Optical laminate, image display device and glass composite

Abstract

To provide an optical laminate, an image display device, and a glass composite which are capable of sufficiently shielding light emitted in a direction oblique to a normal direction of a film without occurrence of moire even in a case of being used in combination with a high-definition image display device.SOLUTION: An optical laminate includes, in order, at least a first light absorption anisotropic layer, a refractive index anisotropic layer formed of one or more layers that contain a liquid crystal compound having a twisted structure, and a second light absorption anisotropic layer, in which the first light absorption anisotropic layer and the second light absorption anisotropic layer contain an anisotropic absorbing material and each have an absorption axis that is aligned at an angle of 60° to 90° with respect to a film surface.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an optical laminate having a refractive index anisotropic layer containing a liquid crystal compound with a twisted structure and an optically absorptive anisotropic layer in which the absorption axis is oriented at an angle of 60 to 90 degrees relative to the film surface, an image display device in which this optical laminate is combined with a display device such as a liquid crystal display or an organic EL display, and a glass composite in which this optical laminate is combined with glass. [Background technology]

[0002] Image display devices such as liquid crystal display devices and organic electroluminescence (EL) display devices are widely used as displays for smartphones, laptops, etc. In recent years, these devices have become thinner and lighter, making them easier to carry, and as a result, they are increasingly being used in transportation such as trains and airplanes, as well as in public places such as libraries and restaurants. Therefore, due to the need to protect personal information, confidential information, etc., there is a demand for technology that prevents others from peeking at the content displayed on the image display device. In recent years, image display devices have also been used as in-vehicle displays installed inside automobiles. As in-vehicle displays have become larger, light emitted from the displays is reflected on the windshield and side windows, which can interfere with driving, creating a problem. Therefore, there is a demand for technology to prevent this reflection.

[0003] To prevent people from looking into a liquid crystal display device and to control the viewing angle, a technique is known in which an anisotropic light-absorbing layer having an absorption axis in the thickness direction is used in combination. For example, Patent Documents 1 and 2 propose polarizing elements related to a viewing angle control system that use a film containing a dichroic material and in which the angle between the absorption axis and the normal to the film surface is 0° to 45°.

[0004] Patent Document 3 discloses a viewing angle control system in which light-transmitting regions and light-absorbing regions are alternately arranged within the plane of a film to limit light emission in directions oblique to the normal direction of the film. This type of viewing angle control system is generally called a louver film. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4902516 [Patent Document 2] International Publication No. 2018 / 079854 [Patent Document 3] Patent No. 6345732 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-165201 Summary of the Invention [Problem to be solved by the invention]

[0006] The louver film described in Patent Document 3 is capable of sufficiently blocking light that is emitted in a direction oblique to the normal direction of the film, and is therefore commonly used to prevent people from peeking at laptop computers and to prevent reflections of in-vehicle displays on the windshield and side windows. However, because louver films have alternating light-transmitting and light-absorbing regions stacked at a pitch of several tens of micrometers, their periodic structure can interfere with the pixels of image display devices, resulting in striped patterns known as moiré. In particular, as image display devices in recent years have become increasingly fine-grained, the problem of moiré is becoming more pronounced. Furthermore, louver films generally have a base layer made of a polycarbonate film or the like and are 300 μm or thicker, making them difficult to fold. In recent years, some image display devices used as in-vehicle displays and the like have curved display surfaces, making it difficult to apply louver films to these image display devices. Furthermore, because louver film controls the viewing angle in the vertical or horizontal direction, in order to control the viewing angle only in the front direction, with the aim of preventing people from looking at laptops and preventing reflections of in-car displays on the windshield or side windows, it is necessary to stack two pieces of louver film, one vertical and one horizontal. However, this poses issues such as reduced brightness from the front and reduced display quality due to moire and blurred images.

[0007] The viewing angle control systems described in Patent Documents 1 and 2 can be used without generating moire because they do not have a periodic structure that interferes with the pixels of an image display device. Furthermore, the viewing angle control systems described in Patent Documents 1 and 2 have polarizers with a thickness of several to several tens of micrometers, and the overall thickness can be made thin even including other base layers, so they can easily conform to curved surfaces. However, according to the inventors' investigations, the viewing angle control systems described in Patent Documents 1 and 2 are unable to sufficiently reduce the transmittance in directions oblique to the normal direction of the film, and therefore do not adequately block light that is emitted obliquely, and therefore do not have sufficient light-blocking performance to be used for preventing peeping at laptop computers and the like, and for preventing reflections on the windshield and side windows of in-vehicle displays. Furthermore, the viewing angle control system described in Patent Document 4 discloses a configuration in which a λ / 2 retardation is sandwiched between polarizers having polarization axes in the vertical direction. However, according to studies by the present inventors, even in the viewing angle control system described in Patent Document 4, it is not possible to sufficiently reduce the transmittance in a direction oblique to the normal direction of the film, and it has been found that the blocking of obliquely emitted light is insufficient.

[0008] The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an optical laminate, an image display device, and a glass composite that do not generate moire even when used in combination with a high-definition image display device, and that can sufficiently block light that is emitted in a direction oblique to the normal direction of the film. [Means for solving the problem]

[0009] As a result of extensive research, the inventors have found that excellent field of view control is possible by combining an optical laminate having a refractive index anisotropic layer containing a liquid crystal compound having a twisted structure with an optical absorption anisotropic layer whose absorption axis is oriented at an angle of 60 to 90 degrees relative to the film surface on the display surface or BL (backlight) side of a display device such as a liquid crystal display.

[0010] <1> The liquid crystal display device has at least a first optically absorptive anisotropic layer, one or more refractive index anisotropic layers containing a liquid crystal compound having a twisted structure, and a second optically absorptive anisotropic layer in this order, An optical laminate, wherein the first optically absorptive anisotropic layer and the second optically absorptive anisotropic layer contain an anisotropic absorbing material, and the absorption axis is oriented at an angle of 60 to 90 degrees with respect to the film surface. <2> The first optically absorptive anisotropic layer and the second optically absorptive anisotropic layer have their absorption axes oriented at an angle of 80 to 90 degrees relative to the film surface. <1> The optical laminate according to claim 1. <3> The twist angle of the refractive index anisotropic layer having the twist structure satisfies Formula I: <1> or <2> The optical laminate according to claim 1. 135·(2n-1) ≧ twist angle (degrees) ≧ 45·(2n-1) Formula I In the above formula I, n represents a natural number. <4> The birefringence anisotropic layer has a first substrate and a second substrate, at least one of which has a transparent electrode, disposed on both sides thereof, and the refractive index anisotropic layer is a liquid crystal cell, and the refractive index anisotropic layer, the first substrate, and the second substrate constitute a liquid crystal panel capable of electrically switching birefringence. <1> ~ <3> 10. The optical laminate according to claim 9, wherein the optical laminate is a laminate having a thickness of 100 nm or less <5> The liquid crystal cell is a TN liquid crystal cell capable of electrically switching birefringence or a VATN liquid crystal cell that exhibits a twisted structure when a voltage is applied. <4> The optical laminate according to claim 1. <6> The refractive index anisotropic layer is formed by polymerizing a composition containing a discotic liquid crystal compound or a rod-shaped liquid crystal compound fixed in a state of twist alignment in the film thickness direction. <1> ~ <3> 10. The optical laminate according to claim 9, wherein the optical laminate is a laminate having a thickness of 100 nm or less <7> The anisotropic absorbing material is a dichroic material. <1> ~ <6> 10. The optical laminate according to claim 9, wherein the optical laminate is a laminate having a thickness of 100 nm or less <8> The dichroic material is any one of a dichroic dye, a carbon nanotube, and an anisotropic metal nanoparticle. <7> The optical laminate according to claim 1. <9> The first optically absorptive anisotropic layer and the second optically absorptive anisotropic layer each contain a liquid crystal compound and at least one dichroic substance aligned perpendicular to the film surface. <7> or <8> The optical laminate according to claim 1. <10> The material of the anisotropic metal nanoparticles is at least one selected from gold, silver, copper, and aluminum. <8> The optical laminate according to claim 1. <11> A polarizer in which a liquid crystal compound and a dichroic material are aligned horizontally to the film surface is laminated on one or both of the first optically absorptive anisotropic layer and the second optically absorptive anisotropic layer. <1> ~ <10> 10. The optical laminate according to claim 9, wherein the optical laminate is a laminate having a thickness of 100 nm or less <12> <1> ~ <11> 10. An image display device having the optical laminate according to any one of the above items disposed on the front surface thereof. <13> <1> ~ <11> 10. An image display device in which the optical laminate according to any one of the preceding items is disposed between a liquid crystal cell and a backlight source. <14> <1> ~ <11> 10. An image display device comprising, in this order, the optical laminate according to any one of 1 to 9, a retardation layer, and a polarizer whose absorption axis is aligned horizontally to the film surface. <15> The display portion has a curved surface. <12> ~ <14> 10. The image display device according to claim 9, wherein: <16> At least with glass <1> ~ <11> and the optical laminate according to any one of the above. <17> It is a laminated glass having an intermediate layer between two glass sheets, and the intermediate layer is <1> ~ <11> A glass composite comprising the optical laminate according to any one of the preceding items. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an optical laminate, an image display device, and a glass composite that have high transmittance when viewed from the front direction and low transmittance in oblique directions. Furthermore, in a preferred embodiment of the present invention, by replacing a liquid crystal compound having a twist structure with a TN liquid crystal cell or a VATN liquid crystal cell, it is possible to provide an image display device that can electrically control a narrow field of view or a wide field of view by electrically controlling the refractive anisotropy of the liquid crystal layer. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram illustrating a prior art viewing angle control system. [Figure 2] 1 is a schematic diagram illustrating an example of an image display device having the optical laminate of the present invention. [Figure 3] FIG. 2 is a schematic view showing another example of an image display device having the optical laminate of the present invention. [Figure 4] FIG. 2 is a schematic view showing another example of an image display device having the optical laminate of the present invention. [Figure 5] FIG. 2 is a schematic view showing another example of an image display device having the optical laminate of the present invention. [Figure 6] FIG. 2 is a schematic view showing another example of an image display device having the optical laminate of the present invention. [Figure 7] FIG. 2 is a schematic view showing another example of an image display device having the optical laminate of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below. The following description of the components may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0014] In this specification, "parallel" and "orthogonal" do not mean "parallel" or "orthogonal" in the strict sense, but mean a range of ±5° from parallel or orthogonal. Furthermore, in this specification, unless otherwise specified, "polar angle" means the angle with respect to the normal direction of the film.

[0015] In this specification, the liquid crystal composition and liquid crystal compound conceptually include those that no longer exhibit liquid crystallinity due to curing or the like.

[0016] In addition, in this specification, each component may be a substance corresponding to the component, and may be used alone or in combination of two or more. Here, when two or more substances are used in combination for each component, the content of that component refers to the total content of the substances used in combination, unless otherwise specified. Furthermore, in this specification, "(meth)acrylate" is a notation representing "acrylate" or "methacrylate", "(meth)acrylic" is a notation representing "acrylic" or "methacrylic", and "(meth)acryloyl" is a notation representing "acryloyl" or "methacryloyl".

[0017] In the present invention, the refractive indices nx and ny are the refractive indices in the in-plane direction of the optical member. Typically, nx is the refractive index in the slow axis direction, and ny is the refractive index in the fast axis direction (i.e., the direction perpendicular to the slow axis). nz is the refractive index in the thickness direction. nx, ny, and nz can be measured, for example, using an Abbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.) with a sodium lamp (λ = 589 nm) as the light source. Wavelength dependence can also be measured using a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) in combination with an interference filter. Values ​​from the Polymer Handbook (John Wiley & Sons, Inc.) and catalogs for various optical films can also be used.

[0018] In this specification, Re(λ) and Rth(λ) represent the in-plane retardation and the thickness retardation at wavelength λ, respectively, and are expressed by the following formulas (1) and (2) using refractive indices nx, ny, and nz and film thickness d (μm). Equation (1): Re(λ)=(nx-ny)×d×1000(nm) Equation (2): Rth(λ)=((nx+ny) / 2-nz)×d×1000(nm) Unless otherwise specified, the wavelength λ is 550 nm. The slow axis direction, Re(λ), and Rth(λ) can be measured using, for example, AxoScan OPMF-1 (manufactured by Optoscience).

[0019] In this specification, Δnd indicates the retardation of a twisted rod-shaped or discotic liquid crystal compound and a TN or VATN liquid crystal cell, and is expressed as the product of the liquid crystal layer thickness d and the birefringence Δn of the liquid crystal. The twist angle indicates the degree to which the liquid crystal director of the refractive index anisotropic layer rotates above and below the substrate. In addition, it is preferable that the refractive index anisotropic layer having a twisted structure in the present invention satisfies the following formula, since the effects of the present invention can be obtained. Equation (3): 200nm≦Δn·d≦1500nm. Equation (4): 135·(2n-1) ≧ twist angle (degrees) ≧ 45·(2n-1) In the above formula (4), n is a natural number. Unless otherwise specified, Δn is the value at a wavelength of 550 nm.

[0020] Description of the Prior Art. First, the mechanism for controlling the viewing angle in the conventional viewing angle control system described in Patent Document 1 will be described. Fig. 1 is a cross-sectional view of a conventional viewing angle control system in which an optically absorptive anisotropic layer 101a having an absorption axis 11 in the normal direction of the film and a second polarizer 101b having an absorption axis 21 in the in-plane direction of the film are laminated on a display device 200 such as a liquid crystal display, an organic EL display, or a μLED display. As shown in Fig. 1, when the viewing angle control system is viewed from the front 1 (i.e., the normal direction of the film), the absorption axis 11 is horizontal to the line of sight, and therefore the optically absorptive anisotropic layer 101a does not absorb light traveling in the line of sight. Therefore, the conventional viewing angle control system transmits light. On the other hand, when the conventional viewing angle control system is viewed from an oblique azimuth 2, the orientations of the absorption axis 21 of the optically absorptive anisotropic layer 101a, which has an absorption axis 11 in the normal direction of the film, and the absorption axis 21 of the second polarizer layer 101b, which has an absorption axis 21 in the in-plane direction of the film, are perpendicular to each other, so light does not transmit, and light does not leak sideways. Furthermore, when the conventional viewing angle control system is viewed from the top-bottom direction (the depth direction of the paper; not shown), the orientations of the absorption axis 21 of the optically absorptive anisotropic layer 101a, which has an absorption axis 11 in the normal direction of the film, and the absorption axis 21 of the second polarizer layer 101b, which has an absorption axis 21 in the in-plane direction of the film, are parallel to each other, so light transmits. Therefore, it was found that the conventional viewing angle control system does not provide sufficient light-blocking properties in all directions, and therefore does not provide sufficient light-blocking properties.

[0021] The present invention can realize an optical laminate that has high transmittance when viewed from the front direction and can reduce transmittance in oblique directions, and an image display device that can block light in all oblique directions and control the viewing angle, thereby providing high security and preventing peeping. Furthermore, the present invention can realize a viewing angle-controllable image display device that can electrically control narrow and wide viewing angles by replacing a liquid crystal compound having a twist structure with a TN liquid crystal cell or a VATN liquid crystal cell and electrically controlling the refractive anisotropy of the liquid crystal layer.

[0022] (Basic configuration of the optical laminate and image display device of the present invention) Next, the mechanism by which the light-blocking angle range is expanded in the optical laminate and image display device of the present invention will be described. As a result of further investigation, the present inventors have found that by laminating a refractive index anisotropic layer 102 having a 90° twist structure (optically rotatory) between two optically absorptive anisotropic layers 101a having an absorption axis 11 in the normal direction of the film on a display device 200 such as a liquid crystal display, an organic electroluminescence (EL) display, or a μLED display, as shown in FIG. 2, it is possible to block oblique light in all directions and achieve excellent viewing angle control. Furthermore, it has been found that the effects of the present invention can be achieved not only with rod-shaped liquid crystal compounds fixed in a state twisted in the film thickness direction, but also with discotic liquid crystals. Furthermore, the present inventors have found that the structure is not limited to a 90° twist structure, and that any structure that exhibits optical rotatory power is sufficient. More preferably, a refractive index anisotropic layer with a twist angle satisfying the following formula I can block oblique light and control the viewing angle. 135·(2n-1) ≧ twist angle (degrees) ≧ 45·(2n-1) Formula I In the above formula I, n represents a natural number. Furthermore, as a result of extensive research, the inventors have realized an image display device with high security and viewing angle control that can electrically switch between a security mode in which the transmittance when viewed from the front and the transmittance in oblique directions are high and a wide viewing angle mode in which the transmittance when viewed from the front and the oblique directions are high, by using an electrically controllable TN type liquid crystal cell or a VATN type liquid crystal cell that exhibits a twisted structure when a voltage is applied as disclosed in JP-A-10-123576 as the refractive index anisotropic layer 102c, as shown in Figure 3.

[0023] When the optical laminate of the present invention is observed from an oblique direction (a polar angle direction) relative to the film surface, the absorption axes 11 of the two optically absorptive anisotropic layers 101a are parallel. The refractive index anisotropic layer 102 disposed between the two optically absorptive anisotropic layers 101a rotates the polarization direction of incident linearly polarized light by approximately 90°. Therefore, the polarization direction of linearly polarized light that passes through one of the optically absorptive anisotropic layers 101a is rotated by approximately 90° by the refractive index anisotropic layer 102. As a result, the polarization direction of the linearly polarized light rotated by the refractive index anisotropic layer 102 becomes approximately parallel to the absorption axis direction of the other optically absorptive anisotropic layer 101a and is absorbed by the other optically absorptive anisotropic layer 101a. This blocks light obliquely relative to the film surface. Here, the refractive index anisotropic layer 102 can rotate incident light regardless of the polarization direction of the linearly polarized light, and therefore can block oblique light in all directions. A λ / 2 plate is known as an optical element that rotates the polarization direction of linearly polarized light by 90°, but because a λ / 2 plate only acts on linearly polarized light in a specific direction, it can block oblique light in a specific direction but cannot block oblique light in all directions. In contrast, the present invention uses a refractive index anisotropic layer with a twist structure, which makes it possible to block oblique light in all directions.

[0024] (An example of an embodiment of the image display device of the present invention) As shown in Figure 4, in a liquid crystal display (IPS, VA, TN, etc.) consisting of a liquid crystal panel 300 composed of a liquid crystal cell 301 and crossed Nicol polarizers 302a and 302b arranged above and below the liquid crystal cell 301, and a surface light source 400, an optical laminate of the present invention is provided between the liquid crystal panel 300 and the surface light source 400, in which a refractive index anisotropic layer 102 having a 90° twist structure (optically rotatory) is laminated between two light-absorbing anisotropic layers 101a having an absorption axis 11 in the normal direction of the film, thereby realizing an image display device that blocks oblique light in all directions.

[0025] (Another example of an embodiment of the optical laminate and image display device of the present invention) As shown in Figure 5, by using a TN-type liquid crystal cell whose birefringence can be electrically controlled or a VATN-type liquid crystal cell that exhibits a twisted structure when a voltage is applied as disclosed in JP-A-10-123576 in the refractive index anisotropic layer in the configuration of Figure 4, a highly secure image display device capable of controlling the viewing angle can be realized, which can be electrically switched between a security mode in which the transmittance is high when viewed from the front direction and the transmittance in oblique directions is low, and a wide viewing angle mode in which the transmittance is high both from the front direction and in oblique directions. In other words, a liquid crystal panel may be constructed by providing a first substrate and a second substrate on each side of the refractive index anisotropic layer, and at least one of the first substrate and the second substrate having a transparent electrode.

[0026] (Another embodiment of the image display device of the present invention) As shown in Figure 6, an image display device capable of controlling the viewing angle to block oblique light in all directions has been realized by providing the optical laminate of the present invention on the viewing side of the liquid crystal panel 300 of a liquid crystal display (IPS, VA, TN, etc.) consisting of a liquid crystal cell 301 and crossed Nicol polarizers 302a and 302b arranged above and below the liquid crystal cell 301, and a surface light source 400, in which a refractive index anisotropic layer 102 having a 90° twist structure (optically rotatory) is laminated between two light-absorbing anisotropic layers 101a having an absorption axis 11 in the normal direction of the film.

[0027] (Another embodiment of the optical laminate of the present invention) The optical laminate of the present invention may have a configuration in which a light-absorbing anisotropic layer (polarizer layer) in which a liquid crystal compound and a dichroic material are oriented horizontally to the film surface is laminated on one or both of the first light-absorbing anisotropic layer and the second light-absorbing anisotropic layer. With this configuration, the polarizer layer can be used as a polarizer in a liquid crystal panel. The polarizer layer can also be used as an anti-reflection polarizer in an organic electroluminescence (EL) display device, a micro LED display device, or the like. In this way, an image display device capable of controlling the viewing angle to block oblique light in all directions can be configured. When the optical laminate is used in combination with an image display device, if the image display device has a polarizer (polarizing plate), such as a liquid crystal display, the polarizer of the image display device may be used as the polarizer layer.

[0028] (Another embodiment of the optical laminate and image display device of the present invention) 7 includes a liquid crystal display (IPS, VA, TN, etc.) including a liquid crystal panel 300 composed of a liquid crystal cell 301 and crossed Nicol polarizers 302a and 302b arranged above and below the liquid crystal cell 301, and a surface light source 400, an optical laminate of the present invention on the viewing side of the liquid crystal panel 300, in which a refractive index anisotropic layer 102c having a 90° twist structure (optically rotatory) is laminated between two light absorption anisotropic layers 101a having an absorption axis 11 in the normal direction of the film, and a retardation layer 500 arranged between the optical laminate and the liquid crystal panel 300. That is, the example shown in FIG. 7 includes an optical laminate, a retardation layer, and a polarizer in this order.

[0029] When an optical laminate and a polarizer are combined, a light-blocking state always occurs in a certain azimuth direction. Therefore, when a refractive index anisotropic layer 102c is used as the refractive index anisotropic layer, which is electrically switchable between a mode in which the transmittance in oblique directions is low using an electrically birefringence-controllable liquid crystal layer and a wide viewing angle mode in which the transmittance in the front direction and oblique directions is high, a light-blocking state occurs in a certain azimuth direction even in the wide viewing angle mode. In response to this, by providing a retardation layer between the optical laminate and the polarizer, it is possible to prevent the light from being constantly blocked in a certain azimuth direction, and to increase the transmittance in oblique directions in all directions in the wide viewing angle mode.

[0030] As the retardation layer, a general λ / 4 retardation plate or an O-plate whose slow axis is tilted with respect to the film surface can be suitably used.

[0031] The optical laminate of the present invention and the optical member that can be used in the image display device will be described in detail below.

[0032] (light absorption anisotropic layer) The first optically absorptive anisotropic layer and the second optically absorptive anisotropic layer (hereinafter collectively referred to as optically absorptive anisotropic layers) of the present invention are characterized in that the direction of their absorption axes forms an angle of 60° to 90° with respect to the film surface. The direction of the absorption axes of the optically absorptive anisotropic layers substantially coincides with the direction in which the transmittance of the image display device is maximized. For example, when used to prevent peeping of an image display device, it is preferable to maximize the transmittance in the front direction. In this case, the absorption axis of the optically absorptive anisotropic layer may be aligned with the normal direction of the film and perpendicular to the film surface. From the viewpoint of maximizing the transmittance in the front direction, it is preferable that the absorption axis of the optically absorptive anisotropic layer is oriented at an angle of 80 to 90 degrees with respect to the film surface. The absorption axis of the optically absorptive anisotropic layer may be oriented in different directions depending on the location. For example, in an in-vehicle display having a curved display surface, it is preferable to adjust the direction of the absorption axis of the optically absorptive anisotropic layer to match the curved surface so that emitted light from any position is not reflected on the windshield or the like and can be properly viewed by the driver.

[0033] The optically absorptive anisotropic layer of the present invention may have at least one dichroic material (dye) oriented perpendicular to the film surface. The optically absorptive anisotropic layer may also contain multiple dichroic materials. For example, it preferably contains a cyan dye that exhibits dichroism in the red wavelength range, a magenta dye that exhibits dichroism in the green wavelength range, and a yellow dye that exhibits dichroism in the blue wavelength range. The inclusion of multiple dichroic materials can neutralize the color and exert a viewing angle control effect over the entire wavelength range of visible light. It should be noted that a dichroic substance is a substance that exhibits dichroism, and dichroism means a property in which the absorbance varies depending on the direction of polarization. The degree of orientation of the dichroic material at a wavelength of 550 nm is preferably 0.95 or more. When the degree of orientation of the dichroic material is 0.95 or more, the transmittance in the direction of the absorption axis (i.e., the direction in which light is desired to be transmitted) can be increased. Furthermore, in terms of making the color neutral, the degree of orientation of the dichroic material at a wavelength of 420 nm is preferably 0.93 or more. The thickness of the optically absorptive anisotropic layer is not particularly limited, but from the viewpoint of flexibility, it is preferably 100 to 8000 nm, and more preferably 300 to 5000 nm.

[0034] [Dichroic substance] The dichroic substance used in the present invention is not particularly limited as long as it exhibits dichroism, and examples thereof include dichroic dyes, dichroic azo compounds, ultraviolet absorbing substances, infrared absorbing substances, nonlinear optical substances, carbon nanotubes, anisotropic metal nanoparticles, inorganic substances, etc. Dichroic azo dye compounds are particularly preferred.

[0035] The dichroic azo dye compound used in the present invention is not particularly limited, and any conventionally known dichroic azo dye can be used. The dichroic azo dye compound may or may not exhibit liquid crystallinity. When the dichroic azo dye compound exhibits liquid crystallinity, it may exhibit either nematic or smectic properties. The temperature range in which the liquid crystal phase is exhibited is preferably room temperature (approximately 20°C to 28°C) to 300°C, and more preferably 50°C to 200°C from the viewpoints of ease of handling and suitability for production.

[0036] In the present invention, from the viewpoint of improving pressure resistance, it is preferable that the dichroic azo dye compound has a crosslinkable group. Specific examples of the crosslinkable group include a (meth)acryloyl group, an epoxy group, an oxetanyl group, and a styryl group, and among these, a (meth)acryloyl group is preferred.

[0037] When the dichroic substance is anisotropic metal nanoparticles, the material of the anisotropic metal nanoparticles is preferably at least one selected from gold, silver, copper, and aluminum.

[0038] [Liquid crystal compound] The light absorption anisotropic layer may contain a liquid crystalline compound, which can align the dichroic material with a high degree of orientation while preventing precipitation of the dichroic material. As the liquid crystal compound, either a low-molecular-weight liquid crystal compound or a high-molecular-weight liquid crystal compound can be used, and it is also preferable to use both in combination. Here, "low-molecular-weight liquid crystal compound" refers to a liquid crystal compound that does not have a repeating unit in its chemical structure. Also, "high-molecular-weight liquid crystal compound" refers to a liquid crystal compound that has a repeating unit in its chemical structure.

[0039] The low-molecular-weight liquid crystal compound may be either a compound exhibiting nematic liquid crystallinity or a compound exhibiting smectic liquid crystallinity, but from the viewpoint of a high degree of orientation, a compound exhibiting smectic liquid crystallinity is preferred, such as the liquid crystal compounds described in JP-A-2013-228706.

[0040] Examples of polymeric liquid crystalline compounds include the thermotropic liquid crystalline polymers described in JP 2011-237513 A. Furthermore, from the viewpoint of excellent strength (particularly, the flex resistance of the film), polymeric liquid crystalline compounds preferably have repeating units having a crosslinkable group at the end. Examples of crosslinkable groups include the polymerizable groups described in paragraphs

[0040] to

[0050] of JP 2010-244038 A. Among these, from the viewpoint of improving reactivity and synthetic suitability, acryloyl groups, methacryloyl groups, epoxy groups, oxetanyl groups, and styryl groups are preferred, and acryloyl groups and methacryloyl groups are more preferred.

[0041] When the light absorption anisotropic layer contains a polymeric liquid crystalline compound, the polymeric liquid crystalline compound preferably forms a nematic liquid crystalline phase. The temperature range in which the nematic liquid crystalline phase is exhibited is preferably room temperature (23°C) to 450°C, and from the viewpoints of handling and manufacturing suitability, preferably 50°C to 400°C.

[0042] The content of the liquid crystal compound in the light absorption anisotropic layer is preferably 25 to 2000 parts by mass, more preferably 100 to 1300 parts by mass, and even more preferably 200 to 900 parts by mass, relative to 100 parts by mass of the dichroic substance. When the content of the liquid crystal compound is within the above range, the degree of orientation of the dichroic substance is further improved. The liquid crystal compound may be contained alone or in combination of two or more. When two or more liquid crystal compounds are contained, the content of the liquid crystal compounds refers to the total content of the liquid crystal compounds.

[0043] [Additives] The optically absorptive anisotropic layer may further contain additives such as a solvent, a vertical alignment agent, an interfacial improver, a leveling agent, a polymerizable component, a polymerization initiator (e.g., a radical polymerization initiator), a durability improver, etc. Known additives can be used as appropriate.

[0044] [Base material layer] The optically absorptive anisotropic layer may have a substrate layer. The substrate layer is not particularly limited, but a transparent film or sheet is preferred, and known transparent resin films, transparent resin plates, transparent resin sheets, glass, etc. can be used. Examples of transparent resin films that can be used include cellulose acylate films (e.g., cellulose triacetate films, cellulose diacetate films, cellulose acetate butyrate films, and cellulose acetate propionate films), polyethylene terephthalate films, polyethersulfone films, polyacrylic resin films, polyurethane resin films, polyester films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films, polyether ketone films, and (meth)acrylonitrile films. Among these, cellulose acylate films are preferred, and cellulose triacetate films are particularly preferred, because they have high transparency, little optical birefringence, are easy to produce, and are generally used as protective films for polarizing plates. The thickness of the transparent substrate film is preferably 20 μm to 100 μm.

[0045] [Alignment film] The optically absorptive anisotropic layer may have an alignment film between the substrate layer and the optically absorptive anisotropic layer. The alignment film may be any layer as long as it can cause the dichroic substance (liquid crystal compound) to be aligned in a desired state on the alignment film. For example, a film formed from a polyfunctional acrylate compound or polyvinyl alcohol may be used, with polyvinyl alcohol being particularly preferred. By irradiating a photo-alignment film made of an azo compound or cinnamoyl compound with UV light from an oblique direction, it is possible to tilt the absorption axis relative to the normal direction of the film.

[0046] [Barrier layer] The optically anisotropic layer preferably has a barrier layer. Here, the barrier layer is also called a gas barrier layer (oxygen barrier layer), and has the function of protecting the light absorption anisotropic layer from gases such as oxygen in the atmosphere, moisture, or compounds contained in adjacent layers. For the barrier layer, reference can be made to the descriptions in, for example, paragraphs

[0014] to

[0054] of JP 2014-159124 A, paragraphs

[0042] to

[0075] of JP 2017-121721 A, paragraphs

[0045] to

[0054] of JP 2017-115076 A, paragraphs

[0010] to

[0061] of JP 2012-213938 A, and paragraphs

[0021] to

[0031] of JP 2005-169994 A.

[0047] [Refractive index adjustment layer] The optically absorptive anisotropic layer may contain a dichroic material, and internal reflection due to the high refractive index of the optically absorptive anisotropic layer may become a problem. In such cases, it is preferable that a refractive index adjustment layer is present in the optical laminate. The refractive index adjustment layer is disposed in contact with the optically absorptive anisotropic layer and is a refractive index adjustment layer for so-called index matching, and preferably has an in-plane average refractive index of 1.55 to 1.70 at a wavelength of 550 nm.

[0048] [Method for forming optically absorptive anisotropic layer] The method for forming the optically absorptive anisotropic layer is not particularly limited, and examples thereof include a method including, in this order, a step of applying a composition for forming an optically absorptive anisotropic layer to form a coating film (hereinafter also referred to as a "coating film forming step") and a step of orienting a liquid crystalline component or a dichroic substance contained in the coating film (hereinafter also referred to as an "orientation step"). The liquid crystal component is a component including not only the above-mentioned liquid crystal compound but also a dichroic substance having liquid crystallinity when the above-mentioned dichroic substance has liquid crystallinity.

[0049] [Coating film formation process] The coating film forming step is a step of forming a coating film by applying a composition for forming an optically absorptive anisotropic layer. The use of a composition for forming an optically absorptive anisotropic layer that contains a solvent or that is made into a liquid such as a molten liquid by heating or the like makes it easier to apply the composition for forming an optically absorptive anisotropic layer. Specific examples of methods for applying the composition for forming an optically absorptive anisotropic layer include known methods such as roll coating, gravure printing, spin coating, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, die coating, spraying, and inkjet printing.

[0050] [Orientation process] The alignment step is a step of aligning the liquid crystal component contained in the coating film, thereby obtaining a light absorption anisotropic layer. The orientation step may include a drying treatment. By the drying treatment, components such as the solvent can be removed from the coating film. The drying treatment may be performed by leaving the coating film at room temperature for a predetermined time (for example, natural drying), or by heating and / or blowing air. Here, the liquid crystalline component contained in the composition for forming an optically absorptive anisotropic layer may be aligned by the above-mentioned coating film forming step or drying treatment. For example, in an embodiment in which the composition for forming an optically absorptive anisotropic layer is prepared as a coating liquid containing a solvent, the coating film is dried to remove the solvent from the coating film, thereby obtaining a coating film having optical absorption anisotropy (i.e., an optically absorptive anisotropic film). When the drying treatment is carried out at a temperature equal to or higher than the temperature at which the liquid crystalline component contained in the coating film transitions from the liquid crystal phase to the isotropic phase, the heating treatment described below does not need to be carried out.

[0051] The transition temperature from the liquid crystal phase to the isotropic phase of the liquid crystalline component contained in the coating film is preferably 10 to 250°C, more preferably 25 to 190°C, from the viewpoint of manufacturability, etc. A transition temperature of 10°C or higher is preferable because it eliminates the need for a cooling process or the like to lower the temperature to a temperature range in which the liquid crystal phase is exhibited. Furthermore, a transition temperature of 250°C or lower is preferable because it does not require a high temperature even when heating to the isotropic phase in order to suppress alignment defects, thereby reducing waste of thermal energy and deformation and deterioration of the substrate.

[0052] The alignment step preferably includes a heat treatment, which allows the liquid crystal component contained in the coating film to be aligned, and therefore the heat-treated coating film can be suitably used as an optically absorptive anisotropic film. From the viewpoint of manufacturability, the heat treatment temperature is preferably 10 to 250° C., more preferably 25 to 190° C. The heating time is preferably 1 to 300 seconds, more preferably 1 to 60 seconds.

[0053] The alignment step may include a cooling treatment carried out after the heating treatment. The cooling treatment is a treatment in which the coated film after heating is cooled to about room temperature (20 to 25°C). This allows the alignment of the liquid crystalline component contained in the coated film to be fixed. The cooling method is not particularly limited and can be carried out by a known method.

[0054] [Other processes] The method for forming the optically absorptive anisotropic layer may include a step of curing the optically absorptive anisotropic layer (hereinafter also referred to as a "curing step") after the above-mentioned alignment step. For example, when the optically absorptive anisotropic layer has a crosslinkable group (polymerizable group), the curing step is carried out by heating and / or light irradiation (exposure). Of these, the curing step is preferably carried out by light irradiation from the viewpoint of productivity. The light source used for curing can be various light sources such as infrared light, visible light, or ultraviolet light, but ultraviolet light is preferred. Furthermore, ultraviolet light may be irradiated while heating during curing, or ultraviolet light may be irradiated through a filter that transmits only specific wavelengths. When the exposure is carried out while heating, the heating temperature during exposure is preferably 25 to 140° C., although it depends on the transition temperature of the liquid crystal component contained in the liquid crystal film. The exposure may be carried out in a nitrogen atmosphere. When the curing of the liquid crystal film proceeds by radical polymerization, the exposure is preferably carried out in a nitrogen atmosphere, since this reduces the inhibition of polymerization by oxygen.

[0055] (Another type of optically absorptive anisotropic layer with an absorption axis in the vertical direction) The optically absorptive anisotropic layer may contain a dichroic dye and a guest-host liquid crystal material, as described in JP-A-2013-541727, and the orientation direction of the dichroic dye may be electrically controlled. This is preferable because it allows electrical switching between a state in which the viewing angle is controlled and a state in which the viewing angle is not restricted. This is also preferable because it allows electrical control of the absorption axis direction of the dichroic dye.

[0056] (refractive index anisotropic layer) The refractive index anisotropic layer in the present invention is disposed between two optically absorptive anisotropic layers. The refractive index anisotropic layer may be composed of one or more layers, but in the present invention, it is preferably composed of one or two layers. Furthermore, from the viewpoint of thinning the optical laminate or image display device, the thickness of the refractive index anisotropic layer is preferably thin as long as it does not impair optical properties, mechanical properties, and manufacturability. Specifically, the thickness is preferably 1 to 150 μm, more preferably 1 to 70 μm, and even more preferably 1 to 30 μm.

[0057] From the viewpoint of ease of production, the refractive index anisotropic layer having a twist structure is preferably a film having a twist structure formed by adding a chiral agent to a rod-shaped or discotic liquid crystal compound. Furthermore, in terms of achieving a thin structure, it can be made thinner than a retardation film using a polymer. On the other hand, when using a polymer film, obtaining a twist structure and optical rotation is difficult in terms of manufacturing, such as by laminating multiple polymer films with the slow axes of the polymer films at slightly different angles in-plane. However, the polymer film is preferably a cellulose acylate film, a cycloolefin polymer film (a polymer film using a cycloolefin polymer), a polycarbonate polymer film, a polystyrene polymer film, or an acrylic polymer film. The acrylic polymer film preferably contains an acrylic polymer containing at least one unit selected from a lactone ring unit, a maleic anhydride unit, and a glutaric anhydride unit.

[0058] [Refractive index anisotropic layer using liquid crystal compound] As the refractive index anisotropic layer formed using a liquid crystalline compound, a film in which the liquid crystalline compound is fixed in a twisted alignment state is preferred. Among them, a film obtained by forming a coating film by applying a composition containing a liquid crystalline compound having a polymerizable group, orienting the liquid crystalline compound in the coating film, and then performing a curing treatment to fix the alignment of the liquid crystalline compound is more preferred. The liquid crystal compound may be a rod-shaped liquid crystal compound or a discotic liquid crystal compound, and preferably has a polymerizable group to fix the alignment state. Furthermore, alignment at the desired twist angle can be achieved by adjusting the amount of chiral agent added. Furthermore, retardation layers using liquid crystal compounds are advantageous for thinning, and it is easy to reduce the thickness to 10 μm or less.

[0059] <Liquid crystal compounds> The liquid crystal compound includes rod-shaped liquid crystal compounds and discotic liquid crystal compounds. As the rod-shaped liquid crystal compound, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoates, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles are preferably used. Not only the above-mentioned low-molecular-weight liquid crystal molecules, but also polymeric liquid crystal molecules can be used.

[0060] It is more preferable to fix the orientation of the rod-shaped liquid crystal compound by polymerization. Examples of polymerizable rod-shaped liquid crystal compounds include those described in Makromol. Chem., Vol. 190, p. 2255 (1989); Advanced Materials 5, p. 107 (1993), U.S. Patent Nos. 4,683,327, 5,622,648, 5,770,107, WO95 / 22586, 95 / 24455, 97 / 00600, 98 / 23580, 98 / 52905, JP-A-1-272551, 6-16616, 7-110469, 11-80081, and Japanese Patent Application No. 2001-64627 can be used. Furthermore, as the rod-shaped liquid crystal compound, for example, those described in JP-T-11-513019 and JP-A-2007-279688 can also be preferably used.

[0061] As the discotic liquid crystal compound, for example, those described in JP-A No. 2007-108732 and JP-A No. 2010-244038 can be preferably used, but are not limited thereto. Preferred examples of the discotic liquid crystal compound are shown below, but the present invention is not limited to these.

[0062] [ka]

[0063] <Chiral Agents> A chiral agent is a compound used to adjust the helical period of a cholesteric liquid crystal compound, and is also called a chiral agent. In the present invention, various known chiral agents (e.g., those described in "Liquid Crystal Device Handbook," Chapter 3, Section 4-3, Chiral Agents for TN and STN, p. 199, edited by the First 42nd Committee of the Japan Society for the Promotion of Science, 1989) can be used. Chiral agents generally contain an asymmetric carbon atom, but axially asymmetric compounds or planarly asymmetric compounds without an asymmetric carbon atom can also be used as chiral agents. Examples of axially asymmetric compounds or planarly asymmetric compounds include binaphthyl, helicene, paracyclophane, and their derivatives. The chiral agent may have a polymerizable group. When the chiral agent has a polymerizable group and the rod-shaped liquid crystal compound used in combination also has a polymerizable group, a polymer having repeating units derived from the rod-shaped liquid crystal compound and repeating units derived from the chiral agent can be formed by polymerization of the chiral agent having a polymerizable group with the polymerizable rod-shaped liquid crystal compound. In this embodiment, the polymerizable group of the chiral agent having a polymerizable group is preferably the same type of group as the polymerizable group of the polymerizable rod-like liquid crystal compound. Therefore, the polymerizable group of the chiral agent is also preferably an unsaturated polymerizable group, an epoxy group, or an aziridinyl group, more preferably an unsaturated polymerizable group, and particularly preferably an ethylenically unsaturated polymerizable group.

[0064] The chiral agent may also be a liquid crystal compound. Examples of chiral agents exhibiting strong twisting power include those described in JP 2010-181852 A, JP 2003-287623 A, JP 2002-80851 A, JP 2002-80478 A, and JP 2002-302487 A, and these can be preferably used in the present invention. Furthermore, for the isosorbide compounds described in these publications, isomannide compounds having a corresponding structure can also be used, and for the isomannide compounds described in these publications, isosorbide compounds having a corresponding structure can also be used.

[0065] It is also preferable to use a liquid crystal compound that exhibits reverse dispersion wavelength dispersion as the liquid crystal compound. For example, the liquid crystal compound that exhibits reverse dispersion wavelength dispersion described in WO2017 / 043438 pamphlet can be mentioned. A refractive index anisotropic layer (retardation layer) using a liquid crystal compound that exhibits reverse dispersion wavelength dispersion can perform optical compensation over the entire wavelength range of visible light in a viewing angle control system. Here, the wavelength dispersion characteristic of reverse dispersion means that Re(λ) and Rth(λ) become larger as the wavelength λ increases.

[0066] When the refractive index anisotropic layer is a retardation film formed using a liquid crystal compound, it may have an alignment layer. Alignment layers are generally primarily composed of polymers. Polymer materials for alignment layers are described in numerous literature, and many commercially available products are available. The polymer materials used are preferably polyvinyl alcohol, polyimide, or derivatives thereof. Modified or unmodified polyvinyl alcohol is particularly preferred. For alignment layers that can be used in the present invention, see WO 01 / 88574 A1, page 43, line 24 to page 49, line 8, and Japanese Patent No. 3907735, paragraphs

[0071] to

[0095] . The alignment layer is usually subjected to a known rubbing treatment. Although a thinner alignment film is preferable, a certain thickness is required from the viewpoints of imparting alignment ability for forming a refractive index anisotropic layer and mitigating surface irregularities of the film to form a refractive index anisotropic layer with a uniform thickness. Specifically, the thickness of the alignment film is preferably 0.01 to 10 μm, more preferably 0.01 to 1 μm, and even more preferably 0.01 to 0.5 μm. In the present invention, it is also preferable to use a photo-alignment film. The photo-alignment film is not particularly limited, but the films described in paragraphs

[0024] to

[0043] of WO2005 / 096041 and the product name LPP-JP265CP manufactured by Rolic Technologies can be suitably used.

[0067] [Refractive index anisotropy layer using polymer film] When a retardation obtained by stretching a polymer film is used in the refractive index anisotropic layer, the retardation can be obtained by stretching a polymer film (e.g., cellulose acylate film, cyclic polyolefin film, polycarbonate film, polystyrene film, and copolymers containing methyl methacrylate, styrene, and maleic anhydride) produced by an appropriate method such as a melt-forming method or a solution-forming method, for example, by longitudinal stretching by controlling the peripheral speed of a roll, transverse stretching by a tenter, biaxial stretching, etc. More specifically, the description in JP-A-2005-338767 can be referred to. Alternatively, the film can be produced by laminating a shrinkable film to one or both sides of a polymer film, and then stretching it in the thickness (nz) direction by heating, as described in, for example, JP-A No. 5-157911, JP-A No. 2006-72309, or JP-A No. 2007-298960. The polymer film can be suitably used for producing, for example, a B plate. In order to produce a refractive index anisotropic layer having a negative Nz coefficient, it is preferable to use a polymer film exhibiting negative intrinsic birefringence, and for example, a film using a blend of a methyl methacrylate-methyl acrylate copolymer and a styrene-maleic anhydride copolymer, as described in Example 19 of JP-A-2008-262182, can be used.

[0068] It is also preferable to use a polymer film that exhibits reverse wavelength dispersion characteristics, such as modified polycarbonate film.

[0069] (Electrically controllable refractive index anisotropy layer) When the refractive index anisotropic layer is a liquid crystal cell, it is preferably a TN (Twisted Nematic) mode having a twist structure, but is not limited thereto. The inventors have found that the effects of the present invention can also be obtained with an STN (Super Twisted Nematic) mode having a twist angle of 180° or more. In a TN mode liquid crystal cell, rod-shaped liquid crystal molecules are aligned substantially horizontally when no voltage is applied, and further aligned with a twist angle of 60 to 120°. On the other hand, the inventors have also found that the excellent viewing angle control of the present invention is possible by using a liquid crystal of a VATN (Vertically Aligned Twisted Nematic) mode, in which rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied, and the liquid crystal layer is aligned with a twist angle of 60 to 120° when a voltage is applied, as disclosed in JP-A-10-123576.

[0070] (optical laminate) The optical laminate of the present invention is realized by combining two optically absorptive anisotropic layers and a refractive index anisotropic layer (FIG. 2). In general liquid crystal display devices, organic EL display devices, and the like, a polarizing plate having an absorption axis in the in-plane direction of the display surface is often laminated. Therefore, the optical laminate of the present invention can be attached to a polarizing plate already attached to a liquid crystal display device, organic EL display device, or the like to produce the image display device of the present invention, which is highly convenient.

[0071] (polarizer layer) The polarizer layer in the present invention can be a polarizer in which a general dichroic material, the absorption axis of which is parallel to the film surface, is horizontally oriented. For example, a polarizer in which a dichroic material is dyed into polyvinyl alcohol or other polymer resin and then stretched to be horizontally oriented may be used, or a polarizer in which a dichroic material is horizontally oriented by utilizing the orientation of a liquid crystal compound, as in the light absorption anisotropic layer of the present invention. Polarizers obtained by stretching polyvinyl alcohol and dyeing it with iodine are generally used as polarizer layers of polarizing plates installed in liquid crystal displays, organic EL displays, etc. Therefore, when the optical laminate of the present invention is used in liquid crystal displays, organic EL displays, etc., the polarizing plates installed in the liquid crystal displays, organic EL displays, etc. can also serve as polarizer layers.

[0072] The polarizer layer may be a reflective polarizer or a laminate of an absorptive polarizer (a normal polarizer) and a reflective polarizer. A reflective polarizer is a polarizer that reflects one polarized light and transmits the other polarized light. A reflective polarizer has a reflection axis and a transmission axis in the plane, but the reflection axis functions similarly to the absorption axis in a normal polarizer in the sense that it does not transmit polarized light in that direction. Therefore, in this specification, the reflection axis can be interpreted as the absorption axis. When the polarizer layer is a reflective polarizer, light that does not pass through the reflective polarizer is reflected. Therefore, for example, when the optical laminate is incorporated into the backlight side of a liquid crystal display device, the reflected light can be reused to improve the light utilization efficiency. As the reflective polarizer, brightness enhancement films "DBEF" or "APF" manufactured by 3M, wire grid polarizing film "WGF" manufactured by Asahi Kasei Corporation, and the like can be suitably used.

[0073] The optical laminate of the present invention includes at least a first optically absorptive anisotropic layer having a polarization axis in the vertical direction, a refractive index anisotropic layer, and a second optically absorptive anisotropic layer having a polarization axis in the vertical direction, and may also include other functional layers, such as an adhesive layer, a bonding layer, an antireflection layer, or a protective layer. The method for producing the optical laminate may include the steps of preparing the light absorption anisotropic layer, the refractive index anisotropic layer, and other functional layers, and bonding them together with a pressure-sensitive adhesive or adhesive. Furthermore, for example, the method may include a step of transferring a light absorption anisotropic layer formed on a substrate to a refractive index anisotropic layer. The method may also include a step of directly applying a refractive index anisotropic layer onto the optically absorptive anisotropic layer, or may include a step of forming a refractive index anisotropic layer and then directly forming a optically absorptive anisotropic layer on the refractive index anisotropic layer. Each step can be carried out according to a known method, and is not particularly limited.

[0074] (Image display device) The optical laminate of the present invention can be used in any image display device. The image display device is not particularly limited, and examples thereof include a liquid crystal display device, an organic EL display device, a micro LED display device, a head-up display, and a head-mounted display. As shown in Figure 4, a liquid crystal display device typically has a liquid crystal cell 301 and a backlight 400, with polarizing plates (302a, b) provided on both the viewing side and the backlight side of the liquid crystal cell 301. The optical laminate of the present invention can be applied to either the viewing side (Figure 6) or the backlight side (Figure 4) of the liquid crystal panel 300, or can be applied to both sides (not shown). In addition, the optical laminate of the present invention can be applied by laminating it to the polarizing plates on either or both sides of the liquid crystal panel 300. When the optical laminate of the present invention is applied to a liquid crystal display device, it is preferably disposed on the backlight side of the liquid crystal cell from the viewpoint of improving the display performance of the liquid crystal display device. Furthermore, when the optical laminate of the present invention is applied to the backlight side of the liquid crystal cell, it is preferable that the polarizer layer of the liquid crystal cell be a reflective polarizer or a laminate of a normal polarizer and a reflective polarizer from the viewpoint of improving the light utilization efficiency.

[0075] Some image display devices are thin and can be molded into a curved surface. The optical laminate of the present invention is thin and easily bendable, and therefore can be suitably applied to image display devices having a curved display surface. Furthermore, some image display devices have a pixel density of more than 250 ppi, making it possible to display images with high resolution. The optical laminate of the present invention can be suitably applied to such high-resolution image display devices without causing moire.

[0076] [Liquid crystal cell for display device] The liquid crystal cell used in the liquid crystal display device is preferably in VA (Vertical Alignment) mode, OCB (Optically Compensated Bend) mode, IPS (In-Plane-Switching) mode, or TN (Twisted Nematic) mode, but is not limited to these. In TN mode liquid crystal cells, rod-shaped liquid crystal molecules are aligned substantially horizontally when no voltage is applied, and are further aligned in a twisted orientation of 60 to 120 degrees. TN mode liquid crystal cells are most commonly used as color TFT (Thin Film Transistor) liquid crystal display devices, and are described in numerous literature. In VA-mode liquid crystal cells, rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied. VA-mode liquid crystal cells include (1) narrow-sense VA-mode liquid crystal cells in which rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied and substantially horizontally when voltage is applied (described in JP-A-2-176625), (2) multi-domain VA-mode liquid crystal cells (described in SID97, Digest of Tech. Papers (Proceedings) 28 (1997) 845) to widen the viewing angle, (3) n-ASM-mode liquid crystal cells in which rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied and are aligned in a twisted multi-domain manner when voltage is applied (described in Proceedings of the Japan Liquid Crystal Symposium 58-59 (1998)), and (4) SURVIVAL-mode liquid crystal cells (presented at LCD International 98). The liquid crystal display may be of any of a PVA (Patterned Vertical Alignment) type, an optical alignment type, and a PSA (Polymer-Sustained Alignment) type. Details of these modes are described in Japanese Patent Laid-Open No. 2006-215326 and Japanese Patent Laid-Open No. 2008-538819. In IPS mode liquid crystal cells, rod-shaped liquid crystal molecules are aligned substantially parallel to the substrates, and when an electric field parallel to the substrate surface is applied, the liquid crystal molecules respond in a planar manner. In IPS mode, black display occurs when no electric field is applied, and the absorption axes of a pair of upper and lower polarizing plates are perpendicular to each other. Methods for reducing light leakage during black display in oblique directions and improving the viewing angle using optical compensation sheets are disclosed in JP-A-10-54982, JP-A-11-202323, JP-A-9-292522, JP-A-11-133408, JP-A-11-305217, JP-A-10-307291, and the like.

[0077] [Organic EL display device] A preferred embodiment of an organic EL display device, which is one example of the image display device of the present invention, is one having, from the viewing side, the above-mentioned optical laminate of the present invention, a λ / 4 plate, and an organic EL display panel in this order. An organic EL display panel is a display panel configured using organic EL elements each having an organic light-emitting layer (organic electroluminescence layer) sandwiched between electrodes (a cathode and an anode). The configuration of the organic EL display panel is not particularly limited, and any known configuration may be used.

[0078] [Curved image display device] Examples of the curved image display device of the present invention are disclosed in JP-A-2017-181821, JP-A-2017-181819, JP-A-2017-102456, JP-A-2014-95901, and the like.

[0079] [Glass composite] The optical laminate of the present invention can be combined with glass. For example, by disposing the optical laminate of the present invention on a window glass surface, it is possible to prevent peeping. Furthermore, by disposing the optical laminate of the present invention on a glass surface on which sunlight is incident, it is possible to control sunlight, thereby reducing the power consumption of air conditioners in the summer. Furthermore, similar effects can be obtained when applied to vehicle windows.

[0080] The glass composite may be a laminated glass having an intermediate layer between two glass plates, and may have a configuration in which the intermediate layer contains the optical laminate of the present invention. [Example]

[0081] The present invention will be described in more detail below with reference to examples. The materials, reagents, amounts and proportions of substances, procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

[0082] [Fabrication of optically absorbing anisotropic layer] The optically absorptive anisotropic layer 101a used in the examples and comparative examples of the present invention was prepared as follows.

[0083] <Preparation of transparent support 1 with alignment film> The surface of a cellulose acylate film (40 μm thick TAC substrate; TG40 Fujifilm Corporation) was saponified with an alkaline solution, and the following coating solution 1 for forming an alignment layer was applied thereon using a wire bar. The cellulose acylate film on which the coating film was formed was dried with hot air at 60° C. for 60 seconds and then with hot air at 100° C. for 120 seconds to form an alignment layer PA1, and a transparent support 1 with an alignment layer was obtained. The thickness of the alignment film PA1 was 0.5 μm.

[0084] ---------------------------------------------------------------------------------- (Alignment layer forming coating liquid 1) ---------------------------------------------------------------------------------- 3.80 parts by mass of the following modified polyvinyl alcohol Initiator Irg2959 0.20 parts by mass ·Water 70 parts by mass Methanol 30 parts by weight ----------------------------------------------------------------------------------

[0085] Modified Polyvinyl Alcohol [ka]

[0086] <Formation of Optically Absorbent Anisotropic Layer P1 in Examples 1 to 9 and Comparative Example 1> On the obtained alignment layer PA1, the following composition 1 for forming an optically absorptive anisotropic layer was continuously applied with a wire bar to form a coating layer. The coated layer was then heated at 140° C. for 30 seconds and then cooled to room temperature (23° C.). It was then heated at 80°C for 60 seconds and cooled again to room temperature. Then, an LED lamp (center wavelength 365 nm) was used to illuminate the specimen at an intensity of 200 mW / cm 2 The light was irradiated for 2 seconds under the irradiation conditions, to form an optically absorptive anisotropic layer P1 on the alignment layer PA1. The optically absorptive anisotropic layer P1 had a film thickness of 3 μm and an orientation degree of 0.92 at 550 nm. The optically absorptive anisotropic layer P1 with a support thus obtained was designated as an optically absorptive anisotropic layer 101a. Furthermore, when the absorption axis of the optically absorptive anisotropic layer P1 was observed, it was found to be at an angle of 90 degrees to the film surface.

[0087] <Measurement of the orientation angle of the optically absorbing anisotropic layer> Using a polarimeter AxoScan OPMF-1 manufactured by Axometrics, the prepared optically absorptive anisotropic layer was placed horizontally on a sample stage, and P-polarized light was incident on the surface of the optically absorptive anisotropic layer while varying the azimuthal and polar angles of incidence, and the transmittance was measured to determine the azimuthal and polar angles at which the transmittance was maximized. Furthermore, a 2 μm-thick slice was cut using a microtome parallel to the azimuth angle at which the transmittance was maximized and parallel to the plane containing the normal to the surface of the optically absorbing anisotropic layer. The slice was placed on its side and placed on the rotating stage of a polarizing microscope to determine the azimuth angle of the slice (the angle at which the slice was rotated) at which the cross section of the optically absorbing anisotropic layer was most extinct with respect to incident linearly polarized light. In this way, the angle of the absorption axis of the optically absorbing anisotropic layer was measured.

[0088] ---------------------------------------------------------------------------------- (Light absorption anisotropic layer forming composition 1) ---------------------------------------------------------------------------------- 0.40 parts by weight of the following dichroic substance D-1 0.15 parts by weight of the following dichroic substance D-2 0.63 parts by weight of the following dichroic substance D-3 3.20 parts by mass of the following polymer liquid crystal compound P-1 0.45 parts by mass of the following low-molecular-weight liquid crystal compound M-1 Polymerization initiator IRGACUREOXE-02 (BASF) 0.040 parts by mass 0.060 parts by mass of the following compound E-1 0.060 parts by mass of the following compound E-2 0.010 parts by mass of the following surfactant F-1 0.015 parts by mass of the following surfactant F-2 Cyclopentanone 47.00 parts by mass Tetrahydrofuran 47.00 parts by mass Benzyl alcohol 1.00 parts by mass ----------------------------------------------------------------------------------

[0089] Dichroic substance D-1 [ka]

[0090] Dichroic substance D-2 [ka]

[0091] Dichroic substance D-3 [ka]

[0092] Polymer liquid crystal compound P-1 [ka]

[0093] Low molecular liquid crystal compound M-1 [ka]

[0094] Compound E-1 [ka]

[0095] Compound E-2 [ka]

[0096] Surfactant F-1 [ka]

[0097] Surfactant F-2 [ka]

[0098] <Preparation of Optically Absorbent Anisotropic Layer of Example 10> In Example 10, an optically absorptive anisotropic layer was formed in the same manner as for the optically absorptive anisotropic layer P1, except that the following composition 2 for forming an optically absorptive anisotropic layer was used.

[0099] ---------------------------------------------------------------------------------- (Light absorption anisotropic layer forming composition 2) ---------------------------------------------------------------------------------- 0.40 parts by mass of the above dichroic substance D-1 0.15 parts by weight of the above dichroic substance D-2 0.68 parts by mass of the above dichroic substance D-3 3.20 parts by mass of the polymer liquid crystal compound P-1 0.45 parts by mass of the low molecular weight liquid crystal compound M-1 Polymerization initiator IRGACUREOXE-02 (BASF) 0.040 parts by mass 0.060 parts by mass of the above compound E-1 0.060 parts by mass of the above compound E-2 0.010 parts by mass of the above surfactant F-1 0.015 parts by mass of the above surfactant F-2 Cyclopentanone 47.00 parts by mass Tetrahydrofuran 47.00 parts by mass Benzyl alcohol 1.00 parts by mass ----------------------------------------------------------------------------------

[0100] <Preparation of Optically Absorbent Anisotropic Layer of Example 11> In Example 11, an optically absorptive anisotropic layer was formed in the same manner as for the optically absorptive anisotropic layer P1, except that the following composition 3 for forming an optically absorptive anisotropic layer was used.

[0101] ---------------------------------------------------------------------------------- (Light absorption anisotropic layer forming composition 3) ---------------------------------------------------------------------------------- 0.40 parts by mass of the above dichroic substance D-1 0.09 parts by mass of the above dichroic substance D-2 0.69 parts by mass of the above dichroic substance D-3 3.20 parts by mass of the polymer liquid crystal compound P-1 0.45 parts by mass of the low molecular weight liquid crystal compound M-1 Polymerization initiator IRGACUREOXE-02 (BASF) 0.040 parts by mass 0.060 parts by mass of the above compound E-1 0.060 parts by mass of the above compound E-2 0.010 parts by mass of the above surfactant F-1 0.015 parts by mass of the above surfactant F-2 Cyclopentanone 47.00 parts by mass Tetrahydrofuran 47.00 parts by mass Benzyl alcohol 1.00 parts by mass ----------------------------------------------------------------------------------

[0102] <Preparation of Optically Absorbent Anisotropic Layer of Example 12> In Example 12, an optically absorptive anisotropic layer was formed in the same manner as for the optically absorptive anisotropic layer P1, except that the following composition 4 for forming an optically absorptive anisotropic layer was used.

[0103] ---------------------------------------------------------------------------------- (Light absorption anisotropic layer forming composition 4) ---------------------------------------------------------------------------------- Carbon nanotubes (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 0.56 parts by mass 3.20 parts by mass of the polymer liquid crystal compound P-1 0.45 parts by mass of the low molecular weight liquid crystal compound M-1 Polymerization initiator IRGACUREOXE-02 (BASF) 0.040 parts by mass 0.060 parts by mass of the following compound E-1 0.060 parts by mass of the following compound E-2 0.010 parts by mass of the following surfactant F-1 0.015 parts by mass of the following surfactant F-2 Cyclopentanone 47.00 parts by mass Tetrahydrofuran 47.00 parts by mass Benzyl alcohol 1.00 parts by mass ----------------------------------------------------------------------------------

[0104] <Preparation of Optically Absorbent Anisotropic Layer of Example 13> In Example 13, an optically absorptive anisotropic layer was formed in the same manner as for the optically absorptive anisotropic layer P1, except that the following composition for forming an optically absorptive anisotropic layer 5 was used.

[0105] ---------------------------------------------------------------------------------- (Light absorption anisotropic layer forming composition 5) ---------------------------------------------------------------------------------- Silver nanowires (manufactured by Aldrich) 0.66 parts by mass 3.20 parts by mass of the polymer liquid crystal compound P-1 0.45 parts by mass of the low molecular weight liquid crystal compound M-1 Polymerization initiator IRGACUREOXE-02 (BASF) 0.040 parts by mass 0.060 parts by mass of the above compound E-1 0.060 parts by mass of the above compound E-2 0.010 parts by mass of the above surfactant F-1 0.015 parts by mass of the above surfactant F-2 Cyclopentanone 47.00 parts by mass Tetrahydrofuran 47.00 parts by mass Benzyl alcohol 1.00 parts by mass ----------------------------------------------------------------------------------

[0106] [Fabrication of refractive index anisotropic layer] Various retardation layers used in the examples of the present invention were prepared as follows.

[0107] <Preparation of Retardation Layer (λ / 2) of Comparative Example 1> (Extrusion molding) Cycloolefin resin ARTON G7810 (JSR Corporation) was dried at 100°C for at least 2 hours and then melt-extruded at 280°C using a twin-screw kneading extruder. A screen filter, gear pump, and leaf disc filter were placed in this order between the extruder and the die, and these were connected by melt piping. The resin was extruded through a T-die with a width of 1000 mm and a lip gap of 1 mm and cast onto three cast rolls set at 180°C, 175°C, and 170°C, yielding unstretched film 1 with a width of 900 mm and a thickness of 320 μm.

[0108] (Stretching / heat setting) The unstretched film 1 being conveyed was subjected to a stretching step and a heat setting step by the following methods.

[0109] (a) Longitudinal stretching Unstretched Film 1 was longitudinally stretched under the following conditions while being conveyed using a roll-to-roll longitudinal stretching machine having an aspect ratio (L / W) of 0.2. <Condition> Preheat temperature: 170℃ Stretching temperature: 170℃ Stretching ratio: 155% (b) Lateral stretching The longitudinally stretched film was then transversely stretched under the following conditions while being transported using a tenter. <Condition> Preheat temperature: 170℃ Stretching temperature: 170℃ Stretching ratio: 80%

[0110] (c) Heat fixation Following the stretching process, the stretched film was heat-treated under the following conditions to be heat-set, while holding both ends of the stretched film by gripping the ends with tenter clips to maintain a constant width (within a range of expansion or contraction of 3%). Heat fixing temperature: 165℃ Heat setting time: 30 seconds The preheating temperature, stretching temperature and heat setting temperature are the average values ​​measured at five points in the width direction using a radiation thermometer.

[0111] (winding) After heat setting, both ends were trimmed and the film was taken up at a tension of 25 kg / m to obtain a film roll having a width of 1340 mm and a length of 2000 m. The obtained stretched film had Re of 275 nm, Rth of 192 nm, Nz coefficient of 1.2, slow axis in the TD direction, and film thickness of 68 μm, and was used as a λ / 2 retardation layer in a comparative example.

[0112] <Preparation of refractive index anisotropic layers in Examples 1 to 2, 6 to 9, and 11 to 13> (Fabrication of photo-alignment film) Coating solution 1 for photo-alignment film was prepared with reference to the description in Example 3 of JP-A No. 2012-155308. The previously prepared coating solution 1 for photoalignment film was applied to one side of a cellulose acetate film "Z-TAC" manufactured by Fujifilm Corporation using a bar coater. After application, the coating was dried on a hot plate at 120°C for 2 minutes to remove the solvent, forming a coating film. The resulting coating film was irradiated with polarized ultraviolet light (10 mJ / cm 2 A photo-alignment film 1 was formed by irradiating the liquid crystal with a liquid crystal display (using an ultra-high pressure mercury lamp).

[0113] (Formation of a refractive index anisotropic layer containing a rod-like liquid crystal compound) A liquid crystal layer forming composition 1 having the following composition was prepared. A liquid crystal layer-forming composition 1 was applied onto the photo-alignment film 1 using a bar coater to form a composition layer. The formed composition layer was heated to 110°C on a hot plate and then cooled to 60°C to stabilize the alignment. Thereafter, the composition layer was kept at 60°C and irradiated with ultraviolet light (500 mJ / cm) in a nitrogen atmosphere (oxygen concentration 100 ppm). 2 The alignment was fixed using an ultra-high pressure mercury lamp, and a refractive index anisotropic layer with a thickness of 3.5 μm and a 90° twist structure was prepared by adjusting the chiral agent. The refractive index anisotropic layer thus prepared had a Δnd of 450 nm (wavelength 550 nm). Similarly, a chiral agent was prepared to prepare a layer having an arbitrary refractive index anisotropy of 45 to 315° according to another embodiment.

[0114] ---------------------------------------------------------------------------------- (Liquid crystal layer forming composition 1) ---------------------------------------------------------------------------------- ·Liquid crystal compound R1 84.00 parts by mass ·Polymerizable compound B2 16.00 parts by mass Polymerization initiator P3 0.50 parts by mass Surfactant S3 0.15 parts by mass Chiral agent 0.1 parts by mass 2.00 parts by mass of Hisorb MTEM (manufactured by Toho Chemical Industry Co., Ltd.) NK Ester A-200 (manufactured by Shin-Nakamura Chemical Co., Ltd.) 1.00 parts by mass Methyl ethyl ketone 424.8 parts by mass ----------------------------------------------------------------------------------

[0115] ·Liquid crystal compound R1 [ka]

[0116] ·Polymerizable compound B2 [ka]

[0117] Polymerization initiator P3 [ka]

[0118] Surfactant S3 [ka]

[0119] Chiral agents [ka]

[0120] <Preparation of refractive index anisotropic layer of Example 10> <Preparation of a refractive index anisotropic layer having a twisted structure with reverse wavelength dispersion> A refractive index anisotropic layer having a reverse wavelength dispersion 90 twist structure was formed in the same manner as in the above-described liquid crystal layer forming composition 1, except that a liquid crystal layer forming composition 2 having the following formulation was used. The refractive index anisotropic layer thus produced had a Δnd of 350 nm (wavelength 550 nm).

[0121] ---------------------------------------------------------------------------------- (Liquid crystal layer forming composition 2) ---------------------------------------------------------------------------------- ·Liquid crystal compound R2 42.00 parts by mass ·Liquid crystal compound R3 42.00 parts by mass ·Polymerizable compound B2 16.00 parts by mass Polymerization initiator P3 0.50 parts by mass Surfactant S3 0.15 parts by mass Chiral agent 0.1 parts by mass 2.00 parts by mass of Hisorb MTEM (manufactured by Toho Chemical Industry Co., Ltd.) NK Ester A-200 (manufactured by Shin-Nakamura Chemical Co., Ltd.) 1.00 parts by mass Methyl ethyl ketone 424.8 parts by mass ----------------------------------------------------------------------------------

[0122] ·Liquid crystal compound R2 [ka]

[0123] ·Liquid crystal compound R3 [ka]

[0124] <Preparation of refractive index anisotropic layer of Example 3> The same alignment film PA1 as that used in producing the above-mentioned optically absorptive anisotropic layer was subjected to a rubbing treatment.

[0125] A liquid crystal layer-forming composition 3 containing a discotic liquid crystal compound of the following composition was applied to the alignment film prepared above using a wire bar. The coating solution was then heated with hot air at 120°C for 90 seconds to dry the solvent and ripen the alignment of the discotic liquid crystal compound. UV irradiation was then performed at 80°C to fix the alignment of the liquid crystal compound. In this way, a refractive index anisotropic layer with a 90° twist of the discotic liquid crystal was prepared. The refractive index anisotropic layer thus prepared had a Δnd of 350 nm (wavelength 550 nm).

[0126] ---------------------------------------------------------------------------------- (Liquid crystal layer forming composition 3) ---------------------------------------------------------------------------------- 91 parts by weight of the following discotic (discotic) liquid crystal compound: 5 parts by mass of the following acrylate monomer Photopolymerization initiator (Irgacure 907, manufactured by Ciba-Geigy) 3 parts by weight Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 1 part by mass 0.5 parts by mass of the following pyridinium salt Chiral agent 0.1 parts by mass 0.2 parts by mass of the following fluoropolymer (FP1) 0.1 parts by mass of the following fluoropolymer (FP3) Methyl ethyl ketone 189 parts by mass ----------------------------------------------------------------------------------

[0127] [ka]

[0128] Acrylate Monomers: Ethylene oxide modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.)

[0129] [ka]

[0130] <Switchable Optically Anisotropic Layer 1 of Example 4: Preparation of TN Liquid Crystal Cell> (Fabrication of TN mode liquid crystal cells) Two glass substrates with ITO electrodes were coated with a horizontally aligned polyimide alignment film and dried at high temperature to form the alignment film. The substrates were then rubbed to form a TN cell (in this example, the alignment was performed to create a 90° twist between the top and bottom). A thermosetting sealant was then applied to one of the two substrates, and spacer beads (5 μm diameter) were applied to the other. The two substrates were then bonded together, vacuum-packed, and heat-treated to form an empty liquid crystal cell. A liquid crystal with positive dielectric anisotropy, refractive index anisotropy Δn = 0.0854 (589 nm, 20°C), and Δε = +8.5 (MLC-9100 manufactured by Merck) was then injected into the cell using a vacuum liquid crystal injector. A TN liquid crystal cell with Δnd = 430 nm was then fabricated by sealing. Furthermore, because the inner surfaces of the upper and lower substrates are rubbed, the liquid crystal layer is twisted at a twist angle of 90° between the upper and lower substrates when no voltage is applied, and a TN cell has been completed in which the liquid crystal is oriented vertically when voltage is applied. Furthermore, by adjusting the spacer diameter, a liquid crystal cell with a twist structure of any Δnd can be formed.

[0131] <Example 5: Fabrication of Switchable Optically Anisotropic Layer 2: VATN Liquid Crystal Cell> (Electrically controllable refractive index anisotropy layer) Two glass substrates with ITO electrodes were coated with a vertically aligned polyimide alignment film and dried at high temperature to form the alignment film. The substrates were then rubbed to form a VATN cell (in this example, a 90° twist was achieved). A thermosetting sealant was then applied to one side of the two substrates, and spacer beads (5 μm diameter) were sprayed on the other. The two substrates were then bonded together, vacuum-packed, and heat-treated to form an empty liquid crystal cell. A liquid crystal with negative dielectric anisotropy, refractive index anisotropy Δn = 0.0899 (589 nm, 20°C), and Δε = -3.6 (MLC-6886, manufactured by Merck) was then injected into the cell using a vacuum liquid crystal injector. A VATN liquid crystal cell with Δnd = 450 nm was then fabricated after sealing. Furthermore, because the inner surfaces of the upper and lower substrates were rubbed, the liquid crystal layer was aligned vertically between the upper and lower substrates when no voltage was applied, and twisted at a 90° angle when voltage was applied. Moreover, by adjusting the spacer diameter, a liquid crystal cell with a twist structure of any Δnd can be formed.

[0132] [Preparation of optical laminate] The optically absorptive anisotropic layers prepared above were bonded to both sides of each of the various refractive index anisotropic layers prepared above using a commercially available pressure-sensitive adhesive SK2057 (manufactured by Soken Chemical & Engineering Co., Ltd.) to prepare the optical laminates of Examples 1 to 13 and Comparative Example 1. The thickness of SK2057 was approximately 20 μm.

[0133] [Preparation of viewing angle control systems of Examples 1 to 13] The liquid crystal display device of a Dynabook (manufactured by Toshiba Corporation), a notebook computer equipped with a liquid crystal display device, was disassembled, and various optical laminates prepared were bonded between the BL (backlight) and the liquid crystal panel using adhesive SK2057 to prepare an image display device. Similarly, the image display device of the present invention could also be realized by bonding various optical laminates to the viewing side of the liquid crystal display device of the above-mentioned notebook computer, dynabook (manufactured by Toshiba Corporation), using adhesive SK2057.

[0134] (Evaluation of the diagonal shading performance of the viewing angle control system) The image display devices fabricated in Examples 1 to 13 were all confirmed to have light-blocking properties in all directions, and observations confirmed that they were capable of excellent viewing angle control. On the other hand, the viewing angle control system of Comparative Example 1 blocked light at azimuth angles of every 90°, but did not block light in other directions. The brightness of the image display devices fabricated in the Examples and Comparative Examples was measured, and the ratio of the front brightness divided by the maximum oblique leakage light (all directions, polar angle 60°) was defined as the front / oblique brightness ratio, and the light-blocking performance was evaluated. The results are shown in Table 1. A higher value indicates better viewing angle control performance. For Examples 4 and 5, which can be electrically switched between security mode and wide viewing angle mode, the light-blocking performance was evaluated in security mode. Less than 3: Low viewing angle control effect: C 3~4: sufficient viewing angle control effect: B 4~5: Good viewing angle control effect: A 5 or above has excellent viewing angle control effect: AA

[0135] As shown in Table 1, the image display device of the present invention had better oblique light blocking performance than Comparative Example 1.

[0136] (Moire evaluation) The produced optical laminate was attached to the liquid crystal display device of an iPhone (registered trademark) 8 Plus smartphone manufactured by Apple Inc., and moire was evaluated. The iPhone (registered trademark) 8 Plus is a smartphone equipped with a high-definition liquid crystal display device, and the pixel density of the liquid crystal display device was 401 ppi. A black and white stripe pattern, in which white and black alternate for every pixel in the vertical direction, was displayed on this liquid crystal display device, and the device was observed from the front to visually evaluate moire. Since none of the optical laminates of Examples 1 to 13 and Comparative Example 1 had a periodic structure that interferes with the pixels of the image display device, no moire was visible and they had good display performance from the front. A louver film (commercially available product) such as that described in Patent Document 3 generated a striped pattern known as moire.

[0137] [Table 1]

[0138] As shown in Table 1, the optical laminate and image display device of the present invention had good oblique light blocking performance, no moire occurred, and had good display performance when viewed from the front. Furthermore, the optical laminates of the present invention (Examples 1 to 3 and 6 to 13) all had a thickness of 150 μm or less and were easy to fold. However, the louver film described in Patent Document 3 had a thickness of 500 μm and was difficult to fold.

[0139] It was confirmed that peeping prevention can be achieved by placing the optical laminate of the present invention on a window glass surface. It was also found that placing the optical laminate of the present invention on a glass surface onto which sunlight is incident makes it possible to control sunlight, thereby reducing the power consumption of air conditioners in the summer. It was also found that the same effect can be obtained when applied to vehicle windows. [Explanation of symbols]

[0140] 1 Front viewing direction 2. Diagonal viewing direction 11, 21 Absorption axis 101a Optically absorbing anisotropic layer 101b Polarizer layer 102 Refractive index anisotropic layer (having a twisted structure) 102c Liquid crystal cell (with twisted structure) 200 Display device 300 liquid crystal cells 301 Liquid crystal layer 302a Polarizing plate (viewing side) 302b Polarizing plate (light source side) 400 area light source 500 retardation layer

Claims

1. The liquid crystal display device has at least a first optically absorptive anisotropic layer, one or more refractive index anisotropic layers containing a liquid crystal compound having a twist structure, and a second optically absorptive anisotropic layer in this order, an optical laminate, wherein the first optically absorptive anisotropic layer and the second optically absorptive anisotropic layer contain an anisotropic absorbing material, a polymer liquid crystalline compound, the following compound E-1, and the following compound E-2, and the absorption axes are oriented at an angle of 60 degrees to 90 degrees with respect to the film surface. Compound E-1 【Chemical 1】 Compound E-2 【Chemistry 2】

2. 2. The optical laminate according to claim 1, wherein the absorption axes of the first optically absorptive anisotropic layer and the second optically absorptive anisotropic layer are oriented at an angle of 80 degrees to 90 degrees with respect to the film surface.

3. 3. The optical laminate according to claim 1, wherein the twist angle of the refractive index anisotropic layer having a twist structure satisfies formula I. 135·(2n−1) ≧ twist angle (degrees) ≧ 45·(2n−1) Formula I In the formula I, n represents a natural number.

4. An optical laminate according to any one of claims 1 to 3, comprising a first substrate and a second substrate arranged on each side of the refractive index anisotropic layer, at least one of which has a transparent electrode, the refractive index anisotropic layer being a liquid crystal cell, and the refractive index anisotropic layer, the first substrate and the second substrate constituting a liquid crystal panel capable of electrically switching birefringence.

5. 5. The optical laminate according to claim 4, wherein the liquid crystal cell is a TN liquid crystal cell capable of electrically switching birefringence or a VATN liquid crystal cell that exhibits a twisted structure when a voltage is applied.

6. The optical laminate according to any one of claims 1 to 3, wherein the refractive index anisotropic layer is formed by polymerizing a composition containing a discotic liquid crystalline compound or a rod-shaped liquid crystalline compound fixed in a state of twist orientation in the film thickness direction.

7. 7. The optical laminate according to claim 1, wherein the anisotropic absorbing material is a dichroic material.

8. The optical laminate according to claim 7 , wherein the dichroic material is any one of a dichroic dye, a carbon nanotube, and anisotropic metal nanoparticles.

9. 9. The optical laminate according to claim 7, wherein the first optically absorptive anisotropic layer and the second optically absorptive anisotropic layer each contain a liquid crystalline compound and at least one dichroic substance oriented perpendicular to the film surface.

10. The optical laminate according to claim 8 , wherein the material of the anisotropic metal nanoparticles is at least one selected from the group consisting of gold, silver, copper, and aluminum.

11. The optical laminate according to any one of claims 1 to 10, wherein a polarizer in which a liquid crystal compound and a dichroic substance are oriented horizontally to a film surface is laminated on one or both of the first optically absorptive anisotropic layer and the second optically absorptive anisotropic layer.

12. An image display device having the optical laminate according to any one of claims 1 to 11 disposed on the front surface thereof.

13. An image display device in which the optical laminate according to any one of claims 1 to 11 is disposed between a liquid crystal cell and a backlight source.

14. 12. An image display device comprising, in this order, the optical laminate according to claim 1, a retardation layer, and a polarizer whose absorption axis is oriented horizontally to the film surface.

15. 15. The image display device according to claim 12, wherein the display surface is a curved surface.

16. A glass composite comprising at least glass and the optical laminate according to any one of claims 1 to 11.

17. A glass composite which is a laminated glass having an intermediate layer between two glass plates, wherein the intermediate layer comprises the optical laminate according to any one of claims 1 to 11.

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