JP2021144207A - Optical laminate and image display device - Google Patents

Abstract

To provide an image display device which exhibits an appearance matching the design of surrounding parts when not turned on, and is capable of displaying a precision image when turned on.SOLUTION: An optical laminate is provided, having polarization characteristics with a metric saturation of reflected light that is 2 or greater and 1.36 times a metric saturation of transmitted light in the SCI method.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical laminate and an image display device including the optical laminate.

In recent years, electrical appliances and in-vehicle equipment have become more sophisticated, and the mounting area of display screens such as operation screens and monitor screens tends to increase. Since the display screen is usually observed in black when it is not displayed, it may not be compatible with the design of the peripheral portion of the housing or the like, and the overall design may be deteriorated.

On the other hand, Patent Documents 1 to 3 propose a method of making it difficult to recognize the difference between the appearance of the display screen and the design of the peripheral portion, thereby improving the design as a whole. However, with the conventional technology, it is difficult to realize a display screen that exhibits an appearance in harmony with the design of the peripheral portion when not displayed and can clearly display an image by the image display device when displayed.

Japanese Unexamined Patent Publication No. 2018-128581 Japanese Unexamined Patent Publication No. 2019-120383 WO2015 / 141350 A1

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is to exhibit an appearance in harmony with the design of the peripheral portion when not displayed, and to clarify an image by an image display device when displayed. The purpose is to realize a display screen that can be displayed on.

According to one aspect of the present invention, an optical laminate having polarization characteristics in which the metric saturation of reflected light in the SCI method is 2 or more and exceeds 1.36 times the metric saturation of transmitted light. Provided.
In one embodiment, the difference between the metric saturation of the reflected light and the metric saturation of the transmitted light is 5 or more.
In one embodiment, the optical laminate comprises a first polarizing element containing a first dichroic material, a light transmitting reflector, and a second polarizing element containing a second dichroic material. , In this order, the single transmittance of the second polarizer is 40% or more, the degree of polarization is 97.0% or more, the absorption axis direction of the first polarizer and the second polarizer. They are arranged so that they are substantially parallel to the absorption axis direction of the polarizer.
In one embodiment, the single transmittance of the light transmissive reflector is 10% to 70%.
In one embodiment, the light transmissive reflector comprises a reflective polarizer.
In one embodiment, the reflection axis direction of the reflection type polarizer and the absorption axis direction of the first polarizer are substantially parallel, and the reflection axis direction of the reflection type polarizer and the first The direction of the absorption axis of the polarizer of 2 is arranged so as to be substantially parallel to each other.
According to another aspect of the present invention, there is provided an image display device including the above optical laminate.

According to the present invention, it is possible to realize a display screen which exhibits an appearance in harmony with the design of the peripheral portion when not displayed and can clearly display an image by an image display device when displayed.

It is the schematic sectional drawing of the optical laminated body by one Embodiment of this invention. It is a schematic perspective view of an example of a reflective polarizer that can be used in the present invention. It is a schematic cross-sectional view of the image display device according to one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

A. Definition of terms (1) The expression "substantially orthogonal" includes the case where the angle between the two directions is 90 ° ± 10 °, preferably 90 ° ± 7 °, and more preferably 90 °. It is ± 5 °. Further, the term "orthogonal" in the present specification may include a substantially orthogonal state.
(2) The expression "substantially parallel" includes the case where the angle formed by the two directions is 0 ° ± 10 °, preferably 0 ° ± 7 °, and more preferably 0 ° ± 5 °. Is. Further, the term "parallel" in the present specification may include a substantially parallel state.
(3) The terms "layer", "board", "sheet" and "film" are not distinguished from each other based solely on the difference in designation. For example, the term "layer" is a concept that includes members that can be called "plates", "sheets", "films".

B. Optical Laminates According to one aspect of the present invention, an optical laminate having polarization characteristics, the metric saturation of reflected light in the SCI method is 2 or more, and the metric saturation of transmitted light is 1. An optical laminate of more than .36 times is provided. As described above, in the optical laminate according to the embodiment of the present invention, the metric saturation of the reflected light in the SCI method when observed from one main surface side is 2 or more, and the metric saturation of the transmitted light is high. It exceeds 1.36 times. The optical laminate is typically applied to an image display device having an optical cell such as a liquid crystal display device including a liquid crystal cell and an organic EL display device having an organic electroluminescence (EL) cell. At this time, the optics are arranged so that the metric saturation of the reflected light in the SCI method when observed from the visual side is 2 or more and exceeds 1.36 times the metric saturation of the transmitted light. The laminated body can function as a polarizing plate (designable polarizing plate) that exhibits a polarization characteristic and imparts a desired design (color, pattern, character, etc.) to the display screen. The metric saturation is ^{a value obtained by the following equation using the a *} value and b ^{* value in the L *} a ^* b ^* color system, and is the distance from the central axis (achromatic axis) of the color space. show.
Metric saturation (C ^* ) = √ (a ^{* 2} + b ^{* 2} )

The metric saturation of the reflected light of the optical laminate (hereinafter, the metric saturation of the reflected light ^{may be referred to as “RC *} ”) is 2 or more as described above. When RC ^* is 2 or more, the light reflected by the optical laminate can be visually recognized as light having a certain color or more. RC ^* is preferably 5 or more, more preferably 10 or more, and even more preferably 20 or more. The maximum value of RC ^* can be, for example, 80.

The metric saturation of the reflected light (RC ^* ) of the optical laminate exceeds 1.36 times the metric saturation of the transmitted light (hereinafter, the metric saturation of the transmitted light may be referred to ^{as "TC *").} , It is preferably 1.5 times or more, more preferably 2.0 times or more, still more preferably 3.0 times or more, and even more preferably 5.0 times or more. According to the image display device in which the optical laminate in which RC ^* and TC ^* satisfy such a relationship is arranged on the visual side of the optical cell, when the power is turned off, the display screen is derived from the optical laminate. When the design is satisfactorily visually recognized and the power is turned on, the influence of the design derived from the optical laminate is suppressed, and the display by the image display device can be satisfactorily visually recognized. RC ^* can be, for example, 27.7 times or less of ^{TC *.}

^{The difference (RC *} -TC ^* ) between the metric saturation of the reflected light and the metric saturation of the transmitted light of the optical laminate is preferably 0 or more, more preferably 3 or more, still more preferably 5 or more. It is even more preferably 8 or more, even more preferably 10 or more, and even more preferably 20 or more. When RC ^* and TC ^* satisfy such a relationship, the light transmitted through the optical laminate has a certain degree of achromaticity or more higher than the light reflected by the optical laminate. Therefore, for example, according to the image display device in which the optical laminate is arranged on the visual side of the optical cell, the design derived from the optical laminate is satisfactorily visually recognized when the power is turned off, and when the power is turned on. The influence of the design derived from the optical laminate is suppressed, and the display by the image display device can be visually recognized well. RC ^* -TC ^* can be, for example, 47.7 or less.

Metric chroma of the transmitted light of the optical stack (TC ^*) can be appropriately set in consideration of the relationship between the RC ^{* (RC *} / TC ^* and ^RC * -TC ^*) and the like. The TC ^* is, for example, 20 or less, preferably 15 or less, more preferably 10 or less, still more preferably 8 or less, and even more preferably 5 or less. When the TC ^* is such a value, the influence of the color derived from the optical laminate is reduced when the light transmitted through the optical laminate is visually recognized, and the light transmission can be improved. The minimum value of TC ^* can be 1, for example.

The simple substance transmittance of the optical laminate is, for example, 15% or more, preferably 20% or more, and more preferably 25% or more. Further, the simple substance transmittance can be, for example, 50% or less, or 45% or less, for example. The degree of polarization of the optical laminate is, for example, 97.0% or more, preferably 99.0% or more, and more preferably 99.9% or more. By having such a transmittance and a degree of polarization, it is possible to clearly display an image by an image display device when the power is turned on.

B-1. Overall Configuration of Optical Laminates FIG. 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. In the optical laminate 100, a first polarizer 10 containing a first dichroic substance, a light transmitting reflector 20, and a second polarizing element 30 containing a second dichroic substance are arranged in this order. It is arranged so that the absorption axis direction of the first polarizer 10 and the absorption axis direction of the second polarizer 30 are substantially parallel to each other. Here, the simple substance transmittance of the second polarizer 30 is preferably 40% or more, and the degree of polarization is preferably 97.0% or more. Typically, when observed from the first polarizer 10 side, the metric saturation of the reflected light of the optical laminate 100 in the SCI method is 2 or more, and the metric saturation of the transmitted light is 1. It exceeds .36 times. As described above, the optical laminate 100 is typically applied to an image display device having an optical cell such as a liquid crystal display device having a liquid crystal cell and an organic EL display device having an organic EL cell. The light transmissive reflector 20 is arranged on the visible side of the optical cell so as to be on the visible side of the second polarizer 30. According to such a configuration, when the power of the image display device is turned off, the first dichroic substance is contained by utilizing the external light (reflected light) reflected by the light transmitting reflector 20. The design caused by the polarizer 10 can be visually recognized satisfactorily. Therefore, by selecting the first dichroic substance according to the desired design, the screen when the power is turned off can be made into the desired design. On the other hand, when the power of the image display device is ON and light is incident from the optical cell side, the linearly polarized light transmitted through the second polarizing element is transmitted through the light transmitting reflector 20 to be the first polarized light. It is incident on the child. At this time, since the absorption axes of the first polarizer and the absorption axes of the second polarizer are parallel to each other (in other words, the transmission axes of both are parallel to each other), the second polarizer is used. The transmitted linearly polarized light can transmit the first polarizer without being subjected to the change in hue due to the first dichroic substance. As a result, an image in which the coloring caused by the first dichroic substance is suppressed can be clearly displayed.

In the illustrated example, the first protective layer 42 and the second protective layer 44 are arranged on the opposite side of the light transmissive reflector 20 and the light transmissive reflector 20 side of the first polarizer 10, respectively. A third protective layer 46 and a fourth protective layer 48 are arranged on the light transmitting reflector 20 side and the opposite side of the second polarizing element 30, respectively. The first protective layer to the fourth protective layer may be omitted depending on the purpose. Further, as long as the effect of the present invention can be obtained, any appropriate suitable between the first polarizer and the light transmissive reflector and / or between the light transmissive reflector and the second polarizer. Optical members and air layers can be arranged.

Each member constituting the optical laminate 100 can be laminated to an adjacent member via any suitable adhesive layer or without an adhesive layer. Examples of the adhesive layer include an adhesive layer or an adhesive layer. Further, on the side of the fourth protective layer 48 opposite to the side on which the second polarizer 30 is arranged, an adhesive layer or the like for bonding the optical laminate 100 to the adjacent member is provided, if necessary. May be done.

In one embodiment, the optical laminate includes a first polarizer, a light transmissive reflector, and a second polarizer in this order, and the first to second polarizers are integrated. It can have a polarized configuration. The integration of each member can be done, for example, via an adhesive layer. The optical laminate 100 according to the embodiment is, for example, a polarizing plate including a first polarizing element 10 and optionally a first protective layer 42 and / or a second protective layer 44 (hereinafter, referred to as a first polarizing plate). A polarizing plate including a light transmissive reflector 20 and a polarizing plate including a second polarizer 30 and optionally a third protective layer 46 and / or a fourth protective layer 48 (hereinafter referred to as a first). (Sometimes referred to as a polarizing plate of 2) and may have a configuration in which they are integrated in this order via an adhesive layer.

In another embodiment, the optical laminate comprises a first polarizer, a light transmissive reflector, and a second polarizer in that order, with the first polarizer and the light transmissive reflector, and /. Alternatively, the light transmissive reflector and the second polarizer may have a structure in which they are separably arranged (a structure in which they are not integrated via an adhesive layer). The optical laminate 100 in the embodiment may have, for example, a configuration in which the first polarizing plate, the light transmissive reflector 20, and the second polarizing plate are arranged in this order without interposing an adhesive layer. Further, for example, in the optical laminate 100 in the embodiment, the first polarizing plate and the light transmissive reflector 20 are integrated via an adhesive layer, and the integrated laminate is a second polarized light. It may have a configuration in which it is arranged on one side (visual side) of the plate without interposing an adhesive layer. Further, for example, in the optical laminate 100 of the embodiment, the light transmissive reflector 20 and the second polarizing plate are integrated via an adhesive layer, and the first polarizing plate is integrated with the laminated laminate. It may have a configuration in which the light-transmitting reflector 20 side of the body is arranged without an adhesive layer.

B-2. First Polarizer The first polarizer is an absorption-type polarizer containing a first dichroic substance. The first dichroic substance can be appropriately selected according to the color and pattern of the design desired for the optical laminate. As the first dichroic substance, one kind of dichroic substance may be used alone, or two or more kinds of dichroic substances may be used in combination. As the first dichroic substance, iodine or a dichroic dye other than iodine can be used.

Specific examples of bicolor dyes other than iodine include bicolor direct dyes composed of disuazo compounds, bicolor direct dyes composed of trisazo and tetrakisazo compounds, liquid crystal azo dyes, polycyclic dyes, and sulfones. Examples include (azo) dyes having an acid group. Specific examples of the dichroic dye include C.I. I. direct. Yellow 12, C.I. I. direct. Yellow 28, C.I. I. direct. Yellow 44, C.I. I. direct. Yellow 142; C.I. I. direct. Orange 26, C.I. I. direct. Orange 39, C.I. I. direct. Orange 71, C.I. I. direct. Orange 107; C.I. I. direct. Red 2, C.I. I. direct. Red 31, C.I. I. direct. Red 39, C.I. I. direct. Red 79, C.I. I. direct. Red 81, C.I. I. direct. Red 117, C.I. I. direct. Red 247; C.I. I. direct. Green 80, C.I. I, direct. Green 59; C.I. I. Direct Blue 1, C.I. I. Direct Blue 71, C.I. I. Direct Blue 78, C.I. I. Direct Blue 168, C.I. I. Direct Blue 202; C.I. I. Direct Violet 9, C.I. I. Direct Violet 51; C.I. I. Direct Brown 106, C.I. I. Direct Brown 223 can be mentioned. Further, depending on the purpose, dyes developed for polarizing films as disclosed in WO2009 / 057676, WO2007 / 145210, WO2006 / 057214 and JP-A-2004-251963 can also be used. These dyes are used as free acids, alkali metal salts (for example, Na salt, K salt, Li salt), ammonium salts, and amine salts.

In one embodiment, the first polarizer is typically composed of a resin film, particularly a polyvinyl alcohol (PVA) -based resin film. Any suitable configuration can be adopted as the resin film. For example, the resin film forming the polarizer may be a single-layer resin film or a laminated body having two or more layers.

Specific examples of the polarizer composed of a single-layer resin film include highly hydrophilic films such as polyvinyl alcohol (PVA) -based resin films, partially formalized PVA-based resin films, and ethylene / vinyl acetate copolymerization-based partially saponified films. Examples of the molecular film include those which have been dyed and stretched with a bicolor dye.

Dyeing with the dichroic dye is performed, for example, by immersing a PVA-based resin film in an aqueous solution of the dichroic dye. The content of the bicolor dye in the aqueous solution is, for example, 1 × 10 ^-4 parts by weight to 10 parts by weight, preferably 1 × 10 ^-3 parts by weight to 1 part by weight, more preferably 1 part by weight, per 100 parts by weight of water. is 1 × ^{10 -2} parts by weight to 1 parts by weight. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. When a bicolor dye is used, the temperature of the aqueous dye solution used for dyeing is usually 20 ° C. to 80 ° C., and the immersion time (dyeing time) in the aqueous solution is usually 10 seconds to 1800 seconds.

Further, for example, dyeing with the above dichroic dye can be performed by coating or printing. By dyeing by coating or printing, a fine design (design, character, etc.) can be suitably imparted to the first polarizer. The coating method and the printing method are not particularly limited as long as the effects of the present invention can be obtained, but an inkjet printing method, a screen printing method and the like can be preferably used.

The stretching ratio of the stretching treatment is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or while dyeing. Alternatively, it may be stretched and then dyed. If necessary, the PVA-based resin film is subjected to a swelling treatment, a cross-linking treatment, a cleaning treatment, a drying treatment and the like. For example, by immersing the PVA-based resin film in water and washing it with water before dyeing, it is possible not only to clean the dirt and blocking inhibitor on the surface of the PVA-based resin film, but also to swell and dye the PVA-based resin film. It is possible to prevent unevenness and the like.

Specific examples of the polarizer obtained by using the laminate include a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a resin base material and the resin. Examples thereof include a polarizer obtained by using a laminate with a PVA-based resin layer coated and formed on a base material. The polarizer obtained by using the laminate of the resin base material and the PVA-based resin layer coated and formed on the resin base material is, for example, a resin base material obtained by applying a PVA-based resin solution to the resin base material and drying the resin base material. It is produced by forming a PVA-based resin layer on the PVA-based resin layer to obtain a laminate of a resin base material and a PVA-based resin layer; stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. obtain. In the present embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Further, stretching may further include, if necessary, stretching the laminate in the air at a high temperature (eg, 95 ° C. or higher) prior to stretching in boric acid aqueous solution. The obtained resin base material / polarizer laminate may be used as it is without peeling off the resin base material (as a result, the resin base material functions as a protective layer), is laminated on a protective film, and then the resin is used. By peeling off the base material, it may be in the form of a first polarizer / protective layer. Further, as the dyeing method, the same method as the dyeing method for a polarizer composed of a single-layer resin film, for example, dipping, coating, printing or the like can be used.

Details of the method for producing a polarizer obtained by subjecting a resin film to a dyeing treatment and a stretching treatment with a dichroic dye are described in, for example, Japanese Patent Application Laid-Open No. 06-066001, Japanese Patent Application Laid-Open No. 2012-73580, and Japanese Patent Application Laid-Open No. 2018-22125. It is described in the publication. The entire description of the publication is incorporated herein by reference.

In another embodiment, the first polarizer may be a liquid crystal coating type polarizer formed from a liquid crystal compound. The liquid crystal coating type polarizer can be produced, for example, by coating a liquid crystal composition containing a liquid crystal compound on a base material. An alignment film may be formed on the base material before applying the liquid crystal composition. The alignment film can be formed, for example, by imparting orientation to a coating film formed by coating the alignment film forming composition on a substrate by rubbing, polarization irradiation, or the like.

The liquid crystal composition may contain a liquid crystal compound and a first dichroic substance, or may contain a liquid crystal compound having dichroism (in the latter, the liquid crystal compound). Also serves as the first dichroic substance). The liquid crystal composition can further contain an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a cross-linking agent, a silane coupling agent and the like. Any compound contained in the liquid crystal composition may have a polymerizable functional group.

As the liquid crystal compound having a dichroism, an azo dye exhibiting a lyotropic liquid crystal property can be preferably used. Specific examples of the azo dye exhibiting lyotropic liquid crystal properties and a method for producing a liquid crystal-coated polarizer using the azo dye are described in JP-A-2019-079040, JP-A-2019-079041 and JP-A-2019-079042. It is described in Japanese Patent Application Laid-Open No. 2019-087666 and the like, and the entire description of these publications is incorporated herein by reference. Further, patents have been provided on a method for producing a light absorption anisotropic film having an excellent two-color ratio using a liquid crystal composition having nematic liquid crystal property and smectic liquid crystal property, and in particular, smectic B liquid crystal property, and specific examples of liquid crystal materials. It is described in Japanese Patent No. 4937252, Japanese Patent No. 5364304, etc., and the entire description of these publications is incorporated herein by reference.

The thickness of the first polarizer when composed of a resin film is preferably 40 μm or less, more preferably 30 μm or less, and further preferably 10 μm or less. The lower limit of the thickness can be, for example, 2 μm.

The thickness of the first polarizer in the case of a liquid crystal coating type polarizer is preferably 5 μm or less, more preferably 1 μm or less, and further preferably 500 nm or less. The lower limit of the thickness is 10 nm in one embodiment.

The first polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The simple substance transmittance of the polarizer is, for example, 10% to 90%, preferably 10% to 80%, and more preferably 20% to 70%. The degree of polarization of the first polarizer is, for example, 15% or more, preferably 40% or more, more preferably 80% or more, still more preferably 90% or more. The single transmittance and / or the degree of polarization may be substantially uniform or different in the plane. For example, when the design of the first polarizer includes a shade of color or a pattern, the single transmittance and / or the degree of polarization in the plane may differ depending on the design.

The simple substance transmittance (Ts) and the degree of polarization referred to in the present specification can be measured using a spectrophotometer. Specifically, for the degree of polarization, the parallel transmittance Tp and the orthogonal transmittance Tc of the polarizer are measured using a spectrophotometer, and the formula: degree of polarization (%) = {(Tp-Tc) / (Tp + Tc)} It can be obtained from ^{1/2 × 100.} These Ts, Tp and Tc are Y values measured by the JIS Z8701 two-degree visual field (C light source) and corrected for luminosity factor.

B-3. Light-transmitting reflector The light-transmitting reflector has transmission characteristics and reflection characteristics that reflect a part of incident light and transmit the remaining light. The single transmittance of the light transmissive reflector is preferably 10% to 70%, more preferably 15% to 65%, and further preferably 20% to 60%. The reflectance of the light-transmitting reflector is preferably 30% or more, more preferably 40% or more, still more preferably 45% or more. As the light transmissive reflector, for example, a half mirror, a reflective polarizer, a louver film, or the like can be used.

As the half mirror, for example, a multilayer laminate in which two or more dielectric films having different refractive indexes are laminated can be used. Such half mirrors preferably have a metallic luster.

Examples of the material for forming the dielectric film include metal oxides, metal nitrides, metal fluorides, thermoplastic resins (for example, polyethylene terephthalate (PET)) and the like. The multilayer laminated body of the dielectric film reflects a part of the incident light at the interface due to the difference in the refractive index of the laminated dielectric films. The reflectance can be adjusted by changing the phase of the incident light and the reflected light according to the thickness of the dielectric film and adjusting the degree of interference between the two lights. The thickness of the half mirror made of a multilayer laminate of dielectric films can be, for example, 50 μm to 200 μm. As such a half mirror, for example, a commercially available product such as the trade name "Picassus" manufactured by Toray Industries, Inc. can be used.

The half mirror includes, for example, aluminum (Al), indium (In), zinc (Zn), lead (Pb), copper (Cu), silver (Ag), or an alloy thereof on a resin film such as PET. A metal-deposited film on which a metal such as the above is vapor-deposited can be used. The metal-deposited film has a metal-like luster due to reflection when observed from the vapor-deposited film side, but can transmit light from the resin film side, and by changing the vapor-deposited film thickness, the light transmittance Can be controlled. The vapor deposition film thickness is preferably 1 nm to 50 nm, more preferably 10 nm to 30 nm. The film thickness of the resin film is preferably 1 μm to 1000 μm, more preferably 20 μm to 100 μm.

The reflective polarizer has a function of transmitting polarized light in a specific polarized state (polarizing direction) and reflecting light in other polarized states. The reflective polarizer may be a linearly polarized light-separated type or a circularly polarized light-separated type, but a linearly polarized light-separated type is preferable. In the linearly polarized light separation type reflection type polarizer, the direction of the reflection axis is substantially parallel to the absorption axis direction of the absorption type polarizer (specifically, the first polarizer and the second polarizer). Be placed. Hereinafter, as an example, a linearly polarized light separation type reflective polarizer will be described. Examples of the circularly polarized light separation type reflective polarizer include a laminate of a film on which a cholesteric liquid crystal is immobilized and a λ / 4 plate.

FIG. 2 is a schematic perspective view of an example of a reflective polarizer. The reflective polarizer is a multilayer laminate in which a layer A having birefringence and a layer B having substantially no birefringence are alternately laminated. For example, the total number of layers of such a multi-layer laminate can be 50-1000. In the illustrated example, the refractive index nx in the x-axis direction of the A layer is larger than the refractive index ny in the y-axis direction, and the refractive index nx in the x-axis direction of the B layer and the refractive index ny in the y-axis direction are substantially the same. be. Therefore, the difference in refractive index between the A layer and the B layer is large in the x-axis direction and substantially zero in the y-axis direction. As a result, the x-axis direction becomes the reflection axis, and the y-axis direction becomes the transmission axis. The difference in refractive index between the A layer and the B layer in the x-axis direction is preferably 0.2 to 0.3. The x-axis direction corresponds to the stretching direction of the reflective polarizer in the manufacturing method described later.

The layer A is preferably composed of a material that exhibits birefringence by stretching. Representative examples of such materials include polyester naphthalenedicarboxylic acid (eg, polyethylene naphthalate), polycarbonate and acrylic resins (eg, polymethylmethacrylate). Polyethylene naphthalate is preferred. The B layer is preferably composed of a material that does not substantially exhibit birefringence even when stretched. A typical example of such a material is a copolyester of naphthalenedicarboxylic acid and terephthalic acid.

The reflective polarizing element transmits light having a first polarization direction (for example, a p wave) at the interface between the A layer and the B layer, and has a second polarization direction orthogonal to the first polarization direction. Reflects light (eg, s waves). At the interface between the A layer and the B layer, the reflected light is partially transmitted as light having a first polarization direction and partially reflected as light having a second polarization direction. By repeating such reflection and transmission in large numbers inside the reflective polarizer, the efficiency of light utilization can be improved.

In one embodiment, the reflective polarizer may include a reflective layer R as the outermost layer on the side opposite to the viewing side, as shown in FIG. By providing the reflective layer R, it is possible to further utilize the light that has returned to the outermost side of the reflective polarizer without being finally utilized, so that the efficiency of light utilization can be further improved. The reflective layer R typically exhibits a reflective function due to the multilayer structure of the polyester resin layer.

The overall thickness of the reflective polarizer can be appropriately set according to the purpose, the total number of layers contained in the reflective polarizer, and the like. The overall thickness of the reflective polarizer is preferably 10 μm to 150 μm.

Reflective polarizers can typically be made by combining coextrusion and transverse stretching. Coextrusion can be done in any suitable manner. For example, it may be a feed block system or a multi-manifold system. For example, the material forming the A layer and the material forming the B layer are extruded in the feed block, and then multi-layered using a multiplier. Such a multi-layer device is known to those skilled in the art. Next, the obtained elongated multilayer laminate is typically stretched in a direction (TD) orthogonal to the transport direction. The material (for example, polyethylene naphthalate) constituting the layer A has an increased refractive index only in the stretching direction due to the lateral stretching, and as a result, exhibits birefringence. The refractive index of the material constituting the B layer (for example, copolyester of naphthalene dicarboxylic acid and terephthalic acid) does not increase in any direction by the transverse stretching. As a result, a reflective polarizer having a reflection axis in the stretching direction (TD) and a transmission axis in the transport direction (MD) can be obtained (TD corresponds to the x-axis direction of FIG. 2 and MD corresponds to the y-axis). Corresponds to the direction). The stretching operation can be performed using any suitable device.

As the reflective polarizer, for example, those described in JP-A-9-507308 can be used. Further, as the reflective polarizer, a commercially available product may be used as it is, or the commercially available product may be used after secondary processing (for example, stretching). Examples of commercially available products include the product name "APCF" manufactured by Nitto Denko Corporation, the product name "DBEF" manufactured by 3M Company, and the product name "APF" manufactured by 3M Company.

B-4. Second Polarizer The second polarizer is an absorption-type polarizer containing a second dichroic substance. As the second dichroic substance, the same substance as the first dichroic substance can be exemplified, and iodine can be preferably used.

In one embodiment, the second polarizer is composed of a resin film containing a second dichroic material (eg, iodine). The resin film forming the polarizer may be a single-layer resin film or a laminated body having two or more layers. As the resin forming the resin film, a PVA-based resin is preferably used. As a method for producing a second polarizer composed of a resin film containing iodine, a resin film which is a single layer or a laminate of two or more layers is stretched and dyed, and the resin film is used as a polarizer. The including method can be exemplified, and the dyeing is preferably carried out by immersing the resin film in an aqueous solution containing iodine. As a method for producing the second polarizer, for example, the methods described in JP2012-73580A, Patent No. 6470455 and the like can be preferably used.

The thickness of the second polarizer is preferably 40 μm or less, more preferably 30 μm or less. Further, the lower limit of the thickness may be, for example, 2 μm, or for example, 3 μm.

The second polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The simple substance transmittance of the second polarizer is, for example, 40% to 46.0%, preferably 42% to 46.0%. The degree of polarization of the second polarizer is preferably 97.0% or more, more preferably 99.0% or more, still more preferably 99.9% or more.

B-5. Protective Layer The first to fourth protective layers are formed of any suitable film that can be used as a protective layer for the polarizer. Specific examples of the material that is the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based. , Polystyrene-based, polycarbonate-based, polyolefin-based, (meth) acrylic-based, acetate-based transparent resins and the like. Further, thermosetting resins such as (meth) acrylic, urethane, (meth) acrylic urethane, epoxy, and silicone, or ultraviolet curable resins can also be mentioned. In addition to this, for example, a vitreous polymer such as a siloxane-based polymer can also be mentioned. Further, the polymer film described in JP-A-2001-343529 (WO01 / 37007) can also be used. As the material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. Can be used, and examples thereof include a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. The polymer film can be, for example, an extruded product of the above resin composition.

In one embodiment, as the (meth) acrylic resin, a (meth) acrylic resin having a cyclic structure such as a lactone ring or a glutarimide ring in the main chain is used. Examples of the (meth) acrylic resin having a glutarimide ring (hereinafter, also referred to as glutarimide resin) include JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, and JP-A. 2006-328334, 2006-337491, 2006-337492, 2006-337493, 2006-337569, 2007-009182, 2009- It is described in Japanese Patent Application Laid-Open No. 161744 and Japanese Patent Application Laid-Open No. 2010-284840. These statements are incorporated herein by reference.

When the optical laminate 100 is applied to an image display device, the thickness of the first protective layer (outer protective layer) arranged on the visual side of the first polarizer is typically 300 μm or less, which is preferable. Is 100 μm or less, more preferably 5 μm to 80 μm, still more preferably 10 μm to 60 μm. When the surface treatment is applied, the thickness of the outer protective layer is the thickness including the thickness of the surface treatment layer. Examples of the surface treatment layer include a light diffusion layer and a hard coat layer. When the outer protective layer has a light diffusing layer, it is possible to realize a display screen that exhibits a metallic opaque gloss when the image display device is hidden.

When the optical laminate 100 is applied to an image display device, the thickness of the second, third, and fourth protective layers arranged on the optical cell side of the first polarizer is preferably 5 μm to 200 μm, more preferably. Is 10 μm to 100 μm, more preferably 10 μm to 60 μm. In one embodiment, the fourth protective layer is a retardation layer with any suitable retardation value. In this case, the in-plane retardation Re (550) of the retardation layer is, for example, 110 nm to 150 nm. “Re (550)” is an in-plane phase difference measured with light having a wavelength of 550 nm at 23 ° C., and is obtained by the formula: Re = (nx−ny) × d. Here, "nx" is the refractive index in the direction in which the in-plane refractive index is maximized (that is, the slow-phase axis direction), and "ny" is the in-plane direction orthogonal to the slow-phase axis (that is, phase-advance). It is the refractive index in the axial direction), “nz” is the refractive index in the thickness direction, and “d” is the thickness (nm) of the layer (film).

C. Image display device The optical laminate according to item B above can be applied to an image display device. Therefore, the present invention includes an image display device including the above optical laminate. Typical examples of the image display device include a liquid crystal display device provided with a liquid crystal cell, an organic EL display device provided with an organic electroluminescence (EL) cell, and the like. In one embodiment, the optical laminate is arranged on the visual side of an optical cell such as a liquid crystal cell or an organic EL cell so that the light transmissive reflector is on the visual side of the second polarizer. Since the liquid crystal cell and the organic EL cell are not characteristic parts of the present invention and can adopt a configuration well known in the industry, detailed description thereof will be omitted.

FIG. 3 is a schematic cross-sectional view of a liquid crystal display device according to one embodiment of the present invention. The liquid crystal display device 200 includes a liquid crystal panel 160 and a backlight unit 180 having an optical laminate 100, a liquid crystal cell 120, and a third polarizer 140 in this order from the visual side. The optical laminate 100 is the optical laminate according to the item B, so that the light transmissive reflector 20 is on the visual side of the second polarizer 30 and the absorption shaft of the second polarizer 30. And the absorption axis of the third polarizer 140 are arranged so as to be substantially orthogonal to each other. As the third polarizer, the same one as that of the second polarizer can be used.

As a modification of the liquid crystal display device illustrated in FIG. 3, a second polarizer 30 and a liquid crystal cell 120 are used instead of the liquid crystal panel 160 having the optical laminate 100, the liquid crystal cell 120, and the third polarizer 140. A liquid crystal panel having the above and the third polarizer 140 can be used. In this case, the light transmissive reflector 20 and the first polarizer 10 are arranged in this order on the visible side (second polarizer side) of the liquid crystal panel toward the visible side. If necessary, adjacent members may be bonded to each other via an adhesive layer. The liquid crystal display device thus obtained is also included in the image display device including the optical laminate according to the item A.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The measurement method of each characteristic is as follows. Unless otherwise specified, "parts" and "%" in Examples and Comparative Examples are based on weight.

(1) Thickness Measured using a digital gauge (manufactured by Ozaki Seisakusho Co., Ltd., product name "PEACOCK").
^{(2) Reflective Hue and Metric Saturation of Optical Laminates From the reflected hues a *} and b ^* measured with a spectrophotometer (manufactured by Konica Minolta, product name "CM-2600d"). The metric saturation was calculated using the following formula. At the time of measurement, the surface of the optical laminate opposite to the second polarizer (in the optical laminate of the embodiment, the surface of the first polarizer) was used as the measurement surface.
Metric saturation (C ^* ) = √ (a ^{* 2} + b ^{* 2} )
(3) Transmitted Hue of Optical Laminate The hue of the L * a * b * color system is obtained from the single spectrum of the optical laminate obtained using an ultraviolet-visible near-infrared spectrophotometer (V-7100 manufactured by JASCO Corporation). The calculation was performed, and the metric saturation was obtained using the same formula as in (2) above. At this time, the transmission spectrum from the second polarizer side of the optical laminate to the opposite side (in the optical laminate of the example, the second polarizer side to the first polarizer side) was measured.
(4) Single Transmittance and Degree of Polarization of Polarizer For the iodine-based polarizer, the polarizing plate A (iodine-based polarizer / protective layer) obtained in Production Example 1 was used as an ultraviolet-visible near-infrared spectrophotometer (Japan). The single transmittance Ts, the parallel transmittance Tp, and the orthogonal transmittance Tc measured using V-7100) manufactured by Spectronizing Co., Ltd. were defined as the polarizers Ts, Tp, and Tc, respectively. These Ts, Tp and Tc are Y values measured by the JIS Z8701 2 degree field of view (C light source) and corrected for luminosity factor. From the obtained Tp and Tc, the degree of polarization was determined using the following formula.
Polarization degree (%) = {(Tp-Tc) / (Tp + Tc)} ^1/2 × 100
The dyed polarizers obtained in Production Examples 2 to 5 were also measured by the same method.
(5) Single transmittance of optical laminate or colored pressure-sensitive adhesive sheet When the optical laminate or colored pressure-sensitive adhesive sheet was measured using an ultraviolet-visible near-infrared spectrophotometer (V-7100 manufactured by JASCO Corporation), The transmittance Ts having a wavelength of 380 nm to 780 nm was defined as a single transmittance Ts. This Ts is a Y value measured by a JIS Z8701 double field of view (C light source) and corrected for luminosity factor.
(6) Single Transmittance of Light Transmitting Reflector A wavelength of 380 nm when the light transmitting reflector is measured using an ultraviolet-visible near-infrared spectrophotometer (U-4100 or UH-4150 manufactured by Hitachi High-Tech Science). The single transmittance Ts of about 780 nm was defined as the single transmittance Ts of the light transmitting reflector. This Ts is a Y value measured by a JIS Z8701 double field of view (C light source) and corrected for luminosity factor.

<Production Example 1 Fabrication of a polarizing plate containing an iodine-based polarizer>
As the thermoplastic resin base material, an amorphous isophthal copolymer polyethylene terephthalate film (thickness: 100 μm) having a long shape and a Tg of about 75 ° C. was used, and one side of the resin base material was subjected to corona treatment.
100 parts by weight of PVA-based resin in which polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer") are mixed at a ratio of 9: 1. A PVA aqueous solution (coating solution) was prepared by dissolving 13 parts by weight of potassium iodide in water.
The PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60 ° C. to form a PVA-based resin layer having a thickness of 13 μm to prepare a laminate.
The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130 ° C. (aerial auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 40 ° C. (an aqueous boric acid solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Next, in a dyeing bath having a liquid temperature of 30 ° C. (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1: 7 with respect to 100 parts by weight of water), the polarizer finally obtained Immersion was carried out for 60 seconds while adjusting the concentration so that the simple substance transmittance (Ts) became a desired value (dyeing treatment).
Next, it was immersed in a cross-linked bath at a liquid temperature of 40 ° C. (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds. (Crossing treatment).
Then, while immersing the laminate in a boric acid aqueous solution (boric acid concentration 4% by weight, potassium iodide concentration 5% by weight) at a liquid temperature of 70 ° C., the total in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds. Uniaxial stretching was performed so that the stretching ratio was 5.5 times (underwater stretching treatment).
Then, the laminate was immersed in a washing bath at a liquid temperature of 20 ° C. (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
Then, while drying in an oven kept at about 90 ° C., it was brought into contact with a heating roll made of SUS whose surface temperature was kept at about 75 ° C. (dry shrinkage treatment).
In this way, a polarizer having a thickness of about 5 μm was formed on the resin substrate, and a laminate having a resin substrate / iodine-based polarizer was obtained.
An acrylic resin film (thickness: 40 μm) having a lactone ring structure as a protective layer is attached to the surface of the polarizer obtained above (the surface opposite to the resin base material) via an ultraviolet curable adhesive. Matched. Next, the resin base material was peeled off to obtain a polarizing plate A having an iodine-based polarizer / protective layer structure. The single-unit transmittance of the polarizing plate A (substantially an iodine-based polarizing element) was 42.4%, and the degree of polarization was 99.999%.

<Manufacturing Example 2 Production of Red Polarizer>
A red polarizing element in the same manner as in Production Example 1 except that 4 parts of Direct Red 81 (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the dyeing bath instead of iodine with respect to 100 parts by weight of water. Got The simple substance transmittance of the polarizer was 44.4%, and the degree of polarization was 58.6%.

<Manufacturing Example 3 Production of Blue Polarizer>
A blue polarizer was obtained in the same manner as in Production Example 2 except that 4 parts of Direct Blue 1 (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the dichroic dye. The simple substance transmittance of the polarizer was 42.1%, and the degree of polarization was 68.9%.

<Manufacturing Example 4 Production of Yellow Polarizer>
A yellow polarizer was obtained in the same manner as in Production Example 2 except that 4 parts of Direct Yellow 4 (manufactured by Tokyo Chemical Industry Co., Ltd.) were used as the dichroic dye. The simple substance transmittance of the polarizer was 79.9%, and the degree of polarization was 17.9%.

<Manufacturing Example 5 Production of Green Polarizer>
A green polarizer was obtained in the same manner as in Production Example 2 except that 2 parts of Direct Blue 1 (manufactured by Tokyo Kasei Co., Ltd.) and 2 parts of Direct Yellow 4 (manufactured by Tokyo Kasei Co., Ltd.) were used as the dichroic dye. The simple substance transmittance of the polarizer was 60.3%, and the degree of polarization was 42.9%.

<Manufacturing Example 6 Preparation of Red Adhesive Sheet>
≪Preparation of adhesive composition≫
100 parts of a monomer mixture containing 2-ethylhexyl acrylate (2EHA), NVP, and hydroxyethyl acrylate (HEA) in a weight ratio of 78/18/4 as a photopolymerization initiator, trade name: Irgacure 651 (manufactured by Ciba Specialty Chemicals). ) 0.035 parts and trade name: Irgacure 184 (manufactured by Ciba Specialty Chemicals) 0.035 parts and put into a four-necked flask, and the viscosity (BH viscosity meter, No. 5 rotor, 10 rpm, measurement) under a nitrogen atmosphere. A monomer syrup containing a partial polymer of the above-mentioned monomer mixture was prepared by irradiating with ultraviolet rays until the temperature (temperature 30 ° C.) reached about 15 Pa · s and photopolymerizing.
In 100 parts of this monomer syrup, 17.6 parts of hydroxyethyl acrylate (HEA), 5.9 parts of acrylic oligomer, 0.088 part of 1,6-hexanediol diacrylate (HDDA), and 3-glyceride as a silane coupling agent. Sidoxypropyltrimethoxysilane (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.35 part, Ajinomoto Fine-Techno Azisper PB821 as a dispersant, 2,9-Dimethylquinolino [2,3-b] as a pigment A red pressure-sensitive adhesive composition was prepared by blending 0.05 parts by mass of acridine-7,14 (5H, 12H) -diomer (manufactured by BLD Pharmatech Ltd.).

As the above-mentioned acrylic oligomer, one synthesized by the following method was used.
≪Synthesis of acrylic oligomers≫
100 parts of toluene, 60 parts of dicyclopentanyl methacrylate (DCPMA) (trade name: FA-513M, manufactured by Hitachi Kasei Kogyo Co., Ltd.), 40 parts of methyl methacrylate (MMA), and 3.5 parts of α-thioglycerol as a chain transfer agent. Was put into a four-necked flask. Then, after stirring at 70 ° C. in a nitrogen atmosphere for 1 hour, 0.2 part of AIBN was added as a thermal polymerization initiator, and the mixture was reacted at 70 ° C. for 2 hours and then at 80 ° C. for 2 hours. Then, the reaction solution was put into a temperature atmosphere of 130 ° C., and toluene, the chain transfer agent, and the unreacted monomer were dried and removed to obtain a solid acrylic oligomer. The Tg of this acrylic oligomer was 144 ° C. and the Mw was 4300.

≪Preparation of adhesive sheet≫
The red pressure-sensitive adhesive composition obtained above is applied to a release film R1 (MRF # 38, manufactured by Mitsubishi Resin Co., Ltd.) having a thickness of 38 μm in which one side of the polyester film is a release surface, and one side of the polyester film is a release surface. By covering with a 38 μm thick release film R2 (MRE # 38 manufactured by Mitsubishi Resin Co., Ltd.) to block air and irradiating with ultraviolet rays to cure, the thickness is 50 μm and the single transmission rate is 19.3%. , A red pressure-sensitive adhesive sheet (red pressure-sensitive adhesive layer) having a degree of polarization of 0% was formed.

<Manufacturing Example 7 Production of Blue Adhesive Sheet>
Similar to Production Example 6 except that 0.05 parts of blue pigment (manufactured by Tokyo Chemical Industry Co., Ltd., product name "Pigment Blue 15") was used instead of 0.05 parts of red pigment. A blue pressure-sensitive adhesive sheet having a rate of 24.2% and a degree of polarization of 0% was obtained.

<Manufacturing Example 8 Preparation of Yellow Adhesive Sheet>
Similar to Production Example 6, except that 0.05 parts of a yellow pigment (manufactured by Oakwood Products, Inc., product name "Dalamar Yellow") was used instead of 0.05 parts of a red pigment, a single substance having a thickness of 50 μm. A yellow pressure-sensitive adhesive sheet having a transmittance of 57.9% and a degree of polarization of 0% was obtained.

<Manufacturing Example 9 Preparation of Green Adhesive Sheet>
0.03 parts of blue pigment (manufactured by Tokyo Chemical Industry Co., Ltd., product name "Pigment Blue 15") and yellow pigment (manufactured by Oakwood Products, Inc., product name "Dalamar Yellow") 0 instead of 0.05 parts of red pigment A green pressure-sensitive adhesive sheet having a thickness of 50 μm, a single unit transmittance of 43.3%, and a degree of polarization of 0% was obtained in the same manner as in Production Example 6 except that .03 parts were mixed and used.

<Manufacturing Example 10 Fabrication of Protective Film with Light Diffusion Layer>
100 parts by weight of urethane acrylate-based monomer (ultraviolet curable resin, refractive index 1.52), 3 parts by weight of benzophenone-based polymerization initiator, 14 parts by weight of silica powder having an average particle diameter of 4 μm, 3.33 parts by weight of fluoroalkylsilane additive. Parts are added and diluted with toluene to a solid content of 32 parts by weight to prepare a coating solution, the coating solution is stirred with a homogenizer, and the silica powder is completely dispersed to form a light diffusion layer. A coating solution for use was prepared. The coating liquid for forming a light diffusion layer is applied onto a TAC film (manufactured by Fujifilm, product name "TG60UL", thickness: 60 μm), and the coating film is cured by irradiating with ultraviolet rays to achieve a thickness on the TAC film. A 5 μm light diffusing layer was formed. The haze value of the protective film having the light diffusion layer was 41%.

[Example 1]
Reflective polarizer (manufactured by Nitto Denko Co., Ltd., product name "APCF", single transmittance) on the surface of the iodine-based polarizing element of the polarizing plate A obtained in Production Example 1 via an acrylic pressure-sensitive adhesive layer (thickness: 23 μm). : 47%) were laminated to obtain a laminate having a structure of a protective layer / iodine-based polarizing element / reflective polarizer. At this time, the reflection axis of the reflective polarizer and the absorption axis of the iodine-based polarizer were laminated so as to be parallel to each other. On the surface of the reflective polarizer of the obtained laminate, the red polarizing element obtained in Production Example 2 was applied via an acrylic pressure-sensitive adhesive layer (thickness: 23 μm) to the absorption axis direction of the iodine-based polarizer and the red polarizer. They were bonded so that they were parallel to each other in the absorption axis direction. Next, a triacetyl cellulose (TAC) film (manufactured by Fuji Film Co., Ltd., product name "TG60UL", thickness: 60 μm) is attached to the surface of the red polarizing element as a protective layer via an acrylic pressure-sensitive adhesive (thickness: 23 μm). , [Red Polarizer (1st Polarizer) / Reflective Polarizer (Light Transmissive Reflector) / Iodine Polarizer (2nd Polarizer)] was obtained.

[Example 2]
An optical laminate 2 was obtained in the same manner as in Example 1 except that the TAC film with a light diffusing layer obtained in Production Example 10 was bonded to the surface of a red polarizer.

[Example 3]
An optical laminate 3 was obtained in the same manner as in Example 1 except that the blue polarizer obtained in Production Example 3 was used instead of the red polarizer.

[Example 4]
An optical laminate 4 was obtained in the same manner as in Example 1 except that the yellow polarizer obtained in Production Example 4 was used instead of the red polarizer.

[Example 5]
An optical laminate 5 was obtained in the same manner as in Example 1 except that the green polarizer obtained in Production Example 5 was used instead of the red polarizer.

[Example 6]
The optical laminate 6 was formed in the same manner as in Example 1 except that a half mirror (manufactured by Toray Industries, Inc., product name "Picassus", thickness 100 μm, single transmittance: 30%) was used instead of the reflective polarizer. Obtained.

[Example 7]
The optical laminate 7 was used in the same manner as in Example 1 except that a half mirror (manufactured by Toray Industries, Inc., product name "Picassus", thickness 100 μm, single transmittance: 50%) was used instead of the reflective polarizer. Obtained.

[Example 8]
The optical laminate 8 was formed in the same manner as in Example 1 except that a half mirror (manufactured by Toray Industries, Inc., product name "Picassus", thickness 100 μm, single transmittance: 80%) was used instead of the reflective polarizer. Obtained.

[Example 9]
The same as in Example 1 except that a half mirror (a metal-deposited film in which an aluminum-deposited film having a thickness of 13 nm is formed on the surface of a PET film having a thickness of 50 μm, a single-unit transmittance: 11%) was used instead of the reflective polarizer. The optical laminate 9 was obtained.

[Comparative Example 1]
Reflective polarizer (manufactured by Nitto Denko Co., Ltd., product name "APCF", single transmittance) on the surface of the iodine-based polarizing element of the polarizing plate A obtained in Production Example 1 via an acrylic pressure-sensitive adhesive layer (thickness: 23 μm). : 47%) were laminated to obtain a laminate having a structure of a protective layer / iodine-based polarizing element / reflective polarizer. At this time, the reflection axis of the reflective polarizer and the absorption axis of the iodine-based polarizer were laminated so as to be parallel to each other. A TAC film (manufactured by Fujifilm Co., Ltd.) is used as a protective layer on the surface of the reflective polarizing element of the obtained laminate via the red adhesive sheet (thickness: 50 μm, single transmittance: 19.3%) obtained in Production Example 6. , Product name "TG60UL", thickness: 60 μm), and has the configuration of [red adhesive layer / reflective polarizing plate (light transmitting reflector) / iodine-based polarizing element (second polarizing element)]. An optical laminate C1 was obtained.

[Comparative Example 2]
The optical laminate C2 was the same as in Comparative Example 1 except that the blue adhesive sheet (thickness: 50 μm, single transmittance: 24.2%) obtained in Production Example 7 was used instead of the red adhesive sheet. Got

[Comparative Example 3]
The optical laminate C3 was the same as in Comparative Example 1 except that the yellow adhesive sheet (thickness: 50 μm, single transmittance: 57.9%) obtained in Production Example 8 was used instead of the red adhesive sheet. Got

[Comparative Example 4]
The optical laminate C4 was the same as in Comparative Example 1 except that the green adhesive sheet (thickness: 50 μm, single transmittance: 43.3%) obtained in Production Example 9 was used instead of the red adhesive sheet. Got

[Comparative Example 5]
An optical laminate C5 was obtained in the same manner as in Comparative Example 1 except that a TAC film with a light diffusion layer was attached to the surface of the red pressure-sensitive adhesive sheet.

[Comparative Example 6]
An optical laminate C6 was obtained in the same manner as in Comparative Example 2 except that a TAC film with a light diffusion layer was attached to the surface of the blue pressure-sensitive adhesive sheet.

[Comparative Example 7]
An optical laminate C7 was obtained in the same manner as in Comparative Example 3 except that a TAC film with a light diffusion layer was attached to the surface of the yellow adhesive sheet.

[Comparative Example 8]
An optical laminate C8 was obtained in the same manner as in Comparative Example 4 except that a TAC film with a light diffusion layer was attached to the surface of the green adhesive sheet.

[Comparative Example 9]
Reflective polarizer (manufactured by Nitto Denko Co., Ltd., product name "APCF", single transmittance: 47%) were laminated to obtain a laminate having a structure of a protective layer / iodine-based polarizing element / reflective polarizer. At this time, the reflection axis of the reflective polarizer and the absorption axis of the iodine-based polarizer were laminated so as to be parallel to each other. The polarizing plate obtained in Production Example 1 was attached to the surface of the reflective polarizer of the obtained laminate via an acrylic pressure-sensitive adhesive layer (thickness: 23 μm) so that the protective layer was on the reflective polarizer side. I matched it. At this time, the reflection axis of the reflective polarizer and the absorption axis of the iodine-based polarizer were laminated so as to be parallel to each other. A TAC film (manufactured by FUJIFILM Corporation, product name "TG60UL", thickness: 60 μm) is attached as a protective layer on the surface of the iodine-based polarizer of the obtained laminate via an acrylic adhesive layer (thickness: 23 μm). Together, an optical laminate C9 was obtained.

[Comparative Example 10]
A TAC film is used as a protective layer on the surface of the iodine-based polarizing element of the polarizing plate obtained in Production Example 1 via the red pressure-sensitive adhesive sheet (thickness: 50 μm, single transmittance: 19.3%) obtained in Production Example 2. (Manufactured by FUJIFILM Corporation, product name "TG60UL", thickness: 60 μm) were laminated to obtain an optical laminate C10.

[Comparative Example 11]
The optical laminate C11 was the same as in Comparative Example 10 except that the blue adhesive sheet (thickness: 50 μm, single transmittance: 24.2%) obtained in Production Example 3 was used instead of the red adhesive sheet. Got

[Comparative Example 12]
The optical laminate C12 was the same as in Comparative Example 10 except that the yellow adhesive sheet (thickness: 50 μm, single transmittance: 57.9%) obtained in Production Example 4 was used instead of the red adhesive sheet. Got

[Comparative Example 13]
The optical laminate C13 was the same as in Comparative Example 10 except that the green adhesive sheet (thickness: 50 μm, single transmittance: 43.3%) obtained in Production Example 5 was used instead of the red adhesive sheet. Got

Table 1 shows the configurations and optical characteristics of the optical laminates obtained in Examples and Comparative Examples.

As shown in Table 1, the optical laminate of the example has a metric saturation of 2 or more for the reflected light and more than 1.36 times the metric saturation of the transmitted light. According to an image display device using such an optical laminate, it is possible to display an image having a desired design by utilizing reflected light when not displayed, and to display an image in which coloring is suppressed at the time of display.

The optical laminate and the image display device of the present invention can be suitably used, for example, as a display unit for electric appliances such as rice cookers, refrigerators, and microwave ovens, and as a display unit for car navigation systems and instruments in a vehicle interior space.

10 First Polarizer 20 Light Transmissive Reflector 30 Second Polarizer 100 Optical Laminate

Claims (7)

An optical laminate having polarization characteristics in which the metric saturation of reflected light in the SCI method is 2 or more and exceeds 1.36 times the metric saturation of transmitted light. The optical laminate according to claim 1, wherein the difference between the metric saturation of the reflected light and the metric saturation of the transmitted light is 5 or more. It has a first polarizer containing a first dichroic substance, a light transmitting reflector, and a second polarizing element containing a second dichroic substance in this order.
The simple substance transmittance of the second polarizer is 40% or more, the degree of polarization is 97.0% or more, and the degree of polarization is 97.0% or more.
The optical laminate according to claim 1 or 2, wherein the absorption axis direction of the first polarizer and the absorption axis direction of the second polarizer are arranged so as to be substantially parallel to each other. The optical laminate according to claim 3, wherein the light-transmitting reflector has a single transmittance of 10% to 70%. The optical laminate according to claim 3 or 4, wherein the light-transmitting reflector includes a reflective polarizing element. The direction of the reflection axis of the reflective polarizer and the direction of the absorption axis of the first polarizer are substantially parallel and
The optical laminate according to claim 5, wherein the reflection axis direction of the reflective polarizer and the absorption axis direction of the second polarizer are arranged so as to be substantially parallel to each other. An image display device comprising the optical laminate according to any one of claims 1 to 6.

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