

Neopentyl glycol diacrylate (refractive index: 1.450): 30 parts by weight (product name: Ebecryl145, Dailuoyanote Co., Ltd.)

EO adduct diacrylate of bisphenol A (refractive index: 1.536): 15 parts by weight (product name: Ebecyl150, Daluosite Co., Ltd.)

Phenoxyethyl acrylate (refractive index: 1.518): 40 parts by weight (product name: Lightacrylate PO-A, Co., Ltd.)

2, 2-dimethoxy-1, 2-diphenylethan-1-one: 4 parts by weight (product name: Irgacure651, manufactured by BASF Co., Ltd.)

The liquid film of the 50 μm thick uncured resin composition layer sandwiched between the PET films on both sides was irradiated with an irradiation intensity of 5mW/cm for 1 minute from an irradiation unit for epi-irradiation of a UV point light source (trade name: L2859-01, manufactured by Hamamatsu photoelectricity Co., Ltd.) directly or through a directional diffuser²Ultraviolet rays as parallel raysThe resultant was cured to obtain anisotropic light diffusion layers for 6 PET-equipped examples (anisotropic optical films 1 to 6 for examples) each having a PET film on both surfaces of a single-layer anisotropic light diffusion layer having a plurality of columnar regions as shown in fig. 4.

Specifically, the anisotropic optical films 1,4 to 6 were produced without using a directional diffusion element, and the anisotropic optical films 2 and 3 were produced using a directional diffusion element capable of changing the aspect ratio of parallel light rays.

In the production of the anisotropic optical film 6, parallel light rays are irradiated at an angle inclined by 25 ° with respect to the normal direction (surface normal direction) of the liquid film principal plane of the uncured resin composition layer.

The angle of the scattering center axis (normal direction to the anisotropic light diffusion layer) which is the optical characteristic of the anisotropic light diffusion layer is adjusted by adjusting the direction of the irradiated ultraviolet ray, the maximum linear transmittance is adjusted by adjusting the heating temperature of the ultraviolet curable resin composition for the liquid film, and the aspect ratio of the columnar region is adjusted by using a directional diffuser capable of changing the aspect ratio of the parallel rays.

The characteristics of the 6 types of anisotropic optical films for examples 1 to 6 thus produced are shown in table 1 below.

< production of anisotropic optical film 7 for example >

An anisotropic light diffusion layer for example with PET (anisotropic optical film for example 7) having a PET film on both surfaces of a single-layer anisotropic light diffusion layer having a plurality of columnar regions was obtained in the same manner as the anisotropic optical film 1 except that a partition wall having a height of 120 μm was formed and a liquid film of an uncured resin composition layer having a thickness of 120 μm was prepared. The properties are shown in Table 1.

< production of anisotropic optical film 1 for comparative example >

An anisotropic light diffusion layer for comparative example with PET (anisotropic optical film 1 for comparative example) having a PET film on both sides of a single-layer anisotropic light diffusion layer having a plurality of columnar regions was obtained in the same manner as the anisotropic optical film 1 except that a directional diffusion element capable of changing the aspect ratio of parallel light rays to 50 was used.

The properties of the anisotropic optical film 1 for comparative example thus produced are shown in table 1 below.

< determination of Anisotropic optical film >

The properties of the anisotropic optical films 1 to 7 for examples and the anisotropic optical film 1 for comparative examples in table 1 were measured in the following manner.

(measurement of haze value)

The haze value was measured in accordance with JIS K7136 using a haze meter NDH-2000 manufactured by Nippon Denshoku industries Co., Ltd.

(measurement of scattering center axis angle and maximum straight line transmittance of the Anisotropic light diffusion layer)

The linear transmittance of the anisotropic optical films (anisotropic light diffusion layers) for examples and comparative examples was measured using a variable angle photometer (manufactured by Genesia) capable of arbitrarily changing the light emission angle of the light source and the light reception angle of the detector as shown in fig. 7. The detector was fixed at a position to receive the straight light from the fixed light source, and the anisotropic optical films for examples and comparative examples were placed on the sample holder therebetween as a sample. As shown in fig. 7, the sample was rotated about a straight line V passing through the sample as a central axis of rotation, and the amount of straight-line transmitted light was measured for each incident light angle. By this evaluation method, it is possible to evaluate in what angle range the incident light is diffused. The straight line V is the same axis as the C-C axis in the structure of the sample shown in fig. 3. In the measurement of the amount of linearly transmitted light, the wavelength in the visible light region is measured using a luminosity filter. Based on the measurement results described above and the obtained optical profile, the maximum value of the linear transmittance (maximum linear transmittance) and the scattering center axis angle (i.e., the incident light angle when the optical profile is substantially symmetrical) at the incident light angle are obtained.

(measurement of aspect ratio of columnar regions (surface observation of anisotropic light diffusion layer))

One surface (light irradiation side at the time of ultraviolet irradiation) of each of the anisotropic optical films (anisotropic light diffusion layers) for examples and comparative examples was observed with an optical microscope, and the major and minor diameters of the plurality of columnar regions were measured. The average major axis and the average minor axis were calculated as an average of 20 arbitrary structures. Further, the average major axis and the average minor axis obtained were calculated as an aspect ratio.

[ Table 1]

Type number of anisotropic optical film	Haze value	Scattering center axis angle	Maximum linear transmittance	Aspect ratio
					Anisotropic optical film 1 for examples	71％	About 0 °	31％	1.1
Anisotropic optical film 2 for examples	72％	About 0 °	35％	5
					Anisotropic optical film 3 for examples	70％	About 0 °	42％	19
Anisotropic optical film 4 for examples	53％	About 0 °	55％	1.1
					Anisotropic optical film 5 for examples	86％	About 0 °	17％	1.1
Anisotropic optical film 6 for examples	70％	About 25 °	30％	1
					Anisotropic optical film 7 for examples	92％	About 0 °	12％	1.1
Anisotropic optical film 1 for comparative example	70％	About 0 °	65％	50

Production of reflective display device

The polarizing plates and the retardation plates on the visual recognition side surface of the liquid crystal panel of a commercially available TN-mode reflective liquid crystal display were peeled off, and the anisotropic optical films 1 to 7 for examples and the anisotropic optical film 1 for comparative examples prepared above were laminated and bonded to the exposed front glass surface via a transparent adhesive layer having a thickness of 10 μm, and then the retardation plate surfaces to which the peeled polarizing plates and the retardation plates were laminated to the exposed anisotropic optical film surfaces via a transparent adhesive layer having a thickness of 10 μm, to obtain reflective display devices of examples 1 to 7 and comparative example 1.

In addition, the reflective display device of comparative example 2 was directly used as a reflective display device without using an anisotropic optical film.

The characteristics of the reflective display devices of examples 1 to 7 and comparative examples 1 to 2 are shown in table 2 below.

Fig. 9 shows photographs of images of the reflective display devices of example 1 and comparative example 2 (the adjacent left side is example 1, and the right side is comparative example 2).

< test of functionality >

The functional tests of the reflective display devices of examples 1 to 7 and comparative examples 1 to 2 were carried out. The results of evaluation according to the following evaluation criteria are shown in table 2.

(evaluation Standard for paper whiteness feeling)

O: background color of white observed (white display)

And (delta): slight white was observed as background color (white display)

X: the background color (white display) was slightly observed to be yellow

(dazzling evaluation criteria)

O: without glare caused by interference

And (delta): although somewhat harsh, within the allowable range

X: the glare was clearly observed

(evaluation criteria for blur feeling)

O: clearly observing image display

And (delta): slight blurring of the image display was observed

X: image display blur is observed

[ Table 2]

	Type number of anisotropic optical film used	Feeling of whiteness	Dazzling	Feeling of blur
					Example 1	Anisotropic optical film 1 for examples	○	○	○
Example 2	Anisotropic optical film 2 for examples	○	○	○
					Example 3	Anisotropic optical film 3 for examples	○	△	○
Example 4	Anisotropic optical film 4 for examples	△	○	○
					Example 5	Anisotropic optical film 5 for examples	○	○	△
Example 6	Anisotropic optical film 6 for examples	○	○	○
					Example 7	Anisotropic optical film 7 for examples	○	○	△
Comparative example 1	Anisotropic optical film 1 for comparative example	○	×	○
					Comparative example 2	Is free of	×	○	○

From the results shown in table 2, the reflection-type display devices of examples 1 to 7 were Δ or more in all of the evaluations of the paper-white feeling, the dazzling feeling, and the blurring feeling. However, the reflective display device of example 7 was inferior in performance to the reflective display device of example 5 in evaluation of the feeling of blur.

Therefore, in the reflective display device using the anisotropic optical film of the present invention, the background color can be whitened, and a paper-white feeling can be imparted. In addition, no visual recognizability degradation due to glare or significant deterioration of the feeling of blur was observed.

In particular, the reflective display devices of examples 1,2, and 6 had good balance of high-level characteristics in all the evaluation items of the paper whiteness, glare, and blur.

On the other hand, any of the evaluation items of the reflective display devices of comparative examples 1 to 2 was x.

The glare x evaluation of the reflective display device of comparative example 1 is considered that the plurality of columnar regions of the anisotropic optical film 1 for comparative example have a louver structure with a large aspect ratio, and that stripes are formed in parallel in one direction in a plane parallel to the film surface, and light interference occurs.

Therefore, the reflective display device of comparative example 1 was more dazzling and had poor visibility than the reflective display device using the anisotropic optical film according to the example of the present invention.

The reflective display device of comparative example 2 did not use an anisotropic optical film, and therefore the evaluation of the paper whiteness was x evaluation.

In this case, by providing the anisotropic optical film having a specific aspect ratio of the present invention on the viewing side of the reflective plate of the reflective display device, it is possible to provide a reflective display device having less glare and less blurring and having a sufficient paper-white feeling.

Description of the symbols

1. 300, and (2) 300: a light source for emitting light from a light source,

2: a detector for detecting the presence of a particle,

100: an inner surface reflection type display device (reflection type liquid crystal display device),

101: an outer reflection type display device (reflection type liquid crystal display device),

110: a liquid crystal layer which is formed on the substrate,

120: the back glass is provided with a glass plate,

121: the front glass is provided with a front glass plate,

130: a reflective plate (a metal electrode),

140: a back-side polarizing plate for polarizing light,

141: a front-side polarizing plate having a polarizing plate,

150: an anisotropic optical film comprising a film of a compound having a refractive index,

160: a back-side phase difference film having a back-side retardation film,

161: a positive phase difference film, a negative phase difference film,

170. 171: an adhesive layer, a pressure-sensitive adhesive layer,

180: a reflection plate (back reflection plate),

200. 250: an anisotropic light-diffusing layer comprising a layer of a light-diffusing material,

201. 211: a region of the substrate,

202. 212, and (3): the columnar areas are arranged in the vertical direction,

301. 302: the directional diffusion element is arranged in a direction parallel to the axis of the diffuser,

303: a layer of uncured resin composition.