Shaping method, optical film, cholesteric liquid crystal layer, optical laminate, and method for producing curved surface optical functional layer

Abstract

The present invention addresses the problem of providing a shaping method making it possible to obtain an optical film that can suppress ghost generation when used, for example, for a virtual reality display device, an optical film, a cholesteric liquid crystal layer, an optical laminate, and a method for producing a curve-shaped optical functional layer. The problem is solved by including a heating step of heating an optical film, a shaping step for pressing and deforming the optical film in a mold, and a cutting step for cutting the optical film. In the heating step, the optical film is heated by being irradiated with infrared light and the infrared light irradiation amount has an in-plane distribution in the optical film.

Description

Molding method, optical film, cholesteric liquid crystal layer, optical laminate, and method for producing curved optically functional layer

[0001] The present invention relates to a molding method, an optical film, a cholesteric liquid crystal layer, an optical laminate, and a method for producing a curved optically functional layer.

[0002] A virtual reality display device is a display device that allows a user to feel as if they are immersed in a virtual world by wearing a dedicated headset and viewing images displayed through a compound lens. Virtual reality display devices generally include an image display panel and a Fresnel lens, but the distance between the image display panel and the Fresnel lens is large, resulting in a thick headset and poor wearability. To address this issue, as described in Patent Documents 1 and 2, a compound lens configuration called a pancake lens (reciprocating optical system, folded optical system) has been proposed, which includes an image display panel, a reflective polarizer, and a half mirror, and reduces the overall thickness of the headset by guiding light emitted from the image display panel back and forth between the reflective polarizer and the half mirror.

[0003] Here, a reflective polarizer is a polarizer that has the function of reflecting one polarized light of incident light and transmitting the other polarized light. The reflected light and transmitted light by a reflective polarizer are polarized in mutually orthogonal directions. Here, the mutually orthogonal polarization states refer to polarization states located at antipodes on the Poincaré sphere, such as mutually orthogonal linearly polarized light, and right-handed circularly polarized light and left-handed circularly polarized light.

[0004] Known examples of reflective linear polarizers that produce linearly polarized transmitted and reflected light include stretched dielectric multilayer films and wire grid polarizers. Also, known examples of reflective circular polarizers that produce circularly polarized transmitted and reflected light include films having a light-reflecting layer (cholesteric liquid crystal layer) formed by fixing a cholesteric liquid crystal phase.

[0005] JP 2020-519964 A U.S. Patent No. 10,394,040

[0006] Patent Document 1 discloses a compound lens with a pancake lens configuration that uses a reflective linear polarizer as the reflective polarizer and includes, in this order, an image display panel, a reflective linear polarizer, and a half mirror. When including an image display panel, a reflective polarizer, and a half mirror in this order, the reflective polarizer needs to have the action of a concave mirror with respect to light rays incident from the half mirror side. In order to impart the action of a concave mirror to the reflective linear polarizer, a configuration in which the reflective linear polarizer is molded into a curved shape has been proposed. Furthermore, Patent Document 2 discloses a compound lens with a pancake lens configuration that uses a reflective linear polarizer as the reflective polarizer and includes, in this order, an image display panel, a half mirror, and a reflective linear polarizer. Patent Document 2 also proposes a configuration in which both the half mirror and the reflective polarizer are curved to improve field curvature. In this case, the reflective polarizer needs to have the action of a convex mirror.

[0007] As described above, a cholesteric liquid crystal layer, which is a reflective circular polarizer, can also be used as a reflective polarizer. As is well known, a cholesteric liquid crystal layer has a helical structure in which liquid crystal compounds are spirally rotated and stacked, and the helical pitch is defined as one helical pitch in which liquid crystal compounds are stacked one turn (360° rotation). The cholesteric liquid crystal layer selectively reflects predetermined circularly polarized light in a predetermined wavelength band and transmits other light. Therefore, such a cholesteric liquid crystal layer can be suitably used as a reflective circular polarizer in a pancake lens.

[0008] Cholesteric liquid crystal layers generally have no phase difference. That is, cholesteric liquid crystal layers generally have zero in-plane retardation. However, according to the inventors' studies, when a reflective polarizer using a cholesteric liquid crystal layer is molded into a curved shape as described in Patent Documents 1 and 2, the helical axis changes partially in the plane, resulting in a phase difference. A cholesteric liquid crystal layer with a phase difference cannot properly reflect and transmit incident light. Therefore, when such a cholesteric liquid crystal layer is used in a pancake lens constituting a virtual reality display device, unwanted light is transmitted, resulting in an increase in so-called ghosts (leakage light), in which unwanted images are observed.

[0009] The present invention has been made in consideration of the above-mentioned problems, and the problem that the present invention aims to solve is to provide a molding method for obtaining an optical film that can suppress the occurrence of ghosts when used, for example, in a virtual reality display device, and a method for producing an optical film, a cholesteric liquid crystal layer, an optical laminate, and a curved optically functional layer.

[0010] As a result of intensive research, the present inventors have found that when a cholesteric liquid crystal layer and a low retardation film (zero retardation film) are molded into an optical film having a curved shape, the generation of partial retardation due to molding can be suppressed by molding the film so as to selectively stretch the center.Furthermore, as a result of intensive research, the present inventors have found that the generation of partial retardation when molded into a curved shape can be canceled out by previously imparting an in-plane retardation to the cholesteric liquid crystal layer in a predetermined pattern.

[0011] That is, it has been found that the above-mentioned object can be achieved by the following configuration. [1] A molding method for an optical film, comprising: a heating step of heating an optical film; a molding step of pressing the optical film against a mold and deforming it to conform to the shape of the mold; and a cutting step of cutting the optical film, wherein the heating step is a step of heating the optical film by irradiating it with infrared rays, and the amount of infrared irradiation has a distribution within the plane of the optical film. [2] The molding method according to [1], wherein the mold is a non-developable concave surface with a positive Gaussian curvature, and when a position within the plane of the optical film is projected onto the mold from the normal direction of the main surface of the optical film, the amount of infrared irradiation to the optical film at the vertex of the concave surface is greater than the amount of infrared irradiation to the optical film at the end of the concave surface. [3] A molding method for an optical film, comprising: a heating step of heating an optical film; a molding step of pressing the optical film against a mold and deforming it to conform to the shape of the mold; and a cutting step of cutting the optical film, wherein the surface of the mold in contact with the optical film is a non-developable concave surface with a positive Gaussian curvature and has an elliptical outer circumferential shape; the cut shape in the cutting step is elliptical, and the major axis of the elliptical outer circumferential shape of the optical film cut out by cutting is greater than 50% and smaller than 95% of the major axis of the elliptical outer circumferential shape of the mold. [4] A method for molding an optical film, comprising: a heating step of heating an optical film; a molding step of pressing the optical film against a mold and deforming the optical film to conform to the shape of the mold; and a cutting step of cutting the optical film, wherein in the heating step, a region of the optical film that contacts the mold is heated to a temperature higher than the glass transition temperature Tg of the optical film; and in the molding step, pressing of the optical film against the mold is controlled so that the temperature of the region of the optical film that contacts the mold becomes lower than the glass transition temperature Tg immediately after the optical film contacts the mold.[5] A method for molding an optical film, comprising: a heating step of heating a mold; a molding step of pressing the heated mold against an optical film to deform it according to the shape of the mold; and a cutting step of cutting the optical film, wherein the mold has a non-developable convex surface with a positive Gaussian curvature, and the apex of the convex surface of the mold is pressed against the center of the optical film in the molding step. [6] The molding method according to [5], wherein the cut shape of the optical film in the cutting step is elliptical, and the molding step involves pressing the optical film against the mold while restraining its position on the line of the ellipse that will become the cut shape. [7] A cholesteric liquid crystal layer, wherein the cholesteric liquid crystal layer has a retardation region in which the retardation increases from the center to the outside, and in the retardation region, the direction of the slow axis at a point in the retardation region is perpendicular to the direction from the center toward the point. [8] An optical laminate having a plurality of cholesteric liquid crystal layers according to [7]. [9] The optical laminate according to [8], which is formed by alternately laminating cholesteric liquid crystal layers formed using a rod-shaped liquid crystal compound and cholesteric liquid crystal layers formed using a discotic liquid crystal compound.

[10] A method for producing a curved optically functional layer, comprising: a cholesteric liquid crystal layer production step of producing the cholesteric liquid crystal layer according to [7]; and a molding step of curvedly molding the cholesteric liquid crystal layer so as to eliminate the retardation of the cholesteric liquid crystal layer.

[11] The method for producing a curved optically functional layer according to

[10] , wherein in the molding step, the cholesteric liquid crystal layer is placed on a mold having a concave molding surface so that the bottom of the concave molding surface of the mold coincides with the center of the cholesteric liquid crystal layer, and the cholesteric liquid crystal layer is deformed to fit the concave molding surface.

[12] An optical film having a non-developable surface with a positive Gaussian curvature, the optical film being a cholesteric liquid crystal layer, wherein, when an evaluation wavelength for in-plane retardation is a wavelength obtained by subtracting 20 nm from a half-maximum wavelength on the side shorter than the selective reflection center wavelength of the cholesteric liquid crystal layer, the in-plane retardation A at the evaluation wavelength at the center of the cholesteric liquid crystal layer is less than 2% of the evaluation wavelength, and the in-plane retardation B at the evaluation wavelength at the outer edge of the cholesteric liquid crystal layer is less than 2% of the evaluation wavelength.

[13] An optical film having a non-developable surface with a positive Gaussian curvature, wherein the optical film does not have selective reflection properties, and the in-plane retardation A at the center of the optical film at a wavelength of 550 nm is less than 11 nm, and the in-plane retardation B at the outer edge of the optical film at a wavelength of 550 nm is less than 11 nm.

[14] The optical film according to

[12] or

[13] , wherein the peripheral shape is elliptical.

[0012] According to the present invention, it is possible to provide a molding method for obtaining an optical film that can suppress the occurrence of ghosts when used in, for example, a virtual reality display device, an optical film, a cholesteric liquid crystal layer, an optical laminate, and a method for producing a curved optically functional layer.

[0013] 1 is an example of a virtual reality display device in which the optical film of the first embodiment of the present invention can be used, showing an example of light rays of a main image. FIG. 2 is an example of a virtual reality display device in which the optical film of the first embodiment of the present invention can be used, showing an example of light rays of a ghost. FIG. 3 is a schematic diagram showing an example of a laminated optical body including the optical film of the first embodiment of the present invention. FIG. 4 is a schematic diagram showing an example of an optical film of the first embodiment of the present invention. FIG. 5 is a schematic diagram of an exposure mask. FIG. 6 is a schematic diagram for explaining the effects of the first embodiment of the present invention. FIG. 7 is a conceptual diagram showing an example of a cholesteric liquid crystal layer. FIG. 8 is a conceptual diagram showing an example of a view of a part of a liquid crystal compound in a cholesteric liquid crystal layer of a second embodiment of the present invention, viewed from the direction of the helical axis. FIG. 9 is a diagram showing a part of a plurality of liquid crystal compounds twistedly aligned along the helical axis, viewed from the direction of the helical axis, in the cholesteric liquid crystal layer of the second embodiment of the present invention. FIG. 10 is a diagram conceptually showing the existence probability of a liquid crystal compound, viewed from the direction of the helical axis, in the cholesteric liquid crystal layer of the second embodiment of the present invention. FIG. 11 is a schematic diagram of an exposure mask used when producing the cholesteric liquid crystal layer of the second embodiment of the present invention. FIG. 12 is a conceptual diagram showing the slow axis for each region of the cholesteric liquid crystal layer of the second embodiment of the present invention.

[0014] The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In addition, in this specification, parallel and perpendicular do not mean parallel and perpendicular in the strict sense, but mean a range of ±5° from parallel or perpendicular.

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

[0016] The present invention will be described in detail below with reference to the drawings. The following description of the constituent elements may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0017] In this specification, "orthogonal" does not mean strictly 90°, but means 90°±10°, preferably 90°±5°. Furthermore, "parallel" does not mean strictly 0°, but means 0°±10°, preferably 0°±5°. Furthermore, "45°" does not mean strictly 45°, but means 45°±10°, preferably 45°±5°. However, in expressions related to polarization, "mutually orthogonal polarization states" refer to polarization states located at antipodes on the Poincaré sphere, and as described above, for example, this includes mutually orthogonal linearly polarized light, and right-handed circularly polarized light (right circularly polarized light) and left-handed circularly polarized light (left circularly polarized light), etc.

[0018] In this specification, "absorption axis" refers to the polarization direction in which absorbance is maximized in a plane when linearly polarized light is incident. "Reflection axis" refers to the polarization direction in which reflectance is maximized in a plane when linearly polarized light is incident. "Transmission axis" refers to the direction perpendicular to the absorption axis or reflection axis in a plane. "Slow axis" refers to the direction in which refractive index is maximized in a plane.

[0019] In this specification, unless otherwise specified, phase difference refers to in-plane retardation and is referred to as Re(λ). Here, Re(λ) represents the in-plane retardation at wavelength λ, and unless otherwise specified, wavelength λ is 550 nm. Furthermore, in this specification, retardation in the thickness direction at wavelength λ is referred to as Rth(λ). Re(λ) and Rth(λ) can be values ​​measured at wavelength λ using an AxoScan OPMF-1 (manufactured by OptoScience). By inputting the average refractive index ((nx + ny + nz) / 3) and film thickness (d (μm)) into AxoScan, the following slow axis direction (°) can be calculated: Re(λ) = R0(λ) Rth(λ) = ((nx + ny) / 2 - nz) × d.

[0020] In this specification, the liquid crystal composition and liquid crystal compound conceptually include those that no longer exhibit liquid crystallinity due to curing or the like.

[0021] [First Embodiment] <Optical Film> The optical film of the first embodiment of the present invention has a curved surface shape. Specifically, the optical film of the first embodiment of the present invention has a curved surface shape of a non-developable surface with a positive Gaussian curvature. Examples of such curved surface shapes include a spherical surface, a parabolic surface, an ellipsoidal surface, an aspherical surface whose curvature changes from the center outward, and a curved surface asymmetric with respect to the center, such as a curved surface asymmetric with respect to the optical axis in the diameter direction in the case of a circular lens. Furthermore, in the optical film of the first embodiment of the present invention having such a curved surface shape, there is no limitation on the peripheral shape (shape of the peripheral edge), i.e., the planar shape. Various shapes such as an ellipse, an oval other than an ellipse, a polygon, and an irregular shape are available. Among these, an ellipse is preferred. In the present invention, the term "ellipse" also includes a circle. The planar shape refers to the shape when viewed from the normal direction of the top (bottom) of the curved surface of the optical film. For example, when the optical film having a curved surface shape is a lens, it usually refers to the shape when viewed from the optical axis direction.

[0022] The optical film of the first embodiment of the present invention is composed of a cholesteric liquid crystal layer or a film with a small phase difference, a so-called zero retardation film. Specifically, a first aspect of the optical film of the first embodiment of the present invention is composed of a cholesteric liquid crystal layer having the curved shape described above, and, when the evaluation wavelength (measurement wavelength) is a wavelength obtained by subtracting 20 nm from the half-value wavelength on the side shorter than the selective reflection center wavelength of the cholesteric liquid crystal layer, the in-plane retardation A at the evaluation wavelength at the center is less than 2% of the evaluation wavelength, and the in-plane retardation B at the evaluation wavelength at the outer edge is less than 2% of the evaluation wavelength. For example, when the half-value wavelength on the side shorter than the selective reflection center wavelength of the cholesteric liquid crystal layer is 430 nm, the first aspect of the optical film of the first embodiment of the present invention is an optical film in which, when light of a wavelength of 410 nm is used as the evaluation wavelength for in-plane retardation, the in-plane retardation A at the center is less than 8.2 nm and the in-plane retardation B at the outer edge is also less than 8.2 nm. In addition, when the optical film of the first aspect of the first embodiment of the present invention has a plurality of cholesteric liquid crystal layers, the wavelength obtained by subtracting 20 nm from the half-value wavelength on the side shorter than the selective reflection central wavelength of the cholesteric liquid crystal layer having the shortest selective reflection central wavelength may be used as the evaluation wavelength for the in-plane retardation of the optical film.

[0023] Furthermore, a second aspect of the optical film of the first embodiment of the present invention is a film having a curved surface shape as described above and no selective reflectivity, in which the in-plane retardation A at the center at a wavelength of 550 nm is less than 11 nm, and the in-plane retardation B at the outer edge at the evaluation wavelength is less than 11 nm.

[0024] In the optical film of the first embodiment of the present invention, the center usually refers to the lowest part (deepest part) when the curved surface is concave, and the highest part when the curved surface is convex. When the optical film functions as a lens, the center usually corresponds to the optical axis. Furthermore, the outer edge (edge) refers to a point 5 mm inward from the outermost edge of the lens.

[0025] That is, the optical film of the first embodiment of the present invention is composed of a curved cholesteric liquid crystal layer or a curved film without selective reflectivity, and has a small phase difference, i.e., in-plane retardation, over the entire surface. The optical film of the first embodiment of the present invention can suppress the occurrence of ghosts when used, for example, as a reflective polarizer for a pancake lens constituting a virtual reality display device.

[0026] The optical film of the first embodiment of the present invention may be used as a laminated optical body in combination with various optical elements such as a support (transparent film), a retardation film (retardation plate), a polarizer (polarizing plate), a reflective polarizer, and an antireflection film. The laminated optical body will be described in detail later.

[0027] [Film without Selective Reflectivity] In the optical film of the first embodiment of the present invention, the film without selective reflectivity can be a variety of films with small phase difference made of a low-birefringence polymer resin, so-called zero-retardation films (low-retardation films). Examples of low-birefringence polymer resins include low-birefringence organic materials used in optical disk substrates, pickup lenses, camera, microscope, and video camera lenses, liquid crystal display substrates, prisms, optical interconnection components, optical fibers, light guide plates for liquid crystal displays, lenses for laser beam printers, projectors, and facsimiles, Fresnel lenses, contact lenses, polarizing filter protective films, and microlens arrays, where birefringence can cause image formation problems or signal noise. Examples of such films include acrylic resins (e.g., acrylic acid esters such as polymethyl (meth)acrylate), polycarbonate, cyclic polyolefins such as cyclopentadiene-based polyolefins and norbornene-based polyolefins, polyolefins such as polypropylene, aromatic vinyl polymers such as polystyrene, polyarylates, and cellulose acylates. There is no limitation on the thickness of these films, and an appropriate thickness may be set as appropriate depending on the forming material, application, and the like.

[0028] [Cholesteric Liquid Crystal Layer] As described above, the cholesteric liquid crystal layer is formed by fixing a cholesteric liquid crystal phase and has a helical structure in which liquid crystal compounds are stacked in a spiral. One helical pitch is defined as a configuration in which liquid crystal compounds 40 are stacked in a spiral with one rotation (360° rotation), and the helically spiraling liquid crystal compounds are stacked in multiple pitches. As is well known, the cholesteric liquid crystal layer has selective reflectivity. Specifically, the cholesteric liquid crystal layer selectively reflects light in a predetermined wavelength band and transmits light in other wavelength bands. The cholesteric liquid crystal layer selectively reflects right-handed circularly polarized light and transmits left-handed circularly polarized light, or selectively reflects left-handed circularly polarized light and transmits right-handed circularly polarized light. That is, the cholesteric liquid crystal layer selectively reflects right-handed or left-handed circularly polarized light in a predetermined wavelength band and transmits the rest. In other words, the cholesteric liquid crystal layer separates incident light into right-handed and left-handed circularly polarized light in a specific wavelength band, specularly reflecting one circularly polarized light and transmitting the other. In a cholesteric liquid crystal phase, the central wavelength of selective reflection (selective reflection central wavelength λ) depends on the length of one helical pitch (helical pitch P) in the cholesteric liquid crystal phase and follows the relationship λ = n × P with the average refractive index n of the cholesteric liquid crystal phase. Therefore, by adjusting this helical pitch, the selective reflection central wavelength, i.e., the selective reflection wavelength range, can be adjusted. The longer the helical pitch P, the longer the selective reflection central wavelength of the cholesteric liquid crystal phase. Furthermore, the half-width Δλ (nm) of the wavelength range exhibiting selective reflection (circularly polarized light reflection wavelength range) depends on the Δn and helical pitch P of the cholesteric liquid crystal phase and follows the relationship Δλ = Δn × P. Therefore, the width of the selective reflection wavelength range can be controlled by adjusting Δn. Δn can be adjusted by the type and mixing ratio of the liquid crystal compounds forming the cholesteric liquid crystal layer, and the temperature at which the alignment is fixed.

[0029] In the present invention, various known cholesteric liquid crystal layers can be used. As the cholesteric liquid crystal layer, for example, a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase can be used, with reference to JP 2020-060627 A and the like. A cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase is preferred because it has a high degree of polarization of transmitted light despite being a thin film. A cholesteric liquid crystal layer is preferred as an optical film used for curved surface molding, from the viewpoint that a decrease in polarization degree and distortion of the polarization axis are suppressed when the layer is stretched or molded into a three-dimensional shape, etc. Furthermore, a decrease in polarization degree due to distortion of the polarization axis is unlikely to occur.

[0030] The optical film of the first embodiment of the present invention may be a laminate of multiple cholesteric liquid crystal layers. As an example, a laminate of four cholesteric liquid crystal layers is preferred, including at least a blue light-reflecting layer having a reflectance of 40% or more at a wavelength of 460 nm, a green light-reflecting layer having a reflectance of 40% or more at a wavelength of 550 nm, a yellow light-reflecting layer having a reflectance of 40% or more at a wavelength of 600 nm, and a red light-reflecting layer having a reflectance of 40% or more at a wavelength of 650 nm. This configuration is preferred because it can exhibit high reflection characteristics over a wide wavelength range in the visible range. The reflectances mentioned above are those when unpolarized light is incident on the cholesteric liquid crystal layer at each wavelength. Furthermore, the blue light-reflecting layer, green light-reflecting layer, yellow light-reflecting layer, and red light-reflecting layer, which are cholesteric liquid crystal layers formed by fixing a cholesteric liquid crystal phase, may have a pitch gradient structure in which the helical pitch of the cholesteric liquid crystal phase changes continuously in the thickness direction. According to the pitch gradient structure, for example, referring to JP 2020-060627 A, a green light reflective layer and a yellow light reflective layer can be continuously manufactured.

[0031] In the optical film of the first embodiment of the present invention, the cholesteric liquid crystal layer preferably comprises a blue light-reflecting layer, a green light-reflecting layer, a yellow light-reflecting layer, and a red light-reflecting layer laminated in this order. The cholesteric liquid crystal layer is often combined with a retardation layer. In this case, the blue light-reflecting layer is preferably disposed on the side opposite the retardation layer that converts circularly polarized light into linearly polarized light, i.e., on the light source side. With this arrangement, light passes through the blue light-reflecting layer, the green light-reflecting layer, the yellow light-reflecting layer, and the red light-reflecting layer in this order. The inventors believe that the suppression of ghost generation by disposing the blue light-reflecting layer on the light source side is due to the suppression of the influence of Rth. The estimated mechanism is described below. In a cholesteric liquid crystal layer used as a light-reflecting layer, the film thickness required to obtain sufficient reflectance (e.g., 40% or more) increases with wavelength. Therefore, if a light-reflecting layer that reflects long-wavelength light is present on the light source side, its film thickness increases, resulting in a higher Rth for light passing through that layer. For these reasons, it is considered preferable that the reflection band of the light-reflecting layer disposed on the light source side be on the short wave side.

[0032] The optical film of the first embodiment of the present invention preferably includes a cholesteric liquid crystal layer containing a rod-shaped liquid crystal compound and a cholesteric liquid crystal layer containing a discotic liquid crystal compound. This configuration is preferable because the cholesteric liquid crystal phase containing a rod-shaped liquid crystal compound has a positive Rth, while the cholesteric liquid crystal phase containing a discotic liquid crystal compound has a negative Rth. Therefore, the Rths of the two phases are offset, thereby suppressing the occurrence of ghost images even with light incident from an oblique direction. According to the inventors' studies, in this case, the optical film preferably includes a blue-light-reflecting layer made of a cholesteric liquid crystal layer containing a discotic liquid crystal compound, a green-light-reflecting layer made of a cholesteric liquid crystal layer containing a rod-shaped liquid crystal compound, a yellow-light-reflecting layer made of a cholesteric liquid crystal layer containing a discotic liquid crystal compound, and a red-light-reflecting layer made of a cholesteric liquid crystal layer containing a rod-shaped liquid crystal compound, in this order. The order of the reflective layers and the types of liquid crystals are merely examples, and are not limited to these configurations.

[0033] The manner in which Rth is cancelled out can be expressed by the following formula. In an optical laminate film having n light-reflecting layers, when the light-reflecting layers are named L1, L2, L3, ..., Ln in order from the light source side, the sum of the Rth of each layer from light-reflecting layer L1 to light-reflecting layer Li is SRthi. Specifically, it is expressed by the following formula: SRth1=Rth1 SRth2=Rth1+Rth2 ... SRthi=Rth1+Rth2 ... +Rthi ... SRthn=Rth1+Rth2 ... +Rthi ... +Rthn The absolute values ​​of all these SRthi (SRth1 to SRthn) are preferably 0.3 μm or less, more preferably 0.2 μm or less, and most preferably 0.1 μm or less. The Rth of each layer in the above formula is determined by the formula for calculating Rth described in

[0023] .

[0034] The thickness of the cholesteric liquid crystal layer is not particularly limited, but from the viewpoint of thinning, it is preferably 30 μm or less, and more preferably 15 μm or less.

[0035] Furthermore, when a cholesteric liquid crystal layer is stretched or molded, the reflection wavelength range of the cholesteric liquid crystal layer may shift, so it is preferable that the reflection wavelength range be selected in advance, taking into account this wavelength shift. For example, when a cholesteric liquid crystal layer is used, the film may be stretched by stretching or molding, which may reduce the helical pitch of the cholesteric liquid crystal layer. Therefore, it is preferable to set the helical pitch of the cholesteric liquid crystal phase to a large value in advance. Furthermore, in consideration of a short-wave shift in the reflection wavelength range due to stretching or molding, it is also preferable that the cholesteric liquid crystal layer has an infrared light reflective layer with a reflectance of 40% or more at a wavelength of 800 nm. Furthermore, when the stretching ratio during stretching or molding is not uniform within the plane, an appropriate reflection wavelength range may be selected at each location within the plane in accordance with the wavelength shift due to stretching. In other words, there may be regions within the plane where the reflection wavelength range differs. Furthermore, in consideration of the fact that the stretching ratio will differ at each location within the plane, it is also preferable to set the reflection wavelength range in advance to be wider than the required wavelength range.

[0036] (Method for Producing a Cholesteric Liquid Crystal Layer) A cholesteric liquid crystal layer can be formed by applying a liquid crystal composition, which is prepared by dissolving a liquid crystal compound, a chiral agent, a polymerization initiator, and optionally a surfactant, in a solvent onto a support or onto an underlayer (alignment film) formed on the support, drying the composition to obtain a coating film, orienting the liquid crystal compound in the coating film, and irradiating the coating film with actinic rays to harden the liquid crystal composition. This allows the formation of a cholesteric liquid crystal layer having a cholesteric liquid crystal structure in which cholesteric regularity (cholesteric liquid crystal phase) is fixed.

[0037] [Coating Method] Examples of the coating method include known methods such as roll coating, gravure printing, spin coating, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, die coating, spraying, and inkjet printing.

[0038] [Method for imparting an in-plane distribution to the helical pitch] The cholesteric liquid crystal layer constituting the optical film of the first embodiment of the present invention may have an in-plane distribution to the helical pitch. When the cholesteric liquid crystal layer has an in-plane distribution to the helical pitch, it is possible to suppress variations in the selective reflection wavelength range in the plane even when the film thickness changes due to molding into a curved shape, as described below. One method for imparting an in-plane distribution to the helical pitch of the cholesteric liquid crystal layer is to use, for example, a chiral agent whose HTP changes upon photoisomerization.

[0039] Details will be explained. A liquid crystal composition containing a chiral agent whose HTP changes upon photoisomerization is applied to a cholesteric liquid crystal layer, which is then heat-treated as needed to align it. Irradiating the layer with light corresponding to the photoisomerization changes the HTP of the chiral agent, thereby changing the helical pitch of the cholesteric liquid crystal layer and thereby changing the reflection wavelength. Taking advantage of this property, the aligned cholesteric liquid crystal layer is irradiated with light in a pattern using an exposure mask or the like to photoisomerize it, resulting in a pattern in which the reflection wavelength is changed only in the irradiated region. After obtaining the pattern, the entire cholesteric liquid crystal layer is exposed to light to harden the liquid crystal composition, polymerizing the liquid crystal composition, ultimately resulting in a cholesteric liquid crystal layer with an in-plane distribution of helical pitch (patterned cholesteric liquid crystal layer). After hardening, the patterned cholesteric liquid crystal layer no longer undergoes photoisomerization and has stable properties.

[0040] To effectively form this pattern, it is preferable to separate the light irradiation for photoisomerization from the light irradiation for curing. In other words, to effectively form this pattern, it is preferable that when one of photoisomerization and curing is progressing, the other is not progressing as much as possible. Examples of methods for separating the two include separating them based on oxygen concentration and on exposure wavelength.

[0041] First, regarding oxygen concentration, photoisomerization is not easily affected by oxygen concentration, but curing is generally more difficult to occur at higher oxygen concentrations, although this depends on the initiator used. Therefore, photoisomerization is carried out under conditions of high oxygen concentration, for example, in the atmosphere, and curing is carried out under conditions of low oxygen concentration, for example, using a nitrogen atmosphere with an oxygen concentration of 300 volume ppm or less. This makes it easier to distinguish between photoisomerization and curing.

[0042] Regarding the exposure wavelength, photoisomerization of the chiral agent is facilitated at the absorption wavelength of the chiral agent, and curing is facilitated at the absorption wavelength of the photopolymerization initiator. Therefore, by selecting the chiral agent and the photopolymerization initiator so that their absorption wavelengths differ, it becomes possible to distinguish between photoisomerization and curing depending on the exposure wavelength.

[0043] If necessary, one or both of the photoisomerization and curing may be carried out under heating. The heating temperature is preferably 25 to 140°C, more preferably 30 to 100°C.

[0044] As an alternative to the method using a chiral agent whose HTP changes upon photoisomerization, there is also a method in which the liquid crystal composition is first cured in a pattern and then isomerized in the uncured regions. That is, the aligned cholesteric liquid crystal phase is first irradiated with light for curing in a pattern using an exposure mask or the like. Then, the entire surface is irradiated with light for photoisomerization. The previously cured regions can no longer undergo pitch changes due to photoisomerization. Therefore, only the previously uncured regions undergo pitch changes due to photoisomerization, resulting in a change in the reflection wavelength. In this case, after obtaining the pattern, the entire cholesteric liquid crystal layer is exposed to light for curing the liquid crystal composition, and the liquid crystal composition is polymerized, thereby obtaining the final patterned cholesteric liquid crystal layer.

[0045] [Direct Coating of Each Layer] As described above, the optical film of the first embodiment of the present invention may be a laminate of multiple cholesteric liquid crystal layers. In this case, it is preferable that adjacent layers are formed directly between each cholesteric liquid crystal layer without an adhesive layer. When forming a layer, the adhesive layer can be eliminated by coating directly on an adjacent layer that has already been formed. In the following description, the cholesteric liquid crystal layer is also referred to as a "light-reflecting layer." Furthermore, to reduce the refractive index difference in all in-plane directions, it is preferable to arrange the liquid crystal compound so that the alignment direction (slow axis direction) continuously changes at the interface. For example, when forming a light-reflecting layer containing rod-shaped liquid crystals on a light-reflecting layer containing discotic liquid crystals, a coating liquid containing rod-shaped liquid crystals can be directly coated, and the alignment force of the discotic liquid crystals in the light-reflecting layer containing discotic liquid crystals can be used to align the slow axis direction continuously at the interface.

[0046] [Method of Adhering Each Layer] As described above, the optical film of the first embodiment of the present invention may be a laminate of multiple cholesteric liquid crystal layers (light-reflecting layers). In this case, each light-reflecting layer can be attached by any attachment method. Attachment can be performed using a pressure-sensitive adhesive or adhesive. Any commercially available pressure-sensitive adhesive can be used. From the viewpoint of thinning the optical film and reducing the surface roughness Ra, the thickness of the pressure-sensitive adhesive is preferably 25 μm or less, more preferably 15 μm or less, and even more preferably 6 μm or less. Furthermore, it is preferable that the pressure-sensitive adhesive is one that is less likely to outgas. In particular, when stretching or molding is performed, a vacuum process or a heating process may be performed, and it is preferable that the pressure-sensitive adhesive does not outgas even under these conditions. Any commercially available adhesive can be used as the adhesive. Specific examples of adhesives that can be used include epoxy resin-based adhesives and acrylic resin-based adhesives. From the viewpoint of thinning the optical film and reducing the surface roughness Ra, the thickness of the adhesive is preferably 25 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less. Furthermore, from the viewpoint of thinning the adhesive layer and applying the adhesive to the adherend with a uniform thickness, the viscosity of the adhesive is preferably 300 cP or less, more preferably 100 cP or less. Furthermore, if the adherend has a surface irregularity, the pressure-sensitive adhesive and adhesive can be selected to have an appropriate viscoelasticity or thickness so as to embed the surface irregularities of the layer to be adhered, thereby reducing the surface roughness Ra of the cholesteric liquid crystal layer. From the viewpoint of embedding the surface irregularities, the pressure-sensitive adhesive and adhesive preferably have a viscosity of 50 cP or more. Furthermore, the thickness is preferably greater than the height of the surface irregularities. Examples of methods for adjusting the viscosity of the adhesive include using a solvent-containing adhesive. In this case, the viscosity of the adhesive can be adjusted by adjusting the ratio of the solvent. Furthermore, the thickness of the adhesive can be further reduced by applying the adhesive to the adherend and then drying the solvent.

[0047] In order to reduce unnecessary reflection and suppress a decrease in the degree of polarization of transmitted light in a cholesteric liquid crystal layer, it is preferable that the adhesive and pressure-sensitive adhesive used to bond each layer have a small refractive index difference with adjacent layers. Because the liquid crystal layer has birefringence, the refractive index in the fast axis direction differs from that in the slow axis direction. When the average refractive index n ave of the liquid crystal layer is calculated by adding the refractive indices in the fast axis direction and the slow axis direction and dividing the sum by 2, the difference in refractive index n ave between the adjacent adhesive or bonding layer and the adjacent layer is preferably 0.075 or less, more preferably 0.05 or less, and even more preferably 0.025 or less. The refractive index of the adhesive and pressure-sensitive adhesive can be adjusted by mixing, for example, titanium oxide fine particles or zirconia fine particles. Furthermore, while the cholesteric liquid crystal layer has in-plane refractive index anisotropy, it is preferable that the refractive index difference with adjacent layers is 0.10 or less in all directions in the plane. Therefore, the adhesive and pressure-sensitive adhesive may have in-plane refractive index anisotropy. This also applies to laminated optical bodies using the optical film (cholesteric liquid crystal layer) of the first embodiment of the present invention, even when the laminated optical body includes a retardation layer and a linear polarizer having in-plane refractive index anisotropy. Furthermore, when the optical film of the first embodiment of the present invention is composed of multiple cholesteric layers, a refractive index adjustment layer having a smaller difference in refractive index between the fast axis direction and the slow axis direction than the cholesteric liquid crystal layer may be provided between the cholesteric liquid crystal layer and the adhesive, or between the cholesteric liquid crystal layer and the adhesive. In this case, the refractive index adjustment layer preferably contains cholesteric liquid crystal. By providing a refractive index adjustment layer, interfacial reflection can be further suppressed, and the occurrence of ghosts can be further suppressed. Furthermore, the average refractive index of the refractive index adjustment layer is preferably smaller than the average refractive index of the cholesteric liquid crystal layer. Furthermore, the central wavelength of the reflected light of the refractive index adjustment layer may be smaller than 430 nm or larger than 670 nm, and is more preferably smaller than 430 nm.

[0048] Furthermore, the adhesive layer between each cholesteric liquid crystal layer preferably has a thickness of 100 nm or less. When the adhesive layer is 100 nm or less, the refractive index difference is less noticeable for light in the visible range, suppressing unnecessary reflection. The adhesive layer thickness is more preferably 50 nm or less, and even more preferably 30 nm or less. An example of a method for forming an adhesive layer having a thickness of 100 nm or less is a method of depositing a ceramic adhesive such as silicon oxide (SiOx layer) on the bonding surface. The bonding surface of the bonding member may be subjected to a surface modification treatment such as plasma treatment, corona treatment, or saponification treatment before bonding. A primer layer may also be provided on the bonding surface of the bonding member. Furthermore, when there are multiple bonding surfaces, the type and thickness of the adhesive layer may be adjusted for each bonding surface. Specifically, an adhesive layer having a thickness of 100 nm or less can be provided by, for example, the following steps (1) to (3): (1) The layers to be laminated are bonded to a temporary support made of a glass substrate. (2) A SiOx layer having a thickness of 100 nm or less is formed on both the surface of the layer to be laminated and the surface of the layer to be laminated by vapor deposition or the like. Vapor deposition can be performed using, for example, a vapor deposition device manufactured by ULVAC (model number ULEYES) using SiOx powder as the vapor deposition source. It is also preferable to subject the surface of the formed SiOx layer to plasma treatment. (3) After the formed SiOx layers are bonded together, the temporary support is peeled off. The bonding is preferably performed at a temperature of, for example, 120°C.

[0049] The coating, adhesion, and lamination of each layer may be performed by roll-to-roll or sheet-to-sheet. The roll-to-roll method is preferred because it can improve productivity and reduce axial misalignment of each layer. On the other hand, the sheet-to-sheet method is preferred because it is suitable for small-lot, high-mix production and because it allows the selection of a special adhesion method such as the above-mentioned adhesive layer thickness of 100 nm or less. Examples of methods for applying the adhesive to the adherend include known methods such as roll coating, gravure printing, spin coating, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, die coating, spraying, and inkjet printing.

[0050] As described above, the cholesteric liquid crystal layer of the optical film of the first embodiment of the present invention can be laminated with other layers to form a laminated optical body. These layers may include a support, an alignment layer, and the like. Here, the support and alignment layer may be a temporary support that is peeled off and removed when preparing the laminated optical body. Using a temporary support is preferable because the laminated optical body can be thinned by transferring the cholesteric liquid crystal layer to another laminate and then peeling off and removing the temporary support. Furthermore, the adverse effect of the retardation of the temporary support on the polarization degree of transmitted light can be eliminated. The type of support is not particularly limited, but a transparent support is preferred. For example, films of cellulose acylate, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate, cyclic polyolefin, polyolefin, polyamide, polystyrene, polyester, and the like can be used. Among these, films of cellulose acylate, cyclic polyolefin, polyacrylate, polymethacrylate, and the like are preferred. Furthermore, commercially available products may be used for these films. Examples of commercially available products include cellulose acetate films such as "TD80U" and "Z-TAC" manufactured by Fujifilm Corporation. When the support is a temporary support, a support with high tear strength is preferred in order to prevent breakage during peeling. In this regard, polycarbonate and polyester films are preferred. Furthermore, the support preferably has a small phase difference in order to suppress adverse effects on the polarization degree of transmitted light. Specifically, the support preferably has an Re (in-plane retardation) of 10 nm or less, and an absolute value of Rth (thickness retardation) of 50 nm or less. Even if the support is used as the temporary support described above, it is preferable that the temporary support have a small phase difference in order to perform quality inspections of the cholesteric liquid crystal layer and other laminates during the manufacturing process of the laminated optical body.

[0051] Furthermore, various sensors using near-infrared light as a light source for eye tracking, facial expression recognition, iris authentication, etc. may be incorporated into optical systems such as virtual reality display devices and electronic viewfinders. In this case, in order to minimize the influence on the sensors, it is preferable that the cholesteric liquid crystal layer is transparent to near-infrared light.

[0052] [Laminated Optical Body] As described above, the optical film (cholesteric liquid crystal layer) of the first embodiment of the present invention may be laminated with other film-like optical elements to be used as a laminated optical body. Here, a preferred example of the laminated optical body has, in addition to the cholesteric liquid crystal layer, a retardation layer that converts circularly polarized light into linearly polarized light, and a linear polarizer, in this order.

[0053] The optical lens of the first embodiment of the present invention and a laminated optical body including the optical film (cholesteric liquid crystal layer) of the first embodiment of the present invention may be combined with a lens and used as a composite lens. A virtual reality display device is a suitable example of a use of this composite lens. Below, the operation of the virtual reality display device will be explained in detail, and then the operation of the laminated optical body including the optical film (cholesteric liquid crystal layer) of the first embodiment of the present invention will be explained in detail.

[0054] FIG. 1 is a conceptual diagram of a virtual reality display device using a laminated optical body. The virtual reality display device shown in FIG. 1 includes an image display panel 500, a circular polarizer 400, a half mirror 300, a lens 200, and a laminated optical body 100. As described above, the laminated optical body 100 includes a cholesteric liquid crystal layer, a retardation layer, and a linear polarizer, in this order. In the virtual reality display device shown in FIG. 1, a light ray 1000 (display image) emitted from the image display panel 500 passes through the circular polarizer 400 to become circularly polarized light, and half of the light ray passes through the half mirror 300. The light ray 1000 that passes through the half mirror 300 then passes through the lens 200 and enters the laminated optical body 100 from the cholesteric liquid crystal layer side, where right-handed circularly polarized light or left-handed circularly polarized light is reflected. The circularly polarized light reflected by the cholesteric liquid crystal layer passes through the lens 200 again, is reflected again by the half mirror 300, and passes through the lens 200 again to enter the laminated optical body 100. Here, the circular polarization state of the light ray 1000 does not change when reflected by the laminated optical body (cholesteric liquid crystal layer), but when reflected by the half mirror 300, it changes to circular polarization that is orthogonal to the circular polarization when it first entered the laminated optical body 100. That is, right-handed circularly polarized light changes to left-handed circularly polarized light, and left-handed circularly polarized light changes to right-handed circularly polarized light. Therefore, the light ray 1000 reflected by the half mirror 300 passes through the laminated optical body 100 and is visually recognized by the user. Furthermore, when the light ray 1000 is reflected by the half mirror 300, the image is magnified due to the half mirror's concave mirror shape, allowing the user to visually recognize the magnified virtual image. Such an optical system is called a pancake lens (reciprocating optical system, folded optical system).

[0055] On the other hand, FIG. 2 is a schematic diagram illustrating a case where a light ray 1000 is unnecessarily transmitted without being reflected when it first enters the laminated optical body 100, resulting in leakage light 2000. Specifically, the leakage light 2000 is, for example, light that is unnecessarily transmitted without being reflected when the laminated optical body 100 (cholesteric liquid crystal layer) selectively reflects right-handed circularly polarized light when the right-handed circularly polarized light ray 100 first enters the laminated optical body 100. As shown in FIG. 2, in this case, the user will see leakage light 2000, which is an unmagnified image. This image is called a ghost or the like and should be reduced. A cholesteric liquid crystal layer does not inherently have a phase difference (in-plane retardation). However, in the virtual reality display device shown in FIGS. 1 and 2, the laminated optical body 100, i.e., the cholesteric liquid crystal layer, is formed in a concave mirror shape. As a result, the helical axis of the cholesteric liquid crystal layer changes partially in-plane, resulting in a phase difference. A cholesteric liquid crystal layer having a phase difference cannot properly reflect and transmit incident light. Therefore, when such a cholesteric liquid crystal layer is used in a pancake lens constituting a virtual reality display device, leakage light 2000, i.e., ghosting, increases. In contrast, the optical film (cholesteric liquid crystal layer) of the first embodiment of the present invention has a curved shape as described above. Furthermore, the evaluation wavelength (measurement wavelength) of the in-plane retardation is defined as a wavelength obtained by subtracting 20 nm from the half-maximum wavelength on the side shorter than the selective reflection center wavelength of the cholesteric liquid crystal layer. The in-plane retardation A at the evaluation wavelength at the center of the cholesteric liquid crystal layer is less than 2% of the evaluation wavelength, and the in-plane retardation B at the evaluation wavelength at the outer edge of the cholesteric liquid crystal layer is less than 2% of the evaluation wavelength. That is, the optical film of the first embodiment of the present invention has a small phase difference across the entire surface. Therefore, a virtual reality display device using a laminated optical body 100 including the optical film of the first embodiment of the present invention can suppress the occurrence of ghosting, despite using an optical film having a curved shape, i.e., a cholesteric liquid crystal layer. Moreover, such an optical film having a small retardation over the entire surface can be produced by the molding method of the first embodiment of the present invention, which will be described later.

[0056] FIG. 3 shows the layer structure of one embodiment of the laminated optical body 100. The laminated optical body 100 shown in FIG. 3 includes, in this order, an antireflection layer 101, a positive C plate 102, an optical film 103, a positive C plate 104, a retardation layer 105, and a linear polarizer 106. The optical film 103 is the optical film of the first embodiment of the present invention and is a cholesteric liquid crystal layer. The laminated optical body 100 includes, in this order, the optical film 103, a retardation layer 105 that converts circularly polarized light into linearly polarized light, and a linear polarizer 106. Here, the retardation layer 105 and the linear polarizer 106 are configured so that the optical film 103 converts circularly polarized light that would normally be reflected into linear polarizer light in the direction in which the linear polarizer absorbs it. According to the laminated optical body 100, leakage light from the optical film 103 (cholesteric liquid crystal layer) can be absorbed by the linear polarizer. Therefore, the degree of polarization of transmitted light can be increased. It should be noted that there is a concern that a phase difference may occur in the cholesteric liquid crystal layer when the laminated optical body is molded. However, as described above, the phase difference of the cholesteric liquid crystal layer of the first embodiment of the present invention remains small even after stretching or molding, and the amount of light leaking from the cholesteric liquid crystal layer is small, so the increase in leaked light is kept to a small amount.

[0057] As described above, the optical film of the first embodiment of the present invention may be composed of multiple cholesteric liquid crystal layers. Figure 4 shows an example of this configuration. This optical film 103 has, in order, a first light-reflecting layer (cholesteric liquid crystal layer) 31, a second light-reflecting layer 32, a third light-reflecting layer 33, and a fourth light-reflecting layer 34. An example of such an optical film 103 is the above-mentioned optical film having a blue light-reflecting layer with a reflectance of 40% or more at a wavelength of 460 nm, a green light-reflecting layer with a reflectance of 40% or more at a wavelength of 550 nm, a yellow light-reflecting layer with a reflectance of 40% or more at a wavelength of 600 nm, and a red light-reflecting layer with a reflectance of 40% or more at a wavelength of 650 nm.

[0058] Furthermore, the laminated optical body preferably has a surface roughness Ra of 100 nm or less. A small Ra is preferable because it can improve the sharpness of images, for example, when the laminated optical body is used in a virtual reality display device, etc. The inventors have estimated that when light is reflected from the laminated optical body, if there are irregularities, the angle of the reflected light is distorted, leading to distortion and blurring of the image. The Ra of the laminated optical body is preferably 50 nm or less, more preferably 30 nm or less, and even more preferably 10 nm or less. Furthermore, the laminated optical body is produced by stacking multiple layers. According to the inventors' studies, it has been found that stacking another layer on an irregular layer may amplify the irregularities. Therefore, it is preferable that the Ra of all layers in the laminated optical body is small. Each layer of the laminated optical body preferably has an Ra of 50 nm or less, more preferably 30 nm or less, and even more preferably 10 nm or less. Furthermore, from the viewpoint of improving the image sharpness of the reflected image, it is particularly preferable that the Ra of the cholesteric liquid crystal layer is small. The surface roughness Ra can be measured, for example, using a non-contact surface / layer cross-sectional shape measurement system, VertScan (manufactured by Ryoka Systems Co., Ltd.). Because VertScan is a surface shape measurement method that utilizes the phase of reflected light from a sample, when measuring a cholesteric liquid crystal layer, reflected light from within the film may be superimposed, making it impossible to accurately measure the surface shape. In this case, a metal layer may be formed on the surface of the sample to increase the surface reflectance and further suppress reflection from within. Sputtering is the main method used to form a metal layer on the surface of a sample. Examples of sputtering materials include Au, Al, and Pt.

[0059] It is preferable that the number of point defects per unit area of ​​the laminated optical body is small. Point defects lead to a decrease in the degree of polarization of transmitted light and a decrease in image sharpness, so it is preferable that they are small. Since the laminated optical body is produced by stacking many layers, it is preferable that the number of point defects in each layer is also small in order to reduce the number of point defects in the laminated optical body as a whole. Specifically, the number of point defects in each layer is preferably 20 or less per square meter, more preferably 10 or less, and even more preferably 1 or less. Furthermore, the number of point defects in the laminated optical body as a whole is preferably 100 or less per square meter, more preferably 50 or less, and even more preferably 5 or less. The number of point defects is preferably counted as the number of point defects with a size of 100 μm or more, more preferably 30 μm or more, and even more preferably 10 μm or more. Note that point defects include foreign matter, scratches, dirt, film thickness fluctuations, and poor alignment of liquid crystal compounds.

[0060] Furthermore, various sensors using near-infrared light as a light source for eye tracking, facial expression recognition, iris authentication, etc. may be incorporated into optical systems such as virtual reality display devices and electronic viewfinders. In this case, in order to minimize the influence on the sensors, it is preferable that the laminated optical body is transparent to near-infrared light.

[0061] [Retardation Layer] The retardation layer used in the laminated optical body has the function of converting the emitted light into approximately linearly polarized light when circularly polarized light is incident. As the retardation layer, for example, a retardation layer having an in-plane retardation Re of approximately 1 / 4 wavelength at any wavelength in the visible range can be used. As an example, the retardation layer preferably has an in-plane retardation Re (550) of 120 to 150 nm at a wavelength of 550 nm, more preferably 125 to 145 nm, and even more preferably 135 to 140 nm. In addition, a retardation layer having an Re of approximately 3 / 4 wavelength or approximately 5 / 4 wavelength is also preferable because it can convert linearly polarized light into circularly polarized light.

[0062] In addition, the retardation layer used in the laminated optical body preferably has reverse dispersion with respect to wavelength. If the retardation layer has reverse dispersion, it is possible to convert circularly polarized light into linearly polarized light over a wide wavelength range in the visible range, which is preferable. Here, having reverse dispersion with respect to wavelength means that the value of the retardation at that wavelength increases as the wavelength increases. A retardation layer having reverse dispersion can be produced by uniaxially stretching a polymer film such as a modified polycarbonate resin film having reverse dispersion, for example, with reference to JP 2017-049574 A. In addition, a retardation layer having reverse dispersion may be produced by substantially having reverse dispersion, for example, as disclosed in Japanese Patent No. 06259925 A, by laminating a retardation layer having an Re of approximately 1 / 4 wavelength and a retardation layer having an Re of approximately 1 / 2 wavelength so that their slow axes form an angle of approximately 60 °. In this case, it is known that even if the quarter-wave retardation layer and the half-wave retardation layer each have normal dispersion (the retardation value at the wavelength decreases as the wavelength increases), circularly polarized light can be converted into linearly polarized light over a wide wavelength range in the visible range, and they can be considered to have substantially reverse dispersion. In this case, it is preferable that the laminated optical body has a cholesteric liquid crystal layer, a quarter-wave retardation layer, a half-wave retardation layer, and a linear polarizer in this order.

[0063] In addition, it is also preferable that the retardation layer used in the laminated optical body has a layer formed by fixing a uniformly aligned liquid crystal compound. As such a retardation layer, for example, a layer in which a rod-shaped liquid crystal compound is uniformly aligned horizontally relative to the in-plane direction, and a layer in which a discotic liquid crystal compound is uniformly aligned perpendicularly to the in-plane direction, etc. can be used. Furthermore, for example, referring to JP-A-2020-084070, etc., a retardation layer having reverse dispersion properties, prepared by uniformly aligning and fixing a rod-shaped liquid crystal compound having reverse dispersion properties, can also be used.

[0064] In addition, the retardation layer used in the laminated optical body preferably has a layer formed by fixing a liquid crystal compound that is twisted and aligned with the thickness direction as the helical axis.For example, as disclosed in Japanese Patent No. 05753922 and Japanese Patent No. 05960743, a retardation layer can be used that has a layer formed by fixing a rod-shaped liquid crystal compound or a discotic liquid crystal compound that is twisted and aligned with the thickness direction as the helical axis.In this case, the retardation layer can be considered to have substantially reverse dispersion, so it is preferable.

[0065] The thickness of the retardation layer is not particularly limited, but from the viewpoint of thinning, it is preferably 0.1 to 8 μm, more preferably 0.3 to 5 μm.

[0066] The retardation layer may include a support, an alignment layer, and the like. The support and alignment layer may be a temporary support that is peeled off and removed when preparing the laminated optical body. Using a temporary support is preferable because the laminated optical body can be thinned by transferring the retardation layer to another laminate and then peeling off and removing the temporary support. Furthermore, the adverse effect of the retardation of the temporary support on the polarization degree of transmitted light can be eliminated. The type of support is not particularly limited, but a transparent support is preferred. For example, films such as cellulose acylate, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate, cyclic polyolefin, polyolefin, polyamide, polystyrene, and polyester can be used. Among these, cellulose acylate film, cyclic polyolefin, polyacrylate, and polymethacrylate are preferred. Commercially available supports can also be used. Examples of commercially available cellulose acetate films include "TD80U" and "Z-TAC" manufactured by Fujifilm Corporation. When the support is a temporary support, a support with high tear strength is preferred from the viewpoint of preventing breakage during peeling. From this viewpoint, polycarbonate and polyester films are preferred. Furthermore, the support preferably has a small phase difference from the viewpoint of suppressing adverse effects on the polarization degree of transmitted light. Specifically, the support preferably has an in-plane retardation of 10 nm or less, and the absolute value of the retardation Rth per thickness is preferably 50 nm or less. Furthermore, even if the support is used as the above-mentioned temporary support, it is preferable that the temporary support has a small phase difference in order to perform quality inspection of the retardation layer and other laminates in the manufacturing process of the laminated optical body.

[0067] In addition, various sensors using near-infrared light as a light source for eye tracking, facial expression recognition, iris authentication, etc. may be incorporated into optical systems such as virtual reality display devices and electronic viewfinders. In this case, in order to minimize the influence on the sensors, it is preferable that the retardation layer used in the laminated optical body is transparent to near-infrared light.

[0068] [Linear Polarizer] The linear polarizer used in the laminated optical body is an absorption polarizer that absorbs linearly polarized light in the absorption axis direction of incident light and transmits linearly polarized light in the transmission axis direction. A typical polarizer can be used as the linear polarizer. Examples include polarizers in which a dichroic material is dyed onto polyvinyl alcohol or other polymer resins and then oriented by stretching, and polarizers in which a dichroic material is oriented by utilizing the orientation of a liquid crystal compound. From the viewpoints of availability and increasing the degree of polarization, polarizers in which polyvinyl alcohol is dyed with iodine and then stretched are preferred. The thickness of the linear polarizer is preferably 10 μm or less, more preferably 7 μm or less, and even more preferably 5 μm or less. A thin linear polarizer can prevent cracking or breakage of the film when the laminated optical body is stretched or molded. The single-plate transmittance of the linear polarizer is preferably 40% or more, more preferably 42% or more. The degree of polarization is preferably 90% or more, more preferably 95% or more, and even more preferably 99% or more. In this specification, the single-plate transmittance and degree of polarization of the linear polarizer are measured using an automatic polarizing film measuring device: VAP-7070 (manufactured by JASCO Corporation). The direction of the transmission axis of the linear polarizer preferably coincides with the direction of the polarization axis of light converted into linearly polarized light by the retardation layer. For example, when the retardation layer is a layer having a retardation of ¼ wavelength, the angle between the transmission axis of the linear polarizer and the slow axis of the retardation layer is preferably approximately 45°.

[0069] The linear polarizer used in the laminated optical body is also preferably a light-absorbing anisotropic layer containing a liquid crystal compound and a dichroic material. A linear polarizer containing a liquid crystal compound and a dichroic material is preferable because it can be made thin and is less likely to crack or break even when stretched or molded. The thickness of the light-absorbing anisotropic layer is not particularly limited, but from the viewpoint of thinning, it is preferably 0.1 to 8 μm, more preferably 0.3 to 5 μm. A linear polarizer containing a liquid crystal compound and a dichroic material can be produced, for example, with reference to JP 2020-023153 A. From the viewpoint of improving the polarization degree of the linear polarizer, the light-absorbing anisotropic layer preferably has an orientation degree of the dichroic material of 0.95 or more, more preferably 0.97 or more.

[0070] When the linear polarizer is composed of a light-absorbing anisotropic layer containing a liquid crystal compound and a dichroic material, the linear polarizer may include a support, an alignment layer, etc. The support and alignment layer may be a temporary support that is peeled off and removed when preparing a laminated optical body. Using a temporary support is preferable because the laminated optical body can be thinned by transferring the light-absorbing anisotropic layer to another laminate and then peeling off and removing the temporary support. Furthermore, the adverse effect of the retardation of the temporary support on the polarization degree of transmitted light can be eliminated. The type of support is not particularly limited, but a transparent support is preferred. For example, films such as cellulose acylate, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate, cyclic polyolefin, polyolefin, polyamide, polystyrene, and polyester can be used. Among these, cellulose acylate film, cyclic polyolefin, polyacrylate, and polymethacrylate are preferred. Commercially available supports can also be used. Examples of commercially available cellulose acetate films include "TD80U" and "Z-TAC" manufactured by Fujifilm Corporation. When the support is a temporary support, a support with high tear strength is preferred in order to prevent breakage during peeling. In this respect, polycarbonate and polyester films are preferred. Furthermore, the support preferably has a small phase difference in order to suppress adverse effects on the polarization degree of transmitted light. Specifically, the support preferably has an in-plane retardation Re of 10 nm or less, and an absolute value of the thickness direction retardation Rth of 50 nm or less. Furthermore, even if the support is used as the temporary support described above, it is preferable that the temporary support have a small phase difference in order to perform quality inspections of the light-absorbing anisotropic layer and other laminates during the manufacturing process of the laminated optical body.

[0071] Furthermore, various sensors using near-infrared light as a light source for eye tracking, facial expression recognition, iris authentication, etc. may be incorporated into optical systems such as virtual reality display devices and electronic viewfinders. In this case, in order to minimize the influence on the sensors, it is preferable that the linear polarizer used in the laminated optical body is transparent to near-infrared light.

[0072] [Other Functional Layers] The laminated optical body may have other functional layers in addition to the cholesteric liquid crystal layer, the retardation layer, and the linear polarizer.

[0073] Furthermore, various sensors using near-infrared light as a light source for eye tracking, facial expression recognition, iris authentication, etc. may be incorporated into optical systems such as virtual reality display devices and electronic viewfinders. In this case, in order to minimize the influence on the sensors, it is preferable that other functional layers used in the laminated optical body are transparent to near-infrared light.

[0074] <Positive C Plate> As shown in FIG. 3, the laminated optical body preferably further includes a positive C plate. Here, the positive C plate is a retardation layer having an in-plane retardation Re of substantially zero and a negative retardation Rth in the thickness direction. The positive C plate can be obtained, for example, by vertically aligning a rod-shaped liquid crystal compound. For details of the manufacturing method of the positive C plate, see, for example, JP 2017-187732 A, JP 2016-53709 A, and JP 2015-200861 A. The positive C plate functions as an optical compensation layer to increase the degree of polarization of transmitted light with respect to obliquely incident light. The positive C plate can be installed at any position in the laminated optical body, and multiple positive C plates may be installed.

[0075] The positive C plate may be disposed adjacent to or within the cholesteric liquid crystal layer. For example, when a light-reflecting layer formed by fixing a cholesteric liquid crystal phase containing a rod-shaped liquid crystal compound is used as the cholesteric liquid crystal layer, the light-reflecting layer has a positive Rth. In this case, when light is incident obliquely onto the cholesteric liquid crystal layer, the Rth may change the polarization state of the reflected light and transmitted light, potentially reducing the degree of polarization of the transmitted light. Having a positive C plate within or near the cholesteric liquid crystal layer is preferable because it can suppress changes in the polarization state of obliquely incident light and reduce the degree of polarization of the transmitted light. According to the inventors' studies, the positive C plate is preferably disposed on the side of the blue light-reflecting layer opposite the green light-reflecting layer, but may be disposed elsewhere. In this case, the in-plane retardation Re of the positive C plate is preferably 10 nm or less, and the thickness-direction retardation Rth is preferably −600 to −100 nm, more preferably −400 to −200 nm.

[0076] Furthermore, in the laminated optical body, the positive C plate may be disposed adjacent to or inside the retardation layer. For example, when a layer formed by immobilizing a rod-shaped liquid crystal compound is used as the retardation layer, the retardation layer has a positive Rth. In this case, when light is incident on the retardation layer from an oblique direction, the polarization state of the transmitted light may change due to the action of Rth, and the degree of polarization of the transmitted light may decrease. Having a positive C plate inside or near the retardation layer is preferable because it can suppress changes in the polarization state of obliquely incident light and suppress a decrease in the degree of polarization of the transmitted light. According to the inventors' studies, the positive C plate is preferably disposed on the side of the retardation layer opposite the linear polarizer, but may be disposed elsewhere. In this case, the in-plane retardation Re of the positive C plate is preferably approximately 10 nm or less, and the thickness direction retardation Rth is preferably -90 to -40 nm.

[0077] <Anti-Reflection Layer> It is also preferable that the laminated optical body has an anti-reflection layer on its surface. The laminated optical body has the function of reflecting specific circularly polarized light and transmitting circularly polarized light orthogonal to it. However, reflection on the surface of the laminated optical body generally includes reflection of unintended polarized light, thereby reducing the polarization degree of the transmitted light. Therefore, it is preferable that the laminated optical body has an anti-reflection layer on its surface. The anti-reflection layer may be installed on only one surface of the laminated optical body or on both surfaces. The type of anti-reflection layer is not particularly limited, but from the viewpoint of further reducing the reflectance, moth-eye films and AR films are preferred. Furthermore, when the laminated optical body is stretched or molded, a moth-eye film is more preferred because it can maintain high anti-reflection performance even if the film thickness changes due to stretching. Furthermore, the anti-reflection layer may include a support. When the anti-reflection layer includes a support, when the laminated optical body is stretched and molded, from the viewpoint of facilitating stretching and molding, the support for the anti-reflection layer preferably has a Tg peak temperature of 170 ° C. or less, more preferably 130 ° C. or less. Specifically, the support is preferably, for example, a PMMA film.

[0078] <Second Retardation Layer> It is also preferable that the laminated optical body further has a second retardation layer. For example, the laminated optical body may include a cholesteric liquid crystal layer, a retardation layer, a linear polarizer, and a second retardation layer in this order. The second retardation layer preferably converts linearly polarized light into circularly polarized light, and for example, a retardation layer having a quarter wavelength Re is preferred. The reason for this will be explained below. Light that enters the laminated optical body from the cholesteric liquid crystal layer side and passes through the cholesteric liquid crystal layer, the retardation layer, and the linear polarizer becomes linearly polarized light, and a portion of it is reflected by the outermost surface on the linear polarizer side and then exits again from the surface on the cholesteric liquid crystal layer side. Such light is unnecessary reflected light and can be a factor in reducing the degree of polarization of the reflected light, so it is preferable to reduce it. Therefore, there is a method of laminating an antireflection layer to suppress reflection on the outermost surface on the linear polarizer side. However, when the laminated optical body is used by being attached to a medium such as glass or plastic, even if an antireflection layer is provided on the attachment surface of the laminated optical body, reflection on the surface of the medium cannot be suppressed, and therefore, the antireflection effect cannot be obtained. On the other hand, when a second retardation layer that converts linearly polarized light into circularly polarized light is provided, the light that reaches the outermost surface on the linear polarizer side becomes circularly polarized light and is converted into orthogonal circularly polarized light when reflected on the outermost surface of the medium. After that, when the light passes through the second retardation layer again and reaches the linear polarizer, the light becomes linearly polarized light in the absorption axis direction of the linear polarizer and is absorbed by the linear polarizer. Therefore, unnecessary reflection can be prevented. From the viewpoint of more effectively suppressing unnecessary reflection, it is preferable that the second retardation layer has substantially reverse dispersion.

[0079] <Support> The laminated optical body may further have a support. The support can be installed in any location. For example, when the cholesteric liquid crystal layer, the retardation layer, or the linear polarizer is a film to be transferred from a temporary support, the support can be used as the transfer destination. The type of support is not particularly limited, but it is preferably transparent. For example, films such as cellulose acylate, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate, cyclic polyolefin, polyolefin, polyamide, polystyrene, and polyester can be used. Among these, cellulose acylate film, cyclic polyolefin, polyacrylate, and polymethacrylate are preferred. Commercially available products can also be used as the support. Examples of commercially available products include cellulose acetate films such as "TD80U" and "Z-TAC" manufactured by Fujifilm Corporation. Furthermore, it is preferable that the support have a small retardation from the viewpoint of suppressing adverse effects on the polarization degree of transmitted light and facilitating optical inspection of the laminated optical body. Specifically, the in-plane retardation Re is preferably 10 nm or less, and the absolute value of the retardation Rth in the thickness direction is preferably 50 nm or less.

[0080] When the laminated optical body is to be stretched or molded, the support preferably has a tan δ peak temperature of 170° C. or less. From the viewpoint of enabling molding at low temperatures, the tan δ peak temperature is preferably 150° C. or less, and more preferably 130° C. or less.

[0081] Here, the method for measuring tan δ will be described. Using a dynamic viscoelasticity measuring device (e.g., DVA-200, manufactured by IT Measurement Control Co., Ltd.), a film sample is pre-conditioned for at least two hours in an atmosphere at a temperature of 25°C and a humidity of 60% Rh. E" (loss modulus) and E' (storage modulus) are measured under the following conditions, and tan δ (= E" / E') is the calculated value. Device: DVA-200, manufactured by IT Measurement Control Co., Ltd. Sample: 5 mm, length 50 mm (gap 20 mm) Measurement conditions: Tensile mode Measurement temperature: -150°C to 220°C Heating condition: 5°C / min Frequency: 1 Hz Note that, in general, resin substrates that have been subjected to a stretching treatment are often used in optical applications, and the peak temperature of tan δ often becomes high due to the stretching treatment. For example, the peak temperature of tan δ for a TAC (triacetyl cellulose) substrate (TG40, manufactured by Fujifilm Corporation) is 180°C or higher.

[0082] As a support having a tan δ peak temperature of 170°C or less, various resin substrates can be used without any particular limitation. Examples include polyolefins such as polyethylene, polypropylene, and norbornene-based polymers; cyclic olefin-based resins; polyvinyl alcohol; polyethylene terephthalate; acrylic resins such as polymethacrylic acid esters and polyacrylic acid esters; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyether ketone; polyphenylene sulfide, and polyphenylene oxide. Among these, preferred examples are cyclic olefin-based resins, polyethylene terephthalate, and acrylic resins, from the viewpoints of easy commercial availability and excellent transparency, and particularly preferred examples are cyclic olefin-based resins and polymethacrylic acid esters.

[0083] Examples of commercially available resin substrates include Technolloy S001G, Technolloy S014G, Technolloy S000, Technolloy C001, and Technolloy C000 (manufactured by Sumika Acrylic Sales Co., Ltd.), Lumirror U Type, Lumirror FX10, and Lumirror SF20 (manufactured by Toray Industries, Inc.), HK-53A (manufactured by Higashiyama Films Co., Ltd.), Teflex FT3 (manufactured by Teijin DuPont Films Co., Ltd.), S-Cina and SCA40 (manufactured by Sekisui Chemical Co., Ltd.), Zeonor Film (manufactured by Optes Co., Ltd.), and Arton Film (manufactured by JSR Corporation).

[0084] The thickness of the support is not particularly limited, but is preferably from 5 to 300 μm, more preferably from 5 to 100 μm, and even more preferably from 5 to 30 μm.

[0085] [Method of Adhesion of Each Layer] The laminated optical body is a laminate composed of multiple layers. Each layer can be adhered by any adhesion method. Adhesion can be performed using a pressure-sensitive adhesive or adhesive. Any commercially available pressure-sensitive adhesive can be used. Here, from the viewpoint of thinning and reducing the surface roughness Ra of the laminated optical body, the thickness of the pressure-sensitive adhesive is preferably 25 μm or less, more preferably 15 μm or less, and even more preferably 6 μm or less. Furthermore, it is preferable that the pressure-sensitive adhesive is less likely to outgas. In particular, when stretching and molding the laminated optical body, a vacuum process or a heating process may be performed, and it is preferable that the pressure-sensitive adhesive does not outgas even under these conditions. Any commercially available adhesive can be used as the adhesive. Examples of adhesives include epoxy resin-based adhesives and acrylic resin-based adhesives. From the viewpoint of thinning and reducing the surface roughness Ra of the laminated optical body, the thickness of the adhesive is preferably 25 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less. In addition, from the viewpoint of thinning the adhesive layer and applying the adhesive to the adherend with a uniform thickness, the viscosity of the adhesive is preferably 300 cP or less, more preferably 100 cP or less, and even more preferably 10 cP or less. Furthermore, when the adherend has surface irregularities, the adhesive or adhesive can be selected with an appropriate viscoelasticity or thickness so as to embed the surface irregularities of the layer to be adhered, in order to reduce the surface roughness Ra of the laminated optical body. From the viewpoint of embedding the surface irregularities, the adhesive or adhesive preferably has a viscosity of 50 cP or more. Furthermore, the thickness is preferably greater than the height of the surface irregularities. Examples of methods for adjusting the viscosity of the adhesive include using an adhesive containing a solvent. In this case, the viscosity of the adhesive can be adjusted by adjusting the ratio of the solvent. Furthermore, the thickness of the adhesive can be further reduced by applying the adhesive to the adherend and then drying the solvent.

[0086] In a laminated optical body, from the viewpoint of reducing unnecessary reflection and suppressing a decrease in the degree of polarization of transmitted light and reflected light, it is preferable that the pressure-sensitive adhesive or adhesive used to bond each layer has a small refractive index difference with adjacent layers. Specifically, the refractive index difference between adjacent layers is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.01 or less. The refractive index of the pressure-sensitive adhesive or adhesive can be adjusted, for example, by mixing titanium oxide fine particles or zirconia fine particles. Furthermore, the cholesteric liquid crystal layer, retardation layer, and linear polarizer have in-plane refractive index anisotropy, but it is preferable that the refractive index difference with adjacent layers in all directions in the plane is 0.05 or less. Therefore, the pressure-sensitive adhesive or adhesive may have in-plane refractive index anisotropy.

[0087] Furthermore, the adhesive layer between each layer preferably has a thickness of 100 nm or less. When the adhesive layer has a thickness of 100 nm or less, the refractive index difference is less noticeable for visible light, thereby suppressing unnecessary reflection. The adhesive layer preferably has a thickness of 50 nm or less. An example of a method for forming an adhesive layer having a thickness of 100 nm or less is a method of depositing a ceramic adhesive such as a silicon oxide (SiOx layer) on the bonding surface. The bonding surface of the bonding member may be subjected to a surface modification treatment such as plasma treatment, corona treatment, or saponification treatment before bonding. A primer layer may also be provided on the bonding surface of the bonding member. Furthermore, when there are multiple bonding surfaces, the type and thickness of the adhesive layer can be adjusted for each bonding surface. Specifically, an adhesive layer having a thickness of 100 nm or less can be provided by the following steps (1) to (3): (1) The layers to be laminated are attached to a temporary support made of a glass substrate. (2) A SiOx layer having a thickness of 100 nm or less is formed on both the surface of the layer to be laminated and the surface of the layer to be laminated by vapor deposition or the like. Vapor deposition can be performed using, for example, a vapor deposition device manufactured by ULVAC (model number ULEYES) using SiOx powder as the vapor deposition source. It is also preferable to subject the surface of the formed SiOx layer to plasma treatment. (3) After the formed SiOx layers are bonded together, the temporary support is peeled off. The bonding is preferably performed at a temperature of, for example, 120°C.

[0088] The coating, adhesion, or lamination of each layer may be performed by roll-to-roll or sheet-to-sheet. The roll-to-roll method is preferred from the viewpoints of improving productivity and reducing axial misalignment of each layer. On the other hand, the sheet-to-sheet method is preferred from the viewpoints of being suitable for small-lot, high-mix production and being able to select a special adhesion method such as the above-mentioned adhesive layer having a thickness of 100 nm or less. Examples of methods for applying the adhesive to the adherend include known methods such as roll coating, gravure printing, spin coating, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, die coating, spraying, and inkjet printing.

[0089] [Direct Coating of Each Layer] It is also preferable that there is no adhesive layer between each layer of the laminated optical body. When forming a layer, the adhesive layer can be eliminated by directly coating the layer on an adjacent layer that has already been formed. Furthermore, when one or both of the adjacent layers contain a liquid crystal compound, it is preferable that the alignment direction of the liquid crystal compound continuously changes at the interface in order to reduce the refractive index difference in all in-plane directions. For example, a retardation layer containing a liquid crystal compound can be directly coated on a linear polarizer containing a liquid crystal compound and a dichroic material, and the liquid crystal compound of the retardation layer can be continuously aligned at the interface due to the alignment control force of the liquid crystal compound of the linear polarizer.

[0090] [Lamination Order of Layers] The laminated optical body is composed of many layers, but the order of the lamination process is not particularly limited and can be selected arbitrarily. For example, when transferring a functional layer from a film consisting of a temporary support and a functional layer, the occurrence of wrinkles, cracks, etc. during transfer can be suppressed by adjusting the lamination order so that the thickness of the transferred film is 10 μm or more. In addition, when a laminated optical body is laminated on a layer with large surface irregularities, the surface irregularities may be further amplified. Therefore, from the viewpoint of reducing the surface roughness Ra of the laminated optical body, it is preferable to laminate the layers in order from the layer with the smallest surface roughness Ra. Furthermore, the lamination order can also be selected from the viewpoint of quality evaluation in the manufacturing process of the laminated optical body. For example, layers other than the cholesteric liquid crystal layer can be laminated and quality evaluation can be performed using a transmission optical system, and then the cholesteric liquid crystal layer can be laminated and quality evaluation can be performed using a reflection optical system. The lamination order can also be selected from the viewpoint of improving the manufacturing yield of the laminated optical body and reducing costs.

[0091] The second aspect of the optical film of the first embodiment of the present invention is not a cholesteric liquid crystal layer but a film that does not have selective reflectivity. A laminated optical body using this optical film can use various known optical elements, and the above-mentioned description applies to each optical element.

[0092] <Composite Lens> One embodiment of the composite lens includes a lens and the optical film of the first embodiment of the present invention. Alternatively, one embodiment of the composite lens includes a lens and a laminated optical body including the optical film of the first embodiment of the present invention. As shown in FIG. 1, a half mirror may be formed on one side of the lens. The lens may be a convex or concave lens. The convex lens may be a biconvex lens, a plano-convex lens, or a convex meniscus lens. The concave lens may be a biconcave lens, a plano-concave lens, or a concave meniscus lens. Preferred examples of lenses used in virtual reality display devices include convex meniscus lenses and concave meniscus lenses, which increase the viewing angle. Furthermore, concave meniscus lenses are more preferred because they minimize chromatic aberration. Materials that are transparent to visible light, such as glass, crystal, and plastic, can be used to form the lens. Because birefringence in lenses can cause rainbow irregularities and light leakage, a small birefringence is preferable, and zero-birefringence materials are more preferred.

[0093] 1, one embodiment of a virtual reality display device includes an image display panel that emits at least polarized light and a compound lens that includes the optical film of the first embodiment of the present invention. The virtual reality display device may also include additional optical components such as a half mirror or a diopter adjustment lens.

[0094] <Image Display Panel> In the virtual reality display device using the optical film of the first embodiment of the present invention, a known image display device can be used as the image display panel (image display device). Specifically, examples of the image display panel include display devices in which self-luminous fine light emitters are arranged on a transparent substrate, such as organic electroluminescence display devices, LED (Light Emitting Diode) display devices, and micro-LED display devices. These self-luminous display devices typically have a (circular) polarizing plate attached to the display surface to prevent reflection on the display surface. Therefore, the emitted light is polarized. Another example of an image display device is a liquid crystal display device. Liquid crystal display devices also have a polarizing plate on their surface, so the emitted light is polarized. In the following description, an organic electroluminescence display device is also referred to as an OLED. OLED is an abbreviation for "organic light emitting diode."

[0095] <Molding Method> As described above, the optical film of the first embodiment of the present invention has a curved surface shape of a non-developable surface with a positive Gaussian curvature, such as a spherical surface, a parabolic surface, an ellipsoidal surface, or an aspherical surface. An optical film (laminated optical body) having such a curved surface shape is formed by preparing a planar optical film, pressing the optical film against a mold to mold it into a curved shape, and finally cutting the molded optical film into the desired shape of the optical element, such as a circular lens having a circular planar shape. The molding method (molding method) of the first embodiment of the present invention for molding a planar optical film into such a curved optical film includes a step of heating the optical film or the mold (heating step), a step of pressing the heated optical film against the mold to deform it according to the shape of the mold (molding step), and a step of cutting the molded optical film (cutting step). The molding method described below also includes molding a laminated optical body including the optical film of the first embodiment of the present invention. In the following description, the planar optical film to be molded into a curved shape will also be referred to as the "film to be molded" for convenience.

[0096] [Heating Step (Step of Heating Optical Film)] In the heating step, the method for heating the film to be formed is not limited, and various known methods can be used. Examples include heating by contact with a heated solid, heating by contact with a heated liquid, heating by contact with a heated gas, heating by infrared radiation, and heating by microwave radiation. Among these, heating by infrared radiation is preferred because it allows heating to be performed remotely just before forming. In the heating step, the mold may be heated instead of the film to be formed. In this case, the mold may also be heated by a known method.

[0097] The wavelength of the infrared rays used for heating is not limited, but is preferably 1.0 to 30.0 μm, and more preferably 1.5 to 5 μm. Examples of infrared light sources (IR light sources) include near-infrared lamp heaters with a tungsten filament inserted in a quartz tube, and wavelength-controlled heaters with multiple quartz tubes and a mechanism for cooling a portion of the space between the quartz tubes with air. Furthermore, by distributing the amount of infrared radiation irradiated onto the film to be molded, the physical properties during molding can be controlled according to the purpose. Known methods can be used to impart a distribution (intensity distribution) to the amount of infrared radiation irradiated. Examples include a method of varying the density of IR light sources, and a method of placing a filter with a patterned transmittance for infrared light between the IR light source and the film to be molded. Examples of filters with patterned transmittance include filters in which metal is vapor-deposited on glass, filters with a cholesteric liquid crystal layer that selectively reflects infrared light in a wavelength band, filters with a dielectric multilayer film that selectively reflects infrared light in a wavelength band, and filters coated with ink that absorbs infrared light. In the heating process, the temperature of the film to be formed can be controlled by controlling the amount of infrared light irradiated. Examples include a method of controlling the infrared light irradiation time and a method of controlling the illuminance of the infrared light irradiated. The temperature of the film to be formed can be monitored using, for example, a non-contact radiation thermometer and a thermocouple, and can be adjusted to the desired temperature.

[0098] In the heating step, the mold may be heated instead of the film to be formed. In this case, the mold may also be heated by a known method.

[0099] [Molding step (a step of pressing the moldable film against the mold and deforming it to conform to the mold shape)] In the molding step, examples of a method of pressing the moldable film against the mold and deforming it to conform to the mold shape include, for example, reducing the pressure in the molding space and applying pressure, when the mold has a concave surface. Also, when the mold has a convex surface, a method of pressing the mold can be used.

[0100] [Step of Cutting Optical Film] The molded optical film can be cut into any desired shape using a cutter, scissors, a cutting plotter, a laser cutter, or the like.

[0101] The curved optical film of the first embodiment of the present invention is formed by molding a cholesteric liquid crystal layer or an optical film without selective reflectivity into a curved shape. The cholesteric liquid crystal layer basically does not have a phase difference (in-plane retardation). In addition, in the present invention, the optical film without selective reflectivity is preferably an optical film with a small phase difference made of a low birefringence polymer resin, specifically an optical film with an in-plane retardation of less than 11 nm at a wavelength of 550 nm. In addition, in the present invention, unless otherwise specified, the phase difference refers to an in-plane phase difference (phase difference in the in-plane direction). Here, according to the studies of the present inventors, when such an optical film (film to be molded) is heated and molded into a curved shape, the amount and direction of stretching vary partially, resulting in an in-plane phase difference.

[0102] As an example, as conceptually shown in FIG. 6 , a case will be described in which a film F to be molded is pressed against a spherical, concave mold M to be molded. When such molding is performed, the optical film F after molding has different stretching states between the center and the outer edge (edge). Specifically, in this case, the optical film F is stretched in both the circumferential and radial directions at the center. In contrast, the optical film F, i.e., at the outer edge of the spherical mold M, is stretched only in the radial direction, with almost no circumferential stretching. That is, in this case, the optical film F is stretched uniformly over the entire center, whereas the outer edge is stretched only in one direction, the radial direction. This non-uniformity in the amount of stretching increases from the center to the outer edge. In other words, when the optical film is molded into a curved shape by pressing it against the mold M, the optical film is stretched isotropically at the center, but is anisotropically stretched at the outer edge, i.e., the edge. Moreover, the anisotropy of the stretching gradually increases from the center toward the edges.

[0103] As a result, in a cholesteric liquid crystal layer, the change in the helical axis is small in the central portion, but the helical axis changes at and near the outer edge, resulting in a phase difference. A cholesteric liquid crystal layer with a phase difference cannot properly reflect or transmit incident light. Therefore, as mentioned above, when such a cholesteric liquid crystal layer is used in a pancake lens constituting a virtual reality display device, unwanted images, known as ghosts (leakage light), are observed, and this phenomenon increases. Furthermore, even in so-called low-retardation (zero-retardation) films, if the central portion is uniformly stretched in the in-plane direction and the outer edge is significantly stretched only in the diameter direction, the balance of the optical properties of the film is lost at and near the outer edge. As a result, a phase difference is generated, and the optical film having a molded curved shape exhibits in-plane phase difference variation, reducing its function as a low-retardation film.

[0104] In contrast, according to the molding method of the first embodiment of the present invention, it is possible to suppress the occurrence of phase difference when a flat optical film (film to be molded) is heated and pressed against a mold to be molded into a curved shape. As a result, according to the molding method of the first embodiment of the present invention, as described above, it is possible to produce the optical film of the first embodiment of the present invention, which is made of a cholesteric liquid crystal layer having a curved shape or a film having a curved shape and no selective reflectivity, and which has a small phase difference, i.e., in-plane retardation, all over the surface.

[0105] The molding method of the first embodiment of the present invention will be described below. As described above, the molding method of the first embodiment of the present invention includes a heating step of heating a planar optical film (molded film), a molding step of pressing the heated molded film against a mold and deforming it along the mold to form a curved shape, and a cutting step of cutting the molded optical film. In a first aspect of the molding method of the first embodiment of the present invention, in the heating step of such a molding method, the molded film is heated by irradiating it with infrared rays, and an in-plane distribution is provided in the amount of infrared irradiation. In other words, in the first aspect of the molding method of the first embodiment of the present invention, in heating the molded film by irradiating it with infrared rays, an in-plane distribution is provided in the amount of heat of the molded film, i.e., the temperature of the molded film after heating. More specifically, in a preferred embodiment, a first aspect of the molding method of the first embodiment of the present invention uses a mold having a non-developable concave surface with a positive Gaussian curvature, and when the in-plane position of the optical film is projected onto the mold from the normal direction of the main surface of the molded film, the amount of infrared radiation irradiated onto the molded film at the apex (bottom) of the concave surface is greater than the amount of infrared radiation irradiated onto the molded film at the end, i.e., outer edge, of the concave surface. In other words, in the first aspect of the molding method of the first embodiment of the present invention, when heating the molded film by infrared radiation, the temperature of the apex of the concave surface of the mold, i.e., the center of the molded film after molding, is higher than the outer edge (end). Note that the main surface refers to the largest surface of a sheet-like object (film, plate-like object, layer) and is usually both sides in the thickness direction. In addition, the normal direction refers to the direction perpendicular to the main surface of the sheet-like object.

[0106] In molding by pressing against a mold, deformation, i.e., stretching, of the film to be molded is usually easier at higher temperatures. That is, in the first aspect of the molding method of the first embodiment of the present invention, the temperature of the central portion of the film to be molded is made higher than that of the outer edge portion, so that most of the molding, i.e., stretching, is performed in the central portion, which is stretched evenly in the plane direction. Therefore, after being molded into a curved shape, most of the optical film can be a region where no retardation occurs and is stretched evenly in the plane direction. As a result, according to the first aspect of the molding method of the first embodiment of the present invention, it is possible to produce the optical film of the first embodiment of the present invention, which has a small retardation, i.e., in-plane retardation, throughout the entire surface.

[0107] In the first aspect of the molding method of the first embodiment of the present invention, there is no limitation on the temperature difference between the center and end portions of the molded film (mold), and it may be set appropriately depending on the material of the molded film (laminated optical body before molding). One example is a method in which the temperature of the center portion is set to Tg or higher and the temperature of the end portions is set to lower than Tg, depending on the Tg (glass transition temperature) of the layer that mainly controls the stretching of the molded film. This makes it possible to achieve greater deformation of the center portion that is stretched evenly in the plane direction. Furthermore, in the first aspect of the molding method of the first embodiment of the present invention, the change in the amount of infrared radiation irradiated between the center portion and the end portions, i.e., the temperature change, may be either stepwise or continuous. Note that, in the first aspect of the molding method of the first embodiment of the present invention, known methods can be used to differentiate the amount of infrared radiation irradiated between the center portion and the end portions. Examples include the above-mentioned method of varying the density of the light source arrangement, and a method of placing a filter with a patterned transmittance to infrared light between the light source and the molded film.

[0108] In a second aspect of the molding method of the first embodiment of the present invention, in molding an optical film having the heating step, molding step, and cutting step as described above, the surface of the mold that contacts the optical film (film to be molded) is a non-developable concave surface with a positive Gaussian curvature, and the outer periphery is an ellipse. Then, in the cutting step, the optical film is cut into an ellipse, and the major axis of the elliptical outer periphery of the optical film cut out by cutting is set to be greater than 50% and less than 95% of the major axis of the elliptical outer periphery of the mold. As described above, in the present invention, an ellipse includes a circle.

[0109] That is, in the second aspect of the molding method of the first embodiment of the present invention, the heating step and molding step are performed using a planar film to be molded and a large mold that are larger than the optical film having a curved shape to be produced. Then, in the cutting step, only the central portion of the optical film, i.e., the portion that has been pressed against the central portion of the mold and molded, i.e., stretched, is cut out. Therefore, in the second aspect of the molding method of the first embodiment of the present invention, most of the optical film after cutting and molded into a curved shape has a region that is uniformly stretched in the plane direction and does not have a phase difference. As a result, the optical film of the present invention having a small phase difference, i.e., a small in-plane retardation, can be produced in the second aspect of the molding method of the first embodiment of the present invention.

[0110] In a second aspect of the molding method of the first embodiment of the present invention, the major axis of the elliptical outer periphery of the optical film cut out in the cutting step is greater than 50% and less than 95% of the major axis of the elliptical outer periphery of the mold. If the major axis of the cut optical film is 50% or less of the major axis of the elliptical outer periphery of the mold, the optical film will be wasted, which is a disadvantage. If the major axis of the cut optical film is 95% or more of the major axis of the elliptical outer periphery of the mold, many regions will have significantly different amounts of stretching in the circumferential and radial directions, making it impossible to obtain an optical film with a curved surface and sufficiently small retardation throughout. In the second aspect of the molding method of the first embodiment of the present invention, the major axis of the elliptical outer periphery of the optical film cut out in the cutting step is preferably 60 to 90%, more preferably 70 to 90%, of the major axis of the elliptical outer periphery of the mold.

[0111] In a third aspect of the molding method of the first embodiment of the present invention, in molding an optical film having a heating step, a molding step, and a cutting step as described above, in the heating step, the region of the optical film (film to be molded) that contacts the mold is heated to a temperature higher than the glass transition temperature Tg of the film to be molded, and in the molding step, the pressing of the film to be molded against the mold is controlled so that the region of the film to be molded that contacts the mold becomes lower than the glass transition temperature Tg immediately after the film to be molded contacts the mold. Note that in this molding method, when a laminated optical body including an optical film is molded, that is, when the laminated optical body including the optical film is a film to be molded, temperature control is performed with the glass transition temperature Tg of the member with the highest rigidity, such as a support, as the target.

[0112] For example, if the mold has a concave surface, when a planar optical film (film to be formed) is pressed against the mold, the film contacts the edges of the mold first, and finally the center contacts the top (bottom) of the concave surface. Furthermore, unless heating or the like is performed, the temperature of the mold is lower than the temperature of the film to be formed for forming. That is, in the third aspect of the forming method of the first embodiment of the present invention, during the forming process, the film to be formed is formed by pressing it against the mold while the center remains in a state where its temperature is above Tg and is easily stretched, and the region in contact with the mold is in a state where it is difficult to stretch. Therefore, even in the third aspect of the forming method of the first embodiment of the present invention, most of the forming, i.e., stretching, is performed in the center, which is stretched evenly in the plane direction, and the optical film after being formed into a curved shape can have a region that is stretched evenly in the plane direction and does not exhibit phase difference. As a result, according to the third aspect of the forming method of the first embodiment of the present invention, the optical film of the first embodiment of the present invention, which has a small phase difference, i.e., in-plane retardation, can be produced.

[0113] In the third aspect of the molding method of the first embodiment of the present invention, various methods can be used to control the pressing of the molded film so that the region in contact with the mold becomes lower than the glass transition temperature Tg immediately after the molded film comes into contact with the mold in the molding step. One example is a control method in which, after heating the molded film in the heating step, the speed at which the molded film is pressed against the mold is adjusted so that the region in contact with the mold becomes lower than the glass transition temperature Tg.

[0114] A fourth aspect of the molding method of the first embodiment of the present invention includes a heating step of heating a mold, a molding step of pressing the heated mold against an optical film (a film to be molded) to deform the film to conform to the shape of the mold, and a cutting step of cutting the optical film. In this fourth aspect of the molding method of the first embodiment of the present invention, the mold has a non-developable convex surface with a positive Gaussian curvature, and in the molding step, the film to be molded is molded by pressing the apex of the convex surface of the mold against the center of the film to be molded. Preferably, the cut shape of the optical film in the cutting step is an ellipse, and further, in the molding step, the film to be molded is pressed against the mold while being constrained in position on the elliptical line that will become the cut shape.

[0115] That is, in the fourth aspect of the molding method of the first embodiment of the present invention, a heated mold is pressed against the center of an optical film (a film to be molded) to mold it into a curved shape. This initially increases the temperature of the central portion of the film to make it more stretchable, and as the pressing by the mold progresses, the higher-temperature region spreads toward the edges. Therefore, in the fourth aspect of the molding method of the first embodiment of the present invention, most of the molding, i.e., stretching, is performed in the central portion, which is uniformly stretched in the in-plane direction. Therefore, after being molded into a curved shape, the optical film can have a region uniformly stretched in the in-plane direction where no retardation occurs. Preferably, molding is performed by pressing the mold against the film to be molded while restraining the edges, thereby suppressing stretching near the edges, where stretching is anisotropic and retardation is likely to occur, and more favorably, most of the molding, i.e., stretching, can be performed in the central portion. As a result, according to the fourth aspect of the molding method of the first embodiment of the present invention, an optical film of the first embodiment of the present invention having a small retardation, i.e., in-plane retardation, can be produced.

[0116] In the fourth aspect of the molding method of the first embodiment of the present invention, the method for restraining the end of the molded film is not limited, and various methods can be used. Examples include a method in which a peelable adhesive sheet or the like is used to attach the vicinity of the end of the molded film to a support table that supports the molded film to be molded by pressing a convex mold, and a method in which a jig or the like is used to fix the vicinity of the end of the molded film to a support table that supports the molded film to be molded by pressing a convex mold.

[0117] <Molding Apparatus> The optical film molding apparatus for carrying out the molding method of the first embodiment of the present invention is not limited, and molding apparatuses with various configurations can be used. One form of molding apparatus includes a box 1 having an opening on its top surface and a box 2 having an opening on its bottom surface. To form a molding space, the openings of box 1 and box 2 are aligned directly or via other jigs to form a sealed molding space. A planar optical film to be molded (film to be molded) and a mold for molding this optical film are placed within the molding space. When the optical film (laminated optical body) of the first embodiment of the present invention is attached to a lens to form the above-described composite lens, a lens such as a concave lens may be used as the mold, and the optical film molded into a curved shape may be directly attached to the mold. The molding apparatus is provided with a heating means, such as an IR light source, for heating the film to be molded. Multiple heating means may be arranged in a distributed manner. The heating means may be placed within the molding space, or may be placed outside the molding space and irradiate the film to be molded with heat rays such as infrared rays through a transparent window. The film to be formed is arranged as a partition, dividing the forming space consisting of box 1 and box 2 into two spaces. The mold is arranged inside box 1 below the film to be formed. In this state, the pressure inside boxes 1 and 2 is reduced to a predetermined pressure, the film to be formed is heated, and then the pressure inside box 2 is increased (the degree of vacuum is reduced) to press the film to be formed against the mold.

[0118] Second Embodiment <Cholesteric Liquid Crystal Layer (Optically Functional Layer)> A cholesteric liquid crystal layer (optically functional layer) according to a second embodiment of the present invention is an optically functional layer containing a liquid crystalline compound, the cholesteric liquid crystal layer having a retardation region in which the retardation increases from the center to the outside, and in the retardation region, the direction of the slow axis at a point in the retardation region is perpendicular to the direction from the center toward the point.

[0119] The optical laminate of the second embodiment of the present invention is an optical laminate having a plurality of the above-mentioned cholesteric liquid crystal layers. The cholesteric liquid crystal layer and the optical laminate of the second embodiment of the present invention may be used alone or may be laminated with other functional layers such as a support and an alignment film to be used as an optical film.

[0120] [Cholesteric Liquid Crystal Phase] Cholesteric liquid crystal phases are known to exhibit selective reflectivity at specific wavelengths. In a typical cholesteric liquid crystal phase, the central wavelength of selective reflection (selective reflection central wavelength) λ depends on the helical pitch P of the cholesteric liquid crystal phase and follows the relationship λ = n × P with the average refractive index n of the cholesteric liquid crystal phase. Therefore, the selective reflection central wavelength can be adjusted by adjusting this helical pitch. The longer the pitch P, the longer the selective reflection central wavelength of the cholesteric liquid crystal phase. Note that, as described above, the helical pitch P is one pitch (helical period) of the helical structure of the cholesteric liquid crystal phase, in other words, one helical turn, i.e., the length of the helical axis direction in which the director (long axis direction in the case of rod-shaped liquid crystals) of the liquid crystal compound constituting the cholesteric liquid crystal phase rotates 360°.

[0121] When a cross section of a cholesteric liquid crystal layer is observed with a scanning electron microscope (SEM), a striped pattern with alternating bright and dark lines (bright areas) in the thickness direction is observed, which is due to the cholesteric liquid crystal phase. The helical period pitch, or pitch P, is equal to the length of two bright lines and two dark lines in the thickness direction, i.e., the length of two dark lines and two bright lines in the thickness direction.

[0122] The helical pitch of a cholesteric liquid crystal phase depends on the type and concentration of the chiral dopant used together with the liquid crystal compound when forming the cholesteric liquid crystal layer. Therefore, the desired helical pitch can be obtained by adjusting these factors. Details on pitch adjustment are provided in Fujifilm Research Report No. 50 (2005), pp. 60-63. Methods for measuring the helical sense and pitch can be found in "Introduction to Liquid Crystal Chemistry Experiments," edited by the Japanese Liquid Crystal Society, published by Sigma Publishing in 2007, p. 46, and "Liquid Crystal Handbook," published by the Liquid Crystal Handbook Editorial Committee, Maruzen, p. 196.

[0123] Cholesteric liquid crystal phases exhibit selective reflection for either left- or right-handed circularly polarized light at a specific wavelength. Whether the reflected light is right-handed or left-handed circularly polarized depends on the helical twist (sense) of the cholesteric liquid crystal phase. The selective reflection of circularly polarized light by a cholesteric liquid crystal phase reflects right-handed circularly polarized light when the helical twist direction of the cholesteric liquid crystal layer is right-handed, and reflects left-handed circularly polarized light when the helical twist direction is left-handed. Therefore, the helical twist direction of a cholesteric liquid crystal phase can be confirmed by irradiating the cholesteric liquid crystal layer with right-handed and / or left-handed circularly polarized light. The rotation direction of the cholesteric liquid crystal phase can be adjusted by the type of liquid crystal compound forming the cholesteric liquid crystal layer and / or the type of chiral agent added.

[0124] Furthermore, the half-width Δλ (nm) of the selective reflection wavelength range (circularly polarized light reflection wavelength range) exhibiting selective reflection depends on the Δn of the cholesteric liquid crystal phase and the helical pitch P, and follows the relationship Δλ = Δn × P. Therefore, the width of the selective reflection wavelength range (selective reflection wavelength range) can be controlled by adjusting Δn. Δn can be adjusted by the type and mixing ratio of the liquid crystal compounds forming the cholesteric liquid crystal layer, as well as the temperature during alignment fixation.

[0125] [Cholesteric Liquid Crystal Layer] As is well known, a cholesteric liquid crystal layer is a layer formed by fixing a cholesteric liquid crystal phase in which liquid crystal compounds are helically cholesterically aligned. The cholesteric liquid crystal layer has a selective reflection center wavelength determined by the helical pitch of the cholesteric liquid crystal phase, and reflects light in a wavelength range including the selective reflection center wavelength and transmits light in other wavelength ranges.

[0126] Here, a typical cholesteric liquid crystal layer has no in-plane refractive index difference and has an in-plane retardation of approximately 0. In contrast, in the present invention, the cholesteric liquid crystal layer is configured to have a region (retardation region) in which the in-plane refractive index nx in the slow axis direction and the refractive index ny in the fast axis direction satisfy nx > ny, so that the cholesteric liquid crystal layer exhibits front retardation (in-plane retardation). Furthermore, in the present invention, the cholesteric liquid crystal layer has a configuration in which the retardation increases from the center to the outside in this retardation region, and the direction of the slow axis at a point in the retardation region is perpendicular to the direction from the center toward this point.

[0127] A cholesteric liquid crystal layer having a region that satisfies nx>ny will be described below.

[0128] 7 conceptually shows an example of such a cholesteric liquid crystal layer. The cholesteric liquid crystal layer 126 is formed on an alignment film 124 that is formed on a support 120. In the following description, the support 120 side is also referred to as the bottom, and the cholesteric liquid crystal layer 126 side is also referred to as the top. Therefore, in the support 120, the cholesteric liquid crystal layer 126 side is also referred to as the top surface, and the opposite side is also referred to as the bottom surface. In addition, in the alignment film 124 and the cholesteric liquid crystal layer 126, the surface on the support 120 side is also referred to as the bottom surface, and the opposite side is also referred to as the top surface.

[0129] The support 120 supports the cholesteric liquid crystal layer 126 when it is formed. When the support 120 is a temporary support, various temporary supports used when producing a cholesteric liquid crystal layer are exemplified. For example, the temporary support is a film-like member made of glass, triacetyl cellulose (TAC), polyethylene terephthalate (PET), polycarbonate, polyvinyl chloride, acrylic, polyolefin, or the like. Alternatively, the support may be a multilayer support having multiple layers made of these materials.

[0130] The alignment film 124 is formed on the surface (upper surface) of the support 120. The alignment film 124 is an alignment film for orienting the liquid crystal compound 132 in a predetermined alignment state when the cholesteric liquid crystal layer 126 is formed.

[0131] Various known materials can be used as the alignment film 124. Examples include a rubbed film made of an organic compound such as a polymer, an obliquely evaporated film of an inorganic compound, a film having microgrooves, a film in which LB (Langmuir-Blodgett) films made of organic compounds such as ω-tricosanoic acid, dioctadecylmethylammonium chloride, and methyl stearate are accumulated by the Langmuir-Blodgett method, and a photo-alignment film formed by irradiating polarized or unpolarized light onto a photo-alignment material.

[0132] The alignment film 124 may be formed by a known method depending on the material used to form the alignment film. For example, an alignment film formed by rubbing can be formed by rubbing the surface of a polymer layer several times in a certain direction with paper or cloth. Materials used for the alignment film include polyimide, polyvinyl alcohol, polymers having polymerizable groups as described in Japanese Patent Application Laid-Open No. 9-152509, and materials used to form alignment films as described in Japanese Patent Application Laid-Open Nos. 2005-97377, 2005-99228, and 2005-128503. Alternatively, the support 120 may function as an alignment film by subjecting the support 120 to rubbing, laser processing, or other processes without forming the alignment film 124.

[0133] The alignment film 124 may be a so-called photo-alignment film obtained by irradiating a photo-alignment material with polarized or non-polarized light to form the alignment film 124. That is, a photo-alignment film formed by applying a photo-alignment material onto the support 120 is preferably used as the alignment film 124. The photo-alignment film may be irradiated with polarized light from a vertical direction or an oblique direction, and the photo-alignment film may be irradiated with non-polarized light from an oblique direction.

[0134] Examples of photo-alignment materials used in the alignment film that can be used in the present invention include those disclosed in JP-A-2006-285197, JP-A-2007-76839, JP-A-2007-138138, JP-A-2007-94071, JP-A-2007-121721, JP-A-2007-140465, JP-A-2007-156439, and JP-A-2007 azo compounds described in JP-A-133184, JP-A-2009-109831, Japanese Patent Nos. 3,883,848 and 4,151,746; aromatic ester compounds described in JP-A-2002-229039; maleimides having photo-orientable units described in JP-A-2002-265541 and JP-A-2002-317013; / or alkenyl-substituted nadimide compounds, photocrosslinkable silane derivatives described in Japanese Patent Nos. 4205195 and 4205198, photocrosslinkable polyimides, photocrosslinkable polyamides and photocrosslinkable polyesters described in JP-T-2003-520878, JP-T-2004-529220 and JP-T-4162850, and photodimerizable compounds described in JP-A-9-118717, JP-A-10-506420, JP-A-2003-505561, WO 2010 / 150748, JP-A-2013-177561 and JP-A-2014-12823, particularly cinnamate compounds, chalcone compounds and coumarin compounds are exemplified as preferred examples. Among these, azo compounds, photocrosslinkable polyimides, photocrosslinkable polyamides, photocrosslinkable polyesters, cinnamate compounds, and chalcone compounds are preferably used.

[0135] There is no limitation on the thickness of the alignment film 124, and it is sufficient to set the thickness appropriately so as to obtain the necessary alignment function depending on the material from which the alignment film is formed. The thickness of the alignment film is preferably 0.01 to 5 μm, and more preferably 0.05 to 2 μm.

[0136] The support and the alignment film may be a temporary support that can be peeled off and removed. In the case where a temporary support is used, it is preferable to peel off and remove the temporary support after transferring the cholesteric liquid crystal layer to another laminate, because this can eliminate the adverse effect of the retardation of the temporary support on the polarization degree of transmitted light and reflected light.

[0137] The cholesteric liquid crystal layer 126 is formed on the surface (upper surface) of the alignment film 124. Note that in FIG. 7 , in order to simplify the drawing and clearly show the configuration of the cholesteric liquid crystal layer 126, the cholesteric liquid crystal layer 126 conceptually shows only two rotations (720° rotations) of the twisted orientation of the liquid crystal compound 132 in the cholesteric liquid crystal phase. That is, FIG. 7 shows only two pitches of the helical structure in the cholesteric liquid crystal phase. However, like a typical cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase, the cholesteric liquid crystal layer 126 has a helical structure in which the liquid crystal compound 132 is stacked in a helical manner along a helical axis in the thickness direction, and the helical period is one pitch, where one rotation (360° rotation) of the liquid crystal compound 132 stacked in a helical manner is one pitch, and the helically swirling liquid crystal compound 132 is stacked in a helical manner.

[0138] That is, in the present invention, a cholesteric liquid crystal phase (cholesteric liquid crystal layer) is one in which a helical structure is laminated for one pitch or more. The cholesteric liquid crystal layer exhibits reflectivity with the above-mentioned wavelength selectivity by laminating a helical structure of liquid crystal compound 132 for one pitch or more. Therefore, in the present invention, even if a layer has a helical structure in which liquid crystal compound 132 is laminated in a helical shape along a helical axis in the thickness direction, a layer with a helical period of less than one pitch is not a cholesteric liquid crystal layer.

[0139] The cholesteric liquid crystal layer 126 is formed by fixing a cholesteric liquid crystal phase. That is, the cholesteric liquid crystal layer 126 is a layer in which a liquid crystal compound 132 (liquid crystal material) is cholesterically aligned. As is well known, a cholesteric liquid layer formed by fixing a cholesteric liquid crystal phase has wavelength-selective reflectivity. As described above, the selective reflection wavelength range of the cholesteric liquid crystal layer depends on the length of one helix pitch in the thickness direction (pitch P shown in FIG. 7 ).

[0140] In the present invention, the cholesteric liquid crystal layer 126 has a region (retardation region) where the in-plane refractive index nx in the slow axis direction and the refractive index ny in the fast axis direction satisfy nx>ny. In the present invention, the cholesteric liquid crystal layer has a configuration in which the retardation in the retardation region increases from the center to the outside, and the direction of the slow axis at a point in the retardation region is perpendicular to the direction from the center toward this point.

[0141] In the present invention, the cholesteric liquid crystal layer 126 has a configuration in which, when the alignment of the liquid crystal compounds 132 is viewed from the helical axis direction, the angle formed by the molecular axes of adjacent liquid crystal compounds 132 gradually changes, as shown in FIG. 8 . In other words, when the alignment of the liquid crystal compounds 132 is viewed from the helical axis direction, the probability of existence of the liquid crystal compounds 132 differs. As a result, the cholesteric liquid crystal layer 126 has a configuration in which the in-plane refractive index nx in the slow axis direction and the refractive index ny in the fast axis direction satisfy nx > ny. In the following description, the cholesteric liquid crystal layer 126 has a configuration in which, when the alignment of the liquid crystal compounds 132 is viewed from the helical axis direction, the angle formed by the molecular axes of adjacent liquid crystal compounds 132 gradually changes, as shown in FIG. 8 , is also referred to as having an index ellipsoid.

[0142] In the cholesteric liquid crystal layer, the selective reflection center wavelength is not limited and may be appropriately set depending on the application. In the present invention, the cholesteric liquid crystal layer preferably includes at least a blue light reflective layer having a reflectance of 40% or more at a wavelength of 450 nm, a green light reflective layer having a reflectance of 40% or more at a wavelength of 530 nm, and a red light reflective layer having a reflectance of 40% or more at a wavelength of 630 nm. That is, in an optical laminate having multiple cholesteric liquid crystal layers, the selective reflection center wavelengths of the cholesteric liquid crystal layers may be different from each other. This configuration is preferable because it can exhibit high reflection characteristics over a wide wavelength range in the visible range. Note that the above reflectance is the reflectance when unpolarized light is incident on the reflective circular polarizer at each wavelength. Some image display devices have emission peaks in the wavelength ranges of blue light, green light, and red light, respectively. For example, liquid crystal display devices with backlights containing quantum dots, liquid crystal display devices with backlights equipped with LEDs emitting blue, green, and red light, organic EL display devices, micro LED display devices, etc. have emission peaks with relatively narrow full widths at half maximum in the respective wavelength ranges of blue light, green light, and red light. A narrow full width at half maximum of the emission peaks of each color is preferable because it improves color reproducibility. When used in combination with these image display devices, the reflective circular polarizer (cholesteric liquid crystal layer) preferably has a selective reflection band in the wavelength range corresponding to the emission peak of the image display device. Furthermore, the blue light-reflecting layer, green light-reflecting layer, and red light-reflecting layer, each formed by fixing a cholesteric liquid crystal phase, may have a pitch gradient layer in which the helical pitch of the cholesteric liquid crystal phase is continuously changed in the thickness direction. For example, referring to JP 2020-060627 A, etc., the green light-reflecting layer and the red light-reflecting layer can be continuously fabricated.

[0143] Furthermore, when the cholesteric liquid crystal layer (optical film including a cholesteric liquid crystal layer) of the present invention is stretched or molded, the reflection wavelength range of the reflective circular polarizer may shift to the short wavelength side. Therefore, it is preferable that the reflection wavelength range be selected in advance in consideration of this wavelength shift. For example, when an optical film including a cholesteric liquid crystal layer in which a cholesteric liquid crystal phase is fixed is used as a reflective circular polarizer, the film may be stretched by stretching, molding, etc., and the helical pitch of the cholesteric liquid crystal phase may become smaller. Therefore, it is preferable to set the helical pitch of the cholesteric liquid crystal phase to a large value in advance. Furthermore, in consideration of the short wavelength shift of the reflection wavelength range due to stretching, molding, etc., it is also preferable that the reflective circular polarizer has an infrared light-reflecting layer having a reflectance of 40% or more at a wavelength of 800 nm. Furthermore, when the stretching ratio during stretching, molding, etc. is not uniform in the plane, an appropriate reflection wavelength range may be selected at each location in the plane in accordance with the wavelength shift due to stretching. In other words, there may be regions in the plane where the reflection wavelength range differs. In addition, it is preferable to set the reflection wavelength range wider than the necessary wavelength range in advance, assuming that the stretching ratio will be different at different locations in the plane.

[0144] In the present invention, when the optical laminate has multiple cholesteric liquid crystal layers, it is preferable that the cholesteric liquid crystal layers, that is, a blue light reflecting layer, a green light reflecting layer, and a red light reflecting layer, are laminated in this order. Furthermore, when a retardation layer is provided in addition to multiple cholesteric liquid crystal layers, it is preferable that the blue light reflecting layer is disposed on the opposite side of the retardation layer that converts circularly polarized light into linearly polarized light. With this arrangement, light passes through the blue light reflecting layer, the green light reflecting layer, and the red light reflecting layer in this order. The inventors believe that in this case, the influence of the Rth of each layer is reduced, particularly at oblique incidence, and therefore the degree of polarization of the reflected light and the degree of polarization of the transmitted light can be increased.

[0145] The optical laminate of the second embodiment of the present invention is also preferably formed by alternately stacking a first cholesteric liquid crystal layer formed using a rod-shaped liquid crystal compound and a second cholesteric liquid crystal layer formed using a discotic liquid crystal compound. Preferably, the first cholesteric liquid crystal layer is a light-reflecting layer formed by fixing a cholesteric liquid crystal phase containing a rod-shaped liquid crystal compound, and the second cholesteric liquid crystal layer is a light-reflecting layer formed by fixing a cholesteric liquid crystal phase containing a discotic liquid crystal compound, with the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer being arranged alternately. This configuration is preferable because the cholesteric liquid crystal phase containing the rod-shaped liquid crystal compound has a positive Rth, while the cholesteric liquid crystal phase containing the discotic liquid crystal compound has a negative Rth, thereby canceling out each other and increasing the degree of polarization of reflected light and transmitted light even for light incident from an oblique direction. In this case, the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer may have substantially the same or different selective reflection center wavelengths. According to the inventors' investigations, in this case, it is preferable that the display device includes a blue light-reflecting layer made of a cholesteric liquid crystal phase containing a discotic liquid crystal compound, a red light-reflecting layer made of a cholesteric liquid crystal phase containing a rod-shaped liquid crystal compound, and a green light-reflecting layer made of a cholesteric liquid crystal phase containing a rod-shaped liquid crystal compound, in this order, and that the blue light-reflecting layer is disposed on the surface opposite the retardation layer that converts circularly polarized light into linearly polarized light. Furthermore, from the viewpoint of luminosity, the order of the reflective layers is preferably green, red, and blue from the display side. Furthermore, from the viewpoint of compensation, the types of liquid crystals are preferably discoid, rod, discoid, or discoid, rod, and rod from the display side. The order of the reflective layers (cholesteric liquid crystal layers) and the types of liquid crystals are merely examples and are not limited to these configurations.

[0146] The thickness of the optically functional layer (cholesteric liquid crystal layer) may be appropriately set to a thickness that provides the required light reflectance depending on the material forming the cholesteric liquid crystal layer, etc., but from the viewpoint of achieving a thin film, it is preferably 30 μm or less, and more preferably 20 μm or less.

[0147] [Method for Forming a Cholesteric Liquid Crystal Layer] A cholesteric liquid crystal layer can be formed by fixing a cholesteric liquid crystal phase in a layered form. The structure in which the cholesteric liquid crystal phase is fixed may be any structure in which the orientation of the liquid crystal compound in the cholesteric liquid crystal phase is maintained. Typically, a polymerizable liquid crystal compound is oriented in the cholesteric liquid crystal phase, and then polymerized and cured by ultraviolet irradiation, heating, or the like to form a non-fluid layer, and at the same time, a structure in which the orientation is changed to a state in which it does not change due to an external field or external force is preferred. Note that in the structure in which the cholesteric liquid crystal phase is fixed, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained; in the cholesteric liquid crystal layer, the liquid crystal compound does not need to exhibit liquid crystallinity. For example, the polymerizable liquid crystal compound may be polymerized by a curing reaction and lose its liquid crystallinity.

[0148] An example of a material used to form a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase is a liquid crystal composition containing a liquid crystal compound. The liquid crystal compound is preferably a polymerizable liquid crystal compound. The liquid crystal composition used to form the cholesteric liquid crystal layer may further contain a surfactant and a chiral agent.

[0149] The polymerizable liquid crystal compound may be a rod-shaped liquid crystal compound or a discotic liquid crystal compound. Examples of rod-shaped polymerizable liquid crystal compounds that form a cholesteric liquid crystal phase include rod-shaped nematic liquid crystal compounds. Preferred rod-shaped nematic liquid crystal compounds include azomethines, azoxy compounds, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles. Not only low-molecular-weight liquid crystal compounds but also high-molecular-weight liquid crystal compounds can be used.

[0150] A polymerizable liquid crystal compound can be obtained by introducing a polymerizable group into a liquid crystal compound. Examples of the polymerizable group include an unsaturated polymerizable group, an epoxy group, and an aziridinyl group, with an unsaturated polymerizable group being preferred, and an ethylenically unsaturated polymerizable group being more preferred. The polymerizable group can be introduced into the molecule of the liquid crystal compound by various methods. The number of polymerizable groups contained in the polymerizable liquid crystal compound is preferably 1 to 6, more preferably 1 to 3. Examples of polymerizable liquid crystal compounds are described in Makromol. Chem. , Vol. 190, p. 2255 (1989), Advanced Materials Vol. 5, p. 107 (1993), U.S. Pat. No. 4,683,327, U.S. Pat. No. 5,622,648, U.S. Pat. No. 5,770,107, WO 95 / 22586, WO 95 / 24455, WO 97 / 00600, WO 98 / 23580, WO 98 / 52905, JP-A Nos. 1-272551, 6-16616, 7-110469, 11-80081, and 2001-328973. Two or more polymerizable liquid crystal compounds may be used in combination. The use of two or more polymerizable liquid crystal compounds in combination can lower the alignment temperature.

[0151] Other examples of polymerizable liquid crystal compounds that can be used include cyclic organopolysiloxane compounds having a cholesteric phase, such as those disclosed in JP-A-57-165480. Examples of the polymeric liquid crystal compounds that can be used include polymers having mesogen groups exhibiting liquid crystallinity introduced into the main chain, side chain, or both the main chain and side chain, polymeric cholesteric liquid crystals having cholesteryl groups introduced into the side chain, liquid crystalline polymers such as those disclosed in JP-A-9-133810, and liquid crystalline polymers such as those disclosed in JP-A-11-293252.

[0152] As the discotic liquid crystal compound, for example, those described in JP-A Nos. 2007-108732 and 2010-244038 can be preferably used.

[0153] The amount of the polymerizable liquid crystal compound added in the liquid crystal composition is preferably 75 to 99.9 mass %, more preferably 80 to 99 mass %, and even more preferably 85 to 90 mass %, based on the solid content mass (mass excluding the solvent) of the liquid crystal composition.

[0154] <<Surfactant>> The liquid crystal composition used to form the cholesteric liquid crystal layer may contain a surfactant. The surfactant is preferably a compound that can function as an alignment control agent that contributes to the stable or rapid alignment of the cholesteric liquid crystal phase. Examples of the surfactant include silicone surfactants and fluorine surfactants, with fluorine surfactants being a preferred example.

[0155] Specific examples of surfactants include the compounds described in paragraphs

[0082] to

[0090] of JP-A No. 2014-119605, the compounds described in paragraphs

[0031] to

[0034] of JP-A No. 2012-203237, the compounds exemplified in paragraphs

[0092] and

[0093] of JP-A No. 2005-99248, the compounds exemplified in paragraphs

[0076] to

[0078] and paragraphs

[0082] to

[0085] of JP-A No. 2002-129162, and fluorine (meth)acrylate polymers described in paragraphs

[0018] to

[0043] of JP-A No. 2007-272185, etc. One type of surfactant may be used alone, or two or more types may be used in combination. As the fluorine-based surfactant, the compounds described in paragraphs

[0082] to

[0090] of JP-A-2014-119605 are preferred.

[0156] The amount of the surfactant added in the liquid crystal composition is preferably 0.01 to 10% by mass, more preferably 0.01 to 5% by mass, and even more preferably 0.02 to 1% by mass, based on the total mass of the liquid crystal compound.

[0157] <<Chiral Agents (Optically Active Compounds)>> Chiral agents have the function of inducing a helical structure in a cholesteric liquid crystal phase. Chiral agents can be selected according to the purpose, as the twist direction or helical periodic pitch of the induced helix varies depending on the compound. There are no limitations on the chiral agent, and known compounds (e.g., those described in "Liquid Crystal Device Handbook," Chapter 3, Section 4-3, "Chiral Agents for TN (Twisted Nematic) and STN (Super Twisted Nematic)," p. 199, edited by the 142nd Committee of the Japan Society for the Promotion of Science, 1989), isosorbide, and isomannide derivatives can be used. Chiral agents generally contain an asymmetric carbon atom, but axially asymmetric or planarly asymmetric compounds without an asymmetric carbon atom can also be used as chiral agents. Examples of axially asymmetric or planarly asymmetric compounds include binaphthyl, helicene, paracyclophane, and their derivatives. The chiral agent may have a polymerizable group. When both the chiral agent and the liquid crystal compound have a polymerizable group, a polymer having a repeating unit derived from the polymerizable liquid crystal compound and a repeating unit derived from the chiral agent can be formed by a polymerization reaction between the polymerizable chiral agent and the polymerizable liquid crystal compound.In this embodiment, the polymerizable group of the polymerizable chiral agent is preferably the same type of group as the polymerizable group of the polymerizable liquid crystal compound.Therefore, the polymerizable group of the chiral agent is also preferably an unsaturated polymerizable group, an epoxy group, or an aziridinyl group, more preferably an unsaturated polymerizable group, and even more preferably an ethylenically unsaturated polymerizable group.In addition, the chiral agent may be a liquid crystal compound.

[0158] When the chiral agent has a photoisomerizable group, it is possible to form a pattern with a desired reflection wavelength corresponding to the emission wavelength by irradiating the photoresist with actinic rays or the like through a photomask after coating and alignment. The photoisomerizable group is preferably an isomerization site of a compound exhibiting photochromic properties, an azo group, an azoxy group, or a cinnamoyl group. Specific compounds that can be used include those described in JP-A-2002-80478, JP-A-2002-80851, JP-A-2002-179668, JP-A-2002-179669, JP-A-2002-179670, JP-A-2002-179681, JP-A-2002-179682, JP-A-2002-338575, JP-A-2002-338668, JP-A-2003-313189, and JP-A-2003-313292.

[0159] The content of the chiral dopant in the liquid crystal composition is preferably 0.01 to 200 mol %, more preferably 1 to 30 mol %, based on the molar amount of the liquid crystal compound.

[0160] <<Polymerization initiator>> When the liquid crystal composition contains a polymerizable compound, it preferably contains a polymerization initiator. In an embodiment in which the polymerization reaction is caused to proceed by irradiation with ultraviolet light, the polymerization initiator used is preferably a photopolymerization initiator that can initiate the polymerization reaction by irradiation with ultraviolet light. Examples of the photopolymerization initiator include α-carbonyl compounds (described in U.S. Pat. Nos. 2,367,661 and 2,367,670), acyloin ethers (described in U.S. Pat. No. 2,448,828), α-hydrocarbon-substituted aromatic acyloin compounds (described in U.S. Pat. No. 2,722,512), polynuclear quinone compounds (described in U.S. Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketones (described in U.S. Pat. No. 3,549,367), acridine and phenazine compounds (described in JP-A No. 60-105667 and U.S. Pat. No. 4,239,850), and oxadiazole compounds (described in U.S. Pat. No. 4,212,970).

[0161] Among these, the polymerization initiator is preferably a dichroic radical polymerization initiator. A dichroic radical polymerization initiator is a photopolymerization initiator that has absorption selectivity for light of a specific polarization direction and generates free radicals upon excitation by the polarization. In other words, a dichroic radical polymerization initiator is a polymerization initiator that has different absorption selectivity for light of a specific polarization direction and light of a polarization direction perpendicular to the specific polarization direction. Details and specific examples are described in WO 2003 / 054111. Specific examples of dichroic radical polymerization initiators include polymerization initiators of the following chemical formula. Furthermore, as dichroic radical polymerization initiators, the polymerization initiators described in paragraphs

[0046] to

[0097] of JP-A No. 2016-535863 can be used.

[0162]

[0163] The content of the photopolymerization initiator in the liquid crystal composition is preferably 0.1 to 20% by mass, more preferably 0.5 to 12% by mass, based on the content of the liquid crystal compound.

[0164] <<Crosslinking Agent>> The liquid crystal composition may optionally contain a crosslinking agent in order to improve the film strength and durability after curing. As the crosslinking agent, one that cures by ultraviolet light, heat, moisture, etc. can be suitably used. The crosslinking agent is not particularly limited and can be appropriately selected depending on the purpose. Examples include polyfunctional acrylate compounds such as trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate; epoxy compounds such as glycidyl (meth)acrylate and ethylene glycol diglycidyl ether; aziridine compounds such as 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate] and 4,4-bis(ethyleneiminocarbonylamino)diphenylmethane; isocyanate compounds such as hexamethylene diisocyanate and biuret-type isocyanate; polyoxazoline compounds having an oxazoline group in the side chain; and alkoxysilane compounds such as vinyltrimethoxysilane and N-(2-aminoethyl)3-aminopropyltrimethoxysilane. Furthermore, known catalysts can be used depending on the reactivity of the crosslinking agent, which can improve productivity in addition to improving film strength and durability. These may be used alone or in combination of two or more. The content of the crosslinking agent is preferably 3 to 20% by mass, more preferably 5 to 15% by mass, based on the mass of the solid content of the liquid crystal composition. When the content of the crosslinking agent is within the above range, the effect of improving the crosslink density is easily obtained, and the stability of the cholesteric liquid crystal phase is further improved.

[0165] <<Other Additives>> If necessary, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, a colorant, metal oxide fine particles, and the like may be further added to the liquid crystal composition within a range that does not impair optical performance, etc.

[0166] The liquid crystal composition is preferably used as a liquid when forming a cholesteric liquid crystal layer. The liquid crystal composition may contain a solvent. The solvent is not limited and can be appropriately selected depending on the purpose, but organic solvents are preferred. The organic solvent is not limited and can be appropriately selected depending on the purpose, and examples thereof include ketones, alkyl halides, amides, sulfoxides, heterocyclic compounds, hydrocarbons, esters, and ethers. These may be used alone or in combination of two or more. Among these, ketones are preferred when considering the environmental impact.

[0167] When forming a cholesteric liquid crystal layer, it is preferable to apply a liquid crystal composition to the surface on which the cholesteric liquid crystal layer is to be formed, align the liquid crystal compound in a cholesteric liquid crystal phase, and then harden the liquid crystal compound to form a cholesteric liquid crystal layer. For example, when forming a cholesteric liquid crystal layer 126 on an alignment film 124, it is preferable to apply a liquid crystal composition to the alignment film 124, align the liquid crystal compound in a cholesteric liquid crystal phase, and then harden the liquid crystal compound to fix the cholesteric liquid crystal phase to form a cholesteric liquid crystal layer 126. The liquid crystal composition can be applied by any known method that can uniformly apply a liquid to a sheet-like material, such as printing methods such as inkjet printing and scroll printing, as well as spin coating, bar coating, and spray coating.

[0168] The applied liquid crystal composition is dried and / or heated as necessary, and then cured to form a cholesteric liquid crystal layer. During this drying and / or heating process, the liquid crystal compounds in the liquid crystal composition may be oriented in a cholesteric liquid crystal phase. When heating is performed, the heating temperature is preferably 200° C. or lower, and more preferably 130° C. or lower.

[0169] The aligned liquid crystal compound is further polymerized as needed. The polymerization may be either thermal polymerization or photopolymerization by light irradiation, but photopolymerization is preferred. The light irradiation is preferably ultraviolet light. The irradiation energy is 20 mJ / cm. 2 ~50 J / cm 2 is preferred, and 50 to 1500 mJ / cm 2In order to promote the photopolymerization reaction, the light may be emitted under heated conditions or in a nitrogen atmosphere. The wavelength of the emitted ultraviolet light is preferably 250 to 430 nm.

[0170] (Liquid Crystal Elastomer) In the present invention, a liquid crystal elastomer may be used in the cholesteric liquid crystal layer. Liquid crystal elastomers are hybrid materials of liquid crystals and elastomers. For example, they have a structure in which rigid mesogen groups with liquid crystal properties are introduced into a flexible polymer network with rubber elasticity. Therefore, they have flexible mechanical properties and are stretchable. Furthermore, because the orientation state of the liquid crystals and the macroscopic shape of the system are strongly correlated, changes in the orientation state of the liquid crystals due to temperature, electric field, etc., result in macroscopic deformation in response to changes in the orientation degree. For example, when a liquid crystal elastomer is heated from the nematic phase to a temperature at which it becomes an isotropic phase with random orientation, the sample shrinks in one direction along the director, and the amount of shrinkage increases with increasing temperature, i.e., with a decrease in the orientation degree of the liquid crystals. The deformation is thermoreversible, and the original shape is restored when the temperature is lowered back to the nematic phase. On the other hand, when the liquid crystal elastomer in the cholesteric liquid crystal phase is heated and the degree of liquid crystal orientation decreases, macroscopic elongation deformation occurs in the direction of the helical axis, increasing the helical pitch length and shifting the central reflection wavelength of the selective reflection peak to the longer wavelength side. This change is also thermoreversible, and the central reflection wavelength returns to the shorter wavelength side as the temperature decreases.

[0171] <<Index Ellipsoid of Cholesteric Liquid Crystal Layer>> As described above, the cholesteric liquid crystal layer 126 has an index ellipsoid in which, when the alignment of the liquid crystal compounds 132 is viewed from the helical axis direction, the angle formed by the molecular axes of adjacent liquid crystal compounds 132 gradually changes. The index ellipsoid will be described with reference to FIGS. 9 and 10 . FIG. 9 is a diagram showing a portion (1 / 4 pitch) of multiple liquid crystal compounds helically aligned along the helical axis, viewed from the helical axis direction (z direction), and FIG. 10 is a diagram conceptually showing the existence probability of liquid crystal compounds as viewed from the helical axis direction. In FIG. 9 , the liquid crystal compound is a rod-shaped liquid crystal compound, and the long axis of the rod-shaped liquid crystal compound is the molecular axis. In the case where the liquid crystal compound is a discotic liquid crystal compound, the discotic plane direction of the discotic liquid crystal compound as viewed from the helical axis direction is the molecular axis.

[0172] In Figure 9, the liquid crystal compound whose molecular axis is parallel to the y direction is designated C1, the liquid crystal compound whose molecular axis is parallel to the x direction is designated C7, and the liquid crystal compounds between C1 and C7 are designated C2 to C6 from the liquid crystal compound C1 side to the liquid crystal compound C7 side. Liquid crystal compounds C1 to C7 are twisted along their helical axes, rotating 90° between liquid crystal compounds C1 and C7. If the length between the liquid crystal compounds over which the twisted angle of the twisted liquid crystal compounds changes by 360° is designated as one pitch ("P" in Figure 7), then the length in the helical axis direction from liquid crystal compound C1 to liquid crystal compound C7 (the direction perpendicular to the paper surface of Figure 9) is 1 / 4 pitch.

[0173] 9, the angles formed by the molecular axes of adjacent liquid crystal compounds, as viewed from the z direction (the helix axis direction), are different within a quarter-pitch from liquid crystal compound C1 to liquid crystal compound C7. In the example shown in Fig. 9, the angle θ1 between liquid crystal compound C1 and liquid crystal compound C2 is larger than the angle θ2 between liquid crystal compound C2 and liquid crystal compound C3, the angle θ2 between liquid crystal compound C2 and liquid crystal compound C3 is larger than the angle θ3 between liquid crystal compound C3 and liquid crystal compound C4, the angle θ3 between liquid crystal compound C3 and liquid crystal compound C4 is larger than the angle θ4 between liquid crystal compound C4 and liquid crystal compound C5, the angle θ4 between liquid crystal compound C4 and liquid crystal compound C5 is larger than the angle θ5 between liquid crystal compound C5 and liquid crystal compound C6, the angle θ5 between liquid crystal compound C5 and liquid crystal compound C6 is larger than the angle θ6 between liquid crystal compound C6 and liquid crystal compound C7, and the angle θ6 between liquid crystal compound C6 and liquid crystal compound C7 is smallest.

[0174] That is, the liquid crystal compounds C1 to C7 are twistedly aligned such that the angle between the molecular axes of adjacent liquid crystal compounds decreases from the liquid crystal compound C1 side toward the liquid crystal compound C7 side. For example, if the spacing (spacing in the thickness direction) between the liquid crystal compounds is approximately constant, the rotation angle per unit length decreases from the liquid crystal compound C1 side toward the liquid crystal compound C7 side within a quarter pitch from the liquid crystal compound C1 to the liquid crystal compound C7. In the cholesteric liquid crystal layer 126, this configuration in which the rotation angle per unit length changes within a quarter pitch is repeated, resulting in twisted alignment of the liquid crystal compounds.

[0175] Here, when the rotation angle per unit length is constant, the angle between the molecular axes of adjacent liquid crystal compounds is constant, so the probability of existence of the liquid crystal compound as viewed from the helical axis direction is the same in any direction. Therefore, in this case, the cholesteric liquid crystal layer does not have refractive index anisotropy (is isotropic) in the in-plane direction. In contrast, as described above, by configuring the rotation angle per unit length to decrease from the liquid crystal compound C1 side toward the liquid crystal compound C7 side within the 1 / 4 pitch from liquid crystal compound C1 to liquid crystal compound C7, the probability of existence of the liquid crystal compound as viewed from the helical axis direction is higher in the x direction than in the y direction, as conceptually shown in FIG. 10 . Since the probability of existence of the liquid crystal compound differs between the x direction and the y direction, the refractive index differs between the x direction and the y direction, resulting in refractive index anisotropy. In other words, refractive index anisotropy occurs in the plane perpendicular to the helical axis.

[0176] The refractive index nx in the x direction, where the probability of existence of liquid crystal compounds is high, is higher than the refractive index ny in the y direction, where the probability of existence of liquid crystal compounds is low. Therefore, the refractive indexes nx and ny satisfy the relationship nx > ny. The x direction, where the probability of existence of liquid crystal compounds is high, corresponds to the slow axis direction in the plane of the cholesteric liquid crystal layer 126, and the y direction, where the probability of existence of liquid crystal compounds is low, corresponds to the fast axis direction in the plane of the cholesteric liquid crystal layer 126.

[0177] In this way, a configuration in which the rotation angle per unit length changes within a quarter pitch in the twisted orientation of a liquid crystal compound (a configuration having an index ellipsoid) can be formed by applying a composition that will become a cholesteric liquid crystal layer and then irradiating the cholesteric liquid crystal phase (composition layer) with polarized light in a direction perpendicular to the helical axis.

[0178] Polarized light irradiation can distort the cholesteric liquid crystal phase to generate in-plane retardation, i.e., the refractive index nx can be made greater than the refractive index ny.

[0179] Specifically, polymerization of liquid crystal compounds having molecular axes aligned with the polarization direction of the irradiated polarized light proceeds. Since only a portion of the liquid crystal compounds polymerizes, the chiral agent present at this location is eliminated and migrates to other locations. Therefore, at locations where the direction of the molecular axes of the liquid crystal compounds is close to the polarization direction, the amount of chiral agent decreases, resulting in a smaller rotation angle of the twisted alignment. On the other hand, at locations where the direction of the molecular axes of the liquid crystal compounds is perpendicular to the polarization direction, the amount of chiral agent increases, resulting in a larger rotation angle of the twisted alignment. As a result, as shown in FIG. 9 , in liquid crystal compounds twisted along the helical axis, within a quarter-pitch from the liquid crystal compound whose molecular axis is parallel to the polarization direction to the liquid crystal compound whose axis is perpendicular to the polarization direction, the angle between the molecular axes of adjacent liquid crystal compounds decreases as one moves from the liquid crystal compound parallel to the polarization direction toward the liquid crystal compound whose axis is perpendicular to the polarization direction. In other words, by irradiating polarized light to a cholesteric liquid crystal phase, the probability of existence of liquid crystal compounds differs between the x and y directions, resulting in refractive index anisotropy, where the refractive index differs between the x and y directions. This allows the refractive index nx and the refractive index ny of the optical element 10 to satisfy nx>ny, that is, the cholesteric liquid crystal layer can have an index ellipsoid.

[0180] This polarized light irradiation may be carried out simultaneously with the fixation of the cholesteric liquid crystal phase, or polarized light irradiation may be carried out first and then non-polarized light irradiation may be carried out for further fixation, or non-polarized light irradiation may be carried out first and then photo-alignment may be carried out by polarized light irradiation. To obtain a large retardation, it is preferable to carry out polarized light irradiation alone or to carry out polarized light irradiation first. Polarized light irradiation is preferably carried out in an inert gas atmosphere with an oxygen concentration of 0.5% or less. The irradiation energy is 20 mJ / cm 2 ~10 J / cm 2 is preferably 100 to 800 mJ / cm 2 It is more preferable that the illuminance is 20 to 1000 mW / cm. 2 is preferably 50 to 500 mW / cm 2 More preferably, it is 100 to 350 mW / cm 2The type of liquid crystal compound that is cured by irradiation with polarized light is not particularly limited, but a liquid crystal compound having an ethylenically unsaturated group as a reactive group is preferred.

[0181] In addition, examples of a method for distorting a cholesteric liquid crystal phase by irradiating it with polarized light to generate in-plane retardation include a method using a dichroic liquid crystal polymerization initiator (WO 03 / 054111 A1) and a method using a rod-shaped liquid crystal compound having a photoalignable functional group such as a cinnamoyl group in the molecule (JP 2002-6138 A).

[0182] The light to be irradiated may be ultraviolet light, visible light, or infrared light. That is, light that can polymerize the liquid crystal compound may be appropriately selected depending on the liquid crystal compound and polymerization initiator contained in the coating film.

[0183] By using a dichroic radical polymerization initiator as the polymerization initiator, when the composition layer is irradiated with polarized light, the polymerization of the liquid crystal compound having a molecular axis in a direction that matches the polarization direction can be more suitably promoted.

[0184] The in-plane slow axis direction, fast axis direction, refractive index nx, and refractive index ny can be measured using a spectroscopic ellipsometer M-2000UI manufactured by J. A. Woollam Co. Inc. The refractive index nx and refractive index ny can be calculated from the average birefringence n ave and the measured value of the thickness d. Here, Δn=nx-ny, the average refractive index n ave = (nx + ny) / 2. Generally, the average refractive index of liquid crystal is about 1.5, so nx and ny can also be calculated using this value. Furthermore, when measuring the in-plane slow axis direction, fast axis direction, refractive index nx, and refractive index ny of the cholesteric liquid crystal layer used in the present invention, the measurement wavelength is a wavelength obtained by subtracting 20 nm from the half-value wavelength on the side shorter than the selective reflection center wavelength in the cholesteric liquid crystal layer. In this way, the influence of the optical rotation component of the retardation resulting from cholesteric selective reflection can be minimized, allowing for accurate measurements.

[0185] Furthermore, a cholesteric liquid crystal layer having an index ellipsoid can also be formed by stretching a cholesteric liquid crystal layer after applying a composition that will become the cholesteric liquid crystal layer, or after fixing the cholesteric liquid crystal phase, or while the cholesteric liquid crystal phase is semi-fixed.

[0186] In the second embodiment of the present invention, the slow axis of the cholesteric liquid crystal layer having an index ellipsoid preferably has multiple in-plane orientations, and the orientation is preferably changed depending on the application. For example, when molding onto a curved surface such as a part of a sphere, it is preferable to arrange the slow axis substantially concentrically, since this can cancel out the phase difference caused by stretching during molding. Furthermore, it is preferable that the retardation after molding is less than 10 nm.

[0187] Specifically, the cholesteric liquid crystal layer has a retardation region in which the retardation increases from the center to the outside, and in the retardation region, the direction of the slow axis at a point in the retardation region is perpendicular to the direction from the center to the point. A cholesteric liquid crystal layer having such a configuration will be described with reference to FIG.

[0188] 12 is a diagram conceptually showing the slow axis of the cholesteric liquid crystal layer of the present invention. In FIG. 12, the direction of the slow axis in a minute region in the plane of the cholesteric liquid crystal layer is indicated by an arrow, and the magnitude of the retardation in that region is indicated by the length of the arrow. In FIG. 12, the retardation is approximately 0 at the center O. Also, for example, the retardation is approximately 0 at the center O. １ On the line indicated by , the directions of the slow axes at the positions (microscopic regions) of points P1, P2, and P3 are all substantially perpendicular to the dashed-dotted line r1. The magnitude of the phase difference at point P2 is larger than the phase difference at point P1, and the magnitude of the phase difference at point P3 is larger than the phase difference at point P2. In other words, the phase difference increases as the position moves further outward from the center O.

[0189] 12 , in the cholesteric liquid crystal layer, the retardation increases from the center O toward the outside in any direction from the center O toward the outside, and the direction of the slow axis at a certain point is approximately perpendicular to the line connecting this point and the center O. In other words, the direction of the slow axis is approximately perpendicular to the radial direction. Thus, in the cholesteric liquid crystal layer, the direction of the slow axis and the magnitude of the retardation for each minute region in the plane vary depending on the position in the plane.

[0190] Preferably, as shown in FIG. 12, the magnitude of the phase difference is approximately the same at positions that are the same distance from the center O.

[0191] In the cholesteric liquid crystal layer shown in Fig. 12, if a tangent line is drawn that touches all the arrows representing the slow axes in the regions with the same magnitude of retardation, a circle with a center O is drawn, as shown by the dashed line in Fig. 12. Circles with different diameters are drawn for each magnitude of retardation, and multiple circles become concentric circles that share the center O. In the following description, the slow axis pattern shown in Fig. 12 is also referred to as a concentric pattern.

[0192] The cholesteric liquid crystal layer of the second embodiment of the present invention has a concentric pattern of slow axes, and therefore, when the cholesteric liquid crystal layer is molded into a curved surface such as a part of a sphere, the phase difference caused by stretching during molding can be canceled out.

[0193] Specifically, in the case of a conventional cholesteric liquid crystal layer, the angle between the molecular axes of adjacent liquid crystal compounds as viewed from the helical axis direction is approximately constant, i.e., the rotation angle per unit length is constant. Therefore, a conventional cholesteric liquid crystal layer is isotropic, i.e., has no refractive index anisotropy (phase difference) at any position (microscopic region) in the plane.

[0194] When such a conventional cholesteric liquid crystal layer is molded onto a curved surface, such as a portion of a sphere, the region near the center is stretched at a constant stretch ratio regardless of the direction in a planar view, so no anisotropy occurs. However, regions near the edges of the molded region are stretched at different stretch ratios in the circumferential and radial directions. This results in a bias in the probability of liquid crystal compounds existing in the circumferential and radial directions, which in turn results in refractive index anisotropy (phase difference). Specifically, the stretch ratio in the circumferential direction is smaller and the stretch ratio in the radial direction is higher in regions closer to the edges, resulting in a higher probability of liquid crystal compounds existing in the radial direction and a slow axis in the radial direction (see Figure 6). Thus, when a conventional cholesteric liquid crystal layer is molded onto a curved surface, such as a portion of a sphere, the magnitude of the resulting phase difference varies depending on the in-plane position. Therefore, when the molded cholesteric liquid crystal layer is used as a reflective circular polarizer that constitutes a pancake lens in a virtual reality display device, it is unable to properly reflect and transmit incident light, resulting in increased light leakage. In a virtual reality display device, the leaking light is perceived as a ghost.

[0195] In contrast, the cholesteric liquid crystal layer of the second embodiment of the present invention has a concentric pattern in which the retardation increases toward the outside and the direction of the slow axis is approximately perpendicular to the radial direction. Therefore, for example, when molded into a curved surface such as a part of a sphere, the region near the center is stretched at a constant stretching ratio regardless of the direction in a planar view, so no anisotropy occurs and the retardation remains approximately zero. On the other hand, the region near the edge of the molded region is stretched at a small stretching ratio in the circumferential direction and a high stretching ratio in the radial direction. However, since the direction of the slow axis in the region near the edge is approximately perpendicular to the radial direction, i.e., the probability of liquid crystal compounds existing in the direction approximately perpendicular to the radial direction (circumferential direction) is high, stretching in the radial direction reduces the difference in the probability of liquid crystal compounds existing in the radial direction and the circumferential direction. This reduces the anisotropy of the refractive index (retardation) in the region near the edge. In this way, by imparting a concentric pattern to the cholesteric liquid crystal layer, in which the retardation increases toward the outside and the direction of the slow axis is approximately perpendicular to the radial direction, depending on the circumferential stretching ratio and radial stretching ratio at each position during molding, the retardation can be reduced (to approximately 0) in each region within the plane after molding. Therefore, when the cholesteric liquid crystal layer of the present invention is molded and used as a reflective circular polarizer that constitutes a pancake lens in a virtual reality display device, incident light can be appropriately reflected and transmitted, reducing light leakage. This can suppress the visibility of ghosts in the virtual reality display device.

[0196] A method for forming a cholesteric liquid crystal layer having a concentric pattern in which the retardation increases toward the outside and the direction of the slow axis is approximately perpendicular to the radial direction will be described. As described above, a cholesteric liquid crystal layer having a retardation can be formed by applying a composition that will become the cholesteric liquid crystal layer and then irradiating the cholesteric liquid crystal phase (composition layer) with polarized light. In this case, the probability of the presence of liquid crystal compounds increases in the direction of the polarized light, and an index ellipsoid is formed in which the slow axis direction is the direction of the polarized light. Therefore, the polarized light can be irradiated so that the retardation increases toward the outside and the direction of the slow axis is approximately perpendicular to the radial direction, resulting in a concentric pattern.

[0197] In order to allow the slow axis of the cholesteric liquid crystal layer having an index ellipsoid to have multiple in-plane orientations, a known polarized light exposure method can be used, as specifically described in JP-A-2008-233903.

[0198] One example is a method of irradiating polarized light while rotating a cholesteric liquid crystal phase (composition layer) using a mask as shown in Figure 11. The mask shown in Figure 11 has triangular transmission portions whose apexes are approximately aligned with the center and which are elongated toward the edges. Furthermore, the light transmittance (transmittance of light of the wavelength used for exposure) in the transmission portions is low toward the center and high toward the edges. By irradiating the cholesteric liquid crystal phase (composition layer) with polarized light in a direction perpendicular to the radial direction through this mask and rotating the cholesteric liquid crystal phase (composition layer) around the apex of the triangular transmission portion, a concentric pattern can be formed in which the phase difference is larger toward the outside and the direction of the slow axis is approximately perpendicular to the radial direction.

[0199] <Optical Laminate> The optical laminate of the second embodiment of the present invention includes, for example, the above-mentioned optical functional layer (cholesteric liquid crystal layer) and a substrate film. The optical functional layer may also be formed by laminating multiple layers. Examples of the substrate film include polyacrylate and polymethacrylate.

[0200] <Optical Component> The optical component of the second embodiment of the present invention is a molded body (curved optically functional layer) obtained by molding the above-mentioned cholesteric liquid crystal layer. When the optical component is used in a pancake lens type virtual reality display device, the optical component can be designed to have an appropriate shape with a curved surface so as to obtain a wide field of view, low chromatic aberration, low distortion, and excellent MTF.

[0201] The molded body can have various shapes, such as a partial sphere, a parabolic solid of revolution, or an aspherical lens shape. The shape of the molded body may also be a shape that matches the shape of the lens to be laminated. Specifically, a molded body obtained by molding the cholesteric liquid crystal layer (or optical laminate including the layer) of the second embodiment of the present invention can have a configuration similar to that of the first aspect of the optical film of the first embodiment of the present invention. That is, the molded body has a curved surface shape with a non-developable surface having a positive Gaussian curvature. Examples of such curved surface shapes include a spherical surface, a parabolic surface, an ellipsoidal surface, an aspherical surface whose curvature changes from the center outward, and a curved surface asymmetric with respect to the center, such as a curved surface asymmetric with respect to the optical axis in the diameter direction of a circular lens. Furthermore, in molded bodies having such curved surface shapes, there are no limitations on the peripheral shape (shape of the peripheral edge), i.e., the planar shape. Various shapes, such as an ellipse, an oval other than an ellipse, a polygon, and an irregular shape, can be used. Among these, an ellipse is preferred. In the present invention, the term "oval" includes a circle. The planar shape refers to the shape when viewed from the normal direction of the top (bottom) of the curved surface of the molded body, and for example, when the molded body having a curved shape is a lens, it is usually the shape when viewed from the optical axis direction.

[0202] The molded body obtained by molding the cholesteric liquid crystal layer (or optical laminate including the same) of the second embodiment of the present invention can be such that, similarly to the first aspect of the optical film of the first embodiment, the evaluation wavelength (measurement wavelength) is a wavelength obtained by subtracting 20 nm from the half-value wavelength on the side shorter than the selective reflection center wavelength in the cholesteric liquid crystal layer, the in-plane retardation A at the evaluation wavelength at the center is less than 2% of the evaluation wavelength, and the in-plane retardation B at the evaluation wavelength at the outer edge is less than 2% of the evaluation wavelength.

[0203] The method for producing such a molded article (curved optically functional layer) includes a cholesteric liquid crystal layer preparation step for preparing the above-mentioned cholesteric liquid crystal layer, and a molding step for molding the cholesteric liquid crystal layer into a curved shape so as to eliminate the retardation of the cholesteric liquid crystal layer. In the molding step, it is preferable to place the cholesteric liquid crystal layer on a mold having a concave molding surface so that the bottom of the concave molding surface of the mold coincides with the center of the cholesteric liquid crystal layer (the center of the retardation region), and deform the cholesteric liquid crystal layer to conform to the concave molding surface. Conventional molding methods such as vacuum molding can be used as molding methods using a mold having such a concave molding surface.

[0204] <Virtual Reality Display Device> A virtual reality display device according to a second embodiment of the present invention includes at least an image display device that emits polarized light and the optical component (molded body) according to the second embodiment of the present invention. The device may also include additional optical components such as a half mirror and a diopter adjustment lens. Known image display devices can be used as the image display device that emits polarized light. Examples include organic electroluminescence (EL) display devices, LED (Light Emitting Diode) display devices, and micro-LED display devices, which are self-luminous display devices with minute light emitters arranged on a transparent substrate. These self-luminous display devices typically have a (circular) polarizing plate attached to the display surface to prevent reflection. Therefore, the emitted light is polarized. Another example of an image display device is a liquid crystal display device. Liquid crystal display devices also have a polarizing plate on their surface, so the emitted light is polarized. In the following description, an organic electroluminescence display device is also referred to as an OLED. OLED stands for "organic light-emitting diode."

[0205] Specifically, the virtual reality display device of the second embodiment of the present invention can be configured in the same manner as the virtual reality display device of the first embodiment, except that in the virtual reality display device shown in Figure 1, a molded body formed from the cholesteric liquid crystal layer (optical laminate including the same) of the second embodiment of the present invention is used as the optical laminate 100.

[0206] The features of the present invention will be explained in more detail below with reference to examples. Note that the materials, amounts used, ratios, processing details, processing procedures, etc. shown below can be changed as appropriate without departing from the spirit of the present invention. Furthermore, configurations other than those shown below can also be used without departing from the spirit of the present invention.

[0207] [Example of First Embodiment] [Preparation of Reflective Layer Coating Liquids R-1 to R-6]

[0208] The compositions shown below were stirred and dissolved in a container kept at 70°C to prepare coating solutions R-1 to R-6 for the reflective layer, respectively. Here, R represents a coating solution using rod-like liquid crystals.

[0209] -------------------------------------------------- Coating liquid for reflective layer (containing rod-shaped liquid crystal compound) -------------------------------------------------- Methyl ethyl ketone 120.9 parts by mass Cyclohexanone 21.3 parts by mass Mixture of the following rod-shaped liquid crystal compounds 100.0 parts by mass Photopolymerization initiator B 1.00 part by mass Chiral agent A listed in Table 1 below Surfactant F1 listed below 0.027 parts by mass Surfactant F2 listed below 0.067 parts by mass

[0210] Amount of chiral agent in coating liquid (R-1 to R6) containing rod-shaped liquid crystal compound

[0211] A mixture of rod-shaped liquid crystal compounds In the above mixture, the numerical values ​​are in mass %. R is a group bonded via an oxygen atom. Furthermore, the average molar absorption coefficient of the above rod-shaped liquid crystal in the wavelength range of 300 to 400 nm was 140 / mol cm.

[0212] Chiral agent A

[0213] Surfactant F1

[0214] Surfactant F2

[0215] Photopolymerization initiator B

[0216] The chiral agent A is a chiral agent whose helical twisting power (HTP) is reduced by light.

[0217] (Reflective layer coating solutions D-1 to D-7) The compositions shown below were stirred and dissolved in a container kept at 50° C. to prepare reflective layer coating solutions D-1 to D-7, where D represents a coating solution using a discotic liquid crystal.

[0218] -------------------------------- Coating liquid for reflective layer (containing discotic liquid crystal compound) -------------------------------------------------- 80 parts by mass of the following discotic liquid crystal compound (A) 20 parts by mass of the following discotic liquid crystal compound (B) Polymerizable monomer E1 10 parts by mass Surfactant F4 0.3 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by BASF) 3 parts by mass Chiral agent A shown in Table 2 below Methyl ethyl ketone 290 parts by mass Cyclohexanone 50 parts by mass ------------------------------------------------

[0219] Amount of chiral agent in coating solution containing discotic liquid crystal compound

[0220] Discotic Liquid Crystal Compound (A)

[0221] Discotic Liquid Crystal Compound (B)

[0222] Polymerizable Monomer E1

[0223] Surfactant F4

[0224] [Preparation of Optical Film 1] A 50 μm thick PET (polyethylene terephthalate) film (A4100, manufactured by Toyobo Co., Ltd.) was prepared as a temporary support. This PET film had an easy-adhesion layer on one surface.

[0225] The surface of the PET film described above that did not have an easy-adhesion layer was subjected to a rubbing treatment, and the reflective layer coating solution R-1 prepared above was applied using a wire bar coater. The coating was then dried at 110°C for 120 seconds, and after the solvent was evaporated, heat aging was carried out at 100°C for 1 minute to obtain a uniform alignment state. Thereafter, the coating was irradiated with an exposure dose of 5 mJ / cm2 through an exposure mask at 40°C under atmospheric conditions. 2 The photoisomerization was carried out by irradiating the film with light from a high-pressure mercury lamp. An image of the exposure mask used is shown in Figure 5. A rotationally symmetric exposure mask was used, with high transmittance at the center and decreasing transmittance toward the edges. After that, the film was exposed to light at an illuminance of 80 mW / cm at 100°C in a low-oxygen atmosphere (100 ppm or less). 2 , irradiation amount 500mJ / cm 2 The red light-reflecting layer was formed from a cholesteric liquid crystal layer by curing the layer with light from a metal halide lamp. The light irradiation was performed from the cholesteric liquid crystal layer side in all cases. The coating thickness was adjusted so that the cured red light-reflecting layer would have a thickness of 4.5 μm. Photoisomerization using an exposure mask produced a patterned cholesteric liquid crystal layer with an in-plane distribution of the helical pitch of the cholesteric liquid crystal, with a central wavelength of 701 nm in the center reflection spectrum and a central wavelength of 683 nm in the edge reflection spectrum.

[0226] Next, the red light reflecting layer surface was subjected to a discharge of 150 W·min / m 2 After corona treatment at 40°C, the reflective layer coating solution D-2 was applied onto the corona-treated surface using a wire bar coater. The coating film was then dried at 70°C for 2 minutes, and after the solvent was evaporated, it was heat-aged at 115°C for 3 minutes to obtain a uniform alignment state. Then, the coating film was exposed to light at an exposure dose of 5 mJ / cm2 through an exposure mask at 40°C in the atmosphere. 2The film was irradiated with light from a high-pressure mercury lamp to cause photoisomerization. The exposure mask used here was the same as that used for the first red light reflective layer. After that, the film was again heated and aged at 115°C for 3 minutes to obtain a uniformly oriented state, and then aged at 100°C in a low-oxygen atmosphere (100 ppm or less) with an illuminance of 80 mW / cm. 2 , irradiation amount 500mJ / cm 2 The coating was cured by irradiating it with light from a metal halide lamp at 1000 kJ / cm2, thereby forming a yellow light reflective layer on the red light reflective layer. The light irradiation was carried out from the cholesteric liquid crystal layer side in all cases. The coating thickness was adjusted so that the film thickness of the cured yellow light reflective layer would be 3.3 μm.

[0227] Next, the reflective layer coating solution R-3 was applied onto the yellow light reflective layer using a wire bar coater, and then dried at 110°C for 120 seconds. After evaporating the solvent, the layer was heated and aged at 100°C for 1 minute to obtain a uniform alignment state. Thereafter, the layer was irradiated with light from a high-pressure mercury lamp at an exposure dose of 5 mJ / cm2 through an exposure mask in the atmosphere at 40°C to perform photoisomerization. The exposure mask used here was the same as the exposure mask used for the first red light reflective layer. Then, the layer was irradiated with light from a high-pressure mercury lamp at an exposure dose of 5 mJ / cm2 through an exposure mask in a low-oxygen atmosphere (100 ppm or less) at 100°C with an illuminance of 80 mW / cm2. 2 , irradiation amount 500mJ / cm 2 The coating was cured by irradiating it with light from a metal halide lamp at 1000 kJ / cm2, thereby forming a green light reflective layer on the yellow light reflective layer. The light irradiation was carried out from the cholesteric liquid crystal layer side in all cases. The coating thickness was adjusted so that the film thickness of the cured green light reflective layer would be 2.7 μm.

[0228] Next, the red light reflecting layer surface was subjected to a discharge of 150 W·min / m 2 After corona treatment at 40°C, the reflective layer coating solution D-4 was applied onto the corona-treated surface using a wire bar coater. The coating film was then dried at 70°C for 2 minutes, and after the solvent was evaporated, it was heat-aged at 115°C for 3 minutes to obtain a uniform alignment state. Then, the coating film was exposed to light at an exposure dose of 5 mJ / cm2 through an exposure mask at 40°C in the atmosphere. 2The film was irradiated with light from a high-pressure mercury lamp to cause photoisomerization. The exposure mask used here was the same as that used for the first red light reflective layer. After that, the film was again heated and aged at 115°C for 3 minutes to obtain a uniformly oriented state, and then aged in a low-oxygen atmosphere (100 ppm or less) at 100°C with an illuminance of 80 mW / cm2 and an exposure dose of 500 mJ / cm2. ２ The coating was cured by irradiating it with light from a metal halide lamp (1000 W / m²). A blue light reflective layer was formed on the green light reflective layer. The light irradiation was carried out from the cholesteric liquid crystal layer side. The coating thickness was adjusted so that the film thickness of the blue light reflective layer after curing was 2.5 μm. Optical film 1 was thus produced.

[0229] The coating solution for the reflective layer, the amount of chiral agent, the reflection center wavelength, and the film thickness used in the preparation of Optical Film 1 are shown in the table below. Here, the reflection center wavelength is used to define the characteristics of a light-reflective film having a reflection band using a cholesteric liquid crystal phase, and refers to the midpoint of the spectral band reflected by the film. Specifically, it was obtained by calculating the average value of the wavelengths on the short wavelength side and the long wavelength side that show half-value of the peak reflectance. The reflection center wavelength (the central wavelength of the reflected light) was confirmed by preparing a film coated with only a single layer. The film thickness was confirmed using an SEM.

[0230] Reflective layer (cholesteric liquid crystal layer) of optical film 1

[0231] [Preparation of Optical Film 2] Optical film 2 was prepared using the same method as reflective circular polarizer 1, except that the number of layers was increased to 8 and the coating liquid for the reflective layer, the amount of chiral agent, the reflection center wavelength, and the film thickness were changed as shown in the table below.

[0232] Reflective layer (cholesteric liquid crystal layer) of optical film 2

[0233] [Preparation of Optical Films 3 and 4] Optical film 3 was prepared in the process of preparing optical film 1, without carrying out the isomerization exposure using an exposure mask when preparing the reflective layer (cholesteric liquid crystal layer).

[0234] Optical film 4 was produced in the process of producing optical film 2, without carrying out the isomerization exposure using an exposure mask when producing the reflective layer (cholesteric liquid crystal layer).

[0235] [Preparation of Optical Film 5] In Optical Film 5, the number of reflective layers (cholesteric liquid crystal layers) was increased to five, and the coating liquid for the reflective layer and the film thickness were changed as shown in Table 3-3 below. In addition, a light interference layer (positive C plate layer) prepared using the coating liquid for the light interference layer shown below was used as a photo-alignment film for aligning the cholesteric liquid crystal.

[0236] <Coating Solution PC-1 for Optical Interference Layer> The composition shown below was stirred and dissolved in a container kept at 60° C. to prepare Coating Solution PC-1 for Optical Interference Layer.

[0237] ------------------------------------------------ Coating liquid PC-1 for optical interference layer -------------------------------------------------- Methyl isobutyl ketone 3011.0 parts by mass Mixture of the above rod-shaped liquid crystal compounds 100.0 parts by mass Photopolymerization initiator C described below 5.1 parts by mass Photoacid generator described below 3.0 parts by mass Hydrophilic polymer described below 2.0 parts by mass Vertical alignment agent described below 1.9 parts by mass Viscosity reducer described below 4.2 parts by mass Material for interlayer photoalignment film described below 8.0 parts by mass Stabilizer described below 0.2 parts by mass ------------------------------------------------

[0238] Photopolymerization initiator C

[0239] Photoacid generator

[0240] hydrophilic polymer

[0241] Vertical alignment agent

[0242] Viscosity reducer

[0243] Materials for interlayer photo-alignment films

[0244] stabilizers

[0245] A 60 μm thick TAC film (triacetyl cellulose film (TG60, manufactured by Fujifilm Corporation)) was prepared as a support.

[0246] The coating solution for optical interference layer PC-1 prepared above was applied to a support (TAC film) using a wire bar coater, and then dried at 80°C for 60 seconds. Thereafter, the coating solution was dried in a low-oxygen atmosphere (100 ppm) at 78°C with an irradiation dose of 300 mJ / cm. 2 The liquid crystal compound was cured by irradiating it with light from a 365 nm ultraviolet LED lamp, and simultaneously cleaving the cleavage group of the material for the interlayer photo-alignment film. The film was then heated at 115°C for 25 seconds to remove the fluorine-containing substituents. This resulted in the formation of a positive C-plate layer as an optical interference layer having cinnamoyl groups on the outermost surface and a film thickness of 80 nm. The refractive index nI measured using an interference film thickness meter OPTM (manufactured by Otsuka Electronics, analyzed using the least squares method) was 1.57. The Rth measured at a wavelength of 550 nm using an Axoscan (manufactured by Axometrics) was -8 nm.

[0247] Next, the illuminance was 7 mW / cm 2 , irradiation amount 7.9mJ / cm 2 The film was irradiated from the positive C-plate side with polarized UV (wavelength 313 nm). The polarized UV with a wavelength of 313 nm was obtained by passing ultraviolet light emitted from a mercury lamp through a bandpass filter having a transmission band at wavelength 313 nm and a wire grid polarizer. Reflective layer coating solution R-5 was applied using a wire bar coater and then dried at 110°C for 72 seconds. Thereafter, the film was irradiated with polarized UV light at an illuminance of 80 mW / cm at 100°C in a low-oxygen atmosphere (100 ppm or less). 2 , irradiation amount 500mJ / cm 2The green light-reflecting layer (first light-reflecting layer) was formed from a cholesteric liquid crystal layer by irradiating the green light-reflecting layer with light from a metal halide lamp at 1000 kJ / cm2 and curing the layer. The light irradiation was carried out from the cholesteric liquid crystal layer side. The coating thickness was adjusted so that the green light-reflecting layer had a thickness of 2.4 μm after curing.

[0248] Next, a discharge amount of 150 W·min / m was applied to the surface of the green light reflective layer. 2 After corona treatment at 400°C, the reflective layer coating solution D-5 was applied to the corona-treated surface using a wire bar coater. The coating film was then dried at 70°C for 2 minutes, and after the solvent was evaporated, it was heat-aged at 115°C for 3 minutes to obtain a uniformly oriented state. Thereafter, the coating film was kept at 45°C and irradiated with ultraviolet light (300 mJ / cm) using a metal halide lamp under a nitrogen atmosphere. 2 ) and cured to form a blue light reflective layer (second light reflective layer) on the green light reflective layer. Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the film thickness of the blue light reflective layer after curing was 1.7 μm.

[0249] Next, the reflective layer coating solution D-6 was applied onto the blue light reflective layer using a wire bar coater. Subsequently, the coating film was dried at 70°C for 2 minutes, and after the solvent was evaporated, it was heat-aged at 115°C for 3 minutes to obtain a uniformly oriented state. Thereafter, this coating film was kept at 45°C and irradiated with ultraviolet light (300 mJ / cm) using a metal halide lamp under a nitrogen atmosphere. 2 ) and cured to form a second blue light reflective layer (third light reflective layer) on the blue light reflective layer. Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the film thickness of the blue light reflective layer after curing was 3.8 μm.

[0250] Next, the reflective layer coating solution R-6 was applied onto the second blue light reflective layer using a wire bar coater, and then dried at 110°C for 72 seconds. Thereafter, the coating solution was dried in a low-oxygen atmosphere (100 ppm or less) at 100°C with an illuminance of 80 mW and an irradiation dose of 500 mJ / cm. 2The coating was cured by irradiating it with light from a metal halide lamp at 1000 W / m, thereby forming a red light reflective layer (fourth light reflective layer) on the second blue light reflective layer. The light irradiation was carried out from the cholesteric liquid crystal layer side in all cases. The coating thickness was adjusted so that the red light reflective layer after curing had a film thickness of 4.8 μm.

[0251] Next, the red light reflecting layer surface was subjected to a discharge of 150 W·min / m ２ After corona treatment at 400°C, the reflective layer coating solution D-7 was applied to the corona-treated surface using a wire bar coater. The coating film was then dried at 70°C for 2 minutes, and after the solvent was evaporated, it was heat-aged at 115°C for 3 minutes to obtain a uniformly oriented state. Thereafter, the coating film was kept at 45°C and irradiated with ultraviolet light (300 mJ / cm) using a metal halide lamp under a nitrogen atmosphere. 2 ) and cured to form a yellow light-reflecting layer (fifth light-reflecting layer) on the red light-reflecting layer. Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the film thickness of the yellow light-reflecting layer after curing was 3.3 μm.

[0252] The coating liquid for the reflective layer, the amount of chiral agent, the central wavelength of reflection, and the film thickness of each reflective layer of the produced optical film 5 are shown in the table below.

[0253] Reflective layer (cholesteric liquid crystal layer) of optical film 5

[0254] [Preparation of Optical Film 6] A PMMA film (polymethyl methacrylate film) having a thickness of 50 μm was prepared as the optical film 6 having optical isotropy to be used in the molding test.

[0255] [Molding Method 1] Optical film 2 was bonded to a PMMA film via an adhesive sheet (NCF-D692(5)) manufactured by Lintec Corporation, and the separation film was peeled off from the adhesive sheet to expose the adhesive surface, which was then set in a molding device. The molding space within the molding device consisted of box 1 and box 2, separated by optical film 1. A convex meniscus lens LE1076-A manufactured by Thorlab (diameter 2 inches, focal length 100 mm, radius of curvature of the concave surface side 65 mm) was placed as a mold in box 1 below optical film 2, with the concave surface facing up. In addition, box 2 above optical film 1 had a transparent window installed at the top, and an IR light source for heating the optical film was installed outside this window. Between the IR light source and optical film 2, a ring-shaped patterned infrared reflection filter was placed. The filter was cut out to fit the outer periphery of the mold from a cholesteric liquid crystal layer that reflects infrared light with wavelengths of 2.2 μm to 3.0 μm at a reflectance of approximately 50%, and the center was further cut out into a circle with a diameter of 1 inch. The filter was positioned so that the center of the patterned infrared reflection filter was at the center of the mold when viewed from directly above. Next, a vacuum pump was used to evacuate boxes 1 and 2 to a pressure of 0.1 atmospheres or less. Next, in the heating step of optical film 2, infrared light was irradiated to optical film 1 until the center reached 108°C and the edges reached 99°C. The glass transition temperature Tg of the PMMA film used as the support was 105°C, so the aim was to create a state in which the center would easily stretch and the edges would not easily stretch during molding. Next, in a step of pressing the optical film 2 against the mold and deforming it to conform to the shape of the mold, gas was flowed into the box 2 from a gas cylinder to pressurize it to 300 kPa, and the optical film 2 was pressed against the mold. The optical film 2 was attached to the mold via an adhesive sheet, and used as is as the composite lens 1. Finally, the portion of the optical film that protruded from the lens mold was cut out, thereby obtaining the optical film 2 molded into a curved surface and attached to the lens.

[0256] [Molding Method 2] Optical film 2 was bonded to a PMMA film via an adhesive sheet (NCF-D692(5)) manufactured by Lintec Corporation, and the separate film was peeled off from the adhesive sheet to expose the adhesive surface, which was then set in a molding device. The molding space within the molding device consisted of box 1 and box 2, separated by optical film 2. A mold, a convex meniscus lens LE1076-A manufactured by Thorlab (diameter 2 inches, focal length 100 mm, concave side curvature radius 65 mm) expanded with clay, was placed in box 1 below optical film 2, with the concave side facing up. The expansion with clay was performed so that the concave curve of the lens was extended while maintaining almost substantially the same curvature, and the shape of the mold including the lens and clay was 3 inches in diameter and a concave curvature radius of 65 mm. Furthermore, a transparent window was installed on the top of box 2 above optical film 2, and an IR light source for heating optical film 2 was installed outside this window. Next, a vacuum pump was used to evacuate the interiors of boxes 1 and 2 to a pressure of 0.1 atmospheres or less. Next, to heat optical film 2, infrared rays were irradiated and optical film 2 was heated to 108°C at its center. Because the glass transition temperature Tg of the PMMA film used as the support was 105°C, a temperature higher than this was targeted. Next, to press optical film 2 against the mold and deform it to conform to the mold shape, gas was introduced from a gas cylinder into box 2, pressurizing it to 300 kPa, and optical film 2 was pressed against the mold. Optical film 2 was attached to the lens portion of the mold via an adhesive sheet and used as is as composite lens 2. The clay placed outside the lens was removed. Finally, the optical film 2 was cut out by cutting out the portion protruding from the lens, yielding an optical film 2 molded to a curved surface and bonded to the lens. The diameter of the cut optical film 2 was 67% of the diameter of the mold formed by the lens and clay.

[0257] [Molding Method 3] Optical film 2 was bonded to a PMMA film via an adhesive sheet (NCF-D692(5)) manufactured by Lintec Corporation. The separation film was peeled off from the adhesive sheet to expose the adhesive surface, and the resulting product was set in a molding device. The molding space within the molding device consisted of box 1 and box 2, separated by optical film 1. A convex meniscus lens LE1076-A manufactured by Thorlab (diameter 2 inches, focal length 100 mm, radius of curvature on the concave side 65 mm) was placed as a mold in box 1 below optical film 2, with the concave side facing up. Furthermore, box 2 above optical film 2 had a transparent window on the top, and an IR light source for heating the optical film was installed outside this window. Next, a vacuum pump was used to evacuate box 1 and box 2 to a pressure of 0.1 atmospheres or less. Next, in the process of heating optical film 2, infrared light was irradiated and optical film 2 was heated until the center of optical film 2 reached 108°C. Next, in a process of pressing the optical film 2 against the mold and deforming it to conform to the shape of the mold, gas was flowed into the box 2 from a gas cylinder to pressurize it to 300 kPa, and the optical film 2 was pressed against the mold. The pressurization speed until the pressure reached 300 kPa was adjusted so that the temperature of the center immediately after pressing against the mold would be 99°C. Because the glass transition temperature Tg of the PMMA film used as the support was 105°C, the goal was to keep the center easy to stretch during molding while changing the edge to a state that was difficult to stretch midway through molding. The optical film 2 was attached to the mold via an adhesive sheet and used as is as the composite lens 3. Finally, the optical film 2 was cut out by cutting out the portion that protruded from the lens mold, thereby obtaining the optical film 2 molded to a curved surface and bonded to the lens.

[0258] [Molding Method 4] Optical film 2 was bonded to a PMMA film via an adhesive sheet (NCF-D692(5)) manufactured by Lintec Corporation, and the separate film was peeled off from the adhesive sheet to expose the adhesive surface. A convex meniscus lens LE1076-A manufactured by Thorlab (diameter 2 inches, focal length 100 mm, radius of curvature of the concave side 65 mm) was placed as a concave mold with the concave surface facing up. Optical film 2 was placed on the mold with the adhesive surface facing down. This resulted in optical film 2 being restrained by the edge of the concave mold. Next, a convex mold with a radius of curvature of 65 mm was prepared, and the mold was heated to 120°C in an oven. Next, the convex mold was positioned so that the apex of the convex portion was at the center of the concave mold when viewed from directly above, and was slowly pressed against optical film 2. This allows the temperature at the center to rise first during molding, making it more likely to stretch, and as the convex surface is pressed in, the higher temperature region spreads towards the edges. The optical film 2 was attached to the mold via an adhesive sheet, and used as is as a composite lens 4. Finally, the portion of the optical film that protruded from the lens, which was the mold, was cut off, thereby obtaining the optical film 2 molded to a curved surface and attached to the lens.

[0259] Optical films 1, 3, 4 and 5 were molded by molding method 1 to produce complex lenses 5, 6, 7 and 8, respectively.

[0260] [Preparation of Polarizing Plate Laminate] [Preparation of Positive C Plate 1] The film thickness was adjusted with reference to the method described in paragraphs 0132 to 0134 of JP 2016-053709 A to prepare a positive C plate 1. The positive C plate 1 had Re = 0.2 nm and Rth = -310 nm.

[0261] [Preparation of Retardation Layer 1] A reverse dispersion retardation layer 1 was prepared with reference to the method described in paragraphs 0151 to 0163 of JP 2020-084070 A. The retardation layer 1 had Re=146 nm and Rth=73 nm.

[0262] [Preparation of Linear Polarizer] [Preparation of Cellulose Acylate Film 1] (Preparation of Core Layer Cellulose Acylate Dope) The following composition was charged into a mixing tank and stirred to dissolve each component, thereby preparing a cellulose acetate solution to be used as the core layer cellulose acylate dope. ------------------------------------------------ Core Layer Cellulose Acylate Dope------------------------------------------------ - Cellulose acetate having an acetyl substitution degree of 2.88: 100 parts by mass - Polyester compound B described in the examples of JP2015-227955A: 12 parts by mass - Compound F below: 2 parts by mass - Methylene chloride (first solvent): 430 parts by mass - Methanol (second solvent): 64 parts by mass

[0263] Compound F

[0264] (Preparation of Outer Layer Cellulose Acylate Dope) 10 parts by weight of the following matting agent solution was added to 90 parts by weight of the above core layer cellulose acylate dope to prepare a cellulose acetate solution to be used as the outer layer cellulose acylate dope.

[0265] ------------------------------------------------------------------ Matting agent solution -------------------------------------------------- Silica particles with an average particle size of 20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 2 parts by mass Methylene chloride (first solvent) 76 parts by mass Methanol (second solvent) 11 parts by mass The above-mentioned cellulose acylate dope for the core layer 1 part by mass ------------------------------------------------------------------

[0266] (Preparation of Cellulose Acylate Film 1) The core layer cellulose acylate dope and the outer layer cellulose acylate dope were filtered through a filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm. The core layer cellulose acylate dope and the outer layer cellulose acylate dope on both sides of the core layer cellulose acylate dope were simultaneously cast onto a drum at 20°C through a casting nozzle (band caster). The film was then peeled off while still containing approximately 20% solvent by weight. Both ends of the film in the width direction were fixed with tenter clips, and the film was stretched transversely at a stretch ratio of 1.1 times while being dried. The film was then transported between the rolls of a heat treatment device and further dried to produce an optical film with a thickness of 40 μm, designated as Cellulose Acylate Film 1. The in-plane retardation of the resulting Cellulose Acylate Film 1 was 0 nm.

[0267] <Formation of Photo-Alignment Layer PA1>

[0268] The coating liquid S-PA-1 for forming an alignment layer, which will be described later, was continuously applied onto the cellulose acylate film 1 using a wire bar. The support on which the coating film was formed was dried with hot air at 140°C for 120 seconds, and then the coating film was irradiated with polarized ultraviolet light (10 mJ / cm 2 A photo-alignment layer PA1 was formed by irradiating the substrate with light (using an ultra-high pressure mercury lamp). The film thickness was 0.3 μm.

[0269] ------------------------------------------------------------------ (Coating liquid for forming alignment layer S-PA-1) -------------------------------------------------- Polymer M-PA-1 (shown below) 100.00 parts by mass Acid generator PAG-1 (shown below) 5.00 parts by mass Acid generator CPI-110TF (shown below) 0.005 parts by mass Xylene 1220.00 parts by mass Methyl isobutyl ketone 122.00 parts by mass ------------------------------------------------------------------

[0270] Polymer M-PA-1

[0271] Acid generator PAG-1

[0272] Acid generator CPI-110F

[0273] <Formation of Optically Absorbent Anisotropic Layer P1> The following coating solution SP-1 for forming an optically absorbent anisotropic layer was continuously applied onto the obtained alignment layer PA1 using a wire bar. The coating layer P1 was then heated at 140°C for 30 seconds and cooled to room temperature (23°C). It was then heated at 90°C for 60 seconds and cooled again to room temperature. Thereafter, an LED lamp (center wavelength 365 nm) was used to apply the coating solution SP-1 continuously onto the obtained alignment layer PA1 using a wire bar. The coating layer P1 was then heated at 140°C for 30 seconds and cooled to room temperature (23°C). The coating layer P1 was then heated at 90°C for 60 seconds and cooled again to room temperature. Thereafter, an LED lamp (center wavelength 365 nm) was used to apply the coating solution SP-1 continuously onto the obtained alignment layer PA1 using a wire bar. The coating layer P1 was then heated at 90°C for 60 seconds and cooled again to room temperature. The coating layer P1 was then heated at an illuminance of 200 mW / cm ２ The light was irradiated for 2 seconds under the irradiation conditions of 1.6 μm to form an optically absorptive anisotropic layer P1 on the alignment layer PA1.

[0274] 0.25 parts by mass of dichroic substance D-1 below 0.36 parts by mass of dichroic substance D-2 below 0.59 parts by mass of dichroic substance D-3 below 2.21 parts by mass of polymer liquid crystal compound M-P-1 below 1.36 parts by mass of low molecular weight liquid crystal compound M-1 below 0.200 parts by mass of polymerization initiator IRGACURE OXE-02 (manufactured by BASF) 0.026 parts by mass of surfactant F-1 below 46.00 parts by mass of cyclopentanone 46.00 parts by mass of tetrahydrofuran 46.00 parts by mass of benzyl alcohol ----------------------------------------------------------------------------------

[0275] Dichroic substance D-1

[0276] Dichroic substance D-2

[0277] Dichroic substance D-3

[0278] Polymer liquid crystal compound M-P-1

[0279] Low molecular liquid crystal compound M-1

[0280] Surfactant F-1

[0281] The obtained retardation layer 1 was laminated to the opposite side of the support of the obtained positive C plate 1. Next, the optically absorbing anisotropic layer P1 was transferred. The layer on the opposite side of the optically absorbing anisotropic layer P1 from the temporary support was transferred to the positive C plate 1 side. The temporary support of the optically absorbing anisotropic layer P1 was peeled off and removed after transfer. The optically absorbing anisotropic layer P1 was transferred using the following procedure. (1) The support side of the positive C plate 1 was coated with UV adhesive Chemiseal U2084B (manufactured by Chemitech Co., Ltd., refractive index after curing: n 1.60) to a thickness of 2 μm using a wire bar coater. The optically absorbing anisotropic layer P1 was laminated thereon using a laminator so that the side opposite the temporary support of the optically absorbing anisotropic layer P1 was in contact with the UV adhesive. (2) After nitrogen purging in a purge box until the oxygen concentration was 100 ppm or less, the optically absorbing anisotropic layer P1 was cured by irradiating ultraviolet light from a high-pressure mercury lamp from the temporary support side. Illuminance is 25mW / cm 2 , the irradiation dose is 1000 mJ / cm 2 (3) Finally, the temporary support of the optically absorptive anisotropic layer P1 was peeled off. The layers were laminated such that the slow axis of the retardation layer 1 and the absorption axis of the optically absorptive anisotropic layer P1 formed an angle of 45°. Finally, the support of the positive C plate 1 was peeled off. In this manner, a polarizing plate laminate was produced. It was confirmed that when right-handed circularly polarized light was incident on the produced polarizing plate laminate from the positive C plate side, substantially most of the visible light was absorbed, and when left-handed circularly polarized light was incident, substantially most of the visible light was transmitted.

[0282] [Preparation of Laminated Optical Body 1 and Composite Lens 9] The surface of the optical film 5 on the yellow light-reflecting layer (fifth light-reflecting layer) side was placed opposite the surface of the prepared polarizing plate laminate opposite the light-absorbing anisotropic layer P1, and the polarizing plate laminate was laminated via an adhesive sheet (NCF-D692(5)) manufactured by Lintec Corporation. After lamination, the tack film used as a support for the optical film 5 was peeled off, and a laminated optical body 1 consisting of a cholesteric liquid crystal, a retardation film, and a light-absorbing anisotropic layer was obtained.

[0283] The produced laminated optical body 1 was molded by molding method 1 to produce a composite lens 9. At this time, molding was performed while the surface of the laminated optical body 1 on the optical film 5 side was positioned on the lens side.

[0284] [Preparation of Complex Lenses 11 to 14 Using Optical Film 6] Complex lenses 11 to 14 were prepared by molding the optical film 6 using molding methods 1 to 4.

[0285] [Formation of a Half Mirror on a Complex Lens] A half mirror was formed by vapor-depositing aluminum on the convex side of complex lens 1 (a convex meniscus lens LE1076-A (diameter 2 inches, focal length 100 mm) manufactured by Thorlab with optical film 2 attached to the concave side) to give a reflectance of 40%. The reflection spectra of the center and edges of complex lens 1 were measured using a spectrophotometer (V-550 manufactured by JASCO Corporation) equipped with a large integrating sphere device (ILV-471 manufactured by JASCO Corporation). The deviation in the band width of the reflection spectrum between the center and edges was 0.8%. Complex lenses 2 to 7 were also vapor-deposited with aluminum in a similar manner. For complex lenses 6, 7, and 8, which used optical films 3, 4, and 5 that had not been photoisomerized, the deviation in the band width of the reflection spectrum between the center and edges was 2.8%, respectively.

[0286] Examples 1 to 8 A virtual reality display device "Huawei VR Glass" manufactured by Huawei, which is a virtual reality display device employing a reciprocating optical system, was disassembled, and all of the composite lenses were removed. In place of the removed composite lens, composite lens 1 bonded to optical film 2 was incorporated into the main body, and the polarizing plate laminate was placed between composite lens 1 and the user's eye, with the light-absorbing anisotropic layer P1 side facing the eye, thereby producing the virtual reality display device of Example 1. In the produced virtual reality display device, a black and white checkered pattern was displayed on the image display panel, and ghost visibility was visually evaluated using the following four-point scale.

[0287] <Ghost evaluation> A: Slight ghost is visible but not bothersome. B: Weak ghost is visible. C: Somewhat strong ghost is visible. D: Strong ghost is visible.

[0288] Furthermore, virtual reality display devices of Examples 2 to 8 were produced in the same manner using the composite lenses 2 to 8, and ghost visibility was evaluated. The molding method and type of optical film used in each Example are shown in Table 4.

[0289] Example 9 A virtual reality display device "Huawei VR Glass" manufactured by Huawei, which is a virtual reality display device employing a reciprocating optical system, was disassembled, and all of the compound lenses were removed. A virtual reality display device of Example 9 was fabricated by incorporating a compound lens 9 bonded with a laminated optical body 1 into the main body in place of the removed compound lens. Similarly, a black and white checkered pattern was displayed on the image display panel of the fabricated virtual reality display device, and ghost visibility was evaluated.

[0290] Examples 11 to 14 Compound lenses 11 to 14 using the optical film 6 were designated as Examples 11 to 14.

[0291] <Measurement of Retardation> For composite lenses 1 to 9 in Examples 1 to 9 and composite lenses 11 to 14 in Examples 11 to 14, small pieces of the optical film at the center and edge were peeled off and removed from the composite lenses, and the retardation (in-plane retardation) was measured using an Axoscan. The positions of the small edge pieces were sampled at eight points 5 mm from the edge of the lens at 45-degree intervals in the azimuthal direction. The maximum of the retardations measured at the eight sampled points was taken as the retardation at the edge of the optical film. In Examples 1 to 9, where the optical film had a cholesteric liquid crystal layer, the evaluation wavelength was set according to the cholesteric liquid crystal layer with the shortest selected central wavelength. The evaluation wavelength differed between the edge and the center because the half-width on the short wavelength side differed due to the different stretching ratios between the edge and the center.

[0292] The composite lens, molding method, and cholesteric layer in each example are shown in Table 4 below, the evaluation results of ghost visibility are shown in Table 5 below, and the measurement results of retardation are shown in Table 5 below. Note that for Examples 11 to 14, no evaluation of ghost was performed, and only the retardation was measured.

[0293] Table 4: Complex lenses, molding methods and cholesteric layers in each example

[0294] Table 5. Evaluation results of ghost visibility

[0295] As shown in Table 5, the virtual reality display devices of Examples 1 to 4, 8, and 9 had good ghosting across the entire field of view. Furthermore, the color change in the white parts of the black and white checkered pattern was not noticeable. In Examples 5 and 6, slightly strong ghosting was visible at the edges, but was within the tolerance range. Furthermore, in Example 6, a weak ghosting was visible in the center of the field of view. In Example 5, the color change in the white parts of the black and white checkered pattern was not noticeable, while in Example 6, the color change in the white parts of the black and white checkered pattern was noticeable. In Example 7, a weak ghosting was visible in the center of the field of view, but not at the edges. In Example 7, the color change in the white parts of the black and white checkered pattern was noticeable.

[0296] Table 6: Evaluation of retardation for each example

[0297] As shown in Table 6, optical films 1 to 5 having a cholesteric liquid crystal layer molded into the shape of a complex lens by the molding method of the present invention have a post-molding phase difference, i.e., in-plane retardation, of less than 2% of the evaluation wavelength (evaluation wavelength) at both the center and the edge (outer edge). Optical film 6, which uses a PMMA film molded into the shape of a complex lens by the molding method of the present invention, also has a post-molding phase difference, i.e., in-plane retardation, of less than 11 nm at both the center and the edge (outer edge). As described above, according to the molding method of the present invention, the phase difference, i.e., in-plane retardation, of the optical film is kept low at both the center and the edge, even after molding.

[0298] [Example of Second Embodiment] [Preparation of Coating Liquids R-1 to R-4 for Cholesteric Layer]

[0299] The compositions shown below were stirred and dissolved in a container kept at 70°C to prepare coating solutions R-1 to R-4 for the cholesteric layer. Here, R means a coating solution using rod-like liquid crystals. The amount of chiral agent contained in each coating solution for the cholesteric layer is shown in Table 7.

[0300] ------------------------------------------------------------------ Coating liquid R-1 for cholesteric layer -------------------------------------------------- Methyl ethyl ketone 120.9 parts by mass Cyclohexanone 21.3 parts by mass Mixture of rod-shaped liquid crystals shown below 100.0 parts by mass Polymerization initiator LC-1-1 3.00 parts by mass Chiral agent A shown below in Table 7 Surfactant F1 shown below 0.027 parts by mass Surfactant F2 shown below 0.067 parts by mass

[0301] Table 7. Amount of chiral agent in coating solution containing rod-shaped liquid crystal

[0302]

[0303] Rod-like liquid crystal mixture

[0304] In the above mixture, the numerical values ​​are in mass %. R is a group bonded via an oxygen atom. Furthermore, the average molar absorption coefficient of the above rod-shaped liquid crystal in the wavelength range of 300 to 400 nm was 140 / mol cm.

[0305] Chiral agent A

[0306]

[0307] Surfactant F1

[0308]

[0309] Surfactant F2

[0310]

[0311] Polymerization initiator LC-1-1

[0312]

[0313] The chiral agent A is a chiral agent whose helical twisting power (HTP) is reduced by light.

[0314] (Coating Solutions D-1 to D-4 for Cholesteric Layer) The compositions shown below were stirred and dissolved in a container kept at 50°C to prepare Coating Solutions D-1 to D-4 for Cholesteric Layer. Here, D means a coating solution using a discotic liquid crystal. The amount of chiral agent contained in each coating solution for cholesteric layer is shown in Table 8.

[0315] -------------------------------------------------- Coating liquid D-1 for cholesteric layer -------------------------------------------------- 80 parts by mass of the following discotic liquid crystal (A) 20 parts by mass of the following discotic liquid crystal (B) Polymerizable monomer E1 10 parts by mass Surfactant F4 0.3 parts by mass Polymerization initiator LC-1-1 3 parts by mass Chiral agent A See Table 8 Methyl ethyl ketone 290 parts by mass Cyclohexanone 50 parts by mass --------------------------------------------------

[0316] Table 8. Amount of chiral agent in coating solution containing discotic liquid crystal

[0317]

[0318] Discotic liquid crystal (A)

[0319]

[0320] Discotic liquid crystal (B)

[0321]

[0322] Polymerizable Monomer E1

[0323]

[0324] Surfactant F4

[0325]

[0326] [Preparation of Laminate 1] A 50 μm thick PET (polyethylene terephthalate) film (A4100, manufactured by Toyobo Co., Ltd.) was prepared as a temporary support. This PET film had an easy-adhesion layer on one side.

[0327] The surface of the PET film without the easy-adhesion layer was rubbed, and the cholesteric liquid crystal coating solution R-1 prepared above was applied using a wire bar coater. The film was then dried at 110°C for 1 minute, and after the solvent was evaporated, the film was heated and aged at 100°C for 1 minute to obtain a cholesteric liquid crystal film in which a uniformly oriented cholesteric liquid crystal phase was coated on the support. This cholesteric liquid crystal film was placed on a stage with a rotation mechanism. Next, a microwave-based ultraviolet (UV) light source (Light Hammer 10, 240 W / cm, manufactured by Fusion UV Systems) equipped with a D-bulb with a strong emission spectrum in the 350-400 nm range was used. A wire-grid polarizing filter (ProFlux PPL02 (high transmittance type), manufactured by Moxtek) was placed 10 cm away from the irradiation surface, and the cholesteric liquid crystal film heated to 80°C was rotated while irradiated with polarized UV light through an exposure mask in a nitrogen atmosphere. A conceptual diagram of the exposure mask used here is shown in Figure 11. The exposure mask shown in Figure 11 and the exposure method using this exposure mask are described below. The exposure mask was designed so that polarized UV light was transmitted through a triangular region A symmetrical about the y-axis from the center of the mask, and the transmittance was continuously varied from 0% to 100% from the center to the edge along the y-axis. The length from the center to the side perpendicular to the x-axis of the triangle was 1 inch. While rotating the cholesteric liquid crystal film, the cholesteric liquid crystal film was irradiated with polarized UV light parallel to the y-axis in FIG. 11 through the exposure mask in FIG. 11, and the irradiance and dose were 0 mW / cm at the center. 2 and 0 mJ / cm 2 The irradiation dose is 200 mW / cm at the edge. 2 and 300 mJ / cm 2 As a result, a slow axis was formed that changed concentrically around the center of rotation. A conceptual diagram of the formed slow axis is shown in Figure 12. After that, the film was further irradiated with light at an illuminance of 80 mW / cm under a nitrogen atmosphere (100 ppm or less) at 100°C. ２ , irradiation amount 500mJ / cm ２The cholesteric liquid crystal was cured by irradiating the film with light from a metal halide lamp so that the red light reflective layer was formed from the cholesteric liquid crystal layer. The light irradiation was carried out from the cholesteric liquid crystal layer side. The red light reflective layer after curing had a thickness of 4.5 μm.

[0328] Next, the red light reflecting layer surface was subjected to a discharge of 150 W·min / m ２ After corona treatment, the cholesteric liquid crystal layer coating solution D-2 was applied to the corona-treated surface using a wire bar coater. The coating film was then dried at 100°C for 2 minutes, and after evaporating the solvent, it was heat-aged at 115°C for 5 minutes to obtain a cholesteric liquid crystal film in which a uniformly oriented cholesteric liquid crystal phase was coated on the support. Thereafter, in the same manner as for the red light-reflecting layer, the film was irradiated with polarized UV light through a mask and with UV light from a metal halide lamp, forming a yellow light-reflecting layer on the red light-reflecting layer. The coating thickness was adjusted so that the film thickness of the yellow light-reflecting layer after curing would be 3.3 μm.

[0329] Next, the cholesteric liquid crystal layer coating solution R-3 was applied onto the yellow light-reflecting layer using a wire bar coater, followed by drying at 110°C for 1 minute. After evaporating the solvent, the film was heat-aged at 100°C for 1 minute to obtain a cholesteric liquid crystal film in which a uniformly oriented cholesteric liquid crystal phase was coated on the support. Thereafter, in the same manner as for the red light-reflecting layer, the film was irradiated with polarized UV light through a mask and with UV light from a metal halide lamp, to form a green light-reflecting layer on the yellow light-reflecting layer. The coating thickness was adjusted so that the film thickness of the green light-reflecting layer after curing would be 2.7 μm.

[0330] Next, the green light reflecting layer surface was subjected to a discharge of 150 W·min / m ２After corona treatment, cholesteric liquid crystal layer coating solution D-4 was applied to the corona-treated surface using a wire bar coater. The coating film was then dried at 100°C for 2 minutes, and after evaporating the solvent, it was heat-aged at 115°C for 5 minutes to obtain a cholesteric liquid crystal film in which a uniformly aligned cholesteric liquid crystal phase was coated on the support. Then, using the same method as for the red reflective layer, the film was irradiated with polarized UV light through a mask and UV light from a metal halide lamp to form a blue light reflective layer on the green light reflective layer. The coating thickness was adjusted so that the film thickness of the blue light reflective layer after curing was 2.5 μm. This resulted in the production of a laminate 1 having multiple cholesteric liquid crystal layers. The cholesteric liquid crystal layer coating solutions used and their film thicknesses are shown in Table 9-1.

[0331]

[0332] [Preparation of Laminate 2] Laminate 2 was prepared in the same manner as laminate 1, except that the number of layers was increased to 8 and the coating solution for the cholesteric liquid crystal layer and the film thickness were changed as shown in Table 9-2 below.

[0333]

[0334] [Preparation of Laminate 3] Laminate 3 was prepared in the same process as for preparing laminate 1, except that the irradiation with polarized UV light using an exposure mask was not carried out.

[0335] [Preparation of Laminate 4] Laminate 4 was prepared in the same process as that for preparing laminate 2, except that the irradiation with polarized UV light using an exposure mask was not carried out.

[0336] [Preparation of Optical Laminate] Laminate 1 was attached to a PMMA film via an adhesive sheet "NCF-D692(5)" manufactured by Lintec Corporation, and the PET support was peeled off to obtain Optical Laminate 1. Optical Laminates 2 to 4 were obtained in the same manner as Optical Laminate 1, except that Laminate 1 was changed to Laminates 2 to 4.

[0337] [Evaluation of Retardation and Slow Axis] The slow axis and retardation of the optical laminate 1 were measured using an ellipsometer M-2000UI manufactured by J. A. Woollam. The optical laminate 1 had a slow axis substantially concentrically centered around the center of rotation during mask exposure. The retardation of the optical laminate 1 at the center of rotation during mask exposure was measured and found to be 0 nm. The retardation of the optical laminate 1 at a position 0.2 inches away from the center of rotation during mask exposure in the radial direction of the concentric circles was 2 nm. The retardation of the optical laminate 1 at a position 0.6 inches away from the center of rotation during mask exposure in the radial direction of the concentric circles was 12 nm. The retardation of the optical laminate 1 at a position 0.8 inches away from the center of rotation during mask exposure in the radial direction of the concentric circles was 23 nm. Table 10 shows the results of similar evaluation of optical laminates 2 to 4. Optical laminates 1 and 2, each having a cholesteric liquid crystal layer irradiated with polarized UV light through a mask using the above method, had different in-plane retardations and substantially concentric slow axes. On the other hand, optical laminates 3 and 4, each having a cholesteric liquid crystal layer not irradiated with polarized UV light, had no retardation.

[0338]

[0339] [Molding method] The optical laminate 1 was molded using a vacuum molding method onto the concave surface of a convex meniscus lens LE1076-A (diameter 2 inches, focal length 100 mm, radius of curvature of the concave surface side 65 mm) manufactured by Thorlab, Inc., via an adhesive sheet. Finally, the portion of the optical laminate 1 that protruded from the lens was cut off, thereby obtaining an optical component 1 including a cholesteric liquid crystal layer molded onto a curved surface.

[0340] Optical component 2 was obtained in the same manner as optical component 1, except that optical laminate 2 was used instead of optical laminate 1.

[0341] Optical component 3 was obtained in the same manner as optical component 1, except that optical laminate 3 was used instead of optical laminate 1.

[0342] Optical component 4 was obtained in the same manner as optical component 1, except that optical laminate 4 was used instead of optical laminate 1.

[0343] [Preparation of Polarizing Plate Laminate]

[0344] [Preparation of Positive C Plate 1] The film thickness was adjusted with reference to the method described in paragraphs 0132 to 0134 of JP 2016-053709 A to prepare a positive C plate 1. The positive C plate 1 had Re=0.2 nm and Rth=−310 nm.

[0345] [Preparation of Retardation Layer 1] A reverse dispersion retardation layer 1 was prepared with reference to the method described in paragraphs 0151 to 0163 of JP 2020-084070 A. The retardation layer 1 had Re=146 nm and Rth=73 nm.

[0346] [Preparation of Linear Polarizer]

[0347] [Preparation of Cellulose Acylate Film 1] (Preparation of Core Layer Cellulose Acylate Dope) The following composition was charged into a mixing tank and stirred to dissolve each component, thereby preparing a cellulose acetate solution to be used as the core layer cellulose acylate dope. ------------------------------------------------ Core Layer Cellulose Acylate Dope------------------------------------------------ - Cellulose acetate having an acetyl substitution degree of 2.88: 100 parts by mass - Polyester compound B described in the examples of JP 2015-227955 A: 12 parts by mass - Compound F below: 2 parts by mass - Methylene chloride (first solvent): 430 parts by mass - Methanol (second solvent): 64 parts by mass

[0348] Compound F

[0349]

[0350] (Preparation of Outer Layer Cellulose Acylate Dope) 10 parts by weight of the following matting agent solution was added to 90 parts by weight of the above core layer cellulose acylate dope to prepare a cellulose acetate solution to be used as the outer layer cellulose acylate dope.

[0351] ------------------------------------------------------------------ Matting agent solution -------------------------------------------------- Silica particles with an average particle size of 20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 2 parts by mass Methylene chloride (first solvent) 76 parts by mass Methanol (second solvent) 11 parts by mass The above-mentioned cellulose acylate dope for the core layer 1 part by mass ------------------------------------------------------------------

[0352] (Preparation of Cellulose Acylate Film 1) The core layer cellulose acylate dope and the outer layer cellulose acylate dope were filtered through a filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm. The core layer cellulose acylate dope and the outer layer cellulose acylate dope on both sides were simultaneously cast onto a drum at 20°C from a casting nozzle (band caster). The film was then peeled off while still containing approximately 20% solvent by weight. Both ends of the film in the width direction were fixed with tenter clips, and the film was stretched transversely at a stretch ratio of 1.1 times while being dried. The film was then transported between the rolls of a heat treatment device and further dried to produce an optical film with a thickness of 40 μm, designated as Cellulose Acylate Film 1. The in-plane retardation of the resulting Cellulose Acylate Film 1 was 0 nm.

[0353] <Formation of Photo-Alignment Layer PA1>

[0354] The coating liquid S-PA-1 for forming an alignment layer, which will be described later, was continuously applied onto the cellulose acylate film 1 using a wire bar. The support on which the coating film was formed was dried with hot air at 140°C for 120 seconds, and then the coating film was irradiated with polarized ultraviolet light (10 mJ / cm ２ A photo-alignment layer PA1 was formed by irradiating the substrate with light (using an ultra-high pressure mercury lamp). The film thickness was 0.3 μm.

[0355] -------------------------------------------------- (Coating liquid for forming alignment layer S-PA-1) -------------------------------------------------- Polymer M-PA-1 shown below: 100.00 parts by mass Acid generator PAG-1 shown below: 5.00 parts by mass Acid generator CPI-110TF shown below: 0.005 parts by mass Xylene: 1,220.00 parts by mass Methyl isobutyl ketone: 122.00 parts by mass

[0356] Polymer M-PA-1

[0357]

[0358] Acid generator PAG-1

[0359]

[0360] Acid generator CPI-110F

[0361]

[0362] <Formation of Optically Absorbent Anisotropic Layer P1> The following coating solution SP-1 for forming an optically absorbent anisotropic layer was continuously applied onto the obtained alignment layer PA1 using a wire bar. The coating layer P1 was then heated at 140°C for 30 seconds and cooled to room temperature (23°C). It was then heated at 90°C for 60 seconds and cooled again to room temperature. Thereafter, an LED lamp (center wavelength 365 nm) was used to apply the coating solution SP-1 continuously onto the obtained alignment layer PA1 using a wire bar. The coating layer P1 was then heated at 140°C for 30 seconds and cooled to room temperature (23°C). The coating layer P1 was then heated at 90°C for 60 seconds and cooled again to room temperature. Thereafter, an LED lamp (center wavelength 365 nm) was used to apply the coating solution SP-1 continuously onto the obtained alignment layer PA1 using a wire bar. The coating layer P1 was then heated at 90°C for 60 seconds and cooled again to room temperature. The coating layer P1 was then heated at an illuminance of 200 mW / cm ２ The light was irradiated for 2 seconds under the irradiation conditions of 1.6 μm to form an optically absorptive anisotropic layer P1 on the alignment layer PA1.

[0363] 0.25 parts by mass of dichroic substance D-1 below 0.36 parts by mass of dichroic substance D-2 below 0.59 parts by mass of dichroic substance D-3 below 2.21 parts by mass of polymer liquid crystal compound M-P-1 below 1.36 parts by mass of low molecular weight liquid crystal compound M-1 below 0.200 parts by mass of polymerization initiator IRGACURE OXE-02 (manufactured by BASF) 0.026 parts by mass of surfactant F-1 below 46.00 parts by mass of cyclopentanone 46.00 parts by mass of tetrahydrofuran 46.00 parts by mass of benzyl alcohol ----------------------------------------------------------------------------------

[0364] Dichroic substance D-1

[0365]

[0366] Dichroic substance D-2

[0367]

[0368] Dichroic substance D-3

[0369]

[0370] Polymer liquid crystal compound M-P-1

[0371]

[0372] Low molecular liquid crystal compound M-1

[0373]

[0374] Surfactant F-1

[0375]

[0376] The obtained retardation layer 1 was laminated to the opposite side of the support of the obtained positive C plate 1. Next, the optically absorbing anisotropic layer P1 was transferred. The layer opposite the temporary support of the optically absorbing anisotropic layer P1 was transferred to the positive C plate 1 side. The temporary support of the optically absorbing anisotropic layer P1 was peeled off and removed after transfer. The optically absorbing anisotropic layer P1 was transferred using the following procedure. (1) UV adhesive Chemiseal U2084B (manufactured by Chemitech Corporation, refractive index after curing: n 1.60) was applied to the support side of the positive C plate 1 with a wire bar coater to a thickness of 2 μm. The optically absorbing anisotropic layer P1 was laminated thereon with a laminator so that the side opposite the temporary support of the optically absorbing anisotropic layer P1 was in contact with the UV adhesive. (2) After nitrogen purging in a purge box until the oxygen concentration was 100 ppm or less, the optically absorbing anisotropic layer P1 was cured by irradiating ultraviolet light from a high-pressure mercury lamp from the temporary support side. Illuminance is 25mW / cm ２ , the irradiation dose is 1000 mJ / cm ２ (3) Finally, the temporary support of the optically absorptive anisotropic layer P1 was peeled off. The layers were laminated such that the slow axis of the retardation layer 1 and the absorption axis of the optically absorptive anisotropic layer P1 formed an angle of 45°. Finally, the support of the positive C plate 1 was peeled off. In this way, a polarizing plate laminate was obtained. It was confirmed that when right-handed circularly polarized light was incident on this polarizing plate laminate from the positive C plate side, substantially most of the visible light was absorbed, and when left-handed circularly polarized light was incident, substantially most of the visible light was transmitted.

[0377] [Formation of Half Mirror on Optical Component] Aluminum was vapor-deposited on the convex surface of optical component 1 to give a reflectance of 40%, forming a half mirror. Similarly, aluminum was vapor-deposited on optical components 2 to 4.

[0378] Example 2-1: A virtual reality display device "Huawei VR Glass" manufactured by Huawei, which employs a reciprocating optical system, was disassembled, and all of the composite lenses were removed. Instead, optical component 1 was incorporated into the main body, and the polarizing plate laminate was placed between optical component 1 and the eye so that the light-absorbing anisotropic layer P1 side was positioned toward the eye, thereby producing the virtual reality display device of Example 2-1. Furthermore, optical component 1 was replaced with optical components 2 to 4, respectively, and virtual reality display devices of Example 2-2 and Comparative Examples 2-1 and 2-2 were produced using the same procedure. <Evaluation of Light Leakage> In the virtual reality display devices of Examples 2-1 to 2-2 and Comparative Examples 2-1 to 2-2, a black and white checkered pattern was displayed on the image display, and the degree of light leakage was visually evaluated using the following three-point scale. Note that light leakage causes a double image to be visible, reducing the contrast of the corresponding area. A: The double image is barely visible. B: The double image is slightly visible, but not bothersome. C: The double image is clearly visible. The results are shown in Table 11.

[0379] <Evaluation of Display Uniformity> In the virtual reality display devices fabricated in Examples 2-1 to 2-2 and Comparative Examples 2-1 to 2-2, a black and white checkered pattern was displayed on the image display device, and the display uniformity was visually evaluated using the following three-point scale: A: Uniform display across the entire surface B: Part of the image is distorted unevenly C: Most of the image is distorted The results are shown in Table 11.

[0380] Table 11 Evaluation results of the virtual reality display device of the example

[0381]

[0382] The above results show that the slow axes of the cholesteric liquid crystal layer after concave molding, which were concentrically arranged before concave molding, were eliminated by concave molding, and as a result, the retardation was 10 nm or less, and the evaluations of light leakage and display uniformity were good. From these results, the effects of the present invention are clear.

[0383] 31 First light-reflecting layer 32 Second light-reflecting layer 33 Third light-reflecting layer 34 Fourth light-reflecting layer 100 Laminated optical body 101 Anti-reflection layer 102 Positive C plate 103 Optical film 104 Positive C plate 105 Retardation layer 106 Linear polarizer 120 Support 124 Alignment film 126 Cholesteric liquid crystal layer 132 Liquid crystal compound 200 Lens 300 Half mirror 400 Circular polarizer (reflective circular polarizer) 500 Image display panel 1000 Light ray 2000 Light ray forming ghost

Claims

1. a heating step of heating the optical film; a molding step of pressing the optical film against a mold and deforming the optical film to conform to the shape of the mold; and A method for forming an optical film, comprising: The molding method, wherein the heating step is a step of heating the optical film by irradiating it with infrared rays, and the amount of irradiation of the infrared rays has an in-plane distribution on the optical film.

2. the mold is a non-developable concave surface having a positive Gaussian curvature, and when an in-plane position of the optical film is projected onto the mold from a normal direction of a main surface of the optical film, The molding method according to claim 1 , wherein an amount of infrared radiation irradiated to the optical film at a vertex of the concave surface is greater than an amount of infrared radiation irradiated to the optical film at an end of the concave surface.

3. a heating step of heating the optical film; a molding step of pressing the optical film against a mold and deforming the optical film to conform to the shape of the mold; and A method for forming an optical film, comprising: the surface of the mold in contact with the optical film is a non-developable concave surface having a positive Gaussian curvature, and the outer circumferential shape is an ellipse; a cut shape in the cutting step is an ellipse, and a major axis of an elliptical outer periphery of the optical film cut out by cutting is greater than 50% and smaller than 95% of a major axis of the elliptical outer periphery of the mold.

4. a heating step of heating the optical film; a molding step of pressing the optical film against a mold and deforming the optical film to conform to the shape of the mold; and A method for forming an optical film, comprising: In the heating step, a region of the optical film in contact with the mold is heated to a temperature higher than a glass transition temperature Tg of the optical film; a molding method in which, in the molding step, pressing of the optical film against the mold is controlled so that a region of the optical film in contact with the mold has a temperature lower than a glass transition temperature Tg immediately after the optical film comes into contact with the mold.

5. a heating step of heating the mold; a molding step of pressing the heated mold against an optical film to deform the film in accordance with the shape of the mold; and A method for forming an optical film, comprising: the mold is a non-developable convex surface with a positive Gaussian curvature; In the molding step, an apex of a convex surface of the mold is pressed against a center of the optical film.

6. the cut shape of the optical film in the cutting step is an ellipse, The molding method according to claim 5 , wherein in the molding step, the optical film is pressed against the mold while being constrained in a position on an elliptical line that becomes the cut shape.

7. A cholesteric liquid crystal layer, the cholesteric liquid crystal layer has a retardation region in which the retardation increases from the center to the outside, A cholesteric liquid crystal layer, wherein in the retardation region, a direction of a slow axis at a point in the retardation region is perpendicular to a direction from the center toward the point.

8. An optical laminate comprising a plurality of cholesteric liquid crystal layers according to claim 7.

9. 9. The optical laminate according to claim 8, wherein the cholesteric liquid crystal layer formed using a rod-shaped liquid crystal compound and the cholesteric liquid crystal layer formed using a discotic liquid crystal compound are alternately laminated.

10. a cholesteric liquid crystal layer producing step of producing the cholesteric liquid crystal layer according to claim 7; A method for producing a curved optically functional layer, comprising a molding step of performing curved molding on the cholesteric liquid crystal layer so as to eliminate the retardation of the cholesteric liquid crystal layer.

11. 11. The method for producing a curved optically functional layer according to claim 10, wherein in the molding step, the cholesteric liquid crystal layer is placed on a mold having a concave molding surface so that a bottom of the concave molding surface of the mold coincides with a center of the cholesteric liquid crystal layer, and the cholesteric liquid crystal layer is deformed to conform to the concave molding surface.

12. An optical film having a non-developable surface with a positive Gaussian curvature, the optical film is a cholesteric liquid crystal layer, When the evaluation wavelength of the in-plane retardation is set to a wavelength obtained by subtracting 20 nm from the half-value wavelength on the side shorter than the selective reflection central wavelength in the cholesteric liquid crystal layer, The in-plane retardation A at the center of the cholesteric liquid crystal layer at the evaluation wavelength is less than 2% of the evaluation wavelength, and an in-plane retardation B at the evaluation wavelength at an outer edge of the cholesteric liquid crystal layer is less than 2% of the evaluation wavelength;

13. An optical film having a non-developable surface with a positive Gaussian curvature, The optical film does not have selective reflection properties, The in-plane retardation A at the center of the optical film at a wavelength of 550 nm is less than 11 nm, and The optical film has an in-plane retardation B at an outer edge of the optical film at a wavelength of 550 nm of less than 11 nm.

14. The optical film according to claim 12 or 13, wherein the peripheral shape is elliptical.

15. An optical film as described in claim 12, wherein the cholesteric liquid crystal layer has a helical pitch that varies within a plane.