OPTICAL LAYERED BODY

- NITTO DENKO CORPORATION

Provided is an optical laminate having the following feature: when the optical laminate is used in an image display apparatus, the optical laminate can express a sufficient brightness, can express a satisfactory hue, and can achieve a cost reduction while suppressing a reflectance. The optical laminate of the present invention includes: a wavelength conversion layer; and an absorption layer arranged on one side of the wavelength conversion layer, wherein the absorption layer has an absorption peak in a wavelength band in a range of from 580 nm to 610 nm, and wherein the absorption layer contains a compound x represented by the general formula (I) or the general formula (II).

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Description
TECHNICAL FIELD

The present invention relates to an optical laminate.

BACKGROUND ART

In recent years, an image display apparatus including a light-emitting layer including a light-emitting material, such as quantum dots, has been attracting attention as an image display apparatus excellent in color reproducibility (e.g., Patent Literature 1). For example, when light enters a quantum dot film using quantum dots, the quantum dots are excited to emit fluorescence. For example, when the backlight of a blue LED is used, part of blue light is converted into red light and green light by the quantum dot film, and another part of the blue light is output as it is as blue light. As a result, white light can be achieved. Further, the use of such quantum dot film is said to be capable of achieving a color reproducibility of 100% or more in terms of NTSC ratio.

Such image display apparatus as described above has a high reflectance. In view of the foregoing, a polarizing plate is generally used in such image display apparatus as described above for reducing the reflectance.

However, the use of the polarizing plate involves a problem, such as a reduction in brightness of the apparatus, an abnormal hue thereof, or an increase in cost thereof. Accordingly, a brightness improvement, a hue improvement, and a cost reduction have been required in such image display apparatus as described above.

CITATION LIST Patent Literature

[PTL 1] JP 2015-111518 A

SUMMARY OF INVENTION Technical Problem

The present invention has been made to solve the conventional problems, and a primary object of the present invention is to provide an optical laminate having the following feature: when the optical laminate is used in an image display apparatus, the optical laminate can express a sufficient brightness, can express a satisfactory hue, and can achieve a cost reduction while suppressing a reflectance.

Solution to Problem

According to one embodiment of the present invention, there is provided an optical laminate, including: a wavelength conversion layer; and an absorption layer arranged on one side of the wavelength conversion layer, wherein the absorption layer has an absorption peak in a wavelength band in a range of from 580 nm to 610 nm, and wherein the absorption layer contains a compound X represented by the following general formula (I) or general formula (II).

in the formula (I),

R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),

R1 and R2 form a saturated cyclic skeleton including 5 or 6 carbon atoms, and R3, R4, R5, R6, R7, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),

R2 and R3 form a saturated cyclic skeleton including 5 to 7 carbon atoms, and R1, R4, R5, R6, R7, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),

R5 and R6 form a saturated cyclic skeleton including 5 or 6 carbon atoms, and R1, R2, R3, R4, R7, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),

R6 and R7 form a saturated cyclic skeleton including 5 to 7 carbon atoms, and R1, R2, R3, R4, R5, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),

R1 and R2 form a saturated cyclic skeleton including 5 or 6 carbon atoms, R5 and R6 form a saturated cyclic skeleton including 5 or 6 carbon atoms, and R3, R4, R7, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b), or

R2 and R3 form a saturated cyclic skeleton including 5 to 7 carbon atoms, R6 and R7 form a saturated cyclic skeleton including 5 to 7 carbon atoms, and R1, R4, R5, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b); and

in the formula (II), R4 and R8 each independently represent a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms.

In one embodiment, the optical laminate is free of a polarizing plate on a side of the absorption layer opposite to the wavelength conversion layer.

In one embodiment, the wavelength conversion layer contains quantum dots or a phosphor as a wavelength conversion material.

In one embodiment, the wavelength conversion layer is a color filter.

According to another embodiment of the present invention, there is provided an image display apparatus. The image display apparatus includes the optical laminate.

In one embodiment, the image display apparatus includes a liquid crystal panel including the optical laminate, and a backlight.

In one embodiment, the liquid crystal panel includes the absorption layer, the wavelength conversion layer, a viewer-side polarizing plate, a liquid crystal cell, and a backlight-side polarizing plate in the stated order from a viewer side.

Advantageous Effects of Invention

According to the present invention, the optical laminate having the following feature can be provided: when the optical laminate is used in an image display apparatus, the optical laminate can express a sufficient brightness, can express a satisfactory hue, and can achieve a cost reduction while suppressing a reflectance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view of an optical laminate according to one embodiment of the present invention.

FIG. 2 is a schematic sectional view of one embodiment of an image display apparatus including the optical laminate of the present invention.

FIG. 3 is a schematic sectional view of an optical laminate according to one embodiment of the present invention.

FIG. 4 is a schematic sectional view of one embodiment of an image display apparatus including the optical laminate of the present invention.

 DESCRIPTION OF EMBODIMENTS

Now, preferred embodiments of the present invention are described. However, the present invention is not limited to these embodiments.

<<<<Optical Laminate>>>>

FIG. 1 is a schematic sectional view of an optical laminate according to one embodiment of the present invention. An optical laminate 100 of this embodiment includes a wavelength conversion layer 10 and an absorption layer 20 arranged on one side of the wavelength conversion layer 10. In one embodiment, the optical laminate 100 is arranged on the viewer side of an image display apparatus so that the absorption layer 20 maybe on the viewer side.

The wavelength conversion layer is a layer configured to convert the wavelength of part of incident light to emit light.

The absorption layer contains a specific coloring matter to be described later (coloring matter represented by the general formula (I) or (II)). When the absorption layer is formed so as to contain such specific coloring matter, an optical laminate having the following feature can be provided: when the optical laminate is used in an image display apparatus, the optical laminate can express a sufficient brightness, can express a satisfactory hue, and can achieve a cost reduction while suppressing a reflectance.

In one embodiment, the optical laminate is free of a polarizing plate on the side of the absorption layer opposite to the wavelength conversion layer. Even when the optical laminate of the present invention does not include any polarizing plate, the optical laminate can express a sufficient brightness and can express a satisfactory hue while suppressing a reflectance. In addition, the exclusion of a polarizing plate can prevent a brightness reduction and achieve a cost reduction. Further, the mechanical characteristics of the absorption layer can be adjusted with a high degree of freedom, and hence, for example, such design that a function as a hard coat layer is imparted to the layer in addition to a reflection-reducing function is possible. Such a mode that “the optical laminate is free of a polarizing plate on the side of the absorption layer opposite to the wavelength conversion layer” as used herein includes such a mode that the optical laminate is free of a polarizer at the site, and such a mode that the optical laminate is free of a circularly polarizing plate at the site.

The thickness of the optical laminate of the present invention is preferably from 10 μm to 1,000 μm, more preferably from 15 μm to 800 μm, still more preferably from 20 μm to 600 μm, particularly preferably from 20 μm to 500 μm.

The total light reflectance of the optical laminate (a measurement method therefor is described in detail later) is preferably 60% or less, more preferably 50% or less, still more preferably 40% or less, particularly preferably 35% or less, most preferably 30% or less. The lower limit value of the total light reflectance of the optical laminate, which is desirably as small as possible, is, for example, 5%.

In the present invention, a Δab based on the reflection hue (a*, b*) of the optical laminate (a measurement method therefor is described in detail later) with respect to a D65 light source is preferably 8 or less, more preferably 7 or less, still more preferably 6 or less. The lower limit value of the Δab is desirably as small as possible, and is ideally 0. When the Δab of the optical laminate of the present invention falls within the ranges, the optical laminate can express a more satisfactory hue in the case of being used in an image display apparatus. The Δab is determined from the equation “Δab=(a*2+b*2)1/2”.

The optical laminate of the present invention may include any appropriate other layer to the extent that the effect of the present invention is not impaired.

The optical laminate of the present invention may include a protective film. Specifically, the optical laminate of the present invention may include the protective film on, for example, the side of the absorption layer opposite to the wavelength conversion layer.

The optical laminate of the present invention may include a refractive index-adjusting layer. Specifically, the optical laminate of the present invention may include the refractive index-adjusting layer on, for example, the side of the absorption layer opposite to the wavelength conversion layer.

<<Wavelength Conversion Layer>>

The wavelength conversion layer typically contains a wavelength conversion material. More specifically, the wavelength conversion layer may contain a matrix and a wavelength conversion material dispersed in the matrix.

The wavelength conversion layer may be adopted as, for example, a color filter.

The wavelength conversion layer may be a single layer, or may have a laminated structure. When the wavelength conversion layer has a laminated structure, its respective layers may typically contain wavelength conversion materials having different light emission characteristics.

The thickness of the wavelength conversion layer (when the layer has a laminated structure, its total thickness) is preferably from 1 μm to 500 μm, more preferably from 100 μm to 400 μm. When the thickness of the wavelength conversion layer falls within such ranges, an optical laminate excellent in conversion efficiency and durability can be obtained. When the wavelength conversion layer has a laminated structure, the thickness of each of its layers is preferably from 1 μm to 300 μm, more preferably from 10 μm to 250 μm.

<Matrix>

Any appropriate material maybe used as a material for forming the matrix (hereinafter sometimes referred to as “matrix material”) to the extent that the effect of the present invention is not impaired. Examples of such material include a resin, an organic oxide, and an inorganic oxide. It is preferred that the matrix material have low oxygen permeability and low moisture permeability, have high light stability and high chemical stability, have a predetermined refractive index, have excellent transparency, and/or have excellent dispersibility for the wavelength conversion material. The matrix may practically include a resin film or a pressure-sensitive adhesive.

(Resin Film)

When the matrix is a resin film, any appropriate resin may be used as a resin for forming the resin film to the extent that the effect of the present invention is not impaired. Specifically, the resin may be a thermoplastic resin, maybe a thermosetting resin, or may be an active energy ray-curable resin. Examples of the active energy ray-curable resin include an electron beam-curable resin, a UV-curable resin, and a visible light-curable resin.

When the matrix is a resin film, specific examples of the resin for forming the resin film include epoxy, (meth)acrylates (e.g., methyl methacrylate and butyl acrylate), norbornene, polyethylene, poly(vinyl butyral), poly(vinyl acetate), polyurea, polyurethane, aminosilicone (AMS), polyphenylmethylsiloxane, polyphenylalkylsiloxanes, polydiphenylsiloxane, polydialkylsiloxanes, silsesquioxanes, silicone fluoride, vinyl and hydride-substituted silicones, styrene-based polymers (e.g., polystyrene, aminopolystyrene (APS), poly(acrylonitrile ethylene styrene) (AES)), polymers each cross-linked with a difunctional monomer (e.g., divinylbenzene), polyester-based polymers (e.g., polyethylene terephthalate), cellulose-based polymers (e.g., triacetyl cellulose), vinyl chloride-based polymers, amide-based polymers, imide-based polymers, vinyl alcohol-based polymers, epoxy-based polymers, silicone-based polymers, and acrylic urethane-based polymers. Those resins may be used alone or in combination thereof (e.g., blend or copolymer). After any one of those resins has been formed into a film, the film may be subjected to a treatment, such as stretching, heating, or pressurization. The resin is preferably a thermosetting resin or a UV-curable resin, more preferably a thermosetting resin.

(Pressure-Sensitive Adhesive)

When the matrix is a pressure-sensitive adhesive, any appropriate pressure-sensitive adhesive may be used as the pressure-sensitive adhesive to the extent that the effect of the present invention is not impaired. The pressure-sensitive adhesive preferably has transparency and optical isotropy. Specific examples of the pressure-sensitive adhesive include a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, an epoxy-based pressure-sensitive adhesive, and a cellulose-based pressure-sensitive adhesive. The pressure-sensitive adhesive is preferably a rubber-based pressure-sensitive adhesive or an acrylic pressure-sensitive adhesive.

<Wavelength Conversion Material>

The wavelength conversion material can control the wavelength conversion characteristic of the wavelength conversion layer. Examples of the wavelength conversion material include quantum dots and a phosphor. That is, the wavelength conversion layer preferably contains quantum dots or a phosphor as the wavelength conversion material.

The content of the wavelength conversion material in the wavelength conversion layer (when two or more kinds of materials are used, their total content) is preferably from 0.01 part by weight to 50 parts by weight, more preferably from 0.01 part by weight to 30 parts by weight with respect to 100 parts by weight of the matrix material (typically a resin or pressure-sensitive adhesive solid content). When the content of the wavelength conversion material falls within such ranges, an image display apparatus excellent in balance among all of R, G, and B hues can be achieved.

(Quantum Dots)

The center emission wavelength of each of the quantum dots may be adjusted by, for example, a material for the quantum dots, and/or the composition, particle size, or shape of each of the dots.

The quantum dots may each include any appropriate material to the extent that the effect of the present invention is not impaired. The quantum dots may each include preferably an inorganic material, more preferably an inorganic conductive material or an inorganic semiconductor material. Examples of the semiconductor material include Group II-VI, Group III-V, Group IV-VI, and Group IV semiconductors. Specific examples thereof include Si, Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP, BAs, AIN, Alp, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdSeZn, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si3N4, Ge3N4, Al2O3, (Al,Ga,In)2(S,Se,Te)3, and Al2CO. Those materials may be used alone or in combination thereof. The quantum dots may each contain a p-type dopant or an n-type dopant. The quantum dots may each have a core-shell structure. In such core-shell structure, any appropriate functional layer (a single layer or a plurality of layers) may be formed around a shell in accordance with a purpose, and the surface of the shell may be subjected to a surface treatment and/or chemical modification.

Any appropriate shape may be adopted as the shape of each of the quantum dots in accordance with a purpose. Specific examples of the shape of each of the quantum dots include a perfect spherical shape, a flaky shape, a plate shape, an elliptical spherical shape, and an indefinite shape.

Any appropriate size may be adopted as the size of the quantum dots in accordance with a desired emission wavelength. The size of the quantum dots is preferably from 1 nm to 10 nm, more preferably from 2 nm to 8 nm. When the size of the quantum dots falls within such ranges, green light emission and red light emission each become sharp, and hence a high color rendering property can be achieved. For example, green light may be emitted when the size of the quantum dots is about 7 nm, and red light may be emitted when the size is about 3 nm. For example, when the shape of each of the quantum dots is a perfect spherical shape, the size of the quantum dots is their average particle diameter, and when the shape is a shape except the perfect spherical shape, the size is a dimension along the minimum axis in the shape.

The quantum dots are described in detail in, for example, JP 2012-169271 A, JP 2015-102857 A, JP 2015-65158 A, JP 2013-544018 A, and JP 2010-533976 A, the descriptions of which are incorporated herein by reference. Commercial products may be used as the quantum dots.

(Phosphor)

Any appropriate phosphor capable of emitting light having a desired color maybe used as the phosphor in accordance with a purpose. Specific examples thereof include a red phosphor and a green phosphor.

The red phosphor is, for example, a composite fluoride phosphor activated with Mn4+. The composite fluoride phosphor refers to a coordination compound that contains at least one coordination center (e.g., M to be described later), that is surrounded with fluoride ions each acting as a ligand, and that is compensated with charge by a counterion (e.g., A to be described later) as required. Specific examples of such composite fluoride phosphor include A2[MF5]:Mn4+, A3[MF6]:Mn4+, Zn2[MF7]:Mn4+, A[In2F7]:Mn4+, A2[M′F6]:Mn4+, E[M′F6]:Mn4+, A3[ZrF7]:Mn4+, and Ba0.65Zr0.35F2.70:Mn4+. Herein, A represents Li, Na, K, Rb, Cs, NH4, or a combination thereof. M represents Al, Ga, In, or a combination thereof. M′ represents Ge, Si, Sn, Ti, Zr, or a combination thereof. E represents Mg, Ca, Sr, Ba, Zn, or a combination thereof. Such a composite fluoride phosphor that a coordination number in its coordination center is 6 is preferred. Details about such red phosphor are described in, for example, JP 2015-84327 A, the description of which is incorporated herein by reference in its entirety.

The green phosphor is, for example, a compound containing, as a main component, a solid solution of a sialon having a β-type Si3N4 crystal structure. A treatment for setting the amount of oxygen in such sialon crystal to a specific amount (e.g., 0.8 mass %) or less is preferably performed. The performance of such treatment can provide a green phosphor that emits sharp light having a narrow peak width. Details about such green phosphor are described in, for example, JP2013-28814A, the description of which is incorporated herein by reference in its entirety.

<<Absorption Layer>>

The absorption layer preferably contains any appropriate one or more kinds of coloring materials. In the absorption layer, the coloring material is typically present in a matrix.

As described above, the absorption layer has an absorption peak in the wavelength band in the range of from 580 nm to 610 nm. The formation of such absorption layer can improve the antireflection function of the optical laminate while suppressing a reduction in visible light transmittance (i.e., a reduction in brightness) thereof. In addition, when the wavelength of light to be absorbed by the layer is adjusted, a reflection hue can be made neutral, and hence an optical laminate reduced in coloring can be obtained. The absorption spectrum of the layer maybe measured with a spectrophotometer (manufactured by Hitachi High-Technologies Corporation, product name: “U-4100”).

The ratio (A545/Amax) of the absorbance A545 of the peak of the absorption layer at a wavelength of 545 nm to the absorbance Amax of the highest absorption peak of the absorption layer at a wavelength of from 580 nm to 610 nm is preferably 0.13 or less, more preferably 0.12 or less, still more preferably 0.11 or less, particularly preferably 0.1 or less. When an absorption layer having a small absorbance at a wavelength of 545 nm as described above is formed, an optical laminate that can contribute to the widening of the color gamut of an image display apparatus by absorbing light that is not needed for color representation can be obtained. In addition, the layer hardly absorbs light emitted from a light source whose wavelength is around 545 nm at which a visibility is high, and hence can be suppressed in brightness reduction.

In the absorption layer, the half width of the absorption peak in the wavelength range of from 580 nm to 610 nm is preferably 35 nm or less, more preferably 30 nm or less, still more preferably 25 nm or less, particularly preferably 20 nm or less. When the half width falls within such ranges, an optical laminate that can contribute to the widening of the color gamut of an image display apparatus can be obtained.

In one embodiment, the absorption layer is free of an absorption peak in the range of from 530 nm to 570 nm. More specifically, the absorption layer is free of an absorption peak having an absorbance of 0.1 or more in the range of from 530 nm to 570 nm. The formation of such absorption layer can provide an optical laminate that can contribute to the widening of the color gamut of an image display apparatus.

In one embodiment, the absorption layer further has an absorption peak in a wavelength band in the range of from 440 nm to 510 nm. That is, in this embodiment, the absorption layer has absorption peaks in the wavelength bands in the ranges of from 440 nm to 510 nm and from 580 nm to 610 nm. With such configuration, the color mixing of red light and green light, and that of green light and blue light can be satisfactorily prevented. When the optical laminate configured as described above is used as an antireflection film for an image display apparatus, the color gamut of the image display apparatus can be widened, and hence bright and vivid image quality can be obtained. An absorption layer having two or more absorption peaks as described above may be obtained by using a plurality of kinds of coloring materials.

The transmittance of the absorption layer at an absorption peak is preferably from 0% to 80%, more preferably from 0% to 70%. When the transmittance falls within such ranges, the above-mentioned effect of the present invention becomes more significant.

The visible light transmittance of the absorption layer is preferably from 30% to 90%, more preferably from 30% to 80%. When the visible light transmittance falls within such ranges, an optical laminate that can exhibit an antireflection function while being suppressed in brightness reduction can be obtained.

The haze value of the absorption layer is preferably 15% or less, more preferably 10% or less, still more preferably 5% or less. Although the haze value of the absorption layer is preferably as small as possible, its lower limit is, for example, 0.1%.

The thickness of the absorption layer is preferably from 1 μm to 100 μm, more preferably from 2 μm to 30 μm.

(Coloring Material)

In one embodiment, the absorption layer contains, as a coloring material, a compound X represented by the following general formula (I) or general formula (II). The compound X is a compound having an absorption peak in the wavelength band in the range of from 580 nm to 610 nm.

in the formula (I),

R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),

R1 and R2 form a saturated cyclic skeleton including 5 or 6 carbon atoms, and R3, R4, R5, R6, R7, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),

R2 and R3 form a saturated cyclic skeleton including 5 to 7 carbon atoms, and R1, R4, R5, R6, R7, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),

R5 and R6 form a saturated cyclic skeleton including 5 or 6 carbon atoms, and R1, R2, R3, R4, R7, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),

R6 and R7 form a saturated cyclic skeleton including 5 to 7 carbon atoms, and R1, R2, R3, R4, R5, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),

R1 and R2 form a saturated cyclic skeleton including 5 or 6 carbon atoms, R5 and R6 form a saturated cyclic skeleton including 5 or 6 carbon atoms, and R3, R4, R7, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b), or

R2 and R3 form a saturated cyclic skeleton including 5 to 7 carbon atoms, R6 and R7 form a saturated cyclic skeleton including 5 to 7 carbon atoms, and R1, R4, R5, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b); and

in the formula (II), R4 and R8 each independently represent a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms.

The saturated cyclic skeleton (number of carbon atoms: 5 or 6) formed so as to include R1 and R2, and the saturated cyclic skeleton (number of carbon atoms: 5 or 6) formed so as to include R5 and R6 may each have a substituent. The substituent is, for example, an alkyl group having 1 to 4 carbon atoms. In addition, the saturated cyclic skeleton (number of carbon atoms: 5 to 7) formed so as to include R2 and R3, and the saturated cyclic skeleton (number of carbon atoms: 5 to 7) formed so as to include R6 and R7 may each have a substituent. The substituent is, for example, an alkyl group having 1 to 4 carbon atoms.

In one embodiment, R4 and/or R8 has a benzene ring or a naphthalene ring as a substituent.

Specific examples of the compound X represented by the formula (I) or (II) include compounds represented by the following general formulae (I-1) to (I-27) and (II-1). The absorption peak of the compound X is shown in each of the following tables. With regard to each of the formulae (I-1) to (I-23), an absorption peak obtained by measuring the absorbance of a film formed of a resin composition prepared by mixing aliphatic polycarbonate with the compound X is shown, and with regard to each of the formulae (I-24) to (I-27) and (II-1), an absorption peak obtained by measuring the absorbance of a film formed of a resin composition prepared by mixing a polymethyl methacrylate resin with the compound X is shown.

Absorption peak NO. Compound X (nm) I-1 596 nm (APC) I-2 595 nm (APC) I-3 582 nm (APC) I-4 585 nm (APC) I-5 585 nm (APC) I-6 575 nm (APC) I-7 585 nm (APC) I-8 587 nm (APC) I-9 587 nm (APC) I-10 588 nm (APC) I-11 588 nm (APC) I-12 589 nm (APC) I-13 592 nm (APC) I-14 591 nm (APC) I-15 595 nm (APC) I-16 595 nm (APC) I-17 596 nm (APC) I-18 614 nm (APC) I-19 581 nm (APC) I-20 591 nm (APC) I-21 593 nm (APC) I-22 594 nm (APC) I-23 594 nm (APC) I-24 592 nm I-25 593 nm I-26 594 nm I-27 594 nm II-1 597 nm

The content of the compound X is preferably from 0.01 part by weight to 50 parts by weight, more preferably from 0.05 part by weight to 10 parts by weight, still more preferably from 0.1 part by weight to 5 parts by weight, particularly preferably from 0.1 part by weight to 1 part by weight with respect to 100 parts by weight of the matrix material.

The absorption layer may further contain a compound having an absorption peak in the wavelength band in the range of from 440 nm to 510 nm. For example, an anthraquinone-based, oxime-based, naphthoquinone-based, quinizarin-based, oxonol-based, azo-based, xanthene-based, or phthalocyanine-based compound (dye) is used as such compound.

The content of the compound having an absorption peak in the wavelength band in the range of from 440 nm to 510 nm is preferably from 0.01 part by weight to 50 parts by weight, more preferably from 0.01 part by weight to 25 parts by weight with respect to 100 parts by weight of the matrix material.

(Matrix)

The matrix may be a pressure-sensitive adhesive, or may be a resin film. The matrix is preferably a pressure-sensitive adhesive. In addition, the following may be performed: an absorption layer is formed by using the resin film, and the absorption layer is used as a functional layer, such as a hard coat layer (or as one component of the functional layer).

When the matrix is a pressure-sensitive adhesive, any appropriate pressure-sensitive adhesive may be used as the pressure-sensitive adhesive to the extent that the effect of the present invention is not impaired. The pressure-sensitive adhesive preferably has transparency and optical isotropy. Specific examples of the pressure-sensitive adhesive include a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, an epoxy-based pressure-sensitive adhesive, and a cellulose-based pressure-sensitive adhesive. The pressure-sensitive adhesive is preferably a rubber-based pressure-sensitive adhesive or an acrylic pressure-sensitive adhesive.

A rubber-based polymer serving as the rubber-based pressure-sensitive adhesive is a polymer showing rubber elasticity in a temperature region around room temperature. Preferred examples of the rubber-based polymer (A) include a styrene-based thermoplastic elastomer (A1), an isobutylene-based polymer (A2), and a combination thereof.

Examples of the styrene-based thermoplastic elastomer (A1) may include styrene-based block copolymers, such as a styrene-ethylene-butylene-styrene block copolymer (SEBS), a styrene-isoprene-styrene block copolymer (SIS), a styrene-butadiene-styrene block copolymer (SBS), a styrene-ethylene-propylene-styrene block copolymer (SEPS, a hydrogenated product of SIS), a styrene-ethylene-propylene block copolymer (SEP, a hydrogenated product of a styrene-isoprene block copolymer), a styrene-isobutylene-styrene block copolymer (SIBS), and a styrene-butadiene rubber (SBR). Of those, a styrene-ethylene-propylene-styrene block copolymer (SEPS, a hydrogenated product of SIS), a styrene-ethylene-butylene-styrene block copolymer (SEBS), and a styrene-isobutylene-styrene block copolymer (SIBS) are preferred because the copolymers each have polystyrene blocks at both ends of a molecule thereof and have a high cohesive force as a polymer. A commercial product may be used as the styrene-based thermoplastic elastomer (Al). Specific examples of the commercial product include SEPTON and HYBRAR manufactured by Kuraray Co., Ltd., Tuftec manufactured by Asahi Kasei Chemicals Corporation, and SIBSTAR manufactured by Kaneka Corporation.

The weight-average molecular weight of the styrene-based thermoplastic elastomer (A1) is preferably from about 50,000 to about 500,000, more preferably from about 50,000 to about 300,000, still more preferably from about 50,000 to about 250,000. The weight-average molecular weight of the styrene-based thermoplastic elastomer (A1) preferably falls within such ranges because both of the cohesive force and viscoelasticity of the polymer can be achieved.

A styrene content in the styrene-based thermoplastic elastomer (A1) is preferably from about 5 wt % to about 70 wt %, more preferably from about 5 wt % to about 40 wt %, still more preferably from about 10 wt % to about 20 wt %. The styrene content in the styrene-based thermoplastic elastomer (A1) preferably falls within such ranges because viscoelasticity based on a soft segment can be secured while a cohesive force based on a styrene moiety is maintained.

Examples of the isobutylene-based polymer (A2) may include polymers each including isobutylene as a constituent monomer and having a weight-average molecular weight (Mw) of preferably 500,000 or more. The isobutylene-based polymer (A2) may be a homopolymer of isobutylene (polyisobutylene, PIB) or may be a copolymer including isobutylene as a main monomer (i.e., a copolymer obtained by copolymerizing isobutylene at a ratio of more than 50 mol %). Examples of such copolymer may include a copolymer of isobutylene and normal butylene, a copolymer of isobutylene and isoprene (e.g., a butyl rubber, such as a regular butyl rubber, a chlorinated butyl rubber, a brominated butyl rubber, or a partially cross-linked butyl rubber), and vulcanized products and modified products thereof (e.g., a product modified with a functional group, such as a hydroxyl group, a carboxyl group, an amino group, or an epoxy group). Of those, polyisobutylene (PIB) is preferred because the polyisobutylene is free of a double bond in its main chain, and is excellent in weatherability. A commercial product may be used as the isobutylene-based polymer (A2). The commercial product is specifically, for example, OPPANOL manufactured by BASF.

The weight-average molecular weight (Mw) of the isobutylene-based polymer (A2) is preferably 500,000 or more, more preferably 600,000 or more, still more preferably 700,000 or more. In addition, the upper limit of the weight-average molecular weight (Mw) is preferably 5,000,000 or less, more preferably 3,000,000 or less, still more preferably 2,000,000 or less. When the weight-average molecular weight of the isobutylene-based polymer (A2) is set to 500,000 or more, a pressure-sensitive adhesive that is more excellent in durability at the time of its high-temperature storage can be obtained.

The content of the rubber-based polymer (A) in the pressure-sensitive adhesive is preferably 30 wt % or more, more preferably 40 wt % or more, still more preferably 50 wt % or more, particularly preferably 60 wt % or more in the total solid content of the pressure-sensitive adhesive. The upper limit of the content of the rubber-based polymer is preferably 95 wt % or less, more preferably 90 wt % or less.

In the rubber-based pressure-sensitive adhesive, the rubber-based polymer (A) and any other rubber-based polymer may be used in combination. Specific examples of the other rubber-based polymer include: a butyl rubber (IIR), a butadiene rubber (BR), an acrylonitrile-butadiene rubber (NBR), EPR (binary ethylene-propylene rubber), EPT (ternary ethylene-propylene rubber), an acrylic rubber, a urethane rubber, and a polyurethane-based thermoplastic elastomer; a polyester-based thermoplastic elastomer; and a blend-based thermoplastic elastomer, such as a polymer blend of polypropylene and EPT (ternary ethylene-propylene rubber). The compounding amount of the other rubber-based polymer is preferably about 10 parts by weight or less with respect to 100 parts by weight of the rubber-based polymer (A).

The acrylic polymer of the acrylic pressure-sensitive adhesive typically contains an alkyl (meth)acrylate as a main component, and may contain an aromatic ring-containing (meth)acrylate, an amide group-containing monomer, a carboxyl group-containing monomer, and/or a hydroxyl group-containing monomer as a copolymerization component in accordance with a purpose. The term “(meth)acrylate” as used herein means an acrylate and/or a methacrylate. The alkyl (meth)acrylate may be, for example, an alkyl (meth) acrylate having a linear or branched alkyl group having 1 to 18 carbon atoms. The aromatic ring-containing (meth)acrylate is a compound containing an aromatic ring structure in its structure and containing a (meth)acryloyl group. The aromatic ring is, for example, a benzene ring, a naphthalene ring, or a biphenyl ring. The aromatic ring-containing (meth)acrylate satisfies durability and can alleviate display unevenness due to a white void of the peripheral portion of an image display apparatus. The amide group-containing monomer is a compound containing an amide group in its structure and containing a polymerizable unsaturated double bond, such as a (meth) acryloyl group or a vinyl group. The carboxyl group-containing monomer is a compound containing a carboxyl group in its structure and containing a polymerizable unsaturated double bond, such as a (meth) acryloyl group or a vinyl group. The hydroxyl group-containing monomer is a compound containing a hydroxyl group in its structure and containing a polymerizable unsaturated double bond, such as a (meth) acryloyl group or a vinyl group. Details about the acrylic pressure-sensitive adhesive are described in, for example, JP 2015-199942 A, the description of which is incorporated herein by reference.

When the matrix is a resin film, any appropriate resin may be used as a resin for forming the resin film. Specifically, the resin may be a thermoplastic resin, may be a thermosetting resin, or may be an active energy ray-curable resin. Examples of the active energy ray-curable resin include an electron beam-curable resin, a UV-curable resin, and a visible light-curable resin.

When the matrix is a resin film, specific examples of the resin for forming the resin film include epoxy, (meth)acrylates (e.g., methyl methacrylate and butyl acrylate), norbornene, polyethylene, poly(vinyl butyral), poly(vinyl acetate), polyurea, polyurethane, aminosilicone (AMS), polyphenylmethylsiloxane, polyphenylalkylsiloxanes, polydiphenylsiloxane, polydialkylsiloxanes, silsesquioxanes, silicone fluoride, vinyl and hydride-substituted silicones, styrene-based polymers (e.g., polystyrene, aminopolystyrene (APS), poly(acrylonitrile ethylene styrene) (AES)), polymers each cross-linked with a difunctional monomer (e.g., divinylbenzene), polyester-based polymers (e.g., polyethylene terephthalate), cellulose-based polymers (e.g., triacetyl cellulose), vinyl chloride-based polymers, amide-based polymers, imide-based polymers, vinyl alcohol-based polymers, epoxy-based polymers, silicone-based polymers, and acrylic urethane-based polymers. Those resins may be used alone or in combination thereof (e.g., blend or copolymer). After any one of those resins has been formed into a film, the film may be subjected to a treatment, such as stretching, heating, or pressurization. The resin is preferably a thermosetting resin or a UV-curable resin, more preferably a thermosetting resin.

<<Protective Film>>

Any appropriate film may be used as the protective film. Specific examples of a material serving as a main component of such film include transparent resins, such as a cellulose-based resin, such as triacetyl cellulose (TAC), a (meth)acrylic resin, a polyester-based resin, a polyvinyl alcohol-based resin, a polycarbonate-based resin, a polyamide-based resin, a polyimide-based resin, a polyether sulfone-based resin, a polysulfone-based resin, a polystyrene-based resin, a polynorbornene-based resin, a polyolefin-based resin, and an acetate-based resin. In addition, the examples also include thermosetting resins or UV-curable resins, such as an acrylic resin, a urethane-based resin, an acrylic urethane-based resin, an epoxy-based resin, and a silicone-based resin. In addition to the foregoing, a glassy polymer, such as a siloxane-based polymer, is also given as an example. A polymer film described in JP 2001-343529 A (WO 01/37007 A1) may also be used. For example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in a side chain thereof, and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in side chains thereof maybe used as a material for the film, and the resin composition is, for example, a resin composition including: an alternating copolymer formed of isobutene and N-methylmaleimide; and an acrylonitrile-styrene copolymer. The polymer film may be, for example, an extrusion molded product of the resin composition. Any appropriate pressure-sensitive adhesive layer or adhesive layer is used in the lamination of a polarizer and the protective film. The pressure-sensitive adhesive layer is typically formed of an acrylic pressure-sensitive adhesive. The adhesive layer is typically formed of a polyvinyl alcohol-based adhesive.

<<Refractive Index-Adjusting Layer>>

The refractive index of the refractive index-adjusting layer is preferably 1.2 or less, more preferably 1.15 or less, still more preferably from 1.01 to 1.1. When the refractive index of the refractive index-adjusting layer falls within such ranges, the utilization efficiency of light output from the wavelength conversion layer can be improved, and ambient light reflection can be suppressed.

The refractive index-adjusting layer typically has a void therein. The void content of the refractive index-adjusting layer may adopt any appropriate value. The void content of the refractive index-adjusting layer is preferably from 5% to 99%, more preferably from 25% to 95%. When the void content of the refractive index-adjusting layer falls within such ranges, the refractive index of the refractive index-adjusting layer can be sufficiently reduced, and the layer can obtain high mechanical strength.

The refractive index-adjusting layer having a void therein maybe formed of, for example, a structure having at least one shape selected from a particulate shape, a fibrous shape, and a flat plate shape. A structure (constituent unit) for forming the particulate shape may be a solid particle or a hollow particle, and specific examples thereof include: silicone particles and silicone particles each having a fine pore; and silica hollow nanoparticles and silica hollow nanoballoons. A fibrous constituent unit is, for example, a nanofiber having a nanosized diameter, and specific examples thereof include cellulose nanofibers and alumina nanofibers. A flat plate-shaped constituent unit is, for example, nanoclay, and is specifically, for example, nanosized bentonite (e.g., KUNIPIA F (product name)).

Any appropriate material may be adopted as a material for forming the refractive index-adjusting layer. Materials described in, for example, WO 2004/113966 A1, JP 2013-254183 A, and JP 2012-189802 A may each be adopted as such material. Specific examples thereof include: silica-based compounds; hydrolyzable silanes, and partial hydrolysates and dehydration condensates thereof; organic polymers; silanol group-containing silicon compounds; active silicas each obtained by bringing a silicate into contact with an acid or an ion-exchange resin; polymerizable monomers (e.g., a (meth) acrylic monomer and a styrene-based monomer); curable resins (e.g., a (meth)acrylic resin, a fluorine-containing resin, and a urethane resin); and combinations thereof.

Examples of the organic polymer include polyolefins (e.g., polyethylene and polypropylene), polyurethanes, fluorine-containing polymers (e.g., a fluorine-containing copolymer having a fluorine-containing monomer unit and a constituent unit for imparting cross-linking reactivity as constituent components), polyesters (e.g., a poly(meth)acrylic acid derivative (the term “(meth)acrylic acid” as used herein means acrylic acid and methacrylic acid, and “(meth)” is used in such meaning in all cases)), polyethers, polyamides, polyimides, polyureas, and polycarbonates.

The material for forming the refractive index-adjusting layer preferably includes: silica-based compounds; and hydrolyzable silanes, and partial hydrolysates and dehydration condensates thereof.

Examples of the silica-based compound include: SiO2 (silicic anhydride) ; and compounds each containing SiO2 and at least one compound selected from the group consisting of Na2O—B2O3 (borosilicic acid), Al2O3 (alumina), B2O3, TiO2, ZrO2, SnO2, Ce2O3, P2O5, Sb2O3, MoO3, ZnO2, WO3, TiO2—Al2O3, TiO2—ZrO2, In2O3—SnO2, and Sb2O3—SnO2 (the symbol “—” indicates that the oxide is a composite oxide).

The hydrolyzable silanes are, for example, hydrolyzable silanes each containing an alkyl group that may have a substituent (e.g., fluorine). The hydrolyzable silanes, and the partial hydrolysates and dehydration condensates thereof are preferably an alkoxysilane and a silsesquioxane.

The alkoxysilane may be a monomer or an oligomer. The alkoxysilane monomer preferably has three or more alkoxyl groups. Examples of the alkoxysilane monomer include methyltrimethoxysilane, methyltriethoxysilane, phenyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetrapropoxysilane, diethoxydimethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane. The alkoxysilane oligomer is preferably a polycondensate obtained by subjecting the alkoxysilane monomer to hydrolysis and polycondensation. When the alkoxysilane is used as the material for forming the refractive index-adjusting layer, a refractive index-adjusting layer having excellent uniformity is obtained.

The silsesquioxane is a collective term of network-like polysiloxanes each represented by the general formula RSiO1.5 (provided that R represents an organic functional group). Examples of the organic functional group represented by R include an alkyl group (the group may be linear or branched, and has 1 to 6 carbon atoms), a phenyl group, and an alkoxy group (e.g., a methoxy group and an ethoxy group). The silsesquioxane has, for example, any one of a ladder-type structure and a cage-type structure. When the silsesquioxane is used as the above-mentioned material, a refractive index-adjusting layer having excellent uniformity, excellent weatherability, excellent transparency, and excellent hardness is obtained.

Any appropriate particles may be adopted as the above-mentioned particles. The particles are typically silica particles.

The shape of each of the silica particles may be identified through, for example, observation with a transmission electron microscope. The average particle diameter of the silica particles is preferably from 5 nm to 200 nm, more preferably from 10 nm to 200 nm. When the particles have such configuration, a refractive index-adjusting layer having a sufficiently low refractive index can be obtained, and the transparency of the refractive index-adjusting layer can be maintained. In this description, the average particle diameter means a value given from the specific surface area (m2/g) of the particles, which is measured by a nitrogen adsorption method (BET method),by the equation “average particle diameter=(2,720/specific surface area)” (see JP 01-317115 A).

Examples of a method of obtaining the refractive index-adjusting layer include methods described in JP 2010-189212 A, JP 2008-040171 A, JP 2006-011175 A, WO 2004/113966 A1, and references thereof. Specific examples thereof include: a method including subjecting at least one of a silica-based compound, and hydrolyzable silanes, and partial hydrolysates and dehydration condensates thereof to hydrolysis and polycondensation; a method including using porous particles and/or hollow fine particles; a method including producing an aerogel layer through the utilization of a springback phenomenon; and a method including using pulverized gel, which is obtained by pulverizing gel obtained through a sol-gel process and chemically bonding fine porous particles in the pulverization liquid with a catalyst or the like. However, the method of obtaining the refractive index-adjusting layer is not limited to the production methods, and the layer may be produced by any production method.

The refractive index-adjusting layer may be bonded to the wavelength conversion layer or the absorption layer via any appropriate adhesion layer (e.g., an adhesive layer or a pressure-sensitive adhesive layer: not shown). When the refractive index-adjusting layer includes a pressure-sensitive adhesive, the adhesion layer may be omitted.

The haze of the refractive index-adjusting layer is, for example, from 0.1% to 30%, preferably from 0.2% to 10%.

With regard to the mechanical strength of the refractive index-adjusting layer, for example, its scratch resistance against BEMCOT (trademark) is desirably from 60% to 100%.

An anchoring force between the refractive index-adjusting layer and the wavelength conversion layer or the absorption layer, which is not particularly limited, is preferably 0.01 N/25 mm or more, more preferably 0.1 N/25 mm or more, still more preferably 1 N/25 mm or more. To improve the mechanical strength or the anchoring force, the refractive index-adjusting layer may be subjected to an undercoating treatment, a heating treatment, a humidifying treatment, a UV treatment, a corona treatment, a plasma treatment, or the like in a step before or after the formation of its coating film, or before or after its bonding to any appropriate adhesion layer or any other member.

The thickness of the refractive index-adjusting layer is preferably from 100 nm to 5,000 nm, more preferably from 200 nm to 4,000 nm, still more preferably from 300 nm to 3,000 nm, particularly preferably from 500 nm to 2,000 nm. When the thickness falls within such ranges, a refractive index-adjusting layer, which expresses an optically sufficient function on light in a visible light region, and which has excellent durability, can be achieved.

<<<<Image Display Apparatus>>>>

FIG. 2 is a schematic sectional view of one embodiment of an image display apparatus including the optical laminate of the present invention. In FIG. 2, a case in which the image display apparatus is a liquid crystal display apparatus is illustrated as a typical example. A liquid crystal display apparatus 1000 includes a liquid crystal panel 200 and a backlight 300, and the optical laminate of the present invention may be a member for the liquid crystal panel 200. The wavelength conversion layer may be a color filter to be included in the liquid crystal panel 200.

In one embodiment, the optical laminate is an optical laminate including a wavelength conversion layer and an absorption layer, and is free of a polarizing plate on the side of the absorption layer opposite to the wavelength conversion layer. One embodiment of such optical laminate of the present invention includes the absorption layer 20, the wavelength conversion layer 10, and a polarizing plate 30 in the stated order as illustrated in, for example, FIG. 3. In FIG. 3, typically, the absorption layer 20 side is a viewer side, and the polarizing plate 30 side is a backlight side. Of course, FIG. 3 is merely one embodiment of the optical laminate of the present invention, and the optical laminate of the present invention is not limited to the embodiment illustrated in FIG. 3.

More specifically, the liquid crystal display apparatus 1000 may adopt, for example, such an embodiment as illustrated in FIG. 4. In FIG. 4, the liquid crystal display apparatus 1000 includes the liquid crystal panel 200 and the backlight 300, and the liquid crystal panel 200 includes the absorption layer 20, the wavelength conversion layer 10, a polarizing plate (viewer-side polarizing plate) 30a, a liquid crystal cell 40, and a polarizing plate (backlight-side polarizing plate) 30b in the stated order. In FIG. 4, the absorption layer 20 side is a viewer side, and the polarizing plate (backlight-side polarizing plate) 30b side is a backlight side. Of course, FIG. 4 is merely one embodiment of the image display apparatus including the optical laminate of the present invention, and the image display apparatus including the optical laminate of the present invention is not limited to the embodiment illustrated in FIG. 4.

A light source to be included in the backlight is, for example, a cold-cathode tube light source (CCFL) or a LED light source. In one embodiment, the backlight includes the LED light source. The use of the LED light source can provide an image display apparatus excellent in viewing angle characteristic. In one embodiment, a light source (preferably a LED light source) configured to emit blue light is used.

The backlight may be of a direct system, or may be of an edge light system.

The backlight may further include any other member, such as a light guide plate, a diffusion plate, or a prism sheet, in addition to the light source as required.

The liquid crystal panel typically includes the liquid crystal cell.

The liquid crystal cell includes a pair of substrates and a liquid crystal layer serving as a display medium, the layer being sandwiched between the substrates. Ina general configuration, a color filter (e.g., a wavelength conversion layer) and a black matrix are arranged on one substrate, and a switching element configured to control the electro-optical characteristics of the liquid crystal, a scan line configured to apply a gate signal to the switching element and a signal line configured to apply a source signal thereto, and a pixel electrode and a counter electrode are arranged on the other substrate. An interval (cell gap) between the substrates may be controlled with, for example, a spacer. For example, an alignment film formed of polyimide may be arranged on the side of each of the substrates in contact with the liquid crystal layer.

In one embodiment, the liquid crystal layer contains liquid crystal molecules aligned in homeotropic alignment under a state in which no electric field is present. Such liquid crystal layer (as a result, the liquid crystal cell) typically shows a three-dimensional refractive index of nz>nx=ny. A drive mode using the liquid crystal molecules aligned in homeotropic alignment under a state in which no electric field is present is, for example, a vertical alignment (VA) mode. The VA mode encompasses a multi-domain VA (MVA) mode.

In another embodiment, the liquid crystal layer contains liquid crystal molecules aligned in homogeneous alignment under a state in which no electric field is present. Such liquid crystal layer (as a result, the liquid crystal cell) typically shows a three-dimensional refractive index of nx>ny=nz. The relationship “ny=nz” as used herein encompasses not only a case in which the ny and the nz are completely equal to each other, but also a case in which the ny and the nz are substantially equal to each other. Typical examples of a drive mode using the liquid crystal layer that shows such three-dimensional refractive index include an in-plane switching (IPS) mode and a fringe field switching (FFS) mode. The above-mentioned IPS mode encompasses a super in-plane switching (S-IPS) mode or an advanced super in-plane switching (AS-IPS) mode, which adopts, for example, a V-shaped electrode or a zigzag electrode. In addition, the above-mentioned FFS mode encompasses an advanced fringe field switching (A-FFS) mode or an ultra fringe field switching (U-FFS) mode, which adopts, for example, a V-shaped electrode or a zigzag electrode. The symbol “nx” represents a refractive index in the direction in which a refractive index in a plane becomes maximum (i.e., a slow axis direction), the symbol “ny” represents a refractive index in the direction perpendicular to the slow axis in the plane (i.e., a fast axis direction), and the symbol “nz” represents a thickness direction refractive index.

EXAMPLES

Now, the present invention is specifically described by way of Examples. However, the present invention is by no means limited by these Examples. Methods of measuring the respective characteristics are as described below.

[Reflectance, Reflection Spectrum, and Reflection Hue (a*, b*)]

The total light reflectance, reflection spectrum, and reflection hue (a*, b*) of an optical laminate obtained in each of Example and Comparative Examples were measured with a spectrocolorimeter CM-2600d (light source: D65) manufactured by Konica Minolta, Inc. In the case of an optical laminate including a wavelength conversion layer and an absorption layer, a reflective plate (manufactured by Toray Advanced Film Co., Ltd., CERAPEEL DMS-X42) was bonded to a wavelength conversion layer side via an acrylic pressure-sensitive adhesive (thickness: 20 μm) produced with reference to JP 2549388 B2, and light was caused to enter from an absorption layer side.

[Δab]

A Δab was determined from the reflection hue (a*, b*) by using the equation “Δab=(a*2+b*2)1/2”.

[Front Brightness]

The optical laminate obtained in each of Example and Comparative Examples was arranged so that its wavelength conversion layer was on a light source side, and its brightness was measured with a brightness meter (manufactured by Konica Minolta, Inc., product name: “SR-UL1”) by using blue LED uniform light-emitting surface lighting (manufactured by Aitec System Co., Ltd.: model number: TMN150X180-22BD-4) as a light source. The luminous brightness of the uniform light-emitting surface lighting was 1, 335 cd/m2 in the case of the wavelength conversion layer alone.

Example 1 (Wavelength Conversion Layer)

A commercial television (manufactured by Samsung Electronics Co., Ltd., product name: “UN65JS9000FXZA”) was dismantled to provide a wavelength conversion material in its backlight side, that is, a quantum dot sheet. The quantum dot sheet was adopted as a wavelength conversion layer (1).

(Absorption Layer)

A coloring matter-containing pressure-sensitive adhesive containing 0.3 part by weight of a radical generator (benzoyl peroxide, manufactured by Nippon Oil & Fats Co., Ltd., product name: “NYPER BMT”), 1 part by weight of an isocyanate-based cross-linking agent (manufactured by Tosoh Corporation, product name: “CORONATE L”), 0.3 part by weight of a squaraine compound represented by the following general formula (I-20), and 0.2 part by weight of a phenol-based antioxidant (manufactured by BASF Japan Ltd., product name: “IRGANOX 1010”) with respect to 100 parts by weight of an acrylic polymer obtained by copolymerizing n-butyl acrylate and a hydroxy group-containing monomer was produced. The coloring matter-containing pressure-sensitive adhesive obtained in the foregoing was applied onto a PET substrate (manufactured by Mitsubishi Plastics, Inc., product name: “MRF38CK”), which had been subjected to a treatment for facilitating the peeling of the pressure-sensitive adhesive, with an applicator so as to have a thickness of 20 μm, and the adhesive was dried at 155° C. for 2 minutes. After that, the resultant was bonded to TAC (triacetyl cellulose film, manufactured by FUJIFILM Corporation). Thus, an absorption layer (1) (absorption maximum wavelength: 594 nm) was formed on the TAC.

The squaraine compound represented by the general formula (I-20) was synthesized by the following method.

<Synthesis of Squaraine Compound>

1-Phenyl-1,4,5,6-tetrahydrocyclopenta[b]pyrrole was synthesized by a method described in “M. Beller et. al., J. Am. Chem. Soc., 2013, 135(30), 11384-11388”.

300 Milligrams of 1-phenyl-1,4,5,6-tetrahydrocyclopenta[b]pyrrole and 80 mg of squaric acid were mixed in 5 mL of ethanol, and the mixture was stirred at 80° C. for 2 hours. After that, the mixture was cooled to room temperature, and the product was filtered out. The product that had been filtered out was washed with ethanol, and was dried under reduced pressure at 70° C. to provide 197 mg of a squaraine compound. Further, the compound was purified by silica gel chromatography to provide 120 mg of a squaraine compound.

(Optical Laminate)

The wavelength conversion layer (1) and the absorption layer (1) were laminated to provide an optical laminate (1) having the laminated structure“wavelength conversion layer/absorption layer”. The optical laminate (1) was subjected to the above-mentioned evaluations. The results are shown in Table 1.

Comparative Example 1

An optical laminate (2) including the wavelength conversion layer (1) and an absorption layer (1) (absorption maximum wavelength: 595 nm) was obtained in the same manner as in Example 1 except that 0.3 part by weight of a porphyrin-based coloring matter (manufactured by Yamamoto Chemicals, Inc., product name: “PD-320”) was used instead of 0.3 part by weight of the squaraine compound represented by the general formula (I-20). The optical laminate (2) was subjected to the above-mentioned evaluations. The results are shown in Table 1.

Comparative Example 2

An optical laminate (3) was obtained in the same manner as in Example 1 except that the coloring matter (squaraine compound) was not incorporated into the pressure-sensitive adhesive for forming the absorption layer (i.e., a pressure-sensitive adhesive layer was formed instead of the absorption layer). The optical laminate (3) was subjected to the above-mentioned evaluations. The results are shown in Table 1.

TABLE 1 Coloring matter a b* Δab Example 1 Squaraine compound −0.96 5.9 6 Comparative Porphyrin compound −7.7 −2.7 8.2 Example 1 Comparative — −3.8 33 33 Example 2

INDUSTRIAL APPLICABILITY

The optical laminate of the present invention may be suitably utilized in an image display apparatus.

REFERENCE SIGNS LIST

10 wavelength conversion layer

  • 20 absorption layer
  • 100 optical laminate
  • 200 liquid crystal panel
  • 300 backlight
  • 1000 liquid crystal display apparatus

Claims

1. A optical laminate, comprising: in the formula (I),

a wavelength conversion layer; and
an absorption layer arranged on one side of the wavelength conversion layer,
wherein the absorption layer has an absorption peak in a wavelength band in a range of from 580 nm to 610 nm, and
wherein the absorption layer contains a compound X represented by the following general formula (I) or general formula (II):
R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),
R1 and R2 form a saturated cyclic skeleton including 5 or 6 carbon atoms, and R3, R4, R5, R6, R7, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),
R2 and R3 form a saturated cyclic skeleton including 5 to 7 carbon atoms, and R1, R4, R5, R6, R7, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),
R5 and R6 form a saturated cyclic skeleton including 5 or 6 carbon atoms, and R1, R2, R3, R4, R7, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),
R6 and R7 form a saturated cyclic skeleton including 5 to 7 carbon atoms, and R1, R2, R3, R4, R5, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b),
R1 and R2 form a saturated cyclic skeleton including 5 or 6 carbon atoms, R5 and R6 form a saturated cyclic skeleton including 5 or 6 carbon atoms, and R3, R4, R7, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b), or
R2 and R3 form a saturated cyclic skeleton including 5 to 7 carbon atoms, R6 and R7 form a saturated cyclic skeleton including 5 to 7 carbon atoms, and R1, R4, R5, and R8 each independently represent a hydrogen atom, a halogen atom, which is preferably Cl, a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms, a substituent represented by the formula (a), or a substituent represented by the formula (b); and
in the formula (II), R4 and R8 each independently represent a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 or more and 20 or less carbon atoms.

2. The optical laminate according to claim 1, wherein the optical laminate is free of a polarizing plate on a side of the absorption layer opposite to the wavelength conversion layer.

3. The optical laminate according to claim 1, wherein the wavelength conversion layer contains quantum dots or a phosphor as a wavelength conversion material.

4. The optical laminate according to claim 1, wherein the wavelength conversion layer is a color filter.

5. An image display apparatus, comprising the optical laminate of claim 1.

6. The image display apparatus according to claim 5, wherein the image display apparatus comprises a liquid crystal panel including the optical laminate of claim 1, and a backlight.

7. The image display apparatus according to claim 6, wherein the liquid crystal panel includes the absorption layer, the wavelength conversion layer, a viewer-side polarizing plate, a liquid crystal cell, and a backlight-side polarizing plate in the stated order from a viewer side.

Patent History
Publication number: 20200292877
Type: Application
Filed: Nov 29, 2018
Publication Date: Sep 17, 2020
Applicant: NITTO DENKO CORPORATION (Ibaraki-shi, Osaka)
Inventors: Kozo Nakamura (Ibaraki-shi), Peng Wang (San Diego, CA), Michael Welch (San Diego, CA), Shijun Zheng (San Diego, CA)
Application Number: 16/767,825
Classifications
International Classification: G02F 1/1335 (20060101); H01L 33/50 (20060101); C07D 403/08 (20060101);