CN117957469A

CN117957469A - Optical laminate and image display device

Info

Publication number: CN117957469A
Application number: CN202280063073.8A
Authority: CN
Inventors: 白石贵志; 祖父江彰二
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2021-10-01
Filing date: 2022-09-29
Publication date: 2024-04-30

Abstract

The present invention provides an optical laminate capable of functioning as a circular polarizing plate, ensuring sufficiently small reflectance when applied to an image display device, and being less likely to observe slight leakage of internal reflected light due to slight deviation of reflection color tone in the plane of the circular polarizing plate, and an image display device including the optical laminate. An optical laminate comprising, in order, an optical functional layer (A) having a ratio of a reflectance R (450) at a wavelength of 450nm to a reflectance R (550) at a wavelength of 550nm, a linear polarizer, and a retardation layer having inverse wavelength dispersion, and an image display device comprising the optical laminate are provided: r (450)/R (550) is 1.07 or more and 1.55 or less, and the reflectance R (550) is less than 6.0%.

Description

Optical laminate and image display device

Technical Field

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

Background

In an image display device typified by an organic Electroluminescence (EL) display device, it is known to use a circularly polarizing plate or the like to improve antireflection performance in order to suppress a decrease in visibility due to reflection of external light (for example, japanese patent application laid-open No. 2020-134934 (patent document 1)). The circularly polarizing plate is an optical laminate including a linearly polarizing plate and a phase difference layer.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2020-134934

Disclosure of Invention

Problems to be solved by the invention

The circularly polarizing plate is generally disposed on the viewing side of an image display device such as an organic EL display device. By disposing the circularly polarizing plate in this manner, it is possible to suppress internal reflection light that is reflected by an internal electrode or the like included in the image display element and is emitted to the outside. In particular, it is known that if the circularly polarizing plate has a structure including a λ/4 layer having inverse wavelength dispersion, internal reflection light can be suppressed in a wide visible range, and thus black display can be easily realized (the reflection color tone of the circularly polarizing plate is made neutral).

However, there are the following problems: the more neutral the reflection color tone of the circular polarizing plate, the more easily the light leakage of the internal reflection light (hereinafter, also referred to as "light leakage") caused by the slight deviation of the reflection color tone in the plane of the circular polarizing plate is observed as unevenness.

The present invention has an object to provide an optical laminate which can be used as a circularly polarizing plate and which, when applied to an image display device, is less likely to observe the slight light leakage while ensuring a sufficiently small reflectance. Another object of the present invention is to provide an image display device including the optical laminate.

Means for solving the problems

The present invention provides the following optical layered body and image display device.

[1] An optical laminate comprising, in order, an optical functional layer (A), a linear polarizer and a retardation layer having inverse wavelength dispersion,

The ratio of the reflectance R (450) at the wavelength of 450nm to the reflectance R (550) at the wavelength of 550nm of the optical functional layer (A): r (450)/R (550) is 1.07 or more and 1.55 or less,

The reflectance R (550) is less than 6.0%.

[2] The optical laminate according to [1], wherein the optical functional layer (A) comprises a high refractive index layer having a refractive index of 1.6 or more at a wavelength of 550 nm.

[3] The optical laminate according to [2], wherein the optical functional layer (A) comprises a base film and the high refractive index layer laminated thereon.

[4] The optical laminate according to any one of [1] to [3], wherein the ratio of the reflectance R (450) to the reflectance R (550): r (450)/R (550) is 1.07 or more and 1.35 or less.

[5] The optical laminate according to any one of [1] to [4], wherein the retardation layer comprises 1 or more liquid crystal cured layers.

[6] The optical laminate according to any one of [1] to [5], wherein the optical functional layer (A) further comprises a front plate.

[7] The optical laminate according to any one of [1] to [6], further comprising an adhesive layer disposed on the opposite side of the retardation layer from the linear polarizer.

[8] The optical laminate according to [7], further comprising a separator disposed on the opposite side of the pressure-sensitive adhesive layer from the retardation layer.

[9] The optical laminate according to any one of [1] to [8], further comprising a protective film on a surface of the optical functional layer (A) opposite to the linear polarizer.

[10] An image display device comprising the optical laminate according to any one of [1] to [9 ].

Effects of the invention

An optical laminate that can be used as a circularly polarizing plate and that is less likely to observe the slight light leakage while ensuring sufficiently small reflectance when applied to an image display device, and an image display device including the optical laminate can be provided.

Drawings

Fig. 1 is a schematic cross-sectional view showing an example of an optical laminate of the present invention.

Fig. 2 is a schematic cross-sectional view showing another example of the optical laminate of the present invention.

Fig. 3 is a schematic cross-sectional view showing still another example of the optical laminate of the present invention.

Fig. 4 is a schematic cross-sectional view showing still another example of the optical laminate of the present invention.

Fig. 5 is a schematic cross-sectional view showing still another example of the optical laminate of the present invention.

Fig. 6 is a schematic cross-sectional view showing an example of the image display device of the present invention.

Detailed Description

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 drawings below are shown to help understanding the present invention, and the size and shape of each component shown in the drawings do not necessarily coincide with the size and shape of the actual component.

< Optical laminate >)

The optical laminate of the present invention (hereinafter, also simply referred to as "optical laminate") can be used as a circularly polarizing plate, and comprises, in order, an optical functional layer (a), a linear polarizer, and a retardation layer having inverse wavelength dispersion. The term "circular polarizing plate" includes elliptical polarizing plates.

Fig. 1 is a schematic cross-sectional view showing an example of an optical laminate of the present invention. The optical laminate shown in fig. 1 includes an optical functional layer (a) 1, a linear polarizer 2, and a retardation layer 3 having inverse wavelength dispersion. The optical functional layer (a) 1 and the linear polarizer 2 may be laminated via the 1 st lamination layer 10. The linear polarizer 2 and the retardation layer 3 may be laminated via the 2 nd lamination layer 20. When the optical laminate is applied to an image display device (such as an organic EL display device), the optical functional layer (a) 1 side of the optical laminate is arranged on the observation side of the image display device, that is, the phase difference layer 3 side is arranged on the image display device (such as an organic EL display device).

Hereinafter, components included or capable of being included in the optical laminate will be described in detail.

(1) Optical functional layer (A)

The optical functional layer (a) is a layer disposed on the observation side of the linear polarizer 2, and has the following reflection characteristics.

The ratio of the reflectance R (450) at a wavelength of 450nm to the reflectance R (550) at a wavelength of 550nm (reflectance R (450)/reflectance R (550). Hereinafter, also simply referred to as "reflectance ratio") is 1.07 or more and 1.55 or less.

The reflectance R (550) is less than 6.0%.

The optical functional layer (a) generally has a laminated structure. When the reflectance of the 1 st adhesive layer 10 is a significant (meaning of japanese: no), the laminated structure composed of the optical functional layer (a) 1 and the 1 st adhesive layer 10, that is, the laminated structure composed of all layers disposed on the observation side of the linear polarizer 2 corresponds to the "optical functional layer (a)". On the other hand, when the reflectance of the 1 st bonding layer 10 is not a significant value, that is, when the reflectance of the optical functional layer (a) 1 is substantially equal to the reflectance of the above-described laminated structure, the optical functional layer (a) 1 may be regarded as the optical functional layer (a).

By providing the optical functional layer (a) 1 having the above-described reflection characteristics on the observation side of the linear polarizer 2, the reflected light reflected on the observation side surface of the optical laminate can be made blue, and therefore the slight light leakage described above can be made less likely to be observed. Since the optical laminate of the present invention is provided with the retardation layer having inverse wavelength dispersion, internal reflection can be significantly suppressed, and thus the method of the present invention for controlling reflected light reflected on the observation side surface of the optical laminate by imparting the optical functional layer (a) 1 is effective in that slight light leakage is not easily observed. On the other hand, even if the optical functional layer (a) 1 is disposed on the observation side of the linear polarizer 2, the change of the transmitted light (white display) from the image display element to bluish color can be suppressed.

By adjusting the phase difference characteristics of the phase difference layer of the circularly polarizing plate, the reflection color tone of the circularly polarizing plate can be bluish. For example, by increasing the wavelength dispersion α, a bluish color can be obtained. However, in this case, there is another problem that the change in the reflected color tone from the oblique direction becomes large. According to the method of imparting the optical functional layer (a) 1 having the above-described reflection characteristics to the viewing side of the linear polarizer 2, slight light leakage can be made less likely to be observed without causing such a problem.

The wavelength dispersion α is a ratio of an in-plane phase difference value Re (450) at a wavelength of 450nm and an in-plane phase difference value Re (550) at a wavelength of 550 nm.

Wavelength dispersion α=in-plane phase difference Re (450)/in-plane phase difference Re (550)

Further, according to the optical laminate of the present invention, the reflection color tone of the optical laminate can be appropriately changed to a bluish color, and therefore, a high-quality feeling can be imparted to the display of the image display device. The bluing degree of the reflection hue can be controlled by adjusting the reflectance R (450), the reflectance R (550), and/or the reflectance ratio thereof within the above-described range.

The reflectance ratio is preferably 1.07 or more and 1.45 or less, more preferably 1.07 or more and 1.35 or less, still more preferably 1.10 or more and 1.35 or less, and still more preferably 1.12 or more and 1.35 or less, from the viewpoint of preventing slight light leakage and/or from moderately reducing the reflectance Y of the optical laminate. If the reflectance ratio exceeds 1.55, there is a tendency that the reflection tone of the optical laminate becomes too strong to turn blue. If the reflectance ratio is less than 1.07, an effect that slight light leakage is not easily observed cannot be obtained.

From the viewpoint of moderately reducing the reflectance Y of the optical laminate, the reflectance R (550) is preferably 5.8% or less, more preferably 5.6% or less, and even more preferably 5.4% or less. If the reflectance R (550) is 6.0% or more, the reflectance Y of the optical laminate becomes too large, and the visibility of the image display device tends to be lowered. The reflectance R (550) may be 0.0%, but is usually more than 0.0%, for example, 0.1% or more, preferably 1.0% or more, more preferably 4.0% or more, and still more preferably 4.2% or more.

From the viewpoint of not easily observing light leakage and/or the viewpoint of moderately reducing the reflectance Y of the optical laminate, the reflectance 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 still more preferably 5.0% or more and 8.0% or less.

From the viewpoint of visibility of the image display device, the reflectance Y of the optical laminate is preferably less than 6.0%, more preferably 5.9% or less, further preferably 5.8% or less, and still further preferably 5.7% or less. The reflectance Y is usually 4.0% or more.

The reflectance R (450) and the reflectance R (550) of the optical functional layer (a) and the reflectance Y of the optical laminate can be measured by the method described in one of the following [ examples ].

The optical functional layer (a) 1 may include, for example, a high refractive index layer, a pigment-containing layer (for example, a yellow pigment-containing layer), an alternating multilayer of a high refractive index layer and a low refractive index layer, a liquid crystal layer, a fluorescent layer, or a combination thereof. The high refractive index layer utilizes interfacial reflection to achieve the above-described reflection characteristics. The pigment-containing layer is, for example, a layer containing a pigment that absorbs yellow light, and is a layer that enhances the blue emission of reflected light. Alternating multilayers of high refractive index layers and low refractive index layers utilize interfacial reflection at the interface of the high refractive index layers and low refractive index layers to achieve the above-described reflection characteristics. The liquid crystal layer realizes the above reflection characteristics by, for example, reflection of circularly polarized light by cholesteric liquid crystal. Among them, the optical functional layer (a) 1 preferably includes a high refractive index layer from the viewpoints of easiness in manufacturing and easiness in realizing the optical functional layer (a) having the above-described reflection characteristics, easiness in adjusting the reflection color tone of the optical laminate, and preferably, no coloring of transmitted light from the image display element.

As the high refractive index layer, a conventionally known high refractive index layer may be used, and a layer in which a refractive index imparting agent is dispersed in a binder resin is preferable. Examples of the refractive index imparting agent include particles made 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 diameter of the particles is, for example, 0.01nm to 100nm, preferably 0.1nm to 50 nm.

The content of the refractive index imparting agent in the high refractive index layer is preferably 10 mass% or more and 90 mass% or less, more preferably 20 mass% or more and 80 mass% or less, still more preferably 30 mass% or more and 70 mass% or less, still more preferably 40 mass% or more and 60 mass% or less, in 100 mass% of the high refractive index layer, from the viewpoints of the refractive index of the high refractive index layer and the ease of film formation of the layer. The refractive index of the high refractive index layer may 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.

The binder resin may be a thermoplastic resin or a cured product of a curable resin. The high refractive index layer may have a hard coating property, and in this case, the high refractive index layer may be formed from a cured product of a composition for forming a hard coating layer containing an active energy ray curable resin such as an ultraviolet curable resin and a refractive index imparting agent. Examples of the active energy ray-curable resin include (meth) acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins, and ultraviolet-curable resins are preferable. The ultraviolet curable resin constituting the binder resin is preferably a (meth) acrylic resin, and more preferably a (meth) acrylic resin containing a structural unit derived from a polyfunctional (meth) acrylic monomer from the viewpoint of curability.

In the present specification, "(meth) acrylic acid" means either acrylic acid or methacrylic acid. (meth) acrylate and the like are also defined as "(meth)" as well.

From the viewpoint of the refractive index of the high refractive index layer and the viewpoint of light leakage being less likely to be observed, the thickness (optical film thickness) of the high refractive index layer is preferably 10nm or more and 1000nm or less, more preferably 10nm or more and 500nm or less, still more preferably 20nm or more and 300nm or less, still more preferably 40nm or more and 250nm or less, particularly preferably 100nm or more and 200nm or less.

The refractive index of the high refractive index layer at 550nm is preferably 1.6 or more, more preferably 1.62 or more, from the viewpoint that light leakage is not easily observed. The refractive index is preferably 1.75 or less, more preferably 1.70 or less, from the viewpoint of making the reflection color of the optical laminate moderately bluish.

The optical functional layer (a) 1 is generally directly laminated on the surface of the linear polarization plate 2. For example, the high refractive index layer-forming composition can be applied to the surface of the linear polarizer 2, and dried and/or cured as necessary, whereby the high refractive index layer can be directly laminated on the surface of the linear polarizer 2.

The optical functional layer (a) 1 may include a base film and a high refractive index layer laminated thereon. In this case, the optical functional layer (a) 1 may be laminated on the linear polarizer 2 via, for example, the 1 st adhesive layer 10 so that the substrate film side thereof faces the linear polarizer 2. The optical functional layer (a) including the substrate film and the high refractive index layer can be formed by applying the composition for forming a high refractive index layer to the substrate film and drying and/or curing the composition as necessary. Alternatively, the above-mentioned base film may be laminated on the observation side of the linear polarizer 2 as a protective film for the linear polarizer 2 to produce a linear polarizer, and the layers constituting the optical functional layer (a) 1 other than the base film may be bonded to the linear polarizer to produce an optical laminate. In this case, the optical functional layer (a) 1 has a layer constituting the optical functional layer (a) 1 other than the base film and the base film.

As the base film, a thermoplastic resin film described later can be used. From the viewpoint of thickness reduction, the thickness of the base film is usually 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, still more preferably 40 μm or less, still more preferably 30 μm or less, and further usually 5 μm or more, preferably 10 μm or more.

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

The optical functional layer (a) 1 may include a thermoplastic resin film other than the base film. For example, the thermoplastic resin film may be laminated as a protective film for the linear polarizer 2 on the observation side of the linear polarizer 2 to produce a linear polarizer, and the layer constituting the optical functional layer (a) 1 other than the thermoplastic resin film may be bonded to the linear polarizer to produce an optical laminate. In this case, the optical functional layer (a) 1 has a layer constituting the optical functional layer (a) 1 other than the thermoplastic resin film and the thermoplastic resin film. Details of the thermoplastic resin film will be described later.

When the optical functional layer (a) includes a high refractive index layer and a base film, the refractive index difference between them at a wavelength of 550nm is preferably 0.05 or more and 0.30 or less, more preferably 0.08 or more and 0.26 or less, and still more preferably 0.10 or more and 0.24 or less, from the viewpoint that light leakage is less likely to be observed.

When the optical functional layer (a) includes a high refractive index layer and a base film, a resin layer may be interposed between the high refractive index layer and the base film, or the resin layer may be disposed on the side of the high refractive index layer opposite to the base film. An example of the resin layer is a hard coat layer. The resin layer that can be interposed between the high refractive index layer and the base film may be an undercoat layer. The hard coat layer is described below.

When the optical functional layer (a) includes a base film and a resin layer, the base film and the resin layer are laminated on the observation side of the linear polarizer 2 as a protective film and a hard coat layer of the linear polarizer 2, respectively, to thereby produce a linear polarizer, and the layers constituting the optical functional layer (a) 1 other than the base film and the resin layer are bonded to the linear polarizer to produce an optical laminate. In this case, the optical functional layer (a) 1 includes the base film and the layers other than the resin layer constituting the optical functional layer (a) 1, the base film, and the resin layer.

In the case where the resin layer is included, the refractive index difference between the resin layer and the high refractive index layer at a wavelength of 550nm is preferably 0.05 or more and 0.30 or less, more preferably 0.08 or more and 0.26 or less, and still more preferably 0.10 or more and 0.24 or less, from the viewpoint that light leakage is not easily observed.

The optical functional layer (a) 1 may contain 1 or 2 or more layers capable of adjusting the reflection characteristics (reflectance Y, reflectance hue) of the optical laminate, in addition to the high refractive index layer, the pigment-containing layer (for example, the yellow pigment-containing layer), the alternating multilayer of the high refractive index layer and the low refractive index layer, the liquid crystal layer, the fluorescent layer, or a combination thereof. Examples of such a layer include the resin layer described above. The resin layer may be disposed between the high refractive index layer and the base film or on the opposite side of the high refractive index layer from the base film. The resin layer may be an adhesive layer.

Another example of the layer capable of adjusting the reflection characteristics of the optical laminate is a front panel 90 described below, which is disposed on the side of the high refractive index layer opposite to the base film via an adhesive layer (6 th bonding layer 80 described below). As another example of the layer capable of adjusting the reflection characteristics of the optical laminate, a thermoplastic resin film other than the above-mentioned base film may be mentioned.

The optical functional layer (a) 1 is preferably a layer having high electrical insulation, for example, a resistance value exceeding 1.0× ⁷ Ω/≡. In order to improve electrical insulation, it is preferable that the optical functional layer does not have a network structure such as a metal mesh layer, that is, that the optical functional layer is uniform over the entire surface.

(2) Linear polaroid

The linear polarizer 2 has a function of selectively transmitting linear polarized light in a certain direction from light rays of unpolarized light such as natural light. Examples of the linear polarizer include a stretched film or a stretched layer having a dichroic dye adsorbed thereon, a cured product containing a polymerizable liquid crystal compound, and a liquid crystal cured layer of a dichroic dye. The optical functional layer (a) 1 and the linear polarizer 2 may be laminated via the 1 st lamination layer 10.

A linear polarizer, which is a stretched film having a dichroic dye adsorbed thereto, can be generally produced by the following steps: a step of uniaxially stretching a polyvinyl alcohol resin film; a step of dyeing a polyvinyl alcohol resin film with a dichroic dye such as iodine to adsorb the dichroic dye; a step of treating the polyvinyl alcohol resin film having the dichroic dye adsorbed thereon with an aqueous boric acid solution; and a step of washing with water after the treatment with the aqueous boric acid solution.

The thickness of the stretched film to which the dichroic dye is adsorbed is usually 30 μm or less, preferably 18 μm or less, and more preferably 15 μm or less. The thickness is usually 1 μm or more, and may be 5 μm or more, for example.

The polyvinyl alcohol resin is obtained by saponifying a polyvinyl acetate resin. As the polyvinyl acetate resin, a copolymer of vinyl acetate and other monomers copolymerizable therewith may be used in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acid compounds, olefin compounds, vinyl ether compounds, unsaturated sulfone compounds, and (meth) acrylamide compounds having an ammonium group.

The saponification degree of the polyvinyl alcohol resin is usually 85 mol% or more and 100 mol% or less, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, or a polyvinyl formal, a polyvinyl acetal, or the like modified with an aldehyde may be used. The polymerization degree of the polyvinyl alcohol resin is usually 1000 to 10000, preferably 1500 to 5000.

The linear polarizer as the stretched layer having the dichroic dye adsorbed thereto can be generally produced by the following steps: a step of applying a coating liquid containing the polyvinyl alcohol resin onto a substrate layer; a step of uniaxially stretching the obtained laminated film; a step of dyeing the uniaxially stretched polyvinyl alcohol resin layer of the laminated film with a dichroic dye, thereby adsorbing the dichroic dye; a step of treating the film having the dichromatic pigment adsorbed thereon with an aqueous boric acid solution; and a step of washing with water after the treatment with the aqueous boric acid solution. The base material layer may be used as a protective film for the linear polarizer or may be peeled off from the linear polarizer. The material and thickness of the base material layer may be the same as those of the thermoplastic resin film described later.

The optical laminate may include a protective film laminated on one or both sides of a linear polarizer as a stretched film or a stretched layer to which a dichroic dye is adsorbed. As the protective film, a thermoplastic resin film described later can be used. The linear polarizer and the protective film may be laminated via a lamination layer described later.

As described above, the thermoplastic resin film (protective film) laminated on the observation side of the linear polarizer is contained in the optical functional layer (a). The thermoplastic resin film and the linear polarizer may be bonded by the 1 st bonding layer.

Examples of the thermoplastic resin constituting the thermoplastic resin film include cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyether sulfone resin; polysulfone resin; a polycarbonate resin; polyamide resins such as nylon and aromatic polyamide; polyimide resin; polyolefin resins such as polyethylene, polypropylene and ethylene-propylene copolymers; a cyclic polyolefin resin having a ring system and a norbornene structure (also referred to as a norbornene-based resin); (meth) acrylic resins; a polyarylate resin; a polystyrene resin; polyvinyl alcohol resins, and the like. Among them, the thermoplastic resin film is preferably a cyclic polyolefin resin film, a cellulose ester resin film, a polyester resin film or a (meth) acrylic resin film.

From the viewpoint of thickness reduction, the thickness of the thermoplastic resin film is usually 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, still more preferably 40 μm or less, still more preferably 30 μm or less, and further usually 5 μm or more, preferably 10 μm or more.

A hard coat layer may be formed on the thermoplastic resin film. The hard coat layer may be formed on one side or both sides of the thermoplastic resin film. By providing the hard coat layer, a thermoplastic resin film having improved hardness and scratch resistance can be produced.

The hard coat layer is, for example, a cured layer of an active energy ray-curable resin, preferably an ultraviolet ray-curable resin. Examples of the ultraviolet curable resin include (meth) acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. To increase strength, the hard coating layer may contain additives. The additive is not particularly limited, and examples thereof include inorganic fine particles, organic fine particles, and a mixture thereof.

The polymerizable liquid crystal compound used for forming the linear polarizer as the liquid crystal cured layer is a compound having a polymerizable reactive group and exhibiting liquid crystallinity. The polymerizable reactive group is a group participating in polymerization reaction, and is preferably a photopolymerizable reactive group. The photopolymerizable reactive group means a group capable of participating in polymerization reaction by a living radical, an acid, or the like generated by a photopolymerization initiator. Examples of the photopolymerizable reactive group include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloyloxy, methacryloyloxy, oxiranyl, and oxetanyl groups. Among them, acryloyloxy, methacryloyloxy, ethyleneoxy, ethyleneoxide, and oxetanyl groups are preferable, and acryloyloxy is more preferable. The type of the polymerizable liquid crystal compound is not particularly limited, and a rod-like liquid crystal compound, a discotic liquid crystal compound, and a mixture thereof may be used. The liquid crystallinity of the polymerizable liquid crystal compound may be either thermotropic liquid crystal or lyotropic liquid crystal, and if the thermotropic liquid crystal is classified into a nematic liquid crystal or a smectic liquid crystal according to the degree of order.

In the liquid crystal cured layer, the dichroic dye is dispersed in a cured product of the polymerizable liquid crystal compound and aligned. The dichroic dye used in the linear polarizer of the liquid crystal cured layer is preferably a dichroic dye having an absorption maximum wavelength in a range of 300nm to 700 nm. Examples of such a dichroic dye include an acridine dye, an oxazine dye, a cyanine dye, a naphthalene dye, an azo dye, and an anthraquinone dye, and among them, an azo dye is preferable. Examples of the azo dye include monoazo dye, disazo dye, trisazo dye, tetrazo dye, stilbene azo dye, and the like, and disazo dye and trisazo dye are preferable. The dichroic dye may be used alone or in combination of 2 or more, preferably 3 or more. In particular, it is more preferable to combine 3 or more azo compounds. A part of the dichroic dye may have a reactive group, or may have liquid crystallinity.

The linear polarizer as the liquid crystal cured layer can be formed by, for example, applying a composition for forming a linear polarizer containing a polymerizable liquid crystal compound and a dichroic dye to an alignment film formed on a base layer, and polymerizing and curing the polymerizable liquid crystal compound. The linear polarizer may be formed by applying a composition for forming a linear polarizer to a base layer to form a coating film, and stretching the coating film together with the base layer. The base material layer for forming the linear polarizer may be used as a protective film of the linear polarizer. The material and thickness of the base material layer may be the same as those of the thermoplastic resin film described above.

Examples of the composition for forming a linear polarizer containing a polymerizable liquid crystal compound and a dichroic dye, and a method for producing a linear polarizer using the composition include those described in Japanese patent application laid-open No. 2013-37353, japanese patent application laid-open No. 2013-33249, and Japanese patent application laid-open No. 2017-83843. The composition for forming a linear polarizer may further contain additives such as a solvent, a polymerization initiator, a crosslinking agent, a leveling agent, an antioxidant, a plasticizer, and a sensitizer, in addition to the polymerizable liquid crystal compound and the dichroic dye. These components may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The polymerization initiator that may be contained in the composition for forming a linear polarizer is a compound capable of initiating polymerization of a polymerizable liquid crystal compound, and a photopolymerization initiator is preferable from the viewpoint of initiating polymerization under a lower temperature condition. Specifically, a photopolymerization initiator capable of generating a living radical or an acid by the action of light is exemplified, and among them, a photopolymerization initiator capable of generating a radical by the action of light is preferable. The content of the polymerization initiator is preferably 1 part by mass or more and 10 parts by mass or less, more preferably 3 parts by mass or more and 8 parts by mass or less, relative to 100 parts by mass of the total amount of the polymerizable liquid crystal compound. If the amount is within this range, the reaction of the polymerizable group proceeds sufficiently, and the alignment state of the liquid crystal compound is easily stabilized.

The thickness of the linear polarizer as the liquid crystal cured layer is usually 10 μm or less, preferably 0.5 μm or more and 8 μm or less, more preferably 1 μm or more and 5 μm or less.

The optical laminate may include the above-described base material layer forming a linear polarizer as a liquid crystal cured layer. The base material layer may be the thermoplastic resin film or the protective film of the linear polarizer contained in the optically functional layer (a). Or the substrate layer may be peeled off from the linear polarizer. The optical laminate may or may not have the above-described alignment film.

The linear polarizer as the liquid crystal cured layer may have an overcoat layer on one or both sides thereof for the purpose of protecting the linear polarizer and the like. The overcoating layer may be formed, for example, by coating a composition for forming an overcoating layer on a linear polarizer. Examples of the material constituting the overcoat layer include a photocurable resin and a water-soluble polymer, and specifically, a (meth) acrylic resin, a polyvinyl alcohol resin, and the like can be used.

The visibility correction polarization degree Py of the linear polarizer is usually 95% or more, preferably 97% or more, more preferably 98% or more, still more preferably 98.7% or more, still more preferably 99.0% or more, particularly preferably 99.4% or more, and may be 99.9% or more. The visibility correction polarization degree Py of the linear polarizer may be 99.999% or less or 99.99% or less.

The visibility correction polarization degree Py can be calculated by correcting the visibility of the obtained polarization degree by using a spectrophotometer with an integrating sphere (V7100 manufactured by japan spectroscopy), using a 2-degree field of view (C light source) of "JIS Z8701".

Improving the visibility correction polarization Py of the linear polarizer is advantageous in improving the antireflection function of the optical laminate. If the visibility correction polarization degree Py is less than 95%, the antireflection function may not be exhibited.

The visibility-modifying monomer transmittance Ty of the linear polarizer is usually 41% or more, preferably 41.1% or more, more preferably 41.2% or more, and may be 42% or more, or may be 42.5% or more. The visibility-modifying monomer transmittance Ty of the linear polarizer is usually 50% or less, may be 48% or less, may be 46% or less, may be 44% or less, or may be 43% or less. If the visibility correction monomer transmittance Ty is too high, the visibility correction polarization Py becomes too low, and the antireflection function of the optical laminate may become insufficient.

The visibility correction monomer transmittance Ty can be calculated by correcting the obtained transmittance by visibility using a 2-degree field of view (C light source) of "JIS Z8701" using a spectrophotometer with an integrating sphere (V7100 manufactured by japan spectroscope).

The orthogonal color tone a of the linear polarizer is preferably in the range of-5 to 5, more preferably in the range of-3 to 3. The orthogonal color 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. The chromaticity a and b in the CIE color system were calculated for the obtained transmittance using an isochromatic function of a C light source using a spectrophotometer with integrating sphere (V7100 manufactured by japan spectroscopy), thereby obtaining a hue (monomer hue) of a single linear polarizer, a hue (parallel hue) of a parallel linear polarizer, and a hue (orthogonal hue) of a perpendicular linear polarizer.

(3) Phase difference layer

The optical laminate includes a retardation layer 3 having a1 st retardation layer 3 a. The linear polarizer 2 and the 1 st retardation layer 3a may be laminated via the 2 nd lamination layer 20. When a protective film is laminated on the side of the linear polarizer 2 opposite to the viewing side, the protective film and the 1 st retardation layer 3a may be laminated via the 2 nd lamination layer 20.

The retardation layer 3 may have only the 1 st retardation layer 3a, or may have a laminated structure of 2 or more retardation layers. That is, the retardation layer 3 may include 1 or more retardation layers different from the 1 st retardation layer 3 a. The retardation layer 3 may have an overcoat layer for protecting the surface thereof, a base material layer for supporting the retardation layer 3, and the like.

The 1 st retardation layer 3a is, for example, a lambda/4 layer. When the retardation layer 3 includes 2 retardation layers, examples of the combination of the retardation layers include a combination of λ/4 layer and λ/4 layer, a combination of λ/2 layer and λ/4 layer, and a combination of λ/4 layer and λ/2 layer, in this order from the linear polarizing plate 2 side. As the lamination of the retardation layers, a lamination layer (5 th lamination layer) described later can be used.

The in-plane phase difference Re (550) at the wavelength 550nm of the lambda/4 layer is usually in the range of 90nm to 220nm, preferably in the range of 100nm to 200 nm. The in-plane phase difference value Re (550) of the lambda/2 layer at a wavelength of 550nm is preferably in a range of 100nm to 300nm, more preferably 150nm to 300nm, still more preferably 200nm to 300 nm. The phase difference Rth (550) in the thickness direction of the positive C layer at a wavelength of 550nm is usually in the range of-170 nm to-10 nm, preferably in the range of-150 nm to-20 nm.

The retardation layer 3 has inverse wavelength dispersion, and the wavelength dispersion α is preferably 0.80 or more and 0.88 or less. This can effectively suppress the internal reflection.

The wavelength dispersion α refers to the ratio of the in-plane phase difference value Re (450) at the wavelength of 450nm to the in-plane phase difference value Re (550) at the wavelength of 550 nm.

The 1 st retardation layer 3a and the other retardation layers may be retardation films formed by stretching the thermoplastic resin film or may be liquid crystal cured layers. The liquid crystal cured layer is a cured product layer obtained by polymerizing and curing a polymerizable liquid crystal compound in an aligned state. The retardation layer 3 may include 1 or more cured layers of liquid crystal, or may include 2 or more layers.

Examples of the polymerizable liquid crystal compound include a rod-shaped polymerizable liquid crystal compound and a disk-shaped polymerizable liquid crystal compound, and one of them may be used, or a mixture containing both of them may be used. When the rod-shaped polymerizable liquid crystal compound is oriented horizontally or vertically with respect to the base material layer, the optical axis of the polymerizable liquid crystal compound coincides with the long axis direction of the polymerizable liquid crystal compound. When the disk-shaped polymerizable liquid crystal compound is aligned, the optical axis of the polymerizable liquid crystal compound is present in a direction perpendicular to the disk surface of the polymerizable liquid crystal compound.

In order to cause the liquid crystal cured layer formed by polymerizing the polymerizable liquid crystal compound to exhibit an in-plane retardation, the polymerizable liquid crystal compound may be aligned in an appropriate direction. When the polymerizable liquid crystal compound is rod-shaped, the optical axis of the polymerizable liquid crystal compound is aligned horizontally with respect to the plane of the base material layer, whereby an in-plane retardation is exhibited, and in this case, the optical axis direction coincides with the slow axis direction. When the polymerizable liquid crystal compound has a discotic shape, the optical axis of the polymerizable liquid crystal compound is aligned horizontally with respect to the plane of the base material layer, whereby an in-plane retardation is exhibited, and in this case, the optical axis is orthogonal to the slow axis. The alignment state of the polymerizable liquid crystal compound can be adjusted by a combination of the alignment layer and the polymerizable liquid crystal compound.

The polymerizable liquid crystal compound is a compound having at least 1 polymerizable reactive group and having liquid crystallinity. In the case of using 2 or more polymerizable liquid crystal compounds in combination, at least 1 type having 2 or more polymerizable reactive groups in the molecule is preferable. The polymerizable reactive group is a group participating in polymerization reaction, and is preferably a photopolymerizable reactive group. The photopolymerizable reactive group means a group capable of participating in polymerization reaction by a living radical, an acid, or the like generated by a photopolymerization initiator. Examples of the photopolymerizable reactive group are the same as described above. The liquid crystallinity of the polymerizable liquid crystal compound may be either thermotropic liquid crystal or lyotropic liquid crystal, or nematic liquid crystal or smectic liquid crystal if the thermotropic liquid crystal is classified into the order.

The optical stack may include an alignment layer adjacent to the phase difference layer. The alignment layer has an alignment regulating force for aligning the polymerizable liquid crystal compound in a desired direction. The alignment layer may be a vertical alignment layer that aligns the molecular axis of the polymerizable liquid crystal compound vertically with respect to the base material layer, a horizontal alignment layer that aligns the molecular axis of the polymerizable liquid crystal compound horizontally with respect to the base material layer, or an oblique alignment layer that aligns the molecular axis of the polymerizable liquid crystal compound obliquely with respect to the base material layer.

The thickness of the liquid crystal cured layer may be 0.1 μm or more, or 0.5 μm or more, or 1 μm or more, or 2 μm or more, and preferably 10 μm or less, or 8 μm or less, or 5 μm or less.

The liquid crystal cured layer may be formed by applying a composition for forming a liquid crystal layer containing a polymerizable liquid crystal compound onto a base layer, and drying the composition to polymerize the polymerizable liquid crystal compound. The composition for forming a liquid crystal layer may be coated on an alignment layer formed on a substrate layer. The material and thickness of the base material layer may be the same as those of the thermoplastic resin film described above. The base material layer may be assembled to the optical laminate together with the retardation layer as the liquid crystal cured layer, or the base material layer may be peeled off to assemble only the liquid crystal cured layer, or the liquid crystal cured layer and the alignment layer to the optical laminate.

(4) Adhesive layer

Fig. 2 is a schematic cross-sectional view showing another example of the optical laminate of the present invention. The optical laminate shown in fig. 2 includes an optical functional layer (a) 1, a1 st bonding layer 10, a linear polarizer 2, a2 nd bonding layer 20, a retardation layer 3 having inverse wavelength dispersion, and an adhesive layer 50. The pressure-sensitive adhesive layer 50 may be laminated on the surface of the optical laminate opposite to the observation side (optical functional layer (a) 1 side), and may be used for bonding the optical laminate to an image display element such as an organic EL display element.

In the optical laminate shown in fig. 2, the optical functional layer (a) 1 includes, in order from the observation side, a high refractive index layer 1a, a base material film 1b, a3 rd lamination layer 30, and a thermoplastic resin film 11. On the opposite side of the linear polarizer 2 to the viewing side, a protective film 12 is laminated via a4 th lamination layer 40. The 3 rd lamination layer 30 and the thermoplastic resin film 11 may be omitted. The 4 th adhesive layer 40 and the protective film 12 may be omitted.

In the optical laminate shown in fig. 2, the retardation layer 3 includes a1 st retardation layer 3a and a2 nd retardation layer 3b. The 1 st retardation layer 3a and the 2 nd retardation layer 3b are bonded by the 5 th bonding layer 3 c. However, the 5 th lamination layer 3c and the 2 nd retardation layer 3b may be omitted.

The thickness of the pressure-sensitive adhesive layer 50 may be, for example, 250 μm or less, and is preferably 100 μm or less, more preferably 50 μm or less, and still more preferably 40 μm or less from the viewpoint of thickness reduction. The lower limit of the thickness of the pressure-sensitive adhesive layer may be, for example, 1 μm or more, preferably 5 μm or more, and more preferably 10 μm or more from the viewpoint of durability.

The adhesive layer 50 may be composed of an adhesive composition containing a (meth) acrylic resin, a rubber resin, a urethane resin, an ester resin, a silicone resin, and a polyvinyl ether resin as a main component. Among them, an adhesive composition based on a (meth) acrylic resin excellent in transparency, weather resistance, heat resistance and the like is preferable. The adhesive composition may be an active energy ray-curable or a thermosetting type.

As the (meth) acrylic resin (base polymer) used in the adhesive composition, a polymer or copolymer containing 1 or 2 or more monomers among (meth) acrylic esters such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate is suitably used. The polar monomer is preferably copolymerized with the base polymer. Examples of the polar monomer include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, and the like, such as (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, acrylamide, N-dimethylaminoethyl (meth) acrylate, and glycidyl (meth) acrylate.

The adhesive composition may comprise only the above base polymer, but usually also contains a crosslinking agent. Examples of the crosslinking agent include a metal ion having a valence of 2 or more and forming a metal salt of a carboxylic acid with a carboxyl group, a polyamine compound forming an amide bond with a carboxyl group, a polyepoxide compound or a polyol forming an ester bond with a carboxyl group, and a polyisocyanate compound forming an amide bond with a carboxyl group. Among them, polyisocyanate compounds are preferable.

The adhesive layer 50 may contain a light selective absorber. The light selective absorber has a maximum absorption wavelength in a short wavelength region of visible light, that is, a wavelength region of 390 to 430nm, for example. Here, in the present embodiment, the "visible light" is light having a wavelength included in a range of 390nm to 830 nm. Examples of such a light selective absorber include salicylate-based compounds, benzophenone-based compounds, benzotriazole-based compounds, cyanoacrylate-based compounds, triazine-based compounds, and nickel complex-based compounds.

In addition, a compound having a maximum absorption wavelength in a wavelength region of 390 to 430nm can be synthesized by a known method and used as a light selective absorber. Examples of such pigments include compounds known as light selective absorbing compounds described in JP-A2017-120430.

The adhesive layer 50 may be an adhesive layer satisfying the following formula (1).

A(410)≥0.1 (1)

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

The larger the value of A (410) is, the higher the light absorption at the wavelength of 410nm is. If the value of A (410) is less than 0.1, the light absorption at the wavelength of 410nm is low, and deterioration of the organic EL display element and the retardation layer as the liquid crystal cured layer is liable to occur due to light in the vicinity of 400 nm. The value of a (410) is preferably 0.3 or more, more preferably 0.8 or more, and particularly preferably 1.0 or more. The upper limit is not particularly limited, and is usually 10 or less.

As described above, in the case where the adhesive layer 50 contains a light selective absorber and has light selective absorption property, the reflection tone is close to black display (the reflection tone of the circularly polarizing plate is made neutral), and thus slight light leakage is easily observed. Therefore, the optical laminate of the present invention which has the optical functional layer (a) and is capable of making light leakage less visible is also advantageous in the case of containing a layer having light selective absorption properties. The light absorbing performance may be imparted not only to the adhesive layer but also to the resin layer, the hard coat layer, the adhesive layer, and the like. The light selective absorber may be contained in a resin layer, a hard coat layer, a bonding layer, or the like.

The active energy ray-curable adhesive composition has a property of being cured by irradiation with active energy rays such as ultraviolet rays and electron beams, and has a property of having adhesiveness to an adherend such as a film even before irradiation with active energy rays and being cured by irradiation with active energy rays, thereby being capable of adjusting an adhesive force. The active energy ray-curable adhesive composition is preferably an ultraviolet ray-curable adhesive composition. The active energy ray-curable adhesive composition contains an active energy ray-polymerizable compound in addition to the base polymer and the crosslinking agent. A photopolymerization initiator, a photosensitizing agent, and the like may be contained as necessary.

(5) Diaphragm

As shown in fig. 3, the optical laminate may be provided with a separator 60 for protecting the outer surface of the adhesive layer 50 (the surface opposite to the 2 nd retardation layer 3 b). The optical laminate shown in fig. 3 has the same layer configuration as the optical laminate shown in fig. 2 except that the separator 60 is provided. The separator 60 is generally composed of a thermoplastic resin film having one surface subjected to a release treatment with a release agent such as a silicone-based or fluorine-based release agent, and the release treated surface thereof is bonded to the pressure-sensitive adhesive layer 50.

The thermoplastic resin constituting the separator 60 is, for example, polyethylene resin such as polyethylene, polypropylene resin such as polypropylene, polyester resin such as polyethylene terephthalate and polyethylene naphthalate, or the like. The thickness of the separator 60 is, for example, 10 μm or more and 50 μm or less.

(6) Protective film

As shown in fig. 4, the optical laminate may include a protective film 70 laminated on the surface of the optical functional layer (a) 1 side. The optical laminate shown in fig. 4 has the same layer configuration as the optical laminate shown in fig. 3, except that it has a protective film 70. The protective film 70 is composed of, for example, a base film and an adhesive layer laminated thereon. The above description is cited as the adhesive layer. The resin constituting the base film may be, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate and polyethylene naphthalate, or a thermoplastic resin such as a polycarbonate resin. Polyester resins such as polyethylene terephthalate are preferable.

(7) Front panel

As shown in fig. 5, the optical functional layer (a) 1 may further include a front panel 90. The front panel 90 is typically disposed on the outermost surface of the viewing side of the optical stack. The front panel 90 may be laminated on the viewing side surface of the high refractive index layer 1a via, for example, the 6 th adhesive layer 80. In this case, the optical functional layer (a) 1 includes the 6 th adhesive 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 that the 6 th adhesive layer 80 and the front panel 90 are provided.

The material and thickness of the front panel 90 are not limited as long as it is a plate-like body capable of transmitting light. The front panel 90 may be composed of only 1 layer or 2 or more layers. The front panel 90 may be a resin plate-like body (e.g., a resin plate, a resin sheet, a resin film, etc.), a glass plate-like body (e.g., a glass plate, a glass film, etc.), or a laminate of a resin plate-like body and a glass plate-like body. The front panel may constitute an outermost surface of the display device.

The thickness of the front panel 90 is, for example, 1000 μm or less, preferably 800 μm or less. The thickness is usually 10 μm or more, preferably 20 μm or more.

Examples of the resin constituting the resin plate-like body include thermoplastic resins such as triacetylcellulose, acetylcellulose butyrate, ethylene-vinyl acetate copolymer, propionylcellulose, butyrylcellulose, levulinyl cellulose, polyester, polystyrene, polyamide, polyetherimide, poly (meth) acrylic resin, polyimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and polyamideimide. These thermoplastic resins may be used alone or in combination of 2 or more. The resin plate-like body is preferably a thermoplastic resin film made of polyimide, polyamide, polyamideimide or the like from the viewpoint of improving strength and transparency.

From the viewpoint of hardness, the front panel 90 may be a thermoplastic resin film having a hard coat layer. The hard coat layer may be formed on one side or both sides of the thermoplastic resin film. By providing the hard coat layer, hardness and scratch resistance can be improved. The above description of the hard coat layer that can be formed on the thermoplastic resin film is cited as the hard coat layer.

In the case where the front panel 90 is a glass plate, the glass plate is preferably reinforced glass for display. The thickness of the glass plate may be, for example, 10 μm or more and 1000 μm or less, or 10 μm or more and 800 μm or less. By using a glass plate, a front panel having excellent mechanical strength and surface hardness can be constituted.

The front panel 90 preferably has high rigidity, and for example, has a young's modulus of 70GPa or more, or may have a young's modulus of 80GPa or more. The Young's modulus of the front panel 90 is generally 100GPa or less. Young's modulus can be determined as follows. A sample for measurement of the front panel 60 having a long side of 110mm and a short side of 10mm was cut out using a super cutter. Next, both ends of the measurement sample in the longitudinal direction were held by upper and lower clamps of a tensile tester (Autograph AG-Xplus tester manufactured by shimadzu corporation) so that the interval between the clamps became 5cm, and the measurement sample was stretched in the longitudinal direction at a stretching speed of 4 mm/min under an environment of a temperature of 23 ℃ and a relative humidity of 55%, whereby young's modulus at a temperature of 23 ℃ and a relative humidity of 55% was calculated from the slope of a straight line between 20 to 40MPa in the obtained stress-strain curve.

When the optical functional layer (a) 1 includes the front panel 90 laminated on the observation side surface of the high refractive index layer 1a via the 6 th adhesive layer 80, the refractive index of the 6 th adhesive layer 80 at the wavelength 550nm 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 the wavelength 550nm is preferably 1.49 or more and 1.52 or less, more preferably 1.50 or more and 1.52 or less, from the viewpoint that light leakage is less likely to be observed. The 6 th lamination layer 80 is preferably an adhesive layer.

When the optical laminate is applied to an image display device, the front panel 90 may have not only a function of protecting the front surface (screen) of the image display device (a function as a window film) but also a function as a touch sensor, a blue light cut-off function, a viewing angle adjustment function, and the like.

(8) Bonding layer

The optical stack may include a bonding layer for bonding 2 layers (or films). Examples of the lamination layer include a 1 st lamination layer 10 for laminating the optical functional layer (a) 1 and the linear polarizer 2, a 2 nd lamination layer 20 for laminating the linear polarizer 2 (or the protective film 12) and the retardation layer 3, a3 rd lamination layer 30 for laminating the base film 1b and the thermoplastic resin film 11, a 4 th lamination layer 40 for laminating the linear polarizer 2 and the protective film 12, a 5 th lamination layer 3c for laminating the 1 st retardation layer 3a and the 2 nd retardation layer 3b, a 6 th lamination layer 80 for laminating the front panel 90, and the like.

The adhesive layer is an adhesive layer made of an adhesive composition or an adhesive layer made of an adhesive composition. The adhesive composition and the adhesive layer described in (4) above are cited.

Examples of the adhesive composition include an aqueous adhesive and an active energy ray-curable adhesive. Examples of the aqueous adhesive include an aqueous polyvinyl alcohol resin solution and an aqueous two-component urethane emulsion adhesive. The active energy ray-curable adhesive is an adhesive cured by irradiation with active energy rays such as ultraviolet rays, and examples thereof include adhesives containing a polymerizable compound and a photopolymerization initiator, adhesives containing a photoreactive resin, adhesives containing a binder resin and a photoreactive crosslinking agent, and the like. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable (meth) acrylic monomers and photocurable urethane monomers, and oligomers derived from these monomers. The photopolymerization initiator may be a compound containing an active species such as a neutral radical, an anionic radical, or a cationic radical generated by irradiation with an active energy ray such as ultraviolet rays.

The thickness of the adhesive layer formed 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, and may be 100 μm or less, 50 μm or less, 25 μm or less, 15 μm or less, or 5 μm or less.

The two opposed surfaces bonded by the bonding layer may be subjected to surface activation treatment such as corona treatment, plasma treatment, flame treatment, or the like in advance.

< Image display device >)

The image display device of the present invention includes the optical laminate of the present invention and an image display element (an organic EL display element or the like). The optical layered body is disposed on the observation side of the image display element. The optical laminate may be attached to the image display element using the adhesive layer 50.

Fig. 6 is a schematic cross-sectional view showing an example of the image display device of the present invention. In fig. 6, as an example of the optical laminate, the optical laminate shown in fig. 5 is used. The optical laminate is bonded to the image display element 100 using the adhesive layer 50. A front panel 90 is laminated on the surface (outermost surface on the observation side) of the optical laminate opposite to the adhesive layer 50 via a 6 th lamination layer 80.

The image display device is not particularly limited, and examples thereof include an organic electroluminescence (organic EL) display device, an inorganic electroluminescence (inorganic EL) display device, a liquid crystal display device, an electroluminescence display device, and the like.

The image display device can be used as mobile devices such as smart phones and tablet computers, televisions, digital photo frames, electronic billboards, measuring instruments or metering instruments, office equipment, medical equipment, electric computing equipment and the like.

Examples

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

[ Measurement ]

(1) Reflectivity of optical functional layer

The reflectance R (450) and the reflectance R (550) of the optical functional layer were measured using "Cm2600d" manufactured by konikama midada. In measurement, a black acrylic plate (KANASE LITE, manufactured by KANASE, inc.) was bonded to the surface of the optical functional layer opposite to the surface on which light was incident via an adhesive layer.

(2) Refractive index and optical film thickness

The refractive index of the films and layers at a wavelength of 550nm was determined as follows. The reflectance in the visible light range was measured using a spectrophotometer "MPC-2200" manufactured by Shimadzu corporation. In the measurement, a black acrylic plate (KANASE LITE 1410 manufactured by KANASE, inc.) was bonded to the back surface of the measurement surface via an adhesive layer. The obtained reflectance spectrum was subjected to spectrum fitting so that the reflectance of the spectrum calculated from the calculation formula of the thin film interference spectrum, particularly at 550nm, was matched, and the refractive index and the optical film thickness at 550nm were calculated. However, regarding the laminate B-1, the refractive index and the optical film thickness at the wavelength of 550nm of the high refractive index layer were measured by the following methods.

(3) Phase difference characteristics of the phase difference layer

The retardation characteristics of the retardation layer were measured using "KOBRA-WPR" from Takara Shuzo Co., ltd.

In the present examples and comparative examples, the optical functional layers in the optical laminates obtained from the laminates A-1 to A-5, B-1 and B-2 are hereinafter referred to as optical functional layers A-1 'to A-5', B-1 'and B-2', respectively.

Production example 1: fabrication of optical functional layer

(1) Preparation of composition for Forming high refractive index layer

In each of the following examples, a composition for forming a high refractive index layer was prepared by the following procedure, respectively.

A photopolymerization initiator (Irgacure 184 manufactured by BASF corporation) and a dilution solvent (methyl ethyl ketone/propylene glycol monomethyl ether acetate mass ratio=5/1) were mixed and stirred. To this, an ultraviolet-curable resin ("KAYARAD-DPHA" manufactured by japan chemical company) was added and stirred. A zirconia particle dispersion ("ZRMIBK WT% -P03", manufactured by CIK-Nano Tek Co., ltd., solid content 15% by mass) was added and stirred to prepare a composition for forming a high refractive index layer.

(2) Production of laminates A-1 to A-5

A composition for forming a high refractive index layer was applied to a triacetylcellulose film (refractive index 1.49 at wavelength 550nm, hereinafter also referred to as "TAC film") having a thickness of 40 μm as a base film by using a bar coater, and the resultant film was dried and irradiated with ultraviolet rays, thereby producing a laminate a-1 composed of the base film and the high refractive index layer having an optical film thickness shown in table 1. The high refractive index layer forming compositions were coated on the TAC films, dried, and irradiated with ultraviolet rays, to prepare laminates a-2 to a-5. The refractive index of the high refractive index layer at 550nm and the optical film thickness are shown in Table 1.

(3) Production of optical functional layers A-1' -A-5

On the surface of the laminate A-1 opposite to the high refractive index layer (i.e., the surface on the substrate film side), a cyclic polyolefin resin film (HC-COP) with a hard coat layer was laminated via an adhesive layer (refractive index 1.47 at wavelength 550 nm) [ in-plane phase difference Re at wavelength 590 nm: 100nm, thickness of hc layer: 3 μm. Further, an adhesive layer (refractive index 1.47 at wavelength 550nm, haze 0.2%) was laminated on the high refractive index layer of the laminate a-1. An alkali-free glass plate (refractive index 1.51 at 550 nm) was bonded to the pressure-sensitive adhesive layer to obtain an optical functional layer A-1' composed of a glass plate, a pressure-sensitive adhesive layer, a high refractive index layer, a base film, a pressure-sensitive adhesive layer, and HC-COP.

An optically functional layer A-2' was obtained in the same manner as described above, except that the laminate A-2 was used.

An optically functional layer A-3' was obtained in the same manner as described above, except that the laminate A-3 was used.

An optically functional layer A-4' was obtained in the same manner as described above, except that the laminate A-4 was used.

An optically functional layer A-5' was obtained in the same manner as described above, except that the laminate A-5 was used.

(4) Production of optical functional layers A-2 'to A-5'

An annular polyolefin resin film (HC-COP) with a Hard Coat (HC) layer was laminated via an adhesive layer (refractive index 1.47 at wavelength 550 nm) on the side of the laminate A-2 opposite to the high refractive index layer (i.e., the side of the substrate film), to obtain an optical functional layer A-2 composed of the high refractive index layer/substrate film/adhesive layer/HC-COP.

An optical functional layer A-3 was obtained in the same manner as described above, except that the laminate A-3 was used.

An optical functional layer A-4 "was obtained in the same manner as described above, except that the laminate A-4 was used.

An optical functional layer A-5 "was obtained in the same manner as described above, except that the laminate A-5 was used.

(5) Production of optical functional layer B-1

As laminate B-1, "TECHNOLLOY C000" (polycarbonate resin film, overall thickness: 75 μm) (which is a single layer film, for convenience, referred to as laminate B-1) manufactured by Sumika acrylic Co., ltd.) was used. The refractive index of laminate B-1 at 550nm and the optical film thickness are shown in Table 1. The optical film thickness was measured using a contact thickness meter. The refractive index was measured in accordance with JIS K7142.

On one side of the laminate B-1, a hard-coated cyclic polyolefin resin film (HC-COP) was laminated via an adhesive layer (refractive index 1.47 at wavelength 550 nm), to obtain an optical functional layer B-1 composed of laminate B-1/adhesive layer/HC-COP.

(6) Production of optical functional layer B-2'

A laminate B-2 comprising a base film and a high refractive index layer having an optical film thickness shown in table 1 was produced by applying the composition for forming a high refractive index layer to a TAC film (refractive index 1.49 at wavelength 550 nm) having a thickness of 40 μm as a base film using a bar coater, drying the film, and irradiating the film with ultraviolet rays. The refractive index of the high refractive index layer at 550nm and the optical film thickness are shown in Table 1.

On one side of the laminate B-2, a hard-coated cyclic polyolefin resin film (HC-COP) was laminated via an adhesive layer (refractive index 1.47 at wavelength 550 nm), to obtain an optical functional layer B-2 composed of laminate B-2/adhesive layer/HC-COP.

TABLE 1

The reflectances R (450), R (550), and R (630), and the reflectance ratios (reflectance R (450)/R (550)) of the respective optical functional layers are shown in table 2.

TABLE 2

Production example 2: production of Linear polarization plate

(1) Production of Linear polarizer

A polyvinyl alcohol resin film having a thickness of 20 μm (average polymerization degree: about 2400, saponification degree: 99.9 mol% or more) was uniaxially stretched to about 5 times by dry stretching, immersed in pure water at a temperature of 60℃for 1 minute while maintaining the stretched state, and then immersed in an aqueous solution at a temperature of 28℃for 60 seconds at a mass ratio of iodine/potassium iodide/water of 0.05/5/100. Then, the mixture was immersed in an aqueous solution having a mass ratio of potassium iodide/boric acid/water of 8.5/8.5/100 and a temperature of 72℃for 300 seconds. Then, the film was washed with pure water at 26℃for 20 seconds, and then dried at 65℃to obtain a linear polarizer having a thickness of 8. Mu.m, in which iodine was adsorbed and oriented on the polyvinyl alcohol resin film. The obtained linear polarizer had a visibility-correcting monomer transmittance Ty of 42.5%, a visibility-correcting polarization Py of 99.99%, an orthogonal hue a of 0.1 and an orthogonal hue b of-0.3.

(2) Preparation of aqueous adhesive

An aqueous polyvinyl alcohol solution was prepared by dissolving 3 parts by mass of carboxyl-modified polyvinyl alcohol (KL-318 manufactured by Kuraray, inc.) in 100 parts by mass of water. To the obtained aqueous solution, a water-soluble polyamide epoxy resin (Sumirez Resin650,650 (30) manufactured by the chemical industry, cycloaka) was mixed in an amount of 1.5 parts by mass relative to 100 parts by mass of water, to obtain an aqueous adhesive.

(3) Production of Linear polarizing plate

The above-mentioned aqueous adhesive was applied to one surface of the above-mentioned obtained linear polarizer, a cyclic polyolefin resin film (HC-COP) with a Hard Coat (HC) layer was laminated, the above-mentioned obtained aqueous adhesive was applied to the other surface of the linear polarizer, a TAC film was laminated, and drying was performed at 80 ℃ for 5 minutes, thereby obtaining a linear polarizer having protective films on both surfaces of the linear polarizer. The layer structure of the linear polarizer is HC-COP/water-based adhesive layer/linear polarizer/water-based adhesive layer/TAC film. A protective film having an adhesive layer on a base film was laminated on an HC layer of a linear polarizing plate, to obtain a linear polarizing plate with a protective film (hereinafter, also referred to as a "linear polarizing plate with PF").

In the present linear polarizing plate, the reflectance of the aqueous adhesive layer was not measured as a significant value.

Production example 3: fabrication of phase-difference layer laminate

(1) Fabrication of 1 st phase-difference layer

An alignment layer was formed on a1 st base layer containing a transparent resin, and a1 st retardation layer containing a rod-like nematic polymerizable liquid crystal compound was coated with a1 st retardation layer-forming composition to prepare a1 st retardation layer with the 1 st base layer. The 1 st phase difference layer is lambda/4 layer. The thickness of the 1 st retardation layer was 2. Mu.m. The wavelength dispersion α of the 1 st retardation layer [ in-plane retardation value Re (450)/in-plane retardation value Re (550) ] was 0.85, and Re (550) was 142nm (average value at 12 in-plane).

In addition, the 1 st retardation layer was cut into 140mm×70mm, and the in-plane 12-point measurement of the in-plane retardation value of the 1 st retardation layer was performed. The deviation of the in-plane phase difference Re (550) was measured and calculated, and as a result, the maximum was 143nm and the minimum was 141nm. The difference between the maximum and minimum is 2nm. The production of the 1 st retardation layer will be described in detail below.

[ Preparation of composition (X) for Forming alignment layer ]

The light-oriented material (weight average molecular weight: 50000, m: n=50:50) having the following structure was produced according to the method described in japanese patent application laid-open No. 2021-196514. The composition (X) for forming an alignment layer was prepared by mixing 2 parts by mass of a photo-alignment material and 98 parts by mass of cyclopentanone (solvent) as components, and stirring the resultant mixture at 80 ℃ for 1 hour.

Light-oriented material:

[ chemical formula 1]

[ Production of nematic polymerizable liquid Crystal Compound ]

The polymerizable liquid crystal compound (A1) and the polymerizable liquid crystal compound (A2) each having the structures shown below were prepared. The polymerizable liquid crystal compound (A1) was prepared in the same manner as described in Japanese patent application laid-open No. 2019-003177. The polymerizable liquid crystal compound (A2) is prepared in the same manner as described in japanese patent application laid-open No. 2009-173893.

Polymerizable liquid crystal compound (A1):

[ chemical formula 2]

Polymerizable liquid crystal compound (A2):

[ chemical formula 3]

1Mg of the polymerizable liquid crystal compound (A1) was dissolved in 10mL of chloroform to obtain a solution. The obtained solution was added to a measurement cuvette having an optical path length of 1cm as a measurement sample, and the measurement sample was set in an ultraviolet-visible spectrophotometer (manufactured by Shimadzu corporation, "UV-2450"), to measure an absorption spectrum. The wavelength at which the absorbance became maximum was read from the obtained absorption spectrum, and as a result, the maximum absorption wavelength λmax was 356nm in the range of 300 to 400 nm.

[ Preparation of composition (Y) for Forming phase-difference layer ]

The polymerizable liquid crystal compound (A1) and the polymerizable liquid crystal compound (A2) were mixed in a mass ratio of 93:7, mixing to obtain a mixture. To 100 parts by mass of the resultant mixture, 0.1 part by mass of a leveling agent "BYK-361N" (manufactured by BM Chemie Co., ltd.) and 3 parts by mass of "Irgacure OXE-03" (manufactured by BASF Japan Co., ltd.) as a photopolymerization initiator were added. Further, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration became 13 mass%. The mixture was stirred at a temperature of 80℃for 1 hour, thereby preparing a composition (Y) for forming a1 st retardation layer.

[ Production of the 1 st phase-difference layer ]

The composition (X) for forming an alignment layer was applied to a biaxially stretched polyethylene terephthalate (PET) film (diaface mitsubishi resin co.) as the 1 st base layer by a bar coater. The obtained coating film was dried at 120℃for 2 minutes, and then cooled to room temperature to form a dried film. Then, an alignment layer was obtained by irradiating polarized ultraviolet light (100 mJ (313 nm standard) with a UV irradiation device (SPOTCURE SP-9; manufactured by USHIO Motor Co., ltd.). The thickness of the alignment layer was 100nm as measured by ellipsometer M-220 manufactured by Nippon spectroscopic Co.

The composition (Y) for forming the 1 st retardation layer was applied onto the obtained alignment layer by a bar coater to form a coating film. The coated film was dried by heating at 120℃for 2 minutes, and then cooled to room temperature, to obtain a dried film. Next, the above-mentioned dry film was irradiated with ultraviolet light having an exposure of 500mJ/cm ² (365 nm basis) under a nitrogen atmosphere using a high-pressure mercury lamp (usaio motor corporation "Unicure VB-15201 BY-a"), whereby a1 st retardation layer having a1 st substrate layer was formed BY curing a polymerizable liquid crystal compound in a state of being oriented in a horizontal direction with respect to the substrate surface, and a1 st retardation layer having a1 st substrate layer was obtained which was composed of a1 st substrate layer/an alignment layer/a 1 st retardation layer (a horizontally-oriented liquid crystal cured film). The 1 st retardation layer was measured to have a film thickness of 2.0 μm by using a laser microscope LEXT OLS4100 manufactured by olympus corporation.

(2) Production of the 2 nd phase-difference layer

The 2 nd retardation layer with the 2 nd base material layer was produced by the following method.

[ Preparation of composition (Y2) for Forming phase-difference layer ]

100 Parts by mass of a polymerizable liquid crystal compound Paliocolor LC242 (manufactured by BASF Japan Co., ltd.) and 0.1 part by mass of a leveling agent "BYK-361N" (manufactured by BYK-Chemie Co., ltd.) were mixed with 2.5 parts by mass of a photopolymerization initiator "Omnirad907" (manufactured by IGM Resin B.V. Co.). Further, 400 parts by mass of propylene glycol 1-monomethyl ether 2-acetate (PGME) was added, and the resultant mixture was stirred at a temperature of 80 ℃ for 1 hour, thereby preparing a composition (Y2) for forming a 2 nd retardation layer.

Polymerizable liquid crystal compound LC242:

[ chemical formula 4]

[ Preparation of composition (X2) for Forming alignment layer ]

To SUNEVER SE-610 (commercially available from Nissan chemical Co., ltd.) as an alignment polymer, 2-butoxyethanol was added so that the solid content became 1% by mass, to obtain an alignment layer-forming composition (X2).

[ Production of the 2 nd phase-difference layer ]

As the 2 nd base layer, cycloolefin polymer (COP) (ZF 14, manufactured by ZEON Co., ltd.) was used, one surface thereof was subjected to corona treatment using a corona treatment device (AGF-B10; manufactured by spring motor Co., ltd.), and the composition (X2) for forming an alignment layer was applied to the surface thereof using a bar coater and dried at 90℃for 1 minute. The film thickness of the obtained alignment layer was measured by a laser microscope and found to be 30nm. Next, the composition (Y2) for forming the 2 nd retardation layer was applied onto the alignment layer BY using a bar coater, dried at 90 ℃ for 1 minute, and then irradiated with ultraviolet light having an exposure of 1000mJ/cm ² (365 nm basis) under a nitrogen atmosphere using a high-pressure mercury lamp (usaio motor company "Unicure VB-15201 BY-a"), thereby obtaining a2 nd retardation layer with a2 nd base layer. As a result of measuring the film thickness by a laser microscope, the film thickness of the 2 nd retardation layer was 450nm. The in-plane phase difference value was measured using KOBRA-WR manufactured by prince measuring instruments Co. As a result, re (550) =1 nm and Rth (550) = -75nm. Thus, the 2 nd retardation layer with the 2 nd base material layer has optical characteristics shown by nx≡ny < nz. Since the phase difference value at the wavelength of 550nm of COP is approximately 0, the optical characteristics are not affected.

(3) Preparation of ultraviolet-curable adhesive

The following cationic curable components were mixed to prepare an ultraviolet curable adhesive.

3, 4-Epoxycyclohexane carboxylic acid 3',4' -epoxycyclohexyl methyl ester (trade name: CEL2021P, manufactured by Daicel Co., ltd.): 70 parts by mass

Neopentyl glycol diglycidyl ether (trade name: EX-211,Nagase ChemteX, manufactured by k.a.): 20 parts by mass

2-Ethylhexyl glycidyl ether (trade name: EX-121,Nagase ChemteX Co., ltd.): 10 parts by mass

Cationic polymerization initiator (trade name: CPI-100, 50% solution, manufactured by San-Apro Co., ltd.): 4.5 parts by mass (substantially solid component 2.25 parts by mass)

1, 4-Diethoxynaphthalene: 2.0 parts by mass

(4) Fabrication of phase-difference layer laminate

Corona treatment was performed on the retardation layer side of the 1 st retardation layer with the 1 st base material layer and the retardation layer side of the 2 nd retardation layer with the 2 nd base material layer, respectively. The prepared ultraviolet curable adhesive was applied to one corona treated surface, and the 1 st retardation layer with the 1 st base layer and the 2 nd retardation layer with the 2 nd base layer were bonded. The ultraviolet-curable adhesive is cured by irradiation of ultraviolet rays from the 2 nd substrate layer side, thereby forming an adhesive layer. The thickness of the ultraviolet-curable adhesive layer after curing was 1.5. Mu.m.

Example 1 >

(1) Fabrication of optical laminate

An adhesive layer (a (410) =1.10 and a thickness of 15 μm) containing a light selective absorber was bonded to the TAC film side surface of the linear polarizing plate obtained in production example 2. Next, the 1 st base layer of the retardation laminate obtained in production example 3 was peeled off and the above-mentioned linear polarizing plate was laminated on the exposed alignment layer so that the adhesive layer containing the light selective absorber was in contact.

Next, the laminate a-1 was laminated on the HC layer of the linear polarizing plate via an adhesive layer (storage modulus: 25500Pa, refractive index at 550nm of 1.47, haze of 0.2%, containing no light selective absorber) so as to be in contact with the TAC film side. Further, an adhesive layer (storage modulus: 25500Pa, refractive index at 550nm of 1.47, haze of 0.2%, and no light selective absorber) was laminated on the high refractive index layer of the laminate A-1. An alkali-free glass plate (refractive index 1.51 at 550 nm) was bonded to the adhesive layer to obtain an optical laminate including an optical functional layer a-1'.

(2) Measurement and evaluation of reflection Properties

The reflectance Y and the reflection hues a and b of the optical laminate obtained in (1) above were measured using "Cm2600d" manufactured by konikama americada. The results are shown in Table 4. In measurement, a glass plate (thickness: 0.7mm, EAGLE XG manufactured by Corning) was bonded to the surface of the optical laminate opposite to the surface of the incident light (surface of the optical laminate opposite to the optically functional layer) via an adhesive layer (storage modulus: 25500Pa, refractive index at wavelength of 550 nm: 1.47, haze: 0.2%, and no light selective absorber). The optical laminate with glass plate obtained as described above was placed on a reflecting plate (reflectance: 96% or more and diffuse reflectance: 9% or less) with the optical functional layer facing upward, and was measured in a state where the layer structure was a reflecting plate/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.

A: the reflectance Y is less than 6.0%.

B: the reflectance Y is 6.0% or more.

(3) Determination and evaluation of light leakage

The 2 nd base layer was peeled off from the optical laminate obtained in the above (1), and an aluminum foil (a "collar thickness 50" of an aluminum foil manufactured by UACJ, a thickness of 20 μm) as a reflecting plate was laminated on the exposed surface side thereof. The state of slight light leakage was visually observed from a place spaced 30cm upward from the observation side (the side opposite to the aluminum foil) of the optical laminate under a fluorescent lamp, and evaluated according to the following criteria. The results are shown in Table 4.

A: no light leakage was observed.

B: light leakage was observed.

Examples 2, 3, 5, 6 >

Optical laminates each including optical functional layers A-2', A-3', A-4', A-5' were produced in the same manner as in example 1, except that laminates A-2, A-3, A-4, and A-5 were used instead of laminate A-1, respectively, and reflection characteristics and light leakage were measured and evaluated. The results are shown in Table 4.

Example 4 >

Next, on the HC layer of the linear polarizing plate, the laminate a-3 was laminated via an adhesive layer (storage modulus: 25500Pa, refractive index at 550nm, haze 0.2%, no light selective absorber) so as to be in contact with the TAC film side, to obtain an optical laminate including an optical functional layer a-3 ".

Example 7, 8 >

Optical laminates each including optical functional layers a-4 "and a-2" were produced in the same manner as in example 4, except that laminates a-4 and a-2 were used instead of laminate a-3, respectively, and reflection characteristics and light leakage were measured and evaluated. The results are shown in Table 4.

Comparative example 1 >

An adhesive layer (a (410) =1.10 and a thickness of 15 μm) containing a light selective absorber was bonded to the TAC film side surface of the linear polarizing plate obtained in production example 2. Next, the 1 st base layer of the retardation laminate obtained in production example 3 was peeled off and the above-mentioned linear polarizing plate was laminated on the exposed alignment layer so that the adhesive layer containing the light selective absorber was in contact therewith, and an optical laminate was produced, and reflection characteristics and light leakage were measured and evaluated in the same manner as in example 1. The results are shown in Table 4.

Comparative example 2 >

An alkali-free glass plate (refractive index 1.51 at 550 nm) was laminated on a linear polarizing plate of the optical laminate of comparative example 1 via an adhesive layer (storage modulus: 25500Pa, refractive index 1.47 at 550nm, haze 0.2%, and no light selective absorber), to prepare an optical laminate, and reflection characteristics and light leakage were measured and evaluated in the same manner as in example 1. The results are shown in Table 4.

The following partial laminated structures included in the optical laminated bodies of comparative examples 1 and 2 were measured for reflectance R (450), reflectance R (550) and reflectance R (630), and reflectance ratio (reflectance R (450)/reflectance R (550)), and the results are shown in table 3.

Comparative example 1: HC-COP

Comparative example 2: glass plate/adhesive layer/HC-COP

TABLE 3

Comparative examples 3 to 5

Optical laminates each including optical functional layers B-1", B-2", and a-5 "were produced in the same manner as in example 4, except that laminates B-1, B-2, and a-5 were used instead of laminate a-3, respectively, and reflection characteristics and light leakage were measured and evaluated. The results are shown in Table 4.

TABLE 4

Description of the reference numerals

1: Optical functional layer (a), 1a: high refractive index layer, 1b: substrate film, 2: linear polarizer, 3: phase difference layer, 3a: 1 st phase difference layer, 3b: 2 nd retardation layer, 3c: lamination layer 5, 10: lamination layer 1, 11: thermoplastic resin film, 12: protective film, 20: lamination layer 2, 30: lamination layer 3, 40: lamination layer 4, 50: adhesive layer, 60: a diaphragm, 70: protective film, 80: lamination layer 6, 90: front panel, 100: an image display element.

Claims

1. An optical laminate comprising, in order, an optical functional layer A, a linear polarizer and a retardation layer having inverse wavelength dispersion,

Ratio of reflectance R (450) at wavelength 450nm to reflectance R (550) at wavelength 550nm of the optical functional layer a: r (450)/R (550) is 1.07 or more and 1.55 or less,

The reflectivity R (550) is less than 6.0%.

2. The optical laminate according to claim 1, wherein the optical functional layer a comprises a high refractive index layer having a refractive index of 1.6 or more at a wavelength of 550 nm.

3. The optical laminate according to claim 2, wherein the optical functional layer a comprises a base film and the high refractive index layer laminated on the base film.

4. The optical stack according to claim 1, wherein the ratio of the reflectivity R (450) to the reflectivity R (550): r (450)/R (550) is 1.07 or more and 1.35 or less.

5. The optical laminate according to claim 1, wherein the retardation layer comprises 1 or more cured layers of liquid crystal.

6. The optical laminate according to claim 1, wherein the optical functional layer a further comprises a front panel.

7. The optical laminate according to claim 1, further comprising an adhesive layer disposed on an opposite side of the retardation layer from the linear polarizer.

8. The optical laminate according to claim 7, further comprising a separator disposed on an opposite side of the adhesive layer from the phase difference layer.

9. The optical laminate according to claim 1, further comprising a protective film on a surface of the optical functional layer a opposite to the linear polarizer.

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