Optical laminate, image display device, and glass composite

Abstract

To provide an optical laminate, an image display device, and a glass composite which do not cause moire when used in combination with a high-definition image display device, and which can sufficiently block light emitted toward a direction inclined from the normal direction of a thin film. The optical laminate has at least in order a first light-absorbing anisotropic layer, one or more refractive index anisotropic layers containing a liquid-crystalline compound having a twisted structure, and a second light-absorbing anisotropic layer, the first and second light-absorbing anisotropic layers containing an anisotropic absorbing material, the absorption axes of which are oriented at an angle of 60 to 90 degrees with respect to the film surface.

Description

Technical Field

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

[0002] Liquid crystal displays (LCDs) and organic EL displays are commonly used as monitors in smartphones and laptops. In recent years, as these devices have become thinner and lighter, making them more portable, their use has increased significantly in transportation such as trains and airplanes, as well as in public places like libraries and restaurants. Therefore, due to the need to protect personal and confidential information, there is a demand for technologies that prevent the content displayed on these devices from being viewed by others.

[0003] Furthermore, in recent years, image display devices have also been used as in-vehicle displays installed in automobiles. As in-vehicle displays have become larger, the light emitted from the display is reflected into the windshield and side windows, which can obstruct driving. Technology is needed to address this problem and prevent this reflection.

[0004] To prevent prying into liquid crystal display devices and control viewing angles, techniques are known for using anisotropic light-absorbing layers with an absorption axis in the thickness direction. For example, Patent Documents 1 and 2 propose a polarization element related to a viewing angle control system using a thin film containing a dichroic material, wherein the angle formed by the absorption axis and the normal to the surface of the thin film is 0 to 45°.

[0005] Furthermore, Patent Document 3 discloses a viewing angle control system that alternately arranges light-transmitting and light-absorbing regions within the surface of the film to restrict light emission in a direction tilted relative to the normal direction of the film. This viewing angle control system is commonly referred to as a louvered film.

[0006] Previous technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 4902516

[0009] Patent Document 2: International Publication No. 2018 / 079854

[0010] Patent Document 3: Japanese Patent No. 6345732

[0011] Patent Document 4: Japanese Patent Application Publication No. 2008-165201 Summary of the Invention

[0012] The technical problem to be solved by the invention

[0013] Regarding the louvered film described in Patent Document 3, since it can sufficiently block light emitted in a direction inclined relative to the normal direction of the film, it is generally used for the purpose of preventing peeping from laptops and the like, as well as preventing light from being reflected into the windshield and side windows of vehicle displays.

[0014] However, because the light-transmitting and light-absorbing areas of the louvered film are alternately stacked at intervals of about tens of micrometers, these periodic structures can interfere with the pixels of the image display device, sometimes resulting in a striped pattern known as moiré. In particular, the problem of moiré has become increasingly apparent in recent years due to the increasing resolution of pixels in image display devices.

[0015] Furthermore, since louvered films typically have a substrate layer made of polycarbonate film or the like, and a thickness of 300 μm or more, they are not easily bent. In recent years, there have been image display devices with curved display surfaces used in automotive displays and other image display devices, for which louvered films are difficult to apply.

[0016] Furthermore, since louvered films control the field of view in the vertical or horizontal direction, in order to achieve field of view control only in the front direction to prevent peeping from laptops and other devices, as well as to prevent reflections from the windshield and side windows of vehicle displays, two louvered films need to be overlapped in both directions. However, the decrease in display quality caused by reduced front brightness, moiré patterns, and image blurring has become a problem.

[0017] Regarding the viewing angle control system described in Patent Documents 1 and 2, since it does not have a periodic structure that interferes with the pixels of the image display device, it can be used without moiré patterns. Furthermore, in the viewing angle control system described in Patent Documents 1 and 2, the polarizer has a thickness of several to tens of μm, and even including other substrate layers, the overall thickness can be reduced, thus making it easy to follow curved surfaces.

[0018] However, according to the research of the inventors, the viewing angle control system described in Patent Documents 1 and 2 cannot sufficiently reduce the transmittance in the direction tilted relative to the normal direction of the thin film, and the light shielding of the tilted light is insufficient. Therefore, when used for purposes such as preventing peeping from laptops and preventing vehicle displays from being reflected in the windshield and side window glass, the light shielding performance is insufficient.

[0019] Furthermore, the viewing angle control system described in Patent Document 4 discloses a structure in which a λ / 2 phase difference layer is sandwiched between polarizers having a polarization axis in the vertical direction. However, according to the research of the inventors, even in the viewing angle control system described in Patent Document 4, it is not possible to sufficiently reduce the transmittance in the direction tilted relative to the normal direction of the thin film, and the light shielding of the tilted light is insufficient.

[0020] The present invention was made in view of the above circumstances, and its object is to provide an optical laminate, an image display device, and a glass composite that do not produce moiré patterns when used in combination with a high-definition image display device and can adequately block light emitted in a direction that is inclined to the normal direction of the thin film.

[0021] means for solving technical problems

[0022] The inventors conducted in-depth research and found that by combining an anisotropic layer containing a liquid crystal compound with a twisted structure and an anisotropic light-absorbing layer with an absorption axis 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, excellent field of view control can be achieved.

[0023] <1>

[0024] An optical laminate comprising at least, sequentially, a first light-absorbing anisotropic layer, one or more refractive index anisotropic layers containing a liquid crystal compound with a twisted structure, and a second light-absorbing anisotropic layer.

[0025] The aforementioned first and second anisotropic light-absorbing layers contain anisotropic absorbing materials, with the absorption axis oriented at an angle of 60 to 90 degrees relative to the film surface.

[0026] <2>

[0027] according to <1> The optical laminate, wherein,

[0028] In the aforementioned first and second anisotropic light absorption layers, the absorption axis is oriented at an angle of 80 to 90 degrees relative to the film surface.

[0029] <3>

[0030] according to <1> or <2> The optical laminate, wherein,

[0031] The twist angle of the refractive index anisotropic layer with the above-mentioned twisted structure satisfies Equation I.

[0032] 135·(2n-1)≥Twist Angle (degrees)≥45·(2n-1) Equation I

[0033] In the above formula I, n represents a natural number.

[0034] <4>

[0035] according to <1> to <3> In any one of the optical laminates, wherein,

[0036] The device comprises a first substrate and a second substrate respectively disposed on both sides of the aforementioned anisotropic refractive index layer, with at least one side having a transparent electrode. The anisotropic refractive index layer is a liquid crystal cell. The anisotropic refractive index layer, the first substrate, and the second substrate constitute a liquid crystal panel capable of electrically switching birefringence.

[0037] <5>

[0038] according to <4> The optical laminate, wherein,

[0039] The aforementioned liquid crystal unit is either a TN liquid crystal unit capable of electrically switching birefringence or a VATN liquid crystal unit exhibiting a twisted structure under applied voltage.

[0040] <6>

[0041] according to <1> to <3> In any one of the optical laminates, wherein,

[0042] The above-mentioned anisotropic refractive index layer polymer composition is formed, wherein the composition contains a disk-shaped liquid crystal compound or a rod-shaped liquid crystal compound fixed in a twisted orientation along the film thickness direction.

[0043] <7>

[0044] according to <1> to <6> In any one of the optical laminates, wherein,

[0045] The aforementioned anisotropic absorbing materials are dichroic substances.

[0046] <8>

[0047] according to <7> The optical laminate, wherein,

[0048] Dichroic substances can be any one of dichroic pigments, carbon nanotubes, and anisotropic metal nanoparticles.

[0049] <9>

[0050] according to <7> or <8> The optical laminate, wherein,

[0051] In the aforementioned first light-absorbing anisotropic layer and second light-absorbing anisotropic layer, the liquid crystal compound and at least one dichroic substance are oriented perpendicularly to the film surface.

[0052] <10>

[0053] according to <8> The optical laminate, wherein,

[0054] The materials of the aforementioned anisotropic metal nanoparticles are selected from at least one of gold, silver, copper and aluminum.

[0055] <11>

[0056] according to <1> to <10> In any one of the optical laminates, wherein,

[0057] The stacked liquid crystal compound and dichroic material are polarizers that are horizontally oriented relative to one or both of the first and second light-absorbing anisotropic layers.

[0058] <12>

[0059] An image display device, wherein,

[0060] <1> to <11> The optical laminate as described in any one of the above statements is disposed on the front surface.

[0061] <13>

[0062] An image display device, wherein,

[0063] <1> to <11> The optical laminate described in any one of the above statements is disposed between the liquid crystal cell and the backlight source.

[0064] <14>

[0065] An image display device comprising, in sequence:

[0066] <1> to <11> The optical laminate, phasor layer, and polarizer whose absorption axis is horizontally oriented relative to the film surface as described in any one of the following.

[0067] <15>

[0068] according to <12> to <14> The image display device according to any one of the following methods has a curved surface in the display portion.

[0069] <16>

[0070] A glass composite having at least glass, and <1> to <11> The optical laminate as described in any one of the following.

[0071] <17>

[0072] A glass composite comprising a laminated glass having an interlayer between two panes of glass, wherein the interlayer comprises <1> to <11> The optical laminate as described in any one of the following.

[0073] Invention Effects

[0074] According to the present invention, an optical laminate, an image display device, and a glass composite with high transmittance when viewed from the front and reduced transmittance in the tilt direction can be provided. Furthermore, in a preferred embodiment of the present invention, by replacing the liquid crystal compound with a twisted structure with a TN liquid crystal cell or a VATN liquid crystal cell, the refractive anisotropy of the liquid crystal layer can be electrically controlled, thereby providing an image display device capable of electrically controlling both narrow and wide field of view. Attached Figure Description

[0075] Figure 1 This is a schematic diagram illustrating a perspective control system based on existing technology.

[0076] Figure 2 This is a schematic diagram illustrating an example of an image display device having the optical laminate of the present invention.

[0077] Figure 3 This is a schematic diagram illustrating another example of an image display device having the optical laminate of the present invention.

[0078] Figure 4 This is a schematic diagram illustrating another example of an image display device having the optical laminate of the present invention.

[0079] Figure 5 This is a schematic diagram illustrating another example of an image display device having the optical laminate of the present invention.

[0080] Figure 6 This is a schematic diagram illustrating another example of an image display device having the optical laminate of the present invention.

[0081] Figure 7 This is a schematic diagram illustrating another example of an image display device having the optical laminate of the present invention. Detailed Implementation

[0082] The present invention will now be described in detail.

[0083] The description of the constituent elements described below is sometimes based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0084] In addition, in this specification, the numerical range represented by “~” refers to the range included by taking the values ​​recorded before and after “~” as the lower limit and upper limit values.

[0085] In this specification, "parallel" and "orthogonal" do not refer to strict parallelism and orthogonality, but rather to a range of ±5° from parallel or orthogonal. Furthermore, unless otherwise specified, the polar angle in this specification refers to the angle formed with the normal direction of the thin film.

[0086] Furthermore, in this specification, the concepts of liquid crystal compositions and liquid crystal compounds also include liquid crystal compositions and liquid crystal compounds that no longer exhibit liquid crystal properties due to curing or the like.

[0087] Furthermore, in this specification, each component may be used alone with one corresponding substance, or with two or more substances used together. Here, when two or more substances are used together for each component, unless otherwise specified, the content of that component refers to the total content of the substances used together.

[0088] Furthermore, in this specification, "(meth)acrylate" is a designation for "acrylate" or "methacrylate", "(meth)acrylic acid" is a designation for "acrylic acid" or "methacrylic acid", and "(meth)acryloyl" is a designation for "acryloyl" or "methacryloyl".

[0089] In this invention, refractive indices nx and ny are the in-plane refractive indices of the optical component. Generally, nx is the refractive index in the slow axis direction, and nv is the refractive index in the fast axis direction (i.e., the direction orthogonal to the slow axis). Furthermore, 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.) and a sodium lamp (λ = 589 nm) as the light source. Furthermore, in determining wavelength dependence, it can be measured using a multi-wavelength Abbe refractometer DR-M2 (manufactured by ATAGO CO., LTD.) in combination with an interference filter. Moreover, values ​​from various optical thin film catalogs can be used in the Polymer Handbook (JOHNWILEY & SONS, INC.).

[0090] In this specification, Re(λ) and Rth(λ) represent the in-plane phase difference and the thickness direction phase difference at wavelength λ, respectively, using refractive indices nx, ny and nz and film thickness d (μm) and expressed by the following equations (1) and (2).

[0091] Formula (1): Re(λ)=(nx-ny)×d×1000(nm)

[0092] Formula (2): Rth(λ)=((nx+ny) / 2-nz)×d×1000(nm)

[0093] Unless otherwise specified, the wavelength λ is set to 550nm.

[0094] Slow axis orientation, Re(λ), and Rth(λ) can be determined, for example, using an AxoScan OPMF-1 (manufactured by Opto Science, Inc.).

[0095] In this specification, Δnd represents the retardation of rod-shaped or disk-shaped liquid crystal compounds and TN or VATN liquid crystal cells with a twisted structure, and is expressed as the product of the thickness d of the liquid crystal layer and the birefringence Δn of the liquid crystal. Furthermore, the twist angle represents the angle by which the liquid crystal director of the anisotropic refractive index layer rotates on the upper and lower surfaces of the substrate.

[0096] Furthermore, if the anisotropic refractive index layer with a twisted structure in this invention satisfies the following formula, the effects of this invention can be obtained, and therefore it is preferred.

[0097] Equation (3): 200nm ≤ Δn·d ≤ 1500nm

[0098] Equation (4): 135·(2n-1)≥Twist Angle (degrees)≥45·(2n-1)

[0099] In equation (4) above, n represents a natural number.

[0100] Unless otherwise specified, the Δn coefficient is set to the value at a wavelength of 550nm.

[0101] Description of existing technology.

[0102] First, regarding the existing perspective control system described in Patent Document 1, the mechanism for controlling the perspective will be explained.

[0103] Figure 1 This is a cross-sectional view of an existing viewing angle control system, which is formed on a display device 200 such as a liquid crystal display, an organic EL display, and a μLED display by stacking a light-absorbing anisotropic layer 101a having an absorption axis 11 in the normal direction of a thin film and a second polarizer 101b having an absorption axis 21 in the in-plane direction of the thin film. Figure 1 As shown, when visually recognizing the viewing angle control system from the front 1 (i.e., the normal direction of the thin film), the absorption axis 11 becomes horizontal relative to the viewing direction, so the light absorption anisotropic layer 101a does not absorb light traveling in the viewing direction. Therefore, the existing viewing angle control system transmits light.

[0104] On the other hand, when visually identifying the existing viewing angle control system from the tilted orientation 2, since the orientation (depth direction of the paper) of the absorption axis 21 of the light absorption anisotropic layer 101a having an absorption axis 11 in the normal direction of the thin film and the second polarizer layer 101b having an absorption axis 21 in the in-plane direction of the thin film are orthogonal, no light is transmitted, so light does not leak laterally. Furthermore, when visually identifying the existing viewing angle control system from the vertical direction (depth direction of the paper; not shown), the orientation (depth direction of the paper) of the absorption axis 21 of the light absorption anisotropic layer 101a having an absorption axis 11 in the normal direction of the thin film and the second polarizer layer 101b having an absorption axis 21 in the in-plane direction of the thin film becomes parallel, thus transmitting light. Therefore, it is known that sufficient omnidirectional light-blocking cannot be obtained in the existing viewing angle control system, and thus sufficient light-blocking cannot be achieved.

[0105] This invention enables the realization of an optical laminate with high transmittance when viewed from the front and reduced transmittance in the tilt direction, as well as an image display device with a high degree of security by controlling the viewing angle from all tilt directions and preventing peeping. Furthermore, by replacing the liquid crystal compound with a twisted structure with a TN liquid crystal cell or a VATN liquid crystal cell, the refractive anisotropy of the liquid crystal layer can be electrically controlled, thereby enabling an image display device with electrically controllable field of view for both narrow and wide viewing angles.

[0106] (Basic structure of the optical laminate and image display device of the present invention)

[0107] Next, the mechanism for expanding the range of light-blocking angles in the optical laminate and image display device of the present invention will be described.

[0108] The inventors conducted further research and found that... Figure 2 As shown, by stacking a (optically active) refractive index anisotropic layer 102 with a 90° twisted structure between two light-absorbing anisotropic layers 101a having an absorption axis 11 in the normal direction of the thin film on a display device 200 such as a liquid crystal display, organic EL display, and μLED display, it is possible to block oblique light from all directions and achieve excellent field-of-view control. Furthermore, regarding the effects of the present invention, it has been found that not only can this be achieved using a rod-shaped liquid crystal compound fixed in a twisted orientation along the film thickness direction, but also using a disk-shaped liquid crystal. Moreover, it has been found that the 90° twisted structure is not limited to any structure that exhibits optical activity; more preferably, it is achieved by implementing a refractive index anisotropic layer with a twist angle satisfying the following formula I, which allows for light blocking in oblique directions and control of the field of view.

[0109] 135·(2n-1)≥Twist Angle (degrees)≥45·(2n-1) Equation I

[0110] In the above formula I, n represents a natural number.

[0111] Furthermore, the results of in-depth research conducted by the inventors, such as Figure 3 As shown, the anisotropic refractive index layer 102c uses a TN-type liquid crystal cell that can electrically control birefringence or a VATN-type liquid crystal cell that displays a twisted structure under applied voltage, as disclosed in Japanese Patent Application Laid-Open No. 10-123576. This enables an image display device that can electrically switch between a safe mode with high transmittance when viewed from the front and a wide field-angle mode with high transmittance in both the front and tilt directions, and allows for highly secure field-angle control.

[0112] In the optical laminate of the present invention, when viewed from a tilted direction (a certain polar angle direction) relative to the film surface, the absorption axes 11 of the two light-absorbing anisotropic layers 101a are parallel. The refractive index anisotropic layer 102 disposed between the two light-absorbing anisotropic layers 101a causes the polarization direction of the incident linearly polarized light to rotate approximately 90°. Therefore, linearly polarized light passing through one of the light-absorbing anisotropic layers 101a undergoes a polarization direction rotation of approximately 90° due to the refractive index anisotropic layer 102. Consequently, the polarization direction of the linearly polarized light rotated by the refractive index anisotropic layer 102 becomes approximately parallel to the direction of the absorption axis of the other light-absorbing anisotropic layer 101a, and is absorbed by the other light-absorbing anisotropic layer 101a. This blocks light from the tilted direction relative to the film surface. Here, the refractive index anisotropic layer 102 can rotate the incident light independently of the polarization direction of the linearly polarized light, thus enabling the blocking of tilted light in all directions.

[0113] As an optical element that rotates the polarization direction of linearly polarized light by 90°, a λ / 2 plate is known. However, since the λ / 2 plate only acts on linearly polarized light in a specific direction, although it can block oblique light in a specific orientation, it cannot block oblique light depending on the orientation. In contrast, in this invention, since a refractive index anisotropic layer with a twisted structure is used, it is possible to block oblique light in all directions.

[0114] (An example of an embodiment of the image display device of the present invention)

[0115] like Figure 4As shown, in a liquid crystal panel 300 consisting of a liquid crystal cell 301 and orthogonal Nicol polarizers 302a and 302b disposed above and below the liquid crystal cell 301, and in a liquid crystal display (IPS, VA, TN, etc.) consisting of a surface light source 400, an optical laminate of the present invention having a 90° twisted structure (optical rotation) refractive index anisotropic layer 102 is stacked between two light absorption anisotropic layers 101a having an absorption axis 11 in the normal direction of the thin film, between the liquid crystal panel 300 and the surface light source 400. This enables an image display device that can block oblique light from all directions.

[0116] (Another embodiment of the optical laminate and image display device of the present invention)

[0117] like Figure 5 As shown above, in the above Figure 4 In the structure, by using a TN-type liquid crystal cell with electrically controllable birefringence or a VATN-type liquid crystal cell that displays a twisted structure under applied voltage as disclosed in Japanese Patent Application Laid-Open No. 10-123576 on the aforementioned anisotropic refractive index layer, an image display device with highly secure field-angle control can be realized, which can electrically switch between a safe mode with high transmittance when viewed from the front and a wide field-angle mode with high transmittance in both the front and tilt directions.

[0118] That is, as a structure in which a first substrate and a second substrate are respectively disposed on both sides of the anisotropic refractive index layer, and at least one of the first substrate and the second substrate has a transparent electrode, a liquid crystal panel can be formed by the anisotropic refractive index layer, the first substrate and the second substrate.

[0119] (Another embodiment of the image display device of the present invention)

[0120] like Figure 6 As shown, by placing a 90° twisted (optically active) refractive index anisotropic layer 102 between two light-absorbing anisotropic layers 101a having an absorption axis 11 in the normal direction of the thin film on the visual recognition side of the liquid crystal panel 300 composed of liquid crystal cell 301 and orthogonal Nicol polarizers 302a, 302b disposed above and below the liquid crystal cell 301, and the liquid crystal display (IPS, VA, TN, etc.) composed of surface light source 400, the optical laminate of the present invention, which is stacked between two light-absorbing anisotropic layers 101a having an absorption axis 11 in the normal direction of the thin film, can realize an image display device capable of controlling the field of view angle to block oblique light from all directions.

[0121] (Another example of an embodiment of the optical laminate of the present invention)

[0122] The optical laminate of the present invention can be configured such that, relative to one or both of the first light-absorbing anisotropic layer and the second light-absorbing anisotropic layer, a liquid crystal compound and a dichroic material are stacked relative to the light-absorbing anisotropic layer (polarizer layer) with the film surface horizontally oriented.

[0123] By adopting this structure, the polarizer layer can be used as a polarizer in a liquid crystal panel. Furthermore, the polarizer layer can be used as an anti-reflective polarizer in organic EL displays or micro-LED displays. Thus, an image display device capable of controlling the field of view to block oblique light from all directions can be constructed.

[0124] Furthermore, when optical laminates are used in combination with image display devices, such as liquid crystal displays, the polarizer of the image display device can be used as the aforementioned polarizer layer if the image display device has a polarizer (polarizer).

[0125] (Another embodiment of the optical laminate and image display device of the present invention)

[0126] Figure 7 The example shown includes: a liquid crystal panel 300 composed of a liquid crystal cell 301 and orthogonal Nicol polarizers 302a and 302b disposed above and below the liquid crystal cell 301; and a liquid crystal display (IPS, VA, TN, etc.) composed of a surface light source 400; on the visual recognition side of the liquid crystal panel 300, an optical laminate of the present invention having a 90° twisted structure (optically active) refractive index anisotropic layer 102c is stacked between two light absorption anisotropic layers 101a having an absorption axis 11 in the normal direction of the thin film; and a phase difference layer 500 disposed between the optical laminate and the liquid crystal panel 300. That is, Figure 7 In the example shown, there are optical laminates, phase difference layers and polarizers in sequence.

[0127] When combining an optical laminate with a polarizer, it remains in a light-blocking state in a certain orientation. Therefore, as a refractive index anisotropic layer, when using the refractive index anisotropic layer 102c, which can electrically switch between a mode that reduces the transmittance in the tilt direction using a liquid crystal layer with electrically controllable birefringence and a wide field-view mode with high transmittance in the front and tilt directions, it remains in a light-blocking state in a certain orientation even in the wide field-view mode.

[0128] In contrast, by setting a phase difference layer between the optical stack and the polarizer, it is possible to suppress the constant blocking state in a certain orientation direction, and improve the transmittance in all tilt directions in the wide field of view mode.

[0129] As a retardation layer, a general λ / 4 retardation plate or an O-plate with the slow axis tilted relative to the film surface can be preferably used.

[0130] Hereinafter, the optical components that can be used in the optical laminate and image display device of the present invention will be described in detail.

[0131] (Anisotropic light absorption layer)

[0132] The first and second anisotropic light-absorbing layers (hereinafter collectively referred to as anisotropic light-absorbing layers) of this invention are characterized in that the direction of the absorption axis is at an angle of 60° or more and 90° or less relative to the film surface. The direction of the absorption axis of the anisotropic light-absorbing layer is approximately consistent with the direction of highest transmittance of the image display device.

[0133] For example, in cases where it is used to prevent peeping from an image display device, it is preferable to maximize the transmittance in the front direction. In this case, the absorption axis of the light-absorbing anisotropic layer is aligned with the normal direction of the thin film and is perpendicular to the film surface. From the viewpoint of maximizing the transmittance in the front direction, the absorption axis of the light-absorbing anisotropic layer is preferably oriented at an angle of 80 to 90 degrees relative to the film surface.

[0134] Furthermore, the absorption axis of the light-absorbing anisotropic layer can be in different directions depending on its position. For example, in a vehicle display where the display surface is curved, in order to prevent light emitted from any position from entering the windshield or the like, and to allow the driver to make appropriate visual recognition, it is preferable to adjust the direction of the absorption axis of the light-absorbing anisotropic layer accordingly to the curved surface.

[0135] The light-absorbing anisotropic layer of this invention can have at least one dichroic substance (pigment) oriented perpendicularly to the film surface. The light-absorbing anisotropic layer can contain multiple dichroic substances. For example, it preferably contains a cyan pigment that exhibits dichroism in the red wavelength region, a magenta pigment that exhibits dichroism in the green wavelength region, and a yellow pigment that exhibits dichroism in the blue wavelength region. By containing multiple dichroic substances, hues can be neutralized, resulting in a viewing angle control effect across the entire visible light wavelength range.

[0136] In addition, dichroic substances refer to substances that exhibit dichroism, which means that the absorbance differs depending on the polarization direction.

[0137] The orientation degree of the dichroic material at a wavelength of 550 nm is preferably 0.95 or higher. If the orientation degree of the dichroic material is 0.95 or higher, the transmittance in the direction of the absorption axis (i.e., the direction of non-transmitted light) can be improved. Furthermore, in terms of neutralizing hues, the orientation degree of the dichroic material at a wavelength of 420 nm is preferably 0.93 or higher.

[0138] There is no particular limitation on the thickness of the light-absorbing anisotropic layer, but from the viewpoint of flexibility, it is preferably 100 to 8000 nm, and more preferably 300 to 5000 nm.

[0139] [Dichroic substances]

[0140] The dichroic substances used in this invention are not particularly limited to any substance exhibiting dichroism, and examples include dichroic pigments, dichroic azo compounds, ultraviolet-absorbing substances, infrared-absorbing substances, nonlinear optical substances, carbon nanotubes, anisotropic metal nanoparticles, and inorganic substances. Dichroic azo pigment compounds are particularly preferred.

[0141] The dichroic azo dye compound used in this invention is not particularly limited, and any existing known dichroic azo dye can be used. The dichroic azo dye compound may or may not exhibit liquid crystal properties. When the dichroic azo dye compound exhibits liquid crystal properties, 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 viewpoint of operability and manufacturing suitability.

[0142] In this invention, from the viewpoint of improving compressive strength, it is preferable that the dichroic azo dye compound has a crosslinking group. Specifically, examples of crosslinking groups include (meth)acryloyl, epoxy, oxetyl, and styrene groups, with (meth)acryloyl being preferred.

[0143] When the dichroic material is anisotropic metal nanoparticles, the preferred material for the anisotropic metal nanoparticles is selected from at least one of gold, silver, copper and aluminum.

[0144] [Liquid crystal compounds]

[0145] Anisotropic light-absorbing layers can contain liquid crystal compounds. By including liquid crystal compounds, it is possible to suppress the precipitation of dichroic substances while simultaneously aligning them with a high degree of orientation.

[0146] As a liquid crystal compound, either a low-molecular-weight liquid crystal compound or a high-molecular-weight liquid crystal compound can be used, and preferably both. Here, "low-molecular-weight liquid crystal compound" refers to a liquid crystal compound that does not have repeating units in its chemical structure. Here, "high-molecular-weight liquid crystal compound" refers to a liquid crystal compound that has repeating units in its chemical structure.

[0147] The low-molecular-weight liquid crystal compound can be either a compound exhibiting nematic liquid crystal properties or a compound exhibiting smectic liquid crystal properties, but from the viewpoint of high orientation, a compound exhibiting smectic liquid crystal properties is preferred. For example, the liquid crystal compound described in Japanese Patent Application Publication No. 2013-228706 can be cited.

[0148] As a polymeric liquid crystal compound, for example, the thermotropic liquid crystal polymer described in Japanese Patent Application Publication No. 2011-237513 can be cited. Furthermore, from the viewpoint of excellent strength (especially the bending resistance of the film), the polymeric liquid crystal compound preferably has repeating units with crosslinking groups at the ends. As crosslinking groups, for example, the polymeric groups described in paragraphs

[0040] to

[0050] of Japanese Patent Application Publication No. 2010-244038 can be cited. Among these, from the viewpoint of improving reactivity and synthetic applicability, acryloyl, methacryl, epoxy, oxetyl, and styrene groups are preferred, and acryloyl and methacryl are more preferred.

[0149] When the light-absorbing anisotropic layer contains a polymeric liquid crystal compound, the polymeric liquid crystal compound preferably forms a nematic liquid crystal phase. The temperature range for displaying the nematic liquid crystal phase is preferably room temperature (23°C) to 450°C, and from the viewpoint of processing or manufacturing suitability, it is preferably 50°C to 400°C.

[0150] Relative to 100 parts by mass of the dichroic material, the content of the liquid crystal compound in the light-absorbing 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. By keeping the content of the liquid crystal compound within the above range, the orientation degree of the dichroic material is further improved.

[0151] The liquid crystal compound may contain one or more liquid crystal compounds. When there are two or more liquid crystal compounds, the content of the liquid crystal compound mentioned above refers to the total content of the liquid crystal compounds.

[0152] [additive]

[0153] The light-absorbing anisotropic layer may also contain additives such as solvents, vertical alignment agents, surface modifiers, leveling agents, polymerizable components, polymerization initiators (e.g., free radical polymerization initiators), and durability modifiers. Well-known additives can be appropriately used.

[0154] [Substrate Layer]

[0155] Anisotropic light-absorbing layers can also have a substrate layer.

[0156] There are no particular limitations on the substrate layer, but a transparent film or sheet is preferred. Known transparent resin films, transparent resin sheets, transparent resin films, glass, etc., can be used. As a transparent resin film, cellulose acylated films (e.g., cellulose triacetate films, cellulose diacetate films, cellulose acetate butyrate films, cellulose acetate propionate films), polyethylene terephthalate films, polyethersulfone films, polyacrylic acid resin films, polyurethane resin films, polyester films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films, polyetherketone films, (meth)acrylonitrile films, etc., can be used.

[0157] Among them, cellulose acylated films with high transparency, low optical birefringence, easy manufacturing, and commonly used as protective films for polarizers are preferred, and cellulose triacetate films are particularly preferred.

[0158] The thickness of the transparent substrate film is preferably 20μm to 100μm.

[0159] [Orientation film]

[0160] An anisotropic light absorption layer may have an alignment film between the substrate layer and the anisotropic light absorption layer.

[0161] Regarding alignment films, any layer can be used as long as the dichroic material (liquid crystal compound) can be aligned to the desired state on the alignment film.

[0162] For example, films formed from polyfunctional acrylate compounds or polyvinyl alcohol can be used. Polyvinyl alcohol is particularly preferred.

[0163] By irradiating UV light from an inclined direction relative to a photo-aligned film such as an azo compound or cinnamic yl compound, the absorption axis can be tilted relative to the normal direction of the film.

[0164] [Blocking Layer]

[0165] The optical anisotropy layer preferably has a blocking layer.

[0166] Here, the barrier layer is also called the gas barrier layer (oxygen barrier layer), which has the function of protecting the light absorption anisotropy layer from the influence of gases such as oxygen in the atmosphere, moisture, or compounds contained in adjacent layers.

[0167] Regarding the barrier layer, for example, reference can be made to paragraphs

[0014] to

[0054] of Japanese Patent Application Publication No. 2014-159124, paragraphs

[0042] to

[0075] of Japanese Patent Application Publication No. 2017-121721, paragraphs

[0045] to

[0054] of Japanese Patent Application Publication No. 2017-115076, paragraphs

[0010] to

[0061] of Japanese Patent Application Publication No. 2012-213938, and paragraphs

[0021] to

[0031] of Japanese Patent Application Publication No. 2005-169994.

[0168] [Refractive index adjustment layer]

[0169] Regarding the light-absorbing anisotropic layer, which is a dichroic material, internal reflection caused by the high refractive index of the light-absorbing anisotropic layer can sometimes become a problem. In this case, it is preferable to have a refractive index adjustment layer on the optical laminate. The refractive index adjustment layer is configured to contact the light-absorbing anisotropic layer and is used for so-called refractive index matching. The in-plane average refractive index at a wavelength of 550 nm is preferably 1.55 or higher and 1.70 or lower.

[0170] [Methods for forming anisotropic light absorption layers]

[0171] There is no particular limitation on the method for forming the light-absorbing anisotropic layer. For example, a method can be described that includes the following steps in sequence: a step of forming a coating film by coating a light-absorbing anisotropic layer composition (hereinafter also referred to as the "coating film forming step"); and a step of aligning the liquid crystal component or dichroic substance included in the coating film (hereinafter also referred to as the "alignment step").

[0172] In addition, the liquid crystal component is as follows: it not only includes the liquid crystal compound mentioned above, but also, in the case that the dichroic substance has liquid crystal properties, it includes a dichroic substance that has liquid crystal properties.

[0173] [Coating film formation process]

[0174] The coating film forming process is a process of forming a coating film by coating a light-absorbing anisotropic layer composition.

[0175] By using a light-absorbing anisotropic layer forming composition containing a solvent or by using a light-absorbing anisotropic layer forming composition that has been molten into a liquid state by heating or the like, the light-absorbing anisotropic layer forming composition can be easily coated.

[0176] As a coating method for the composition for forming anisotropic light absorption layers, examples include known methods such as roller coating, gravure printing, spin coating, wire-wound bar coating, extrusion coating, direct gravure coating, reverse gravure coating, die coating, spray coating, and inkjet coating.

[0177] [Orientation Process]

[0178] The alignment process is the process of orienting the liquid crystal components contained in the coated film. As a result, an anisotropic light absorption layer can be obtained.

[0179] The orientation process may include a drying process. This drying process removes components such as solvents from the coated film. The drying process can be performed by placing the coated film at room temperature for a specified time (e.g., natural drying), or by heating and / or air supply.

[0180] Here, the liquid crystal components contained in the composition for forming anisotropic light absorption layers are sometimes oriented through the above-described coating film forming process or drying process. For example, in the case where the composition for forming anisotropic light absorption layers is prepared as a coating liquid containing a solvent, the solvent is removed from the coating film by drying the coating film, thereby obtaining a coating film with light absorption anisotropy (i.e., a light absorption anisotropic film).

[0181] If the drying process is performed at a temperature above the temperature at which the liquid crystal components contained in the coated film transform from a liquid crystal phase to an isotropic phase, the heating process described later may not be necessary.

[0182] From the perspective of manufacturing applicability, the transition temperature of the liquid crystal component contained in the coating film from the liquid crystal phase to the isotropic phase is preferably 10 to 250°C, more preferably 25 to 190°C. If the transition temperature is 10°C or higher, cooling treatment to lower the temperature to the liquid crystal phase range is not required, which is therefore preferable. Furthermore, if the transition temperature is 250°C or lower, high temperature is not required when heating to the isotropic phase for the purpose of suppressing alignment defects, and heat waste, substrate deformation, and deterioration are reduced, which is also preferable.

[0183] The alignment process preferably includes a heat treatment. This allows the liquid crystal components contained in the coated film to be aligned, thus enabling the heat-treated coated film to be preferably used as a light-absorbing anisotropic film.

[0184] From the perspective of manufacturing applicability, the heat treatment is preferably 10–250°C, more preferably 25–190°C. Furthermore, the heating time is preferably 1–300 seconds, more preferably 1–60 seconds.

[0185] The alignment process can include a cooling process performed after the heat treatment. The cooling process involves cooling the heated coating film to approximately room temperature (20–25°C). This helps to fix the alignment of the liquid crystal components contained in the coating film. There are no particular limitations on the cooling method; known methods can be used.

[0186] [Other processes]

[0187] The method for forming the light-absorbing anisotropic layer may include a step of curing the light-absorbing anisotropic layer (hereinafter also referred to as the "curing step") after the orientation step described above.

[0188] For example, when the light-absorbing anisotropic layer has cross-linking groups (polymeric groups), the curing process is carried out by heating and / or light irradiation (exposure). From a productivity point of view, it is preferable to carry out the curing process by light irradiation.

[0189] The light source used for curing can be various types of light sources such as infrared, visible light, or ultraviolet light, but ultraviolet light is preferred. Furthermore, during curing, ultraviolet light can be irradiated while heating is being performed, or ultraviolet light can be irradiated through a filter that transmits only a specific wavelength.

[0190] When exposure is performed while heating, although the heating temperature during exposure also depends on the transition temperature of the liquid crystal components contained in the liquid crystal film, it is preferably 25 to 140°C.

[0191] Furthermore, exposure can also be performed in a nitrogen environment. When curing liquid crystal films via free radical polymerization, the polymerization hindrance caused by oxygen is reduced, therefore exposure in a nitrogen environment is preferred.

[0192] (Another form of light-absorbing anisotropic layer with an absorption axis in the vertical direction)

[0193] An anisotropic light-absorbing layer can be, for example, as described in Japanese Patent Application Publication No. 2013-541727, comprising a dichroic pigment and a guest-host liquid crystal material, capable of electrically driving the orientation direction of the dichroic pigment. In this case, it is preferable because it is possible to electrically switch between a state controlling the viewing angle and a state without limiting the viewing angle. Furthermore, it is also preferable that the direction of the absorption axis of the dichroic pigment can be electrically controlled.

[0194] (Anisotropic refractive index layer)

[0195] In this invention, the anisotropic refractive index layer is disposed between two anisotropic light-absorbing layers. The anisotropic refractive index layer consists of one or more layers, but in this invention, it is preferably composed of one or two layers. Furthermore, from the viewpoint of making the optical laminate or image display device thinner, the thickness of the anisotropic refractive index layer is preferably thinner without impairing optical characteristics, mechanical properties, and manufacturing applicability; specifically, it is preferably 1 to 150 μm, more preferably 1 to 70 μm, and even more preferably 1 to 30 μm.

[0196] From the viewpoint of ease of manufacture, the refractive index anisotropy layer with a twisted structure is preferably a thin film with a twisted structure formed by adding a chiral material to a rod-shaped or disk-shaped liquid crystal compound. Furthermore, in terms of thinness, it can be manufactured to be thinner than a retardation layer using a polymer. On the other hand, when using polymer films, in order to obtain the twisted structure and optical rotation, it is difficult to manufacture multiple polymer films by gradually changing the angle of the slow axis of the polymer film in-plane and bonding them together. However, as polymer films, cellulose acylated films, cyclic olefin polymer films (polymer films using cyclic olefin polymers), polycarbonate polymer films, polystyrene polymer films, or acrylic polymer films are preferred. As an acrylic polymer film, it is preferable to include an acrylic polymer comprising at least one unit selected from lactone ring units, maleic anhydride units, and glutaric anhydride units.

[0197] [Using anisotropic layers with refractive indexes of liquid crystal compounds]

[0198] As an anisotropic refractive index layer formed using a liquid crystal compound, a thin film in which the liquid crystal compound is immobilized in a twisted orientation is preferred. More preferably, a thin film is obtained by coating a composition containing a liquid crystal compound having polymerizable groups to form a coating film, orienting the liquid crystal compound in the coating film, and then immobilizing the orientation of the liquid crystal compound by performing a curing treatment.

[0199] Examples of liquid crystal compounds include rod-shaped and (disc-shaped) liquid crystal compounds. To immobilize the orientation state, compounds with polymerizable groups are preferred. Furthermore, orientation at a target twist angle can be achieved by adjusting the amount of chiral agent added. Additionally, the use of a phase retardation layer with a liquid crystal compound facilitates thinning, and the thickness can easily be set to 10 μm or less.

[0200] <Liquid Crystal Compounds>

[0201] Examples of liquid crystal compounds include rod-shaped liquid crystal compounds and disc-shaped liquid crystal compounds.

[0202] As rod-shaped liquid crystal compounds, methylimine derivatives, azo derivatives, cyanobiphenyl derivatives, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexane derivatives, cyano-substituted phenylpyrimidine derivatives, alkoxy-substituted phenylpyrimidine derivatives, phenyl dioxane derivatives, diphenylacetylene derivatives, and alkenylcyclohexylbenzyl nitrile derivatives are preferred. Not only low-molecular-weight liquid crystal molecules as described above, but also high-molecular-weight liquid crystal molecules can be used.

[0203] More preferably, the orientation of the fixed rod-shaped liquid crystal compound is obtained through polymerization. As a polymerizable rod-shaped liquid crystal compound, it can be used in Makromol. Chem., Vol. 190, pp. 2255 (1989), Advanced Materials. Compounds described in 5 volumes, 107 pages (1993), U.S. Patent No. 4,683,327, U.S. Patent No. 5,622,648, U.S. Patent No. 5,770,107, WO95 / 22,586, WO95 / 24,455, WO97 / 00600, WO98 / 23,580, WO98 / 52,905, Japanese Patent Application Publication No. 1-272,551, Japanese Patent Application Publication No. 6-16,616, Japanese Patent Application Publication No. 7-110,469, Japanese Patent Application Publication No. 11-80081, and Japanese Patent Application No. 2001-64,627. Furthermore, as a rod-shaped liquid crystal compound, the rod-shaped liquid crystal compound described in Japanese Patent Application Publication No. 11-513019 or Japanese Patent Application Publication No. 2007-279688 can be preferred.

[0204] As a disc-shaped liquid crystal compound, for example, the disc-shaped liquid crystal compound described in Japanese Patent Application Publication No. 2007-108732 or Japanese Patent Application Publication No. 2010-244038 can be preferred, but it is not limited thereto.

[0205] The following shows preferred examples of disk-shaped liquid crystal compounds, but the present invention is not limited to these.

[0206] [Chemical Formula 1]

[0207] Compound 1

[0208]

[0209] Compound 2

[0210]

[0211] Compound 101

[0212]

[0213] Compound 102

[0214]

[0215] Chiral reagents

[0216] Chiral agents are compounds used to adjust the helical period of cholesterol-type liquid crystal compounds, also known as chiral agents. In this invention, various known chiral agents can be used (e.g., Liquid Crystal Device Handbook, Chapter 3, Items 4-3, TN, STN with chiral agents, page 199, compiled by the 142nd Committee of the Japan Society for the Promotion of Science, recorded in 1989). Chiral agents generally contain asymmetric carbon atoms, but axially asymmetric compounds or surface asymmetric compounds that do not contain asymmetric carbon atoms can also be used as chiral agents. Examples of axially asymmetric compounds or surface asymmetric compounds include naphthalene, helicene, p-cycloaranes, and their derivatives. Chiral agents can have polymerizable groups. When a chiral agent has polymerizable groups and a rod-shaped liquid crystal compound also has polymerizable groups is used in conjunction with it, a polymer having repeating units derived from the rod-shaped liquid crystal compound and repeating units derived from the chiral agent can be formed through a polymerization reaction between the chiral agent with polymerizable groups and the polymerizable rod-shaped liquid crystal compound. In this manner, the chiral reagent having polymerizable groups preferably possesses polymerizable groups of the same type as those possessed by the polymerizable rod-shaped liquid crystal compound. Therefore, the polymerizable groups of the chiral reagent are preferably unsaturated polymerizable groups, epoxy groups, or aziridinyl groups, more preferably unsaturated polymerizable groups, and particularly preferably vinyl unsaturated polymerizable groups.

[0217] Furthermore, the aforementioned chiral reagent can be a liquid crystal compound.

[0218] Chiral reagents exhibiting strong torsional forces, for example, those described in Japanese Patent Application Publication Nos. 2010-181852, 2003-287623, 2002-80851, 2002-80478, and 2002-302487, are preferably used in this invention. Furthermore, isomannitol compounds with corresponding structures can be used for the isomannitol compounds described in these publications.

[0219] As a liquid crystal compound, a liquid crystal compound exhibiting anti-dispersion wavelength dispersion is preferred. For example, a liquid crystal compound exhibiting anti-dispersion wavelength dispersion described in brochure WO2017 / 043438 can be cited. In a viewing angle control system, a refractive index anisotropic layer (phase retardation layer) using a liquid crystal compound exhibiting anti-dispersion wavelength dispersion can provide optical compensation throughout the entire visible light wavelength range.

[0220] Here, the wavelength dispersion of inverse dispersion refers to the values ​​of Re(λ) and Rth(λ) that increase as the wavelength λ increases.

[0221] In the case where the anisotropic refractive index layer is a phase difference film formed using a liquid crystal compound, an alignment film may also be present. The alignment film is typically composed mainly of a polymer. Polymer materials for alignment films are described in numerous documents, and many commercially available products are readily available. The polymer material used is preferably polyvinyl alcohol or polyimide and its derivatives. Modified or unmodified polyvinyl alcohol is particularly preferred. Regarding the alignment film that can be used in this invention, reference can be made to modified polyvinyl alcohol, etc., described on page 43, lines 24 to 49, lines 8 of Japanese Patent Publication No. WO01 / 88574A1 and in paragraphs

[0071] to

[0095] of Japanese Patent Publication No. 3907735. Furthermore, the aforementioned alignment film is typically subjected to a known rubbing treatment.

[0222] The thickness of the alignment film is preferably thin, but from the viewpoint of imparting orientation energy for forming the anisotropic refractive index layer and mitigating surface irregularities of the film to form a uniformly thick anisotropic refractive index layer, a certain thickness is required. 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.

[0223] Furthermore, in this invention, a photoalignment film is preferably used. There are no particular limitations on the photoalignment film; the photoalignment film described in paragraphs

[0024] to

[0043] of WO2005 / 096041 or the product manufactured by Rolic Technologies Ltd. under the trade name LPP-JP265CP is preferred.

[0224] [Using anisotropic layers of polymer thin films]

[0225] When using a phase difference layer obtained by stretching a polymer film in an anisotropic refractive index environment, it 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) manufactured by suitable methods such as melt film formation and solution film formation, for example, by stretching it using a longitudinal stretching method based on roller circumferential speed control, a transverse stretching method based on a tenter frame, and a biaxial stretching method. More specifically, refer to the description in Japanese Patent Application Publication No. 2005-338767.

[0226] Furthermore, as described in, for example, Japanese Patent Application Publication No. 5-157911, Japanese Patent Application Publication No. 2006-72309, or Japanese Patent Application Publication No. 2007-298960, it is also possible to manufacture the polymer film by stretching it along the thickness (nz) direction by laminating a shrinkable film onto one or both sides of the polymer film and then heating and stretching it.

[0227] Polymer films are preferably used, for example, to fabricate B-plates. In order to fabricate an anisotropic layer with a negative Nz coefficient, polymer films exhibiting negative intrinsic birefringence are preferred. For example, films using a mixture of methyl methacrylate-methyl acrylate copolymer and styrene-maleic anhydride copolymer, as described in Example 19 of Japanese Patent Application Publication No. 2008-262182, can be used.

[0228] As a polymer film, a polymer film exhibiting anti-dispersion wavelength dispersion is preferred. Modified polycarbonate films are known, for example, as polymer films exhibiting anti-dispersion wavelength dispersion.

[0229] (Anisotropic layer with electrically controllable refractive index)

[0230] When the anisotropic refractive index layer is the liquid crystal cell, a TN (Twisted Nematic) mode with a twisted structure is preferred, but it is not limited to this. The inventors have discovered that an STN (Super Twisted Nematic) mode with a twist angle of 180° or more can also achieve the effects of the present invention. In a TN mode liquid crystal cell, the rod-shaped liquid crystal molecules are substantially horizontally oriented when no voltage is applied, and then twisted at 60 to 120°. On the other hand, as disclosed in Japanese Patent Application Publication No. 10-123576, the inventors have discovered that by using a VATN (Vertically Aligned Twisted Nematic) mode liquid crystal in which the rod-shaped liquid crystal molecules are substantially vertically oriented when no voltage is applied, and the liquid crystal layer is twisted at 60 to 120° when a voltage is applied, the excellent field-of-view control of the present invention can be achieved.

[0231] (Optical laminate)

[0232] The optical laminate of the present invention can be constructed by combining two light-absorbing anisotropic layers and a refractive index anisotropic layer. Figure 2 This is achieved through [the following method]. In general liquid crystal display devices and organic EL display devices, most layers consist of polarizers having absorption axes in the in-plane direction of the display surface. Therefore, the optical laminate of the present invention can be subsequently bonded to polarizers already bonded to liquid crystal display devices and organic EL display devices to fabricate the image display device of the present invention, thus offering high convenience.

[0233] (Polarizer layer)

[0234] The polarizer layer in this invention can use a polarizer that is horizontally oriented to a general dichroic material, such that the direction of the absorption axis is horizontal to the surface of the thin film. For example, it can be a polarizer that is horizontally oriented by dyeing a dichroic material with polyvinyl alcohol or other polymer resins and stretching it, or it can be a polarizer that is horizontally oriented by utilizing the orientation of a liquid crystal compound, as in the light-absorbing anisotropic layer of this invention.

[0235] Polarizers made of stretched polyvinyl alcohol and dyed with iodine are generally used as polarizer layers in polarizers provided in liquid crystal display devices and organic EL display devices. Therefore, when the optical laminate of the present invention is used in liquid crystal display devices and organic EL display devices, the polarizers provided in the liquid crystal display devices and organic EL display devices can also serve as polarizer layers.

[0236] Furthermore, the polarizer layer can be a reflective polarizer or a stack of an absorption polarizer (a typical polarizer) and a reflective polarizer. A reflective polarizer is a polarizer that reflects one type of polarized light and transmits another type of polarized light. Additionally, a reflective polarizer has a reflection axis and a transmission axis in its plane, but in the sense that it does not transmit polarized light in its orientation, the reflection axis functions the same as the absorption axis in a typical polarizer. Therefore, in this specification, the reflection axis can be replaced with an absorption axis.

[0237] When the polarizer layer is a reflective polarizer, light that does not pass through the reflective polarizer will be reflected. Therefore, for example, when an optical laminate is assembled on the backlight side of a liquid crystal display device, the reflected light can be reused to improve the light utilization efficiency.

[0238] As a reflective polarizer, it is preferable to use 3M Company's brightness enhancement film "DBEF" or "APF", or Asahi Kasei Corporation's wire grid polarizing film "WGF".

[0239] The optical laminate of the present invention includes at least a first light-absorbing anisotropic layer having a polarization axis in the vertical direction, a refractive index anisotropic layer, and a second light-absorbing anisotropic layer having a polarization axis in the vertical direction, but may also include other functional layers. For example, it may include an adhesive layer, bonding layer, anti-reflective layer, or protective layer, etc.

[0240] The manufacturing method of an optical laminate may include the steps of separately fabricating anisotropic light-absorbing layers, anisotropic refractive index layers, and other functional layers, and bonding them together with adhesives or bonding agents.

[0241] Furthermore, for example, it may include a process of transferring a light-absorbing anisotropic layer formed on a substrate onto a refractive index anisotropic layer.

[0242] Furthermore, the process may include either directly coating a refractive index anisotropic layer onto a light-absorbing anisotropic layer, or forming a light-absorbing anisotropic layer directly onto the refractive index anisotropic layer after the refractive index anisotropic layer has been formed.

[0243] Each process can be carried out in accordance with known methods, and there are no particular limitations.

[0244] (Image display device)

[0245] The optical laminate of the present invention can be used in any image display device.

[0246] There are no particular limitations on what constitutes an image display device; for example, liquid crystal displays, organic EL displays, micro LED displays, head-up displays, and head-mounted displays can be cited.

[0247] like Figure 4 As shown, a liquid crystal display device typically includes a liquid crystal cell 301 and a backlight 400, and polarizers (302a, 302b) are respectively provided on the visual recognition side and the backlight side of the liquid crystal cell 301. The optical laminate of the present invention can be applied to the visual recognition side of the liquid crystal panel 300 ( Figure 6 ) or backlight side ( Figure 4 It can be applied to any one of the surfaces of the liquid crystal panel 300, or to two surfaces (not shown). Furthermore, it can also be applied by attaching the optical laminate of the present invention to the polarizers of any one or two surfaces of the liquid crystal panel 300.

[0248] When the optical laminate of the present invention is applied to a liquid crystal display device, from the viewpoint of improving the display performance of the liquid crystal display device, it is preferably disposed on the backlight side of the liquid crystal cell. Furthermore, when the optical laminate of the present invention is applied to the backlight side of the liquid crystal cell, from the viewpoint of improving light utilization efficiency, it is preferable that the polarizer layer of the liquid crystal cell is a reflective polarizer or a laminate of a conventional polarizer and a reflective polarizer.

[0249] In image display devices, there are thin devices that can be formed into curved surfaces. Since the optical laminate of the present invention is thin and easily bent, it is preferably suitable for image display devices with curved display surfaces.

[0250] Furthermore, image display devices also include those with a pixel density greater than 250 ppi and capable of high-definition display. The optical laminate of the present invention is also preferably suitable for such high-definition image display devices without moiré patterns.

[0251] [Liquid crystal unit for display device]

[0252] The liquid crystal cells used in the liquid crystal display device are preferably in VA (Vertical Alignment) mode, OCB (Optically Compensated Bend) mode, IPS (In-Plane-Switching) mode or TN (Twisted Nematic) mode, but are not limited to these.

[0253] In TN mode liquid crystal cells, bar-shaped liquid crystal molecules are substantially horizontally aligned when no voltage is applied, and twisted at 60–120°. TN mode liquid crystal cells are most commonly used in color TFT (Thin Film Transistor) liquid crystal display devices and are documented in many publications.

[0254] In a VA-mode liquid crystal cell, the rod-shaped liquid crystal molecules are substantially vertically oriented when no voltage is applied. In a VA-mode liquid crystal cell, in addition to (1) a narrow VA-mode liquid crystal cell in which the rod-shaped liquid crystal molecules are substantially vertically oriented when no voltage is applied and substantially horizontally oriented when a voltage is applied (as described in Japanese Patent Application Publication No. 2-176625), there are also (2) a liquid crystal cell in which the VA mode is multi-domained (MVA mode) in order to expand the field of view (as described in SID97, Digest of Tech Papers 28 (1997) 845), (3) a liquid crystal cell in which the rod-shaped liquid crystal molecules are substantially vertically oriented when no voltage is applied and twisted and multi-domain oriented when a voltage is applied (n-ASM mode) (as described in the proceedings of the Japan Liquid Crystal Conference 58-59 (1998)), and (4) a SURVIVAL mode liquid crystal cell (published in LCD International 98). Furthermore, it can be any of the following: PVA (Patterned Vertical Alignment), Optical Alignment, and PSA (Polymer-Sustained Alignment). Detailed information about these modes can be found in Japanese Patent Application Publication Nos. 2006-215326 and 2008-538819.

[0255] In an IPS-mode liquid crystal cell, rod-shaped liquid crystal molecules are substantially parallel to the substrate. By applying an electric field parallel to the substrate surface, the liquid crystal molecules respond in a planar manner. The IPS mode displays black when no electric field is applied, and the absorption axes of the upper and lower polarizers are orthogonal. Methods for reducing light leakage and improving the field of view when displaying black in the tilt direction using optical compensation plates are disclosed in Japanese Patent Application Publication Nos. 10-54982, 11-202323, 9-292522, 11-133408, 11-305217, and 10-307291.

[0256] [Organic EL display device]

[0257] As an example of the image display device of the present invention, an organic EL display device is preferably provided, for example, in which the optical laminate, the λ / 4 plate and the organic EL display panel of the present invention are sequentially arranged from the visual recognition side.

[0258] Furthermore, organic EL display panels are display panels constructed using organic EL elements formed by sandwiching an organic light-emitting layer (organic electroluminescent layer) between electrodes (between the cathode and the anode). There are no particular restrictions on the structure of organic EL display panels, and well-known structures can be used.

[0259] [Curved surface image display device]

[0260] Examples of curved image display devices of the present invention are disclosed in Japanese Patent Application Publication Nos. 2017-181821, 2017-181819, 2017-102456 and 2014-95901.

[0261] [Glass composite]

[0262] The optical laminate of the present invention can be combined with glass.

[0263] For example, by disposing the optical laminate of the present invention on the surface of a window glass, peeping can be prevented. Furthermore, by disposing the optical laminate of the present invention on the glass surface where sunlight enters, sunlight control can be achieved, and air conditioning power consumption in summer can be reduced. The same effect can also be obtained when applied to vehicle windows.

[0264] Furthermore, the glass composite can be a laminated glass with an intermediate layer between two glass plates, or it can be a structure that includes the optical laminate of the present invention as an intermediate layer.

[0265] Example

[0266] The following examples provide further detailed description of the present invention. The materials, reagents, quantities, proportions, and operations shown in the following examples can be appropriately modified without departing from the spirit of the invention. Therefore, the scope of the present invention is not limited to the specific examples below.

[0267] [Fabrication of anisotropic light absorption layers]

[0268] The light absorption anisotropic layer 101a used in the embodiments and comparative examples of the present invention is fabricated as follows.

[0269] <Fabrication of Transparent Support 1 with Orientation Membrane>

[0270] The surface of a cellulose acylated film (40 μm thick TAC substrate; TG40 FUJIFILM Corporation) was saponified in an alkaline solution, and an alignment layer forming coating solution 1 was applied to it by a winding bar. The cellulose acylated film with the coating was dried with warm air at 60°C for 60 seconds, and then dried with warm air at 100°C for 120 seconds to form the alignment layer PA1, thereby obtaining a transparent support 1 with an alignment layer.

[0271] The thickness of the orientation film PA1 is 0.5 μm.

[0272]

[0273] Modified polyvinyl alcohol

[0274] [Chemical Formula 2]

[0275]

[0276] <Examples 1-9, Formation of the light absorption anisotropic layer P1 in Comparative Example 1>

[0277] The following light-absorbing anisotropic layer forming composition 1 was continuously coated onto the obtained orientation layer PA1 using a winding bar to form a coating layer.

[0278] Next, the coating layer was heated at 140°C for 30 seconds, and then cooled to room temperature (23°C).

[0279] Next, heat at 80°C for 60 seconds and then cool to room temperature again.

[0280] Then, using an LED light (center wavelength 365nm) at an illuminance of 200mW / cm² 2 Irradiate for 2 seconds under the irradiation conditions, thereby creating an anisotropic light-absorbing layer P1 on the orientation layer PA1.

[0281] The thickness of the light-absorbing anisotropic layer P1 is 3 μm, and the orientation degree at 550 nm is 0.92. The light-absorbing anisotropic layer P1 with support obtained therefrom is designated as light-absorbing anisotropic layer 101a.

[0282] Furthermore, observations of the absorption axis of the light absorption anisotropic layer P1 revealed that the absorption axis is 90 degrees relative to the film surface.

[0283] <Determination of the Orientation Anisotropy Layer in Optical Absorption>

[0284] Using an Axometrics AxoScan OPMF-1 polarimeter, the fabricated anisotropic light-absorbing layer was horizontally placed on the sample stage. While changing the incident azimuth and polar angle, P-polarized light was incident on the surface of the anisotropic light-absorbing layer, and the transmittance was measured. The transmittance was then adjusted to the azimuth and polar angles that resulted in the maximum transmittance.

[0285] Furthermore, using a microtome, 2 μm thick slices were collected parallel to the azimuth angle where the transmittance is maximized and parallel to the plane containing the normal to the surface of the anisotropic light-absorbing layer. The collected slices were then inverted and placed on the rotating stage of a polarizing microscope. The azimuth angle (the angle at which the slice is rotated) of the slice with the lowest extinction relative to the cross-section of the anisotropic light-absorbing layer of the incident linearly polarized light was determined. In this way, the angle of the absorption axis of the anisotropic light-absorbing layer was measured.

[0286]

[0287]

[0288] Dichroic substance D-1

[0289] [Chemical Formula 3]

[0290]

[0291] Dichroic substance D-2

[0292] [Chemical Formula 4]

[0293]

[0294] Dichroic substance D-3

[0295] [Chemical Formula 5]

[0296]

[0297] P-1, a polymeric liquid crystal compound

[0298] [Chemical Formula 6]

[0299]

[0300] Low molecular weight liquid crystal compound M-1

[0301] [Chemical Formula 7]

[0302]

[0303] Compound E-1

[0304] [Chemical Formula 8]

[0305]

[0306] Compound E-2

[0307] [Chemical Formula 9]

[0308]

[0309] Surfactant F-1

[0310] [Chemical Formula 10]

[0311]

[0312] Surfactant F-2

[0313] [Chemical Formula 11]

[0314]

[0315] <Fabrication of the Light Absorption Anisotropic Layer in Example 10>

[0316] In Example 10, the following light absorption anisotropic layer forming composition 2 was used, and the light absorption anisotropic layer was formed in the same manner as the light absorption anisotropic layer P1.

[0317]

[0318]

[0319] <Fabrication of the Light Absorption Anisotropic Layer in Example 11>

[0320] In Example 11, the following light absorption anisotropic layer forming composition 3 was used, and the light absorption anisotropic layer was formed in the same manner as the light absorption anisotropic layer P1.

[0321]

[0322] <Fabrication of the Light Absorption Anisotropic Layer in Example 12>

[0323] In Example 12, the following light absorption anisotropic layer forming composition 4 was used, and the light absorption anisotropic layer was formed in the same manner as the light absorption anisotropic layer P1.

[0324]

[0325] <Fabrication of the Light Absorption Anisotropic Layer in Example 13>

[0326] In Example 13, the following light absorption anisotropic layer forming composition 5 was used, and the light absorption anisotropic layer was formed in the same manner as the light absorption anisotropic layer P1.

[0327]

[0328]

[0329] [Fabrication of anisotropic refractive index layers]

[0330] The following describes the various phase difference layers used in the embodiments of the present invention.

[0331] <Fabrication of the phase difference layer (λ / 2) in Comparative Example 1>

[0332] (Extrusion molding)

[0333] The cyclic olefin resin ARTON G7810 (JSR Corporation.) was dried at 100°C for more than 2 hours and then melt-extruded at 280°C using a two-roll compounding extruder. At this time, a screen filter, a gear pump, and a vane-type disc filter were sequentially arranged between the extruder and the die, and connected by melt piping. The film was extruded from a T-die with a width of 1000 mm and a lipgap of 1 mm, and cast onto a three-roll casting system set to 180°C, 175°C, and 170°C, thereby obtaining an unstretched film 1 with a width of 900 mm and a thickness of 320 μm.

[0334] (Stretching & Heat Setting)

[0335] The above-mentioned unstretched film 1, which is being transported, is subjected to a stretching process and a heat setting process using the following method.

[0336] (a) Longitudinal tension

[0337] For the unstretched film 1, longitudinal stretching was performed under the following conditions while being transported using a longitudinal stretching machine with an aspect ratio (L / W) of 0.2.

[0338] <Conditions>

[0339] Preheating temperature: 170℃

[0340] Tensile temperature: 170℃

[0341] Stretch ratio: 155%

[0342] (b) Lateral stretching

[0343] For longitudinally stretched films, transverse stretching was performed while transporting them using a tenter frame under the following conditions.

[0344] <Conditions>

[0345] Preheating temperature: 170℃

[0346] Tensile temperature: 170℃

[0347] Stretch ratio: 80%

[0348] (c) Heat setting

[0349] Following the stretching process, the stretched film is held at both ends by a tenter frame clamp and heat-treated under the following conditions while maintaining the width at both ends of the stretched film in a manner that is specified (enlargement or reduction within 3%), thereby achieving heat setting.

[0350] Heat setting temperature: 165℃

[0351] Heat setting time: 30 seconds

[0352] In addition, the preheating temperature, stretching temperature, and heat setting temperature are the average values ​​measured at 5 points in the width direction using a radiation thermometer.

[0353] (Roll-up)

[0354] After heat setting, the two ends are cut off and the roll is rolled with a tension of 25 kg / m to obtain a film roll with a width of 1340 mm and a roll length of 2000 m.

[0355] The resulting stretched film has a Re value of 275 nm, an Rth value of 192 nm, an Nz coefficient of 1.2, a slow axis along the TD direction, and a film thickness of 68 μm. It was used as a λ / 2 phase retardation layer for comparative examples.

[0356] <Fabrication of Refractive Index Anisotropic Layers in Examples 1-2, 6-9, and 11-13>

[0357] (Fabrication of photo-aligned film)

[0358] Referring to the description in Japanese Patent Application Publication No. 2012-155308 and Example 3, a coating liquid 1 for photo-alignment film was prepared.

[0359] On one side of a cellulose acetate film “Z-TAC” manufactured by FUJIFILM Corporation, a pre-prepared coating solution 1 for photoalignment film was applied using a rod coater. After coating, the solvent was removed by drying on a hot plate at 120°C for 2 minutes, thereby forming a coating film. The photoalignment film 1 was formed by irradiating the obtained coating film with polarized ultraviolet light (10 mJ / cm2 using an ultra-high pressure mercury lamp).

[0360] (Including the formation of anisotropic layers of refractive index of rod-shaped liquid crystal compounds)

[0361] Composition 1 for forming a liquid crystal layer with the following composition was prepared.

[0362] The liquid crystal layer forming composition 1 is coated onto the photoalignment film 1 using a rod coater, thereby forming a composition layer. The formed composition layer is heated to 110°C on a hot plate and then cooled to 60°C to stabilize the alignment. It is then maintained at 60°C and subjected to ultraviolet irradiation (500 mJ / cm²) in a nitrogen atmosphere (oxygen concentration 100 ppm). 2 Using an ultra-high pressure mercury lamp to fix the orientation, a 3.5 μm thick anisotropic refractive index layer with a 90° twisted structure was fabricated. The fabricated anisotropic refractive index layer has a Δnd = 450 nm (wavelength 550 nm).

[0363] Furthermore, an anisotropic layer with an arbitrary refractive index of 45–315° was prepared by adjusting the chiral reagent in the same manner, according to another embodiment.

[0364]

[0365] ·Liquid crystal compound R1

[0366] [Chemical Formula 12]

[0367]

[0368] Polymer compound B2

[0369] [Chemical Formula 13]

[0370]

[0371] • Polymerization initiator P3

[0372] [Chemical Formula 14]

[0373]

[0374] Surfactant S3

[0375] [Chemical Formula 15]

[0376]

[0377] Chiral reagents

[0378] [Chemical Formula 16]

[0379]

[0380] <Fabrication of the Refractive Index Anisotropic Layer in Example 10>

[0381] Fabrication of anisotropic refractive index layers with a twisted structure exhibiting reverse wavelength dispersion

[0382] The liquid crystal layer forming composition 2 with the following composition was used, except that a refractive index anisotropic layer with a 90° twisted structure with reverse wavelength dispersion was formed in the same manner as the liquid crystal layer forming composition 1 described above.

[0383] The fabricated anisotropic refractive index layer has a refractive index Δnd = 350 nm (wavelength 550 nm).

[0384]

[0385]

[0386] ·Liquid crystal compound R2

[0387] [Chemical Formula 17]

[0388]

[0389] • Liquid crystal compound R3

[0390] [Chemical Formula 18]

[0391]

[0392] <Fabrication of the Refractive Index Anisotropic Layer in Example 3>

[0393] The alignment film PA1, which is the same alignment film used in the fabrication of the aforementioned light-absorbing anisotropic layer, was subjected to a rubbing treatment.

[0394] The liquid crystal layer forming composition 3, containing a disk-shaped liquid crystal compound with the following composition, was coated onto the alignment film prepared above using a winding bar. Next, to dry the solvent of the coating solution and to ripen the orientation of the (disc)-shaped liquid crystal compound, it was heated at 120°C for 90 seconds with warm air. Then, it was irradiated with UV light at 80°C to fix the orientation of the liquid crystal compound. Thus, an anisotropic refractive index layer with the disk-shaped liquid crystal twisted by 90° was formed. The Δnd of the formed anisotropic refractive index layer is 350 nm (wavelength 550 nm).

[0395]

[0396]

[0397] [Chemical Formula 19]

[0398] Disc-shaped liquid crystal compounds

[0399]

[0400] acrylate monomers:

[0401] Ethylene oxide modified trimethylolpropane triacrylate

[0402] (V#360, made by OSAKAORGANICCHEMICALINDUSTRYLTD.)

[0403] [Chemical Formula 20]

[0404] Pyridium salts

[0405]

[0406] Fluoropolymers (FP1)

[0407]

[0408] Fluoropolymers (FP3)

[0409]

[0410] <Fabrication of Switchable Optical Anisotropy Layer 1 in Example 4: TN Liquid Crystal Cell>

[0411] (Fabrication of TN mode liquid crystal cells)

[0412] A horizontally oriented polyimide alignment film was coated onto two glass substrates with ITO electrodes. After high-temperature drying to form the alignment film, a friction treatment was performed to form TN cells (in this embodiment, the alignment treatment was performed by twisting vertically by 90°). Then, a thermosetting sealant was spread on one of the two substrates, and bead mill spacers (5 μm in diameter) were spread on the other. After the two substrates were bonded together, they were vacuum-packed and heat-treated to form an empty liquid crystal cell. Liquid crystal (Merck MLC-9100) with positive dielectric anisotropy, refractive index anisotropy Δn = 0.0854 (589 nm, 20 °C), and Δε = +8.5 was injected into the cell using a vacuum liquid crystal injector, and a TN liquid crystal cell with Δnd = 430 nm was fabricated through sealing. Furthermore, since the inner surfaces of the upper and lower substrates are subjected to a friction treatment, the liquid crystal layer is twisted and aligned between the upper and lower substrates at a twist angle of 90° when no voltage is applied. By applying voltage, a TN cell with the liquid crystal aligned in the vertical direction is completed. Moreover, by adjusting the diameter of the aforementioned spacer, liquid crystal cells with arbitrary Δnd twisted structures can be formed.

[0413] <Example 5: Fabrication of a Switchable Optical Anisotropy Layer 2: VATN Liquid Crystal Cell>

[0414] (Anisotropic layer with electrically controllable refractive index)

[0415] A vertically oriented polyimide alignment film was coated onto two glass substrates with ITO electrodes. After high-temperature drying to form the alignment film, a friction treatment was performed to form VATN cells (in this embodiment, the alignment treatment was performed by twisting vertically by 90°). Then, a thermosetting sealant was spread on one of the two substrates, and bead mill spacers (5 μm in diameter) were spread on the other. After the two substrates were bonded together, they were vacuum-packed and heat-treated to form an empty liquid crystal cell. Liquid crystal (Merck MLC-6886) with negative dielectric anisotropy, refractive index anisotropy Δn = 0.0899 (589 nm, 20 °C), and Δε = approximately -3.6 was injected into the cell using a vacuum liquid crystal injector, and a VATN liquid crystal cell with Δnd = 450 nm was fabricated through sealing. Furthermore, since the inner surfaces of the upper and lower substrates are subjected to a friction treatment, the liquid crystal layer is vertically aligned between the upper and lower substrates when no voltage is applied, and is twisted and aligned at 90° by time and voltage. Moreover, by adjusting the diameter of the aforementioned spacer, liquid crystal cells with arbitrary Δnd twisted structures can be formed.

[0416] [Fabrication of Optical Laminates]

[0417] The light-absorbing anisotropic layers were appropriately bonded to both sides of the various anisotropic refractive index layers prepared above using commercially available adhesive SK2057 (manufactured by Soken Chemical & Engineering Co., Ltd.), and optical laminates of Examples 1 to 13 and Comparative Example 1 were prepared respectively. The thickness of SK2057 was approximately 20 μm.

[0418] [Fabrication of the View Control System in Examples 1-13]

[0419] The analysis of the LCD display device of the dynabook (manufactured by TOSHIBA CORPORATION), a laptop computer equipped with an LCD display device, shows that various optical laminates are bonded together between the BL (backlight) and the LCD panel using adhesive SK2057, thereby creating an image display device.

[0420] Furthermore, similarly, on the visual recognition side of the liquid crystal display device of the aforementioned dynabook (manufactured by TOSHIBA CORPORATION), various optical laminates can be bonded using adhesive SK2057, and the image display device of the present invention can also be realized in the same way.

[0421] (Evaluation of the tilt shading performance of the viewing angle control system)

[0422] The image display devices of Examples 1 to 13 all demonstrated omnidirectional light-blocking capability, and observation confirmed excellent field-of-view control. On the other hand, the viewing angle control system of Comparative Example 1 was light-blocked at every 90° azimuth angle, but not in other azimuths.

[0423] The brightness of the image display devices of the manufactured embodiments and comparative examples was measured. Based on the obtained data, the ratio of the front brightness to the maximum light leakage at the tilt (all directions, 60° polar angle) was defined as the front / tilt brightness ratio, and the light-shielding performance was evaluated. The results are shown in Table 1. The higher the value, the better the field of view control performance. In addition, regarding Embodiments 4 and 5, which are capable of electrically switching between a safety mode and a wide field of view mode, the light-shielding performance in the safety mode was evaluated.

[0424] When the field of view is less than 3, the control effect is poor: C

[0425] The field of view control effect is sufficient at 3-4 hours: B

[0426] The field of view control effect is good at 4-5: A

[0427] Excellent field of view control at 5° and above: AA

[0428] As shown in Table 1, compared with Comparative Example 1, the image display device of the present invention has good tilt-shielding performance.

[0429] (Moirén's evaluation)

[0430] The fabricated optical laminate was bonded to the liquid crystal display of the Apple Inc. iPhone 8 Plus smartphone, and the moiré pattern was evaluated.

[0431] Furthermore, the iPhone 8 Plus is a smartphone equipped with a high-definition liquid crystal display (LCD) device with a pixel density of 401 ppi. On this LCD device, a black and white stripe pattern alternating vertically for each pixel is displayed, and the moiré pattern is visually evaluated when viewed from the front. The optical laminates of Examples 1-13 and Comparative Example 1 do not have a periodic structure that interferes with the pixels of the image display device; therefore, the moiré pattern is not visually discernible, and they exhibit good display performance from the front. As described in Patent Document 3, the louvered film (commercially available) exhibits a texture known as moiré.

[0432]

[0433] As shown in Table 1, the optical laminate and image display device of the present invention have good tilting light-shielding performance, do not produce moiré patterns, and have good display performance on the front side.

[0434] Furthermore, the thickness of the optical laminates of the present invention (Examples 1-3, Examples 6-13) is all less than 150 μm, making them easy to bend. In contrast, the louvered film described in Patent Document 3 has a thickness of 500 μm, making it difficult to bend.

[0435] By disposing the optical laminate of the present invention on the window glass surface, it has been confirmed that privacy protection can be achieved. Furthermore, it has been found that by disposing the optical laminate of the present invention on the glass surface where sunlight enters, sunlight control can be achieved, and air conditioning power consumption in summer can be reduced. Moreover, it has been found that the same effect can be obtained when applied to vehicle windows.

[0436] Symbol Explanation

[0437] 1-Frontal visual recognition direction, 2-Oblique visual recognition direction, 11, 21-Absorption axis, 101a-Light absorption anisotropic layer, 101b-Polarizer layer, 102-Refractive index anisotropic layer (with twisted structure), 102c-Liquid crystal cell (with twisted structure), 200-Display device, 300-Liquid crystal cell, 30l-Liquid crystal layer, 302a-Polarizer (visual recognition side), 302b-Polarizer (light source side), 400-Surface light source, 500-Phase difference layer.

Claims

1. An optical laminate, comprising at least sequentially a first light-absorbing anisotropic layer, one or more refractive index anisotropic layers containing a liquid crystal compound with a twisted structure, and a second light-absorbing anisotropic layer. The first and second anisotropic light-absorbing layers contain anisotropic absorbing materials, compound E-1, and compound E-2, and the absorption axes are oriented at an angle of 60 to 90 degrees relative to the film surface. The anisotropic refractive index layer satisfies the following equation (3). Equation (3): 200nm≤Δn·d≤1500nm In equation (3), Δn·d is the product of the thickness d of the liquid crystal layer and the birefringence Δn of the liquid crystal, and Δn is set to the value at a wavelength of 550 nm. Compound E-1 Compound E-2 。 2. The optical laminate according to claim 1, wherein, In the first light-absorbing anisotropic layer and the second light-absorbing anisotropic layer, the absorption axis is oriented at an angle of 80 to 90 degrees relative to the film surface.

3. The optical laminate according to claim 1 or 2, wherein, The twist angle of the anisotropic refractive index layer with the twisted structure satisfies Equation I. 135·(2n-1)≥Twist Angle (degrees)≥45·(2n-1) Equation I In Equation I, n represents a natural number.

4. The optical laminate according to claim 1 or 2, wherein, The device comprises a first substrate and a second substrate respectively disposed on both sides of the anisotropic refractive index layer, with at least one side having a transparent electrode. The anisotropic refractive index layer is a liquid crystal cell. The anisotropic refractive index layer, the first substrate, and the second substrate constitute a liquid crystal panel capable of electrically switching birefringence.

5. The optical laminate according to claim 4, wherein, The liquid crystal unit is a TN liquid crystal unit capable of electrically switching birefringence or a VATN liquid crystal unit exhibiting a twisted structure under applied voltage.

6. The optical laminate according to claim 1 or 2, wherein, The anisotropic refractive index layer is formed by polymerizing a composition containing a disk-shaped or rod-shaped liquid crystal compound fixed in a twisted orientation along the film thickness direction.

7. The optical laminate according to claim 1 or 2, wherein, The anisotropic absorbing material is a dichroic substance.

8. The optical laminate according to claim 7, wherein, The dichroic substance is any one of dichroic pigments, carbon nanotubes, and anisotropic metal nanoparticles.

9. The optical laminate according to claim 7, wherein, In the first light-absorbing anisotropic layer and the second light-absorbing anisotropic layer, the liquid crystal compound and at least one dichroic substance are oriented perpendicularly to the film surface.

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

11. The optical laminate according to claim 1 or 2, wherein, The stacked liquid crystal compound and dichroic material are polarizers that are horizontally oriented relative to one or both of the first light-absorbing anisotropic layer and the second light-absorbing anisotropic layer.

12. The optical laminate according to claim 1 or 2, wherein, The first light-absorbing anisotropic layer and the second light-absorbing anisotropic layer have a blocking layer or a refractive index adjustment layer.

13. The optical laminate according to claim 1 or 2, wherein, The first light-absorbing anisotropic layer and the second light-absorbing anisotropic layer also contain a polymeric liquid crystal compound and a vertical alignment agent.

14. An image display device, wherein, The optical laminate of any one of claims 1 to 13 is disposed on the front surface.

15. An image display device, wherein, The optical laminate according to any one of claims 1 to 13 is disposed between the liquid crystal cell and the backlight source.

16. An image display device, comprising, in sequence: The optical laminate, phasor layer, and polarizer with absorption axis oriented horizontally relative to the film surface according to any one of claims 1 to 13.

17. The image display device according to any one of claims 14 to 16, wherein, The display section has a curved surface.

18. A glass composite comprising at least glass and an optical laminate according to any one of claims 1 to 13.

19. A glass composite comprising a laminated glass having an intermediate layer between two glass plates, said intermediate layer comprising an optical laminate according to any one of claims 1 to 13.

Images