Optical laminate and image display device

Abstract

[The technical problem to be solved] The present invention provides an optical stack and an image display device comprising the optical stack. The optical stack can be used as a circular polarizer. When applied to an image display device, it ensures a sufficiently low reflectivity, and the slight leakage of internal reflected light caused by a slight deflection of the reflected hue in the in-plane of the circular polarizer is difficult to perceive. Technical means to solve the problem The present invention provides an optical stack and an image display device comprising the optical stack, wherein the optical stack sequentially comprises an optical functional layer (A), a linear polarizer and a phase difference layer having inverse wavelength dispersion, wherein the ratio of the reflectance R(450) of the optical functional layer (A) at a wavelength of 450 nm to the reflectance R(550) at a wavelength of 550 nm is 1.07 or more and 1.55 or less, and the reflectance R(550) is less than 6.0%.

Description

[Technical Field]

[0001] This invention relates to optical laminates and image display devices. [Previous Technology]

[0002] In image display devices, such as organic electroluminescent display devices, in order to suppress the reduction in visibility caused by the reflection of external light, it is known to use circular polarizers or the like to improve anti-reflection performance [for example, Japanese Patent Application Publication No. 2020-134934 (Patent Document 1)]. The circular polarizer is an optical laminate comprising a linear polarizer and a phasor layer.

[0002] [Previous Technical Documents]

[0002] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-134934

[0004] Circular polarizers are generally disposed on the viewing side of image display elements such as organic electroluminescent display elements. By disposing the circular polarizer in this way, external light incident on the image display element can be suppressed by the reflection of internal electrodes or the like within the element, thus suppressing internally reflected light emitted to the outside. In particular, it is known that if the circular polarizer is composed of a λ / 4 layer having reverse wavelength dispersion, then because the internally reflected light is suppressed over a wider visible range, it is easy to achieve black display (making the reflected hue of the circular polarizer neutral).

[0005] However, the more neutral the reflected hue of the circular polarizer becomes, the more likely it is that a small amount of internal reflected light leakage (hereinafter also referred to as "small light leakage") caused by a slight deflection of the reflected hue within the surface of the circular polarizer will be perceived as unevenness and easily recognized.

[0006] The object of the present invention is to provide an optical laminate that can be used as a circular polarizer, which, when applied to an image display device, ensures a sufficiently low reflectivity and makes the aforementioned slight light leakage difficult to perceive. Another object of the present invention is to provide an image display device incorporating the optical laminate.

[0007] The present invention provides the following optical laminate and image display device.

[0007] [1] An optical stack comprises, in sequence, an optical functional layer (A), a linear polarizer, and a phase difference layer with inverse wavelength dispersion, wherein...

[0007] The ratio of the reflectance R(450) of the aforementioned optical functional layer (A) at a wavelength of 450 nm to the reflectance R(550) at a wavelength of 550 nm is: R(450) / R(550) is more than 1.07 and less than 1.55.

[0007] The aforementioned reflectance R(550) is less than 6.0%.

[0007] [2] The optical stack as described in [1], wherein the aforementioned optical functional layer (A) is a high refractive index layer containing a refractive index of 1.6 or higher at a wavelength of 550 nm.

[0007] [3] The optical stack as described in [2], wherein the aforementioned optical functional layer (A) comprises a substrate film and the aforementioned high refractive index layer stacked thereon.

[0007] [4] An optical laminate as described in any one of [1] to [3], wherein the ratio of the aforementioned reflectivity R(450) to the aforementioned reflectivity R(550) is 1.07 or more and 1.35 or less.

[0007] [5] An optical stack as described in any one of [1] to [4], wherein the aforementioned phase difference layer comprises one or more liquid crystal curing layers.

[0007] [6] An optical laminate as described in any one of [1] to [5], wherein the aforementioned optical functional layer (A) further comprises a front panel.

[0007] [7] The optical stack as described in any one of [1] to [6] further comprises an adhesive (pressure-sensitive adhesive (PSA) layer disposed on the side opposite to the linear polarizer of the aforementioned phase difference layer.

[0007] [8] The optical stack as described in [7] further includes a separation membrane disposed on the side opposite to the phase difference layer of the aforementioned adhesive layer.

[0007] [9] The optical laminate as described in any one of [1] to [8] further has a protective film on the side of the aforementioned optical functional layer (A) opposite to the aforementioned linear polarizer.

[0007]

[10] An image display device comprising the optical stack described in any one of [1] to [9].

[0008] The present invention provides an optical stack that can be used as a circular polarizer, and an image display device containing the optical stack. When the optical stack is applied to the image display device, it ensures a sufficiently low reflectivity and the aforementioned slight light leakage is difficult to perceive. [Simplified Explanation of the Diagram]

[0009] FIG1 is a schematic cross-sectional view showing an example of an optical laminate according to the present invention.

[0009] FIG2 is a schematic cross-sectional view showing another example of an optical laminate according to the present invention.

[0009] Figure 3 is a schematic cross-sectional view showing another example of an optical laminate according to the present invention.

[0009] Figure 4 is a schematic cross-sectional view showing another example of an optical laminate according to the present invention.

[0009] Figure 5 is a schematic cross-sectional view showing another example of an optical laminate according to the present invention.

[0009] FIG6 is a schematic cross-sectional view showing an example of an image display device according to the present invention.

Implementation Method

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. All the following drawings are provided to aid in understanding the present invention, and the dimensions or shapes of the constituent elements shown in the drawings are not necessarily consistent with the actual dimensions or shapes of the constituent elements.

[0011] <Optical laminates>

[0011] The optical stack according to the present invention (hereinafter also referred to as "optical stack") can be used as a circular polarizer and sequentially includes an optical functional layer (A), a linear polarizer and a phase difference layer having reverse wavelength dispersion. The term "circular polarizer" includes an elliptical polarizer.

[0012] FIG1 is a schematic cross-sectional view showing an example of an optical stack according to the present invention. The optical stack system shown in FIG1 includes an optical functional layer (A)1, a linear polarizer 2, and a phase retardation layer 3 having reverse wavelength dispersion. The optical functional layer (A)1 and the linear polarizer 2 can be stacked with a first bonding layer 10 in between. The linear polarizer 2 and the phase retardation layer 3 can be stacked with a second bonding layer 20 in between. When the optical stack is applied to an image display device (organic EL display device, etc.), it is disposed on the viewing side of the image display element such that the optical functional layer (A)1 side of the optical stack is the viewing side, that is, the phase retardation layer 3 side is the image display element (organic electroluminescent display element, etc.) side.

[0012] The following details the constituent elements contained in or that may be contained in the optical laminate.

[0013] (1) Optical functional layer (A)

[0013] The optical functional layer (A) is a layer disposed on the viewing side of the linear polarizer 2 and has the following reflective properties.

[0013] 〔a〕The ratio of reflectance R(450) at a wavelength of 450 nm to reflectance R(550) at a wavelength of 550 nm (reflectance R(450) / reflectance R(550). Hereinafter referred to simply as "reflectance ratio") is 1.07 or more and 1.55 or less.

[0013] 〔b〕Reflectivity R(550) did not reach 6.0%.

[0013] The optical functional layer (A) generally has a laminated structure. When the reflectivity of the first bonding layer 10 is a meaningful value, the laminated structure consisting of the optical functional layer (A) 1 and the first bonding layer 10, that is, the laminated structure consisting of all the layers disposed on the viewing side of the linear polarizer 2, conforms to "optical functional layer (A)". On the other hand, when the reflectivity of the first bonding layer 10 is not a meaningful value, that is, when the reflective properties of the optical functional layer (A) 1 and the reflective properties of the above-mentioned laminated structure are substantially equal, the optical functional layer (A) 1 can be regarded as the optical functional layer (A).

[0014] By providing an optical functional layer (A)1 having the aforementioned reflective properties on the viewing side of the linear polarizer 2, the reflected light reflected from the viewing side surface of the optical stack can be made to have a blue tint, thus making the aforementioned slight light leakage difficult to see. Since the optical stack according to the present invention has a phase difference layer with inverse wavelength dispersion, and thus internal reflection is greatly suppressed, the method of the present invention, which controls the reflected light reflected from the viewing side surface of the optical stack by providing the optical functional layer (A)1, is effective in making slight light leakage difficult to see. On the other hand, even if the optical functional layer (A)1 is disposed on the viewing side of the linear polarizer 2, the transmitted light (white display) from the image display element can be suppressed from changing to a blue tint.

[0015] By adjusting the phase difference properties of the phase difference layer having a circular polarizer, the reflected hue of the circular polarizer may also have a blue color. For example, it can become a blue color by increasing the wavelength dispersion α. ​​However, in this case, other problems occur, such as the change in reflected hue from the tilt becoming larger. By providing an optical functional layer (A)1 having the above-mentioned reflective properties on the viewing side of the linear polarizer 2, such problems do not occur, and a small amount of light leakage becomes difficult to see.

[0015] In addition, wavelength dispersion α refers to the ratio of the in-plane phase difference Re(450) at a wavelength of 450 nm to the in-plane phase difference Re(550) at a wavelength of 550 nm.

[0015] Wavelength dispersion α = In-plane phase difference Re(45°) / In-plane phase difference Re(55°)

[0016] Furthermore, according to the optical laminate of the present invention, since the reflected hue of the optical laminate can be changed to a color with a moderate blue tint, a high-end feel can be provided for the display of the image display device. The degree of blue in the reflected hue can be controlled by adjusting the reflectivity R (450), reflectivity R (550), and / or the reflectivity ratio within the above-mentioned range.

[0017] From the viewpoint of making slight light leakage difficult to see and / or from the viewpoint of moderately reducing the reflectance Y of the optical laminate, the reflectance ratio is preferably 1.07 to 1.45, more preferably 1.07 to 1.35, even more preferably 1.10 to 1.35, and even more preferably 1.12 to 1.35. If the reflectance ratio exceeds 1.55, there is a tendency for the blue hue of the reflected color of the optical laminate to become too strong. If the reflectance ratio is less than 1.07, the effect of making slight light leakage difficult to see cannot be obtained.

[0018] From the viewpoint of appropriately reducing the reflectivity Y of the optical laminate, the reflectivity R (550) is preferably 5.8% or less, more preferably 5.6% or less, and even more preferably 5.4% or less. If the reflectivity R (550) is 6.0% or more, the reflectivity Y of the optical laminate becomes excessively large, and there is a tendency for the visibility of the image display device to decrease. The reflectivity R (550) can be 0.0%, generally greater than 0.0%, for example 0.1% or more, preferably 1.0% or more, more preferably 4.0% or more, and even more preferably 4.2% or more.

[0019] From the viewpoint of making a small amount of light leakage difficult to see and / or from the viewpoint of making the reflectivity Y of the optical laminate moderately smaller, the reflectivity R (450) is preferably 4.0% or more and 10.0% or less, more preferably 4.5% or more and 9.0% or less, and even more preferably 5.0% or more and 8.0% or less.

[0020] From the viewpoint of the visibility of the image display device, the reflectance Y of the optical laminate is preferably less than 6.0%, more preferably less than 5.9%, more preferably less than 5.8%, and even more preferably less than 5.7%. The reflectance Y is generally 4.0% or more.

[0021] The reflectance R(450) and reflectance R(550) of the optical functional layer (A) and the reflectance Y of the optical laminate can be determined according to the method described in the items of the [Examples] below.

[0022] The optical functional layer (A) 1 may include, for example, a high refractive index layer, a pigmented layer (e.g., a yellow pigmented layer), an alternating multilayer of high and low refractive index layers, a liquid crystal layer, a fluorescent luminescent layer, and combinations thereof. The high refractive index layer achieves the aforementioned reflective properties by utilizing interface reflection. The pigmented layer may contain, for example, a pigment that absorbs yellow light or a blue layer that enhances reflected light. The alternating multilayer of high and low refractive index layers achieves the aforementioned reflective properties by utilizing interface reflection at the interface between the high and low refractive index layers. The liquid crystal layer achieves the aforementioned reflective properties by utilizing, for example, the reflection of circularly polarized light caused by cholesteric liquid crystal. Among these, from the viewpoints of ease of operation and manufacturing in realizing the optical functional layer (A) with the aforementioned reflective properties, ease of operation in adjusting the reflected hue of the optical laminate, and the preference for uncolored transmitted light from the image display element, it is preferable that the optical functional layer (A) 1 contains a high refractive index layer.

[0023] The high refractive index layer may use conventionally known components, preferably a layer in which the refractive index imparting agent is dispersed in the binder resin. Examples of refractive index imparting agents include particles composed of metal oxides such as zirconium oxide, titanium oxide, tin oxide, zinc oxide, indium tin oxide, indium oxide, aluminum oxide, silicon oxide, yttrium oxide, and antimony oxide. The average particle size is, for example, 0.01 nm to 100 nm, preferably 0.1 nm to 50 nm.

[0024] From the viewpoint of the refractive index of the high-refractive-index layer and the ease of film formation of this layer, in 100% by mass of the high-refractive-index layer, the content of the refractive index imparting agent in the high-refractive-index layer is preferably 10% by mass or more and 90% by mass, more preferably 20% by mass or more and 80% by mass, even more preferably 30% by mass or more and 70% by mass, and even more preferably 40% by mass or more and 60% by mass. The refractive index of the high-refractive-index layer can be adjusted by the content of the refractive index imparting agent in the high-refractive-index layer. The higher the content of the refractive index imparting agent in the high-refractive-index layer, the higher the refractive index of the high-refractive-index layer can be.

[0025] The binder resin may be a thermoplastic resin or a cured product of a curable resin. The high refractive index layer may have hard film properties. In this case, the high refractive index layer may be formed from a cured product of a hard coating forming composition comprising an active energy ray-curable resin such as an ultraviolet-curable resin and a refractive index imparting agent. Examples of active energy ray-curable resins include (meth)acrylic resins, silicone resins, polyester resins, amine ester resins, amide resins, epoxy resins, etc., preferably ultraviolet-curable resins. The ultraviolet-curable resin constituting the binder resin is preferably a (meth)acrylic resin, and from the viewpoint of curability, it is more preferably a (meth)acrylic resin comprising units derived from multifunctional (meth)acrylic monomers.

[0025] Furthermore, "(meth)acrylic acid" in this specification means either acrylic acid or methacrylic acid. "(meth)" in (meth)acrylates, etc., has the same meaning.

[0026] From the perspective of the refractive index of the high refractive index layer and from the perspective of making a small amount of light leakage difficult to see, the thickness (optical film thickness) of the high refractive index layer is preferably 10 nm to 1000 nm, more preferably 10 nm to 500 nm, even more preferably 20 nm to 300 nm, even more preferably 40 nm to 250 nm, and particularly preferably 100 nm to 200 nm.

[0027] From the viewpoint of making slight light leakage difficult to see, the high refractive index layer preferably has a refractive index of 1.6 or higher at a wavelength of 550 nm, more preferably 1.62 or higher. From the viewpoint of making the reflected hue of the optical laminate a moderate blue, the refractive index is preferably 1.75 or lower, more preferably 1.70 or lower.

[0028] The optical functional layer (A)1 is generally directly deposited on the surface of the linear polarizer 2. For example, a high refractive index layer forming composition can be coated on the surface of the linear polarizer 2, and the high refractive index layer can be directly deposited on the surface of the linear polarizer 2 by drying and / or hardening as needed.

[0029] The optical functional layer (A) may be a substrate film and a high refractive index layer deposited thereon. In this case, the optical functional layer (A) 1 is deposited on the linear polarizer 2 with its substrate film side facing the linear polarizer 2, for example, with the first bonding layer 10 in between. A high refractive index layer forming composition may be coated on the substrate film, and the optical functional layer (A) comprising the substrate film and the high refractive index layer may be formed by drying and / or curing as needed. Alternatively, a linear polarizer may be fabricated by depositing the aforementioned substrate film on the viewing side of the linear polarizer 2 as a protective film for the linear polarizer 2. Furthermore, an optical laminate may be fabricated by bonding the layer constituting the optical functional layer (A) 1 other than the substrate film and the linear polarizer. In this case, the optical functional layer (A) 1 has the layer constituting the optical functional layer (A) 1 other than the substrate film and the substrate film.

[0030] The substrate film may be a thermoplastic resin film as described later. From the viewpoint of thinning, the thickness of the substrate film is generally less than 100 μm, preferably less than 80 μm, more preferably less than 60 μm, even more preferably less than 40 μm, and even more preferably less than 30 μm. In addition, it is generally more than 5 μm, and preferably more than 10 μm.

[0031] Among them, the substrate film is preferably a cyclic polyolefin resin film, a cellulose ester resin film, a polyester resin film or a (meth)acrylic resin film.

[0032] The optical functional layer (A)1 may include a thermoplastic resin film other than the substrate film. For example, a linear polarizing plate can be manufactured by laminating the thermoplastic resin film on the viewing side of the linear polarizer 2 as a protective film for the linear polarizer 2. Furthermore, an optical laminate can be manufactured by bonding the layer constituting the optical functional layer (A)1 other than the thermoplastic resin film to the linear polarizer. In this case, the optical functional layer (A)1 may have a layer constituting the optical functional layer (A)1 other than the thermoplastic resin film and a thermoplastic resin film. Details regarding the thermoplastic resin film will be described later.

[0033] When the optical functional layer (A) includes a high refractive index layer and a substrate film, from the viewpoint that a small amount of light leakage is difficult to see, the refractive index difference at a wavelength of 550 nm is preferably 0.05 or more and 0.30 or less, more preferably 0.08 or more and 0.26 or less, and even more preferably 0.10 or more and 0.24 or less.

[0034] When the optical functional layer (A) comprises a high refractive index layer and a substrate film, the resin layer may be intervening between the high refractive index layer and the substrate film, or the resin layer may be disposed on the side of the high refractive index layer opposite to the substrate film. An example of a resin layer is a hard coating layer. Alternatively, the resin layer that may be intervening between the high refractive index layer and the substrate film may be a primer layer. The description of hard coating layers is cited below.

[0035] When the optical functional layer (A) includes a substrate film and a resin layer, a linear polarizing plate is manufactured by depositing the substrate film and the resin layer on the viewing side of the linear polarizer 2, each serving as a protective film and a hard coating layer of the linear polarizer 2. Furthermore, an optical laminate can be manufactured by bonding the layer constituting the optical functional layer (A) 1 other than the substrate film and the resin layer to the linear polarizer. In this case, the optical functional layer (A) 1 has the layer constituting the optical functional layer (A) 1 other than the substrate film and the resin layer, the substrate film, and the resin layer.

[0036] When the above-mentioned resin layer is included, from the viewpoint that a small amount of light leakage is difficult to see, the refractive index difference between the resin layer and the high refractive index layer at a wavelength of 550 nm is preferably 0.05 or more and 0.30 or less, more preferably 0.08 or more and 0.26 or less, and even more preferably 0.10 or more and 0.24 or less.

[0037] The optical functional layer (A)1 may comprise one or more high-refractive-index layers, pigment-containing layers (e.g., yellow pigment-containing layers), alternating layers of high-refractive-index and low-refractive-index layers, liquid crystal layers, fluorescent light-emitting layers, or combinations thereof, layers that adjust the reflective properties (reflectivity Y, reflected hue) of the optical laminate. Such layers may include, for example, the resin layer described above. The resin layer may be disposed between the high-refractive-index layer and the substrate film, or on the opposite side of the substrate film within the high-refractive-index layer. The resin layer may be an adhesive layer.

[0037] Other examples of a layer whose reflective properties can be adjusted include: a front panel 90, which is disposed on the side of the high refractive index layer opposite to the substrate film, separated by an adhesive layer (the sixth bonding layer 80 described later). Another example of a layer whose reflective properties can be adjusted includes thermoplastic resin films other than the substrate film mentioned above.

[0038] The optical functional layer (A)1 is preferably one with high electrical insulation, for example, a layer with a resistivity exceeding 1.0 × 10⁷ Ω / □. Furthermore, in order to improve electrical insulation, an optical functional layer without a mesh structure such as a metal mesh layer, that is, an optical functional layer that is uniformly distributed throughout, is preferred.

[0039] (2) Linear polarizer

[0039] The linear polarizer 2 has the function of selectively allowing linearly polarized light in a certain direction to pass through unpolarized light such as natural light. Examples of linear polarizers include, for example, an extended film or extended layer with adsorbed dichroic pigments, a cured material containing polymeric liquid crystal compounds and a liquid crystal cured layer containing dichroic pigments, etc. The optical functional layer (A) 1 and the linear polarizer 2 can be laminated with the first bonding layer 10 in between.

[0040] A linear polarizer with an extended film adsorbed with dichroic pigments can generally be manufactured by the following steps: uniaxial stretching of a polyvinyl alcohol resin film, dyeing the polyvinyl alcohol resin film with dichroic pigments such as iodine to adsorb the dichroic pigments, treating the polyvinyl alcohol resin film adsorbed with a boric acid aqueous solution, and washing with water after treatment with a boric acid aqueous solution.

[0041] The thickness of the extended film adsorbed with dichroic pigment is generally 30 μm or less, preferably 18 μm or less, and even more preferably 15 μm or less. The thickness is generally 1 μm or more, for example, 5 μm or more.

[0042] Polyvinyl alcohol resins can be obtained by saponifying polyvinyl acetate resins. Besides polyvinyl acetate as a homopolymer of vinyl acetate, polyvinyl acetate resins can, for example, be copolymers of vinyl acetate and other monomers that can be copolymerized with it. Other monomers that can be copolymerized with vinyl acetate include, for example, unsaturated carboxylic acid compounds, olefin compounds, vinyl ether compounds, unsaturated urethane compounds, and (meth)acrylamide compounds having an ammonium group.

[0043] The degree of saponification of polyvinyl alcohol (PVA) resins is generally between 85 mol% and 100 mol%, preferably above 98 mol%. PVA resins can be modified, and aldehyde-modified polyvinyl formaldehyde, polyvinyl acetal, etc., can also be used. The degree of polymerization of PVA resins is generally between 1000 and 10000, preferably between 1500 and 5000.

[0044] A linear polarizer with an extended layer adsorbed with dichroic pigment can generally be manufactured through the following steps: applying a coating solution containing the above-mentioned polyvinyl alcohol resin onto a substrate layer; uniaxially stretching to obtain a laminated film; dyeing the polyvinyl alcohol resin layer of the uniaxially stretched laminated film with dichroic pigment to adsorb the dichroic pigment; treating the film adsorbed with dichroic pigment with a boric acid aqueous solution; and washing with water after treatment with a boric acid aqueous solution. The substrate layer can be used as a protective film for the linear polarizer or can be peeled off from the linear polarizer. The material and thickness of the substrate layer can be the same as the material and thickness of the thermoplastic resin film described later.

[0045] The optical laminate may include a protective film laminated on one or both sides of a linear polarizer on which an extended film or extended layer of dichroic pigment is adsorbed. The protective film may be a thermoplastic resin film described later. The linear polarizer and the protective film may be laminated in place of an adhesive layer described later.

[0045] As described above, the thermoplastic resin film (protective film) deposited on the viewing side of the linear polarizer may be included in the optical functional layer (A). The thermoplastic resin film and the linear polarizer may be bonded together through the first bonding layer.

[0046] Thermoplastic resins constituting thermoplastic resin films can include, for example: cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyether resins; polyether resins; polycarbonate resins; polyamide resins such as nylon or aromatic polyamides; polyimide resins; polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin resins and cyclic polyolefin resins with a nobornene structure (also known as nobornene resins); (meth)acrylic resins; polyarylate resins; polystyrene resins; polyvinyl alcohol resins, etc. Among these, cyclic polyolefin resin films, cellulose ester resin films, polyester resin films, or (meth)acrylic resin films are preferred.

[0047] From the perspective of thinning, the thickness of thermoplastic resin film is generally less than 100μm, preferably less than 80μm, more preferably less than 60μm, even more preferably less than 40μm, and even more preferably less than 30μm. Also, it is usually more than 5μm, and preferably more than 10μm.

[0048] The hard coating can be formed on the thermoplastic resin film. The hard coating can be formed on one side of the thermoplastic resin film or on both sides. By providing the hard coating, a thermoplastic resin film with improved hardness and scratch resistance can be obtained.

[0049] The hard coating is, for example, a resin that can be cured by active energy radiation, preferably a resin that can be cured by ultraviolet light. Examples of ultraviolet-curable resins include (meth)acrylic resins, silicone resins, polyester resins, amine resins, amide resins, epoxy resins, etc. To improve strength, the hard coating may contain additives. Additives are not particularly limited and may include inorganic microparticles, organic microparticles, or mixtures thereof.

[0050] The polymerizable liquid crystal compound used to form a linear polarizer belonging to the liquid crystal curing layer has polymerizable reactive groups and is a compound exhibiting liquid crystal properties. The polymerizable reactive group is a group that participates in the polymerization reaction, preferably a photopolymerizable reactive group. A photopolymerizable reactive group refers to a group that can participate in the polymerization reaction due to active free radicals or acids generated from a photopolymerization initiator. Examples of photopolymerizable reactive groups include: vinyl, methacryloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, ethylene oxide (oxiranyl group), oxetanyl (oxetanyl group), etc. Among these, acryloxy, methacryloxy, methacryloxy, ethylene oxide, and oxetanyl are preferred, with acryloxy being more preferred. The type of polymerizable liquid crystal compound is not particularly limited; rod-shaped liquid crystal compounds, disc-shaped liquid crystal compounds, and mixtures thereof can be used. The liquid crystal properties of polymeric liquid crystal compounds can be thermotropic or lyotropic. If thermotropic liquid crystals are classified according to their degree of order, they can be nematic liquid crystals or smectic liquid crystals.

[0051] In the liquid crystal curing layer, the dichroic pigment is dispersed and aligned in the cured polymeric liquid crystal compound. The dichroic pigment used in the linear polarizer of the liquid crystal curing layer preferably has a wavelength with maximum absorption in the range of 300 nm to 700 nm. Examples of such dichroic pigments include acridine pigments, pigments, anthocyanin, naphthalene pigments, azo dyes, and anthraquinone pigments, among which azo dyes are preferred. Examples of azo dyes include monoazo dyes, diazo dyes, triazo dyes, tetraazo dyes, and stilbene azo dyes, with diazo dyes and triazo dyes being preferred. The dichroic pigment can be used alone or in combination of two or more, with combination of three or more being preferred. In particular, combination of three or more azo compounds is preferred. A portion of the dichroic pigment may have a reactive group or may have liquid crystal properties.

[0052] A linear polarizer belonging to the liquid crystal curing layer can be formed, for example, by coating an alignment film formed on a substrate layer with a linear polarizer forming composition containing a polymeric liquid crystal compound and a dichroic pigment, and then polymerizing and curing the polymeric liquid crystal compound. Alternatively, a linear polarizer forming composition can be formed by coating a substrate layer with a linear polarizer forming composition, and by simultaneously extending this coating film and the substrate layer, a linear polarizer is formed. The substrate layer used to form the linear polarizer can be a protective film for the linear polarizer. The material and thickness of the substrate layer can be the same as the material and thickness of the thermoplastic resin film described above.

[0053] Examples of linear polarizer forming compositions containing polymerizable liquid crystal compounds and dichroic pigments, and methods for manufacturing linear polarizers using the same compositions, include those described in Japanese Patent Application Publication Nos. 2013-37353, 2013-33249, and 2017-83843. In addition to polymerizable liquid crystal compounds and dichroic pigments, the linear polarizer forming compositions may further include additives such as solvents, polymerization initiators, crosslinking agents, leveling agents, antioxidants, plasticizers, and sensitizers. Only one of these components may be used, or two or more may be used in combination.

[0054] The polymerization initiator that may contain the composition for forming a linear polarizer is a compound capable of initiating the polymerization reaction of a polymerizable liquid crystal compound. From the viewpoint that the polymerization reaction can be initiated at lower temperature conditions, a photopolymerizable initiator is preferred. Specifically, photopolymerizable initiators that can generate active free radicals or acids by the action of light can be listed, among which photopolymerizable initiators that generate free radicals by the action of light are preferred. The content of the polymerization initiator is preferably 1 part by mass to 10 parts by mass relative to 100 parts by mass of the total amount of the polymerizable liquid crystal compound, and more preferably 3 parts by mass to 8 parts by mass. If it is within this range, the reaction of the polymerizable radicals will proceed sufficiently, and the alignment state of the liquid crystal compound will be easily stabilized.

[0055] The thickness of the linear polarizer belonging to the liquid crystal curing layer is generally less than 10 μm, preferably more than 0.5 μm and less than 8 μm, and even more preferably more than 1 μm and less than 5 μm.

[0056] The optical stack may include the aforementioned substrate layer on which a linear polarizer belonging to the liquid crystal curing layer is formed. This substrate layer may be the aforementioned thermoplastic resin film contained in the optical functional layer (A) or a protective film for the linear polarizer. Alternatively, the substrate layer may be peeled off from the linear polarizer. The optical stack may or may not have the aforementioned alignment film.

[0057] For purposes such as protecting linear polarizers, linear polarizers belonging to liquid crystal curing layers may have an outer coating layer on one or both sides. The outer coating layer may be formed, for example, by coating the linear polarizer with a composition for forming the outer coating layer. Materials constituting the outer coating layer may include, for example, photocurable resins, water-soluble polymers, etc. Specifically, (meth)acrylic resins, polyvinyl alcohol resins, etc., may be used.

[0058] The visual sensitivity correction polarization Py of a linear polarizer is generally above 95%, preferably above 97%, even better above 98%, and still better above 98.7%, even better above 99.0%, and exceptionally good above 99.4%, and can also be above 99.9%. The visual sensitivity correction polarization Py of a linear polarizer can also be below 99.999% or below 99.99%.

[0058] The visual sensitivity correction polarization Py can be calculated by performing visual sensitivity correction on the obtained polarization using a spectrophotometer equipped with an integrating sphere ("V7100" manufactured by Japan Spectrophotometer Co., Ltd.) with a 2-degree field of view (C light source) of "JIS Z 8701".

[0059] Increasing the visual sensitivity correction polarization Py of the linear polarizer is beneficial for improving the anti-reflection function of the optical laminate. If the visual sensitivity correction polarization Py is less than 95%, the anti-reflection function may not be able to be performed.

[0060] The transmittance Ty of a linear polarizer's optical sensitivity correction unit is generally above 41%, preferably above 41.1%, more preferably above 41.2%, and can also be above 42% or above, or above 42.5%. The transmittance Ty of a linear polarizer's optical sensitivity correction unit is generally below 50%, and can also be below 48%, below 46%, below 44%, or below 43%. If the transmittance Ty of the optical sensitivity correction unit is excessively high, the optical sensitivity correction polarization Py becomes too low, resulting in insufficient anti-reflection function of the optical laminate.

[0060] The transmittance Ty of a single unit with visual sensitivity correction can be calculated by performing visual sensitivity correction on the transmittance using a spectrophotometer with an integrating sphere ("V7100" manufactured by Japan Spectrophotometer Co., Ltd.) with a 2-degree field of view (C light source) of "JIS Z 8701".

[0061] For the linear polarizer system, the orthogonal hue a* is preferably in the range of -5 to 5, and more preferably in the range of -3 to 3. Furthermore, the orthogonal hue b* is preferably in the range of -10 to 10, more preferably in the range of -5 to 5, and even more preferably in the range of -3 to 3. By using a spectrophotometer equipped with an integrating sphere ("V7100" manufactured by Japan Spectrophotometer Co., Ltd.), the chromaticity a* and b* in the L*a*b* (CIE) color system are calculated using color functions such as the C light source on the obtained transmittance. This yields the hue of a single linear polarizer (single hue), the hue of a linear polarizer arranged in parallel (parallel hue), and the hue of a linear polarizer arranged orthogonally (orthogonal hue).

[0062] (3) Phase difference layer

[0062] The optical stacking system includes a phase retardation layer 3 having a first phase retardation layer 3a. The linear polarizer 2 and the first phase retardation layer 3a can be stacked with the second bonding layer 20 in between. When the protective film is stacked on the side of the linear polarizer 2 opposite to the viewing side, the protective film and the first phase retardation layer 3a can be stacked by means of the second bonding layer 20.

[0063] The phase retardation layer 3 may consist only of the first phase retardation layer 3a, or it may be a laminated structure composed of two or more phase retardation layers. That is, the phase retardation layer 3 may include one or more other phase retardation layers different from the first phase retardation layer 3a. The phase retardation layer 3 may have an outer coating layer that protects its surface, a substrate layer that supports the phase retardation layer 3, etc.

[0064] The first phase retardation layer 3a is, for example, a λ / 4 layer. When the phase retardation layer 3 contains two phase retardation layers, the combinations of these phase retardation layers from the linear polarizer 2 side can be listed in sequence as follows: a combination of a λ / 4 layer and a positive C layer, a combination of a λ / 2 layer and a λ / 4 layer, and a combination of a positive C layer and a λ / 4 layer. A bonding layer (the fifth bonding layer), described later, can be used in the stacking of the phase retardation layers.

[0065] The in-plane phase difference Re(550) of the λ / 4 layer at a wavelength of 550 nm is generally in the range of 90 nm to 220 nm, preferably in the range of 100 nm to 200 nm. The in-plane phase difference Re(550) of the λ / 2 layer at a wavelength of 550 nm is preferably in the range of 100 nm to 300 nm, more preferably in the range of 150 nm to 300 nm, and even more preferably in the range of 200 nm to 300 nm. Furthermore, the phase difference Rth(550) of the positive C layer in the thickness direction at a wavelength of 550 nm is generally in the range of -170 nm to -10 nm, preferably in the range of -150 nm to -20 nm.

[0066] The phase difference layer 3 has reverse wavelength dispersion, wherein a wavelength dispersion α of 0.80 to 0.88 is preferred. This can effectively suppress the aforementioned internal reflection.

[0066] Wave dispersion α refers to the ratio of the in-plane phase difference Re(450) at a wavelength of 450 nm to the in-plane phase difference Re(550) at a wavelength of 550 nm.

[0066] Wavelength dispersion α = In-plane phase difference Re(45°) / In-plane phase difference Re(55°)

[0067] The first phase retardation layer 3a and other phase retardation layers may be phase retardation films formed by extending the aforementioned thermoplastic resin film, or they may be liquid crystal curing layers. The liquid crystal curing layer is a curing layer formed by polymerizing and curing a polymeric liquid crystal compound in an aligned state. The phase retardation layer 3 may contain one or more liquid crystal curing layers, or it may contain two or more layers.

[0068] Examples of polymerizable liquid crystal compounds include rod-shaped and disc-shaped polymerizable liquid crystal compounds. One of these can be used, or a mixture containing both can be used. When the rod-shaped polymerizable liquid crystal compound is horizontally or vertically aligned with the substrate layer, the optical axis of the polymerizable liquid crystal compound is aligned with its long axis. When the disc-shaped polymerizable liquid crystal compound is aligned, its optical axis exists in a direction orthogonal to the disc surface of the polymerizable liquid crystal compound.

[0069] To enable the liquid crystal curing layer formed by polymerizing the polymeric liquid crystal compound to display in-plane phase difference, the polymeric liquid crystal compound can be aligned in a suitable direction. When the polymeric liquid crystal compound is rod-shaped, the in-plane phase difference is displayed by horizontally aligning the optical axis of the polymeric liquid crystal compound relative to the plane of the substrate layer. In this case, the direction of the optical axis is consistent with the direction of the slow axis. When the polymeric liquid crystal compound is disk-shaped, the in-plane phase difference is displayed by horizontally aligning the optical axis of the polymeric liquid crystal compound relative to the plane of the substrate layer. In this case, the optical axis is orthogonal to the slow axis. The alignment state of the polymeric liquid crystal compound can be adjusted by combining the alignment layer and the polymeric liquid crystal compound.

[0070] A polymerizable liquid crystal compound is a compound having at least one polymerizable reactive group and exhibiting liquid crystal properties. When two or more types of polymerizable liquid crystal compounds are used, it is preferable that at least one type has two or more polymerizable reactive groups within its molecule. The polymerizable reactive group is preferably a group that participates in the polymerization reaction or a photopolymerizable reactive group. A photopolymerizable reactive group is a group that can participate in the polymerization reaction, formed by an active free radical generated from a photopolymerization initiator or an acid, etc. Examples of photopolymerizable reactive groups are the same as those described above. The liquid crystal properties of a polymerizable liquid crystal compound can be thermotropic or lyotropic. If classified by degree of order, thermotropic liquid crystals can be nematic liquid crystals or lamellar liquid crystals.

[0071] The optical stack may contain an alignment layer adjacent to the retardation layer. The alignment layer has an alignment regulating force that orients the polymeric liquid crystal compound in a desired direction. The alignment layer may be a vertical alignment layer that orients the molecular axis of the polymeric liquid crystal compound perpendicularly relative to the substrate layer, a horizontal alignment layer that orients the molecular axis of the polymeric liquid crystal compound horizontally relative to the substrate layer, or an inclined alignment layer that orients the molecular axis of the polymeric liquid crystal compound obliquely relative to the substrate layer.

[0072] The thickness of the liquid crystal curing layer can be 0.1μm or more, or 0.5μm or more, or 1μm or more, or 2μm or more. It is preferred to be 10μm or less, or 8μm or less, or 5μm or less.

[0073] The liquid crystal curing layer can be formed by coating a liquid crystal layer forming composition containing a polymerizable liquid crystal compound onto a substrate layer and drying it, thereby polymerizing the polymerizable liquid crystal compound. The liquid crystal layer forming composition can also be coated onto an alignment layer formed on the substrate layer. The material and thickness of the substrate layer can be the same as those of the thermoplastic resin film described above. The substrate layer can be incorporated into an optical laminate as a phase retardation layer serving as the liquid crystal curing layer, or the substrate layer can be peeled off, leaving only the liquid crystal curing layer, or the liquid crystal curing layer and the alignment layer can be incorporated into the optical laminate.

[0074] (4) Adhesive layer

[0074] FIG2 is a schematic cross-sectional view of another example of an optical laminate according to the present invention. The optical laminate system shown in FIG2 includes an optical functional layer (A)1, a first bonding layer 10, a linear polarizer 2, a second bonding layer 20, a phase difference layer 3 having inverse wavelength dispersion, and an adhesive layer 50. The adhesive layer 50 can be deposited on the side of the optical laminate opposite to the viewing side (the side of the optical functional layer (A)1), and can be used for bonding optical laminates of image display elements such as organic electroluminescent display elements.

[0075] In the optical laminate shown in FIG. 2, the optical functional layer (A) 1 is provided sequentially from the viewing side as a high refractive index layer 1a, a substrate film 1b, a third bonding layer 30, and a thermoplastic resin film 11. The protective film 12 is deposited on the opposite side of the viewing side of the linear polarizer 2, separated by a fourth bonding layer 40. The third bonding layer 30 and the thermoplastic resin film 11 may be omitted. The fourth bonding layer 40 and the protective film 12 may also be omitted.

[0075] In the optical stack shown in FIG2, the phase retardation layer 3 includes a first phase retardation layer 3a and a second phase retardation layer 3b. The first phase retardation layer 3a and the second phase retardation layer 3b are bonded together by a fifth bonding layer 3c. However, the fifth bonding layer 3c and the second phase retardation layer 3b may be omitted.

[0076] The thickness of the adhesive layer 50 may be, for example, 250 μm or less, and from the viewpoint of thinning, preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less. From the viewpoint of durability, the lower limit of the thickness of the adhesive layer may be, for example, 1 μm or more, preferably 5 μm or more, and even more preferably 10 μm or more.

[0077] The adhesive layer 50 may be composed of an adhesive composition mainly composed of (meth)acrylic resin, rubber resin, amine ester resin, ester resin, silicone resin, or polyvinyl ether resin. Among these, (meth)acrylic resin, which has excellent transparency, weather resistance, and heat resistance, is suitable as the adhesive composition of the matrix polymer. The adhesive composition may be of the active energy radiation curing type or the thermosetting type.

[0078] The (meth)acrylate resin (matrix polymer) used in the adhesive composition is suitable as a polymer or copolymer with one or more (meth)acrylate monomers such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Among the matrix polymers, those copolymerized with polar monomers are preferred. Examples of polar monomers include: (meth)acrylate, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate, which have carboxyl, hydroxyl, amide, amino, or epoxy groups.

[0079] The adhesive composition may contain only the above-mentioned matrix polymer, but generally it also contains a crosslinking agent. Examples of crosslinking agents include: metal ions with a valence of divalent or higher, metal ions that form carboxylic acid metal salts with carboxyl groups; polyamines that form amide bonds with carboxyl groups; polyepoxides or polyols that form ester bonds with carboxyl groups; and polyisocyanate compounds that form amide bonds with carboxyl groups. Polyisocyanate compounds are preferred.

[0080] The adhesive layer 50 may contain a light-selective absorber. The light-selective absorber, for example, has a maximum absorption wavelength in the wavelength range of 390 to 430 nm, which is a short wavelength band of visible light. Here, in this embodiment, "visible light" refers to light with wavelengths in the range of 390 nm to 830 nm. Examples of such light-selective absorbers include salicylate compounds, diphenyl ketone compounds, benzotriazole compounds, cyanoacrylate compounds, trihydric compounds, and nickel zirconia salt compounds.

[0080] Alternatively, compounds with extremely high absorption wavelengths in the wavelength band of 390 to 430 nm can be synthesized by known methods and used as light-selective absorbers. Such pigments can use, for example, known compounds as light-selective absorbers disclosed in Japanese Patent Application Publication No. 2017-120430.

[0081] The adhesive layer 50 may be an adhesive layer that satisfies the following formula (1).

[0081] A(410)≧0.1 (1)

[0081] [In formula (1), A(410) represents the absorbance at a wavelength of 410 nm.]

[0082] A higher value of A(410) indicates higher light absorption at a wavelength of 410 nm. If the value of A(410) is less than 0.1, the light absorption at a wavelength of 410 nm is low, and the degradation of the phase retardation layer of the organic electroluminescent display element and the liquid crystal curing layer, which uses light near 400 nm, is more likely to occur. The value of A(410) is preferably 0.3 or higher, more preferably 0.8 or higher, and especially preferably 1.0 or higher. There is no particular upper limit, and it is generally below 10.

[0083] When the adhesive layer 50 described above contains a light-selective absorber and has light-selective absorption properties, since the reflected hue is close to black (the reflected hue of the circular polarizer becomes neutral), a small amount of light leakage becomes easily visible. Therefore, it is also advantageous when the optical laminate of the present invention, which has an optical functional layer (A) that makes a small amount of light leakage difficult to see, contains a layer with light-selective absorption properties. Furthermore, not only the adhesive layer, but also the light-absorbing properties can be provided in the resin layer, hard coating layer, adhesive layer, etc. The aforementioned light-selective absorber can be included in the resin layer, hard coating layer, adhesive layer, etc.

[0084] The active energy radiation-curing adhesive composition has the property of curing upon irradiation with active energy radiation such as ultraviolet light or electron beams. It retains its adhesiveness even before irradiation and can adhere tightly to films and other adhesives. It also has the property of adjusting adhesive strength through curing by active energy radiation. Ultraviolet curing is preferred for active energy radiation-curing adhesive compositions. In addition to the matrix polymer and crosslinking agent, the active energy radiation-curing adhesive composition contains active energy radiation polymerizable compounds. Photopolymerization initiators and photosensitizers may also be included as needed.

[0085] (5) Separation membrane

[0085] As shown in FIG3, the optical laminate may include a release membrane 60 for protecting the outer surface of the adhesive layer 50 (the surface opposite to the second retardation layer 3b). The optical laminate shown in FIG3 has the same layer composition as the optical laminate shown in FIG2 except for the release membrane 60. The release membrane 60 is generally made of a thermoplastic resin film on one side that has undergone release treatment with a release agent such as a silicone-based or fluorine-based release agent, and this release-treated side is adhered to the adhesive layer 50.

[0086] The thermoplastic resin constituting the separation membrane 60 is, for example, polyethylene resin such as polyethylene, polypropylene resin such as polypropylene, polyester resin such as polyethylene terephthalate or polyethylene naphthalate, etc. The thickness of the separation membrane 60 is, for example, 10 μm or more and 50 μm or less.

[0087] (6) Protective film

[0087] As shown in FIG. 4, the optical laminate may include a protective film 70 deposited on the side of the optical functional layer (A) 1. The optical laminate shown in FIG. 4, except for the protective film 70, has the same layer structure as the optical laminate shown in FIG. 3. The protective film 70 is, for example, composed of a substrate film and an adhesive layer deposited thereon. The adhesive layer is described above. The resin constituting the substrate film may be, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, a thermoplastic resin such as polycarbonate resin, etc. Preferably, it is a polyester resin such as polyethylene terephthalate.

[0088] (7) Front panel

[0088] As shown in FIG. 5, the optical functional layer (A) 1 may further include a front panel 90. The front panel 90 is generally disposed on the outermost surface of the viewing side in the optical laminate. For example, the front panel 90 may be laminated on the viewing side surface of the high refractive index layer 1a with the sixth bonding layer 80 in between. In this case, the optical functional layer (A) 1 includes the sixth bonding layer 80 and the front panel 90. The optical laminate shown in FIG. 5 has the same layer structure as the optical laminate shown in FIG. 3, except for the sixth bonding layer 80 and the front panel 90.

[0089] If the front panel 90 is a light-transmitting plate, the material and thickness are not limited. The front panel 90 may consist of only one layer or two or more layers. Examples of materials for the front panel 90 include resin plates (e.g., resin boards, resin sheets, resin films, etc.), glass plates (e.g., glass plates, glass films, etc.), and laminates of resin plates and glass plates. The front panel may constitute the outermost surface of the display device.

[0090] The thickness of the front panel 90 is, for example, 1000 μm or less, preferably 800 μm or less. This thickness is generally 10 μm or more, preferably 20 μm or more.

[0091] Examples of resins constituting the resin-based plate-like structure include: triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, propylene cellulose, butyl cellulose, acetylpropylene cellulose, polyester, polystyrene, polyamide, polyetherimide, poly(meth)acrylic acid, polyamide, polyether ether, polyether ether, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyether ether, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyamide-amide, and other thermoplastic resins. These thermoplastic resins can be used alone or in mixtures of two or more. From the perspective of strength and transparency, the preferred resin-based plate-like material is a thermoplastic resin film formed from polyimide, polyamide, polyamide-imide, etc.

[0092] From the viewpoint of hardness, the front panel 90 may be a thermoplastic resin film with a hard coating. The hard coating may be formed on one side of the thermoplastic resin film or on both sides. By providing a hard coating, hardness and scratch resistance can be improved. Regarding the hard coating, the above description of a hard coating that can be formed on a thermoplastic resin film is cited.

[0093] When the front panel 90 is a glass plate, it is preferable to use tempered glass for displays. The thickness of the glass plate can be, for example, 10μm to 1000μm or 10μm to 800μm. By using a glass plate, a front panel with excellent mechanical strength and surface hardness can be formed.

[0094] A high rigidity is preferred for the front panel 90 series, for example, a Young's modulus of 70 GPa or higher, or even 80 GPa or higher. The Young's modulus of the front panel 90 is generally below 100 GPa. The Young's modulus can be determined as follows: A front panel 90 sample with a long side of 110 mm × a short side of 10 mm is cut using a super cutter. Next, the sample is clamped at both ends of the long side with the upper and lower clamps of a tensile testing machine (Autograph AG-Xplus testing machine manufactured by Shimadzu Corporation) with a clamping distance of 5 cm. The sample is stretched along the longer side at a temperature of 23°C and a relative humidity of 55% at a tensile speed of 4 mm / min. The Young's modulus at 23°C and a relative humidity of 55% can be calculated from the inclination of the straight line between 20 and 40 MPa in the obtained stress-strain curve.

[0095] When the optical functional layer (A)1 includes a front panel 90 on the viewing side of the high refractive index layer 1a, with the sixth adhesive layer 80 deposited therebetween, from the viewpoint of making slight light leakage difficult to see, the refractive index of the sixth adhesive layer 80 at a wavelength of 550 nm is preferably 1.45 or more and 1.51 or less, more preferably 1.46 or more and 1.50 or less, and the refractive index of the front panel 90 at a wavelength of 550 nm is preferably 1.49 or more and 1.52 or less, more preferably 1.50 or more and 1.52 or less. The sixth adhesive layer 80 is preferably an adhesive layer.

[0096] When an optical laminate is applied to an image display device, the front panel 90 not only has the function of protecting the front of the image display device (the screen, which functions as a window film), but can also have the functions of a touch sensor, blue light blocking, and viewing angle adjustment.

[0097] (8) Adhesive layer

[0097] The optical laminate may include an adhesive layer for bonding two layers (or films). Examples of adhesive layers include a first adhesive layer 10 for bonding the optical functional layer (A) 1 to the linear polarizer 2, a second adhesive layer 20 for bonding the linear polarizer 2 (or protective film 12) to the retardation layer 3, a third adhesive layer 30 for bonding the substrate film 1b to the thermoplastic resin film 11, a fourth adhesive layer 40 for bonding the linear polarizer 2 to the protective film 12, a fifth adhesive layer 3c for bonding the first retardation layer 3a to the second retardation layer 3b, and a sixth adhesive layer 80 for bonding the front panel 90.

[0098] The bonding layer is an adhesive layer composed of an adhesive composition or an adhesive layer composed of an adhesive composition. The description of the adhesive composition and the adhesive layer is cited above in (4).

[0099] Examples of adhesive compositions include aqueous adhesives and active energy radiation-cured adhesives. Examples of aqueous adhesives include aqueous solutions of polyvinyl alcohol resins and aqueous two-component amine ester emulsion adhesives. Active energy radiation-cured adhesives are adhesives that are cured by irradiation with active energy rays such as ultraviolet light, and examples include adhesives containing polymerizable compounds and photopolymerizable initiators, adhesives containing photoreactive resins, and adhesives containing adhesive resins and photoreactive crosslinking agents. Examples of polymerizable compounds include photopolymerizable monomers such as photocurable epoxy monomers, photocurable (meth)acrylate monomers, and photocurable amine ester monomers, as well as oligomers derived from these monomers. Examples of photopolymerizable initiators include compounds containing substances that generate reactive species such as neutral free radicals, anionic free radicals, and cationic free radicals when irradiated with active energy rays such as ultraviolet light.

[0100] The thickness of the adhesive layer composed of the adhesive composition may be, for example, 0.1 μm or more, preferably 0.5 μm or more, 1 μm or more or 2 μm or more, or less than 100 μm, less than 50 μm, less than 25 μm, less than 15 μm or less.

[0100] The two opposing surfaces bonded together through the bonding layer can undergo surface activation treatments such as pre-corona treatment, plasma treatment, and flame treatment.

[0101] <Image display device>

[0101] The image display device according to the present invention includes an optical laminate and an image display element (organic electroluminescent display element, etc.) according to the present invention. The optical laminate is disposed on the viewing side of the image display element. An adhesive layer 50 can be used to attach the optical laminate to the image display element.

[0102] FIG6 is a schematic cross-sectional view showing an example of an image display device according to the present invention. In FIG6, the optical laminate shown in FIG5 is used as an example of an optical laminate. The optical laminate system is attached to the image display element 100 using the adhesive layer 50. On the side of the optical laminate opposite to the adhesive layer 50 (the outermost surface of the viewing side), the front panel 90 is laminated with a sixth bonding layer 80 in between.

[0103] The image display device is not particularly limited, and examples include organic electroluminescent (organic EL) display devices, inorganic electroluminescent (inorganic EL) display devices, liquid crystal display devices, electroluminescent display devices, etc.

[0104] The image display device can be used as a smartphone, tablet and other mobile machine, television, digital photo frame, electronic signboard, measuring instrument and counter, office machine, medical machine, computer machine, etc.

[0104] [Example]

[0105] Hereinafter, embodiments and comparative examples are shown and the present invention is further described in detail, but the present invention is not limited to these examples.

[0106] [Measurement]

[0106] (1) Reflectivity of the optical functional layer

[0106] The reflectance R(450) and reflectance R(550) of the optical functional layer were measured using a "Cm2600d" manufactured by Konica Minolta. During the measurement, a black acrylic sheet ("Kanase Lite1410" manufactured by Kanase Co., Ltd.) was attached to the side of the optical functional layer opposite to the side where light is incident, through an adhesive layer.

[0107] (2) Refractive index and optical film thickness

[0107] The refractive index of the film and layer at a wavelength of 550 nm was measured as follows. The reflectance in the visible light region was measured using a Shimadzu MPC-2200 spectrophotometer. During measurement, a black acrylic plate (Kanase Lite 1410, manufactured by Kanase Co., Ltd.) was attached to the back side of the measurement surface through an adhesive layer. Regarding the obtained reflectance spectrum, the characteristics of the spectrum calculated from the formula for thin film interference spectrum were used, especially by combining the reflectance at a wavelength of 550 nm and performing spectral fitting to calculate the refractive index and optical film thickness at a wavelength of 550 nm. However, regarding the laminate B-1, the refractive index and optical film thickness of the high-refractive-index layer at a wavelength of 550 nm were measured using the following method.

[0108] (3) Phase difference properties of the phase difference layer

[0108] The phase difference properties of the phase difference layer were measured using the "KOBRA-WPR" of Oji Measurement & Testing Co., Ltd.

[0109] Hereinafter, in this embodiment and comparative example, the optical functional layers in the optical laminates obtained from laminates A-1 to A-5, B-1 and B-2 will be referred to as optical functional layers A-1' to A-5', B-1' and B-2' respectively.

[0110] <Manufacturing Example 1: Fabrication of Optical Functional Layer>

[0110] (1) Modulation of the composition for forming a high refractive index layer

[0110] The constituent systems for forming high refractive index layers in the following embodiments are each modulated using the following steps.

[0110] The photopolymerization initiator (BASF's "Irgacure 184") and diluent (methyl ethyl ketone / propylene glycol monomethyl ether acetate mass ratio = 5 / 1) were mixed and stirred. Then, the UV-curable resin (Nippon Kayaku Co., Ltd.'s "KAYARAD-DPHA") was added and stirred. Further, a zirconium oxide particle dispersion (CIK NanoTek Corporation's "ZRMIBK 15WT%-PO3", solids 15% by mass, average primary particle size 7.8 nm) was added and stirred to prepare a composition for forming a high refractive index layer.

[0111] (2) Fabrication of laminates A-1 to A-5

[0111] A high-refractive-index layer forming composition was coated onto a 40 μm thick triacetyl cellulose membrane (refractive index 1.49 at 550 nm, hereinafter also referred to as "TAC membrane") using a rod coater, dried, and irradiated with ultraviolet light to produce a laminate A-1 consisting of a substrate membrane and a high-refractive-index layer having the optical film thickness shown in Table 1. Similarly, a high-refractive-index layer forming composition was coated onto the TAC membrane, dried, and irradiated with ultraviolet light to produce laminates A-2 to A-5. The refractive index and optical film thickness of the high-refractive-index layer at 550 nm are shown together in Table 1.

[0112] (3) Fabrication of optical functional layers A-1' to A-5'

[0112] On the side of laminate A-1 opposite to the high refractive index layer (i.e., the side facing the substrate film), with an adhesive layer (refractive index 1.47 at 550 nm), a cyclic polyolefin resin film (HC-COP) with a hard coating is bonded [in-plane phase difference Re at 590 nm: 100 nm, HC layer thickness: 3 μm]. Furthermore, an adhesive layer (refractive index 1.47 at 550 nm, haze 0.2%) is laminated onto the high refractive index layer of laminate A-1. An alkali-free glass plate (refractive index 1.51 at 550 nm) is bonded to the adhesive layer, resulting in an optical functional layer A-1' composed of a glass plate / adhesive layer / high refractive index layer / substrate film / adhesive layer / HC-COP.

[0112] The optical functional layer A-2' is obtained in the same manner as described above, except that a laminate A-2 is used.

[0112] The optical functional layer A-3' is obtained in the same manner as described above, except that a laminate A-3 is used.

[0112] The optical functional layer A-4' is obtained in the same manner as described above, except that a laminate A-4 is used.

[0112] The optical functional layer A-5' is obtained in the same manner as described above, except that a laminate A-5 is used.

[0113] (4) Fabrication of optical functional layers A-2” to A-5”

[0113] On the side of the laminate A-2 opposite to the high refractive index layer (i.e., the side of the substrate film), with an adhesive layer (refractive index 1.47 at a wavelength of 550 nm), a cyclic polyolefin resin film (HC-COP) with a hard coating (HC) layer is bonded to obtain an optical functional layer A-2 composed of a high refractive index layer / substrate film / adhesive layer / HC-COP.

[0113] The optical functional layer A-3 is obtained in the same manner as described above, except that a laminate A-3 is used.

[0113] The optical functional layer A-4 is obtained in the same manner as described above, except that a laminate A-4 is used.

[0113] The optical functional layer A-5 is obtained in the same manner as described above, except that a laminate A-5 is used.

[0114] (5) Fabrication of Optical Functional Layer B-1”

[0114] Technolloy C000 (polycarbonate resin film, overall thickness: 75 μm) manufactured by SUMIKA ACRYL Co., Ltd. (a single-layer film, but conveniently referred to as laminate B-1) was used as laminate B-1. The refractive index and optical film thickness of laminate B-1 at a wavelength of 550 nm are shown together in Table 1. The optical film thickness was measured using a contact thickness gauge. The refractive index was measured according to JIS K7142.

[0115] A cyclic polyolefin resin film (HC-COP) with a hard coating is bonded to one side of the laminate B-1 with an adhesive layer (refractive index 1.47 at a wavelength of 550 nm) in between, to obtain an optical functional layer B-1 composed of laminate B-1 / adhesive layer / HC-COP.

[0116] (6) Fabrication of Optical Functional Layer B-2”

[0116] A high-refractive-index layer forming composition was coated onto a 40 μm thick TAC film (refractive index 1.49 at 550 nm) as the substrate film using a bar coater, dried, and irradiated with ultraviolet light to produce a laminate B-2 consisting of a substrate film and a high-refractive-index layer having the optical film thicknesses shown in Table 1. The refractive index and optical film thickness of the high-refractive-index layer at 550 nm are shown together in Table 1.

[0117] A cyclic polyolefin resin film (HC-COP) with a hard coating is bonded to one side of the laminate B-2 with an adhesive layer (refractive index 1.47 at a wavelength of 550 nm) in between, to obtain an optical functional layer B-2 composed of laminate B-2 / adhesive layer / HC-COP.

[0118] [Table 1]

[0119] The reflectance R(450), reflectance R(550) and reflectance R(630) of each optical functional layer, and the reflectance ratio (reflectance R(450) / reflectance R(550)) are shown in Table 2.

[0120] [Table 2]

[0121] <Manufacturing Example 2: Fabrication of a Linear Polarizing Plate>

[0121] (1) Fabrication of linear polarizer

[0121] A 20 μm thick polyvinyl alcohol (PVA) resin film (average degree of polymerization approximately 2400, degree of saponification ≥ 99.9 moles) was uniaxially stretched longitudinally by approximately 5 times using a dry stretching method. While maintaining tension, the film was immersed in pure water at 60°C for 1 minute, followed by immersion in an aqueous solution at 28°C with a mass ratio of iodine / potassium iodide / water of 0.05 / 5 / 100 for 60 seconds. Then, it was immersed in an aqueous solution at 72°C with a mass ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 for 300 seconds. After washing with pure water at 26°C for 20 seconds, the film was dried at 65°C to obtain a linear polarizer with iodine adsorbed and oriented on the PVA resin film and a thickness of 8 μm. The resulting linear polarizer has a transmittance Ty of 42.5%, a polarization Py of 99.99%, an orthogonal hue a* of 0.1, and an orthogonal hue b* of -0.3.

[0122] (2) Preparation of water-based adhesives

[0122] A polyvinyl alcohol aqueous solution was prepared by dissolving 3 parts by weight of carboxyl-modified polyvinyl alcohol (KL-318 manufactured by Kuraray Co., Ltd.) in 1.5 parts by weight of water in 100 parts by weight of the aqueous solution. A water-soluble polyamine epoxy resin (Sumirez Resin 650 (30) manufactured by Taoka Chemical Co., Ltd., with a solids concentration of 30% by weight) was mixed in 1.5 parts by weight of water in 100 parts by weight of the aqueous solution to obtain a water-based adhesive.

[0123] (3) Fabrication of linear polarizing plate

[0123] The aqueous adhesive obtained above is applied to one side of the linear polarizer, and a cyclic polyolefin resin film (HC-COP) with a hard coating (HC) layer is laminated. The aqueous adhesive obtained above is applied to the other sides of the linear polarizer, and a TAC film is laminated. By drying at 80°C for 5 minutes, a linear polarizer with protective films on both sides of the linear polarizer is obtained. The layer structure of the linear polarizer is HC-COP / aqueous adhesive layer / linear polarizer / aqueous adhesive layer / TAC film. A protective film with an adhesive layer on the substrate film is laminated on the HC layer of the linear polarizer to obtain a linear polarizer with a protective film (hereinafter also referred to as "linear polarizer with PF").

[0123] Furthermore, in this linear polarizing plate, the reflectivity of the aqueous adhesive layer was not measured to be a meaningful value.

[0124] <Manufacturing Example 3: Fabrication of Phase Difference Stacked Sheets>

[0124] (1) Fabrication of the first phase difference layer

[0124] An alignment layer is formed on a first substrate layer made of transparent resin, and a composition for forming a first retardation layer containing a rod-shaped nematic polymerizable liquid crystal compound is coated thereon to fabricate a first retardation layer with the first substrate layer attached. The first retardation layer is a λ / 4 layer. The thickness of the first retardation layer is 2 μm. The wavelength dispersion α of the first retardation layer [in-plane phase difference value Re(450) / in-plane phase difference value Re(550)] is 0.85, and Re(550) is 142 nm (average value of 12 locations in-plane).

[0125] Furthermore, regarding the first retardation layer, a 140mm × 70mm section was cut out, and the in-plane phase difference value of the first retardation layer was measured at 12 locations within the plane. After measuring and calculating the dispersion of the in-plane phase difference value Re(550), the maximum was 143nm and the minimum was 141nm. The difference between the maximum and minimum was 2nm. The details of the fabrication of the first retardation layer are shown below.

[0126] [Modulation of composition (X) for alignment layer formation]

[0126] The photoalignment material with the following structure (weight average molecular weight: 50,000, m:n = 50:50) was manufactured according to the method described in Japanese Patent Application Publication No. 2021-196514. Two parts by mass of the photoalignment material and 98 parts by mass of cyclopentanone (solvent) were mixed as components, and the resulting mixture was stirred at 80°C for 1 hour to prepare a composition (X) for forming an alignment layer.

[0126] Photoalignment materials:

[0126]

[0127] [Manufacturing of Nematic Polymerizable Liquid Crystal Compounds]

[0127] Polymerizable liquid crystal compounds (A1) and (A2) having the structures shown below are prepared respectively. Polymerizable liquid crystal compound (A1) is prepared in the same manner as described in Japanese Patent Application Publication No. 2019-003177. Polymerizable liquid crystal compound (A2) is prepared in the same manner as described in Japanese Patent Application Publication No. 2009-173893.

[0127] Polymerizable liquid crystal compound (A1):

[0127]

[0127] Polymerizable liquid crystal compound (A2):

[0127]

[0128] A solution was obtained by dissolving 1 mg of a polymeric liquid crystal compound (Al) in 10 mL of chloroform. The resulting solution was placed into a measuring tank with a 1 cm optical path length for the test sample, and the test sample was placed in a UV-Vis spectrophotometer (Shimadzu Corporation, "UV-2450") to measure the absorption spectrum. The wavelength of maximum absorbance was read from the obtained absorption spectrum, and the maximum absorption wavelength λmax in the wavelength range of 300 to 400 nm was 356 nm.

[0129] [Modulation of the composition (Y) for forming the first phase difference layer]

[0129] Polymerizable liquid crystal compound (A1) and polymerizable liquid crystal compound (A2) were mixed at a mass ratio of 93:7 to obtain a mixture. 0.1 parts by mass of a leveling agent "BYK-361N" (manufactured by BM Chemie) and 3 parts by mass of "IrgacureOXE-03" (manufactured by BASF JAPAN Co., Ltd.) as a photopolymerization initiator were added relative to 100 parts by mass of the obtained mixture. Furthermore, N-methyl-2-pyrrolidone (NMP) was added to achieve a solids concentration of 13% by mass. The mixture was stirred at 80°C for 1 hour to prepare the composition (Y) for forming the first phase retardation layer.

[0130] [Production of the First Phase Difference Layer]

[0130] The above-mentioned alignment layer forming composition (X) was applied to a biaxially extended polyethylene terephthalate (PET) film (manufactured by Diafoil Mitsubishi Resin Co., Ltd.) serving as the first substrate layer using a bar coater. The resulting coated film was dried at 120°C for 2 minutes and then cooled to room temperature to form a dried film. Subsequently, the alignment layer was obtained by irradiating it with 100 mJ of polarized ultraviolet light (313 nm reference) using a UV irradiation device (SPOT CURE SP-9; manufactured by USHIO INC.). The film thickness of the alignment layer, measured using an ellipsometry M-220 manufactured by Nippon Spectrophotometer Co., Ltd., was 100 nm.

[0131] The composition (Y) for forming the first retardation layer was coated onto the obtained alignment layer using a bar coater to form a coated film. After heating and drying the coated film at 120°C for 2 minutes, it was cooled to room temperature to obtain a dried film. Next, using a high-pressure mercury lamp (UniQureVB-15201BY-A manufactured by USHIO INC.), the dried film was irradiated with ultraviolet light with an exposure of 500 mJ / cm2 (365 nm reference) under a nitrogen atmosphere. The polymerizable liquid crystal compound was aligned in a horizontal direction relative to the substrate plane to form a hardened first retardation layer, resulting in a first retardation layer consisting of a first substrate layer / alignment layer / first retardation layer (horizontally aligned liquid crystal hardened film) with the first substrate layer attached. The thickness of the first retardation layer was measured to be 2.0 μm using a laser microscope LEXT OLS4100 manufactured by Olympus Corporation.

[0132] (2) Fabrication of the second phase difference layer

[0132] A second phase difference layer with a second substrate layer is fabricated by the following method.

[0133] [Modulation of the composition (Y2) for forming the second phase difference layer]

[0133] 100 parts by mass of a mixed polymeric liquid crystal compound Paliocolor LC242 (manufactured by BASF Japan Co., Ltd.), 0.1 part by mass of a leveling agent “BYK-361N” (manufactured by BYK-Chemie GmbH), and 2.5 parts by mass of a photoinitiator “Omnirad 907” (manufactured by IGM Resin B.V.). Further, 400 parts by mass of propylene glycol monomethyl ether acetate (PGME) was added, and the resulting mixture was stirred at 80° C. for 1 hour to prepare a composition (Y2) for forming a second retardation layer.

[0133] Polymeric liquid crystal compound LC242:

[0133]

[0134] [Preparation of Composition (X2) for Forming Alignment Layer]

[0134] 2-Butoxyethanol was added to Sunever-SE-610 (manufactured by Nissan Chemical Industries, Ltd.), a commercially available alignment polymer, so that the solid content was 1% by mass to obtain a composition (X2) for forming an alignment layer.

[0135] [Production of Second Retardation Layer]

[0135] As the second base material layer, a cycloolefin polymer (COP) (ZF14, manufactured by Zeon Corporation) was used. Corona treatment was performed on one surface thereof using a corona treatment device (AGF-B10; manufactured by Kasuga Electric Co., Ltd.). On the surface thereof, the composition (X2) for forming an alignment layer was applied using a bar coater and dried at 90° C. for 1 minute. After measuring the film thickness of the obtained alignment layer with a laser microscope, it was 30 nm. Subsequently, the composition (Y2) for forming a second retardation layer was applied on the alignment layer using a bar coater, dried at 90° C. for 1 minute, and then irradiated with ultraviolet light having an exposure amount of 1000 mJ / cm2 (based on 365 nm) in a nitrogen atmosphere using a high-pressure mercury lamp (Ushio Inc. “UniQure VB-15201BY-A”) on the dried film to obtain a second retardation layer with a second base material layer attached thereto. After measuring the film thickness with a laser microscope, the film thickness of the second retardation layer was 450 nm. The in-plane retardation value was measured using KOBRA-WR manufactured by Oji Scientific Instruments Co., Ltd. As a result, Re(550)=1 nm and Rth(550)=−75 nm. Therefore, the second retardation layer with the second base material layer attached thereto has optical properties represented by nx≈ny<nz. Further, since the retardation value of the COP at a wavelength of 550 nm is slightly 0, it does not affect the optical properties.

[0136] (3) Preparation of UV-curing adhesive

[0136] Mix the following cationic curing components to prepare a UV-curing adhesive.

[0136] 3,4-Epoxycyclohexanecarboxylic acid-3',4'-epoxycyclohexylmethyl ester (trade name: CEL2021P, manufactured by Daicel Corporation): 70 parts by weight

[0136] Neopentyl glycol diglycidyl ether (trade name: EX-211, manufactured by Nagase ChemteX Corporation): 20 parts by weight

[0136] 2-Ethylhexyl glycidyl ether (trade name: EX-121, manufactured by Nagase ChemteX Corporation): 10 parts by weight

[0136] Catonic polymerization initiator (trade name: CPI-100, 50% solution, manufactured by San-Apro Corporation): 4.5 parts by weight (actual solids 2.25 parts by weight)

[0136] 1,4-Ethoxynaphthalene: 2.0 parts by weight

[0137] (4) Fabrication of phase difference stacked layers

[0137] Corona treatment is performed on both the phase retardation layer side of the first phase retardation layer with the first substrate layer and the phase retardation layer side of the second phase retardation layer with the second substrate layer. A modified ultraviolet-curable adhesive is coated onto one of the corona-treated surfaces, and the first phase retardation layer with the first substrate layer and the second phase retardation layer with the second substrate layer are then bonded together. Ultraviolet light is irradiated from the second substrate layer side to cure the ultraviolet-curable adhesive, thereby forming an adhesive layer. The thickness of the cured ultraviolet-curable adhesive layer is 1.5 μm.

[0138] <Example 1>

[0138] (1) Fabrication of optical laminates

[0138] An adhesive layer containing a light-selective absorber (A(410)=1.10, thickness 15μm) is bonded to the surface of the linear polarizer obtained in Manufacturing Example 2 on the TAC film side. Next, the first substrate layer of the phase difference stack obtained in Manufacturing Example 3 is peeled off, and the linear polarizer is deposited on the exposed alignment layer in such a way that the adhesive layer containing the light-selective absorber is in contact with the ground.

[0139] Next, the laminate A-1 is deposited on the HC layer of the linear polarizer with the TAC film side contact, through an adhesive layer (storage modulus: 25,500 Pa, refractive index 1.47 at 550 nm, haze 0.2%, and without light-selective absorbers). Furthermore, an adhesive layer (storage modulus: 25,500 Pa, refractive index 1.47 at 550 nm, haze 0.2%, and without light-selective absorbers) is deposited on top of the high-refractive-index layer of the laminate A-1. An alkali-free glass plate (refractive index 1.51 at 550 nm) is then bonded to the adhesive layer to obtain an optical laminate containing the optical functional layer A-1'.

[0140] (2) Measurement and evaluation of reflectance properties

[0140] The reflectance Y and reflected hues a* and b* of the optical laminate obtained in (1) above were measured using a "Cm2600d" manufactured by Konica Minolta. The results are shown in Table 4. During the measurement, a glass plate (thickness 0.7 mm, "EAGLE XG" manufactured by Corning) was attached to the side of the optical laminate opposite to the side where light is incident (the side of the optical laminate opposite to the optical functional layer) through an adhesive layer (storage modulus: 25,500 Pa, refractive index 1.47 at a wavelength of 550 nm, haze 0.2%, without light selective absorber). The optical laminate with the glass plate attached obtained above was placed on a reflector (reflectance: 96% or more, diffuse reflectance: 9% or less) with the optical functional layer above, and the measurement was performed in a state where the layers were configured as reflector / air / glass plate / optical laminate. The reflectance Y of the optical laminate was evaluated according to the following criteria. The results are shown in Table 4.

[0140] A: The reflectance Y is less than 6.0%.

[0140] B: The reflectance Y is 6.0% or higher.

[0141] (3) Measurement and evaluation of light leakage

[0141] In step (1) above, the second substrate layer is peeled off from the obtained optical laminate, and an aluminum foil (UACJ Corporation's "My Foil Thick 50", 20 μm thick) is laminated on its non-glossy side as a reflector. Under fluorescent light, the slight light leakage is visually observed from 30 cm above the viewing side of the optical laminate (the side opposite to the aluminum foil), and evaluated according to the following criteria. The results are shown in Table 4.

[0141] A: Light leakage will not be perceived.

[0141] B: Light leakage will be visually recognized.

[0142] <Examples 2, 3, 5, 6>

[0142] Except that each of the laminates A-2, A-3, A-4, and A-5 was used to replace laminate A-1, optical laminates containing optical functional layers A-2', A-3', A-4', and A-5' were fabricated in the same manner as in Example 1, and the reflection properties and light leakage were measured and evaluated. The results are shown in Table 4.

[0143] <Example 4>

[0143] An adhesive layer containing a light-selective absorber (A(410) = 1.10, thickness 15 μm) was bonded to the surface of the linear polarizer obtained in Manufacturing Example 2 on the TAC film side. Next, in Manufacturing Example 3, the first substrate layer of the phase difference stack was peeled off, and the linear polarizer was laminated on the exposed alignment layer in such a way that the adhesive layer containing the light-selective absorber was in contact with the ground.

[0144] Next, on the HC layer of the linear polarizer, the laminate A-3 is laminated with the TAC film side in contact with the adhesive layer (storage modulus: 25,500 Pa, refractive index 1.47 at wavelength 550 nm, haze 0.2%, and does not contain light selective absorber) to obtain an optical laminate containing the optical functional layer A-3”.

[0145] <Examples 7, 8>

[0145] Except that laminates A-4 and A-2 were used to replace laminate A-3, optical laminates containing optical functional layers A-4” and A-2” were fabricated in the same manner as in Example 4, and the reflection properties and light leakage were measured and evaluated. The results are shown in Table 4.

[0146] <Comparative Example 1>

[0146] In Manufacturing Example 2, an adhesive layer containing a light-selective absorber (A(410) = 1.10, thickness 15 μm) was bonded to the surface of the linear polarizer on the TAC film side. Next, the first substrate layer of the phase difference stack obtained in Manufacturing Example 3 was peeled off, and the linear polarizer was laminated on the exposed alignment layer in a contact manner with the adhesive layer containing the light-selective absorber to form an optical stack. The reflection properties and light leakage were measured and evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0147] <Comparative Example 2>

[0147] An optical laminate was fabricated by laminating an alkali-free glass plate (refractive index 1.51 at 550 nm) onto the linear polarizing plate of the optical laminate of Comparative Example 1, with an adhesive layer (storage modulus: 25,500 Pa, refractive index 1.47 at 550 nm, haze 0.2%, and containing no light-selective absorber). The reflection properties and light leakage were measured and evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0148] Regarding the partial laminated structures contained in the optical laminates of Comparative Example 1 and Comparative Example 2, the reflectance R (450), reflectance R (550) and reflectance R (630), as well as the reflectance ratio (reflectance R (450) / reflectance R (550)) were measured and are shown in Table 3.

[0148] Comparative Example 1: HC-COP

[0148] Comparative Example 2: Glass Plate / Adhesive Layer / HC-COP

[0149] [Table 3]

[0150] <Comparative Examples 3 to 5>

[0150] Except that each of the laminates B-1, B-2, and A-5 was used to replace laminate A-3, optical laminates containing optical functional layers B-1”, B-2”, and A-5” were fabricated in the same manner as in Example 4, and the reflection properties and light leakage were measured and evaluated. The results are shown in Table 4.

[0151] [Table 4]

Claims

1. An optical laminate, comprising, in sequence, an optical functional layer (A), a linear polarizer, and a phase retardation layer with inverse wavelength dispersion, wherein, The ratio of the reflectance R(450) of the aforementioned optical functional layer (A) at a wavelength of 450 nm to the reflectance R(550) at a wavelength of 550 nm is: R(450) / R(550) is more than 1.07 and less than 1.55, and the aforementioned reflectance R(550) is less than 6.0%.

2. The optical laminate as described in claim 1, wherein, The aforementioned optical functional layer (A) is a high refractive index layer containing a refractive index of 1.6 or higher at a wavelength of 550 nm.

3. The optical laminate as described in claim 2, wherein, The aforementioned optical functional layer (A) comprises a substrate film and the aforementioned high refractive index layer deposited thereon.

4. The optical laminate as described in claim 1, wherein, The ratio of the aforementioned reflectivity R(450) to the aforementioned reflectivity R(550) is R(450) / R(550) greater than 1.07 and less than 1.

35.

5. The optical laminate as described in claim 1, wherein, The aforementioned phase difference layer system includes one or more liquid crystal curing layers.

6. The optical laminate as described in claim 1, wherein, The aforementioned optical functional layer (A) further includes a front panel.

7. The optical stack as described in claim 1 further comprises an adhesive layer disposed on the side opposite to the linear polarizer of the aforementioned phase retardation layer.

8. The optical laminate as described in claim 7 further comprises a separation membrane disposed on the side of the aforementioned adhesive layer opposite to the aforementioned phase difference layer.

9. The optical laminate as described in claim 1, further comprising a protective film on the side of the aforementioned optical functional layer (A) opposite to the aforementioned linear polarizer.

10. An image display device comprising the optical laminate described in any one of claims 1 to 9.

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