JP6479699B2 - Mirror with image display function for vehicle and method for manufacturing the same - Google Patents

Description

  The present invention relates to a mirror with an image display function for a vehicle including an image display unit capable of displaying a captured image around the vehicle and a method for manufacturing the same.

  Conventionally, there has been proposed a mirror with an image display function in which a half mirror composed of a reflective polarizing plate or the like is disposed on an image display surface of an image display device (see Patent Document 1). When an image is displayed on the image display unit, the mirror with the image display function is visually recognized by the user through the half mirror.

  On the other hand, when an image is not displayed on the image display unit, the half mirror acts as a mirror surface, and a reflected image based on the reflected light from the mirror surface is visually recognized by the user.

  In Patent Document 2 and Patent Document 3, it is proposed that a captured image obtained by photographing the periphery of a vehicle is displayed on an image display unit of a mirror with an image display function as described above to be used as a rearview mirror.

JP 2011-45427 A Special table 2011-527773 gazette JP-T 2009-529452

  The mirror with an image display function of Patent Document 1 includes a transparent substrate and a polarizing reflection plate formed on the transparent substrate, and is configured by arranging the polarizing reflection plate and the transparent substrate in this order from the image display unit side. However, an optical compensation layer such as a quarter-wave plate or a high retardation plate is further provided so that a clear image and mirror reflection image can be visually recognized without direction dependency even when the user uses polarized sunglasses. It is conceivable to provide it.

  FIG. 10 shows an example of a mirror with an image display function in which a quarter wavelength plate is further provided for the mirror with an image display function as described in Patent Document 1. A mirror 100 with an image display function shown in FIG. 10 is configured by arranging a quarter-wave plate 104 and a linearly polarized light reflection layer 103 in this order from the front plate 105 made of a transparent substrate toward the image display unit 101 side. It is configured.

  Here, the quarter-wave plate 104 and the front plate 105, and the linearly polarized reflection layer 103 and the quarter-wave plate 104 are an OCR (Optically Clear Resin) (optically transparent resin) or OCA (Optically Clear Adhesive) sheet, respectively. It is conceivable to bond using an optical transparent adhesive sheet or the like.

  However, as a result of examination by the inventors, it has been found that, for example, when bonding is performed using OCR, a large distortion occurs in the mirror surface due to uneven application of OCR, and this appears as distortion of the reflected image. In addition, when the OCA sheet is used for adhesion, coating unevenness such as OCR does not occur, but the two-layer OCA sheets 106 and 107 are attached to the front plate 105 serving as a reference surface for ensuring flatness. It was found that the distortion caused by the orange-peeled irregularities of the OCA sheets 106 and 107 appears in the reflected image.

  In view of the above problems, the present invention is a vehicle capable of visually recognizing a clear image and a mirror reflection image without direction dependency even when a user uses polarized sunglasses or the like, and suppressing distortion of the reflection image. An object of the present invention is to provide a mirror with an image display function and a method for manufacturing the same.

  The mirror with an image display function for a vehicle according to the present invention is a mirror with an image display function for a vehicle including an image display unit capable of displaying a captured image of the periphery of the vehicle. A dichroic polarization reflection layer on which the displayed imaged image light is incident, a front plate made of glass or plastic, and an optical compensation layer are arranged, and the dichroic polarization reflection layer and the front plate are a single layer first. It is characterized by being adhered by an adhesive layer, and the front plate and the optical compensation layer are adhered by a single second adhesive layer.

  In the vehicle image display function-equipped mirror of the present invention, the thickness of the first adhesive layer is preferably 10 μm or more and 25 μm or less.

  In the mirror with an image display function for vehicles of the present invention, the first adhesive layer is preferably an optical transparent adhesive sheet.

  In the above-described mirror with an image display function for a vehicle of the present invention, the thickness of the second adhesive layer is preferably 10 μm or more and 25 μm or less.

  In the mirror with an image display function for a vehicle of the present invention, the second adhesive layer is preferably an optical transparent adhesive sheet.

  In the above-described mirror with an image display function for a vehicle according to the present invention, the dichroic polarization reflection layer can be a linear polarization reflection layer.

  In the above-described mirror with an image display function for a vehicle of the present invention, the linearly polarized light reflecting layer may have a multilayer structure in which thin films having different birefringence are alternately laminated.

  In the above-described mirror with an image display function for a vehicle according to the present invention, the optical compensation layer can be a quarter wavelength plate.

  In the above-described mirror with an image display function for a vehicle of the present invention, the optical compensation layer can be a high retardation plate.

  In the mirror with a vehicle image display function of the present invention, the optical compensation layer can be composed of a quarter wavelength plate and a high retardation plate.

  In the above-described mirror with an image display function for a vehicle according to the present invention, the dichroic polarization reflection layer can be a circular polarization reflection layer.

  Further, in the vehicle image display function mirror of the present invention, when the dichroic polarization reflection layer is a circular polarization reflection layer, the optical compensation layer can be a high retardation plate.

  Further, in the vehicle image display function mirror of the present invention, when the dichroic polarization reflection layer is a circular polarization reflection layer, the optical compensation layer can be a quarter wavelength plate.

  In the vehicle image display function mirror of the present invention, a hard coat treatment of 2H or more can be applied to the surface of the optical compensation layer opposite to the front plate side.

  In the above-described mirror with an image display function for a vehicle of the present invention, a protective plate made of glass or plastic can be provided on the side opposite to the front plate side of the optical compensation layer.

  A manufacturing method of a mirror with an image display function for a vehicle of the present invention is a manufacturing method of a mirror with an image display function for a vehicle according to the present invention, wherein a sheet-like second adhesive layer is formed on an optical compensation layer, A front plate is laminated on the second adhesive layer, a sheet-like first adhesive layer is formed on the front plate, and a dichroic polarizing reflection layer is laminated on the first adhesive layer. Features.

  In the method for manufacturing a mirror with an image display function for a vehicle according to the present invention, the thickness of the first adhesive layer is preferably 10 μm or more and 25 μm or less.

  Moreover, in the manufacturing method of the mirror with an image display function for vehicles of the said invention, it is preferable to use the transparent adhesive sheet for optics as a 1st adhesion layer.

  In the method for manufacturing a mirror with an image display function for a vehicle according to the present invention, the thickness of the second adhesive layer is preferably 10 μm or more and 25 μm or less.

  Moreover, in the manufacturing method of the mirror with an image display function for vehicles of the said invention, it is preferable to use the transparent adhesive sheet for optics as a 2nd adhesion layer.

  According to the vehicle image display function mirror of the present invention and the method for manufacturing the same, the dichroic polarization reflection layer, the front plate, and the optical compensation layer are arranged in this order from the image display unit side. The front plate is bonded by a single first adhesive layer, and the front plate and the optical compensation layer are bonded by a single second adhesive layer. In this way, the dichroic polarizing reflection layer and the optical compensator are bonded to the front plate by a single adhesive layer, respectively, so that even when the user is using polarized sunglasses, etc., it is clear without direction dependency. An image and a mirror reflection image can be visually recognized, and distortion of the reflection image can be suppressed.

The figure which shows schematic structure of the room mirror for vehicles using one Embodiment of the mirror with an image display function for vehicles of this invention The perspective view which shows schematic structure of one Embodiment of the mirror with an image display function for vehicles of this invention. Sectional drawing which shows schematic structure of 1st Embodiment of the mirror with a vehicle image display function of this invention. The figure for demonstrating each process of the manufacturing method of the mirror with a vehicle image display function of 1st Embodiment. Sectional drawing which shows the modification of the mirror with a vehicle image display function of 1st Embodiment Sectional drawing which shows schematic structure of 2nd Embodiment of the mirror with an image display function for vehicles of this invention. Sectional drawing which shows the modification of the mirror with a vehicle image display function of 1st Embodiment The figure for demonstrating each process of the manufacturing method of the mirror with a vehicle image display function of 2nd Embodiment. Sectional drawing which shows the modification of the mirror with a vehicle image display function of 2nd Embodiment Sectional drawing which shows schematic structure of the mirror with the image display function for vehicles of a comparative example

  Hereinafter, a first embodiment of a vehicle image display function mirror of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a vehicular room mirror using a vehicular image display function mirror according to the present embodiment. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value. Further, in this specification, for example, an angle such as “45 °”, “parallel”, “vertical” or “orthogonal” is within a range where the difference from the strict angle is less than 5 degrees unless otherwise specified. It means that there is. The difference from the exact angle is preferably less than 4 degrees, and more preferably less than 3 degrees. In the present specification, “(meth) acrylate” is used in the meaning of “one or both of acrylate and methacrylate”.

  The room mirror 1 of this embodiment is provided with the mirror 10 with a vehicle image display function and the rectangular-shaped frame 11 to which the mirror 10 with a vehicle image display function was attached, as shown in FIG. In the present embodiment, the vehicle image display function-equipped mirror 10 is used as a room mirror in the vehicle. However, the present invention is not limited thereto, and may be used as a side mirror or a mirror attached to another vehicle. Good.

  As shown in FIG. 2, the mirror 10 with an image display function for a vehicle includes an image display unit 20 that can display a captured image around the vehicle, and circularly polarized light on which the captured image light displayed on the image display unit 20 is incident. The reflection part 12 is provided.

  The image display unit 20 can display a photographed image photographed by, for example, a CCD (Charge Coupled Device) camera or a CMOS (Complementary Metal Oxide Semiconductor) camera that photographs the periphery of the rear and / or side of the vehicle. is there. Specifically, a liquid crystal display device is preferable. The image display unit 20 is preferably an image display device that forms an image by emitting (emitting light) linearly polarized light.

  The image display unit 20 may be a transmissive display device or a reflective display device, and is particularly preferably a transmissive display device. When a liquid crystal display device is used as the image display unit 20, the liquid crystal display device includes an IPS (In-Plane Switching) mode, an FFS (Fringe Field Switching) mode, a VA (vertical alignment) mode, an ECB (Electrically Controlled Birefringence) mode, an STN. Any liquid crystal display device such as a (Super Twisted Nematic) mode, a TN (Twisted Nematic) mode, and an OCB (Optically Compensated Bend) mode may be used.

  The image displayed on the image display unit 20 may be a still image of a captured image or a moving image, and simple character information different from the captured image may be displayed on the image display unit 20. In addition, any of mono color display, multi color display, and full color display may be used.

  As shown in FIG. 2, the circularly polarized light reflection unit 12 is provided on the image display surface 20 a side of the image display unit 20.

  And the circularly polarized light reflection part 12 functions as a semi-transmissive semi-reflective layer in the mirror 10 with an image display function for vehicles. That is, when the captured image is displayed on the image display unit 20, the circularly polarized light reflection unit 12 transmits the emitted light (captured image light) from the image display unit 20, thereby providing a mirror with an image display function for vehicles. 10 so that a photographed image is displayed on the front surface.

  On the other hand, when the captured image is not displayed on the image display unit 20, the circularly polarized light reflection unit 12 receives incident light from the side opposite to the image display unit 20 side (from the arrow S direction side shown in FIG. 2). It reflects and functions so that the front surface of the mirror 10 with a vehicle image display function becomes a mirror. With such a function, the user A can visually recognize the captured image when the captured image is displayed on the image display unit 20, and the vehicle image when the image display unit 20 is not displayed. An image based on the reflected light reflected from the front surface of the mirror 10 with a display function can be viewed.

  FIG. 3 is a sectional view taken along line B-C of the vehicle image display function-equipped mirror 10 shown in FIG. As shown in FIG. 3, the circularly polarized light reflecting portion 12 includes a linearly polarized light reflecting layer 21, a front plate 22 made of glass or plastic, and a quarter wavelength plate 23. In this embodiment, the linearly polarized light reflecting layer 21 corresponds to a dichroic polarized light reflecting layer, and the quarter wavelength plate 23 corresponds to an optical compensation layer.

  The linearly polarized light reflection layer 21, the front plate 22, and the quarter wavelength plate 23 are arranged in this order from the image display unit 20 side. That is, the linearly polarized light reflecting layer 21 is disposed on the image display unit 20 side with respect to the front plate 22, and the quarter wavelength plate 23 is disposed on the opposite side of the image display unit 20 side with respect to the front plate 22.

  With such a configuration, the circularly polarized light reflecting portion 12 functions as a semi-transmissive and semi-reflective layer. However, as shown in FIG. 3, the mirror surface M is formed on the surface 21 a on the front plate 22 side of the linearly polarized light reflecting layer 21. .

  The linearly polarized light reflection layer 21 and the front plate 22 are bonded by a single first adhesive layer 24, and the front plate 22 and the quarter-wave plate 23 are bonded by a single second adhesive layer 25. ing.

  Here, the adhesion by the single first adhesive layer 24 or the second adhesive layer 25 is between the linearly polarized light reflecting layer 21 and the front plate 22 or between the front plate 22 and the quarter-wave plate 23. It means that only one adhesive layer is arranged without including any adhesive layer other than the first adhesive layer 24 or the second adhesive layer 25. The first adhesive layer 24 itself and the second adhesive layer 25 itself may be formed from a plurality of layers.

  In the mirror 10 with an image display function for a vehicle of the present embodiment, the linearly polarized light reflection layer 21 and the front plate 22 are bonded by a single first adhesive layer 24, and the image display unit 20 side with respect to the front plate 22. A quarter-wave plate 23 is arranged on the opposite side to the above. Therefore, the light emitted from the quarter-wave plate 23 becomes circularly polarized light, and even when the user is using polarized sunglasses, a clear image and a mirror reflection image can be visually recognized without direction dependency, and as shown in FIG. Compared with a mirror with an image display function having a laminated structure, the distortion of the reflected image can be suppressed. Further, since the front plate 22 and the quarter-wave plate 23 are also bonded by the single second adhesive layer 25, the distortion of the reflected image can be further suppressed.

  As the first adhesive layer 24 and the second adhesive layer 25, an OCA sheet (optical transparent adhesive sheet) can be used. The OCA sheet is a double-sided pressure-sensitive adhesive sheet in which an optically transparent pressure-sensitive adhesive is formed in a sheet shape, and is sandwiched between two release sheets. When used as the first pressure-sensitive adhesive layer 24 and the second pressure-sensitive adhesive layer 25, the release sheet described above is peeled off from the pressure-sensitive adhesive layer.

  Since the OCA sheet is sandwiched between two release sheets, it is easy to handle. The OCA sheet is a gel-like soft adhesive sheet and does not require a curing step like OCR, and there is no change in properties before and after bonding. On the other hand, OCR requires a process of curing with heat, moisture or ultraviolet light after being applied to the object to be bonded, and is a liquid before being applied and bonded, and is cured after being bonded. It becomes solid by the process.

  Therefore, the OCA sheet can be used in a process of bonding members wound in a roll shape, and is suitable for bonding large-area members together. Compared with the case where a large-area member is bonded by OCR, the equipment can be made smaller.

  Commercially available products can be used as the OCA sheet. For example, the product name: 81/82 series (manufactured by 3M Japan), the product name: KF4 series (manufactured by New Tac Kasei Co., Ltd.), the product name: FWD series (Nikei Kako Co., Ltd.) and trade name: TD series (Yodogawa Paper Co., Ltd.) can be used.

  In addition, the thickness of the first adhesive layer 24 and the second adhesive layer 25 is desirably 10 μm or more and 25 μm or less. For example, when an OCA sheet is used as the first pressure-sensitive adhesive layer 24 and the second pressure-sensitive adhesive layer 25, when the thickness is 10 μm or more, a part of the pressure-sensitive adhesive layer is not peeled from the release sheet when the release sheet is peeled off. A uniform pressure-sensitive adhesive layer can be formed without remaining, and it is easy to handle without wrinkling at the time of bonding. Therefore, it is preferable that the thickness of the 1st adhesion layer 24 and the 2nd adhesion layer 25 shall be 10 micrometers or more. Moreover, when the thickness of the 1st adhesion layer 24 and the 2nd adhesion layer 25 shall be 25 micrometers or less, the orange peel-like unevenness | corrugation of the surface of an OCA sheet is not conspicuous, and from the mirror 10 with an image display function for vehicles. Distortion due to the unevenness of the reflected image can be further suppressed. Therefore, it is preferable that the thickness of the 1st adhesion layer 24 and the 2nd adhesion layer 25 shall be 25 micrometers or less.

  In the circularly polarized light reflecting portion 12, the linearly polarized light reflecting layer 21 and the quarter wavelength plate 23 are bonded so that the slow axis of the quarter wavelength plate 23 is 45 ° with respect to the polarized light reflecting axis of the linearly polarized light reflecting layer 21. You just need to match. Further, when the photographic image light emitted from the image display unit 20 is linearly polarized light, the polarization reflection axis of the linearly polarized light reflecting layer 21 may be adjusted so as to transmit this linearly polarized light. The thickness of the circularly polarized light reflecting portion 12 is preferably 2.0 μm to 300 μm, and more preferably 8.0 μm to 200 μm.

  As the linearly polarized light reflecting layer 21, for example, a dielectric multilayer film, a polarizer in which thin films having different birefringence are laminated, a wire grid polarizer, a polarizing prism, or a scattering anisotropic polarizing plate can be used.

Examples of the dielectric multilayer film include a multilayer film in which a plurality of dielectric materials having different refractive indexes are laminated on a support from an oblique direction by vacuum deposition or sputtering. In order to obtain a wavelength selective reflection film having a linear polarization function, it is preferable that a plurality of optically anisotropic dielectric thin films and optically isotropic dielectric thin films are alternately laminated. This is produced, for example, by alternately laminating a layer from an oblique direction and a layer from a vertical direction on a support. Lamination may be performed with one kind of material or with two or more kinds of materials. The number of stacked layers is preferably 10 to 500 layers, more preferably 50 to 300 layers. Examples of the material to be laminated include Ta ₂ O ₅ , TiO ₂ , SiO ₂ , and LaTiO ₃ .

  The method for forming the dielectric multilayer film is not particularly limited and may be appropriately selected depending on the intended purpose. For example, vacuum deposition methods such as ion plating and ion beam, physical vapor deposition methods such as sputtering ( PVD (Physical Vapor Deposition) method) and chemical vapor deposition (CVD (Chemical Vapor Deposition) method). Among these, the vacuum evaporation method and the sputtering method are preferable, and the sputtering method is particularly preferable.

  As a polarizer in which thin films having different birefringence are laminated, for example, those described in JP-T-9-506837 can be used. Specifically, when processed under conditions selected to obtain a refractive index relationship, a polarizer can be formed using a wide variety of materials. In general, one of the first materials needs to have a different refractive index than the second material in the chosen direction. This difference in refractive index can be achieved in a variety of ways, including stretching, extrusion, or coating during or after film formation. Furthermore, it is preferred to have similar rheological properties (eg, melt viscosity) so that the two materials can be coextruded. Commercially available products can be used as the polarizers laminated with thin films having different birefringence, such as trade names manufactured by 3M: DBEF (Dual Brightness Enhancement Film) (registered trademark), APF (Advanced Polarizer Film), and the like. It is done.

  A wire grid type polarizer is a polarizer that transmits one of polarized light and reflects the other by birefringence of a thin metal wire. The wire grid polarizer is a periodic arrangement of metal wires, and is mainly used as a polarizer in the terahertz wave band. In order for the wire grid to function as a polarizer, the wire interval needs to be sufficiently smaller than the wavelength of the incident electromagnetic wave. In the wire grid polarizer, metal wires are arranged at equal intervals. The polarization component in the polarization direction parallel to the longitudinal direction of the metal wire is reflected by the wire grid polarizer, and the polarization component in the perpendicular polarization direction is transmitted through the wire grid polarizer. A commercial item can be used as a wire grid type polarizer, for example, the wire grid polarizing filter 50x50 by NT, and NT46-636 etc. can be used.

  The quarter wave plate 23 is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a quartz plate, a stretched polycarbonate film, a stretched norbornene polymer film, and strontium carbonate. A transparent film containing inorganic particles having birefringence and oriented, or a thin film obtained by obliquely depositing an inorganic dielectric on a support can be used.

  Examples of the quarter-wave plate 23 include a birefringent film having a large retardation, a birefringent film having a small retardation, and the like described in JP-A-5-27118 and JP-A-5-27119. Are made of the same material as the retardation film laminated in such a manner that their optical axes are orthogonal to each other, a polymer film described in JP-A-10-68816, which has a quarter wavelength at a specific wavelength. A retardation film capable of obtaining a quarter wavelength in a wide wavelength region by laminating a polymer film having a half wavelength at the same wavelength, two polymers described in JP-A-10-90521 A retardation plate capable of achieving a quarter wavelength in a wide wavelength region by laminating films, described in International Publication No. 2000/26705 pamphlet A quarter wave can be achieved in a wide wavelength region using a phase difference plate that can achieve a quarter wavelength in a wide wavelength region using a conductive polycarbonate film, or a cellulose acetate film described in International Publication No. 2000/65384 pamphlet. A retardation plate that can be used can be used. As the quarter wavelength plate, a commercially available product can be used, for example, trade name: Pure Ace WR (manufactured by Teijin Ltd.).

  The quarter wavelength plate 23 may be formed by aligning and fixing a polymerizable liquid crystal compound or a polymer liquid crystal compound. For example, for a quarter-wave plate, a liquid crystal composition is applied to a support or an alignment film, and a polymerizable liquid crystal compound in the liquid crystal composition is formed into a nematic alignment in a liquid crystal state and then fixed by photocrosslinking or thermal crosslinking. Can be formed. The quarter-wave plate is formed by applying a liquid crystal composition on a surface of a support, an alignment film, or a front plate to form a nematic alignment in a liquid crystal state, and then cooling the composition. It may be a layer obtained by fixing the orientation.

  The liquid crystal composition contains a polymerizable liquid crystal compound, and may further contain a surfactant, a polymerization initiator, or the like as necessary. A liquid crystal composition to which a solvent or the like is added if necessary is applied to a support, an alignment film, or a retardation layer to be a lower layer, and after the alignment aging, the liquid crystal composition is fixed by curing and the quarter-wave plate 23. Can be formed.

  A rod-like liquid crystal compound may be used as the polymerizable liquid crystal compound. Examples of the rod-like polymerizable liquid crystal compound include a rod-like nematic liquid crystal compound. Examples of rod-like nematic liquid crystal compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Not only low-molecular liquid crystal compounds but also high-molecular liquid crystal compounds can be used.

  The polymerizable liquid crystal compound can be obtained by introducing a polymerizable group into the liquid crystal compound. Examples of the polymerizable group include an unsaturated polymerizable group, an epoxy group, and an aziridinyl group, preferably an unsaturated polymerizable group, and particularly preferably an ethylenically unsaturated polymerizable group. The polymerizable group can be introduced into the molecule of the liquid crystal compound by various methods. The number of polymerizable groups possessed by the polymerizable liquid crystal compound is preferably 1 to 6, more preferably 1 to 3. Examples of polymerizable liquid crystal compounds are described in Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. Nos. 4,683,327, 5,622,648 and 5,770,107, International Publication No. 1995/22586. Pamphlet, International Publication No. 1995/24455, International Publication No. 1997/00600, International Publication No. 1998/23580, International Publication No. 1998/52905, JP-A-1-272551, 6-16616 And the compounds described in JP-A-7-110469, JP-A-11-80081, JP-A-2001-328773, and the like. Two or more kinds of polymerizable liquid crystal compounds may be used in combination. When two or more kinds of polymerizable liquid crystal compounds are used in combination, the alignment temperature can be lowered.

  Moreover, it is preferable that the addition amount of the polymeric liquid crystal compound in a liquid-crystal composition is 80-99.9 mass% with respect to solid content mass (mass except a solvent) of a liquid-crystal composition, and 85-99. More preferably, it is 5 mass%, and it is especially preferable that it is 90-99 mass%.

  The liquid crystal composition preferably contains a polymerization initiator. In the embodiment in which the polymerization reaction is advanced by ultraviolet irradiation, the polymerization initiator to be used is preferably a photopolymerization initiator that can start the polymerization reaction by ultraviolet irradiation. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatics. Group acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketone (US patents) No. 3549367), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850), oxadiazole compounds (US Pat. No. 4,221,970), and the like. .

The content of the photopolymerization initiator in the liquid crystal composition is preferably 0.1 to 20% by mass, and preferably 0.5 to 5% by mass with respect to the content of the polymerizable liquid crystal compound. Further preferred.

  The liquid crystal composition may optionally contain a crosslinking agent in order to improve the film strength after curing and improve the durability. As the cross-linking agent, one that can be cured by ultraviolet rays, heat, moisture, or the like can be suitably used. There is no restriction | limiting in particular as a crosslinking agent, According to the objective, it can select suitably, For example, polyfunctional acrylate compounds, such as a trimethylol propane tri (meth) acrylate and pentaerythritol tri (meth) acrylate; Glycidyl (meth) acrylate , Epoxy compounds such as ethylene glycol diglycidyl ether; aziridine compounds such as 2,2-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], 4,4-bis (ethyleneiminocarbonylamino) diphenylmethane; hexa Isocyanate compounds such as methylene diisocyanate and biuret type isocyanate; polyoxazoline compound having an oxazoline group in the side chain; vinyltrimethoxysilane, N- (2-aminoethyl) 3-aminopro Alkoxysilane compounds such as Le trimethoxysilane. Moreover, a well-known catalyst can be used according to the reactivity of a crosslinking agent, and productivity can be improved in addition to membrane strength and durability improvement. These may be used individually by 1 type and may use 2 or more types together. 3 mass%-20 mass% are preferable, and, as for content of a crosslinking agent, 5 mass%-15 mass% are more preferable. When the content of the crosslinking agent is less than 3% by mass, the effect of improving the crosslinking density may not be obtained, and when it exceeds 20% by mass, the stability may be lowered.

  An alignment control agent that contributes to stable or rapid planar alignment may be added to the liquid crystal composition. Examples of the orientation control agent include fluorine (meth) acrylate polymers described in paragraphs [0018] to [0043] of JP-A-2007-272185, and paragraphs [0031] to [0034] of JP-A-2012-203237. And compounds represented by the formulas (I) to (IV) described in the above. In addition, as an orientation control agent, 1 type may be used independently and 2 or more types may be used together.

  The addition amount of the alignment control agent in the liquid crystal composition is preferably 0.01% by mass to 10% by mass, more preferably 0.01% by mass to 5% by mass with respect to the total mass of the polymerizable liquid crystal compound. 0.02% by mass to 1% by mass is particularly preferable.

  In addition, the liquid crystal composition may contain at least one selected from a surfactant for adjusting the surface tension of the coating film to make the film thickness uniform, and various additives such as a polymerizable monomer. . Further, in the liquid crystal composition, if necessary, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, a coloring material, metal oxide fine particles, and the like may be added within a range that does not deteriorate the optical performance. Can be added.

  There is no restriction | limiting in particular as a solvent used for preparation of a liquid-crystal composition, Although it can select suitably according to the objective, An organic solvent is used preferably. The organic solvent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include ketones, alkyl halides, amides, sulfoxides, heterocyclic compounds, hydrocarbons, esters and ethers. Can be mentioned. These may be used individually by 1 type and may use 2 or more types together. Among these, ketones are particularly preferable in consideration of environmental load.

  The method of applying the liquid crystal composition to the support or alignment film is not particularly limited and can be appropriately selected depending on the purpose. For example, the wire bar coating method, curtain coating method, extrusion coating method, direct gravure coating Method, reverse gravure coating method, die coating method, spin coating method, dip coating method, spray coating method and slide coating method. It can also be carried out by transferring a liquid crystal composition separately coated on a support. The liquid crystal molecules are aligned by heating the applied liquid crystal composition. Nematic orientation is preferred. The heating temperature is preferably 50 ° C to 120 ° C, more preferably 60 ° C to 100 ° C.

The aligned liquid crystal compound can be further polymerized to cure the liquid crystal composition. The polymerization may be either thermal polymerization or photopolymerization by light irradiation, but photopolymerization is preferred. It is preferable to use ultraviolet rays for light irradiation. The irradiation energy is preferably ^{20mJ / cm 2 ~50J / cm 2} , 100mJ / cm 2 ~1,500mJ / cm 2 is more preferable. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions or in a nitrogen atmosphere. The irradiation ultraviolet wavelength is preferably 350 nm to 430 nm. The polymerization reaction rate is preferably as high as possible from the viewpoint of stability, preferably 70% or more, and more preferably 80% or more. The polymerization reaction rate can be determined by using the IR (Infrared) absorption spectrum for the consumption ratio of the polymerizable functional group.

  Although the thickness of the quarter wavelength plate formed from a liquid-crystal composition is not specifically limited, Preferably it is 0.2-10 micrometers, More preferably, it is 0.5-2 micrometers.

  The liquid crystal composition may be applied to the support or the surface of the alignment layer formed on the support surface. The support may be a temporary support that is peeled off after layer formation. Examples of the support include polyester such as polyethylene terephthalate (PET), polycarbonate, acrylic resin, epoxy resin, polyurethane, polyamide, polyolefin, cellulose derivative, silicone, and glass plate.

  The alignment layer has a rubbing treatment of organic compounds such as polymers (resins such as polyimide, polyvinyl alcohol, polyester, polyarylate, polyamideimide, polyetherimide, polyamide and modified polyamide), oblique deposition of inorganic compounds, and microgrooves. It can be provided by means such as layer formation or accumulation of organic compounds (eg ω-tricosanoic acid, dioctadecylmethylammonium chloride and methyl stearylate) by the Langmuir-Blodgett method (LB film). Further, an alignment layer that generates an alignment function by application of an electric field, application of a magnetic field, or light irradiation may be used. In particular, the alignment layer made of a polymer is preferably subjected to a rubbing treatment and then a liquid crystal composition is applied to the rubbing treatment surface. The rubbing treatment can be performed by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth. You may apply | coat a liquid-crystal composition to the surface of a support body which does not provide an alignment layer, or the surface which carried out the rubbing process of the support body. The thickness of the alignment layer is preferably 0.01 to 5 μm, and more preferably 0.05 to 2 μm.

  As the front plate 22, a glass plate or a plastic plate used for manufacturing a normal mirror can be used. The front plate 22 is preferably transparent in the visible light region and has a small birefringence. Examples of the plastic plate include polyester such as polyethylene terephthalate (PET), polycarbonate, acrylic resin, epoxy resin, polyurethane, polyamide, polyolefin, cellulose derivative, and silicone. The film thickness of the front plate 22 may be about 100 μm to 10 mm, preferably 200 μm to 5 mm, and more preferably 500 μm to 2 mm.

  Next, the manufacturing method of the mirror 10 with the image display function for vehicles of 1st Embodiment is demonstrated, referring FIG. In FIG. 4, it is assumed that the process proceeds in the direction of the arrow.

  First, the quarter wavelength plate 23 is prepared, and the second adhesive layer 25 is formed on one surface of the quarter wavelength plate 23. Specifically, for example, the pressure-sensitive adhesive layer of the OCA sheet from which the release sheet on one side is peeled is attached to one side of the quarter-wave plate 23, and then the other side of the OCA sheet is peeled off. The sheet is peeled off, whereby the second adhesive layer 25 is formed.

  Next, the front plate 22 is affixed on the adhesive surface of the second adhesive layer 25. Next, the first adhesive layer 24 is formed on the front plate 22. Specifically, for example, the pressure-sensitive adhesive layer of the OCA sheet from which the release sheet on one side has been peeled is attached to the front plate 22, and then the release sheet on the other side of the OCA sheet is peeled off. A first adhesive layer 24 is formed.

  And the circularly polarized light reflection part 12 is formed by affixing the linearly polarized light reflecting layer 21 on the adhesive surface of the first adhesive layer 24.

  The circularly polarized light reflecting portion 12 can be formed by bonding members wound in a roll shape, whereby a large-area sheet-like circularly polarized light reflecting portion 12 can be formed. The sheet-like circularly polarized light reflecting portion 12 formed in this way is cut in accordance with the shape of a final product such as a vehicle rearview mirror.

  Then, the circularly polarized light reflecting portion 12 cut into an appropriate shape is adhered to the image display surface 20a of the image display portion 20, whereby the vehicle image display function mirror 10 of the first embodiment is formed.

  In addition, you may make it perform a hard-coat process with respect to the surface which the circularly polarized light reflection part 12 in the mirror 10 with an image display function for vehicles of the said 1st Embodiment exposed. That is, a protective function may be provided by performing a hard coat process on the surface of the circularly polarized light reflecting portion 12 opposite to the front plate 22 side of the quarter wavelength plate 23.

  There is no restriction | limiting in particular as a method of forming a hard-coat layer by a hard-coat process, A well-known method can be used.

  Examples of the method for forming the hard coat layer include vapor deposition such as coating or sputtering. Among them, coating is preferable, and a polyfunctional monomer or oligomer is included to obtain a certain hardness. It is desirable to apply a coating solution, and to harden after drying.

  The coating solution is preferably prepared by dissolving and / or dispersing a material in a solvent. For coating the coating solution, various methods such as a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method can be employed. Alternatively, the liquid crystal composition may be discharged from a nozzle using an inkjet apparatus to form a coating film.

  There is no particular limitation on the material used for forming the hard coat layer. For example, various materials conventionally used as a material for the hard coat layer such as a polymer film (for example, a PET film) can be used.

  The pencil hardness of the hard coat layer formed by the hard coat treatment is preferably 2H or more. There is no restriction | limiting in particular as a method of controlling the pencil hardness of a hard-coat layer to 2H or more, A well-known method can be used. For example, the hard coat layer composition preferably uses at least one bifunctional or higher polymerizable monomer as a main component. This is because the pencil hardness of the hard coat layer obtained after polymerization by light irradiation or heat is easily controlled to 2H or more.

  The bifunctional or higher polymerizable monomer is preferably a bifunctional or higher (meth) acrylate. Here, the bifunctional or higher functional monomer means a monomer in which two or more polymerizable groups are contained in one monomer molecule.

  The bifunctional or higher (meth) acrylate is preferably photopolymerizable. Moreover, according to the pencil hardness calculated | required, only 1 type may be used for bifunctional or more (meth) acrylate, or 2 or more types may be mixed and used for it. As such a bifunctional or higher functional (meth) acrylate, known ones can be used, and among them, use of dipentaerythritol hexaacrylate (DPHA) or pentaerythritol tetraacrylate (PETA) ensures hardness. It is preferable from the viewpoint.

  Furthermore, in addition to the bifunctional or higher functional (meth) acrylate, the hard coat layer composition further contains a monofunctional (meth) acrylate for the purpose of adjusting the viscosity at the time of coating and the pencil hardness after film formation. Also good.

  The pencil hardness is measured by a method based on JIS K5400 (pencil scratch test method).

  As shown in FIG. 5, a protective plate 27 made of glass or plastic may be provided on the circularly polarized light reflecting portion 12 in the vehicle image display function-equipped mirror 10 of the first embodiment. That is, the protective plate 27 may be provided on the surface of the circularly polarized light reflecting portion 12 opposite to the front plate 22 side of the quarter wavelength plate 23. When a plastic plate is used as the protective plate 27, polyester such as polyethylene terephthalate, polycarbonate, acrylic resin, epoxy resin, polyurethane, polyamide, polyolefin, cellulose derivative, or silicone can be used. The film thickness of the protective plate 27 may be about 100 μm to 10 mm, preferably 200 μm to 5 mm, and more preferably 500 μm to 2 mm. The protective plate 27 and the quarter-wave plate 23 are preferably bonded by a single adhesive layer 26, and may be bonded by, for example, an OCA sheet or PVB (polyvinyl butyral).

  Next, a second embodiment of the vehicle image display function mirror of the present invention will be described in detail with reference to the drawings. Similarly to the vehicle image display function mirror 10 of the first embodiment, the vehicle image display function mirror 30 of the second embodiment is also used for the vehicle room mirror 2 shown in FIG. . However, the present invention is not limited to this, and may be used for a side mirror or a mirror attached to another vehicle.

  As shown in FIG. 2, the second mirror 30 with an image display function for a vehicle receives an image display unit 20 that can display a captured image around the vehicle, and photographic image light displayed on the image display unit 20. And a circularly polarized light reflecting portion 13. The second vehicle image display function-equipped mirror 30 is different from the first vehicle image display function-equipped mirror 10 in that the configuration of the circularly polarized light reflecting portion 13 is different. The image display unit 20 is the same as that in the first embodiment.

  As shown in FIG. 2, the circularly polarized light reflection unit 13 is provided on the image display surface 20 a side of the image display unit 20, as in the circular polarization reflection unit 12 of the first embodiment.

  And the circularly polarized light reflection part 13 functions as a semi-transmissive semi-reflective layer in the mirror 30 with an image display function for a vehicle of the second embodiment, like the circularly polarized light reflection part 12 of the first embodiment. That is, when the captured image is displayed on the image display unit 20, the circularly polarized light reflection unit 13 transmits the emitted light (captured image light) from the image display unit 20, thereby providing a mirror with an image display function for vehicles. 10 so that a photographed image is displayed on the front surface.

  On the other hand, when the captured image is not displayed on the image display unit 20, the circularly polarized light reflection unit 13 receives incident light from the side opposite to the image display unit 20 side (from the arrow S direction side shown in FIG. 2). It reflects and functions so that the front surface of the mirror 30 with an image display function for vehicles becomes a mirror.

  FIG. 6 is a cross-sectional view taken along line B-C of the vehicle image display function-equipped mirror 30 shown in FIG. As shown in FIG. 6, the circularly polarized light reflecting portion 13 includes a quarter-wave plate 31, a circularly polarized light reflecting layer 32, a front plate 33 made of glass or plastic, and a high retardation plate 34. . In the present embodiment, the circularly polarized light reflecting layer 32 corresponds to a dichroic polarized light reflecting layer, and the high retardation plate 34 corresponds to an optical compensation layer.

  The quarter wavelength plate 31, the circularly polarized light reflecting layer 32, the front plate 33, and the high retardation plate 34 are arranged in this order from the image display unit 20 side. That is, the quarter-wave plate 31 and the circularly polarizing reflection layer 32 are disposed on the image display unit 20 side with respect to the front plate 33, and the high retardation plate 34 is disposed on the opposite side of the image display unit 20 with respect to the front plate 22. Has been placed.

  With such a configuration, the circularly polarized light reflecting portion 13 functions as a semi-transmissive / semi-reflective layer. However, as shown in FIG. 6, the mirror surface is formed on the surface 32 a of the circularly polarized light reflecting layer 32 on the front plate 33 side.

  The quarter-wave plate 31 and the circularly polarizing reflection layer 32 and the front plate 33 are bonded by a single first adhesive layer 35, and the front plate 33 and the high retardation plate 34 are a single layer second adhesive. Bonded by layer 36.

  Here, the adhesion by the single first adhesive layer 35 or the second adhesive layer 36 means that between the quarter wave plate 31 and the circularly polarized light reflecting layer 32 and the front plate 33 or the front plate 33. It means that only one adhesive layer is disposed between the high retardation plate 34 and no adhesive layer other than the first adhesive layer 35 or the second adhesive layer 36. The first adhesive layer 35 itself and the second adhesive layer 36 itself may be formed of a plurality of layers.

  In the vehicle image display function mirror 30 of the present embodiment, the laminated body of the quarter-wave plate 31 and the circularly polarized light reflection layer 32 and the front plate 33 are bonded by the single first adhesive layer 35, and the front Since the high phase difference plate 34 is arranged on the side opposite to the image display unit 20 side with respect to the face plate 33, a clear image and mirror reflection can be obtained without direction dependency even when the user uses polarized sunglasses or the like. The image can be visually recognized, and the distortion of the reflected image can be suppressed. Further, since the front plate 33 and the high retardation plate 34 are also bonded by the single second adhesive layer 36, distortion of the reflected image can be further suppressed. The operational effects of the high retardation plate 34 will be described in detail later.

  As the 1st adhesion layer 35 and the 2nd adhesion layer 36, an OCA sheet can be used like the 1st embodiment of the above. The thickness of the first adhesive layer 35 and the second adhesive layer 36 is preferably 10 μm or more and 25 μm or less. The reason is the same as in the first embodiment.

  It is desirable to leave a gap between the image display unit 20 and the quarter wavelength plate 31 by fixing them to a frame or the like. However, the image display unit 20 and the quarter wavelength plate 31 may be directly bonded. Further, although other layers such as an adhesive layer may be included between the quarter-wave plate 31 and the circularly-polarized reflective layer 32, the quarter-wave plate 31 and the circularly-polarized reflective layer 32 are directly connected to each other. It is preferable to contact. Moreover, it is preferable that the quarter wavelength plate 31 and the circularly polarized light reflection layer 32 are laminated with the same area.

  The quarter-wave plate 31 is preferably angle-adjusted so that the image is brightest. That is, the polarization direction (transmission axis) of the linearly polarized light and the slow axis of the quarter-wave plate 31 so that the linearly polarized light is transmitted best with respect to the image display unit 20 that displays an image with linearly polarized light. It is preferable that the relationship is adjusted. For example, in the case of a single layer type quarter wave plate 31, it is preferable that the transmission axis and the slow axis form an angle of 45 °. The light emitted from the image display unit 20 displaying an image by linearly polarized light is circularly polarized light of either right or left sense after passing through the quarter wavelength plate 31. The circularly polarized light reflecting layer 32 to be described later is preferably composed of a cholesteric liquid crystal layer having a twist direction that transmits the circularly polarized light having the above-described sense.

  In the mirror 30 with an image display function for a vehicle of the present embodiment, the light from the image display unit 20 is circularly polarized by including the quarter wavelength plate 31 between the image display unit 20 and the circularly polarized reflection layer 32. And can be made incident on the circularly polarized light reflecting layer 32. Therefore, the light reflected by the circularly polarized light reflection layer 32 and returning to the image display unit 20 side can be greatly reduced, and a bright image can be displayed.

  In this specification, “selective” for circularly polarized light means that the amount of light of either the right circularly polarized component or the left circularly polarized component of the irradiated light is greater than the other circularly polarized component. To do. Specifically, when referred to as “selective”, 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. More preferably, it is substantially 1.0. Here, the degree of circular polarization is a value represented by | IR−IL | / (IR + IL) where IR is the intensity of the right circular polarization component of light and IL is the intensity of the left circular polarization component.

  In this specification, “sense” for circularly polarized light means right circularly polarized light or left circularly polarized light. The sense of circularly polarized light is right-handed circularly polarized light when the electric field vector tip turns clockwise as time increases when viewed as the light travels toward you, and left when it turns counterclockwise. Defined as being circularly polarized.

  In this specification, the term “sense” may be used for the twist direction of the spiral of the cholesteric liquid crystal. The selective reflection by the cholesteric liquid crystal reflects right circularly polarized light when the twist direction (sense) of the cholesteric liquid crystal spiral is right, transmits left circularly polarized light, and reflects left circularly polarized light when the sense is left, Transmits circularly polarized light.

  The quarter wavelength plate 31 may be a retardation layer that functions as a quarter wavelength plate in the visible light region. Examples of the quarter-wave plate 31 include a single-layer quarter-wave plate, a broadband quarter-wave plate in which a quarter-wave plate and a half-wave retardation plate are stacked, and the like. The front phase difference of the former ¼ wavelength plate may be a length that is ¼ of the emission wavelength of the image display unit 20. Therefore, for example, when the emission wavelength of the image display unit 20 is 450 nm, 530 nm, and 640 nm, the phase difference is 112.5 nm ± 10 nm, preferably 112.5 nm ± 5 nm, more preferably 112.5 nm at the wavelength of 450 nm, A phase difference of 132.5 nm ± 10 nm, preferably 132.5 nm ± 5 nm, more preferably 132.5 nm at a wavelength of 530 nm, and 160 nm ± 10 nm, preferably 160 nm ± 5 nm, more preferably 160 nm at a wavelength of 640 nm. It is most preferable to use a reverse dispersion retardation layer that is a phase difference as a quarter-wave plate, but a retardation plate having a small retardation wavelength dispersion or a forward dispersion retardation plate can also be used. . Note that reverse dispersion means the property that the absolute value of the phase difference increases as the wavelength becomes longer, and forward dispersion means the property that the absolute value of the phase difference increases as the wavelength becomes shorter.

  The laminated quarter-wave plate is formed by laminating a quarter-wave plate and a half-wave retardation plate at an angle of 60 ° with the slow axis, and the side of the half-wave retardation plate is linearly polarized. It is arranged on the incident side, and the slow axis of the half-wave retardation plate is used so as to intersect 15 ° or 75 ° with respect to the polarization plane of the incident linearly polarized light. Can be suitably used because of its good resistance. In the present specification, the phase difference means frontal retardation. The phase difference can be measured using a polarization phase difference analyzer AxoScan manufactured by AXOME RICS. Alternatively, measurement may be performed by making light of a specific wavelength incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).

  There is no restriction | limiting in particular as the quarter wavelength plate 31, According to the objective, it can select suitably. For example, a quartz plate, a stretched polycarbonate film, a stretched norbornene polymer film, a transparent film oriented containing inorganic particles having birefringence such as strontium carbonate, and an inorganic dielectric obliquely on a support For example, a deposited thin film.

  Moreover, as the quarter wavelength plate 31, the thing quoted as an example of the quarter wavelength plate 23 of the circularly polarized light reflection part 12 of the said 1st Embodiment can also be used.

  The circularly polarized light reflection layer 32 includes at least one cholesteric liquid crystal layer exhibiting selective reflection in the visible light region. The circularly polarized light reflecting layer 32 may include two or more cholesteric liquid crystal layers, and may include other layers such as an alignment layer. The circularly polarized light reflecting layer 32 is preferably composed only of a cholesteric liquid crystal layer.

  Moreover, when the circularly polarized light reflection layer 32 includes a plurality of cholesteric liquid crystal layers, it is preferable that they are in direct contact with the adjacent cholesteric liquid crystal layers. The circularly polarized light reflection layer 32 preferably includes three or more cholesteric liquid crystal layers such as three layers and four layers. The thickness of the circularly polarized light reflecting layer 32 is preferably 2.0 μm to 300 μm, more preferably 8. It is 0-200 micrometers.

  In this specification, a cholesteric liquid crystal layer means a layer in which a cholesteric liquid crystal phase is fixed. The cholesteric liquid crystal layer is sometimes simply referred to as a liquid crystal layer. The cholesteric liquid crystal phase selectively reflects the circularly polarized light of either the right circularly polarized light or the left circularly polarized light in a specific wavelength range, and exhibits circularly polarized selective reflection that transmits the circularly polarized light of the other sense. It has been known. In this specification, the circularly polarized light selective reflection is sometimes simply referred to as selective reflection. Many films formed from a composition containing a polymerizable liquid crystal compound have been known as a film containing a layer in which a cholesteric liquid crystal phase exhibiting circularly polarized light selectively is fixed. You can refer to the technology.

  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. Typically, the polymerizable liquid crystal compound is placed in the orientation state of the cholesteric liquid crystal phase and then irradiated with ultraviolet rays. Any layer may be used as long as it is polymerized and cured by heating or the like to form a layer having no fluidity, and at the same time, the layer is changed to a state in which the orientation is not changed by an external field or external force. 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 crystalline compound in the layer may no longer exhibit liquid crystallinity. For example, the polymerizable liquid crystal compound may have a high molecular weight due to a curing reaction and may no longer have liquid crystallinity.

  The central wavelength λ of 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. In this specification, the central wavelength λ of selective reflection of the cholesteric liquid crystal layer means a wavelength at the center of gravity of the reflection peak of the circularly polarized reflection spectrum measured from the normal direction of the cholesteric liquid crystal layer. In the present specification, the center wavelength of selective reflection means the center wavelength when measured from the normal direction of the cholesteric liquid crystal layer. As can be seen from the above equation, the center wavelength of selective reflection can be adjusted by adjusting the pitch of the helical structure. The center wavelength λ can be adjusted in order to selectively reflect either the right circularly polarized light or the left circularly polarized light with respect to light of a desired wavelength by adjusting the n value and the P value.

When light is incident on the cholesteric liquid crystal layer at an angle, the center wavelength of selective reflection is shifted 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 wavelength of selective reflection required for image display. When the central wavelength of selective reflection when a light ray passes at an angle of θ ₁ with respect to the normal direction of the cholesteric liquid crystal layer (the spiral axis direction of the cholesteric liquid crystal layer) in the cholesteric liquid crystal layer having a refractive index n ₁ is λd , Λd are expressed by the following equations.
λd = n ₁ × P × cos θ ₁

  Due to the selective reflection property described above, the mirror with an image display function of the present invention may appear in a display image and a reflected image as seen from an oblique direction. By including a cholesteric liquid crystal layer having a center wavelength of selective reflection in the infrared light region in the circularly polarized light reflecting layer, it is possible to prevent this color. In this case, the center wavelength of selective reflection in the infrared region is specifically 780 to 900 nm, preferably 780 to 850 nm.

  Since the pitch of the cholesteric liquid crystal phase depends on the type of chiral agent used together with the polymerizable liquid crystal compound or the concentration of the chiral agent, the desired pitch can be obtained by adjusting these. For the method of measuring spiral sense and pitch, the method described in “Introduction to Liquid Crystal Chemistry Experiments”, Japanese Liquid Crystal Society, Sigma Publishing 2007, page 46, and “Liquid Crystal Handbook”, Liquid Crystal Handbook Editorial Board Maruzen, page 196 is used. be able to.

  The circularly polarized light reflecting layer 32 is selected for 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 wavelength range of blue light. And a cholesteric liquid crystal layer having a central wavelength of reflection. The circularly polarized light reflecting layer 32 has, for example, a cholesteric liquid crystal layer having a central wavelength of selective reflection at 400 nm to 500 nm, a cholesteric liquid crystal layer having a central wavelength of selective reflection at 500 nm to 580 nm, and a central wavelength of selective reflection at 580 nm to 700 nm. It is preferable to include a cholesteric liquid crystal layer. Further, when the circularly polarized light reflection layer includes a plurality of cholesteric liquid crystal layers, it is preferable that the cholesteric liquid crystal layer closer to the image display unit 20 has a longer selective reflection center wavelength. With such a configuration, it is possible to suppress oblique color in the display image and the reflected image.

  By adjusting the central wavelength of selective reflection of the cholesteric liquid crystal layer to be used according to the emission wavelength range of the image display unit 20 and the usage mode of the circularly polarized light reflecting layer 32, a bright image can be displayed with high light utilization efficiency. . Examples of usage of the circularly polarized light reflecting layer 32 include an incident angle of light to the circularly polarized light reflecting layer 32 and an image observation direction.

  The sense of reflected circularly polarized light in the cholesteric liquid crystal layer coincides with the sense of a spiral. Each cholesteric liquid crystal layer has either a right or left spiral sense depending on the sense of circularly polarized light sensed from the image display unit 20 and transmitted through the quarter-wave plate 31. Some cholesteric liquid crystal layer is used. Specifically, a cholesteric liquid crystal layer having a spiral sense that transmits the circularly polarized light of the sense obtained from the image display unit 20 and transmitted through the quarter-wave plate 31 may be used. When the circularly polarized light reflecting layer 32 includes a plurality of cholesteric liquid crystal layers, it is preferable that the senses of the spirals are all the same.

  The full width at half maximum Δλ (nm) of the selective reflection band showing selective reflection depends on the relationship of Δλ = Δn × P, where Δλ depends on the birefringence Δn of the liquid crystal compound and the pitch P. Therefore, the width of the selective reflection band can be controlled by adjusting Δn. Δn can be adjusted by adjusting the kind of the polymerizable liquid crystal compound and the mixing ratio thereof, or by controlling the temperature at the time of fixing the alignment. In order to form one type of cholesteric liquid crystal layer having the same central wavelength of selective reflection, a plurality of cholesteric liquid crystal layers having the same period P and the same spiral sense may be stacked. By laminating cholesteric liquid crystal layers having the same period P and the same spiral sense, the circularly polarized light selectivity can be increased at a specific wavelength.

  Next, a production material and a production method of the quarter wavelength plate 31 and the cholesteric liquid crystal layer will be described. Examples of the material used for forming the quarter-wave plate 31 include a liquid crystal composition containing a polymerizable liquid crystal compound. The material used for forming the cholesteric liquid crystal layer preferably further contains a chiral agent (an optically active compound). A cholesteric liquid crystal layer as a support, a temporary support, an alignment film, a quarter-wave plate, or a lower layer, which is mixed with a surfactant or a polymerization initiator as necessary and dissolved in a solvent. After ripening the alignment, it can be fixed by curing the liquid crystal composition to form a cholesteric liquid crystal layer. In addition, the cholesteric liquid crystal layer can be formed by applying to a support, a temporary support, an alignment film, or a lower cholesteric liquid crystal layer, and fixing the liquid crystal composition after the alignment aging.

  A rod-like liquid crystal compound may be used as the polymerizable liquid crystal compound. Examples of the rod-like polymerizable liquid crystal compound include a rod-like nematic liquid crystal compound. Examples of rod-like nematic liquid crystal compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Not only low-molecular liquid crystal compounds but also high-molecular liquid crystal compounds can be used.

  The polymerizable liquid crystal compound can be obtained by introducing a polymerizable group into the liquid crystal compound. Examples of the polymerizable group include an unsaturated polymerizable group, an epoxy group, and an aziridinyl group, preferably an unsaturated polymerizable group, and particularly preferably an ethylenically unsaturated polymerizable group. The polymerizable group can be introduced into the molecule of the liquid crystal compound by various methods. The number of polymerizable groups possessed by the polymerizable liquid crystal compound is preferably 1 to 6, more preferably 1 to 3. Examples of polymerizable liquid crystal compounds are described in Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. Nos. 4,683,327, 5,622,648 and 5,770,107, International Publication No. 1995/22586. Pamphlet, International Publication No. 1995/24455, International Publication No. 1997/00600, International Publication No. 1998/23580, International Publication No. 1998/52905, JP-A-1-272551, 6-16616. And the compounds described in JP-A-7-110469, JP-A-11-80081, JP-A-2001-328773, and the like. Two or more kinds of polymerizable liquid crystal compounds may be used in combination. When two or more kinds of polymerizable liquid crystal compounds are used in combination, the alignment temperature can be lowered.

  Moreover, it is preferable that the addition amount of the polymeric liquid crystal compound in a liquid-crystal composition is 80-99.9 mass% with respect to solid content mass (mass except a solvent) of a liquid-crystal composition, and 85-99. More preferably, it is 5 mass%, and it is especially preferable that it is 90-99 mass%.

  The material used for forming the cholesteric liquid crystal layer preferably contains a chiral agent. The chiral agent has a function of inducing a helical structure of a cholesteric liquid crystal phase. The chiral compound may be selected according to the purpose because the helical sense or helical pitch induced by the compound is different. There is no restriction | limiting in particular as a chiral agent, For example, a well-known compound (For example, liquid crystal device handbook, Chapter 3, 4-3, TN, a chiral agent for STN, 199 pages, Japan Society for the Promotion of Science 142th Committee edition, 1989. ), Isosorbide and isomannide derivatives can be used. A chiral agent generally contains an asymmetric carbon atom, but an axially asymmetric compound or a planar asymmetric compound containing no asymmetric carbon atom can also be used as the chiral agent. Examples of the axial asymmetric compound or the planar 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, they are derived from the repeating unit derived from the polymerizable liquid crystal compound and the chiral agent by a polymerization reaction between the polymerizable chiral agent and the polymerizable liquid crystal compound. A polymer having repeating units can be formed. In this aspect, the polymerizable group possessed by the polymerizable chiral agent is preferably the same group as the polymerizable group possessed by 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 an ethylenically unsaturated polymerizable group. Particularly preferred. The chiral agent may be a liquid crystal compound.

  It is preferable that the chiral agent has a photoisomerizable group because a pattern having a desired reflection wavelength corresponding to the emission wavelength can be formed by irradiation with a photomask such as actinic rays after coating and orientation. As a photoisomerization group, the isomerization part of the compound which shows photochromic property, an azo, an azoxy, and a cinnamoyl group are preferable. Specific examples of the compound include JP 2002-80478, JP 2002-80851, JP 2002-179668, JP 2002-179669, JP 2002-179670, and JP 2002-2002. The compounds described in JP-A No. 179681, JP-A No. 2002-179682, JP-A No. 2002-338575, JP-A No. 2002-338668, JP-A No. 2003-313189, and JP-A No. 2003-313292 are used. be able to. The content of the chiral agent in the liquid crystal composition is preferably from 0.01 mol% to 200 mol%, more preferably from 1 mol% to 30 mol%, based on the amount of the polymerizable liquid crystal compound.

  The liquid crystal composition preferably contains a polymerization initiator. In the embodiment in which the polymerization reaction is advanced by ultraviolet irradiation, the polymerization initiator to be used is preferably a photopolymerization initiator that can start the polymerization reaction by ultraviolet irradiation. Examples of photopolymerization initiators include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatics. An acyloin compound (described in U.S. Pat. No. 2,722,512), a polynuclear quinone compound (described in U.S. Pat. Nos. 304-6127 and 2951758), a combination of triarylimidazole dimer and p-aminophenyl ketone ( U.S. Pat. No. 3,549,367), acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850), oxadiazole compounds (U.S. Pat. No. 4,129,970), etc. Is mentioned. The content of the photopolymerization initiator in the liquid crystal composition is preferably 0.1 to 20% by mass, and preferably 0.5 to 5% by mass with respect to the content of the polymerizable liquid crystal compound. Even more preferred.

  The liquid crystal composition may optionally contain a crosslinking agent in order to improve the film strength after curing and improve the durability. As the crosslinking agent, those that are cured by ultraviolet rays, heat, moisture, or the like can be suitably used. There is no restriction | limiting in particular as a crosslinking agent, According to the objective, it can select suitably, For example, polyfunctional acrylate compounds, such as a trimethylol propane tri (meth) acrylate and pentaerythritol tri (meth) acrylate; Glycidyl (meth) acrylate , Epoxy compounds such as ethylene glycol diglycidyl ether; aziridine compounds such as 2,2-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], 4,4-bis (ethyleneiminocarbonylamino) diphenylmethane; hexa Isocyanate compounds such as methylene diisocyanate and biuret type isocyanate; polyoxazoline compounds having an oxazoline group in the side chain; vinyltrimethoxysilane, and N- (2-aminoethyl) 3-aminopro Alkoxysilane compounds such as Le trimethoxysilane. Moreover, a well-known catalyst can be used according to the reactivity of a crosslinking agent, and productivity can be improved in addition to membrane strength and durability improvement. These may be used individually by 1 type and may use 2 or more types together. 3 mass%-20 mass% are preferable, and, as for content of a crosslinking agent, 5 mass%-15 mass% are more preferable. When the content of the crosslinking agent is less than 3% by mass, the effect of improving the crosslinking density may not be obtained. When the content exceeds 20% by mass, the stability of the formed layer may be lowered. .

  An alignment control agent that contributes to stable or rapid planar alignment may be added to the liquid crystal composition. Examples of the orientation control agent include fluorine (meth) acrylate polymers described in paragraphs [0018] to [0043] of JP-A-2007-272185, and paragraphs [0031] to [0031] of JP-A No. 012-203237. And compounds represented by the formulas (I) to (IV) described in the above. In addition, as an orientation control agent, 1 type may be used independently and 2 or more types may be used together.

  The addition amount of the alignment control agent in the liquid crystal composition is preferably 0.01% by mass to 10% by mass, more preferably 0.01% by mass to 5% by mass with respect to the total mass of the polymerizable liquid crystal compound. 0.02% by mass to 1% by mass is particularly preferable.

  The liquid crystal composition may further 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. Good. Further, in the liquid crystal composition, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, a coloring material, metal oxide fine particles, and the like are added in a range that does not deteriorate the optical performance, if necessary. Can be added.

  There is no restriction | limiting in particular as a solvent used for preparation of a liquid-crystal composition, Although it can select suitably according to the objective, An organic solvent is used preferably. The organic solvent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include ketones, alkyl halides, amides, sulfoxides, heterocyclic compounds, hydrocarbons, esters, and ethers. Is mentioned. These may be used alone or in combination of two or more. Among these, ketones are particularly preferable in consideration of environmental load.

  The method of applying the liquid crystal composition to the temporary support, the alignment film, the quarter wavelength plate, or the cholesteric liquid crystal layer as the lower layer is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a bar coating method, a curtain coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a die coating method, a spin coating method, a dip coating method, a spray coating method, and a slide coating method. It can also be carried out by transferring a liquid crystal composition separately coated on a support. The liquid crystal molecules are aligned by heating the applied liquid crystal composition. In forming the cholesteric liquid crystal layer, cholesteric alignment may be performed, and in forming the quarter-wave plate, nematic alignment is preferable. In the cholesteric orientation, the heating temperature is preferably 200 ° C. or lower, and more preferably 130 ° C. or lower. By this alignment treatment, an optical thin film in which the polymerizable liquid crystal compound is twisted and aligned so as to have a helical axis in a direction substantially perpendicular to the film surface is obtained. In the case of nematic orientation, the heating temperature is preferably 50 ° C to 120 ° C, more preferably 60 ° C to 100 ° C.

The aligned liquid crystal compound can be further polymerized to cure the liquid crystal composition. The polymerization may be either thermal polymerization or photopolymerization by light irradiation, but photopolymerization is preferred. It is preferable to use ultraviolet rays for light irradiation. The irradiation energy ^{is, 20mJ / cm 2 ~50J / cm} 2 is favorable ^{Mashiku, 100mJ / cm 2 ~1,500mJ / cm} 2 is more preferable. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions or in a nitrogen atmosphere. The irradiation ultraviolet wavelength is preferably 350 nm to 430 nm. The polymerization reaction rate is preferably as high as possible from the viewpoint of stability, preferably 70% or more, and more preferably 80% or more. The polymerization reaction rate can determine the consumption rate of a polymerizable functional group using an IR absorption spectrum.

  The thickness of each cholesteric liquid crystal layer is not particularly limited as long as it exhibits the above characteristics, but is preferably in the range of 1.0 to 150 μm, more preferably in the range of 4.0 to 100 μm. Although the thickness of the quarter wavelength plate formed from a liquid crystal composition is not specifically limited, Preferably it is 0.2-10 micrometers, More preferably, it is 0.5-2 micrometers.

  The liquid crystal composition may be applied and layered on the surface of the temporary support or the alignment layer formed on the surface of the temporary support. The temporary support or the temporary support and the alignment layer may be peeled off after forming the layer. Further, a support may be used particularly when forming a quarter wavelength plate. The support does not have to be peeled off after forming the layer. 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 alignment layer is formed by rubbing treatment of organic compounds such as polymers (resins such as polyimide, polyvinyl alcohol, polyester, polyarylate, polyamideimide, polyetherimide, polyamide, and modified polyamide), oblique deposition of inorganic compounds, and microgrooves. Or by accumulating organic compounds (for example, ω-tricosanoic acid, dioctadecylmethylammonium chloride, methyl stearylate) by the Langmuir-Blodgett method (LB film). . Further, an alignment layer that generates an alignment function by application of an electric field, application of a magnetic field, or light irradiation may be used. In particular, the alignment layer made of a polymer is preferably subjected to a rubbing treatment and then a liquid crystal composition is applied to the rubbing treatment surface. The rubbing treatment can be performed by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth. The liquid crystal composition may be applied to the surface of the temporary support without providing the alignment layer, or the surface obtained by rubbing the temporary support. The thickness of the alignment layer is preferably 0.01 to 5 μm, and more preferably 0.05 to 2 μm.

  As described above, the quarter-wave plate 31 and the cholesteric liquid crystal layer are composed of a liquid crystal composition in which a polymerizable liquid crystal compound and a polymerization initiator, a chiral agent added as necessary, a surfactant, and the like are dissolved in a solvent. The product is applied onto a temporary support, an alignment layer, a quarter-wave plate, or a cholesteric liquid crystal layer previously prepared, and dried to obtain a coating film. It can be formed by orienting the compound and then polymerizing the polymerizable compound to fix the orientation. A laminate of layers formed from a polymerizable liquid crystal compound can be formed by repeating the above steps. Alternatively, a part of the layers or a part of the stacked films may be separately manufactured and bonded together with an adhesive layer.

  When forming a laminated film of a quarter-wave plate 31 and a cholesteric liquid crystal layer, a laminated film made up of a plurality of cholesteric liquid crystal layers, or a laminated film made up of a quarter-wave plate 31 and a plurality of cholesteric liquid crystal layers, The liquid crystal composition containing a polymerizable liquid crystal compound or the like may be directly applied to the surface of the / 4 wavelength plate 31 or the previous cholesteric liquid crystal layer, and the alignment and fixing steps may be repeated. In the laminated film of the cholesteric liquid crystal layer, the liquid crystal on the air interface side of the cholesteric liquid crystal layer formed earlier is formed by forming the next cholesteric liquid crystal layer so as to be in direct contact with the surface of the cholesteric liquid crystal layer formed earlier. The alignment orientation of the molecules coincides with the orientation orientation of the liquid crystal molecules below the cholesteric liquid crystal layer formed thereon, and the polarization property of the laminate of the cholesteric liquid crystal layer is improved.

  The high phase difference plate 34 means a plate having a front phase difference of 5000 nm or more. The front retardation of the high retardation plate 34 is preferably 6000 nm or more, and more preferably 8000 nm or more. The front retardation of the high retardation plate 34 is preferably as large as possible, but may be 100000 nm or less, 50000 nm or less, 40000 nm or less, or 30000 nm or less in consideration of manufacturing efficiency and thinning.

  The high phase difference plate 34 and the quarter wavelength plate having a high front phase difference as described above may cause the polarized light generated when sunlight passes through the vehicle window glass (particularly the rear glass) to be pseudo-non-polarized. it can. About the front phase difference which can make polarized light pseudo-non-polarized, there exists description in Paragraph [0022]-[0033] of Unexamined-Japanese-Patent No. 2005-321544. The specific numerical value of the front phase difference can be determined according to the vehicle using the vehicle image display function-equipped mirror 30 of the present embodiment. In particular, it may be determined according to the magnitude of the front phase difference generated in the sunlight transmitted through the rear glass of the vehicle.

  It is known that tempered glass (for example, tempered glass which is not a laminated glass) used for vehicle window glass, particularly rear glass, has a birefringence distribution. The tempered glass is generally produced by heating a float plate glass to 700 ° C. near the softening point, and then rapidly cooling the glass surface by blowing air. This treatment lowers the temperature of the glass surface first and shrinks and solidifies, while the glass interior is slower to cool down than the surface and delays shrinking, resulting in stress distribution inside and no birefringence. Even when float glass is used, birefringence distribution occurs in the tempered glass.

  Therefore, it is considered that the light incident on the front surface of the mirror with an image display function for vehicles that passes through the rear glass of the vehicle in which the tempered glass produced as described above is used particularly causes the above-described unevenness in the reflected image. . That is, when a polarization component with a distribution is generated in the light incident on the front surface of the mirror with an image display function for a vehicle due to the birefringence distribution, the reflected light on the front surface of the mirror with the image display function for a vehicle and the selection in the circularly polarized light reflection layer 32 are selected. It is considered that a difference in the intensity of the reflected light occurs due to the interference with the reflected light, causing the unevenness of the reflected image. In the mirror 30 with a vehicle image display function of the present embodiment, the light incident on the front surface of the mirror 30 with a vehicle image display function is reflected by circularly polarized light by using the high retardation plate 34 having a predetermined phase difference. It is presumed that unevenness can be reduced by making the light non-polarized before entering the layer 32 in a pseudo manner.

  As the high retardation plate 34, a birefringent material such as a plastic film and a quartz plate can be used. Examples of the plastic include polyester films such as polyethylene terephthalate (PET), polycarbonate films, polyacetal films, and polyarylate films. JP, 2013-257579, A JP, 2015-102636, A, etc. can be referred to for a phase contrast layer which has PET as a main ingredient and has high phase contrast. As the high retardation plate 34, a commercially available product such as an optical Cosmo Shine (registered trademark) super birefringence type (manufactured by Toyobo Co., Ltd.) may be used.

  A plastic film having a high phase difference is generally formed by forming a film by melting and extruding a resin, casting it on a drum, etc., and stretching it uniaxially or biaxially 2 to 5 times while heating it. It can be formed by stretching at a magnification. Further, for the purpose of promoting crystallization and increasing the strength of the film, a heat treatment called “heat setting” may be performed at a temperature exceeding the stretching temperature after stretching.

  Further, instead of the high retardation plate 34, a quarter wavelength plate may be provided. Similarly to the high phase difference plate 34, the quarter wavelength plate can also eliminate the polarization generated when sunlight passes through the window glass of the vehicle.

  The quarter-wave plate has a function of substantially shifting the phase of reflected light by ± λ / 4. Specifically, the front phase difference at a wavelength of 550 nm may be 138 nm ± 10 nm, preferably 138 nm ± 5 nm.

  By using a ¼ wavelength plate having a predetermined phase difference in this way, the phase of incident light with different polarization states can be shifted to a region where the difference in intensity of reflected light is unlikely to occur. It is estimated that the unevenness of the reflected image can be reduced.

  In addition, also about the 1/4 phase difference plate used instead of the high phase difference plate 34, the same thing as the 1/4 wavelength plate 23 and the quarter wavelength plate 31 mentioned above can be used.

  Note that the high retardation plate described above may be provided in the vehicle image display function mirror 10 of the first embodiment. Specifically, as shown in FIG. 7, the high retardation plate 28 has an image display unit 20 with respect to the front plate 22 of the circularly polarized light reflection unit 12 in the mirror 10 with an image display function for a vehicle of the first embodiment. It may be provided on the side opposite to the side. The stacking order of the quarter wavelength plate 23 and the high retardation plate 28 may be the order of the high retardation plate 28 and the quarter wavelength plate 23 from the image display unit 20 side, or conversely from the image display unit 20 side. Although the order of the quarter wavelength plate 23 and the high retardation plate 28 may be in this order, considering that the polarization conversion accuracy by the quarter wavelength plate 23 is high and is not easily affected by the phase difference deviation by the high retardation plate 28, As shown in FIG. 7, the high retardation plate 28 and the quarter wavelength plate 23 are preferably arranged in this order from the image display unit 20 side. In this case as well, the front plate 22 and the high retardation plate 28 are preferably bonded by a single adhesive layer such as an OCA sheet.

  Moreover, you may make it provide the high phase difference plate mentioned above instead of the quarter wavelength plate 23 in the mirror 10 with a vehicle image display function of 1st Embodiment. As a result, the polarized light that has passed through the linearly polarized reflection layer 21 is eliminated, and a clear image and mirror reflection image without direction dependency can be obtained even when the user is using polarized sunglasses as in the case of the quarter-wave plate 23. The effect which can visually recognize can be acquired.

  Next, the manufacturing method of the mirror 30 with the image display function for vehicles of 2nd Embodiment is demonstrated, referring FIG. In FIG. 8, it is assumed that the process proceeds in the direction of the arrow.

  First, a high retardation plate 34 is prepared, and a second adhesive layer 36 is formed on one surface of the high retardation plate 34. Specifically, for example, the pressure-sensitive adhesive layer of the OCA sheet from which the release sheet on one side is peeled is attached to one side of the high retardation plate 34, and then the release sheet on the other side of the OCA sheet is It peels and the 2nd adhesion layer 36 is formed by this.

  Next, the front plate 33 is attached on the adhesive surface of the second adhesive layer 36. Next, the first adhesive layer 35 is formed on the front plate 33. Specifically, for example, the pressure-sensitive adhesive layer of the OCA sheet from which the release sheet on one side is peeled is attached to the front plate 33, and then the release sheet on the other side of the OCA sheet is peeled off. A first adhesive layer 35 is formed.

  Then, the circularly polarized light reflecting portion 13 is formed by adhering the laminated body of the circularly polarized light reflecting layer 32 and the quarter wavelength plate 31 on the adhesive surface of the first adhesive layer 35.

  The circularly polarized light reflecting portion 13 can be formed by bonding members wound in a roll shape, whereby a large-area sheet-like circularly polarized light reflecting portion 13 can be formed. The sheet-like circularly polarized light reflecting portion 13 formed in this way is cut in accordance with the shape of the final product such as a vehicle rearview mirror.

  Then, the circularly polarized light reflecting portion 13 cut into an appropriate shape is adhered to the image display surface 20a of the image display portion 20, whereby the vehicle image display function mirror 10 of the first embodiment is formed.

  In addition, you may make it perform a hard-coat process with respect to the surface which the circularly polarized light reflection part 13 in the mirror 30 with a vehicle image display function of the said 2nd Embodiment exposed. That is, a protective function may be provided by performing a hard coat process on the surface of the circularly polarized light reflecting portion 13 opposite to the front plate 33 side of the high retardation plate 34.

  There is no restriction | limiting in particular as a method of forming a hard-coat layer by a hard-coat process, A well-known method can be used.

  Examples of the method for forming the hard coat layer include vapor deposition such as coating or sputtering. Among them, coating is preferable, and a polyfunctional monomer or oligomer is included to obtain a certain hardness. It is desirable to apply a coating solution, and to harden after drying.

  The coating solution is preferably prepared by dissolving and / or dispersing a material in a solvent. For coating the coating solution, various methods such as a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method can be employed. Alternatively, the liquid crystal composition may be discharged from a nozzle using an inkjet apparatus to form a coating film.

  There is no particular limitation on the material used for forming the hard coat layer. For example, various materials conventionally used as a material for the hard coat layer such as a polymer film (for example, a PET film) can be used.

  The pencil hardness of the hard coat layer formed by the hard coat treatment is preferably 2H or more. There is no restriction | limiting in particular as a method of controlling the pencil hardness of a hard-coat layer to 2H or more, A well-known method can be used. For example, the hard coat layer composition preferably uses at least one bifunctional or higher polymerizable monomer as a main component. This is because the pencil hardness of the hard coat layer obtained after polymerization by light irradiation or heat is easily controlled to 2H or more.

  The bifunctional or higher polymerizable monomer is preferably a bifunctional or higher (meth) acrylate. Here, the bifunctional or higher functional monomer means a monomer in which two or more polymerizable groups are contained in one monomer molecule.

  The bifunctional or higher (meth) acrylate is preferably photopolymerizable. Moreover, according to the pencil hardness calculated | required, only 1 type may be used for bifunctional or more (meth) acrylate, or 2 or more types may be mixed and used for it. As such a bifunctional or higher functional (meth) acrylate, known ones can be used, and among them, use of dipentaerythritol hexaacrylate (DPHA) or pentaerythritol tetraacrylate (PETA) ensures hardness. It is preferable from the viewpoint.

  Furthermore, in addition to the bifunctional or higher functional (meth) acrylate, the hard coat layer composition further contains a monofunctional (meth) acrylate for the purpose of adjusting the viscosity at the time of coating and the pencil hardness after film formation. Also good.

  The pencil hardness is measured by a method based on JIS K5400 (pencil scratch test method).

  Further, as shown in FIG. 9, a protective plate 38 made of glass or plastic may be provided for the circularly polarized light reflecting portion 13 in the vehicle image display function-equipped mirror 30 of the second embodiment. That is, the protective plate 38 may be provided on the surface of the circularly polarized light reflecting portion 13 opposite to the front plate 33 side of the high retardation plate 34. When a plastic plate is used as the protective plate 38, polyester such as polyethylene terephthalate, polycarbonate, acrylic resin, epoxy resin, polyurethane, polyamide, polyolefin, cellulose derivative, or silicone can be used. The thickness of the protective plate 38 may be about 100 μm to 10 mm, preferably 200 μm to 2 mm, and more preferably 500 μm to 2 mm. The protective plate 38 and the high retardation plate 34 are preferably bonded by a single-layer adhesive layer 37, and may be bonded by, for example, an OCA sheet or PVB (polyvinyl butyral).

  Examples of the present invention will be described below with reference to Tables 1 to 3.

  In the description of Tables 1 and 3 to 4, the orange peel state refers to the front side (the side opposite to the image display unit side, arrow S shown in FIG. 2) after the formation of the vehicle image display function mirror. Is the result of evaluating the state of the orange peel when viewed from the direction), A is the state where the orange peel is most inconspicuous, then the size of the orange peel gradually increases in the order of B, C and D , D is the most noticeable orange peel. Here, it is assumed that the states A to C are within the allowable range. The evaluation of the state of the orange peel was performed by a sensory test.

  Moreover, in description of Table 1 and Tables 3-4, the ease of handling is the result of evaluating the ease of handling when OCA sheets are used as the first adhesive layer and the second adhesive layer. It is the result of evaluating the amount of the adhesive remaining on the release sheet as ease of handling when the release sheet is peeled off. It is assumed that A has the smallest remaining amount, and then the remaining amount increases in the order of B and C. Here, it is assumed that A to C are within the allowable range. Evaluation of the residual amount of the adhesive was performed by a sensory test.

  In addition, the thickness of a 1st adhesion layer and a 2nd adhesion layer is measured by the Keyence Corporation multilayer film thickness measuring device SI-T series.

Example 1
Example 1 is one example of the vehicle image display function-equipped mirror 10 of the first embodiment, and has a laminated structure as shown in FIG. That is, the linearly polarized light reflection layer 21 is formed on the image display unit 20 side with respect to the front plate 22 and the quarter wavelength plate 23 is formed on the opposite side to the image display unit 20 side. As the linearly polarized light reflection layer 21, a layer prepared by adjusting the thickness of each layer so that the polarization control wavelength region is 580 nm to 720 nm based on the method described in JP-A-9-506837 was used. . As the quarter-wave plate, a pure ace manufactured by Teijin Limited was used, and a glass plate having a thickness of 1.8 mm was used as the front plate. As the first adhesive layer 24, an OCA sheet having a thickness of 15 μm (81 series (manufactured by 3M Japan)) is used, and as the second adhesive layer 25, an OCA sheet having a thickness of 50 μm (81 series (3M Japan) is used. ))). Further, as the image display unit 20, a 10-inch IPS type display device (emission peak wavelengths are 450 nm (B (Blue)), 540 nm (G (Green)), and 630 nm (R (Red))) was used.

  The state of the orange peel of the mirror with an image display function for a vehicle manufactured in Example 1 was A, and the ease of handling was also A.

(Example 2)
In Example 2, a mirror with an image display function for a vehicle was produced in the same manner as in Example 1 except that an OCA sheet having a thickness of 10 μm was used as the first adhesive layer 24 and the second adhesive layer 25. .

  The state of the orange peel of the vehicle image display function-equipped mirror produced in Example 2 was A, and the ease of handling was B.

(Example 3)
In Example 3, a mirror with an image display function for a vehicle was produced in the same manner as in Example 1 except that an OCA sheet having a thickness of 5 μm was used as the first adhesive layer 24 and the second adhesive layer 25. .

  The state of the orange peel of the vehicle image display function-equipped mirror produced in Example 3 was A, but the ease of handling was C.

Example 4
In Example 4, a mirror with an image display function for a vehicle was manufactured in the same manner as in Example 1 except that 25 μm thick OCA sheets were used as the first adhesive layer 24 and the second adhesive layer 25. .

  The state of the orange peel of the vehicle image display function-equipped mirror manufactured in Example 4 was B, and the ease of handling was A.

(Example 5)
In Example 5, a mirror with an image display function for a vehicle was produced in the same manner as in Example 1 except that 50 μm-thick OCA sheets were used as the first adhesive layer 24 and the second adhesive layer 25. .

  The orange peel state of the mirror with an image display function for a vehicle manufactured in Example 5 was C, and the ease of handling was A.

(Example 6)
In Example 6, a mirror with an image display function for a vehicle was produced in the same manner as in Example 1 except that 100 μm thick OCA sheets were used as the first adhesive layer 24 and the second adhesive layer 25. .

  The state of the orange peel of the vehicle image display function-equipped mirror manufactured in Example 6 was C, and the ease of handling was A.

(Example 7)
As shown in FIG. 5, Example 7 is the same as Example 1 except that the protective plate 27 is attached to the quarter wavelength plate 23 using an OCA sheet. A mirror with function was produced. As the protection plate 27, a glass plate having a thickness of 0.75 mm was used.

The state of the orange peel of the vehicle image display function-equipped mirror produced in Example 7 was A, and the ease of handling was A.

(Example 8)
Example 8 is an example of the vehicle image display function-equipped mirror 30 of the second embodiment, and has a stacked configuration as shown in FIG. That is, a laminated body of the quarter wavelength plate 31 and the circularly polarized light reflection layer 32 is formed on the image display unit 20 side with respect to the front plate 33, and the high retardation plate 34 is formed on the opposite side to the image display unit 20 side. The configuration.

Hereinafter, the formation method of the laminated body of the quarter wavelength plate and circularly polarized light reflection layer used in Example 8 is demonstrated.
<Preparation of liquid crystalline mixture (X)>
The following compound 1, compound 2, fluorine-based horizontal alignment agents 1 and 2, polymerization initiator, and solvent methyl ethyl ketone were mixed to prepare a coating solution having the following composition.
Compound 1 80 parts by mass Compound 2 20 parts by mass Fluorine-based horizontal alignment agent 1 0.1 part by mass Fluorine-based horizontal alignment agent 2 0.007 parts by mass Polymerization initiator IRGACURE819 (manufactured by BASF) 3 parts by mass Solvent (methyl ethyl ketone) Amount that the solute concentration is 30% by mass
<Preparation of cholesteric liquid crystalline mixture (R)>

The compound 1, the fluorine-based horizontal alignment agents 1 and 2, the chiral agent, the polymerization initiator, and the solvent methyl ethyl ketone were mixed to prepare a coating solution having the following composition.
-Compound 1 80 parts by mass-Compound 2 20 parts by mass-Fluorine-based horizontal alignment agent 1 0.1 part by mass-Fluorine-based horizontal alignment agent 2 0.007 parts by mass-Right-turning chiral agent LC756 (manufactured by BASF)
Adjustment / polymerization initiator IRGACURE819 (manufactured by BASF) 3 parts by mass / solvent (methyl ethyl ketone) in accordance with the target reflection wavelength

Coating liquids (R1), (R4) and (R7) were prepared by adjusting the formulation amount of the chiral agent LC-756 in the mixture (R). Using each coating solution, a single layer of cholesteric liquid crystal layer was prepared on the temporary support in the same manner as in the preparation of the following circularly polarized reflective layer, and the reflection characteristics were confirmed. It was a circularly polarized light reflection layer, and the center reflection wavelength was as shown in Table 2 below.
<Formation of Laminated Body of 1/4 Wave Plate and Circular Polarized Reflective Layer>

Using the coating solution prepared as described above, a laminate of a quarter-wave plate and a circularly polarizing reflection layer was prepared according to the following procedure. As a temporary support, a PET film manufactured by Fuji Film Co., Ltd. (no undercoat layer, thickness: 75 μm) was rubbed and used.
(1) The liquid crystalline mixture (X) was applied to the rubbing treated surface of the temporary support at room temperature using a wire bar so that the thickness of the dried film was 2.0 μm. After drying at room temperature for 30 seconds to remove the solvent, the mixture was heated in an atmosphere of 125 ° C. for 2 minutes, and then nematic liquid crystal phase was obtained at 85 ° C. Next, UV irradiation was performed at an output of 60% for 6 to 12 seconds with an electrodeless lamp “D bulb” (90 mW / cm 2) manufactured by Fusion UV Systems Co., Ltd., and a nematic liquid crystal phase was fixed to obtain a quarter wavelength plate. It was.
(2) Using the wire bar, the coating solution (R1) of the first layer shown in Table 2 is applied to the quarter-wave plate surface at room temperature so that the thickness of the dried film becomes 4.0 μm. Applied.
(3) After drying at room temperature for 30 seconds to remove the solvent, the mixture was heated in an atmosphere at 125 ° C. for 2 minutes, and then made a cholesteric liquid crystal phase at 95 ° C. Next, the cholesteric liquid crystal layer was prepared by fixing the cholesteric liquid crystal phase by irradiating with UV light at 60% output for 6 to 12 seconds with an electrodeless lamp “D bulb” (90 mW / cm 2) manufactured by Fusion UV Systems Co., Ltd. And cooled to room temperature.
(4) The second layer coating liquid (4) shown in Table 2 was applied to the surface of the obtained cholesteric liquid crystal layer, and the above steps (2) and (3) were repeated. Further, the third-layer coating liquid (R7) shown in Table 2 was applied to the surface of the obtained second-layer cholesteric liquid crystal, and the above steps (2) and (3) were repeated to form a quarter-wave plate. A circularly polarized light reflecting layer having three cholesteric liquid crystal layers was formed.

  As the high retardation plate 34, an optical Cosmo Shine (registered trademark) super birefringence type (manufactured by Toyobo Co., Ltd.) was used, and as the front plate 33, a glass plate having a thickness of 1.8 mm was used. As the first adhesive layer 35, an OCA sheet having a thickness of 15 μm (81 series (manufactured by 3M Japan)) is used, and as the second adhesive layer 36, an OCA sheet having a thickness of 50 μm (81 series (3M Japan) is used. ))). Further, as the image display unit 20, a 10-inch IPS type display device (emission peak wavelengths are 450 nm (B (Blue)), 540 nm (G (Green)), and 630 nm (R (Red))) was used.

  The state of the orange peel of the mirror with a vehicle image display function produced in Example 8 was A, and the ease of handling was also A.

Example 9
In Example 9, a mirror with an image display function for a vehicle was produced in the same manner as in Example 8 except that 10 μm thick OCA sheets were used as the first adhesive layer 35 and the second adhesive layer 36. .

  The orange peel state of the vehicle image display function-equipped mirror produced in Example 9 was A, and the ease of handling was B.

(Example 10)
In Example 10, a mirror with an image display function for a vehicle was produced in the same manner as in Example 8 except that an OCA sheet having a thickness of 5 μm was used as the first adhesive layer 35 and the second adhesive layer 36. .

  The orange peel state of the mirror with an image display function for a vehicle manufactured according to Example 10 was A, but the ease of handling was C.

(Example 11)
In Example 11, a mirror with an image display function for a vehicle was produced in the same manner as in Example 8 except that an OCA sheet having a thickness of 25 μm was used as the first adhesive layer 35 and the second adhesive layer 36. .

  The state of the orange peel of the vehicle image display function-equipped mirror produced in Example 11 was B, and the ease of handling was A.

(Example 12)
In Example 12, a mirror with an image display function for a vehicle was produced in the same manner as in Example 1 except that 50 μm-thick OCA sheets were used as the first adhesive layer 35 and the second adhesive layer 36. .

  The orange peel state of the vehicle image display function-equipped mirror produced in Example 12 was C, and the ease of handling was A.

(Example 13)
In Example 13, a mirror with an image display function for a vehicle was produced in the same manner as in Example 8 except that an OCA sheet having a thickness of 100 μm was used as the first adhesive layer 35 and the second adhesive layer 36. .

  The orange peel state of the mirror with an image display function for a vehicle produced in Example 13 was C, and the ease of handling was A.

(Example 14)
As shown in FIG. 9, Example 14 has a vehicle image display function in the same manner as Example 8 except that a protective plate 38 is attached to the high retardation plate 34 using an OCA sheet. A mirror was produced. As the protective plate 38, a glass plate having a thickness of 0.75 mm was used.

The state of the orange peel of the vehicle image display function-equipped mirror produced in Example 14 was A, and the ease of handling was A.

(Comparative Example 1)
In Comparative Example 1, a mirror 100 with an image display function for a vehicle was manufactured as a laminated structure as shown in FIG. That is, the ¼ wavelength plate 104 and the linearly polarized light reflection layer 103 were formed in this order from the front plate 105 toward the image display unit 101 side, and the mirror 100 with an image display function for vehicles was manufactured. The linearly polarized light reflecting layer 103, the quarter wavelength plate 104, the front plate 105, and the image display unit 101 are the same as those in the first embodiment, and the linearly polarized light reflecting layer 103 and the quarter wavelength plates 104 and 1/4 are used. Wave plate 104 and front plate 105 were bonded using OCA sheets (81 series (3M Japan)) 106 and 107, respectively. The thicknesses of the OCA sheets 106 and 107 were both 25 μm.

  The state of the orange peel of the mirror with a vehicle image display function manufactured according to Comparative Example 1 was D, and the ease of handling was A.

(Comparative Example 2)
In Comparative Example 2, a high phase difference plate, a circularly polarized light reflection layer, and a ¼ wavelength plate were formed in this order from the front plate toward the image display unit to produce a vehicle image display function mirror. For the laminate of the circularly polarized light reflecting layer and the quarter wavelength plate, the high retardation plate, the front plate, and the image display unit, the same ones as in Example 8 were used, and the laminated layer of the circularly polarized light reflecting layer and the quarter wavelength plate was used. The body and the high retardation plate, and the high retardation plate and the front plate were each bonded using an OCA sheet (81 series (manufactured by 3M Japan)). Both OCA sheets had a thickness of 25 μm.

The state of the orange peel of the mirror with an image display function for a vehicle manufactured in Comparative Example 2 was D, and the ease of handling was A.

1, 2 Room mirrors 10 and 30 Mirror with image display function for vehicle 11 Frame bodies 12 and 13 Circularly polarized light reflection part 20 Image display part 20a Image display surface 21 Linearly polarized light reflection layer 21a Surface 22 Front plate 23 1/4 wavelength plate 24 First adhesive layer 25 Second adhesive layer 26 Adhesive layer 27 Protective plate 28 High retardation plate 31 1/4 wavelength plate 32 Circularly polarized light reflecting layer 32a Surface 33 Front plate 34 High retardation plate 35 First adhesive layer 36 Second Adhesive layer 37 Adhesive layer 38 Protective plate 100 Mirror 101 with image display function Image display unit 103 Linearly polarized reflective layer 104 1/4 wavelength plate 105 Front plate 106, 107 OCA sheet A User

Claims (15)

A mirror with an image display function for a vehicle including an image display unit capable of displaying a captured image around the vehicle,
In order from the image display unit side, a quarter-wave plate, a dichroic polarization reflection layer on which captured image light displayed on the image display unit is incident, a front plate made of glass or plastic, and an optical compensation layer are arranged. And
The dichroic polarizing reflection layer and the front plate are bonded by a single first adhesive layer, and the front plate and the optical compensation layer are bonded by a single second adhesive layer,
The mirror with an image display function for vehicles, wherein the optical compensation layer is a high retardation plate. The mirror with an image display function for vehicles according to claim 1 whose thickness of said 1st adhesion layer is 10 micrometers or more and 25 micrometers or less. The mirror with a vehicle image display function according to claim 1, wherein the first adhesive layer is an optical transparent adhesive sheet. The mirror with a vehicle image display function according to any one of claims 1 to 3 , wherein a thickness of the second adhesive layer is 10 µm or more and 25 µm or less. The mirror with a vehicle image display function according to any one of claims 1 to 4 , wherein the second adhesive layer is an optical transparent adhesive sheet. The mirror with a vehicle image display function according to any one of claims 1 to 5 , wherein the dichroic polarization reflection layer is a linear polarization reflection layer. The mirror with an image display function for a vehicle according to claim 6 , wherein the linearly polarized light reflecting layer has a multilayer structure in which thin films having different birefringence are alternately laminated. The mirror with an image display function for a vehicle according to any one of claims 1 to 5 , wherein the dichroic polarization reflection layer is a circular polarization reflection layer. The vehicle image display function mirror according to any one of claims 1 to claim 8, hard coating of more than 2H on the opposite side has been subjected to the front plate side of the optical compensation layer. The mirror with an image display function for a vehicle according to any one of claims 1 to 9, wherein a protective plate made of glass or plastic is provided on a side opposite to the front plate side of the optical compensation layer. A claims 1 to any one vehicular image display function method for producing a mirror according to claim 10,
Forming the sheet-like second adhesive layer on the optical compensation layer;
Bonding the front plate on the second adhesive layer;
Forming the sheet-like first adhesive layer on the front plate;
A method for producing a mirror with an image display function for a vehicle, wherein the dichroic polarization reflection layer is bonded onto the first adhesive layer. The manufacturing method of the mirror with an image display function for vehicles according to claim 11 whose thickness of said 1st adhesion layer is 10 micrometers or more and 25 micrometers or less. The method for producing a mirror with an image display function for a vehicle according to claim 11 or 12 , wherein the first adhesive layer is an optical transparent adhesive sheet. The method of manufacturing a mirror with an image display function for a vehicle according to any one of claims 11 to 13 , wherein a thickness of the second adhesive layer is 10 µm or more and 25 µm or less. The method for manufacturing a mirror with an image display function for a vehicle according to any one of claims 11 to 14 , wherein the second adhesive layer is an optical transparent adhesive sheet.