Reflective member for head-up display system and head-up display system

Abstract

The present invention addresses the problem of providing a reflective member for a head-up display system, which is capable of suppressing reflection of external light and has a wide range of an eyebox when built into a head-up display system. A reflective member for a head-up display system according to the present invention is disposed between a light source and a windshield glass in a head-up display system, and includes a cholesteric liquid crystal layer. In a cross section perpendicular to one main surface of the cholesteric liquid crystal layer, the arrangement direction of bright and dark parts derived from a cholesteric liquid crystal phase observed with a scanning electron microscope is inclined with respect to the one main surface of the cholesteric liquid crystal layer. In the cross section, the inclination of a helical axis of the cholesteric liquid crystal phase changes in an in-plane direction.

Description

Reflective material for head-up display system, head-up display system

[0001] The present invention relates to a reflective member for a head-up display system and a head-up display system.

[0002] Image projection systems that project various images, text information, etc. onto a screen are widely used. For example, Patent Document 1 discloses a so-called head-up display system as one type of in-vehicle display that projects an image displayed on a display element onto a windshield glass or the like to convey various information to the driver.

[0003] US Publication No. 2023 / 0070075

[0004] The present inventors have studied a head-up display system using a display element as described in Patent Document 1, and have found that when a virtual image is visually recognized, the visibility of the virtual image is poor due to reflection of external light (e.g., sunlight), etc. Furthermore, a head-up display system is also required to have a wide eyebox range.

[0005] In view of the above circumstances, an object of the present invention is to provide a reflective member for a head-up display system that can suppress reflection of external light and has a wide eyebox range when incorporated into the head-up display system. Another object of the present invention is to provide a head-up display system.

[0006] The present inventors have found that the above problems can be solved by the following configuration.

[0007] [1] A reflective member for a head-up display system disposed between a light source and a windshield glass in a head-up display system, the reflective member for a head-up display system including a cholesteric liquid crystal layer, wherein, in a cross section perpendicular to one main surface of the cholesteric liquid crystal layer, the alignment direction of light and dark regions derived from the cholesteric liquid crystal phase observed with a scanning electron microscope is tilted with respect to one main surface of the cholesteric liquid crystal layer, and in the cross section, the tilt of the helical axis of the cholesteric liquid crystal phase varies in an in-plane direction. [2] The reflective member for a head-up display system according to [1], wherein, in the cross section, along one in-plane direction of the cholesteric liquid crystal layer, there is a region where the tilt of the helical axis of the cholesteric liquid crystal phase with respect to the main surface of the cholesteric liquid crystal layer alternates between regions where the tilt increases and regions where the tilt decreases. [3] The reflective member for a head-up display system according to [1] or [2], wherein the maximum reflectance among reflectances measured at intervals of 10 nm over a wavelength range of 380 to 780 nm is 30% or more. [4] The reflective member for a head-up display system according to any one of [1] to [3], further comprising a retardation layer. [5] A head-up display system comprising: a projector including a light source; the reflective member for a head-up display system according to any one of [1] to [4], which is irradiated with projection light emitted from the projector; and a windshield glass which is irradiated with light reflected by the reflective member. [6] The head-up display system according to [5], wherein the windshield glass has a P-polarized reflective film.

[0008] According to the present invention, it is possible to provide a reflective member for a head-up display system that can suppress reflection of external light and has a wide eyebox range when incorporated into the head-up display system. Also, the present invention can provide a head-up display system.

[0009] FIG. 1 is a diagram showing an example of a head-up display system. FIG. 2 is a cross-sectional schematic diagram showing the state of a cholesteric liquid crystal phase observed with a scanning electron microscope. FIG. 3 is an enlarged cross-sectional schematic diagram showing the state of a cholesteric liquid crystal phase in the XZ plane observed with a scanning electron microscope. FIG. 4 is a diagram showing an example of a windshield glass. FIG. 5 is a cross-sectional schematic diagram of a second composition layer satisfying condition 1. －１ ) × concentration (mass%) and light irradiation dose (mJ / cm ２ ) in a system in which chiral agent A and chiral agent B are used in combination. －１ ) and light irradiation dose (mJ / cm ２ ) for each of chiral agent A and chiral agent B. －１ 1 is a schematic diagram of a graph plotting the relationship between the concentration (mass%) and the temperature (°C).

[0010] The reflective member for a head-up display system and the head-up display system of the present invention will be described in detail below based on preferred embodiments shown in the drawings. Note that the drawings described below are merely illustrative for explaining the present invention, and the present invention is not limited to the drawings shown below. Note that in the following, the range of values ​​indicated by "to" includes the values ​​written on both sides. For example, ε １ is the number α １ ~Number β １ That is, ε １ The range of α １ and the number β １ The range includes α １ ≦ε １ ≦β １Unless otherwise specified, angles such as "angles expressed by specific numerical values," "parallel," "horizontal," "vertical," and "orthogonal" include a generally acceptable error range in the relevant technical field. Specifically, this means that the angle is within a range of ±10° or less from the exact angle, and the error from the exact angle is preferably 7° or less, and more preferably 5° or less. Furthermore, "the same" includes a generally acceptable error range in the relevant technical field, and "all over the surface" and the like also include a generally acceptable error range in the relevant technical field.

[0011] Unless otherwise specified, the term "light" refers to visible light and natural light (unpolarized). Visible light is electromagnetic light with wavelengths visible to the human eye, and typically refers to light in the wavelength range of 380 to 780 nm. Invisible light is light in the wavelength range of less than 380 nm or greater than 780 nm. Furthermore, although not limited thereto, within visible light, light in the wavelength range of 420 to 490 nm is blue (B) light, light in the wavelength range of 495 to 570 nm is green (G) light, and light in the wavelength range of 620 to 750 nm is red (R) light.

[0012] "Visible light transmittance" refers to the A-light source visible light transmittance defined in JIS (Japanese Industrial Standards) R 3212:2015 (Test Methods for Automotive Safety Glass). That is, the transmittance is determined by measuring the transmittance at each wavelength in the range of 380 to 780 nm using a spectrophotometer with an A-light source, and multiplying the transmittance at each wavelength by a weighting coefficient obtained from the wavelength distribution and wavelength interval of the CIE (Commission Internationale de l'Eclairage) photopic standard relative luminosity factor, and calculating a weighted average. When simply referring to "reflected light" or "transmitted light," this term is used to include scattered light and diffracted light.

[0013] P-polarized light refers to polarized light that vibrates in a direction parallel to the plane of incidence of light, while S-polarized light refers to polarized light that vibrates in a direction perpendicular to the plane of incidence of light. The plane of incidence is perpendicular to the reflecting surface (such as the surface of a windshield glass) and refers to the plane that contains the incident and reflected light rays. In P-polarized light, the vibration plane of the electric field vector is parallel to the plane of incidence, while in S-polarized light, the vibration plane of the electric field vector is perpendicular to the plane of incidence.

[0014] The in-plane retardation (in-plane phase difference) is a value measured using an AxoScan manufactured by Axometrics. Unless otherwise specified, the measurement wavelength is 550 nm. The in-plane retardation is measured by irradiating light with a wavelength within the visible light wavelength range in the normal direction of the film (normal direction of the surface of the retardation layer).

[0015] "Projection image" means an image based on the projection of light from the projector being used, rather than the surrounding scenery such as the view ahead. A projection image is perceived by an observer as a virtual image that appears to appear beyond the windshield glass. "Screen image" means an image displayed on the projector's drawing device, or an image drawn by the drawing device on an intermediate image screen or the like. A projection image is a virtual image, whereas a screen image is a real image. Both the image and the projection image may be a monochromatic image, a multi-color image with two or more colors, or a full-color image.

[0016] A feature of the present invention is that a specific reflecting member is used, as will be described later.

[0017] [Head-up display system] Figure 1 shows an example of a head-up display system of the present invention. The head-up display system 10 of the present invention shown in Figure 1 is an in-vehicle head-up display system, and includes a projector 12 for the head-up display system, a windshield glass 14, and a shielding layer 16. A reflective member for the head-up display is disposed between the projector 12 and the windshield glass 14 (on the optical path). Note that the drawings in this invention are schematic diagrams, and the thickness relationships and positional relationships of the various layers do not necessarily correspond to the actual ones. The same applies to the following drawings.

[0018] Hereinafter, the projector 12 for the head-up display system will also be simply referred to as the "projector 12."

[0019] In the head-up display system 10 illustrated in Fig. 1, light emitted from a light source 20 is converted into a real image by a reflecting member 22 and reflected along a predetermined optical path, passes through a transparent window 32 provided in a dashboard 30, and is emitted as projected light, and is then projected onto the windshield glass 14 and observed by an observer OB. Note that, as with a normal head-up display system, in the example illustrated in Fig. 1, the observer OB observes the image projected onto the windshield glass 14 as a virtual image through the windshield glass 14.

[0020] Each component of the head-up display system 10 will be described in detail below. The reflecting member 22, which is a feature of the present invention, will be described in detail first.

[0021] <Reflecting Member> The reflecting member 22 has a cholesteric liquid crystal layer 24 and a support 26. When light emitted from the light source 20 reaches the reflecting member 22, it is turned into a real image (visible image) by the reflecting member 22 and reflected to a predetermined optical path.

[0022] The reflective member of the present invention is a reflective member for a head-up display system. Specifically, it is a reflective member for a head-up display system that is arranged (on the optical path) between the light source 20 and the windshield glass 14 in the head-up display system 10. In other words, the reflective member of the present invention is a member that is not arranged between the light source 20 and the windshield glass 14 and does not belong to either the light source 20 or the windshield glass 14. Note that it is sufficient for the cholesteric liquid crystal layer 24 to retain the optical properties of a cholesteric liquid crystal phase within the layer, and the liquid crystal compound in the layer does not need to exhibit liquid crystallinity.

[0023] FIG. 2 is a cross-sectional schematic diagram showing the state of the cholesteric liquid crystal phase observed with a scanning electron microscope (SEM) in a cross section perpendicular to the major surfaces 24A and 24B of the cholesteric liquid crystal layer 24. Hereinafter, the major surfaces 24A and 24B of the cholesteric liquid crystal layer 24 are referred to as the X-Y plane, and the cross section perpendicular to the X-Y plane is referred to as the X-Z plane. Note that FIG. 2 is a diagram relating to the X-Z plane. In the cross section (X-Z plane) perpendicular to the major surface 24A of the cholesteric liquid crystal layer 24 shown in FIG. 2, it is observed that light and dark lines consisting of light regions 27 and dark regions 28 form a striped pattern with a wavy structure (undulation structure). In other words, the alignment direction P1 of the light regions 27 and dark regions 28 derived from the cholesteric liquid crystal phase is tilted with respect to the major surfaces 24A and 24B of the cholesteric liquid crystal layer 24. Furthermore, the bright regions 27 and dark regions 28 derived from the cholesteric liquid crystal phase extend from the major surface 24A toward the major surface 24B of the cholesteric liquid crystal layer 24. Two repetitions of the bright regions 27 and dark regions 28 in the cholesteric liquid crystal layer 24 correspond to the helical pitch of the cholesteric liquid crystal phase. The wavy structure in the cholesteric liquid crystal layer 24 diffuses the light beam emitted from the light source 20, allowing the reflecting member 22 to form the light beam into a real image. The angle formed by the alignment direction P1 of the bright regions 27 and dark regions 28 derived from the cholesteric liquid crystal phase and the major surface 24A of the cholesteric liquid crystal layer 24 is not particularly limited, but is preferably 20 to 45°, and more preferably 20 to 30°.

[0024] FIG. 3 is an enlarged cross-sectional schematic diagram showing the state of the cholesteric liquid crystal phase in the X-Z plane observed with a scanning electron microscope. FIG. 3 is a partially enlarged view of the wavy structure formed by the light and dark regions 27 and 28 in FIG. 2 . As shown in FIG. 3 , the light and dark regions 27 and 28 form a wavy structure, and as a result, in the cholesteric liquid crystal layer 24, the angle between the helical axis of the cholesteric liquid crystal phase and the major surface 24A changes continuously within the plane. This point will be described in detail below. In the cholesteric liquid crystal layer 24, the helical axis varies depending on the position of the cholesteric liquid crystal 24. The helical axis extends in a direction perpendicular to the tangent line at the position on the dark region 28. In the dark region 28, convex regions C1 and concave regions C2 repeatedly appear from right to left in the plane of FIG. 4 . As shown in FIG. 3 , at a position to the right of the apex of the convex portion C1 of the dark portion 28, the helical axis S1 extends in a predetermined direction, and the angle between this helical axis S1 and the main surface 24A is defined as angle α1. Also, at a position near the apex of the convex portion C1, as shown in FIG. 3 , the helical axis S2 extends in a predetermined direction, and the angle between this helical axis S2 and the main surface 24A is defined as angle α2. Also, at a position to the left of the apex of the convex portion C1, as shown in FIG. 3 , the helical axis S3 extends in a predetermined direction, and the angle between this helical axis S3 and the main surface 24A is defined as angle α3. Comparing angles α1 and α3, the relationship of angle α1 > angle α2 > angle α3 holds, and the angle between the helical axis and the main surface decreases. Meanwhile, as one moves further toward the concave portion C2, the angle between the helical axis and the main surface gradually increases. As described above, in the dark portion 28 in the cholesteric liquid crystal layer 24, convex portions and concave portions repeatedly appear along the in-plane direction. Therefore, along the in-plane direction of the cholesteric liquid crystal layer 24, regions where the inclination of the helical axis of the cholesteric liquid crystal phase with respect to the major surface 24A of the cholesteric liquid crystal layer 24 increases and regions where it decreases repeatedly appear. In other words, the inclination of the helical axis of the cholesteric liquid crystal phase changes periodically in the in-plane direction. A cholesteric liquid crystal layer having such characteristics has excellent reflective diffusivity.

[0025] 3, it is sufficient that the inclination of the helical axis of the cholesteric liquid crystal phase changes in the in-plane direction in a cross section perpendicular to one of the main surfaces of the cholesteric liquid crystal layer. In particular, as described above, it is preferable that the cholesteric liquid crystal layer 24 has a region where the inclination of the helical axis of the cholesteric liquid crystal phase with respect to the main surface of the cholesteric liquid crystal layer alternates between an increasing region and a decreasing region along one in-plane direction of the cholesteric liquid crystal layer.

[0026] A reflective member including a cholesteric liquid crystal layer having the above-described properties exhibits the following characteristics. For example, in a head-up display system that projects an image from a display element onto a windshield, when external light such as sunlight enters the windshield from outside, the light is specularly reflected from the surface of the display element. This specularly reflected light travels the same optical path as the light emitted from the display element, resulting in poor visibility of the virtual image due to glare from the external light. On the other hand, when the reflective member of the present invention has an inclined structure, the external light is diffusely reflected by the reflective member in a direction different from the incident direction, suppressing specular reflection and thus suppressing glare from the external light. Furthermore, the reflective member can convert light emitted from a light source into a real image and reflect it, thereby serving as both a reflector and an intermediate image screen used in a head-up display. Therefore, when a reflective member is used, space can be saved, the optical path length of the projected light can be shortened, and the range of the eyebox can be expanded.

[0027] The cholesteric liquid crystal layer 24 is a layer that exhibits selective reflection characteristics for light in a predetermined wavelength range. The cholesteric liquid crystal layer 24 functions as a circularly polarized light selective reflection layer that selectively reflects either right-handed or left-handed circularly polarized light in the selective reflection wavelength range and transmits circularly polarized light of the other sense. In FIG. 1 , the reflective member 22 has only one cholesteric liquid crystal layer 24, but it may have two or more layers. When the reflective member has multiple cholesteric liquid crystal layers exhibiting the above characteristics, the senses of circularly polarized light reflected by the multiple cholesteric liquid crystal layers may be the same or opposite depending on the application. Furthermore, the center wavelengths of the selective reflections (described below) of each cholesteric liquid crystal layer may be the same or different depending on the application.

[0028] In this specification, the term "sense" in reference to circularly polarized light means right-handed or left-handed circularly polarized light. The sense of circularly polarized light is defined as follows: when viewed as if the light is traveling toward you, if the tip of the electric field vector rotates clockwise as time increases, it is right-handed circularly polarized light, and if it rotates counterclockwise, it is left-handed circularly polarized light. In this specification, the term "sense" is also used to refer to the twist direction of the helix of the cholesteric liquid crystal. When the twist direction (sense) of the helix of the cholesteric liquid crystal is right-handed, the cholesteric liquid crystal reflects right-handed circularly polarized light and transmits left-handed circularly polarized light; when the sense is left-handed, the cholesteric liquid crystal reflects left-handed circularly polarized light and transmits right-handed circularly polarized light.

[0029] The central wavelength λ of the selective reflection depends on the pitch P (= helical period) of the helical structure in the cholesteric liquid crystal phase and follows the relationship λ = n × P with the average refractive index n of the cholesteric liquid crystal layer. Here, the central wavelength λ of the selective reflection of the cholesteric liquid crystal layer refers to the wavelength at the center of gravity of the reflection peak of the circularly polarized light reflection spectrum measured from the normal direction of the cholesteric liquid crystal layer. As can be seen from the above formula, the central wavelength of the selective reflection can be adjusted by adjusting the pitch of the helical structure. The pitch of the cholesteric liquid crystal phase depends on the type of chiral agent or its concentration, so the desired pitch can be obtained by adjusting these. The helical sense and pitch can be measured using the methods described in "Introduction to Liquid Crystal Chemistry Experiments," edited by the Japanese Liquid Crystal Society, Sigma Publishing, 2007, p. 46, and "Liquid Crystal Handbook," Liquid Crystal Handbook Editorial Committee, Maruzen, p. 196.

[0030] The reflective member preferably has a cholesteric liquid crystal layer B having a central wavelength of selective reflection in the blue light wavelength range, a cholesteric liquid crystal layer G having a central wavelength of selective reflection in the green light wavelength range, and a cholesteric liquid crystal layer R having a central wavelength of selective reflection in the red light wavelength range, and more preferably has the cholesteric liquid crystal layer B, the cholesteric liquid crystal layer G, and the cholesteric liquid crystal layer R in this order from the incident light side. Note that it is preferable that the cholesteric liquid crystal layer B, the cholesteric liquid crystal layer G, and the cholesteric liquid crystal layer R are all layers corresponding to the cholesteric liquid crystal layer 24 described above.

[0031] The maximum reflectance of the cholesteric liquid crystal layer contained in the reflective member measured at every 10 nm wavelength in the wavelength range of 380 to 780 nm is preferably 15% or more, more preferably 30% or more, even more preferably 40% or more, and particularly preferably 49.9% or more. The upper limit is preferably 50% or less. Furthermore, the reflectance of the cholesteric liquid crystal layer at wavelengths of 445 nm, 520 nm, and 635 nm is preferably 15% or more, more preferably 30% or more, even more preferably 40% or more, and particularly preferably 49.9% or more. The upper limit is preferably 50% or less. The maximum reflectance refers to the highest reflectance when irradiated with unpolarized light at every 10 nm wavelength in the wavelength range of 380 to 780 nm. Furthermore, examples of methods for measuring the maximum reflectance include the measurement methods shown in the Examples section.

[0032] The thickness of the cholesteric liquid crystal layer is preferably 2.0 μm or more, more preferably 5.0 μm or more, even more preferably 10.0 μm or more, and particularly preferably 20.0 μm or more. The upper limit is preferably 50.0 μm or less. When the cholesteric liquid crystal layer has multiple cholesteric liquid crystal layers, the above thickness refers to the total thickness of the multiple cholesteric liquid crystal layers. The thickness of the cholesteric liquid crystal layer B is preferably 0.5 μm or more, more preferably 3.0 μm or more, and even more preferably 5.0 μm or more. The upper limit is preferably 20.0 μm or less. The thickness of the cholesteric liquid crystal layer G is preferably 0.5 μm or more, more preferably 3.5 μm or more, and even more preferably 6.0 μm or more. The upper limit is preferably 20.0 μm or less. The thickness of the cholesteric liquid crystal layer R is preferably 1.0 μm or more, more preferably 5.0 μm or more, and even more preferably 8.0 μm or more. The upper limit is preferably 20.0 μm or less.

[0033] The reflecting member 22 has a support 26. The support 26 is an optional member, and may not be included in the reflecting member 22. The type of the support 26 is not particularly limited, and examples thereof include a substrate, which will be described later.

[0034] The reflecting member 22 may include other components in addition to the components described above. For example, the reflecting member 22 may have a liquid crystal layer between the cholesteric liquid crystal layer 24 and the support 26, the liquid crystal layer having a surface on which a discotic liquid crystal compound is tilted (hereinafter also referred to as an "inclined alignment surface"). On at least one surface of the liquid crystal layer, the molecular axis of the discotic liquid crystal compound is tilted with respect to the surface. In other words, on at least one surface of the liquid crystal layer, the discotic liquid crystal compound is aligned such that its molecular axis is tilted with respect to the surface. The liquid crystal layer is formed by step 1-1, which will be described later.

[0035] The reflective member may also include a pressure-sensitive adhesive layer.

[0036] <Projector> The projector 12 has a light source 20. The light source 20 emits a light beam modulated according to a projection image. There are no particular limitations on the type of light source 20, and a light source used for image formation is preferable. Examples of the light source 20 include LEDs (Light Emitting Diodes) such as light emitting diodes and organic light emitting diodes (OLEDs), discharge tubes, and laser light sources.

[0037] The head-up display system 10 may include a polarizing plate between the light source 20 and the reflecting member 22. The polarizing plate converts an incident light beam into P-polarized light (p-linearly polarized light). The type of polarizing plate is not particularly limited, and examples thereof include ordinary linear polarizing plates (linear polarizers). Examples of polarizing plates include polarizing plates formed by laminating thin films with different refractive index anisotropies. Examples of polarizing plates formed by laminating thin films with different refractive index anisotropies include the polarizing plates described in JP-A-9-506837. Specifically, polarizing plates can be formed using a wide variety of materials by processing them under conditions selected to obtain a refractive index relationship. Commercially available polarizing plates formed by laminating thin films with different refractive index anisotropies may be used. Examples of commercially available polarizing plates include DBEF (manufactured by 3M) and APF (Advanced Polarizing Film). Furthermore, common linear polarizing plates, such as absorptive polarizing plates containing iodine compounds and reflective polarizing plates such as wire grids, can also be used.

[0038] The head-up display system 10 may have an optical deflector between the light source 20 and the reflecting member 22. In other words, the optical deflector may be provided between the light beam emitted from the light source 20 and the reflecting member 22. Examples of the optical deflector include a normal optical deflector that can secondarily scan the light beam. Specific examples include a galvanometer mirror (galvanometer mirror), a combination of a galvanometer mirror and a polygon mirror, and a microelectromechanical system (MEMS), with MEMS being preferred.

[0039] A retardation layer may be disposed between the light source 20 and the reflecting member 22. When linearly polarized light (e.g., p-polarized light) is emitted from the light source 20, the polarization state changes as the light passes through the retardation layer, and the light is more likely to be reflected by the reflecting member 22. When the retardation layer converts linearly polarized light into circularly polarized light, the retardation layer is preferably configured to provide an in-plane retardation of λ / 4, and may also be configured to provide an in-plane retardation of 3λ / 4. The retardation layer may be disposed such that the angle of its slow axis is oriented to convert incident linearly polarized light into circularly polarized light.

[0040] In this case, the retardation layer preferably has an in-plane retardation in the range of 100 to 450 nm at a wavelength of 550 nm, more preferably in the range of 120 to 200 nm or 300 to 400 nm.

[0041] The type of retardation layer is not particularly limited and can be appropriately selected according to the purpose.For example, the retardation layer can be a stretched polycarbonate film, a stretched norbornene polymer film, a transparent film containing and oriented inorganic particles having birefringence such as strontium carbonate, a thin film obtained by obliquely depositing an inorganic dielectric on a support, a film in which a polymerizable liquid crystal compound is uniaxially aligned and fixed, and a film in which a liquid crystal compound is uniaxially aligned and fixed.

[0042] The thickness of the retardation layer is not particularly limited, but is preferably from 0.2 to 300 μm, more preferably from 0.5 to 150 μm, and even more preferably from 1.0 to 80 μm.

[0043] <Windshield Glass> The windshield glass 14 refers to the window glass and windshield glass of vehicles such as cars and trains, airplanes, ships, motorcycles, and playground equipment. The windshield glass 14 is preferably used as the windshield and windshield glass located in front of the vehicle in the traveling direction.

[0044] An example of a windshield glass is shown in Figure 4. The windshield glass 14 shown in Figure 4 has, in this order, a first glass plate 50, an intermediate film 52, a reflective film 54, a heat seal layer 56, and a second glass plate 58. In Figure 4, the reflective film 54 has, in this order from the first glass plate 50 side, a polarization conversion layer 60, a selective reflection layer 62, a retardation layer 64, and a transparent substrate 66. The reflective film 54 may be either a P-polarized light reflective film or an S-polarized light reflective film, with a P-polarized light reflective film being preferred.

[0045] When the windshield glass 14 is used in a vehicle, curved glass is often used as the first glass sheet 50 and the second glass sheet 58. In this case, if the first glass sheet 50 is located on the inside of the vehicle and the second glass sheet 58 is located on the outside of the vehicle, the first glass sheet 50 is arranged with its convex side facing the second glass sheet 58, and the second glass sheet 58 is arranged with its concave side facing the first glass sheet 50.

[0046] The visible light transmittance of the windshield glass 14 is not particularly limited, but a higher value is preferable. The visible light transmittance of the windshield glass 14 is preferably 70% or more, more preferably greater than 70%, even more preferably 75% or more, and particularly preferably 80% or more. The above-mentioned visible light transmittance is preferably satisfied at all positions on the windshield glass 14, and particularly preferably at the position where the reflective film 54 is present.

[0047] (First Glass Sheet and Second Glass Sheet) Glass sheets generally used for windshield glass can be used for the glass sheets such as the first glass sheet 50 and the second glass sheet 58. For example, glass sheets having a visible light transmittance of 80% or less, such as 73% or 76%, such as green glass with high heat insulation properties may be used.

[0048] The thickness of the first glass plate 50 and the second glass plate 58 is not particularly limited, but may be 0.5 to 5.0 mm, preferably 1.0 to 3.0 mm, and more preferably 2.0 to 2.3 mm. The materials or thicknesses of the first glass plate 50 and the second glass plate 58 may be the same or different.

[0049] (Interlayer Film) The interlayer film 52 prevents glass from penetrating into the vehicle interior and scattering in the event of an accident. In the example shown in FIG. 4 , the interlayer film 52 bonds the reflective film 54 and the first glass plate 50 together.

[0050] Any known interlayer film can be used as the interlayer film 52 (interlayer film sheet). For example, a resin film containing a resin selected from the group consisting of polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer, and chlorine-containing resin can be used. The above-mentioned resin is preferably the main component of the interlayer film. Here, the term "main component" refers to a component that accounts for 50% or more by mass of the interlayer film.

[0051] Of the above resins, polyvinyl butyral or ethylene-vinyl acetate copolymer is preferred, and polyvinyl butyral is more preferred. The resin is preferably a synthetic resin. Polyvinyl butyral is obtained by acetalizing polyvinyl alcohol with butylaldehyde. The degree of acetalization of the above polyvinyl butyral is preferably 40 to 85%, more preferably 60 to 75%.

[0052] The thickness of the intermediate film 52 is not particularly limited, and may be set in accordance with the forming material, etc., in the same manner as the intermediate film of a known windshield glass.

[0053] (Heat Seal Layer) The heat seal layer (adhesive layer) 56 is not particularly limited and may be, for example, a layer made of a coating type adhesive. In the example shown in Fig. 4, the reflective film 54 is attached to the second glass plate 58 by the heat seal layer 56. Note that although the embodiment in Fig. 4 shows a heat seal layer, the reflective film may be attached directly to the second glass plate.

[0054] The type of heat seal layer 56 is not particularly limited, and any known adhesive made of various types of coating type adhesive can be used as long as it can ensure the transparency required for the windshield glass 14 and can bond the reflective film 54 and the second glass plate 58 with the required adhesive strength. The heat seal layer 56 may be made of the same material as the interlayer 52, such as PVB.

[0055] The heat seal layer 56 may be formed from an adhesive, which may be a hot melt type, a heat curing type, a light curing type, a reaction curing type, or a pressure sensitive adhesive type that does not require curing, depending on the curing method.

[0056] The heat seal layer 56 may be formed using a highly transparent adhesive transfer tape (OCA tape). As the highly transparent adhesive transfer tape, a commercially available product for image display devices, particularly a commercially available product for the surface of the image display unit of an image display device, may be used. Examples of commercially available products include adhesive sheets (PD-S1, etc.) manufactured by Panac Corporation and adhesive sheets from the MHM series manufactured by Nichiei Kako Co., Ltd.

[0057] (Polarization Conversion Layer) The polarization conversion layer 60 exhibits optical rotation and birefringence for visible light and converts the polarization state of incident light. The polarization conversion layer 60 converts projected P-polarized light (linearly polarized light) into circularly polarized light reflected by the cholesteric liquid crystal layer of the selective reflection layer 62. The polarization conversion layer 60 is preferably a layer in which a helical orientation structure of a liquid crystal compound is fixed. In particular, the polarization conversion layer 60 is preferably a layer in which a helical orientation structure of a liquid crystal compound is fixed, and the pitch number x of the helical orientation structure and the film thickness y (unit: μm) of the polarization conversion layer preferably satisfy all of the following relational expressions (a) to (c): 0.1≦x≦1.0 (equation (a)); 0.5≦y≦3.0 (equation (b)); and 3000≦(1560×y) / x≦50000 (equation (c)). Note that one pitch of the helical structure of the liquid crystal compound is one turn of the helix of the liquid crystal compound. That is, the pitch number is defined as 1 when the director of the helically aligned liquid crystal compound (the long axis direction in the case of a rod-like liquid crystal) rotates 360°.

[0058] When the polarization conversion layer 60 has a helical structure of a liquid crystal compound, it exhibits optical rotation and birefringence for visible light, which has a wavelength shorter than the reflection peak wavelength in the infrared range. Therefore, it is possible to control polarization in the visible range. By setting the pitch number x of the helical orientation structure of the polarization conversion layer 60 and the film thickness y of the polarization conversion layer 60 within the above ranges, it is possible to provide the polarization conversion layer 60 with the function of optically compensating for visible light, or the function of converting linearly polarized light (P-polarized light) incident on the reflective film 54 into circularly polarized light.

[0059] The liquid crystal compound has a helical structure that satisfies the relational expressions (a) to (c), so that the polarization conversion layer 60 exhibits optical rotation and birefringence for visible light. In particular, by setting the pitch P of the helical structure of the polarization conversion layer 60 to a length that corresponds to the pitch P of the cholesteric liquid crystal layer whose selective reflection center wavelength is in the long-wavelength infrared region, the polarization conversion layer 60 exhibits high optical rotation and birefringence for short-wavelength visible light.

[0060] The pitch number x of the spiral structure of the polarization conversion layer 60 is preferably 0.1 to 0.8, and the film thickness y is preferably 0.6 to 2.6 μm. Also, "(1560×y) / x" is preferably 5000 to 13000.

[0061] The polarization conversion layer 60 can basically be formed in the same manner as a known cholesteric liquid crystal layer.

[0062] A layer in which the helical orientation structure (helical structure) of a liquid crystal compound is fixed is a so-called cholesteric liquid crystal layer, meaning a layer in which a cholesteric liquid crystal phase is fixed. A cholesteric liquid crystal layer may be any layer in which the orientation of a liquid crystal compound in a cholesteric liquid crystal phase is maintained. A cholesteric liquid crystal layer is typically a layer in which a polymerizable liquid crystal compound is oriented in a cholesteric liquid crystal phase, polymerized and cured by ultraviolet irradiation, heating, or the like, to form a layer with no fluidity, and at the same time, changed to a state in which the orientation form does not change due to an external field or external force. It is sufficient for a cholesteric liquid crystal layer to retain the optical properties of the cholesteric liquid crystal phase, and the liquid crystal compound in the layer may no longer exhibit liquid crystallinity. For example, a polymerizable liquid crystal compound may be polymerized by a curing reaction and no longer have liquid crystallinity.

[0063] (Selective Reflection Layer) The selective reflection layer 62 has three cholesteric liquid crystal layers (68R, 68G, and 68B). The three cholesteric liquid crystal layers have different selective reflection center wavelengths. In the illustrated example, the selective reflection layer 62 has, in this order, a cholesteric liquid crystal layer 68R having a selective reflection center wavelength in the red wavelength region, a cholesteric liquid crystal layer 68G having a selective reflection center wavelength in the green wavelength region, and a cholesteric liquid crystal layer 68B having a selective reflection center wavelength in the blue wavelength region. In the illustrated example, each cholesteric liquid crystal layer is in direct contact with any of the other cholesteric liquid crystal layers.

[0064] The cholesteric liquid crystal layer is a layer in which liquid crystal compounds are fixed in a helical oriented state of a cholesteric liquid crystal phase, and reflects light with a selective reflection center wavelength corresponding to the pitch of the helical structure and transmits light in other wavelength ranges. The cholesteric liquid crystal layer also exhibits selective reflection for either left- or right-handed circularly polarized light at a specific wavelength.

[0065] In addition, in FIG. 4, the selective reflection layer 62 has a configuration including three cholesteric liquid crystal layers with different selective reflection center wavelengths, but this is not limited to this, and the selective reflection layer 62 may have one cholesteric liquid crystal layer, or two or four or more cholesteric liquid crystal layers.

[0066] The total thickness of the selective reflection layer 62 is preferably 0.4 to 2.0 μm, more preferably 0.6 to 1.8 μm, and even more preferably 0.8 to 1.4 μm.

[0067] (Retardation Layer) The retardation layer 64 imparts a phase difference (optical path difference) between two orthogonal polarization components to change the state of incident polarized light. When the retardation layer 64 is disposed on the exterior side of the vehicle and provides optical compensation, the front retardation of the retardation layer 64 may be a retardation that allows optical compensation. In this case, the front retardation of the retardation layer 64 at a wavelength of 550 nm is preferably 50 to 160 nm. Furthermore, when the direction corresponding to the vertically upward direction of the surface of the first glass plate 50 when the windshield glass 14 having the reflective film 54 is mounted on a vehicle is defined as 0°, the angle of the slow axis of the retardation layer 64 is preferably 10 to 50°, or -50 to -10°.

[0068] Furthermore, when the retardation layer 64 converts linearly polarized light into circularly polarized light, the retardation layer 64 is preferably configured to provide an in-plane retardation of λ / 4, or may be configured to provide an in-plane retardation of 3λ / 4. The retardation layer 64 may be disposed such that the angle of the slow axis thereof is oriented in a direction that converts incident linearly polarized light into circularly polarized light.

[0069] In this case, the in-plane retardation of the retardation layer 64 at a wavelength of 550 nm is preferably in the range of 100 to 450 nm, more preferably in the range of 120 to 200 nm or 300 to 400 nm.

[0070] The type of the retardation layer 64 is not particularly limited and can be appropriately selected depending on the purpose. Examples of the retardation layer 64 include a stretched polycarbonate film, a stretched norbornene-based polymer film, a transparent film containing and oriented inorganic particles having birefringence such as strontium carbonate, a thin film obtained by obliquely depositing an inorganic dielectric on a support, a film in which a polymerizable liquid crystal compound is uniaxially oriented and fixed in orientation, and a film in which a liquid crystal compound is uniaxially oriented and fixed in orientation.

[0071] The thickness of the retardation layer 64 is not particularly limited, but is preferably 0.2 to 300 μm, more preferably 0.5 to 150 μm, and even more preferably 1.0 to 80 μm.

[0072] (Transparent Substrate) The transparent substrate 66 can also be used as a substrate when forming the selective reflection layer 62. The transparent substrate 66 used for forming the selective reflection layer 62 may be a temporary support that is peeled off after the selective reflection layer 62 is formed.

[0073] The material of the transparent substrate 66 is not particularly limited, and examples thereof include polyesters such as polyethylene terephthalate (PET), polycarbonate, acrylic resins, epoxy resins, polyurethanes, polyamides, polyolefins, cellulose derivatives, and plastic films such as silicone.

[0074] The thickness of the transparent substrate 66 is preferably 5.0 to 1000 μm, more preferably 10 to 250 μm, and even more preferably 15 to 90 μm.

[0075] When the projected light is S-polarized, it is preferable to use a windshield glass 14 that includes a first glass plate 50 and a second glass plate 58, and further includes a λ / 2 plate disposed between the first glass plate and the second glass plate.

[0076] <Shielding Layer> The head-up display system 10 has a shielding layer 16. The head-up display system of the present invention does not necessarily have to have the shielding layer 16. Examples of the shielding layer 16 include a known black ceramic layer. The arrangement of the shielding layer 16 is not particularly limited and can be adjusted appropriately depending on the purpose.

[0077] [Method for Manufacturing Reflective Member] The method for manufacturing the reflective member is not particularly limited and may be a known manufacturing method. Specifically, a method may be used in which a predetermined liquid crystal layer is used as an alignment substrate for the cholesteric liquid crystal layer, and a liquid crystal composition containing a chiral dopant X whose helical twist power (HTP) changes upon light irradiation or a chiral dopant Y whose helical twist power changes with temperature. Examples of methods for manufacturing a reflective member include a method for manufacturing a reflective member having steps 1 and 2. Step 1: Using a first liquid crystal composition containing a discotic liquid crystal compound, a first liquid crystal layer is formed on the surface of a substrate, in which the molecular axis of the discotic liquid crystal compound is tilted with respect to the surface on at least one surface. Step 2: Using a second liquid crystal composition containing a liquid crystal compound, a second liquid crystal layer (the cholesteric liquid crystal layer of the present invention) is formed on the first liquid crystal layer. Furthermore, in order to obtain a desired cholesteric liquid crystal phase in the cholesteric liquid crystal layer of the reflective member, for example, a method may be used in which the type and content of the liquid crystal compound described below, and the type and content of the surfactant, etc., are adjusted.

[0078] <Step 1> Step 1 is a step of forming a first liquid phase layer using a first liquid crystal composition containing a discotic liquid crystal compound. On at least one surface of the first liquid crystal layer, the molecular axis of the discotic liquid crystal compound is tilted with respect to the surface. In the manufacturing method of the present invention, a second liquid crystal layer is formed on the tilted alignment surface of the first liquid crystal layer having a surface on which the discotic liquid crystal compound is tilted (hereinafter also referred to as the "tilted alignment surface").

[0079] A specific method for Step 1 is preferably a method including Step 1-1 and Step 1-2. When the discotic liquid crystal compound has a polymerizable group, Step 1 preferably includes a curing treatment of the first composition layer. Step 1-1: A step of forming a first composition layer on an alignment film of a substrate having an alignment film disposed on the surface thereof, using a first liquid crystal composition containing a discotic liquid crystal compound. Step 1-2: A step of orienting the discotic compound in the first composition layer.

[0080] (Substrate) The substrate is a plate that supports the first composition layer described below. A transparent substrate is preferred as the substrate. The transparent substrate refers to a substrate having a visible light transmittance of 60% or more, preferably 80% or more, and more preferably 90% or more. The material constituting the substrate is not particularly limited, and examples thereof include cellulose-based polymers, polycarbonate-based polymers, polyester-based polymers, (meth)acrylic polymers, styrene-based polymers, polyolefin-based polymers, vinyl chloride-based polymers, amide-based polymers, imide-based polymers, sulfone-based polymers, polyethersulfone-based polymers, and polyetheretherketone-based polymers. The substrate may contain various additives such as UV (ultraviolet) absorbers, matting agent particles, plasticizers, anti-degradants, and release agents.

[0081] The thickness of the substrate is preferably 10 to 200 μm, more preferably 20 to 100 μm, from the viewpoint of thinning and ease of handling. The thickness is intended to be an average thickness, and is obtained by measuring the thickness at any five points on the substrate and calculating the arithmetic average thereof.

[0082] The alignment film is not particularly limited as long as it can align the discotic liquid crystal compound in a predetermined direction. The alignment film may be either a rubbed alignment film or a photo-aligned film. Examples of the rubbed alignment film include a rubbed alignment film having a pretilt angle, and a polyvinyl alcohol alignment film or a polyimide alignment film having a pretilt angle are preferred.

[0083] (First Liquid Crystal Composition) —Discotic Liquid Crystal Compound— The first liquid crystal composition contains a discotic liquid crystal compound. Examples of the discotic liquid crystal compound include known discotic liquid crystal compounds, and discotic liquid crystal compounds having a triphenylene skeleton are preferred. The discotic liquid crystal compound may have a polymerizable group. The type of polymerizable group is not particularly limited, and a functional group capable of undergoing an addition polymerization reaction is preferred, and a polymerizable ethylenically unsaturated group or a ring-polymerizable group is more preferred. Specifically, an acryloyl group, a methacryloyl group, a vinyl group, a styryl group, an allyl group, an epoxy group, or an oxetane group is preferred, and an acryloyl group or a methacryloyl group is more preferred.

[0084] Polymerization Initiator The first liquid crystal composition may contain a polymerization initiator. In particular, when the discotic liquid crystal compound has a polymerizable group, the first liquid crystal composition preferably contains a polymerization initiator. The polymerization initiator is preferably a photopolymerization initiator. Examples of the photopolymerization initiator include α-carbonyl compounds (U.S. Pat. Nos. 2,367,661 and 2,367,670), acyloin ethers (U.S. Pat. No. 2,448,828), α-hydrocarbon-substituted aromatic acyloin compounds (U.S. Pat. No. 2,722,512), polynuclear quinone compounds (U.S. Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketones (U.S. Pat. No. 3,549,367), acridine and phenazine compounds (Japanese Patent Laid-Open No. 60-105667, U.S. Pat. No. 4,239,850), and oxadiazole compounds (U.S. Pat. No. 4,212,970).

[0085] -Surfactant- The first liquid crystal composition may contain a surfactant that may be unevenly distributed on the substrate-side surface and / or the surface opposite to the substrate of the first liquid crystal layer. When the first liquid crystal composition contains a surfactant, the discotic compound is more likely to be aligned at a desired tilt angle. Examples of surfactants include onium salt compounds (JP 2012-208397 A), boronic acid compounds (JP 2013-054201 A), perfluoroalkyl compounds (Japanese Patent No. 4592225, Ftergent by Neos, etc.), and polymers containing these functional groups.

[0086] —Other Additives— The first liquid crystal composition may contain other additives, such as a solvent such as water or an organic solvent, an antioxidant, an ultraviolet absorber, a sensitizer, a stabilizer, a plasticizer, a chain transfer agent, a polymerization inhibitor, an antifoaming agent, a leveling agent, a thickener, a flame retardant, a surfactant, a dispersant, and a coloring material such as a dye or a pigment.

[0087] <Procedure of Step 1-1> In Step 1-1, the step of forming a first liquid crystal layer on an alignment film is preferably a step of forming a first composition layer of the first liquid crystal composition described above on the alignment film. The coating method is not particularly limited, and examples thereof include wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating. If necessary, a treatment for drying the coated film of the first liquid crystal composition may be carried out.

[0088] <Procedure of Step 1-2> Step 1-2 is preferably a step of heating the coating film to align the discotic compound in the first composition layer. Preferred heating conditions include heating the composition layer at 40 to 150°C (preferably 60 to 130°C) for 0.5 to 5 minutes (preferably 0.5 to 2 minutes). When heating the first composition layer, it is preferable to heat the first composition layer at a temperature lower than the temperature at which the liquid crystal compound becomes isotropic (Iso).

[0089] <Curing Treatment> When the discotic liquid crystal compound has a polymerizable group, it is preferable to perform a curing treatment on the first liquid crystal layer. The method of the curing treatment is not particularly limited, and examples thereof include photocuring treatment and heat curing treatment. Photoirradiation treatment is preferred, and ultraviolet irradiation treatment is more preferred. For ultraviolet irradiation, a light source such as an ultraviolet lamp is used. The amount of ultraviolet irradiation energy is not particularly limited, but is preferably 100 to 800 mJ / cm. ２ The time for irradiating with ultraviolet light may be appropriately determined from the viewpoints of both sufficient strength of the resulting layer and productivity.

[0090] In the inclined alignment plane of the first liquid crystal layer, the average tilt angle (average tilt angle) of the discotic liquid crystal compound with respect to the surface of the first liquid crystal layer is preferably 20 to 90°, more preferably 20 to 80°, even more preferably 30 to 80°, and particularly preferably 30 to 65°. The average tilt angle is the arithmetic mean of angles measured between the molecular axis of the discotic liquid crystal compound and the surface of the first liquid crystal layer at any five or more positions during polarizing microscope observation of the cross section of the first liquid crystal layer. The average tilt angle of the discotic liquid crystal compound with respect to the surface of the first liquid crystal layer in the inclined alignment plane of the first liquid crystal layer can be measured by polarizing microscope observation of the cross section of the first liquid crystal layer.

[0091] <Step 2> Step 2 is a step of forming a second liquid crystal layer (cholesteric liquid crystal layer) on the first liquid crystal layer using a second liquid crystal composition containing a liquid crystal compound.

[0092] Step 2 preferably includes the following steps 2-1 and 2-2: Step 2-1: forming a second composition layer on the first liquid crystal layer using a second liquid crystal composition containing a liquid crystal compound, the second composition layer satisfying condition 1 or condition 2; Condition 1: at least a part of the liquid crystal compound in the second composition layer is tilted relative to the surface of the second composition layer; Condition 2: the liquid crystal compound in the second composition layer is oriented such that the tilt angle of the liquid crystal compound changes continuously along the thickness direction; Step 2-2: forming a second liquid crystal layer (cholesteric liquid crystal layer) by performing a treatment to cholesterically align the liquid crystal compound in the second composition layer.

[0093] <Action Mechanism of Step 2-1> First, Fig. 5 shows a cross-sectional schematic diagram of the second composition layer obtained by step 2-1 and satisfying condition 1. The liquid crystal compound 42 shown in Fig. 5 is a rod-like liquid crystal compound.

[0094] As shown in Fig. 5, the second composition layer 100 is formed on the first liquid crystal layer 102. The first liquid crystal layer 102 has, on the surface in contact with the second composition layer 100, an inclined alignment surface 102a in which the molecular axis of the discotic liquid crystal compound is inclined with respect to the surface of the first liquid crystal layer 102. The first liquid crystal layer 102 and the inclined alignment surface 102a will be described later. As shown in Fig. 5, in the second composition layer 100 disposed on the inclined alignment surface 102a of the first liquid crystal layer 102, the liquid crystal compound 42 is loosely regulated in alignment by the inclined alignment surface 102a, and is aligned so as to be inclined with respect to the inclined alignment surface 102a. In other words, in the second composition layer 100, the liquid crystal compound 42 is aligned so that the molecular axis L of the liquid crystal compound 42 is inclined with respect to the inclined alignment surface 102a. １ is at a predetermined angle θ with respect to the surface of the second composition layer 100 １０ The molecules are oriented in a certain direction (uniaxial direction) so that:

[0095] In addition, the composition layer obtained by step 2-1 that satisfies condition 1 only needs to have a part of the liquid crystal compound 42 tilted, and the liquid crystal compound 42 has a molecular axis L oriented with respect to the surface of the composition layer 100 on at least one of the surface of the second composition layer 100 on the tilted alignment surface 102 a side (corresponding to region A in FIG. 5 ) and the surface of the second composition layer 100 opposite to the tilted alignment surface 102 a side (corresponding to region B in FIG. 5 ). １ is the given angle θ １０ In at least one of the regions A and B, the liquid crystal compound 42 is preferably aligned such that the molecular axis L １ is the given angle θ １０ If the liquid crystal compound 42 is oriented so as to be in a cholesteric liquid crystal phase state in the subsequent step 2-2, the alignment control force based on the oriented liquid crystal compound 42 in region A and / or region B can induce cholesteric alignment of the liquid crystal compound 42 in other regions.

[0096] Although not shown, the second composition layer satisfying the above-mentioned condition 2 corresponds to the first liquid crystal layer 102 shown in Fig. 5 in which the liquid crystal compound 42 is hybrid-aligned with respect to the surface of the second composition layer 100. Specifically, the liquid crystal compound 42 has a tilt angle θ ２０(Molecular axis L relative to the surface of the second composition layer 100 １ The angle) is the thickness direction R of the second composition layer 100 １ The second composition layer that satisfies the condition 2 and is obtained by the step 2-1 may be obtained as long as a part of the liquid crystal compound 42 is hybrid-aligned.

[0097] Angle θ １０ and θ ２０ is not particularly limited as long as it is not 0° throughout the entire second composition layer, and the angle θ １０ and θ ２０ However, the angle θ may be 0°. １０ and θ ２０ is preferably 0 to 90°, more preferably 0 to 50°, and even more preferably 0 to 10°.

[0098] In terms of better reflective anisotropy of the cholesteric liquid crystal layer, the composition layer obtained in step 2-1 preferably satisfies condition 1 or condition 2, and more preferably satisfies condition 2.

[0099] <Action mechanism of step 2-2> After obtaining a second composition layer that satisfies condition 1 or condition 2 in step 2-1, the liquid crystal compound in the second composition layer is cholesterically aligned in step 2-2 to form a second liquid crystal layer (cholesteric liquid crystal layer of the present invention).

[0100] <Mechanism of Action of Second Liquid Crystal Composition> A production method capable of producing a desired second liquid crystal layer (cholesteric liquid crystal layer) includes a method using a second liquid crystal composition containing a chiral dopant X whose helical twisting power (HTP) changes upon light irradiation or a chiral dopant Y whose helical twisting power changes upon temperature change.

[0101] The helical twist power (HTP) of a chiral dopant is a factor indicating the helical alignment ability, which is expressed by the following formula (1A): HTP=1 / (helical pitch length (unit: μm)×concentration of chiral dopant in liquid crystal composition (mass %)) [μm －１] The length of the helical pitch refers to the length of the pitch P (= helical period) of the helical structure of the cholesteric liquid crystal phase, and can be measured by the method described on page 196 of Liquid Crystal Handbook (published by Maruzen Co., Ltd.). The HTP value is affected not only by the type of chiral agent, but also by the type of liquid crystal compound contained in the second composition. Therefore, for example, when a composition containing a specific chiral agent X and a liquid crystal compound A and a composition containing a specific chiral agent X and a liquid crystal compound B different from liquid crystal compound A are prepared and the HTP of both are measured at the same temperature, the values ​​may differ. The helical twisting power (HTP) of a chiral agent can also be expressed by the following formula (1B). Formula (1B): HTP = (average refractive index of liquid crystal compound) / {(concentration of chiral agent in liquid crystal composition (mass%)) × (central reflection wavelength (nm))} [μm －１ When the liquid phase composition contains two or more chiral dopants, the "concentration of the chiral dopant in the liquid crystal composition" in the above formulas (1A) and (1B) corresponds to the sum of the concentrations of all the chiral dopants.

[0102] (Action Mechanism of Second Liquid Crystal Composition Containing Chiral Dopant X) Hereinafter, a method for forming a cholesteric liquid crystal layer using the second liquid crystal composition containing chiral dopant X will be described.

[0103] When a cholesteric liquid crystal layer is formed using a second liquid crystal composition containing chiral dopant X, a second composition layer satisfying condition 1 or 2 is formed in step 2-1, and then the second composition layer is subjected to a light irradiation treatment in step 2-2 to cholesterically align the liquid crystal compound in the second composition layer. That is, in step 2-2, the helical twisting power of chiral dopant X in the second composition layer is changed by the light irradiation treatment, thereby cholesterically aligning the liquid crystal compound in the second composition layer.

[0104] Here, when orienting the liquid crystal compound in the second composition layer to form a cholesteric liquid crystal phase, the helical twisting power that induces helical twisting of the liquid crystal compound is considered to roughly correspond to the weighted average helical twisting power of the chiral agent contained in the second composition layer. The weighted average helical twisting power referred to here is expressed by the following formula (1C), for example, when two types of chiral agents (chiral agent A and chiral agent B) are used in combination. Formula (1C) Weighted average helical twisting power (μm －１ ) = (helix-inducing power of chiral agent A (μm －１ ) × concentration (mass %) of chiral dopant A in the solid content of the second liquid crystal composition + helical twisting power of chiral dopant B (μm －１ ) × concentration (% by mass) of chiral dopant B in the solid content of the second liquid crystal composition) / (concentration (% by mass) of chiral dopant A in the solid content of the second liquid crystal composition + concentration (% by mass) of chiral dopant B in the solid content of the second liquid crystal composition) However, in the above formula (1C), when the helical direction of the chiral dopant is right-handed, the helical force is a positive value. On the other hand, when the helical direction of the chiral dopant is left-handed, the helical force is a negative value. That is, for example, when the helical force is 10 μm －１ In the case of the chiral agent, when the helical direction of the helix induced by the chiral agent is right-handed, the helix-inducing force is 10 μm －１ On the other hand, when the helical direction of the helix induced by the chiral agent is left-handed, the helical induction force is −10 μm －１ The weighted average helical twisting force (μm －１ ) can also be calculated from the above formula (1A) and the above formula (1B).

[0105] Below, we will discuss the weighted average helical twisting power when, for example, chiral agents A and B having the following properties are contained in the second composition layer. As shown in FIG. 6, the chiral agent A corresponds to chiral agent X, and is a chiral agent that has a leftward (-) helical twisting power and that reduces the helical twisting power upon light irradiation. Also, as shown in FIG. 6, the chiral agent B is a chiral agent that has a rightward (+) helical twisting power, which is the opposite direction to that of chiral agent A, and whose helical twisting power does not change upon light irradiation. Here, the "helical twisting power of chiral agent A (μm －１) × concentration of chiral agent A (mass%) and "helix-inducing power of chiral agent B (μm －１ ) × concentration of chiral dopant B (mass %) is equal to the value of the vertical axis. －１ ) × concentration (mass %) of chiral agent" is greater the further it is from zero. When the second composition layer contains the chiral agent A and the chiral agent B, the helical twisting power of the liquid crystal compound is equal to the weighted average helical twisting power of the chiral agent A and the chiral agent B. As a result, in a system using the chiral agent A and the chiral agent B in combination, as shown in Figure 7, it is considered that the helical twisting power of the liquid crystal compound increases in the direction (+) of the helix induced by the chiral agent B as the amount of irradiation light increases.

[0106] In the method for producing a cholesteric liquid crystal layer, the absolute value of the weighted average helical twisting power of the chiral agent in the second composition layer formed in step 2-1 is not particularly limited, but it is preferable that the absolute value be 0.0 to 1.9 μm in order to facilitate the formation of the second composition layer. －１ is preferred, and 0.0 to 1.5 μm －１ More preferably, 0.0 to 0.5 μm －１ is more preferably 0 μm －１ On the other hand, in the light irradiation treatment in step 2-2, the absolute value of the weighted average helical twisting power of the chiral agent in the second composition layer is not particularly limited as long as it is possible to cholesterically align the liquid crystal compound. －１ More than this is preferred, and 10.0 to 200.0 μm －１ More preferably, 20.0 to 200.0 μm －１ is more preferable. That is, in step 2-1, the helical twisting power of the chiral dopant X in the second composition layer is canceled out to approximately zero, thereby aligning the liquid crystal compound in the second composition layer to form an oblique alignment or a hybrid alignment. Next, the light irradiation treatment in step 2-2 is used as an opportunity to change the helical twisting power of the chiral dopant X and increase the weighted average helical twisting power of the chiral dopant in the second composition layer in either the rightward (+) or leftward (−) direction, thereby obtaining a cholesteric liquid crystal layer (e.g., cholesteric liquid crystal layer 22).

[0107] (Action mechanism of second liquid crystal composition containing chiral dopant Y) Next, a method for forming a cholesteric liquid crystal layer using a second liquid crystal composition containing chiral dopant Y will be described. When a cholesteric liquid crystal layer is formed using a second liquid crystal composition containing chiral dopant Y, a second composition layer satisfying condition 1 or condition 2 is formed in step 2-1, and then the second composition layer is subjected to a cooling treatment or a heat treatment in step 2-2 to cholesterically align the liquid crystal compound in the composition layer. That is, in step 2-2, the helical twisting force of the chiral dopant Y in the second composition layer is changed by the cooling treatment or the heat treatment, thereby cholesterically aligning the liquid crystal compound in the second composition layer.

[0108] As described above, when orienting the liquid crystal compound in the second composition layer to form a cholesteric liquid crystal phase, the helical twisting force that induces helical twist in the liquid crystal compound is considered to roughly correspond to the weighted average helical twisting force of the chiral agent contained in the second composition layer. The weighted average helical twisting force here is as described above. The mechanism of action of chiral agent Y will be explained below, taking as an example an embodiment in which the liquid crystal compound in the second composition layer is cholesterically aligned by performing a cooling treatment in step 2-2. First, the weighted average helical twisting force will be described below, for example, when the second composition layer contains chiral agents A and B having the following properties. As shown in Figure 8, the chiral agent A corresponds to chiral agent Y, and the temperature T １１ , and the temperature T at which the cooling treatment of step 2-2 is performed １２ The chiral agent B has a leftward (-) helical twisting power at a temperature T １１ The helical induction power of chiral agent A (μm －１ ) × concentration of chiral agent A (mass%) and "helix-inducing power of chiral agent B (μm －１) × concentration (mass %) of chiral agent B" is assumed to be equal. When the second composition layer contains the chiral agent A and the chiral agent B, the helical twisting power of the liquid crystal compound is equal to the weighted average helical twisting power of the chiral agent A and the chiral agent B. As a result, in a system using the chiral agent A and the chiral agent B in combination, it is considered that the helical twisting power of the liquid crystal compound increases in the lower temperature region in the direction of the helix induced by the chiral agent A (-).

[0109] In the method for producing a cholesteric liquid crystal layer, the absolute value of the weighted average helical twisting power of the chiral agent in the second composition layer is not particularly limited. However, when forming a second composition layer that satisfies condition 1 or condition 2 in step 2-1, it is preferable to use a value of 0.0 to 1.9 μm in order to facilitate the formation of the second composition layer. －１ is preferred, and 0.0 to 1.5 μm －１ More preferably, 0.0 to 0.5 μm －１ is more preferably 0 μm －１ On the other hand, the temperature T at which the cooling treatment in step 2-2 is carried out is particularly preferred. １２ In the second composition layer, the absolute value of the weighted average helical twisting power of the chiral agent is not particularly limited as long as it can cholesterically align the liquid crystal compound. －１ More than this is preferred, and 10.0 to 200.0 μm －１ More preferably, 20.0 to 200.0 μm －１ That is, the temperature T １１ In this case, the helical twisting force of the chiral dopant Y is canceled out to almost zero, so that the liquid crystal compound can be aligned in a tilted or hybrid alignment. １２ The helical twisting power of the chiral dopant Y is increased by the temperature change to 0°C, thereby increasing the weighted average helical twisting power of the chiral dopant in the composition layer in either the rightward (+) or leftward (−) direction, thereby obtaining a cholesteric liquid crystal layer (e.g., cholesteric liquid crystal layer 10).

[0110] <Procedure of Step 2> The procedure of Step 2 will be described in detail below. The procedure will be described separately for an embodiment using a second liquid crystal composition containing chiral dopant X and an embodiment using a second liquid crystal composition containing chiral dopant Y.

[0111] (Aspects Using a Second Liquid Crystal Composition Containing Chiral Dopant X) The procedure of Step 2 (hereinafter also referred to as "Step 2X") using a second liquid crystal composition containing chiral dopant X will be described below. Step 2X at least includes the following Steps 2X-1 and 2X-2. Step 2X-1: Using a second liquid crystal composition containing chiral dopant X and a liquid crystal compound, forming a second composition layer on a first liquid crystal layer, the second composition layer satisfying Condition 1 or Condition 2 below. Step 2X-2: Applying a light irradiation treatment to the second composition layer to cholesterically align the liquid crystal compound in the second composition layer, thereby forming a cholesteric liquid crystal layer. Condition 1: At least a portion of the liquid crystal compound in the second composition layer is tilted relative to the surface of the second composition layer. Condition 2: The liquid crystal compound is oriented such that the tilt angle of the liquid crystal compound in the second composition layer changes continuously along the thickness direction. When the liquid crystal compound has a polymerizable group, Step 2X preferably includes performing a curing treatment on the composition layer, as described below.

[0112] The materials used in each step and the procedures for each step will be described in detail below.

[0113] <<Step 2X-1>> Step 2X-1 is a step of forming a second composition layer that satisfies the above-mentioned condition 1 or 2 on a liquid crystal layer using a second liquid crystal composition (hereinafter also referred to as "composition X") containing a chiral dopant X and a liquid crystal compound. Hereinafter, composition X will be described in detail, and then the procedure of the step will be described in detail.

[0114] Composition X Composition X contains a liquid crystal compound and a chiral dopant X whose helical twisting power changes upon irradiation with light. Each component will be described below. As described above, the absolute value of the weighted average helical twisting power of the chiral dopant in the second composition layer obtained by Step 2X-1 is set to 0.0 to 1.9 μm in order to facilitate the formation of a composition layer. －１ is preferred, and 0.0 to 1.5 μm －１More preferably, 0.0 to 0.5 μm －１ is more preferably 0 μm －１ is particularly preferred. Therefore, when chiral dopant X has a helical twisting power exceeding the above-mentioned predetermined range before light irradiation treatment, composition X preferably contains a chiral dopant (hereinafter also referred to as "chiral dopant XA") that induces a helical twist in the opposite direction to that of chiral dopant X, and the helical twisting power of chiral dopant X is preferably offset to approximately zero during step 2X-1 (i.e., the weighted average helical twisting power of the chiral dopant in the composition layer obtained by step 2X-1 is set to be within the above-mentioned predetermined range). It is more preferred that chiral dopant XA be a compound whose helical twisting power does not change upon light irradiation treatment. Furthermore, when the second liquid crystal composition contains multiple chiral dopants X as the chiral agent, and the weighted average helical twisting power of the multiple chiral dopants X in the unexposed state is outside the above-mentioned predetermined range, "another chiral dopant XA that induces a helical twist in the opposite direction to that of the chiral dopant X" refers to a chiral dopant that induces a helical twist in the opposite direction to the weighted average helical twisting power of the multiple chiral dopants X. When a single chiral dopant X has no helical twisting power in the unexposed state but has the property of increasing its helical twisting power upon light irradiation, it is not necessary to use a chiral dopant XA in combination.

[0115] Liquid Crystal Compounds The type of liquid crystal compound is not particularly limited. Generally, liquid crystal compounds can be classified into rod-shaped types (rod-shaped liquid crystal compounds) and discotic types (discotic liquid crystal compounds, discotic liquid crystal compounds) based on their shape. Furthermore, the rod-shaped and discotic types are each divided into low-molecular-weight types and high-molecular-weight types. A high-molecular-weight compound generally refers to a compound with a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, by Masao Doi, page 2, Iwanami Shoten, 1992). In the present invention, any liquid crystal compound can be used. Furthermore, two or more liquid crystal compounds may be used in combination.

[0116] The liquid crystal compound may have a polymerizable group. The type of the polymerizable group is not particularly limited, and a functional group capable of addition polymerization reaction is preferred, and a polymerizable ethylenically unsaturated group or a ring-polymerizable group is more preferred. More specifically, the polymerizable group is preferably a (meth)acryloyl group, a vinyl group, a styryl group, an allyl group, an epoxy group, or an oxetane group, and more preferably a (meth)acryloyl group.

[0117] The liquid crystal compound is preferably a liquid crystal compound represented by the following formula (I).

[0118]

[0119] In the formula, A represents a phenylene group which may have a substituent or a trans-1,4-cyclohexylene group which may have a substituent, and at least one of As represents a trans-1,4-cyclohexylene group which may have a substituent; L represents a single bond or —CH ２ O-, -OCH ２ -, -(CH ２ ) ２ OC(=O)-, -C(=O)O(CH ２ ) ２ represents a linking group selected from the group consisting of -, -C(=O)O-, -OC(=O)-, -OC(=O)O-, -CH=N-N=CH-, -CH=CH-, -C≡C-, -NHC(=O)-, -C(=O)NH-, -CH=N-, -N=CH-, -CH=CH-C(=O)O-, and -OC(=O)-CH=CH-, m represents an integer of 3 to 12, Sp １ and Sp ２ are each independently a single bond, a linear or branched alkylene group having 1 to 20 carbon atoms, and a linear or branched alkylene group having 1 to 20 carbon atoms having one or more —CH ２ - is -O-, -S-, -NH-, -N(CH ３ Q represents a linking group selected from the group consisting of groups substituted with —C(═O)—, —OC(═O)—, or —C(═O)O—; １ and Q ２each independently represents a hydrogen atom or a polymerizable group selected from the group consisting of groups represented by the following formulas (Q-1) to (Q-5), １ and Q ２ represents a polymerizable group;

[0120]

[0121] A is a phenylene group which may have a substituent, or a trans-1,4-cyclohexylene group which may have a substituent. In this specification, when referring to a phenylene group, a 1,4-phenylene group is preferred. At least one of As is a trans-1,4-cyclohexylene group which may have a substituent. The m As may be the same or different.

[0122] m represents an integer of 3 to 12, preferably an integer of 3 to 9, more preferably an integer of 3 to 7, and even more preferably an integer of 3 to 5.

[0123] In formula (I), the substituent that the phenylene group and the trans-1,4-cyclohexylene group may have is not particularly limited, and examples thereof include a substituent selected from the group consisting of an alkyl group, a cycloalkyl group, an alkoxy group, an alkyl ether group, an amide group, an amino group, a halogen atom, and a group formed by combining two or more of the above-mentioned substituents. Examples of the substituent include the -C(=O)-X group described below. ３ -Sp ３ -Q ３ The phenylene group and the trans-1,4-cyclohexylene group may have 1 to 4 substituents. When the phenylene group and the trans-1,4-cyclohexylene group have two or more substituents, the two or more substituents may be the same or different.

[0124] In this specification, the alkyl group may be either linear or branched. The number of carbon atoms in the alkyl group is preferably 1 to 30, more preferably 1 to 10, and even more preferably 1 to 6. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a 1,1-dimethylpropyl group, an n-hexyl group, an isohexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group. The description of the alkyl group in the alkoxy group is the same as the description of the alkyl group above. Furthermore, in this specification, specific examples of the alkylene group include divalent groups obtained by removing any one hydrogen atom from each of the above examples of the alkyl group. Examples of halogen atoms include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0125] In this specification, the number of carbon atoms in the cycloalkyl group is preferably 3 or more, more preferably 5 or more, and is preferably 20 or less, more preferably 10 or less, still more preferably 8 or less, and particularly preferably 6 or less. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group.

[0126] Substituents that the phenylene group and trans-1,4-cyclohexylene group may have include an alkyl group, an alkoxy group, and —C(═O)—X ３ -Sp ３ -Q ３ Preferred are substituents selected from the group consisting of: ３ is a single bond, -O-, -S-, or -N(Sp ４ -Q ４ ) - or Q ３ and Sp ３ The nitrogen atom forming a ring structure with Sp is shown. ３ and Sp ４are each independently a single bond, a linear or branched alkylene group having 1 to 20 carbon atoms, and a linear or branched alkylene group having 1 to 20 carbon atoms having one or more —CH ２ - is -O-, -S-, -NH-, -N(CH ３ represents a linking group selected from the group consisting of groups substituted with —C(═O)—, —OC(═O)—, or —C(═O)O—. ３ and Q ４ are each independently a hydrogen atom, a cycloalkyl group, or a cycloalkyl group having one or more —CH ２ - is -O-, -S-, -NH-, -N(CH ３ )-, —C(═O)-, —OC(═O)-, or —C(═O)O-, or a polymerizable group selected from the group consisting of groups represented by formulae (Q-1) to (Q-5).

[0127] In the cycloalkyl group, one or more —CH ２ - is -O-, -S-, -NH-, -N(CH ３ Specific examples of the group substituted with —C(═O)—, —OC(═O)—, or —C(═O)O— include a tetrahydrofuranyl group, a pyrrolidinyl group, an imidazolidinyl group, a pyrazolidinyl group, a piperidyl group, a piperazinyl group, and a morpholinyl group. Of these, a tetrahydrofuranyl group is preferred, and a 2-tetrahydrofuranyl group is more preferred.

[0128] In formula (I), L is a single bond or —CH ２ O-, -OCH ２ -, -(CH ２ ) ２ OC(=O)-, -C(=O)O(CH ２ ) ２ L represents a linking group selected from the group consisting of -, -C(=O)O-, -OC(=O)-, -OC(=O)O-, -CH=CH-C(=O)O-, and -OC(=O)-CH=CH-. L is preferably -C(=O)O- or OC(=O)-. The m Ls may be the same or different.

[0129] Sp １ and Sp２ are each independently a single bond, a linear or branched alkylene group having 1 to 20 carbon atoms, and a linear or branched alkylene group having 1 to 20 carbon atoms having one or more —CH ２ - is -O-, -S-, -NH-, -N(CH ３ represents a linking group selected from the group consisting of groups substituted with —C(═O)—, —C(═O)—, —OC(═O)—, or —C(═O)O—. １ and Sp ２ are preferably each independently a linear alkylene group having 1 to 10 carbon atoms bonded to both terminals with linking groups selected from the group consisting of -O-, -OC(=O)-, and -C(=O)O-, or a linking group formed by combining one or more groups selected from the group consisting of -OC(=O)-, -C(=O)O-, -O-, and linear alkylene groups having 1 to 10 carbon atoms, and more preferably a linear alkylene group having 1 to 10 carbon atoms bonded to both terminals with -O-.

[0130] Q １ and Q ２ each independently represents a hydrogen atom or a polymerizable group selected from the group consisting of groups represented by the following formulas (Q-1) to (Q-5): １ and Q ２ represents a polymerizable group.

[0131]

[0132] The polymerizable group is preferably an acryloyl group (formula (Q-1)) or a methacryloyl group (formula (Q-2)).

[0133] As the liquid crystal compound, a compound represented by formula (VIII), particularly a polymerizable liquid crystal compound having two (meth)acrylate groups represented by the following formula (VIII) is preferred.

[0134]

[0135] In formula (VIII), A ２ and A ３ each independently represents an alkylene group having 2 to 18 carbon atoms, and one CH ２Or two or more non-adjacent channels ２ may be substituted with —O—; Z ５ represents —C(═O)—, —OC(═O)— or a single bond; Z ６ represents —C(═O)—, —C(═O)O— or a single bond; R ５ and R ６ each independently represents a hydrogen atom or a methyl group; ９ , L １０ , L １１ and L １２ each independently represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, an acyl group having 2 to 4 carbon atoms, a halogen atom, or a hydrogen atom; L ９ , L １０ , L １１ and L １２ At least one of these represents a group other than a hydrogen atom.

[0136] The compound represented by the above formula (VIII) is preferably a compound represented by the following formula (IX):

[0137]

[0138] In formula (IX), n2 and n3 each independently represent an integer of 3 to 6; １５ and R １６ each independently represents a hydrogen atom or a methyl group.

[0139] In formula (IX), n2 and n3 each independently represent an integer of 3 to 6, and it is preferable that n2 and n3 are 4. １５ and R １６ each independently represents a hydrogen atom or a methyl group, and the R １５ and R １６ Preferably, represents a hydrogen atom.

[0140] Such a liquid crystal compound can be produced by a known method. In order to obtain a composition layer that satisfies the above conditions 1 and 2, it is preferable to use a liquid crystal compound that has a large pretilt angle at the interface.

[0141] Specific examples of the liquid crystal compound include known compounds described in paragraphs 0118 to 0127 of WO 2022 / 00496.

[0142] Chiral agent X whose helical twisting power changes upon irradiation with light The chiral agent X is a compound that induces helical twist in a liquid crystal compound, and is not particularly limited as long as it is a chiral agent whose helical twisting power (HTP) changes upon irradiation with light. The chiral agent X may be liquid crystalline or non-liquid crystalline. The chiral agent X generally contains an asymmetric carbon atom. However, an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom can also be used as the chiral agent X. The chiral agent X may have a polymerizable group.

[0143] Examples of the chiral agent X include so-called photoreactive chiral agents. A photoreactive chiral agent has a chiral moiety and a photoreactive moiety that undergoes a structural change upon irradiation with light, and is, for example, a compound that significantly changes the twisting power of a liquid crystal compound depending on the amount of light irradiation. Examples of photoreactive moieties that undergo a structural change upon irradiation with light include photochromic compounds (Kingo Uchida, Masahiro Irie, Chemical Industry, Vol. 64, p. 640, 1999; Kingo Uchida, Masahiro Irie, Fine Chemical, Vol. 28(9), p. 15, 1999). The structural change refers to decomposition, addition reaction, isomerization, dimerization reaction, etc., that occur upon irradiation of the photoreactive moiety with light, and the structural change may be irreversible. Examples of the chiral moiety include the asymmetric carbons described in Hiroyuki Nodaira, Chemistry Review, No. 22, Chemistry of Liquid Crystals, p. 73, 1994.

[0144] Examples of the photoreactive chiral agent include the photoreactive chiral agents described in paragraphs 0044 to 0047 of JP-A No. 2001-159709, the optically active compounds described in paragraphs 0019 to 0043 of JP-A No. 2002-179669, the optically active compounds described in paragraphs 0020 to 0044 of JP-A No. 2002-179633, and the optically active compounds described in paragraphs 0016 to 0040 of JP-A No. 2002-179670. Examples of the optically active compounds include the optically active compounds described in paragraphs 0017 to 0050 of JP-A No. 2002-179668, the optically active compounds described in paragraphs 0018 to 0044 of JP-A No. 2002-180051, the optically active compounds described in paragraphs 0016 to 0055 of JP-A No. 2002-338575, and the optically active compounds described in paragraphs 0020 to 0049 of JP-A No. 2002-179682.

[0145] Among them, the chiral agent X is preferably a compound having at least one photoisomerization moiety. The photoisomerization moiety is preferably a cinnamoyl moiety, a chalcone moiety, an azobenzene moiety, a stilbene moiety, or a coumarin moiety, in that it has low visible light absorption, is easily photoisomerized, and has a large difference in helical twisting power before and after light irradiation, and a cinnamoyl moiety or a chalcone moiety is more preferred. The photoisomerization moiety corresponds to the photoreactive moiety that undergoes a structural change upon light irradiation as described above. Furthermore, the chiral agent X is preferably an isosorbide-based optically active compound, an isomannide-based optical compound, or a binaphthol-based optically active compound, in that it has a large difference in helical twisting power before and after light irradiation. In other words, the chiral agent X preferably has an isosorbide skeleton, an isomannide skeleton, or a binaphthol skeleton as the chiral moiety. As the chiral agent X, an isosorbide-based optically active compound or a binaphthol-based optically active compound is more preferred, and an isosorbide-based optically active compound is even more preferred, in that the difference in helical twisting power before and after light irradiation is greater.

[0146] The helical pitch of the cholesteric liquid crystal phase depends greatly on the type of chiral dopant X and its concentration, and a desired pitch can be obtained by adjusting these factors.

[0147] The chiral agent X may be used alone or in combination of two or more kinds.

[0148] The total content of the chiral dopant in composition X (total content of all chiral dopants in composition X) is preferably 2.0% by mass or more, and more preferably 3.0% by mass or more, relative to the total mass of the liquid crystal compound. In addition, the upper limit of the total content of the chiral dopants in composition X is preferably 15.0% by mass or less, and more preferably 12.0% by mass or less, relative to the total mass of the liquid crystal compound, from the viewpoint of suppressing haze in the cholesteric liquid crystal layer.

[0149] Optional Components Composition X may contain other components in addition to the liquid crystal compound and the chiral dopant X. Examples of the other components include the chiral dopant XA, a polymerization initiator that may be contained in the first liquid crystal composition, a surfactant, and other additives.

[0150] Chiral Agent XA The chiral agent XA is a compound that induces helical twist in a liquid crystal compound, and is preferably a chiral agent whose helical twist power (HTP) does not change upon irradiation with light. The chiral agent XA may be liquid crystalline or non-liquid crystalline. The chiral agent XA generally contains an asymmetric carbon atom. However, an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom can also be used as the chiral agent XA. The chiral agent XA may have a polymerizable group. Known chiral agents can be used as the chiral agent XA. The liquid crystal composition contains one type of chiral agent X alone, and the chiral agent X has a molecular weight within a predetermined range (for example, 0.0 to 1.9 μm) in a state before irradiation treatment. －１ ), the chiral dopant XA is preferably a chiral dopant that induces a helical twist in the opposite direction to that of the chiral dopant X. That is, for example, if the helical twist induced by the chiral dopant X is right-handed, the helical twist induced by the chiral dopant XA will be left-handed. Furthermore, when the liquid crystal composition contains multiple chiral dopants X as chiral agents and the weighted average helical twisting power of the liquid crystal composition before light irradiation exceeds the above-mentioned range, the chiral dopant XA is preferably a chiral dopant that induces a helical twist in the opposite direction to that of the weighted average helical twisting power.

[0151] <<Procedure of Step 2X-1>> Step 2X-1 preferably includes the following Step 2X-1-1 and Step 2X-1-2: Step 2X-1-1: A step of contacting composition X with the liquid crystal layer to form a coating film on the liquid crystal layer; and Step 2X-1-2: A step of heating the coating film to form a composition layer that satisfies the above condition 1 or 2.

[0152] Step 2X-1-1: Coating Film Formation Step In step 2X-1-1, first, the above-described composition X is applied onto the liquid crystal layer. The application method is not particularly limited, and examples thereof include wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating. Prior to application of composition X, the liquid crystal layer may be subjected to a known rubbing treatment. If necessary, after application of composition X, the coating film applied onto the liquid crystal layer may be dried. By performing the drying treatment, the solvent can be removed from the coating film.

[0153] The thickness of the coating film is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, and even more preferably 0.5 to 10 μm, in order to provide a cholesteric liquid crystal layer with better reflection anisotropy and haze.

[0154] Step 2X-1-2: Composition Layer Forming Step From the viewpoint of manufacturability, the liquid crystal phase transition temperature of composition X is preferably in the range of 10 to 250°C, more preferably in the range of 10 to 150°C. Preferred heating conditions include heating the composition layer at 40 to 100°C (preferably 60 to 100°C) for 0.5 to 5 minutes (preferably 0.5 to 2 minutes). When heating the composition layer, it is preferable not to heat it to a temperature at which the liquid crystal compound becomes isotropic (Iso). Heating the composition layer above the temperature at which the liquid crystal compound becomes isotropic increases defects in the tilted liquid crystal phase or hybrid aligned liquid crystal phase, which is not preferred.

[0155] By the above-mentioned step 2X-1-2, a composition layer satisfying the above-mentioned condition 1 or 2 can be obtained. In order to achieve tilted or hybrid alignment of the liquid crystal compound, it is effective to impart a pretilt angle to the interface, and specific examples of this method include the following: (1) Add to composition X an alignment control agent that is unevenly distributed at the air interface and / or the liquid crystal layer interface to control the alignment of the liquid crystal compound; (2) Add to composition X a liquid crystal compound that has a large pretilt angle at the interface.

[0156] <<Step 2X-2>> Step 2X-2 is a step of subjecting the composition layer obtained in Step 2X-1 to a light irradiation treatment to change the helical twisting power of the chiral dopant X and thereby cholesterically align the liquid crystal compound in the composition layer to form a cholesteric liquid crystal layer. Note that by dividing the light irradiation region into multiple domains and adjusting the amount of light irradiation for each domain, it is possible to form regions with further different helical pitches (regions with different selective reflection wavelengths).

[0157] The irradiation intensity of the light irradiation in step 2X-2 is not particularly limited and can be appropriately determined based on the helical twisting power of the chiral agent X. The irradiation intensity of the light irradiation in step 2X-2 is generally 0.1 to 200 mW / cm ２ The light irradiation time is not particularly limited, but may be appropriately determined from the viewpoints of both sufficient strength of the resulting layer and productivity. The temperature of the composition layer during light irradiation is, for example, 0 to 100°C, and preferably 10 to 60°C.

[0158] The light used for photoirradiation is not particularly limited as long as it is actinic ray or radiation that changes the helical twisting power of the chiral agent X, and includes, for example, the bright line spectrum of a mercury lamp, far ultraviolet light represented by an excimer laser, extreme ultraviolet light (EUV light: Extreme Ultraviolet), X-rays, ultraviolet light, and electron beam (EB), etc. Among these, ultraviolet light is preferred.

[0159] In the method for producing a cholesteric liquid crystal layer of the present invention, if the composition layer is exposed to wind, unevenness in the surface condition of the formed cholesteric liquid crystal layer may occur. In consideration of this point, in the method for producing a cholesteric liquid crystal layer of the present invention, it is preferable that the wind speed in the environment to which the composition layer is exposed is low throughout all steps of step 2X. Specifically, in the method for producing a cholesteric liquid crystal layer of the present invention, it is preferable that the wind speed in the environment to which the composition layer is exposed is 1 m / s or less throughout all steps of step 2X.

[0160] <<Curing Treatment>> When the liquid crystal compound has a polymerizable group, it is preferable to perform a curing treatment on the composition layer. Examples of the procedure for performing the curing treatment on the composition layer include (1) and (2) shown below.

[0161] (1) During step 2X-2, a curing treatment is carried out to fix the cholesteric alignment state, thereby forming a cholesteric liquid crystal layer in which the cholesteric alignment state is fixed (i.e., the curing treatment is carried out simultaneously with step 2X-2), or (1) after step 2X-2, step 3X is further included in which a curing treatment is carried out to fix the cholesteric alignment state, thereby forming a cholesteric liquid crystal layer in which the cholesteric alignment state is fixed.

[0162] In other words, the cholesteric liquid crystal layer obtained by performing a curing treatment corresponds to a layer in which a cholesteric liquid crystal phase is fixed. Here, the state in which a cholesteric liquid crystal phase is "fixed" is the most typical and preferred state in which the orientation of the liquid crystal compound in the cholesteric liquid crystal phase is maintained. However, this is not limited thereto. Specifically, it refers to a state in which the layer is non-fluid and can stably maintain the fixed orientation without causing changes in the orientation due to external fields or external forces, usually at temperatures ranging from 0 to 50°C, or under more severe conditions ranging from -30 to 70°C. In the present invention, as described below, it is preferable to fix the orientation state of the cholesteric liquid crystal phase by a curing reaction that proceeds by ultraviolet irradiation. In a layer in which a cholesteric liquid crystal phase is fixed, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained in the layer; ultimately, the composition in the layer does not need to exhibit liquid crystallinity.

[0163] The method of curing treatment is not particularly limited, and examples thereof include photocuring treatment and heat curing treatment. Among these, photoirradiation treatment is preferred, and ultraviolet irradiation treatment is more preferred. As mentioned above, the liquid crystal compound is preferably a liquid crystal compound having a polymerizable group. When the liquid crystal compound has a polymerizable group, the curing treatment is preferably a polymerization reaction by light irradiation (particularly ultraviolet irradiation), and more preferably a radical polymerization reaction by light irradiation (particularly ultraviolet irradiation). For ultraviolet irradiation, a light source such as an ultraviolet lamp is used. The amount of ultraviolet irradiation energy is not particularly limited, but is generally 100 to 800 mJ / cm. ２ The time for irradiating with ultraviolet light is not particularly limited, but may be determined appropriately from the viewpoints of both sufficient strength of the resulting layer and productivity.

[0164] (Aspect of Using Second Liquid Crystal Composition Containing Chiral Dopant Y) Hereinafter, a method for producing a cholesteric liquid crystal layer using a second liquid crystal composition containing chiral dopant Y (hereinafter also referred to as "Step 2Y") will be described.

[0165] Production method 2Y includes at least the following steps 2Y-1 and 2Y-2: step 2Y-1: forming a second composition layer on the liquid crystal layer using a second liquid crystal composition containing chiral dopant Y and a liquid crystal compound, the second composition layer satisfying the following condition 1 or 2: step 2Y-2: performing a cooling treatment or a heating treatment on the second composition layer to cholesterically align the liquid crystal compound in the second composition layer, thereby forming a cholesteric liquid crystal layer: condition 1: at least a portion of the liquid crystal compound in the second composition layer is tilted relative to the surface of the second composition layer; and condition 2: the liquid crystal compound is oriented such that the tilt angle of the liquid crystal compound in the second composition layer changes continuously along the thickness direction. When the liquid crystal compound has a polymerizable group, step 2Y preferably includes performing a curing treatment on the second composition layer, as described below.

[0166] The materials used in each step and the procedures for each step will be described in detail below.

[0167] <<Step 2Y-1>> Step 2Y-1 is a step of forming a second composition layer on a liquid crystal layer using a second liquid crystal composition (hereinafter also referred to as "composition Y") containing a chiral dopant Y and a liquid crystal compound, the second composition layer satisfying the above-mentioned condition 1 or the above-mentioned condition 2. Step 2Y-1 is similar to the above-mentioned Step 2X-1 in all steps except that composition Y is used instead of composition X, and therefore a description thereof will be omitted.

[0168] Composition Y Composition Y contains a liquid crystal compound and a chiral agent Y whose helical twisting power changes with temperature. Each component will be described below. As described above, the absolute value of the weighted average helical twisting power of the chiral agent in the second composition layer is determined by the temperature T １１ In the case of 0.0 to 1.9 μm, for example, the second composition layer is easily formed. －１ and 0.0 to 1.5 μm －１ is preferable, and 0.0 to 0.5 μm －１ is more preferably 0 μm －１ Therefore, it is particularly preferable that the chiral agent Y is １１If the composition Y has a helical twisting power exceeding the predetermined range at the temperature T １１ In step 2Y-1, it is preferable that the helical twisting power of the chiral agent Y is offset to approximately zero (i.e., the weighted average helical twisting power of the chiral agent in the composition layer is set to the above-mentioned predetermined range). It is also preferable that the chiral agent YA does not change its helical twisting power with temperature change. Furthermore, when the second liquid crystal composition contains multiple types of chiral agents Y as the chiral agent, and when the temperature T １１ When the weighted average helical twisting power of the multiple chiral agents Y is outside the above-mentioned range, the term "another chiral agent YA that induces a helical twist in the opposite direction to that of the chiral agent Y" refers to a chiral agent that induces a helical twist in the opposite direction to the weighted average helical twisting power of the multiple chiral agents Y. １１ When the compound has no helical twisting power but has the property of increasing the helical twisting power with temperature change, it is not necessary to use the chiral agent YA in combination.

[0169] The following describes various materials contained in composition Y. Note that, among the materials contained in composition Y, components other than the chiral agent are the same as the materials contained in composition X, and therefore description thereof will be omitted.

[0170] Chiral Agent Y, the Helical Twisting Power of which Changes upon Cooling or Heating: The chiral agent Y is a compound that induces helical twist in a liquid crystal compound, and is not particularly limited as long as it is a chiral agent whose helical twisting power increases upon cooling or heating. Here, "cooling or heating" refers to the cooling or heating treatment carried out in step 2Y-1. The upper limit of the cooling or heating temperature is usually about ±150°C (in other words, a chiral agent whose helical twisting power increases upon cooling or heating within ±150°C is preferred). Among these, a chiral agent whose helical twisting power increases upon cooling is preferred.

[0171] The chiral agent Y may be liquid crystalline or non-liquid crystalline. The chiral agent can be selected from various known chiral agents (for example, "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). The chiral agent Y generally contains an asymmetric carbon atom. However, an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom can also be used as the chiral agent Y. Examples of the axially asymmetric compound or the planar asymmetric compound include binaphthyl, helicene, paracyclophane, and derivatives thereof. The chiral agent Y may have a polymerizable group. Among these, the chiral agent Y is preferably an optically active isosorbide-based compound, an optically active isomannide-based compound, or an optically active binaphthol-based compound, in view of the large difference in helical twisting power after temperature change, and more preferably an optically active binaphthol-based compound.

[0172] The total content of the chiral agent in composition Y (total content of all chiral agents in composition Y) is preferably 2.0% by mass or more, more preferably 3.0% by mass or more, relative to the total mass of the liquid crystal compound. Furthermore, the upper limit of the total content of the chiral agent in composition X is preferably 15.0% by mass or less, more preferably 12.0% by mass or less, relative to the total mass of the liquid crystal compound, in terms of suppressing haze in the cholesteric liquid crystal layer. It should be noted that a smaller amount of the chiral agent Y is preferred because it tends not to affect the liquid crystallinity. Therefore, the chiral agent Y is preferably a compound with a strong twisting force so that even a small amount can achieve a twisted orientation with the desired helical pitch.

[0173] Chiral Agent YA The chiral agent YA is a compound that induces helical twist in the liquid crystal compound, and preferably has a helical twist power (HTP) that does not change with temperature change. The chiral agent YA may be liquid crystalline or non-liquid crystalline. The chiral agent XA generally contains an asymmetric carbon atom. However, an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom can also be used as the chiral agent YA. The chiral agent YA may have a polymerizable group. A known chiral agent can be used as the chiral agent YA. The liquid crystal composition contains one chiral agent Y alone, and the chiral agent Y is oriented at the temperature T １１ Within a predetermined range (for example, 0.0 to 1.9 μm －１ ), the chiral agent YA is preferably a chiral agent that induces a helix in the opposite direction to that of the chiral agent Y. That is, for example, when the helix induced by the chiral agent Y is right-handed, the helix induced by the chiral agent YA is left-handed. Also, when the liquid crystal composition contains multiple types of chiral agents Y as chiral agents, and the temperature T １１ In the above, when the weighted average helical twisting power of the plurality of chiral agents Y exceeds the above-mentioned predetermined range, the chiral agent YA is preferably a chiral agent that induces a helical twist in the opposite direction to the weighted average helical twisting power.

[0174] <<Step 2Y-2>> Step 2Y-2 is a step in which the second composition layer obtained in Step 2Y-1 is subjected to a cooling treatment or a heating treatment to change the helical twisting power of the chiral dopant Y and to cholesterically align the liquid crystal compound in the composition layer to form a cholesteric liquid crystal layer. In this step, it is particularly preferable to cool the composition layer.

[0175] When cooling the composition layer, it is preferable to cool the composition layer so that the temperature of the composition layer decreases by 30°C or more, since this provides better reflection anisotropy of the cholesteric liquid crystal layer. In particular, it is preferable to cool the composition layer so that the temperature decreases by 40°C or more, and it is more preferable to cool the composition layer so that the temperature decreases by 50°C or more, since this provides better effects. The upper limit of the temperature decrease in the cooling treatment is not particularly limited, but is typically about 150°C. In other words, the cooling treatment is intended to cool the composition layer to T-30°C or less, where T°C is the temperature of the composition layer that satisfies condition 1 or condition 2 obtained in step 1 before cooling. The cooling method is not particularly limited, and examples include a method in which the liquid crystal layer having the composition layer disposed thereon is allowed to stand in an atmosphere at a predetermined temperature.

[0176] Although there is no limitation on the cooling rate in the cooling treatment, it is preferable to set the cooling rate to a certain level in order to improve the reflection anisotropy of the cholesteric liquid crystal layer. Specifically, the maximum cooling rate in the cooling treatment is preferably 1°C or more per second, more preferably 2°C or more per second, and even more preferably 3°C or more per second. The upper limit of the cooling rate is not particularly limited, but is often 10°C or less per second.

[0177] In the method for producing a cholesteric liquid crystal layer of the present invention, if the composition layer is exposed to wind, unevenness in the surface condition of the formed cholesteric liquid crystal layer may occur. In consideration of this point, in the method for producing a cholesteric liquid crystal layer of the present invention, it is preferable that the wind speed in the environment to which the composition layer is exposed is low throughout all steps of step 2Y. Specifically, in the method for producing a cholesteric liquid crystal layer of the present invention, it is preferable that the wind speed in the environment to which the composition layer is exposed is 1 m / s or less throughout all steps of step 2Y.

[0178] When the composition layer is heated, the upper limit of the temperature increase range during the heat treatment is not particularly limited, but is usually about 150°C.

[0179] <<Curing Treatment>> When the liquid crystal compound has a polymerizable group, it is preferable to perform a curing treatment on the second composition layer. The procedure for performing the curing treatment on the second composition layer is the same as the method described in Production Method 2X, and the preferred embodiments are also the same.

[0180] [Uses] The head-up display system of the present invention can be used in a variety of applications, including, for example, an in-vehicle head-up display system.

[0181] The features of the present invention will be explained in more detail below with reference to examples. The materials, reagents, amounts and proportions of substances, and procedures shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the following examples.

[0182] [Various Components] <Chiral Agent> (Synthesis of Chiral Agent CD-1) Chiral agent CD-1 was synthesized according to the following synthesis procedure. Note that the chiral agent CD-1 has a left-handed helical direction and its helical twisting power does not change with temperature changes or light irradiation.

[0183]

[0184] (Synthesis of chiral agent CD-2) The following chiral agent CD-2 was synthesized and used according to JP-A No. 2002-338575. The chiral agent CD-2 has a right-handed helical direction and its helical twisting power changes upon irradiation with light.

[0185]

[0186] (Synthesis of chiral agent CD-2A) The following chiral agent CD-2A was synthesized and used according to JP-A No. 2002-338575. The chiral agent CD-2A has a right-handed helical direction and its helical twisting power changes upon irradiation with light.

[0187]

[0188] <Liquid Crystal Compound> As the discotic liquid crystal compound, the following discotic liquid crystal compound D-1 described in JP-A-2007-131765 was used.

[0189]

[0190] Liquid crystal compound LC-1

[0191]

[0192] <Surfactant> (Surfactant S-1) Surfactant S-1 is the following compound described in Japanese Patent No. 5774518.

[0193]

[0194] [Example 1] <Preparation of Reflective Member> (Saponification of Cellulose Acylate Film) A 40 μm cellulose acylate film obtained by the same preparation method as in Example 20 of WO 2014 / 112575 was passed through a dielectric heating roll at a temperature of 60° C. to raise the film surface temperature to 40° C., and then an alkaline solution having the composition shown below was applied to one side of the film using a bar coater in an amount of 14 mL / m. ２ The coating was then allowed to stand for 10 seconds under a steam-type far-infrared heater (manufactured by Noritake Co., Ltd.) heated to 110°C. Next, pure water was applied at a rate of 3 mL / m using the same bar coater. ２ The film was then washed with water using a fountain coater and then dried with an air knife three times, and then allowed to stay in a drying zone at 70°C for 5 seconds to prepare a saponified cellulose acylate film 1. The in-plane retardation of the cellulose acylate film 1 at a wavelength of 550 nm was measured with an AxoScan and found to be 1 nm.

[0195] Composition of alkaline solution: Potassium hydroxide 4.7 parts by mass; Water 15.7 parts by mass; Isopropanol 64.8 parts by mass; Surfactant (C １６ H ３３ O (CH ２ CH ２ O) １０H) 1.0 part by mass Propylene glycol 14.9 parts by mass

[0196] (Alignment Film) On the saponified surface of the obtained saponified cellulose acylate film 1 (transparent support), a coating solution 1 for forming an alignment film having the composition shown below was applied at a rate of 24 mL / m using a wire bar coater. ２ The film was coated, dried with hot air at 100°C for 120 seconds, and then subjected to rubbing treatment (rayon cloth, pressure: 0.1 kgf (0.98 N), rotation speed: 1000 rpm, conveying speed: 10 m / min, number of strokes: 1 round trip) to form cellulose acylate film 1 with an alignment film.

[0197] ------------------------------------------------------------------ Coating liquid 1 for forming alignment film -------------------------------------------------- Modified polyvinyl alcohol shown below: 28 parts by mass Citrate ester (AS3, manufactured by Sankyo Chemical Co., Ltd.) 1.2 parts by mass Photoinitiator (Irgacure 2959, manufactured by BASF) 0.84 parts by mass Glutaraldehyde 2.8 parts by mass Water 699 parts by mass Methanol 226 parts by mass ------------------------------------------------------------------

[0198] Modified Polyvinyl Alcohol

[0199]

[0200] (Each Cholesteric Liquid Crystal Layer) First, the following liquid crystal layer 1 forming coating solution was applied to the rubbed surface of the alignment layer 1 of the alignment layer-attached cellulose acylate film 1 using a #3 wire bar, and then aged at 120° C. for 1 minute. Then, the coating solution was aged at 500 mJ / cm 2 at 30° C. under a nitrogen atmosphere. ２ The coating film was cured by irradiating it with ultraviolet light at an irradiation dose of 1000 to obtain a liquid crystal layer 1.

[0201] ------------------------------------------------------------------ Coating liquid for forming liquid crystal layer 1 ------------------------------------------------------------------ Discotic liquid crystal compound D-1 described above: 100 parts by mass Initiator Irg-907 (manufactured by BASF): 3.0 parts by mass Solvent (methyl ethyl ketone / cyclohexanone = 90 / 10 (mass ratio)) Amount to make the solute concentration 30% by mass ------------------------------------------------------------------

[0202] - Preparation of cholesteric liquid crystal layer R1 - After applying the following coating solution for forming liquid crystal layer R1 onto liquid crystal layer 1 using a #10 wire bar, the composition layer was aged for 1 minute at 90°C. Subsequently, the composition layer after aging was irradiated with light of 365 nm wavelength at 2 mW / cm from a light source (2UV Transilluminator, manufactured by UVP Corporation) at 30°C. ２ Subsequently, the film was irradiated with ultraviolet light at an irradiation intensity of 500 mJ / cm for 60 seconds at 30°C under a nitrogen atmosphere. ２ The liquid crystal compound was polymerized by irradiating it with ultraviolet light at an exposure dose of 1000 .mu.m to obtain a cholesteric liquid crystal layer R1 in which the cholesteric alignment state was fixed. The thickness of the obtained cholesteric liquid crystal layer R1 was 8.3 μm. The cholesteric liquid crystal layer R1 had a central wavelength of selective reflection in the red light wavelength range. As a result, a laminate R1 having, in this order, a cellulose acylate film 1, an alignment film, a liquid crystal layer 1, and a cholesteric liquid crystal layer R1 was obtained.

[0203] Coating liquid for forming liquid crystal layer R1 ---------------------------------------------------------------- Liquid crystal compound LC-1 100 parts by mass Surfactant S-1 0.1 parts by mass Chiral agent CD-1 5.5 parts by mass Chiral agent CD-2 5.5 parts by mass Initiator Irg-907 (manufactured by BASF) 2.0 parts by mass Solvent (methyl ethyl ketone / cyclohexanone=90 / 10 (mass ratio)) amount to give a solute concentration of 50% by mass

[0204] - Preparation of cholesteric liquid crystal layer G1 - After applying the following coating solution for forming liquid crystal layer G1 onto liquid crystal layer 1 using a #9 wire bar, the composition layer was aged for 1 minute at 90°C. Subsequently, the composition layer after aging was irradiated with light of 365 nm wavelength at 2 mW / cm from a light source (2UV transilluminator, manufactured by UVP Corporation) at 30°C. ２ Subsequently, the film was irradiated with ultraviolet light at an irradiation intensity of 500 mJ / cm for 60 seconds at 30°C under a nitrogen atmosphere. ２ The liquid crystal compound was polymerized by irradiating it with ultraviolet light at an exposure dose of 1000 .mu.m to obtain a cholesteric liquid crystal layer G1 in which the cholesteric alignment state was fixed. The thickness of the obtained cholesteric liquid crystal layer G1 was 6.9 μm. The cholesteric liquid crystal layer G1 had a central wavelength of selective reflection in the green light wavelength range. As a result, a laminate G1 having, in this order, a cellulose acylate film 1, an alignment film, a liquid crystal layer 1, and a cholesteric liquid crystal layer G1 was obtained.

[0205] Coating liquid for forming liquid crystal layer G1 ---------------------------------------------------------------- Liquid crystal compound LC-1 100 parts by mass Surfactant S-1 0.1 parts by mass Chiral agent CD-1 7.7 parts by mass Chiral agent CD-2 7.7 parts by mass Initiator Irg-907 (manufactured by BASF) 2.0 parts by mass Solvent (methyl ethyl ketone / cyclohexanone=90 / 10 (mass ratio)) amount to give a solute concentration of 50% by mass

[0206] - Preparation of cholesteric liquid crystal layer B1 - After applying the following coating solution for forming liquid crystal layer B1 onto liquid crystal layer 1 using a #8 wire bar, the composition layer was aged for 1 minute at 90°C. Subsequently, the composition layer after aging was irradiated with light of 365 nm wavelength at 2 mW / cm from a light source (2UV transilluminator, manufactured by UVP Corporation) at 30°C. ２ Subsequently, the film was irradiated with ultraviolet light at an irradiation intensity of 500 mJ / cm for 60 seconds at 30°C under a nitrogen atmosphere. ２ The liquid crystal compound was polymerized by irradiating it with ultraviolet light at an exposure dose of 1000 .mu.m to obtain a cholesteric liquid crystal layer B1 in which the cholesteric alignment state was fixed. The thickness of the obtained cholesteric liquid crystal layer B1 was 5.5 μm. The cholesteric liquid crystal layer B1 had a central wavelength of selective reflection in the blue light wavelength range. As a result, a laminate B1 having, in this order, a cellulose acylate film 1, an alignment film, a liquid crystal layer 1, and a cholesteric liquid crystal layer B1 was obtained.

[0207] Coating liquid for forming liquid crystal layer G1 ---------------------------------------------------------------- Liquid crystal compound LC-1 100 parts by mass Surfactant S-1 0.1 parts by mass Chiral agent CD-1 8.8 parts by mass Chiral agent CD-2 8.8 parts by mass Initiator Irg-907 (manufactured by BASF) 2.0 parts by mass Solvent (methyl ethyl ketone / cyclohexanone=90 / 10 (mass ratio)) amount to give a solute concentration of 50% by mass

[0208] (Retardation layer) The following retardation layer-forming coating solution was applied to the rubbed surface of the orientation film of the above-mentioned cellulose acylate film 1 with an orientation film using a #3 wire bar, and then dried and heated at 55°C for 1 minute.The film was then placed on a hot plate at 50°C and irradiated with ultraviolet light for 6 seconds using an electrodeless lamp "D bulb" (60 mW / cm) manufactured by Fusion UV Systems, Inc., to fix the liquid crystal phase, thereby obtaining a retardation layer with a thickness of 0.8 μm.

[0209] ------------------------------------------------------------------ Coating liquid for forming retardation layer ------------------------------------------------------------------ Liquid crystal compound LC-1 100 parts by mass ------------------------------------------------------------------ Surfactant S-1 0.1 part by mass -- Initiator IRGACURE OXE01 (manufactured by BASF) 0.75 parts by mass -- Solvent (methyl ethyl ketone) amount to give a solute concentration of 25% by mass ------------------------------------------------------------------

[0210] (Reflective Member) The cellulose acylate film 1 and the alignment film were peeled off from each of the laminates R1, G1, and B1 to obtain a cholesteric layer. Each cholesteric layer was laminated with the retardation layer obtained above via an adhesive, to obtain a reflective member 1 having the retardation layer, cholesteric liquid crystal layer R1, cholesteric liquid crystal layer G1, and cholesteric liquid crystal layer B1 in this order, with an adhesive layer between each of the layers.

[0211] <Preparation of Windshield Glass> As the first and second glass plates, curved glass plates (visible light transmittance 90%) measuring 1000 mm in length, 1500 mm in width, and 2 mm in thickness were prepared. A black ceramic (black ceramic) was printed on the inner periphery of the second glass plate (vehicle interior side) using the screen printing method described in JP 2004-058310 A. A 0.76 mm thick PVB film manufactured by Sekisui Chemical Co., Ltd. was prepared as an interlayer film, and a laminate X was prepared by the following method. Using the above laminate X, a laminate was prepared in the following order: protect film 1 / HC layer / resin substrate / retardation layer / reflective layer / polarization conversion layer / heat seal layer / second glass plate / interlayer film / first glass plate. This was placed in a rubber bag and the pressure was reduced to 10 kPa (0.1 atmospheres) using a vacuum pump. The temperature was then increased to 115°C under reduced pressure, maintained for 60 minutes, and then temporarily returned to room temperature and pressure. The laminate was then placed in an autoclave (manufactured by Kurihara Manufacturing Co., Ltd.) at 140°C and 1.3 MPa (13 atmospheres) for 60 minutes to remove air bubbles, and a glass sample was prepared in which the laminate and the glass substrate were bonded together by the heat seal layer. The protective film 1 was then peeled off to obtain a windshield glass 1.

[0212] (Preparation of Laminate X) - Preparation of Curable Composition for Forming Hard Coat Layer (HC Layer) - The components shown in the table below were mixed and filtered through a polypropylene filter having a pore size of 10 μm to prepare a curable composition for forming an HC layer, HC-1. The blending amount of each component shown in the table is expressed in parts by mass.

[0213]

[0214] PAG-1 is the following compound:

[0215]

[0216] - Preparation of composition for forming heat-seal layer - The components shown in the table below were mixed and filtered through a polypropylene filter with a pore size of 10 μm to prepare composition for forming heat-seal layer HS-1. The blending amount of each component shown in Table 2 is expressed in parts by mass.

[0217]

[0218] - Preparation of reflective layer-forming composition, retardation layer-forming composition, and polarization conversion layer- The components were mixed according to the formulations shown in Table 3 below and filtered through a polypropylene filter with a pore size of 10 μm to prepare reflective layer-forming compositions BG1, R1, and IR1, retardation layer-forming composition A1, and polarization conversion layer-forming composition TW-1. The blending amount of each component shown below is expressed in parts by mass. Note that mixture 1, alignment control agent 1, and alignment control agent 2 are the following compounds.

[0219]

[0220]

[0221]

[0222]

[0223] - Saponification of Cellulose Acylate Film - A 100 μm thick cellulose acylate film was prepared by the same preparation method as in Example 20 of WO 2014 / 112575. UV-531 manufactured by Teisei Kako Co., Ltd. was added to this cellulose acylate film as an ultraviolet absorber. The amount added was 3 phr (per hundred resin). The prepared cellulose acylate film was passed through a dielectric heating roll at a temperature of 60° C. to raise the surface temperature of the film to 40° C., and then an alkaline solution having the composition shown below was applied to one side of the film using a bar coater in an amount of 14 mL / m 2 The coating was then allowed to stand for 10 seconds under a steam-type far-infrared heater (manufactured by Noritake Co., Ltd.) heated to 110°C. Next, pure water was applied at a rate of 3 mL / m using the same bar coater. 2The film was then washed with water using a fountain coater and then dried with an air knife three times, and then allowed to stay in a drying zone at 70° C. for 5 seconds to dry, thereby preparing a saponified cellulose acylate film X.

[0224] --------------------------------------------------- Composition of alkaline solution --------------------------------------------------- Potassium hydroxide 4.7 parts by mass Water 15.7 parts by mass Isopropanol 64.8 parts by mass Surfactant (C １６ H ３３ O (CH ２ CH ２ O) １０ H) 1.0 part by mass Propylene glycol 14.9 parts by mass

[0225] - Formation of Hard Coat Layer - An HC layer-forming curable composition HC-1 was applied to the surface of the cellulose acylate film 1X prepared above opposite to the saponification treatment surface, and cured to form an HC1 layer with a thickness of 6 μm. Specifically, the application and curing methods were as follows. The HC layer-forming curable composition HC-1 was applied at a conveying speed of 30 m / min by the die coating method using a slot die described in Example 1 of JP-A No. 2006-122889, and dried at an atmospheric temperature of 60°C for 60 seconds to obtain a coating film. Thereafter, under a nitrogen purge, an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) with an oxygen concentration of about 0.1% by volume and an illuminance of 150 mW / cm was applied to the coating film. ２ , irradiation amount 600mJ / cm ２ The coating film was cured by irradiating it with ultraviolet light of 1000 kJ / cm 2 to form an HC layer, thereby obtaining a film HC1 having a resin substrate and an HC layer.

[0226] - Formation of Heat Seal Layer - The heat seal layer-forming composition HS-1 was applied to the surface of the film HC1 opposite the hard coat layer using a wire bar so that the film would have a dry thickness of 0.8 μm, and then dried at 120° C. for 1 minute to form a coating film. Thereafter, under a nitrogen purge, an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) with an oxygen concentration of about 0.1% by volume and an illuminance of 150 mW / cm was used to illuminate the coating film. ２ , irradiation amount 300mJ / cm ２ The coating was cured by irradiating it with ultraviolet light of 1000 kJ / cm 2 , thereby preparing a laminate X having a structure of HC layer / resin substrate / heat seal layer.

[0227] Example 2 A coating liquid for forming a liquid crystal layer R2 was prepared using the same procedure as for the coating liquid for forming a liquid crystal layer R1, except that the solute concentration of the coating liquid for forming a liquid crystal layer R1 was changed to 20% by mass. A coating liquid for forming a liquid crystal layer G2 was prepared using the same procedure as for the coating liquid for forming a liquid crystal layer G1, except that the solute concentration of the coating liquid for forming a liquid crystal layer B1 was changed to 20% by mass. A coating liquid for forming a liquid crystal layer B2 was prepared using the same procedure as for the coating liquid for forming a liquid crystal layer B1, except that the coating liquid for forming a liquid crystal layer R2 was formed using a #4 wire bar, the coating liquid for forming a liquid crystal layer G2 was formed using a #3.5 wire bar, and the coating liquid for forming a liquid crystal layer B2 was formed using a #3 wire bar. Each cholesteric layer was prepared using the same procedure as for each cholesteric layer in Example 1, and each laminate was obtained. Next, a reflective member 2 was obtained using the same procedure as in Example 1. The cholesteric liquid crystal layer R2 was 1.2 μm, the cholesteric liquid crystal layer G2 was 1.0 μm, and the cholesteric liquid crystal layer B2 was 0.8 μm.

[0228] Example 3 A reflecting member 3 and a windshield glass 2 were obtained in the same manner as in Example 1, except that the windshield glass 2 was produced without using the laminate X in the windshield glass 1 .

[0229] Comparative Example 1 Instead of the reflecting member and the projector described below, a monitor (iPad (fourth generation) manufactured by Apple Inc.) was used.

[0230] Comparative Example 2: A coating solution for forming a liquid crystal layer R3 was applied to the rubbed surface of the alignment film of the alignment film-attached cellulose acylate film 1 prepared in Example 1 using a #10 wire bar, dried, and then heated at 55°C for 1 minute. The film was then placed on a hot plate at 50°C and irradiated with ultraviolet light for 6 seconds using an electrodeless lamp "D bulb" (60 mW / cm) manufactured by Fusion UV Systems, Inc., to fix the liquid crystal phase, thereby obtaining a cholesteric liquid crystal layer R3 having a thickness of 8.3 μm. Next, a coating solution for forming a liquid crystal layer G3 was applied to the cholesteric liquid crystal layer R3 using a #9 wire bar, dried, and then heated at 55°C for 1 minute. The film was then placed on a hot plate at 50°C and irradiated with ultraviolet light for 6 seconds using an electrodeless lamp "D bulb" (60 mW / cm) manufactured by Fusion UV Systems, Inc., to fix the liquid crystal phase, thereby obtaining a cholesteric liquid crystal layer G3 having a thickness of 6.9 μm. Furthermore, a coating solution for forming a liquid crystal layer B3 was applied to the obtained cholesteric liquid crystal layer G3 using a #8 wire bar, and then dried and heated at 55 ° C for 1 minute. The layer was then placed on a hot plate at 50 ° C and irradiated with ultraviolet light for 6 seconds using an electrodeless lamp "D bulb" (60 mW / cm) manufactured by Fusion UV Systems, Inc., to fix the liquid crystal phase, thereby obtaining a cholesteric liquid crystal layer B3 with a thickness of 5.5 μm, and a reflective member 4 was produced. The reflective member 4 has, in this order, a cellulose acylate film, an alignment film, a retardation layer, a cholesteric layer R3, a cholesteric layer G3, and a cholesteric layer B3. The cross-sectional SEM observation described below revealed that the alignment directions of the light and dark portions of each cholesteric layer derived from the cholesteric liquid crystal phase of the reflective member 4 were 90° (the alignment direction was not inclined relative to one of the main surfaces of the cholesteric liquid crystal layer), and the light and dark portions had a linear structure rather than a wavy structure.

[0231] ------------------------------------------------ Coating liquid for forming liquid crystal layers R3, G3, B3 ------------------------------------------------ - 100 parts by mass of the above liquid crystal compound LC-1 - 0.1 parts by mass of the above surfactant S-1 - Right-handed chiral agent LC756 (manufactured by BASF) The contents were adjusted to match the desired dominant reflection wavelength of each liquid crystal layer as follows: Liquid crystal layer R3: 445 nm Liquid crystal layer G3: 520 nm Liquid crystal layer B3: 635 nm - Initiator IRGACURE OXE01 (manufactured by BASF) 0.75 parts by mass - Solvent (methyl ethyl ketone) Amount to give a solute concentration of 50% by mass ------------------------------------------------

[0232] Comparative Example 3 Preparation of Reflective Member (Alignment Film) The alignment film-forming coating solution 2 was applied onto a cellulose acylate film 1 using a #3.6 wire bar coater. The film was then dried at 45°C for 60 seconds, and irradiated with 500 mJ / cm 2 UV light at 25°C using an ultraviolet ray irradiation device. ２ The film was irradiated with ultraviolet light of 1000 kJ / cm to prepare a cellulose acylate film 2 having an alignment layer.

[0233] ------------------------------------------------------------------ Coating liquid 2 for forming alignment film ------------------------------------------------------------------ KAYARAD PET30 (manufactured by Nippon Kayaku Co., Ltd.) 100 parts by mass IRGACURE 907 (manufactured by BASF) 3.0 parts by mass Kayacure DETX (manufactured by Nippon Kayaku Co., Ltd.) 1.0 part by mass Methyl isobutyl ketone 243 parts by mass ------------------------------------------------------------------

[0234] (Each Cholesteric Liquid Crystal Layer) A coating liquid for forming a liquid crystal layer R4, a coating liquid for forming a liquid crystal layer G4, and a coating liquid for forming a liquid crystal layer B4 were prepared in the same manner as in the coating liquid for forming a liquid crystal layer R1, a coating liquid for forming a liquid crystal layer G1, and a coating liquid for forming a liquid crystal layer B1, except that the following compound S-3 was used instead of surfactant S-1. Next, the coating liquid for forming a liquid crystal layer R4 was applied to the rubbed surface of the alignment film of the alignment film-attached cellulose acylate film 2 using a #10 wire bar, dried, and then heat-treated at 55°C for 1 minute. The film was then placed on a hot plate at 50°C and irradiated with ultraviolet light for 6 seconds using an electrodeless lamp "D bulb" (60 mW / cm) manufactured by Fusion UV Systems, Inc. to fix the liquid crystal phase, thereby obtaining a cholesteric liquid crystal layer R4 having a thickness of 8.3 μm. Next, a coating solution for forming a liquid crystal layer G4 was applied onto the cholesteric liquid crystal layer R4 using a #9 wire bar, dried, and heated at 55 ° C. for 1 minute, then placed on a hot plate at 50 ° C. and irradiated with ultraviolet light for 6 seconds using an electrodeless lamp "D bulb" (60 mW / cm) manufactured by Fusion UV Systems, Inc. to fix the liquid crystal phase, thereby obtaining a cholesteric liquid crystal layer G3 having a thickness of 6.9 μm. Furthermore, a coating solution for forming a liquid crystal layer B4 was applied onto the obtained cholesteric liquid crystal layer G3 using a #8 wire bar, dried, and heated at 55 ° C. for 1 minute, then placed on a hot plate at 50 ° C. and irradiated with ultraviolet light for 6 seconds using an electrodeless lamp "D bulb" (60 mW / cm) manufactured by Fusion UV Systems, Inc. to fix the liquid crystal phase, thereby obtaining a cholesteric liquid crystal layer B4 having a thickness of 5.5 μm, and a reflective member 5 was produced. The reflective member 5 includes, in this order, a cellulose acylate film, an alignment film, a retardation layer, a cholesteric layer R4, a cholesteric layer G4, and a cholesteric layer B4. As a result of cross-sectional SEM observation described below, it was found that in each cholesteric layer of the reflective member 5, the alignment direction of the light and dark portions derived from the cholesteric liquid crystal phase of the reflective member 5 was 90° (the alignment direction was not inclined with respect to one of the main surfaces of the cholesteric liquid crystal layer), and the light and dark portions had a wavy structure.

[0235] Compound S-3

[0236]

[0237] Comparative Example 4 Preparation of Reflective Member (Alignment Film) Using a spin coater, the alignment film-forming coating solution 3 was applied to the cellulose acylate film 1 at 2500 rpm for 30 seconds, followed by drying on a hot plate at 60° C. for 60 seconds to prepare the cellulose acylate film 3 with an alignment film.

[0238] ------------------------------------------------------------------ Coating liquid 3 for forming alignment film -------------------------------------------------- 1.00 parts by mass of the following photoalignment material - Water 16.00 parts by mass - Butoxyethanol 42.00 parts by mass - Propylene glycol monomethyl ether 42.00 parts by mass ------------------------------------------------------------------

[0239] Material for photo alignment

[0240]

[0241] The alignment film was exposed using the exposure device shown in FIG. 7 of WO 2023 / 122127 to form alignment films P-1, P-2, and P-3 having alignment patterns. The exposure device used was one that emitted laser light with a wavelength of 325 nm. The exposure dose by the interference light was 300 mJ / cm. ２The intersecting angle (crossing angle α) of the two beams was adjusted so that one period Λ (the length of 180° rotation of the optical axis) of the alignment pattern formed by the interference of the two laser beams was 0.033 μm for P-1, 0.028 μm for P-2, and 0.025 μm for P-3. Cholesteric liquid crystal solution R3 was applied to the alignment film P-1 using a #10 wire bar, then dried and heated at 55 ° C for 1 minute, placed on a 50 ° C hot plate, and irradiated with ultraviolet light for 6 seconds using an electrodeless lamp "D bulb" (60 mW / cm) manufactured by Fusion UV Systems, Inc., to fix the liquid crystal phase, and a laminate R5 having a cholesteric liquid crystal R5 layer with a thickness of 8.3 μm was obtained. Cholesteric liquid crystal solution G3 was applied to alignment film P-2 using a #9 wire bar, then dried and heated at 55 ° C. for 1 minute, placed on a 50 ° C. hot plate, and irradiated with ultraviolet light for 6 seconds using an electrodeless lamp "D bulb" (60 mW / cm) manufactured by Fusion UV Systems, Inc. to fix the liquid crystal phase, resulting in a laminate G5 having a 6.9 μm thick cholesteric liquid crystal G5 layer. Cholesteric liquid crystal solution B3 was applied to alignment film P-3 using a #8 wire bar, then dried and heated at 55 ° C. for 1 minute, placed on a 50 ° C. hot plate, and irradiated with ultraviolet light for 6 seconds using an electrodeless lamp "D bulb" (60 mW / cm) manufactured by Fusion UV Systems, Inc. to fix the liquid crystal phase, resulting in a laminate B5 having a 5.5 μm thick cholesteric liquid crystal B5 layer. A reflective member 6 was produced in the same manner as in Example 1, except that the laminate R1, laminate G1, and laminate B1 in Example 1 were changed to laminate R5, laminate G5, and laminate B5, respectively. As a result of cross-sectional SEM observation described below, it was found that in each cholesteric layer of the reflective member 6, the alignment direction of the light and dark portions derived from the cholesteric liquid crystal phase of the reflective member 6 was 60° (the alignment direction was inclined with respect to one main surface of the cholesteric liquid crystal layer), and the light and dark portions had a linear structure rather than a wavy structure.

[0242] [Cross-Sectional SEM Observation] A cross section perpendicular to one main surface of each of the cholesteric liquid crystal layers in each of the laminates R, G, and B was cut using an ultramicrotome (Ultracut UCT manufactured by Leica), and cross-sectional images (no pretreatment, acceleration voltage: 2 kV, magnification: 15K times) were obtained using a high-resolution field emission scanning electron microscope (FE-SEM, S-4800 manufactured by Hitachi High-Technologies Corporation). Each state shown in the table below was observed from the obtained cross-sectional images.

[0243] [Reflectance] The integrated reflectance spectrum of each reflective member was measured using a spectrophotometer ("V-670" manufactured by JASCO Corporation) equipped with an integrating sphere so that light (unpolarized) was incident from the retardation layer of each reflective member, including specularly reflected light. For the obtained integrated spectrum, the reflectance at 10 nm intervals and the maximum reflectance in the wavelength range of 380 to 780 nm were measured.

[0244] [Optical Evaluation] A head-up display system was fabricated using the fabricated reflective member, windshield glass, and projector. Specifically, the windshield glass was tilted so that the second glass plate (inner glass) was facing downward. An image formed by the projector using the reflective member was projected from the second glass plate. The following optical evaluation was performed using the obtained head-up display system.

[0245] <Reflection of external light> External light, including sunlight, was incident on the upper part of the windshield glass toward the reflective member, and the observer's position was fixed. The reflection of external light was evaluated according to the following criteria: "A": There was little reflection of external light, and a virtual image was visible. "B": There was a lot of reflection of external light, and a virtual image was not visible.

[0246] <Eyebox Range> The eyebox range was evaluated by positioning the device so that external light, including sunlight, would not shine toward the reflective member, and by changing the observer's position. "A": The eyebox range was wider than that of Comparative Example 2. "B": The eyebox range was the same as or narrower than that of Comparative Example 2.

[0247] <Brightness> Light was projected from the glass surface on the retardation layer side so that p-polarized light was incident in a direction at 65° relative to the normal direction of the windshield glass. The reflectance spectrum of the incident p-polarized specularly reflected light was measured using a spectrophotometer (V-670, manufactured by JASCO Corporation). In this example, the specularly reflected light was light in the direction opposite to the incident direction relative to the normal direction within the incident plane, at 65° relative to the normal direction. At this time, the long side direction of the windshield glass and the transmission axis of the incident p-polarized light in the spectrophotometer were parallel. Therefore, the transmission axis of the retardation layer was at 45° relative to the p-polarized light. In accordance with JIS R3106, the reflectance was multiplied by a coefficient corresponding to luminosity and the emission spectrum of a typical liquid crystal display device at wavelengths of 380 to 780 nm in 10 nm increments to calculate the projected image reflectance, and the result was evaluated as brightness. Brightness was evaluated according to the following evaluation criteria. "A": Projected image reflectance is 35% or more. "B": Projected image reflectance is less than 35%.

[0248] <Double image> hcl = Black PET (absorbent material) was attached to the glass surface of the windshield glass on the polarization conversion layer side, and p-polarized light was incident on the windshield glass from a direction of 65°, as in the brightness evaluation, and the reflectance spectrum of the specularly reflected light was measured with a spectrophotometer (V-670, manufactured by JASCO Corporation). The double image was evaluated as the ratio of the reflection and brightness on the back side of the laminated glass, "[(brightness - brightness with black PET attached) / brightness] x 100". "A": Less than 4% "B": 4% or more

[0249] In the table, the "R," "G," and "B" columns of "Cholesteric Liquid Crystal Layer" indicate whether each cholesteric liquid crystal layer corresponds to a cholesteric liquid crystal layer R having a central wavelength of selective reflection in the red light wavelength range, a cholesteric liquid crystal layer G having a central wavelength of selective reflection in the green light wavelength range, or a cholesteric liquid crystal layer B having a central wavelength of selective reflection in the blue light wavelength range. In the column "The alignment direction of the light and dark portions is tilted with respect to one of the main surfaces," "A" indicates that the alignment direction of the light and dark portions is tilted with respect to one of the main surfaces, and "B" indicates that this is not the case. In the column "The tilt of the helical axis changes in the in-plane direction," "A" indicates that the tilt of the helical axis of the cholesteric liquid crystal phase changes in the in-plane direction, and "B" indicates that this is not the case. In the column "The light and dark portions extend from one main surface to the other main surface," "A" indicates that the light and dark portions extend from one main surface to the other main surface, and "B" indicates that this is not the case. The "Repeated Region" column indicates that "A" indicates that the cholesteric liquid crystal layer has a region where the inclination of the helical axis of the cholesteric liquid crystal phase with respect to the main surface of the cholesteric liquid crystal layer repeatedly increases and decreases along one direction within the plane of the cholesteric liquid crystal layer, while "B" indicates that this is not the case. The "Tilt Angle" column indicates the tilt angle of the wavy structure (the angle between the arrangement direction of the light and dark portions and the main surface).

[0250]

[0251] It was confirmed that the head-up display system of the present invention can achieve the desired effects. A comparison between Example 1 and Example 2 confirmed that brightness is superior when the maximum reflectance of the reflectance measured at 10 nm intervals in the wavelength range of 380 to 780 nm is 30% or higher (when the reflectance of the cholesteric liquid crystal layer at wavelengths of 445 nm, 520 nm, and 635 nm is all 30% or higher). A comparison between Example 1 and Example 3 confirmed that double images can be further reduced when the windshield glass has a reflective layer and a polarization conversion layer.

[0252] REFERENCE SIGNS LIST 10 Head-up display system 12 Projector 14 Windshield glass 16 Shielding layer 20 Light source 22 Reflective member 24 Cholesteric liquid crystal layer 24A, 24B Main surface 26 Support 27 Bright area 28 Dark area 30 Dashboard 32 Transmitting window 42 Liquid crystal compound 50 First glass plate 52 Interlayer 54 Reflective film 56 Heat seal layer 58 Second glass plate 60 Polarization conversion layer 62 Selective reflection layer 64 Retardation layer 66 Transparent substrate 68R, 68G, 68B Cholesteric liquid crystal layer L1 Molecular axis A, B Region R １ Thickness direction 100 Second composition layer 102 First liquid crystal layer 102a Inclined alignment surface

Claims

1. A reflective component for a head-up display system arranged between a light source and a windshield glass in a head-up display system, comprising a cholesteric liquid crystal layer, in a cross section perpendicular to one main surface of the cholesteric liquid crystal layer, the alignment direction of light and dark areas derived from the cholesteric liquid crystal phase observed with a scanning electron microscope is inclined with respect to the one main surface of the cholesteric liquid crystal layer, and in the cross section, the inclination of the helical axis of the cholesteric liquid crystal phase changes in the in-plane direction.

2. A reflective member for a head-up display system as described in claim 1, having, in the cross section, a region in which the inclination of the helical axis of the cholesteric liquid crystal phase with respect to the main surface of the cholesteric liquid crystal layer alternates between regions where the inclination increases and regions where the inclination decreases along one direction within the plane of the cholesteric liquid crystal layer.

3. The reflective member for a head-up display system according to claim 1 or 2, wherein the maximum reflectance among the reflectances measured at wavelength intervals of 10 nm in the wavelength range of 380 to 780 nm is 30% or more.

4. The reflective member for a head-up display system according to claim 1 or 2, further comprising a retardation layer.

5. A head-up display system comprising: a projector including a light source; a reflective member for a head-up display system as described in claim 1 or 2, onto which projection light emitted from the projector is irradiated; and a windshield glass onto which the light reflected by the reflective member is irradiated.

6. The head-up display system of claim 5, wherein the windshield glass has a P-polarized reflective film.

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