Vehicular mirror with image display function

Abstract

To provide a vehicular mirror with an image display function, that is capable of bright image display and that allows observation of a mirror reflected image without irregularities.SOLUTION: Provided is a vehicular mirror with an image display function, that includes a half-mirror and an image display device. The half-mirror includes a high-Re phase difference film and a reflective layer. In the mirror with the image display function, the high-Re phase difference film, the reflective layer, and the image display device are disposed in this order, the high-Re phase difference film has a front face phase difference of 5000 nm or more, and the reflective layer is a linearly polarizing reflective layer or a circularly polarizing reflective layer.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a vehicle mirror with an image display function. [Background technology]

[0002] A vehicle mirror with an image display function that can display images such as images captured by an on-board camera on a vehicle mirror is described, for example, in Patent Document 1. In the vehicle mirror with an image display function disclosed in Patent Document 1, a liquid crystal display device is provided inside the housing of the vehicle mirror, and images are displayed through a half mirror provided in front of the vehicle mirror, thereby realizing image display on the mirror. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-201146 A [Patent Document 2] JP 2011-45427 A Summary of the Invention [Problem to be solved by the invention]

[0004] A half mirror normally has a visible light transmittance of about 30% to 70%, and a configuration including a half mirror potentially has the problem that the image will be darker than one without a half mirror. On the other hand, Patent Document 2 discloses a mirror with an information display function that can be used for interior, cosmetic, crime prevention, and safety mirrors. It is described that it is possible to eliminate light loss by using a reflective polarizing plate as a half mirror. However, when the inventors of the present invention constructed a mirror with an image display function using a reflective polarizing plate and used it in a vehicle, uneven brightness and color (rainbow color, etc.) occurred in the reflected image of the mirror. An object of the present invention is to provide a vehicle mirror with an image display function that is capable of displaying a bright image and enabling a reflected image of the mirror to be observed without unevenness. [Means for solving the problem]

[0005] The inventors conducted intensive research to solve the above-mentioned problems and discovered that the above-mentioned unevenness in the mirror reflected image can be confirmed when observing the external scenery through the rear window of a vehicle. Based on this finding, they conducted further research and completed the present invention.

[0006] That is, the present invention provides the following [1] to

[11] . [1] A vehicle mirror with an image display function, A half mirror and an image display device are included. The half mirror includes a high Re retardation film and a reflective layer, In the mirror with an image display function, the high Re phase difference film, the reflective layer, and the image display device are arranged in this order, The high Re retardation film has a front retardation of 5000 nm or more, The mirror with an image display function, wherein the reflective layer is a linearly polarized light reflective layer or a circularly polarized light reflective layer. [2] The mirror with an image display function according to [1], wherein the front phase difference is 7000 nm or more. [3] The mirror with an image display function according to [1] or [2], wherein the reflective layer is a circularly polarized reflective layer. [4] The mirror with an image display function according to [3], wherein the circularly polarized light reflective layer includes a cholesteric liquid crystal layer. [5] The mirror with image display function according to [4], wherein the circularly polarized light reflective layer comprises three or more cholesteric liquid crystal layers.

[0007] [6] Including a quarter wave plate, The mirror with an image display function according to [4] or [5], wherein the half mirror comprises the high Re phase difference film, the circularly polarized light reflective layer, and the quarter wavelength plate, in this order. [7] The mirror with an image display function according to [6], wherein the circularly polarized light reflective layer and the quarter-wave plate are in direct contact with each other. [8] The mirror with an image display function according to [3], wherein the circularly polarized light reflective layer includes a quarter wave plate and a linearly polarized light reflective plate in this order from the high Re retardation film side. [9] The half mirror includes a front plate, The mirror with an image display function according to any one of [1] to [8], comprising the front plate, the high Re retardation film, and the reflective layer in this order.

[10] The half mirror includes a front plate, the front plate is a laminated glass including two glass plates and an intermediate layer between the two glass plates; The intermediate layer includes the high Re retardation film. The mirror with an image display function according to any one of [1] to [8].

[11] The half mirror is a laminated glass including two glass plates and an intermediate layer between the two glass plates, The intermediate layer includes the high Re retardation film and the reflective layer. The mirror with an image display function according to any one of [1] to [8]. Effect of the Invention

[0008] According to the present invention, a vehicle mirror with an image display function is provided that is capable of displaying a bright image and enabling observation of a mirror reflected image without unevenness. When the mirror with an image display function of the present invention is used as an inner mirror of a vehicle, the outside scenery through the rear window can be observed as a mirror reflected image without unevenness. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described in detail below. In this specification, the word "to" is used to mean that the numerical values ​​before and after it are included as the lower and upper limits. In this specification, for example, angles such as "45°", "parallel", "perpendicular" or "orthogonal" mean that the difference from the exact angle is within a range of less than 5 degrees unless otherwise specified. The difference from the exact angle is preferably less than 4 degrees, and more preferably less than 3 degrees. In this specification, "(meth)acrylate" is used to mean "either one or both of acrylate and methacrylate."

[0010] In this specification, the term "selective" in relation to circularly polarized light means that the amount of either the right-handed or left-handed circularly polarized component is greater than the other circularly polarized component. Specifically, when the term "selective" is used, the degree of circular polarization of light is preferably 0.3 or more, more preferably 0.6 or more, and even more preferably 0.8 or more. It is even more preferably substantially 1.0. Here, the degree of circular polarization is defined as the intensity of the right-handed circularly polarized component of light, expressed as I R , the intensity of the left circularly polarized component is I L Then, |I R -I L | / (I R +I L ) is the value expressed as

[0011] In this specification, the term "sense" for circularly polarized light means right-handed or left-handed circularly polarized light. The sense of circularly polarized light is defined as right-handed circularly polarized light when the tip of the electric field vector rotates clockwise as time increases when the light is viewed as traveling toward the user, and left-handed circularly polarized light when the tip rotates counterclockwise as time increases.

[0012] In this specification, the term "sense" may be 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, the cholesteric liquid crystal selectively reflects right-handed circularly polarized light and transmits left-handed circularly polarized light, and when the sense is left, the cholesteric liquid crystal reflects left-handed circularly polarized light and transmits right-handed circularly polarized light.

[0013] Visible light is electromagnetic radiation with wavelengths visible to the human eye, ranging from 380nm to 780nm. Infrared light (infrared light) is electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves. Among infrared rays, near-infrared light is electromagnetic radiation with wavelengths ranging from 780nm to 2500nm.

[0014] In this specification, the term "image" in relation to the mirror with image display function means an image that can be visually observed from the front side when an image is displayed on the image display unit of the image display device. Also, in this specification, the term "mirror reflected image" in relation to the mirror with image display function means an image that can be visually observed from the front side when no image is displayed on the image display unit of the image display device.

[0015] In this specification, the front retardation is a value measured using AxoScan manufactured by Axometrix, or a value measured by the method described in the Examples below. In this specification, the front retardation is sometimes indicated as Re. The wavelength for measuring the front retardation is 550 nm unless otherwise specified. When the front retardation is a large value of about 5,000 or more, it is preferable to use the value measured by the method described in the Examples below. The front retardation can also be a value measured by irradiating light of a wavelength within the visible light wavelength range, such as the central wavelength of the selective reflection of the cholesteric liquid crystal layer, in the direction normal to the film using KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments Co., Ltd.). When selecting the measurement wavelength, the wavelength selection filter can be replaced manually, or the measured value can be converted by a program or the like.

[0016] In this specification, the term "vehicle" refers to a train, an automobile, etc. As the vehicle, an automobile having a rear window is particularly preferable.

[0017] <<<Vehicle mirror with image display function>>> The vehicle mirror with image display function can be used, for example, as a room mirror (inner mirror) of the vehicle. The vehicle mirror with image display function may have a frame, a housing, a support arm for mounting to the vehicle body, etc., in order to be used as a room mirror. Alternatively, the vehicle mirror with image display function may be molded for incorporation into a room mirror. In the vehicle mirror with image display function having the above shape, the directions that are up, down, left and right during normal use can be specified.

[0018] The vehicle mirror with image display function may be in the form of a plate or film, and may have a curved surface. The front surface of the vehicle mirror with image display function may be flat or curved. By curving the mirror and making the convex curved surface the front side, it is possible to make a wide mirror that allows a wide-angle view of the rear view, etc. Such a curved front surface can be produced by using a curved half mirror. The curvature may be in the vertical direction, the horizontal direction, or both the vertical direction and the horizontal direction. The curvature may have a radius of curvature of 500 to 3000 mm. A radius of curvature of 1000 to 2500 mm is more preferable. The radius of curvature is the radius of a circumscribing circle when the circumscribing circle is assumed to be circumscribing the curved portion in cross section.

[0019] The mirror with an image display function of the present invention includes an image display device and a half mirror. In the mirror with an image display function, an air layer or an adhesive layer may be present between the image display device and the half mirror. In this specification, the surface on the half mirror side with respect to the image display device is sometimes called the front surface. In this specification, the "vehicle mirror with image display function" may be simply referred to as the "vehicle mirror with image display function" or simply as the "mirror with image display function".

[0020] <<Image display devices>> The image display device is not particularly limited, but is preferably an image display device that forms an image by emitting (emitting) linearly polarized light, and is more preferably a liquid crystal display device. The liquid crystal display device may be a transmissive type or a reflective type, and is preferably a transmissive type. The liquid crystal display device may be any of liquid crystal display devices such as IPS (In Plane Switching) mode, FFS (Fringe Field Switching) mode, VA (Vertical Alignment) mode, ECB (Electrically Controlled Birefringence) mode, STN (Super Twisted Nematic) mode, TN (Twisted Nematic) mode, and OCB (Optically Compensated Bend) mode. When the image display device is turned off, the average reflection of visible light having a wavelength of 380 to 780 nm is preferably 30% or more, more preferably 40% or more. The reflection of visible light when the image display device is turned off may be due to a component of the image display device (such as a reflective polarizing plate or a backlight unit).

[0021] The image displayed on the image display unit of the image display device may be a still image, a moving image, or simply text information. It may also be a monochrome display such as black and white, a multicolor display, or a full-color display. A preferred example of an image displayed on the image display unit of the image display device is an image captured by a vehicle-mounted camera. It is preferable that this image be a moving image.

[0022] The image display device may, for example, exhibit a red light emission peak wavelength λR, a green light emission peak wavelength λG, and a blue light emission peak wavelength λB in the emission spectrum during white display. By having such emission peak wavelengths, full-color image display is possible. λR may be any wavelength in the range of 580-700 nm, preferably in the range of 610-680 nm. λG may be any wavelength in the range of 500-580, preferably in the range of 510-550 nm. λB may be any wavelength in the range of 400-500 nm, preferably in the range of 440-480 nm.

[0023] <<Half mirror>> The half mirror may be in the form of a plate or a film, and may have a curved surface. The half mirror may be flat or curved. A curved half mirror can be produced by using a curved front plate. The half mirror includes a reflective layer and a high Re retardation film. The reflective layer and the high Re retardation film are preferably laminated with the same main surface area. In this specification, the term "main surface" refers to the surface (front surface or back surface) of a plate-like or film-like member.

[0024] The half mirror may include other layers such as a front plate or an adhesive layer. When the half mirror includes a front plate, the order of the front plate, the high Re retardation film, and the reflective layer is preferable. When the half mirror includes a front plate, the area of ​​the main surface of the front plate may be larger than, the same as, or smaller than the area of ​​the main surface of the reflective layer. A reflective layer may be bonded to a part of the main surface of the front plate, and other types of reflective layers such as metal foil may be bonded or formed on other parts. With this configuration, an image can be displayed on a part of the mirror. On the other hand, a reflective layer may be bonded to the entire main surface of the front plate. In addition, in the mirror with an image display function, a half mirror with a main surface having the same area as the image display unit of the image display device may be used, or a half mirror with a main surface having an area larger or smaller than the image display unit of the image display device may be used. By selecting these relationships, the ratio and position of the surface of the image display unit to the entire surface of the mirror can be adjusted. Furthermore, the half mirror may be made of laminated glass, and the intermediate layer of the laminated glass may include a high Re retardation film and a reflective layer. The thickness of the half mirror is not particularly limited, but is preferably 100 μm to 20 mm, more preferably 200 μm to 15 mm, and further preferably 300 μm to 10 mm.

[0025] <High Re retardation film> The half mirror includes a high Re retardation film having a front retardation of 5000 nm or more. In this specification, the term "high Re retardation film" refers to a retardation film having a high front retardation, which is distinguished from a quarter-wave plate (retardation plate) described later. The front retardation of the high Re retardation film is preferably 6000 nm or more, and more preferably 8000 nm or more. The front retardation of the high Re retardation film is preferably as large as possible, but in consideration of manufacturing efficiency and thinning, it may be 100000 nm or less, 50000 nm or less, 40000 nm or less, or 30000 nm or less.

[0026] A high Re retardation film having a high front retardation as described above can convert polarized light generated when sunlight passes through a window glass (particularly a rear window) of a vehicle into pseudo-non-polarized light. The front phase difference that can make polarized light pseudo-unpolarized is described in paragraphs

[0022] to

[0033] of JP2005-321544A. A specific value of the front phase difference can be determined depending on the vehicle in which the mirror with image display function of the present invention is used. In particular, it may be determined depending on the magnitude of the front phase difference that occurs in sunlight transmitted through the rear window of the vehicle.

[0027] It is known that tempered glass used for vehicle windows, particularly rear windows (for example, tempered glass that is not laminated glass), has a birefringence distribution. Tempered glass is generally produced by heating float plate glass to 700°C, which is close to its softening point, and then blowing air onto the glass surface to rapidly cool it. This process causes the temperature of the glass surface to drop first, causing it to shrink and harden, while the temperature drop inside the glass is slower than at the surface, and shrinkage is also delayed, resulting in a stress distribution inside the glass, and a birefringence distribution occurs in the tempered glass even when float plate glass without birefringence is used.

[0028] Therefore, it is considered that the light incident on the front surface of the mirror with image display function, particularly through the rear window of a vehicle in which the tempered glass prepared as described above is used, will cause the above-mentioned unevenness in the mirror reflection image. In other words, if a polarized component with distribution occurs in the light incident on the front surface of the mirror with image display function due to the birefringence distribution, a difference in the intensity of the reflected light will occur due to interference between the reflected light on the front surface (outermost surface) of the mirror with image display function and the selectively reflected light on the reflective layer, which is considered to be the cause of the above-mentioned unevenness in the mirror reflection image. In the mirror with image display function of the present invention, it is presumed that the use of a high Re retardation film having a predetermined phase difference makes it possible to reduce unevenness by making the light incident on the front surface of the mirror with image display function pseudo-unpolarized before it enters the reflective layer.

[0029] In the mirror with image display function, the high Re retardation film may be provided in the order of the high Re retardation film, the reflective layer, and the image display device. In the case where the half mirror has a front plate, the front plate, the high Re retardation film, the reflective layer, and the image display device may be provided in the order. The front plate may also function as the high Re retardation film.

[0030] Examples of the high Re retardation film include birefringent materials such as plastic films and quartz plates. Examples of the plastic film include polyester films such as polyethylene terephthalate (PET), polycarbonate films, polyacetal films, and polyarylate films. For retardation films having a high retardation and mainly made of PET, reference can be made to JP2013-257579A and JP2015-102636A. Commercially available products such as Optical Cosmoshine (registered trademark) super birefringent type (Toyobo) may also be used.

[0031] A plastic film having a high retardation can generally be formed by melt extruding a resin, casting it onto a drum or the like to form a film, and stretching it uniaxially or biaxially at a stretching ratio of 2 to 5 while heating it. In order to promote crystallization and increase the strength of the film, a heat treatment called "heat setting" may be performed at a temperature higher than the stretching temperature after stretching.

[0032] It is also possible to eliminate the unevenness of the mirror reflected image by providing a high Re retardation film on the rear glass of the vehicle. In this case, the mirror with image display function does not need to include a high Re retardation film. The total of the front retardation of the retardation film provided on the rear glass of the vehicle and the front retardation of the retardation film in the mirror with image display function may achieve a front retardation of 5000 nm or more, thereby eliminating the generated polarization.

[0033] <Reflective layer> The reflective layer may be a reflective layer that can function as a semi-transmissive semi-reflective layer. That is, the reflective layer functions to display an image on the front surface of the mirror with image display function by transmitting light emitted from the image display device when an image is displayed, and on the other hand, the reflective layer functions to reflect at least a part of the light incident from the front surface direction and transmit the reflected light from the image display device when an image is not displayed, so that the front surface of the mirror with image display function becomes a mirror. The reflective layer is a polarizing reflective layer, which may be a linearly polarizing reflective layer or a circularly polarizing reflective layer.

[0034] [Linearly polarized reflective layer] Examples of the linearly polarized light reflective layer include (i) a linearly polarized light reflective plate having a multilayer structure, (ii) a polarizer in which thin films with different birefringence are laminated, (iii) a wire-grid type polarizer, (iv) a polarizing prism, and (v) a scattering anisotropic type polarizing plate.

[0035] (i) Examples of the linearly polarized light reflector having a multi-layer structure include those formed by laminating multiple layers of dielectric thin films having different refractive indices. In order to obtain a wavelength-selective reflective film, it is preferable to alternately laminate multiple layers of dielectric thin films having high refractive index and dielectric thin films having low refractive index, but the number of types is not limited to two or more, and more types may be used. The number of layers is preferably 2 to 20 layers, more preferably 2 to 12 layers, even more preferably 4 to 10 layers, and particularly preferably 6 to 8 layers. If the number of layers exceeds 20, the production efficiency decreases due to multi-layer deposition, and the object and effect of the present invention may not be achieved.

[0036] There is no particular restriction on the order of lamination of the dielectric thin films, and it can be selected appropriately according to the purpose. For example, if the refractive index of the adjacent film is high, the film with the lower refractive index is laminated first. Conversely, if the refractive index of the adjacent layer is low, the film with the higher refractive index is laminated first. The boundary between high and low refractive index is 1.8. Note that high and low refractive indexes are not absolute, and even among high refractive index materials, there may be materials with relatively high and low refractive indexes, and these may be used alternately.

[0037] Examples of materials for high refractive index dielectric thin films include Sb2O3, Sb2S3, Bi2O3, CeO2, CeF3, HfO2, La2O3, Nd2O3, and Pr6O 11 , Sc2O3, SiO, Ta2O5, TiO2, TlCl, Y2O3, ZnSe, ZnS, ZrO2, etc. Among these, Bi2O3, CeO2, CeF3, HfO2, SiO, Ta2O5, TiO2, Y2O3, ZnSe, ZnS, ZrO2 are preferred, and among these, SiO, Ta2O5, TiO2, Y2O3, ZnSe, ZnS, ZrO2 are particularly preferred.

[0038] Examples of materials for the low refractive index dielectric thin film include Al2O3, BiF3, CaF2, LaF3, PbCl2, PbF2, LiF, MgF2, MgO, NdF3, SiO2, Si2O3, NaF, ThO2, ThF4, etc. Among these, Al2O3, BiF3, CaF2, MgF2, MgO, SiO2, and Si2O3 are preferred, and Al2O3, CaF2, MgF2, MgO, SiO2, and Si2O3 are particularly preferred. In addition, there is no particular limitation on the atomic ratio of the material for the dielectric thin film, and it can be appropriately selected depending on the purpose. The atomic ratio can be adjusted by changing the atmospheric gas concentration during film formation.

[0039] The method for forming the dielectric thin film is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include vacuum deposition methods such as ion plating and ion beam, physical vapor deposition methods (PVD methods) such as sputtering, chemical vapor deposition methods (CVD methods), etc. Among these, vacuum deposition methods and sputtering methods are preferred, and sputtering methods are particularly preferred. As the sputtering method, a DC sputtering method having a high film formation rate is preferable. In the DC sputtering method, it is preferable to use a material having high electrical conductivity. In addition, methods for forming a multilayer film by sputtering include, for example, (1) a one-chamber method in which films are formed alternately or sequentially from multiple targets in one chamber, and (2) a multi-chamber method in which films are formed continuously in multiple chambers. Among these, the multi-chamber method is particularly preferable from the viewpoints of productivity and prevention of material contamination. The thickness of the dielectric thin film is preferably λ / 16 to λ, more preferably λ / 8 to 3λ / 4, and even more preferably λ / 6 to 3λ / 8, in terms of the optical wavelength order.

[0040] The light propagating through the dielectric deposition layer is partially reflected by each dielectric thin film, and these reflected lights interfere with each other to selectively transmit only light with a wavelength determined by the product of the thickness of the dielectric thin film and the refractive index of the film for light. In addition, the central transmission wavelength of the dielectric deposition layer has an angle dependency with respect to the incident light, and the transmission wavelength can be changed by changing the incident light.

[0041] (ii) As a polarizer in which thin films with different birefringences are laminated, for example, those described in JP-A-9-506837 can be used. Specifically, a wide variety of materials can be used to form polarizers when processed under conditions selected to obtain a refractive index relationship. In general, it is necessary that one of the first materials has a refractive index different from that of the second material in a selected direction. This refractive index difference can be achieved in various ways, including stretching, extrusion, or coating during or after the formation of the film. Furthermore, it is preferable that the two materials have similar rheological properties (e.g., melt viscosity) so that they can be co-extruded. A commercially available product can be used as the polarizer in which thin films with different birefringence are laminated, and an example of the commercially available product is DBEF (registered trademark) (manufactured by 3M).

[0042] (iii) A wire-grid polarizer is a polarizer that transmits one polarized light and reflects the other polarized light by using birefringence of thin metal wires. A wire grid polarizer is a polarizer that is made of metal wires arranged periodically and is mainly used as a polarizer in the terahertz wave band. For a wire grid to function as a polarizer, the wire spacing must be sufficiently smaller than the wavelength of the incident electromagnetic wave. In a wire grid polarizer, metal wires are arranged at equal intervals. The polarized light component with a polarization direction parallel to the longitudinal direction of the metal wires is reflected by the wire grid polarizer, and the polarized light component with a polarization direction perpendicular to the longitudinal direction of the metal wires is transmitted through the wire grid polarizer.

[0043] As the wire grid polarizer, a commercially available product can be used, and examples of the commercially available product include wire grid polarizing filter 50×50 and NT46-636 manufactured by Edmund Optics.

[0044] [Circularly polarized reflective layer] By using a circularly polarized light reflective layer in the half mirror, the incident light from the front side can be reflected as circularly polarized light, and the incident light from the image display device can be transmitted as circularly polarized light. Therefore, in the mirror with image display function using the circularly polarized light reflective layer, the displayed image and the mirror reflected image can be observed even through polarized sunglasses, regardless of the direction of the mirror with image display function.

[0045] Examples of circularly polarized reflective layers include a circularly polarized reflective layer including a linearly polarized reflective plate and a quarter-wave plate, and a circularly polarized reflective layer including a cholesteric liquid crystal layer (hereinafter, to distinguish between the two, they may be referred to as a "Pol λ / 4 circularly polarized reflective layer" and a "cholesteric circularly polarized reflective layer", respectively).

[0046] [Polλ / 4 circularly polarized reflective layer] In the Pol λ / 4 circularly polarized light reflective layer, the linearly polarized light reflective plate and the ¼ wavelength plate may be arranged such that the slow axis of the λ / 4 wavelength plate forms an angle of 45° with respect to the polarization reflection axis of the linearly polarized light reflective plate. The ¼ wavelength plate and the linearly polarized light reflective plate may be bonded together, for example, by an adhesive layer. By using the Pol λ / 4 circularly polarized light reflective layer with the linearly polarized light reflector disposed on the surface closer to the image display device, the light for image display from the image display device can be efficiently converted into circularly polarized light and emitted from the front surface of the mirror with image display function. When the light for image display from the image display device is linearly polarized light, the polarization reflection axis of the linearly polarized light reflector can be adjusted so that this linearly polarized light is transmitted. The thickness of the Pol λ / 4 circularly polarized light reflective layer is preferably in the range of 2.0 μm to 300 μm, and more preferably in the range of 8.0 to 200 μm. As the linearly polarized light reflecting plate, the linearly polarized light reflecting layer described above can be used. As the quarter wave plate, a quarter wave plate to be described later can be used.

[0047] [Cholesteric circularly polarized reflective layer] The cholesteric circularly polarized light reflective layer includes at least one cholesteric liquid crystal layer. The cholesteric liquid crystal layer included in the cholesteric circularly polarized light reflective layer may be any layer that exhibits selective reflection in the visible light region. The circularly polarized reflective layer may include two or more cholesteric liquid crystal layers, and may include other layers such as an alignment layer. The circularly polarized reflective layer is preferably composed of only a cholesteric liquid crystal layer. When the circularly polarized reflective layer includes multiple cholesteric liquid crystal layers, they are preferably in direct contact with adjacent cholesteric liquid crystal layers. The circularly polarized reflective layer preferably includes three or more cholesteric liquid crystal layers, such as three or four layers. The thickness of the cholesteric circularly polarized light reflective layer is preferably in the range of 2.0 μm to 300 μm, and more preferably in the range of 8.0 to 200 μm.

[0048] In this specification, the cholesteric liquid crystal layer means a layer in which a cholesteric liquid crystal phase is fixed, and may also be simply called a liquid crystal layer. It is known that a cholesteric liquid crystal phase exhibits circularly polarized light selective reflection, which selectively reflects circularly polarized light of either right-handed or left-handed sense in a specific wavelength range and selectively transmits circularly polarized light of the other sense. In this specification, circularly polarized light selective reflection is sometimes simply referred to as selective reflection.

[0049] Many films formed from compositions containing polymerizable liquid crystal compounds have been known as films containing a layer in which a cholesteric liquid crystal phase exhibiting circularly polarized light selective reflectivity is fixed, and reference can be made to these conventional techniques for the cholesteric liquid crystal layer.

[0050] The cholesteric liquid crystal layer may be a layer in which the orientation of the liquid crystal compound in the cholesteric liquid crystal phase is maintained, and typically, a layer in which a polymerizable liquid crystal compound is oriented in the cholesteric liquid crystal phase, polymerized and cured by ultraviolet irradiation, heating, etc., to form a layer with no fluidity, and at the same time, changed to a state in which the orientation form is not changed by an external field or external force. Note that, in the cholesteric liquid crystal layer, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained in the layer, and the liquid crystal compound in the layer does not need to exhibit liquid crystallinity any more. For example, the polymerizable liquid crystal compound may be polymerized by a curing reaction and no longer have liquid crystallinity.

[0051] The central wavelength λ of the selective reflection of the cholesteric liquid crystal layer depends on the pitch P (= helical period) of the helical structure in the cholesteric phase, and follows the relationship between the average refractive index n of the cholesteric liquid crystal layer and λ = n × P. The selective reflection central wavelength and half-width of the cholesteric liquid crystal layer can be calculated as follows. When the transmission spectrum of the light reflective layer (measured from the normal direction of the cholesteric liquid crystal layer) is measured using a spectrophotometer UV3150 (Shimadzu Corporation), a peak of reduced transmittance is observed in the selective reflection region. If the value of the shorter wavelength of the two wavelengths that have a transmittance height of half the height of this maximum peak is λ1 (nm) and the value of the longer wavelength is λ2 (nm), the central wavelength and half-width of the selective reflection can be expressed by the following formula. Selective reflection central wavelength = (λ1 + λ2) / 2 Half width = (λ2-λ1) The central wavelength λ of the selective reflection of the cholesteric liquid crystal layer obtained as described above usually coincides with 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. In this specification, the central wavelength of the selective reflection means the central wavelength measured from the normal direction of the cholesteric liquid crystal layer. As can be seen from the above formula, the central wavelength of selective reflection can be adjusted by adjusting the pitch of the helical structure. By adjusting the n and P values, the central wavelength λ can be adjusted to selectively reflect either right-handed or left-handed circularly polarized light of the desired wavelength.

[0052] When light is obliquely incident on the cholesteric liquid crystal layer, the central wavelength of selective reflection shifts to the short wavelength side. Therefore, it is preferable to adjust n×P so that λ calculated according to the above formula λ=n×P becomes a long wavelength with respect to the selective reflection wavelength required for image display. The central wavelength of selective reflection when a light ray passes through a cholesteric liquid crystal layer with a refractive index of n2 at an angle of θ2 with respect to the normal direction of the cholesteric liquid crystal layer (the helical axis direction of the cholesteric liquid crystal layer) is λ d Then, λ d is expressed by the following formula: λ d = n2 × P × cosθ2

[0053] Considering the above, by designing the central wavelength of the selective reflection of the cholesteric liquid crystal layer contained in the circularly polarized light reflective layer, it is possible to prevent a decrease in the visibility of the image from an oblique angle. It is also possible to intentionally reduce the visibility of the image from an oblique angle. This is useful, for example, in smartphones and personal computers, because it can prevent peeping. In addition, due to the nature of the selective reflection, the image display function-equipped mirror of the present invention may have a color tone in the image and the mirror reflection image when viewed from an oblique direction. It is also possible to prevent such a color tone by including a cholesteric liquid crystal layer having a central wavelength of selective reflection in the infrared light region in the circularly polarized light reflective layer. In this case, the central wavelength of selective reflection in the infrared light region may be specifically 780 to 900 nm, preferably 780 to 850 nm. When a cholesteric liquid crystal layer having a central wavelength of selective reflection in the infrared region is provided, it is preferably located closest to the image display device among all the cholesteric liquid crystal layers each having a central wavelength of selective reflection in the visible region.

[0054] The pitch of the cholesteric liquid crystal phase depends on the type of chiral agent used together with the polymerizable liquid crystal compound or its concentration, so the desired pitch can be obtained by adjusting these. For measuring the sense of helix and pitch, 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" edited by the Liquid Crystal Handbook Editorial Committee, Maruzen, p. 196, can be used.

[0055] In the mirror with image display function of the present invention, the circularly polarized light reflective layer preferably includes a cholesteric liquid crystal layer having a central wavelength of selective reflection in the wavelength range of red light, a cholesteric liquid crystal layer having a central wavelength of selective reflection in the wavelength range of green light, and a cholesteric liquid crystal layer having a central wavelength of selective reflection in the wavelength range of blue light. The reflective layer preferably includes, for example, a cholesteric liquid crystal layer having a central wavelength of selective reflection in the range of 400 nm to 500 nm, a cholesteric liquid crystal layer having a central wavelength of selective reflection in the range of 500 nm to 580 nm, and a cholesteric liquid crystal layer having a central wavelength of selective reflection in the range of 580 nm to 700 nm.

[0056] In addition, when the circularly polarized light reflective layer includes a plurality of cholesteric liquid crystal layers, it is preferable that the cholesteric liquid crystal layer closer to the image display device has a longer central wavelength of selective reflection. With such a configuration, it is possible to suppress oblique coloring in the image.

[0057] In particular, in a mirror with an image display function using a cholesteric circularly polarized light reflective layer that does not include a quarter-wave plate, the central wavelength of selective reflection of each cholesteric liquid crystal layer is preferably set to be 5 nm or more different from the wavelength of the emission peak of the image display device. This difference is more preferably set to 10 nm or more. By shifting the central wavelength of selective reflection from the wavelength of the emission peak for image display of the image display device, the light for image display is not reflected by the cholesteric liquid crystal layer, and the displayed image can be brightened. The wavelength of the emission peak of the image display device can be confirmed by the emission spectrum of the image display device when displaying white. The peak wavelength may be any peak wavelength in the visible light region of the emission spectrum, for example, any one or more selected from the group consisting of the emission peak wavelength λR of red light, the emission peak wavelength λG of green light, and the emission peak wavelength λB of blue light of the image display device. The central wavelength of selective reflection of the cholesteric liquid crystal layer is preferably different from any of the above-mentioned red light emission peak wavelength λR, green light emission peak wavelength λG, and blue light emission peak wavelength λB of the image display device by 5 nm or more, preferably 10 nm or more. When the circularly polarized light reflective layer includes a plurality of cholesteric liquid crystal layers, the central wavelength of selective reflection of all the cholesteric liquid crystal layers may be made different from the peak wavelength of light emitted by the image display device by 5 nm or more, preferably 10 nm or more. For example, when the image display device is a full-color display device that shows a red light emission peak wavelength λR, a green light emission peak wavelength λG, and a blue light emission peak wavelength λB in the emission spectrum during white display, the central wavelength of selective reflection of the cholesteric liquid crystal layer may be made different from any of λR, λG, and λB by 5 nm or more, preferably 10 nm or more.

[0058] By adjusting the central wavelength of the selective reflection of the cholesteric liquid crystal layer used in accordance with the emission wavelength range of the image display device and the usage mode of the circularly polarized light reflective layer, it is possible to display a bright image with good light utilization efficiency. The usage mode of the circularly polarized light reflective layer particularly includes the incident angle of light to the circularly polarized light reflective layer, the image observation direction, etc.

[0059] As each cholesteric liquid crystal layer, a cholesteric liquid crystal layer having a right or left sense of helix is ​​used. The sense of the reflected circularly polarized light of the cholesteric liquid crystal layer is the same as the sense of the helix. The multiple cholesteric liquid crystal layers may all have the same sense of helix, or may include different ones. That is, the mirror may include a cholesteric liquid crystal layer having either a right or left sense, or may include a cholesteric liquid crystal layer having both a right and left sense. However, in a mirror with an image display function including a quarter-wave plate, it is preferable that the multiple cholesteric liquid crystal layers all have the same sense of helix. In this case, the sense of helix may be determined according to the sense of the circularly polarized light obtained by outputting from the image display device and passing through the quarter-wave plate as each cholesteric liquid crystal layer. Specifically, a cholesteric liquid crystal layer having a sense of helix that transmits the circularly polarized light obtained by outputting from the image display device and passing through the quarter-wave plate may be used.

[0060] The half-width Δλ (nm) of the selective reflection band exhibiting selective reflection depends on the birefringence Δn of the liquid crystal compound and the above-mentioned pitch P, and follows the relationship Δλ = Δn × P. Therefore, the width of the selective reflection band can be controlled by adjusting Δn. Δn can be adjusted by adjusting the type of polymerizable liquid crystal compound, the mixing ratio thereof, or by controlling the temperature during alignment fixation. In order to form one type of cholesteric liquid crystal layer with the same central wavelength of selective reflection, multiple cholesteric liquid crystal layers with the same period P and the same helical sense may be laminated. By laminating cholesteric liquid crystal layers with the same period P and the same helical sense, it is possible to increase the circular polarization selectivity at a specific wavelength.

[0061] (1 / 4 wavelength plate) The mirror with an image display function using the cholesteric circularly polarized light reflective layer may further include a quarter-wave plate. By including a quarter-wave plate between the image display device and the cholesteric circularly polarized light reflective layer, it is possible to convert light from the image display device, which displays an image using linear polarization, into circularly polarized light and to make it incident on the cholesteric circularly polarized light reflective layer. Therefore, the amount of light reflected by the circularly polarized light reflective layer and returning to the image display device can be significantly reduced, making it possible to display a bright image. In addition, the use of a quarter-wave plate makes it possible to configure the cholesteric circularly polarized light reflective layer so that it does not generate a sense of circularly polarized light reflected toward the image display device, so that degradation of image display quality due to multiple reflections between the image display device and the half mirror is unlikely to occur. That is, even if the central wavelength of selective reflection of the cholesteric liquid crystal layer contained in the cholesteric circularly polarized light reflective layer is approximately the same (e.g., the difference is less than 5 nm) as the emission peak wavelength of blue light in the emission spectrum of the image display device when displaying white, the light emitted from the image display device can be transmitted to the front side without generating sense circular polarization that is reflected toward the image display side in the circularly polarized light reflective layer.

[0062] The quarter-wave plate used in combination with the cholesteric circularly polarized light reflective layer is preferably adjusted in angle so that the image becomes the brightest when it is bonded to an image display device. That is, it is preferable that the relationship between the polarization direction (transmission axis) of the linearly polarized light and the slow axis of the quarter-wave plate is adjusted so that the linearly polarized light is transmitted most efficiently, particularly for an image display device that displays an image using linearly polarized light. For example, in the case of a single-layer quarter-wave plate, the transmission axis and the slow axis preferably form an angle of 45°. After transmitting through the quarter-wave plate, the light emitted from the image display device that displays an image using linearly polarized light becomes circularly polarized light of either the right or left sense. The circularly polarized light reflective layer may be composed of a cholesteric liquid crystal layer having a twist direction that transmits circularly polarized light of the above sense.

[0063] The quarter-wave plate may be a retardation layer that functions as a quarter-wave plate in the visible light region. Examples of the quarter-wave plate include a single-layer quarter-wave plate and a wideband quarter-wave plate in which a quarter-wave plate and a half-wave retardation plate are laminated. The front retardation of the former 1 / 4 wavelength plate may be 1 / 4 the length of the emission wavelength of the image display device. Therefore, for example, when the emission wavelength of the image display device is 450nm, 530nm, or 640nm, a retardation layer with reverse dispersion such that the retardation is 112.5nm±10nm, preferably 112.5nm±5nm, more preferably 112.5nm at the wavelength of 450nm, 132.5nm±10nm, preferably 132.5nm±5nm, more preferably 132.5nm at the wavelength of 530nm, and 160nm±10nm, preferably 160nm±5nm, more preferably 160nm at the wavelength of 640nm is the most preferable as the 1 / 4 wavelength plate, but a retardation plate with small wavelength dispersion of retardation or a retardation plate with normal dispersion can also be used. Note that reverse dispersion means the property that the absolute value of the retardation becomes larger as the wavelength becomes longer, and normal dispersion means the property that the absolute value of the retardation becomes larger as the wavelength becomes shorter.

[0064] A laminated quarter-wave plate is a plate made by bonding a quarter-wave plate and a half-wave retardation plate together with their slow axes at an angle of 60°, with the half-wave retardation plate side being placed on the incident side of linearly polarized light, and with the slow axis of the half-wave retardation plate intersecting at 15° or 75° with the polarization plane of the incident linearly polarized light. This plate can be preferably used because it has good reverse dispersion properties of the retardation.

[0065] The λ / 4 wavelength plate is not particularly limited and can be appropriately selected depending on the purpose. For example, a quartz plate, 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 formed by obliquely depositing an inorganic dielectric on a support, etc. can be mentioned.

[0066] Examples of λ / 4 wave plates include: (1) a retardation plate in which a birefringent film with large retardation and a birefringent film with small retardation are laminated so that their optical axes are perpendicular to each other, as described in JP-A-5-27118 and JP-A-5-27119; and (2) a retardation plate in which a polymer film with a λ / 4 wavelength at a specific wavelength is laminated with a polymer film made of the same material and with a λ / 2 wavelength at the same wavelength, as described in JP-A-10-68816, which has a λ / 4 wavelength at a wide wavelength range. Examples of such retardation plates include a retardation plate capable of achieving a λ / 4 wavelength over a wide wavelength range by laminating two polymer films as described in JP-A-10-90521, (2) a retardation plate capable of achieving a λ / 4 wavelength over a wide wavelength range by using a modified polycarbonate film as described in WO 00 / 26705, and (4) a retardation plate capable of achieving a λ / 4 wavelength over a wide wavelength range by using a cellulose acetate film as described in WO 00 / 65384. As the λ / 4 wave plate, a commercially available product may be used, and an example of the commercially available product is PureAce (registered trademark) WR (a polycarbonate film manufactured by Teijin Limited).

[0067] The quarter-wave plate may be formed by aligning and fixing a polymerizable liquid crystal compound or a polymeric liquid crystal compound. For example, the quarter-wave plate may be formed by applying a liquid crystal composition to a temporary support, an alignment film, or a front panel surface, forming the polymerizable liquid crystal compound in the liquid crystal composition into a nematic alignment in a liquid crystal state, and then fixing the alignment by photocrosslinking or thermal crosslinking. The liquid crystal composition and the manufacturing method will be described in detail later. The quarter-wave plate may be a layer obtained by applying a composition containing a polymeric liquid crystal compound to a temporary support, an alignment film, or a front panel surface, forming the composition into a nematic alignment in a liquid crystal state, and then cooling to fix the alignment. The λ / 4 wavelength plate may be bonded to the cholesteric circularly polarized light reflective layer via an adhesive layer or may be in direct contact with the cholesteric circularly polarized light reflective layer, with the latter being preferred.

[0068] (Method of producing a quarter wave plate formed from a cholesteric liquid crystal layer and a liquid crystal composition) The following describes the materials and methods for producing the cholesteric liquid crystal layer and the quarter-wave plate formed from the liquid crystal composition. Materials used to form the quarter-wave plate include liquid crystal compositions containing polymerizable liquid crystal compounds. Materials used to form the cholesteric liquid crystal layer include liquid crystal compositions further containing chiral agents (optically active compounds). The liquid crystal composition, which is mixed with a surfactant or a polymerization initiator as necessary and dissolved in a solvent, is applied to a temporary support, a support, an alignment film, a high Re retardation film, a cholesteric liquid crystal layer serving as a lower layer, a quarter-wave plate, and the like, and after alignment aging, the liquid crystal composition is cured to fix the liquid crystal layer or the quarter-wave plate, thereby forming the cholesteric liquid crystal layer or the quarter-wave plate.

[0069] -Polymerizable liquid crystal compound- As the polymerizable liquid crystal compound, a rod-shaped liquid crystal compound may be used. Examples of rod-shaped polymerizable liquid crystal compounds include rod-shaped nematic liquid crystal compounds.As rod-shaped nematic liquid crystal compounds, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoates, cyclohexane carboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.Not only low molecular weight liquid crystal compounds but also high molecular weight liquid crystal compounds can be used.

[0070] The polymerizable liquid crystal compound is obtained by introducing a polymerizable group into a liquid crystal compound. Examples of the polymerizable group include an unsaturated polymerizable group, an epoxy group, and an aziridinyl group, and an unsaturated polymerizable group is preferable, and an ethylenically unsaturated polymerizable group is particularly preferable. The polymerizable group can be introduced into the molecule of the liquid crystal compound by various methods. The number of polymerizable groups that the polymerizable liquid crystal compound has is preferably 1 to 6, more preferably 1 to 3. Examples of the polymerizable liquid crystal compound include those described in Makromol.Chem., Vol. 190, p. 2255 (1989), Advanced Materials, Vol. 5, p. 107 (1993), U.S. Patent Nos. 4,683,327, 5,622,648, and 5,770,107, International Publications WO95 / 22586, WO95 / 24455, WO97 / 00600, WO98 / 23580, and WO98 / 52905, JP-A-1-272551, JP-A-6-16616, JP-A-7-110469, JP-A-11-80081, and JP-A-2001-328973. Two or more polymerizable liquid crystal compounds may be used in combination. The alignment temperature can be lowered by using two or more kinds of polymerizable liquid crystal compounds in combination.

[0071] Furthermore, the amount of the polymerizable liquid crystal compound added in the liquid crystal composition is preferably 80 to 99.9 mass %, more preferably 85 to 99.5 mass %, and particularly preferably 90 to 99 mass %, relative to the solid content mass of the liquid crystal composition (mass excluding the solvent).

[0072] -Chiral agents: optically active compounds- The material used to form the cholesteric liquid crystal layer preferably contains a chiral agent. The chiral agent has a function of inducing a helical structure of the cholesteric liquid crystal phase. Since the sense or pitch of the helical structure induced by the chiral compound varies depending on the compound, the chiral compound may be selected according to the purpose. The chiral agent is not particularly limited, and known compounds (for example, those described in Liquid Crystal Device Handbook, Chapter 3, Section 4-3, Chiral Agents for TN and STN, p. 199, edited by the 142nd Committee of the Japan Society for the Promotion of Science, 1989), isosorbide, and isomannide derivatives can be used. Although the chiral agent generally contains an asymmetric carbon atom, an axially asymmetric compound or a planarly asymmetric compound that does not contain an asymmetric carbon atom can also be used as the chiral agent. Examples of the axially asymmetric compound or the planarly asymmetric compound include binaphthyl, helicene, paracyclophane, and derivatives thereof. The chiral agent may have a polymerizable group. When both the chiral agent and the liquid crystal compound have a polymerizable group, a polymer having a repeating unit derived from the polymerizable liquid crystal compound and a repeating unit derived from the chiral agent can be formed by a polymerization reaction between the polymerizable chiral agent and the polymerizable liquid crystal compound. In this embodiment, the polymerizable group of the polymerizable chiral agent is preferably the same type of group as the polymerizable group of the polymerizable liquid crystal compound. Therefore, the polymerizable group of the chiral agent is also preferably an unsaturated polymerizable group, an epoxy group, or an aziridinyl group, more preferably an unsaturated polymerizable group, and particularly preferably an ethylenically unsaturated polymerizable group. The chiral agent may also be a liquid crystal compound.

[0073] The content of the chiral dopant in the liquid crystal composition is preferably 0.01 mol % to 200 mol %, and more preferably 1 mol % to 30 mol %, of the amount of the polymerizable liquid crystal compound.

[0074] -Polymerization initiator- The liquid crystal composition preferably contains a polymerization initiator. In the embodiment in which the polymerization reaction is caused to proceed by irradiation with ultraviolet light, the polymerization initiator used is preferably a photopolymerization initiator capable of initiating the polymerization reaction by irradiation with ultraviolet light. Examples of the photopolymerization initiator include α-carbonyl compounds (described in U.S. Pat. Nos. 2,367,661 and 2,367,670), acyloin ethers (described in U.S. Pat. No. 2,448,828), α-hydrocarbon-substituted aromatic acyloin compounds (described in U.S. Pat. Nos. 2,722,512), polynuclear quinone compounds (described in U.S. Pat. Nos. 3,046,127 and 2,951,758), combinations of triaryl imidazole dimers and p-aminophenyl ketones (described in U.S. Pat. No. 3,549,367), acridine and phenazine compounds (described in JP-A-60-105,667 and U.S. Pat. No. 4,239,850), and oxadiazole compounds (described in U.S. Pat. No. 4,212,970). The content of the photopolymerization initiator in the liquid crystal composition is preferably 0.1 to 20% by mass, and more preferably 0.5 to 5% by mass, based on the content of the polymerizable liquid crystal compound.

[0075] -Crosslinking agent- The liquid crystal composition may contain a crosslinking agent in order to improve the film strength and durability after curing. As the crosslinking agent, those which are cured by ultraviolet light, heat, moisture, etc. can be suitably used. The crosslinking agent is not particularly limited and can be appropriately selected according to the purpose. For example, polyfunctional acrylate compounds such as trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate; epoxy compounds such as glycidyl (meth)acrylate and ethylene glycol diglycidyl ether; aziridine compounds such as 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate] and 4,4-bis(ethyleneiminocarbonylamino)diphenylmethane; isocyanate compounds such as hexamethylene diisocyanate and biuret type isocyanate; polyoxazoline compounds having an oxazoline group in the side chain; alkoxysilane compounds such as vinyltrimethoxysilane and N-(2-aminoethyl)3-aminopropyltrimethoxysilane. In addition, a known catalyst can be used according to the reactivity of the crosslinking agent, which can improve productivity in addition to improving the film strength and durability. These may be used alone or in combination of two or more. The content of the crosslinking agent is preferably 3% by mass to 20% by mass, and more preferably 5% by mass to 15% by mass. By making the content of the crosslinking agent 3% by mass or more, it is possible to obtain the effect of improving the crosslinking density. In addition, by making the content 20% by mass or less, it is possible to maintain the stability of the formed layer.

[0076] -Orientation control agent- An alignment control agent that contributes to stable or rapid planar alignment may be added to the liquid crystal composition. Examples of the alignment control agent include fluorine (meth)acrylate polymers described in paragraphs

[0018] to

[0043] of JP-A-2007-272185, and compounds represented by formulas (I) to (IV) described in paragraphs

[0031] to

[0034] of JP-A-2012-203237. The alignment control agent may be used alone or in combination of two or more kinds.

[0077] The amount of the alignment control agent added in the liquid crystal composition is preferably 0.01 to 10% by mass, more preferably 0.01 to 5% by mass, and particularly preferably 0.02 to 1% by mass, based on the total mass of the polymerizable liquid crystal compound.

[0078] -Other additives- In addition, the liquid crystal composition may contain at least one selected from various additives such as a surfactant for adjusting the surface tension of the coating film and making the film thickness uniform, and a polymerizable monomer, etc. In addition, the liquid crystal composition may further contain a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, a coloring material, metal oxide fine particles, etc., as necessary, within a range that does not deteriorate the optical performance.

[0079] -solvent- The solvent used in the preparation of the liquid crystal composition is not particularly limited and can be appropriately selected depending on the purpose, but an organic solvent is preferably used. The organic solvent is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include ketones, alkyl halides, amides, sulfoxides, heterocyclic compounds, hydrocarbons, esters, ethers, etc. These may be used alone or in combination of two or more. Among these, ketones are particularly preferred when considering the burden on the environment.

[0080] - Coating, alignment, polymerization - The method of applying the liquid crystal composition to the temporary support, the alignment film, the high Re retardation film, the quarter-wave plate, the cholesteric liquid crystal layer as the lower layer, etc. is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include wire bar coating, curtain coating, extrusion coating, direct gravure coating, reverse gravure coating, die coating, spin coating, dip coating, spray coating, and slide coating. It can also be performed by transferring the liquid crystal composition coated separately on the support. The liquid crystal molecules are aligned by heating the applied liquid crystal composition. When forming the cholesteric liquid crystal layer, it is sufficient to achieve cholesteric alignment, and when forming the quarter-wave plate, it is preferable to achieve nematic alignment. When achieving cholesteric alignment, the heating temperature is preferably 200° C. or less, more preferably 130° C. or less. This alignment treatment can provide an optical thin film in which the polymerizable liquid crystal compound is twisted and aligned so as to have a helical axis substantially perpendicular to the film surface. During nematic alignment, the heating temperature is preferably from 50°C to 120°C, and more preferably from 60°C to 100°C.

[0081] The aligned liquid crystal compound can be further polymerized to harden the liquid crystal composition. The polymerization may be either thermal polymerization or photopolymerization by light irradiation, but photopolymerization is preferred. The light irradiation is preferably performed using ultraviolet light. The irradiation energy is 20 mJ / cm. 2 ~50J / cm 2 is preferred, and 100 mJ / cm 2 ~1,500mJ / cm 2 is more preferable. In order to promote the photopolymerization reaction, light irradiation may be performed under heating conditions or in a nitrogen atmosphere. The wavelength of the ultraviolet light to be irradiated is preferably 350 nm to 430 nm. From the viewpoint of stability, the polymerization reaction rate is preferably high, preferably 70% or more, and more preferably 80% or more. The polymerization reaction rate can be determined by measuring the consumption rate of the polymerizable functional group using an IR absorption spectrum.

[0082] The thickness of each cholesteric liquid crystal layer is not particularly limited as long as it exhibits the above-mentioned characteristics, but is preferably in the range of 1.0 μm to 150 μm, more preferably 4.0 μm to 100 μm. The thickness of the quarter wave plate formed from the liquid crystal composition is not particularly limited, but is preferably 0.2 to 10 μm, more preferably 0.5 to 2 μm.

[0083] -Temporary support, support, alignment layer- The liquid crystal composition may be applied to the surface of a temporary support or an alignment layer formed on the surface of the temporary support to form a layer. The temporary support or the temporary support and the alignment layer may be peeled off after the layer is formed. In addition, a support may be used, particularly when forming a quarter-wave plate. The support does not need to be peeled off after the layer is formed. Examples of the temporary support and the support include polyester such as polyethylene terephthalate (PET), polycarbonate, acrylic resin, epoxy resin, polyurethane, polyamide, polyolefin, cellulose derivative, silicone, or glass plate. The temporary support may be, for example, one that is peeled off after the circularly polarized reflective layer is adhered to the front plate. The temporary support may function as a protective film after the circularly polarized reflective layer is adhered to the front plate, and until the circularly polarized reflective layer is adhered to the image display device.

[0084] The alignment layer can be provided by such means as rubbing of organic compounds such as polymers (resins such as polyimide, polyvinyl alcohol, polyester, polyarylate, polyamideimide, polyetherimide, polyamide, modified polyamide, etc.), oblique deposition of inorganic compounds, formation of a layer with microgrooves, or accumulation of organic compounds (e.g., ω-tricosanoic acid, dioctadecylmethylammonium chloride, methyl stearate) by the Langmuir-Blodgett method (LB film). Furthermore, an alignment layer that generates an alignment function by applying an electric field, a magnetic field, or light irradiation may be used. In particular, it is preferable to apply a liquid crystal composition to an alignment layer made of a polymer after subjecting the layer to a rubbing treatment. The rubbing treatment can be performed by rubbing the surface of the polymer layer with paper or cloth in a certain direction. The liquid crystal composition may be applied to the surface of a temporary support without providing an alignment layer, or to the surface of a temporary support that has been subjected to a rubbing treatment. The thickness of the alignment layer is preferably 0.01 to 5 μm, and more preferably 0.05 to 2 μm.

[0085] -Laminated film of layers formed from polymerizable liquid crystal compounds- When forming a laminated film consisting of a plurality of cholesteric liquid crystal layers and a laminated film consisting of a quarter-wave plate and a plurality of cholesteric liquid crystal layers, a liquid crystal composition containing a polymerizable liquid crystal compound or the like may be applied directly to the surface of the quarter-wave plate or the previous cholesteric liquid crystal layer, and the alignment and fixing steps may be repeated, or a separately prepared quarter-wave plate, cholesteric liquid crystal layer, or a laminate thereof may be laminated using an adhesive or the like, but the former is preferred. When an adhesive layer having a thickness of usually 0.5 to 10 μm is used, interference unevenness due to uneven thickness of the adhesive layer may be observed, so that it is preferable to laminate without using an adhesive layer. In addition, in a laminated film of cholesteric liquid crystal layers, by forming the next cholesteric liquid crystal layer so as to be in direct contact with the surface of the previously formed cholesteric liquid crystal layer, the orientation direction of the liquid crystal molecules on the air interface side of the previously formed cholesteric liquid crystal layer coincides with the orientation direction of the liquid crystal molecules below the cholesteric liquid crystal layer formed thereon, and the polarization characteristics of the laminated body of cholesteric liquid crystal layers are improved.

[0086] <Front plate> The mirror with an image display function of the present invention may have a front panel. The front plate may be flat or curved. The front plate may be in direct contact with the high Re retardation film, or may be directly bonded to the high Re retardation film via an adhesive layer, etc. It is preferable that the front plate is directly bonded to the high Re retardation film via an adhesive layer, etc. The front plate is not particularly limited. A glass plate or a plastic film used in the manufacture of a normal mirror can be used as the front plate. The front plate is preferably transparent in the visible light region. Here, transparent in the visible light region means that the light transmittance in the visible light region is 80% or more, preferably 85% or more. The light transmittance used as a measure of transparency can be calculated by measuring the total light transmittance and the amount of scattered light using an integrating sphere type light transmittance measuring device and subtracting the diffuse transmittance from the total light transmittance according to the method described in JIS-K7105. In addition, it is preferable that the front plate has a small birefringence. For example, the front phase difference may be 20 nm or less, preferably less than 10 nm, and more preferably 5 nm or less. Examples of plastic films include polyesters such as polyethylene terephthalate (PET), polycarbonates, acrylic resins, epoxy resins, polyurethanes, polyamides, polyolefins, cellulose derivatives, and silicones.

[0087] The curved front panel can be produced by a plastic processing method such as injection molding. In injection molding, for example, raw plastic pellets are melted with heat, injected into a mold, and then cooled and solidified to obtain a resin product.

[0088] The film thickness of the front plate may be about 100 μm to 10 mm, preferably 200 μm to 5 mm, more preferably 500 μm to 2 mm, and further preferably 500 μm to 1000 μm.

[0089] The front plate may also serve as a high Re retardation film. That is, the front plate may be a high Re retardation film having a front retardation of 5000 nm or more. Specifically, the front plate may be a plastic plate or the like having a front retardation of 5000 nm or more, or may be a laminated glass including a high Re retardation film in an intermediate layer.

[0090] (Laminated glass containing a high Re retardation film in the intermediate layer) Laminated glass includes two glass plates and an intermediate layer therebetween. Laminated glass can generally be produced by sandwiching an interlayer sheet for laminated glass between two glass plates, repeating heat treatment and pressure treatment (treatment with a rubber roller, etc.) several times, and finally performing heat treatment under pressure using an autoclave, etc. There is no particular restriction on the thickness of the glass plates, but it may be about 0.5 mm to 5 mm, preferably 1 mm to 3 mm, and more preferably 2.0 mm to 2.3 mm.

[0091] The laminated glass containing a high Re retardation film in the intermediate layer may be formed by forming the high Re retardation film on the surface of a glass plate and then performing a normal laminated glass manufacturing process. In this case, the high Re retardation film may be attached to the glass plate with an adhesive, for example. Also, the laminated glass containing a high Re retardation film in the intermediate layer may be formed by using a laminated interlayer sheet for laminated glass containing a high Re retardation film as an intermediate sheet and carrying out the above-mentioned heat treatment and pressure treatment. The laminated interlayer sheet for laminated glass containing a high Re retardation film can be formed by laminating a high Re retardation film to the surface of a known interlayer sheet. Alternatively, it can be formed by sandwiching a high Re retardation film between two known interlayer sheets. The two interlayer sheets may be the same or different, but are preferably the same.

[0092] The intermediate film sheet may be, 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. The above resin is preferably the main component of the intermediate film sheet. The main component refers to a component that occupies 50% by mass or more of the intermediate film sheet. Among the above resins, polyvinyl butyral or ethylene-vinyl acetate copolymer is preferable, and polyvinyl butyral is more preferable. The resin is preferably a synthetic resin. Polyvinyl butyral can be obtained by acetalizing polyvinyl alcohol with butyraldehyde. The preferred lower limit of the degree of acetalization of the polyvinyl butyral is 40%, the preferred upper limit is 85%, the more preferred lower limit is 60%, and the more preferred upper limit is 75%.

[0093] The polyvinyl butyral can be prepared by acetalizing polyvinyl alcohol with butyraldehyde. Polyvinyl alcohol is usually obtained by saponifying polyvinyl acetate, and polyvinyl alcohol with a saponification degree of 80 to 99.8 mol % is generally used. The preferable lower limit of the degree of polymerization of the polyvinyl alcohol is 200, and the preferable upper limit is 3000. If it is less than 200, the penetration resistance of the obtained laminated glass may decrease, and if it exceeds 3000, the moldability of the resin film may deteriorate, and the rigidity of the resin film may become too high, resulting in poor processability. The more preferable lower limit is 500, and the more preferable upper limit is 2000.

[0094] The high Re retardation film and the intermediate film sheet can be bonded to each other by a known bonding method, but it is preferable to use a lamination process. In order to prevent the high Re retardation film and the intermediate film sheet from peeling off after processing, it is preferable to perform the lamination process under a certain degree of heating and pressure conditions. To perform stable lamination, the surface temperature of the interlayer sheet on the bonding side is preferably 50 to 130°C, and more preferably 70 to 100°C. It is preferable to apply pressure during lamination. The pressure conditions are 2.0 kg / cm 2 (0.196 MPa), and 0.5 to 1.8 kg / cm 2 (0.049 to 0.176 MPa), and more preferably 0.5 to 1.5 kg / cm 2 It is more preferable that the pressure is in the range of (0.049 to 0.147 MPa).

[0095] <Adhesive layer> The mirror with an image display function of the present invention may include an adhesive layer for bonding each layer, such as a reflective layer and a high Re retardation film, a high Re retardation film and a front plate, an image display device and a reflective layer, a quarter-wave plate and a linear polarizing reflector, etc. The adhesive layer may be formed from an adhesive. From the viewpoint of curing method, adhesives include hot melt type, heat curing type, light curing type, reaction curing type, and pressure sensitive adhesive type that does not require curing, and as materials for each, compounds such as acrylate, urethane, urethane acrylate, epoxy, epoxy acrylate, polyolefin, modified olefin, polypropylene, ethylene vinyl alcohol, vinyl chloride, chloroprene rubber, cyanoacrylate, polyamide, polyimide, polystyrene, polyvinyl butyral, etc. From the viewpoint of workability and productivity, the light curing type is preferred as the curing method, and from the viewpoint of optical transparency and heat resistance, it is preferred to use acrylate, urethane acrylate, epoxy acrylate, etc. as materials.

[0096] <How to make a half mirror> The half mirror may be produced according to the procedure of the manufacturing method of the reflective layer used. The half mirror having a front plate may be produced by forming a high Re retardation film and a reflective layer on the front plate, or by adhering a separately produced high Re retardation film and a reflective layer. For example, the half mirror may be produced by transferring a cholesteric circularly polarized reflective layer or a 1 / 4 wavelength plate and a cholesteric circularly polarized reflective layer formed on a temporary support to a high Re retardation film. For example, a cholesteric liquid crystal layer or a laminate of cholesteric liquid crystal layers may be formed on a temporary support to form a cholesteric circularly polarized reflective layer, and the surface of this circularly polarized reflective layer may be adhered to the high Re retardation film, and then the temporary support may be peeled off as necessary to obtain a half mirror. Alternatively, a 1 / 4 wavelength plate and a cholesteric liquid crystal layer may be formed in sequence on a temporary support to form a laminate of a 1 / 4 wavelength plate and a cholesteric circularly polarized reflective layer, and the surface of this cholesteric liquid crystal layer (circularly polarized reflective layer) may be adhered to the high Re retardation film, and then the temporary support may be peeled off as necessary to obtain a half mirror.

[0097] The half mirror of laminated glass containing a high Re retardation film and a reflective layer in the intermediate layer can be manufactured in the same manner as the laminated glass containing a high Re retardation film in the intermediate layer. For example, the half mirror of laminated glass may be manufactured through a normal laminated glass manufacturing process after forming a high Re retardation film and a reflective layer on the surface of a glass plate, or may be manufactured using a laminated glass laminated interlayer sheet containing a high Re retardation film and a reflective layer as an interlayer sheet. The laminated glass laminated interlayer sheet containing a high Re retardation film and a reflective layer can be formed by bonding the high Re retardation film and the reflective layer to the surface of a known interlayer sheet. Alternatively, the high Re retardation film and the reflective layer can be formed by sandwiching them between two known interlayer sheets. In the half mirror of laminated glass, the high Re retardation film and the reflective layer may be in direct contact with each other, or may be bonded via an adhesive layer.

[0098] <<<Manufacturing method for mirror with image display function>>> The mirror with image display function of the present invention is produced by disposing the half mirror so that the reflective layer side of the high Re retardation film faces the image display surface side of the image display device. When the half mirror has a front plate, the image display device, the reflective layer, the high Re retardation film and the front plate are disposed in this order. Thereafter, the image display device and the half mirror may be integrated as necessary. The image display device and the half mirror may be integrated together by connecting them with an outer frame or hinges, or by bonding. EXAMPLES

[0099] The present invention will be described in more detail below with reference to examples. The materials, reagents, amounts of substances and their ratios, operations, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the following examples.

[0100] <Preparation of Retardation Film (High Retardation Film)> [Synthesis of raw polyester] (Raw material polyester 1) As shown below, terephthalic acid and ethylene glycol were directly reacted to remove water, esterified, and then polycondensed under reduced pressure to obtain raw material polyester 1 (Sb catalyst PET) in a continuous polymerization apparatus using the direct esterification method.

[0101] (1) Esterification reaction 4.7 tons of high-purity terephthalic acid and 1.8 tons of ethylene glycol were mixed in the first esterification reactor over 90 minutes to form a slurry, which was continuously fed to the first esterification reactor at a flow rate of 3800 kg / h. Furthermore, an ethylene glycol solution of antimony trioxide was continuously fed, and the reaction was carried out at a reactor temperature of 250°C with stirring for an average residence time of about 4.3 hours. At this time, antimony trioxide was continuously added so that the amount of Sb added was 150 ppm in elemental terms.

[0102] This reaction product was transferred to a second esterification reaction tank and reacted under stirring for an average residence time of 1.2 hours at a reaction tank temperature of 250° C. An ethylene glycol solution of magnesium acetate and an ethylene glycol solution of trimethyl phosphate were continuously fed to the second esterification reaction tank so that the Mg and P addition amounts were 65 ppm and 35 ppm, respectively, in elemental equivalent values.

[0103] (2) Polycondensation reaction The esterification reaction product obtained above was continuously fed to a first polycondensation reactor, and the mixture was stirred at a reaction temperature of 270° C. and a pressure inside the reactor of 20 torr (2.67×10 -3 The polycondensation was carried out at a pressure of 1.8 MPa for an average residence time of about 1.8 hours.

[0104] The mixture was then transferred to a second condensation reactor, where it was stirred at a temperature of 276° C. and a pressure of 5 torr (6.67×10 -4 The reaction (polycondensation) was carried out under conditions of a pressure of 1.2 MPa and a residence time of about 1.2 hours.

[0105] The mixture was then transferred to a third polycondensation reactor, where the temperature inside the reactor was 278° C. and the pressure inside the reactor was 1.5 torr (2.0×10 -4The reaction (polycondensation) was carried out under conditions of a pressure of 1.5 MPa and a residence time of 1.5 hours to obtain a reaction product (polyethylene terephthalate (PET)).

[0106] Next, the resulting reaction product was discharged into cold water in the form of a strand, and immediately cut to prepare polyester pellets (cross section: major axis approximately 4 mm, minor axis approximately 2 mm, length approximately 3 mm).

[0107] The obtained polymer had an IV (intrinsic viscosity) of 0.63. This polymer was designated as Raw Material Polyester 1 (hereinafter abbreviated as PET1). The unit of intrinsic viscosity is dL / g.

[0108] (Raw material polyester 2) 10 parts by mass of dried UV absorber (2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one) and 90 parts by mass of PET1 (IV=0.63) were mixed and pelletized using a kneading extruder in the same manner as in the preparation of PET1, to obtain raw polyester 2 containing a UV absorber (hereinafter abbreviated as PET2).

[0109] [Production of polyester film] -Film forming process- 90 parts by mass of PET1 and 10 parts by mass of PET2 containing an ultraviolet absorber were dried to a moisture content of 20 ppm or less, then fed into a hopper 1 of a single-screw kneading extruder 1 having a diameter of 50 mm, and melted at 300°C in the extruder 1 (intermediate layer II). Also, PET1 was dried to a moisture content of 20 ppm or less, then charged into a hopper 2 of a single-screw kneading extruder 2 having a diameter of 30 mm, and melted at 300° C. in the extruder 2 (outer layer I, outer layer III). These two types of polymer melts were each passed through a gear pump and a filter (pore size 20 μm), and then laminated in a two-type, three-layer merging block so that the polymer extruded from extruder 1 became the middle layer (layer II) and the polymer extruded from extruder 2 became the outer layers (layers I and III), and then extruded into a sheet from a 120 mm wide die.

[0110] The molten resin was extruded from the die under the following conditions: pressure fluctuation of 1% and temperature distribution of the molten resin of 2%. Specifically, the back pressure was increased by 1% relative to the average pressure in the barrel of the extruder, and the extruder piping temperature was heated to a temperature 2% higher than the average temperature in the barrel of the extruder. The molten resin extruded from the die was extruded onto a cooling casting drum set at a temperature of 25°C, and was adhered to the cooling casting drum using an electrostatic application method. The resin was peeled off using a peeling roll arranged opposite the cooling casting drum to obtain an unstretched polyester film. At this time, the discharge amount of each extruder was adjusted so that the thickness ratio of the I layer, II layer, and III layer was 10:80:10. In addition, the conditions for extruding the molten resin from the die were changed to obtain unstretched polyester films of different thicknesses.

[0111] [Preparation of Coating Solution H] Coating solution H was prepared with the following composition. (Coating solution H) Water 56.6 parts by mass Acrylic resin (A1, solid content 28% by mass) 21.4 parts by mass Carbodiimide compound: (B1, solid content 40% by mass) 2.9 parts by mass Surfactant (E1, 1% solids aqueous solution) 8.1 parts by weight Surfactant (E2, solid content 1% by mass aqueous solution) 9.6 parts by mass Particles (F1, solid content 40% by mass) 0.4 parts by mass Lubricant (G, solid content 30% by mass) 1.0 parts by mass

[0112] Details of the compounds used are shown below. Acrylic resin: (A1) As the acrylic resin (A1), a water dispersion (solid content 28% by mass) of an acrylic resin polymerized from monomers having the following composition was used. Emulsion polymer of methyl methacrylate / styrene / 2-ethylhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid = 59 / 9 / 26 / 5 / 1 (mass%) (emulsifier: anionic surfactant), Tg = 45°C Carbodiimide compound: (B1) (Nisshinbo, Carbodilite V-02-L2) Surfactant: (E1) Sulfosuccinic acid surfactant (Rapisol A-90, manufactured by Nippon Oil & Fats) Surfactant: (E2) Polyethylene oxide surfactant (Sanyo Chemical Industries, Naroacty CL-95) Particles: (F1) Silica sol with an average particle size of 50 nm Lubricant: (G) Carnauba wax

[0113] [Formation of retardation film] (Formation of uniaxially stretched (transversely stretched) films (phase difference films A to D)) Using a reverse roll method, coating solution H having the above composition was applied to both sides of an unstretched polyester film so that the coating amount after drying was 0.12 g / m 2 The obtained film was introduced into a tenter (transverse stretching machine), and while holding the ends of the film with clips, it was heated to a temperature at which it could be stretched at a preheating temperature of 92°C, and stretched 4.0 times in the width direction (stretching speed 900% / min) to obtain a film with a width of 5 m. Next, the polyester film was heat-set and heat-relaxed while controlling the film surface temperature at 160°C, and then cooled at a cooling temperature of 50°C.

[0114] After cooling, the polyester film was divided into three widths of 1.4 m, and the chucks were trimmed. After that, both ends of each divided roll were subjected to extrusion processing (knurling) at a width of 10 mm, and then 2000 m was taken up at a tension of 18 kg / m. The divided samples were designated end A, center B, and end C from one end side, and center B was used.

[0115] (Formation of biaxially stretched (longitudinal and transverse stretched) film (phase difference film E)) The unstretched polyester film was heated to 90°C using a group of heated rolls and an infrared heater, and then stretched 3.1 times in the film running direction using a group of rolls with different peripheral speeds. After that, coating solution H was applied to both sides of the stretched film using the reverse roll method so that the coating amount after drying was 0.12 g / m on both sides. 2The film on which the coating film was formed was introduced into a tenter, and while holding the ends of the film with clips, the film was heated to a temperature at which it could be stretched at a preheating temperature of 125°C, and stretched 4.0 times in the width direction. Then, a heat setting treatment was performed so that the film surface temperature became 230°C. A retardation film E was produced in the same manner as the uniaxially stretched film except for the above. Table 1 shows the thickness and Re of the produced retardation films A to E.

[0116] [Table 1]

[0117] The Re shown in Table 1 was measured as follows. Using two polarizing plates, the orientation axis direction of the film was determined, and a 4 cm x 2 cm rectangle was cut out so that the orientation axis direction was perpendicular to the film, and used as a measurement sample. For this sample, the refractive indexes of the two perpendicular axes (Nx, Ny) and the refractive index in the thickness direction (Nz) were determined using an Abbe refractometer (Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm), and the absolute value of the difference in the refractive indexes of the two axes (|Nx-Ny|) was taken as the refractive index anisotropy (△Nxy). The film thickness d (nm) was measured using an electric micrometer (Fine Leuf Co., Ltd., Millitron 1245D) and converted to nm. The front retardation (Re) was calculated from the product (△Nxy x d) of the refractive index anisotropy (△Nxy) and the film thickness d (nm).

[0118] <Preparation of reflective layer (cholesteric liquid crystal film)> (1) Coating solution 1 for a ¼ wavelength plate, and coating solutions 2, 3, and 4 for forming a cholesteric liquid crystal layer were prepared with the compositions shown in Table 2 below.

[0119] [Table 2]

[0120] [ka] Compound 2 was produced by the method described in JP-A-2005-99248.

[0121] (2) The temporary support (280 mm x 85 mm) was a PET film (Cosmoshine A4100, thickness: 100 μm) manufactured by Toyobo Co., Ltd., and was subjected to a rubbing treatment (rayon cloth, pressure: 0.1 kgf (0.98 N), rotation speed: 1000 rpm, conveying speed: 10 m / min, number of round trips: 1). (2) Coating solution 1 was applied to the rubbed surface of the PET film using a wire bar, then dried and placed on a hot plate at 30°C. Then, the film was heated with a Fusion UV Systems Co., Ltd. electrodeless lamp "D bulb" (60 mW / cm 2 ) for 6 seconds to fix the liquid crystal phase, and a quarter-wave plate with a film thickness of 0.8 μm was obtained. Coating solution 2 was applied to the surface of the obtained layer using a wire bar, and the layer was dried and placed on a hot plate at 30° C., and then irradiated with UV light using an electrodeless lamp "D bulb" (60 mW / cm) manufactured by Fusion UV Systems Co., Ltd. 2 ) for 6 seconds to fix the cholesteric liquid crystal phase, and obtain a cholesteric liquid crystal layer with a thickness of 3.5 μm. The same process was then repeated using Coating Solution 3 and Coating Solution 4 to obtain a laminate A of a quarter-wave plate and three cholesteric liquid crystal layers (Coating Solution 3 layer: 3.0 μm, Coating Solution 4 layer: 2.7 μm). The transmission spectrum of Laminate A was measured with a spectrophotometer (JASCO Corporation, V-670), and a transmission spectrum with central wavelengths of selective reflection at 630 nm, 540 nm, and 450 nm was obtained.

[0122] <Preparation of reflective layer (reflective linear polarizer)> A linear polarizing reflector was fabricated based on the method described in JP-A-9-506837. 2,6-polyethylene naphthalate (PEN) and a 70% naphthalate / 30% terephthalate copolyester (coPEN) were synthesized in a standard polyester resin synthesis vessel using ethylene glycol as the diol. Monolayer films of PEN and coPEN were extruded and then stretched at approximately 150°C with a stretch ratio of 5:1. It was confirmed that the refractive index of PEN along the orientation axis was approximately 1.88, that along the transverse axis was 1.64, and that of the coPEN film was approximately 1.64. Alternating layers of PEN and coPEN were then formed by coextrusion using a 50-slot feedblock fed with a standard extrusion die to the thicknesses shown in Table 3(1). By repeating the above, the layers of PEN and coPEN shown in Table 3(2)-(5) were formed in order, and then layers (1)-(5) were formed repeatedly to laminate 50 layers of each, for a total of 250 layers. The stretched film was then heat-cured in an air oven at approximately 230°C for 30 seconds to obtain Laminate B.

[0123] [Table 3]

[0124] <Formation of half mirror> The retardation film A was sandwiched between polyvinyl butyral interlayer sheets for laminated glass (thickness: 380 μm) and laminated (heating temperature: 80 °C, pressure: 1.5 kg / cm 2 (0.147 MPa, conveying speed: 0.1 m / min) to produce a laminated interlayer sheet for laminated glass. Next, the laminated interlayer film sheet for laminated glass prepared above was sandwiched between two sheets of blue plate glass (250 mm x 75 mm, thickness: 0.7 mm), placed in a rubber bag, and depressurized with a vacuum pump. The temperature was then raised to 90°C under reduced pressure, held for 30 minutes, and then returned to room temperature and pressure. The sheet was then held in an autoclave for 20 minutes under conditions of a pressure of 1.3 MPa and a temperature of 130°C. The sheet was then returned to room temperature and pressure to produce a laminated glass including a high Re retardation film in the interlayer.

[0125] Next, adhesive LCR0631 manufactured by Toa Gosei Co., Ltd. was applied to the surface of the cholesteric liquid crystal layer of the laminate A with a wire bar, and then the laminate was attached to the surface of the laminated glass using a laminator. At this time, the wire bar size and the nip roll pressure of the laminator were adjusted to adjust the thickness of the adhesive layer to 2 μm. Then, the laminate was placed on a hot plate at 50° C. and an electrodeless lamp "D bulb" (60 mW / cm) manufactured by Fusion UV Systems Co., Ltd. was applied to the laminate. 2 ) for 30 seconds to adhere the two pieces together, and then the PET film was peeled off to obtain the half mirror of Example 1.

[0126] Half mirrors of Examples 2 to 4 and Comparative Examples 1 to 4 were produced in the same manner as the half mirror of Example 1, except that the high Re retardation film and the reflective layer shown in Table 3 were used instead of the retardation film A and the laminate A, respectively.

[0127] <Production of a mirror with image display function> The half mirror prepared above was attached to the surface of the image display part of an image display device (iPad (registered trademark) Retina) in the order of glass plate, retardation film, reflective layer, and image display device to prepare a mirror with an image display function. At this time, the slow axis of the 1 / 4 wavelength plate in the reflective layer was arranged at an angle of 45 degrees to the transmission axis of the image display device (polarization direction of the light emitted from the LCD).

[0128] <Evaluation of mirrors with image display function> The above-mentioned mirror with image display function was installed in the position of the inner mirror of a vehicle (model: Honda Step Wagon, 2002 model). The image of the image display device and the mirror reflection image that can be seen when sunlight is incident on the position of the inner mirror from the rear window of the vehicle were evaluated according to the following criteria. The results are shown in Table 4. [image] A: Bright image without distortion B: Images with distortion or uneven brightness, or images that are dark overall [Unevenness (due to birefringence of rear glass)] A: The diagonal light unevenness is not visible. B: Diagonal light unevenness is visible [Unevenness (due to retardation film)] A: No spotted or diagonal color unevenness is visible B: Spotted or diagonal color unevenness is visible As a result, in Examples 1 to 5, the unevenness due to the birefringence of the rear glass was not visible, and the unevenness due to the retardation film was also not visible.

[0129] [Table 4]

Claims

1. A vehicle mirror with an image display function, A half mirror and an image display device are included. the half mirror includes a high Re retardation film and a reflective layer, In the mirror with an image display function, the high Re retardation film, the reflective layer, and the image display device are arranged in this order, The high Re retardation film has a front retardation of 5000 nm or more, The mirror with an image display function, wherein the reflective layer is a linearly polarized light reflective layer or a circularly polarized light reflective layer.

2. 2. The mirror with an image display function according to claim 1, wherein the front phase difference is 7000 nm or more.

3. 3. The mirror with an image display function according to claim 1, wherein the reflective layer is a circularly polarized light reflective layer.

4. 4. The mirror with image display function according to claim 3, wherein the circularly polarized light reflective layer includes a cholesteric liquid crystal layer.

5. 5. The mirror with an image display function according to claim 4, wherein the circularly polarized light reflective layer includes three or more cholesteric liquid crystal layers.

6. Including a quarter wave plate; 6. The mirror with an image display function according to claim 4, wherein the half mirror comprises the high Re retardation film, the circularly polarized light reflective layer, and the quarter wavelength plate in this order.

7. 7. The mirror with an image display function according to claim 6, wherein the circularly polarized light reflective layer and the quarter-wave plate are in direct contact with each other.

8. 4. The mirror with an image display function according to claim 3, wherein the circularly polarized light reflective layer includes a quarter wave plate and a linearly polarized light reflective plate in this order from the high Re retardation film side.

9. the half mirror includes a front plate, 9. The mirror with an image display function according to claim 1, further comprising the front plate, the high Re retardation film, and the reflective layer in this order.

10. the half mirror includes a front plate, The front panel is a laminated glass including two glass sheets and an intermediate layer between the two glass sheets, The intermediate layer includes the high Re retardation film. The mirror with an image display function according to any one of claims 1 to 8.

11. The half mirror is a laminated glass including two glass plates and an intermediate layer between the two glass plates, The intermediate layer includes the high Re retardation film and the reflective layer. The mirror with an image display function according to any one of claims 1 to 8.

Images