JP2023028515A - Wavelength conversion member, manufacturing method therefor, backlight unit, image display device, light scattering member, and light scattering layer-forming composition - Google Patents

Abstract

To provide a wavelength conversion member capable of suppressing appearance of LED unevenness and reduction in brightness while minimizing an increase in thickness.SOLUTION: A wavelength conversion member provided herein comprises a wavelength conversion layer containing a phosphor, and a light scattering layer configured to contain filler particles and a resin and disposed on at least one side of the wavelength conversion layer. A proportion of the filler particles with respect to the entire light scattering layer is in a range of 7-50 mass%.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present disclosure relates to a wavelength conversion member and its manufacturing method, a backlight unit, an image display device, a light scattering member, and a composition for forming a light scattering layer.

Laminates in which coating materials such as resin sheets are arranged on both sides of an intermediate layer are used in many technical fields. For example, as a means for improving the color reproducibility of the display of an image display device such as a liquid crystal display device, a wavelength conversion member comprising a layer containing a quantum dot phosphor and coating materials provided on both sides thereof is known ( For example, see Patent Document 1).

A wavelength conversion member containing a quantum dot phosphor is arranged, for example, in a backlight unit of an image display device. When using a wavelength conversion member containing a quantum dot phosphor that emits red light and a quantum dot phosphor that emits green light, when the wavelength conversion member is irradiated with blue light as excitation light, the quantum dot phosphor emits light White light can be obtained from the converted red light and green light and the blue light transmitted through the wavelength conversion member.

In recent years, there is an increasing demand for higher brightness in backlight units used in mobile electronic devices, next-generation 4K or higher image display devices, and the like. Applying a direct type backlight is effective for increasing the brightness of liquid crystal displays. LED (Light Emitting Diode) backlights for liquid crystal displays include an edge light type and a direct type, and the direct type has higher brightness.
Conventionally, since the LEDs and their supporting substrates were large, it was difficult to apply a direct type backlight to a thin structure such as a mobile electronic device. However, in recent years, the miniaturization of LEDs (mini-LEDs) has progressed, and the possibility of adopting direct type backlights even in mobile electronic devices is increasing. The direct type Mini-LED backlight is capable of local brightness control (local dimming) while maintaining high brightness, and has the advantage of saving power. Also, since the screen with local brightness control has a high contrast, it is also excellent in terms of image quality.

Japanese Patent No. 6202023

The Mini-LED backlight has strong directivity, and the LED unevenness that makes it possible to see the light source through the liquid crystal film is a problem. In addition, the distance between the wavelength conversion member and the light source is narrowed due to the thinning of the liquid crystal display itself, which tends to make the LED unevenness worse. In order to eliminate the LED unevenness, it is necessary to increase the number of light diffusion plates incorporated in the liquid crystal display module, or to increase the thickness of the base material, the light scattering layer, and the like. However, if the LED unevenness is eliminated by the above method, the luminance is reduced and the thickness of the liquid crystal display is increased. Therefore, there is a demand for a new method of eliminating LED unevenness without increasing the thickness of the liquid crystal display.
The present disclosure has been made in view of the above-described conventional circumstances, and one aspect of the present disclosure is a wavelength conversion member that can suppress the occurrence of LED unevenness and the decrease in luminance while suppressing an increase in thickness, and a method for manufacturing the same. Another object of the present invention is to provide a backlight unit and an image display device using this wavelength conversion member. Another object of the present disclosure is to provide a light scattering member and a composition for forming a light scattering layer used for manufacturing a wavelength conversion member capable of suppressing the occurrence of LED unevenness and a decrease in luminance. .

Specific means for achieving the above object are as follows.
<1> A wavelength conversion layer containing a phosphor, and a light scattering layer containing filler particles and a resin disposed on at least one side of the wavelength conversion layer,
The wavelength conversion member, wherein the filler particles account for 7% by mass to 50% by mass of the entire light scattering layer.
<2> The wavelength conversion member according to <1>, wherein the surface of the light scattering layer has projections caused by the filler particles.
<3> The wavelength conversion member according to <2>, wherein the average height of the protrusions is 7 μm or less.
<4> The wavelength conversion member according to any one of <1> to <3>, wherein the filler particles have a refractive index of 1.70 or less.
<5> The wavelength conversion member according to any one of <1> to <4>, wherein the filler particles are particles of at least one selected from the group consisting of acrylic resins and silicone resins.
<6> The wavelength conversion member according to any one of <1> to <5>, wherein the phosphor contains a quantum dot phosphor.
<7> The quantum dot phosphor is a first quantum dot phosphor that converts light of 430 nm to 480 nm into light of 520 nm to 560 nm, and a second quantum that converts light of 430 nm to 480 nm into light of 600 nm to 680 nm. The wavelength conversion member according to <6>, which contains at least one dot phosphor.
<8><1> to <7, wherein the wavelength conversion layer contains light scattering particles, and the content of the light scattering particles is 0.5% by mass to 20% by mass with respect to the entire wavelength conversion layer The wavelength conversion member according to any one of >.
<9> The wavelength conversion member according to <8>, wherein the light scattering particles are at least one particle selected from the group consisting of acrylic resin, silicone resin, zirconia, alumina, titanium oxide and silica.
<10> The wavelength conversion member according to any one of <1> to <9>, which has a covering material covering at least part of the wavelength conversion layer.
<11> The wavelength conversion member according to <10>, wherein the covering material has an average thickness of 10 μm to 150 μm.
<12> The wavelength conversion member according to <10> or <11>, wherein the coating material has a barrier property against at least one of oxygen and water.
<13> The wavelength conversion member according to any one of <10> to <12>, wherein the light scattering layer is disposed on a surface of the coating material opposite to the surface facing the wavelength conversion layer.
<14> The wavelength conversion member according to any one of <1> to <13>, further comprising a wavelength selective transmission layer.
<15> The wavelength conversion member according to any one of <1> to <14>, wherein the wavelength conversion layer has an average thickness of 40 μm to 120 μm.
<16> A backlight unit comprising the wavelength conversion member according to any one of <1> to <15> and a light source.
<17> An image display device comprising the backlight unit according to <16>.
<18> having a base material and a light scattering layer containing filler particles and a resin disposed on one side of the base material,
The light-scattering member, wherein the filler particles account for 7% by mass to 50% by mass of the entire light-scattering layer.
<19> Containing filler particles, a resin, and a solvent,
A composition for forming a light-scattering layer, wherein the filler particles account for 7% by mass to 50% by mass of the total solid content.
<20> A wavelength including arranging the light scattering member according to <18> on at least one surface side of a wavelength conversion layer containing a phosphor such that the substrate side surface faces the wavelength conversion layer A method for manufacturing a conversion member.
<21> applying the composition for forming a light scattering layer according to <19> to at least one side of the wavelength conversion layer containing a phosphor to form a coating film;
A method for producing a wavelength conversion member, including drying the coating film.

According to one aspect of the present disclosure, a wavelength conversion member that can suppress the occurrence of LED unevenness and a decrease in luminance while suppressing an increase in thickness, a method for manufacturing the same, and a backlight unit and an image using the wavelength conversion member A display device can be provided. Further, according to another aspect of the present disclosure, it is possible to provide a light scattering member and a composition for forming a light scattering layer, which are used for manufacturing a wavelength conversion member capable of suppressing the occurrence of LED unevenness and a decrease in brightness.

It is a schematic cross section which shows an example of schematic structure of a wavelength conversion member. It is a figure which shows an example of schematic structure of a backlight unit. It is a figure which shows an example of schematic structure of a liquid crystal display device.

Hereinafter, embodiments for implementing the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps and the like) are not essential unless otherwise specified. The same applies to numerical values and their ranges, which do not limit the present disclosure.

In the present disclosure, the numerical range indicated using "-" includes the numerical values before and after "-" as the minimum and maximum values, respectively.
In the numerical ranges described step by step in the present disclosure, the upper limit or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described step by step. . Moreover, in the numerical ranges described in the present disclosure, the upper or lower limits of the numerical ranges may be replaced with the values shown in the examples.
In the present disclosure, each component may contain multiple types of applicable substances. When there are multiple types of substances corresponding to each component in the composition, the content rate or content of each component is the total content rate or content of the multiple types of substances present in the composition unless otherwise specified. means quantity.
In the present disclosure, the particles corresponding to each component may include multiple types of particles. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means a value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.
In the present disclosure, the term “layer” or “film” refers to the case where the layer or film is formed in the entire region when observing the region where the layer or film is present, and only a part of the region. It also includes the case where it is formed.
In the present disclosure, the term "laminate" indicates stacking layers, and two or more layers may be bonded, or two or more layers may be detachable.
In the present disclosure, "(meth) acryloyl group" means at least one of acryloyl group and methacryloyl group, "(meth) acrylic" means at least one of acrylic and methacrylic, "(meth) acrylate" means acrylate and methacrylate, and "(meth)allyl" means at least one of allyl and methallyl.
In the present disclosure, the average thickness of a layer or film is a value obtained by measuring the thickness of the target layer or film at five points and giving the arithmetic mean value.
The thickness of a layer or film can be measured using a micrometer or the like. In this disclosure, when the thickness of a layer or film can be measured directly, it is measured using a micrometer. On the other hand, when measuring the thickness of one layer or the total thickness of a plurality of layers, the thickness may be measured by observing the cross section of the object to be measured using an electron microscope.

<Wavelength conversion member>
The wavelength conversion member of the present disclosure has a wavelength conversion layer containing a phosphor, and a light scattering layer containing filler particles and a resin disposed on at least one side of the wavelength conversion layer, and the entire light scattering layer The ratio of the filler particles to the total amount is set to 7% by mass to 50% by mass.
The present inventors have found that by setting the ratio of filler particles in the entire light scattering layer to 7% by mass to 50% by mass, the wavelength conversion that can suppress the occurrence of LED unevenness and the decrease in luminance while suppressing the increase in thickness. The inventors have found that the member can be obtained, and completed the present invention.

From the viewpoint of ensuring sufficient brightness, the wavelength conversion member preferably has a total light transmittance of 65% or more, more preferably 70% or more, and even more preferably 75% or more. The total light transmittance of the wavelength conversion member may be 100% or less. The total light transmittance of the wavelength conversion member is obtained by a method conforming to JIS K 7136:2000.
From the viewpoint of suppressing brightness unevenness of an image, the haze of the wavelength conversion member is preferably 90% or more, more preferably 93% or more, and even more preferably 95% or more. The haze of the wavelength conversion member may be 100% or less. The haze of the wavelength conversion member is obtained by a method conforming to JIS K 7136:2000.

Hereinafter, other components such as the wavelength conversion layer, the light scattering layer, the coating material included as necessary, and the wavelength selective transmission layer, which are included in the wavelength conversion member of the present disclosure, and the components included in these components etc. will be explained.

-Wavelength conversion layer-
The wavelength conversion layer contains a phosphor and functions to convert light incident from the light source into light of another wavelength.
From the viewpoint of obtaining a sufficient wavelength conversion effect, the average thickness of the wavelength conversion layer may be 40 μm or more, 45 μm or more, or 50 μm or more. From the viewpoint of corresponding to thinning of the image display device, the average thickness of the wavelength conversion layer may be 120 μm or less, 100 μm or less, or 90 μm or less.
In one aspect, the average thickness of the wavelength conversion layer is preferably 40 μm to 120 μm, more preferably 45 μm to 100 μm, even more preferably 50 μm to 90 μm.

(Phosphor)
The type of phosphor contained in the wavelength conversion layer is not particularly limited, and can be selected according to the application. Examples of phosphors include organic phosphors and inorganic phosphors.

Organic phosphors include naphthalimide compounds, perylene compounds, and the like.
Examples of inorganic phosphors include Y ₃ O ₃ :Eu, YVO ₄ :Eu, Y ₂ O ₂ :Eu, 3.5MgO·0.5MgF ₂ , GeO ₂ :Mn, and (Y·Cd)BO ₂ :Eu. Red-emitting inorganic phosphor, ZnS: Cu-Al, (Zn-Cd) S: Cu-Al, ZnS: Cu-Au-Al, _Zn2SiO4 : _Mn , ZnSiO4: _Mn , ZnS: Ag-Cu, ( Zn-Cd) S: Cu, ZnS: Cu, _CdOS : Tb, LaOS: Tb, YSiO4: Ce-Tb, _ZnGeO4 : Mn, GeMgAlO: Tb, SrGaS: Eu2 ⁺ , ZnS: Cu-Co, MgO-nB _2O3 :Ge.Tb, _LaOBr :Tb.Tm, _La2O2S :Tb and other green-emitting inorganic phosphors, ZnS:Ag, _GaWO4 , _Y2SiO6 : _Ce , _ZnS :Ag.Ga.Cl , Ca ₂ B ₄ OCl:Eu ²⁺ , BaMgAl ₄ O ₃ :Eu ²⁺ , blue-emitting inorganic phosphors, quantum dot phosphors, and the like.

From the viewpoint of color reproducibility, the wavelength conversion layer preferably contains a quantum dot phosphor. Quantum dot phosphors are not particularly limited, and include particles containing at least one selected from the group consisting of II-VI compounds, III-V compounds, IV-VI compounds, and IV compounds.

Specific examples of II-VI compounds include CdSe, CdTe, CdS, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS , CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe.
Specific examples of III-V compounds include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaGaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb , AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, and the like.
Specific examples of IV-VI compounds include SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, etc. .
Specific examples of Group IV compounds include Si, Ge, SiC, SiGe and the like.

From the viewpoint of luminous efficiency, the quantum dot phosphor preferably contains at least one of Cd and In. From the viewpoint of compliance with environmental regulations, the quantum dot phosphor preferably does not contain Cd. Therefore, from the viewpoint of luminous efficiency and compliance with environmental regulations, the quantum dot phosphor preferably contains In.
From the viewpoint of reducing the amount of Cd in the entire quantum dot phosphor, a quantum dot phosphor containing no Cd and a quantum dot phosphor containing Cd may be used together.

The quantum dot phosphor may have a core-shell structure. By making the bandgap of the compound forming the shell wider than that of the compound forming the core, it is possible to further improve the quantum efficiency of the quantum dot phosphor. Combinations of core and shell (core/shell) include CdSe/ZnS, InP/ZnS, PbSe/PbS, CdSe/CdS, CdTe/CdS, CdTe/ZnS, and the like.

The quantum dot phosphor may have a so-called core-multi-shell structure in which the shell has a multi-layer structure. To further improve the quantum efficiency of a quantum dot phosphor by stacking one or more layers of a shell with a narrow bandgap on a core with a wide bandgap, and further stacking a shell with a wide bandgap on top of this shell. becomes possible.

When the wavelength conversion layer contains quantum dot phosphors, two or more kinds of quantum dot phosphors having different components, average particle sizes, layer structures, etc. may be combined. By combining two or more kinds of quantum dot phosphors, the central emission wavelength of the wavelength conversion layer as a whole can be adjusted to a desired value.

The phosphor may include a phosphor G having an emission central wavelength in the green wavelength range of 520 nm to 560 nm and a phosphor R having an emission central wavelength in the red wavelength range of 600 nm to 680 nm.
When the phosphor contains a quantum dot phosphor, the quantum dot phosphor is a first quantum dot phosphor that converts light of 430 nm to 480 nm into light of 520 nm to 560 nm and light of 430 nm to 480 nm to light of 600 nm to 680 nm. Preferably, at least one of the second quantum dot phosphors that convert to

When the wavelength conversion layer containing phosphor G and phosphor R is irradiated with excitation light in a blue wavelength range of 430 nm to 480 nm, green light and red light are emitted from phosphor G and phosphor R, respectively. As a result, white light can be obtained from the green light and red light emitted from the phosphor G and the phosphor R and the blue light transmitted through the wavelength conversion layer.

The content of the phosphor in the wavelength conversion layer may be, for example, 0.01% by mass or more, 0.05% by mass or more, or 0.1% by mass or more with respect to the entire wavelength conversion layer. can be Moreover, it may be 1.0% by mass or less, 0.8% by mass or less, or 0.7% by mass or less. When the content of the phosphor is 0.01% by mass or more, a sufficient wavelength conversion function tends to be obtained, and when the content of the phosphor is 1.0% by mass or less, aggregation of the phosphor is suppressed. tend to be
From the viewpoint of ensuring a sufficient wavelength conversion function and suppressing aggregation of the phosphor, the content of the phosphor in the wavelength conversion layer is 0.01% by mass to 1.0% by mass with respect to the entire wavelength conversion layer. It is preferably 0.05% by mass to 0.8% by mass, and even more preferably 0.1% by mass to 0.7% by mass.

(light scattering particles)
The wavelength conversion layer may contain light scattering particles. The light scattering particles act to scatter light incident on the wavelength conversion layer within the wavelength conversion layer to increase the wavelength conversion efficiency of the incident light by the phosphor.

Light scattering particles include particles of acrylic resin, silicone resin, zirconia, alumina, titanium oxide, silica, zinc oxide, barium sulfate, calcium carbonate, and the like. Among these, particles of at least one selected from the group consisting of acrylic resins, silicone resins, zirconia, alumina, titanium oxide and silica are preferred, and titanium oxide particles are more preferred.

From the viewpoint of obtaining a sufficient light scattering effect, the content of the light scattering particles may be 0.1% by mass or more, or 0.2% by mass or more, relative to the entire wavelength conversion layer. , 0.3% by mass or more. From the viewpoint of ensuring sufficient brightness, the content of the light scattering particles may be 3% by mass or less, 2% by mass or less, or 1% by mass or less.
From the viewpoint of obtaining a light scattering effect and ensuring sufficient brightness, the content of the light scattering particles is preferably 0.1% by mass to 3% by mass with respect to the entire wavelength conversion layer, and 0.2% by mass. It is more preferably 0.3% to 1% by mass, more preferably 0.3% to 1% by mass.

From the viewpoint of ease of forming the wavelength conversion layer, the average particle size of the light scattering particles may be 2.0 μm or less, 1.5 μm or less, or 1.0 μm or less. .
From the viewpoint of suppressing variations in the thickness of the wavelength conversion layer, the average particle size of the light scattering particles may be 0.1 μm or more, 0.2 μm or more, or 0.3 μm or more.
From the viewpoints of easy formation of the wavelength conversion layer and suppression of variations in thickness, the average particle size of the light scattering particles is preferably 0.1 μm to 2.0 μm, more preferably 0.2 μm to 1.5 μm, and more preferably 0.3 μm to 0.3 μm. 1.0 μm is more preferred.

The light scattering particles may be surface-treated with a coupling agent from the viewpoint of suppressing variations in the thickness of the wavelength conversion layer. Examples of coupling agents include silane compounds having primary, secondary or tertiary amino groups, epoxysilanes, mercaptosilanes, alkylsilanes, ureidosilanes, various silane compounds such as vinylsilanes, titanium compounds, aluminum chelate compounds, aluminum and zirconium. containing compounds and the like.

Specifically, the average particle size of the light scattering particles can be measured as follows.
A dispersion liquid is obtained by dispersing light scattering particles in purified water containing a surfactant. Using this dispersion, in the volume-based particle size distribution measured by a laser diffraction particle size distribution analyzer (for example, Shimadzu Corporation, SALD-3000J), the value when the integration from the small diameter side is 50% ( The median diameter (D50)) is taken as the average particle diameter of the light scattering particles.
The average particle diameter of the light scattering particles contained in the wavelength conversion layer is obtained by calculating the equivalent circle diameter (the geometric mean of the major and minor diameters) of 50 particles by observing the particles using a scanning electron microscope. , may be obtained as its arithmetic mean.

-Resin composition for wavelength conversion-
The wavelength conversion layer may be in the form of a cured product containing phosphors and optionally light scattering particles. Such a cured product is obtained, for example, by curing a composition (wavelength conversion resin composition) containing at least a phosphor and optionally light scattering particles, a polymerizable compound, and a photopolymerization initiator. It may be obtained.

(Polymerizable compound)
The polymerizable compound contained in the wavelength conversion resin composition is not particularly limited, and examples thereof include thiol compounds, (meth)allyl compounds, and (meth)acrylic compounds.

When a coating material is provided on the surface of the wavelength conversion layer, from the viewpoint of adhesion between the wavelength conversion layer and the coating material, the polymerizable compounds include a thiol compound, a (meth)allyl compound, and a (meth)acrylic compound. and at least one selected from the group consisting of.

A wavelength conversion layer obtained by curing a wavelength conversion resin composition containing a thiol compound as a polymerizable compound and at least one selected from the group consisting of (meth)allyl compounds and (meth)acrylic compounds, A sulfide structure formed by an enethiol reaction between a thiol group and a carbon-carbon double bond of a (meth)allyl group or a (meth)acryloyl group (RSR', R and R' are organic groups ). This tends to improve the adhesion between the wavelength conversion layer and the covering material. Also, the optical properties of the wavelength conversion layer tend to be further improved.

(1) thiol compound thiol compound may be a monofunctional thiol compound having one thiol group in one molecule, even a polyfunctional thiol compound having two or more thiol groups in one molecule good. The number of thiol compounds contained in the wavelength conversion resin composition may be one or two or more.

The thiol compound may or may not have a polymerizable group (eg, (meth)acryloyl group, (meth)allyl group) other than the thiol group in the molecule.
In the present disclosure, a compound containing a thiol group and a polymerizable group other than the thiol group in the molecule is classified as a "thiol compound."

Specific examples of monofunctional thiol compounds include hexanethiol, 1-heptanethiol, 1-octanethiol, 1-nonanethiol, 1-decanethiol, 3-mercaptopropionic acid, methyl mercaptopropionate, methoxybutyl mercaptopropionate, octyl mercaptopropionate, tridecyl mercaptopropionate, 2-ethylhexyl-3-mercaptopropionate, n-octyl-3-mercaptopropionate and the like.

Specific examples of polyfunctional thiol compounds include ethylene glycol bis (3-mercaptopropionate), diethylene glycol bis (3-mercaptopropionate), tetraethylene glycol bis (3-mercaptopropionate), 1, 2- Propylene glycol bis(3-mercaptopropionate), diethylene glycol bis(3-mercaptobutyrate), 1,4-butanediol bis(3-mercaptopropionate), 1,4-butanediol bis(3-mercaptobutyrate) rate), 1,8-octanediol bis(3-mercaptopropionate), 1,8-octanediol bis(3-mercaptobutyrate), hexanediol bisthioglycolate, trimethylolpropane tris(3-mercaptopropionate) pionate), trimethylolpropane tris (3-mercaptobutyrate), trimethylolpropane tris (3-mercaptoisobutyrate), trimethylolpropane tris (2-mercaptoisobutyrate), trimethylolpropane tristhioglycolate, Tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, trimethylolethane tris(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate) ), pentaerythritol tetrakis (3-mercaptoisobutyrate), pentaerythritol tetrakis (2-mercaptoisobutyrate), dipentaerythritol hexakis (3-mercaptopropionate), dipentaerythritol hexakis (2-mercaptopropionate) pionate), dipentaerythritol hexakis (3-mercaptobutyrate), dipentaerythritol hexakis (3-mercaptoisobutyrate), dipentaerythritol hexakis (2-mercaptoisobutyrate), pentaerythritol tetrakis thioglyco rate, dipentaerythritol hexakisthioglycolate, and the like.

From the viewpoint of further improving the adhesion between the wavelength conversion layer and the coating material, heat resistance, and resistance to moist heat, the thiol compound preferably contains a polyfunctional thiol compound. The ratio of the polyfunctional thiol compound to the total amount of the thiol compound is, for example, preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more. The ratio of the polyfunctional thiol compound to the total amount of the thiol compound may be 100% by mass or less.

The thiol compound may be in the form of a thioether oligomer reacted with a (meth)acrylic compound. A thioether oligomer can be obtained by subjecting a thiol compound and a (meth)acrylic compound to addition polymerization in the presence of a polymerization initiator.

Among thioether oligomers, a thioether oligomer obtained by reacting a polyfunctional thiol compound and a polyfunctional (meth)acrylic compound is preferred from the viewpoint of further improving the optical properties, heat resistance, and resistance to moist heat of the cured product, and pentaerythritol. A thioether oligomer obtained by addition polymerization of tetrakis(3-mercaptopropionate) and tris(2-acryloyloxyethyl)isocyanurate is more preferred.

The weight average molecular weight of the thioether oligomer is, for example, preferably 3,000 to 10,000, more preferably 3,000 to 8,000, even more preferably 4,000 to 6,000.
The weight-average molecular weight of the thioether oligomer is obtained by converting the molecular weight distribution measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve.

Further, the thiol equivalent of the thioether oligomer is, for example, preferably 200 g/eq to 400 g/eq, more preferably 250 g/eq to 350 g/eq, and further preferably 250 g/eq to 270 g/eq. preferable.

In addition, the thiol equivalent of the thioether oligomer can be measured by the following iodine titration method.
0.2 g of a measurement sample is accurately weighed, and 20 mL of chloroform is added thereto to obtain a sample solution. Using 0.275 g of soluble starch dissolved in 30 g of pure water as a starch indicator, 20 mL of pure water, 10 mL of isopropyl alcohol, and 1 mL of starch indicator are added and stirred with a stirrer. An iodine solution was added dropwise, and the point at which the chloroform layer turned green was taken as the end point. At this time, the value given by the following formula is taken as the thiol equivalent of the measurement sample.
Thiol equivalent (g/eq) = mass of measurement sample (g) x 10000/titration volume of iodine solution (mL) x factor of iodine solution

When the wavelength conversion resin composition contains a thiol compound, the content of the thiol compound in the wavelength conversion resin composition is, for example, 5% by mass to 80% by mass with respect to the total amount of the wavelength conversion resin composition. Preferably, it is more preferably 15% by mass to 70% by mass, and more preferably 20% by mass to 60% by mass When the content of the thiol compound is 5% by mass or more, the cured product Adhesion to the coating material tends to be further improved, and when the content of the thiol compound is 80% by mass or less, the heat resistance and moist heat resistance of the cured product tend to be further improved.

(2) (meth)allyl compound The (meth)allyl compound may be a monofunctional (meth)allyl compound having one (meth)allyl group in one molecule, or two or more in one molecule. It may be a polyfunctional (meth)allyl compound having a (meth)allyl group. The (meth)allyl compound contained in the wavelength conversion resin composition may be of one type or two or more types.

The (meth)allyl compound may or may not have a polymerizable group (for example, a (meth)acryloyl group) other than the (meth)allyl group in the molecule.
In the present disclosure, compounds having polymerizable groups other than (meth)allyl groups in the molecule (excluding thiol compounds) shall be classified as "(meth)allyl compounds".

Specific examples of monofunctional (meth)allyl compounds include (meth)allyl acetate, (meth)allyl n-propionate, (meth)allyl benzoate, (meth)allylphenyl acetate, (meth)allylphenoxyacetate, (meth) Allyl methyl ether, (meth)allyl glycidyl ether and the like can be mentioned.

Specific examples of polyfunctional (meth)allyl compounds include di(meth)allyl benzenedicarboxylate, di(meth)allyl cyclohexanedicarboxylate, di(meth)allyl maleate, di(meth)allyl adipate, di(meth) allyl phthalate, di(meth)allyl isophthalate, di(meth)allyl terephthalate, glycerin di(meth)allyl ether, trimethylolpropane di(meth)allyl ether, pentaerythritol di(meth)allyl ether, 1,3-di (meth)allyl-5-glycidyl isocyanurate, tri(meth)allyl cyanurate, tri(meth)allyl isocyanurate, tri(meth)allyl trimellitate, tetra(meth)allyl pyromellitate, 1, 3, 4 , 6-tetra(meth)allylglycoluril, 1,3,4,6-tetra(meth)allyl-3a-methylglycoluril, 1,3,4,6-tetra(meth)allyl-3a,6a-dimethyl glycoluril and the like.

As the (meth)allyl compound, compounds having an isocyanurate skeleton such as tri(meth)allyl isocyanurate, tri(meth)allyl cyanurate, benzenedicarboxylic acid di(meth) ) allyl and di(meth)allyl cyclohexanedicarboxylate, more preferably a compound having an isocyanurate skeleton, and still more preferably tri(meth)allyl isocyanurate.

(3) (meth)acrylic compound The (meth)acrylic compound may be a monofunctional (meth)acrylic compound having one (meth)acryloyl group per molecule, or two or more per molecule. It may be a polyfunctional (meth)acrylic compound having a (meth)acryloyl group. One or two or more (meth)acrylic compounds may be contained in the wavelength conversion resin composition.

Specific examples of monofunctional (meth)acrylic compounds include (meth)acrylic acid; methyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, ) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, alkyl (meth) acrylate having 1 to 18 carbon atoms in the alkyl group such as stearyl (meth) acrylate; benzyl (meth) acrylate, phenoxyethyl ( (meth)acrylate compounds having an aromatic ring such as meth)acrylate; alkoxyalkyl (meth)acrylates such as butoxyethyl (meth)acrylate; aminoalkyl (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate; Diethylene glycol monoethyl ether (meth) acrylate, triethylene glycol monobutyl ether (meth) acrylate, tetraethylene glycol monomethyl ether (meth) acrylate, hexaethylene glycol monomethyl ether (meth) acrylate, octaethylene glycol monomethyl ether (meth) acrylate, nona Polyalkylene glycol monoalkyl ethers (meth) such as ethylene glycol monomethyl ether (meth) acrylate, dipropylene glycol monomethyl ether (meth) acrylate, heptapropylene glycol monomethyl ether (meth) acrylate, tetraethylene glycol monoethyl ether (meth) acrylate, etc. Acrylates; polyalkylene glycol monoaryl ether (meth)acrylates such as hexaethylene glycol monophenyl ether (meth)acrylate; cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, methylene oxide-added cyclo (Meth)acrylate compounds having an alicyclic structure such as decatriene (meth)acrylate; (meth)acrylate compounds having a heterocyclic ring such as (meth)acryloylmorpholine and tetrahydrofurfuryl (meth)acrylate; heptadecafluorodecyl (meth) ) Fluorinated alkyl (meth)acrylates such as acrylate; 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, triethylene (Meth)acrylate compounds having a hydroxyl group such as glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, hexaethylene glycol mono(meth)acrylate, octapropylene glycol mono(meth)acrylate; glycidyl (meth)acrylate, etc. (Meth) acrylate compounds having a glycidyl group; 2-(2-(meth) acryloyloxyethyloxy) ethyl isocyanate, 2-(meth) acryloyloxyethyl isocyanate, etc. (meth) acrylate compounds having an isocyanate group; tetraethylene Polyalkylene glycol mono(meth)acrylates such as glycol mono(meth)acrylate, hexaethylene glycol mono(meth)acrylate, octapropylene glycol mono(meth)acrylate; (meth)acrylamide, N,N-dimethyl(meth)acrylamide, (meth)acrylamide compounds such as N-isopropyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, 2-hydroxyethyl (meth)acrylamide; .

Specific examples of polyfunctional (meth)acrylic compounds include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and the like. Alkylene glycol di (meth) acrylate; polyalkylene glycol di (meth) acrylate such as polyethylene glycol di (meth) acrylate and polypropylene glycol di (meth) acrylate; trimethylol propane tri (meth) acrylate, ethylene oxide added trimethylol propane tri ( meth)acrylates, tri(meth)acrylate compounds such as tris(2-acryloyloxyethyl)isocyanurate; ethylene oxide-added pentaerythritol tetra(meth)acrylate, trimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, etc. Tetra (meth) acrylate compounds of; meth) acrylate, hydrogenated bisphenol A (poly) propoxy di (meth) acrylate, hydrogenated bisphenol F (poly) ethoxy di (meth) acrylate, hydrogenated bisphenol F (poly) propoxy di (meth) acrylate, hydrogenated bisphenol S (poly) Examples include (meth)acrylate compounds having an alicyclic structure such as ethoxydi(meth)acrylate and hydrogenated bisphenol S (poly)propoxydi(meth)acrylate.

The (meth)acrylic compound is preferably a (meth)acrylate compound having an alicyclic structure or an aromatic ring structure from the viewpoint of further improving the heat resistance and moist heat resistance of the cured product. The alicyclic structure or aromatic ring structure includes an isobornyl skeleton, a tricyclodecane skeleton, a bisphenol skeleton, and the like.

The (meth)acrylic compound may have an alkyleneoxy group, or may be a bifunctional (meth)acrylic compound having an alkyleneoxy group.

As the alkyleneoxy group, for example, an alkyleneoxy group having 2 to 4 carbon atoms is preferable, an alkyleneoxy group having 2 or 3 carbon atoms is more preferable, and an alkyleneoxy group having 2 carbon atoms is even more preferable.
The (meth)acrylic compound may have one or more alkyleneoxy groups.

The alkyleneoxy group-containing compound may be a polyalkyleneoxy group-containing compound having a polyalkyleneoxy group containing a plurality of alkyleneoxy groups.

(Meth) when the acrylic compound has an alkyleneoxy group, the number of alkyleneoxy groups in one molecule is preferably 2 to 30, more preferably 2 to 20, 3 to It is more preferably 10, and particularly preferably 3 to 5.

When the (meth)acrylic compound has an alkyleneoxy group, it preferably has a bisphenol structure. Thereby, it tends to be more excellent in heat resistance. The bisphenol structure includes, for example, a bisphenol A structure and a bisphenol F structure, with the bisphenol A structure being preferred.

Specific examples of (meth)acrylic compounds containing an alkyleneoxy group include alkoxyalkyl (meth)acrylates such as butoxyethyl (meth)acrylate; diethylene glycol monoethyl ether (meth)acrylate, triethylene glycol monobutyl ether (meth)acrylate , tetraethylene glycol monomethyl ether (meth) acrylate, hexaethylene glycol monomethyl ether (meth) acrylate, octaethylene glycol monomethyl ether (meth) acrylate, nonaethylene glycol monomethyl ether (meth) acrylate, dipropylene glycol monomethyl ether (meth) acrylate , polyalkylene glycol monoalkyl ether (meth)acrylates such as heptapropylene glycol monomethyl ether (meth)acrylate and tetraethylene glycol monoethyl ether (meth)acrylate; polyalkylene glycol monoalkyl ether (meth)acrylates such as hexaethylene glycol monophenyl ether (meth)acrylate; Aryl ether (meth) acrylate; (meth) acrylate compounds having a heterocyclic ring such as tetrahydrofurfuryl (meth) acrylate; triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate, hexaethylene glycol mono (meth) ) Acrylate, octapropylene glycol mono (meth) acrylate having a hydroxyl group (meth) acrylate compounds; glycidyl (meth) acrylate having a glycidyl group (meth) acrylate compounds; polyethylene glycol di (meth) acrylate, polypropylene glycol di Polyalkylene glycol di(meth)acrylates such as (meth)acrylates; tri(meth)acrylate compounds such as ethylene oxide-added trimethylolpropane tri(meth)acrylate; tetra(meth)acrylates such as ethylene oxide-added pentaerythritol tetra(meth)acrylate compounds; bisphenol type di(meth)acrylate compounds such as ethoxylated bisphenol A type di(meth)acrylate, propoxylated bisphenol A type di(meth)acrylate, propoxylated ethoxylated bisphenol A type di(meth)acrylate; be done.
Examples of (meth)acrylic compounds containing an alkyleneoxy group include, among others, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate and propoxylated ethoxylated bisphenol A di(meth)acrylate. is preferred, and ethoxylated bisphenol A type di(meth)acrylate is more preferred.

In one embodiment, the polymerizable compound may contain a thioether oligomer as a thiol compound and a (meth)allyl compound (preferably a polyfunctional (meth)allyl compound). In this case, the content of the (meth)allyl compound may be, for example, 10% by mass to 50% by mass, or 15% by mass to 45% by mass, relative to the total amount of the wavelength conversion resin composition. may be 20% by mass to 40% by mass.

When the polymerizable compound contains a thioether oligomer and a (meth) allyl compound as a thiol compound and the phosphor is a quantum dot phosphor, the quantum dot phosphor is dispersed in a silicone compound as a dispersion medium in the state of a dispersion There may be.

In one embodiment, the polymerizable compound is a thiol compound that is not in the state of a thioether oligomer, and a (meth)acrylic compound (preferably a polyfunctional (meth)acrylic compound, more preferably a bifunctional (meth)acrylic compound). may contain. In this case, the content of the (meth)acrylic compound may be, for example, 40% by mass to 90% by mass, or 60% by mass to 90% by mass, relative to the total amount of the wavelength conversion resin composition. may be 70% by mass to 85% by mass.

When the polymerizable compound contains a thiol compound that is not in the state of a thioether oligomer and a (meth) acrylic compound, and the phosphor is a quantum dot phosphor, the quantum dot phosphor is a (meth) acrylic compound as a dispersion medium. , preferably in a monofunctional (meth)acrylic compound, more preferably in isobornyl (meth)acrylate.

(Photoinitiator)
The photopolymerization initiator contained in the wavelength conversion resin composition is not particularly limited, and examples thereof include compounds that generate radicals upon irradiation with active energy rays such as ultraviolet rays.

Specific examples of photopolymerization initiators include benzophenone, N,N'-tetraalkyl-4,4'-diaminobenzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propanone-1,4,4′-bis(dimethylamino)benzophenone (also called “Michler ketone”), 4,4′-bis (Diethylamino)benzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 1-hydroxycyclohexylphenyl ketone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4- Aromatic ketone compounds such as (2-hydroxyethoxy)-phenyl)-2-hydroxy-2-methyl-1-propan-1-one and 2-hydroxy-2-methyl-1-phenylpropan-1-one; quinone compounds such as anthraquinone and phenanthrenequinone; benzoin compounds such as benzoin and alkylbenzoin; benzoin ether compounds such as benzoin alkyl ether and benzoin phenyl ether; benzyl derivatives such as benzyl dimethyl ketal; -diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-di(m-methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2,4-di(p-methoxyphenyl)-5-phenylimidazole dimer, 2-(2,4-dimethoxyphenyl)- 2,4,5-triarylimidazole dimers such as 4,5-diphenylimidazole dimer; acridine derivatives such as 9-phenylacridine and 1,7-(9,9′-acridinyl)heptane; 1,2 -octanedione 1-[4-(phenylthio)-2-(O-benzoyloxime)], ethanone 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1- oxime ester compounds such as (O-acetyloxime); coumarin compounds such as 7-diethylamino-4-methylcoumarin; thioxanthone compounds such as 2,4-diethylthioxanthone; 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2,4,6-trimethylbenzoyl- acylphosphine oxide compounds such as phenyl-ethoxy-phosphine oxide; The wavelength conversion resin composition may contain one type of photopolymerization initiator alone, or may contain two or more types of photopolymerization initiators in combination.

From the viewpoint of curability, the photopolymerization initiator is preferably at least one selected from the group consisting of acylphosphine oxide compounds, aromatic ketone compounds, and oxime ester compounds. At least one selected from the group consisting of more preferably an acylphosphine oxide compound.

The content of the photopolymerization initiator in the wavelength conversion resin composition is preferably, for example, 0.1% by mass to 5% by mass with respect to the total amount of the wavelength conversion resin composition, and is preferably 0.1% by mass. % to 3% by mass, more preferably 0.1% to 1.5% by mass. When the content of the photopolymerization initiator is 0.1% by mass or more, the sensitivity of the wavelength conversion resin composition tends to be sufficient, and the content of the photopolymerization initiator is 5% by mass or less. In this case, the effect on the hue of the wavelength conversion resin composition and the decrease in storage stability tend to be suppressed.

(other ingredients)
The wavelength conversion resin composition may further contain other components such as a liquid medium (organic solvent, etc.), a polymerization inhibitor, a silane coupling agent, a surfactant, an adhesion imparting agent, and an antioxidant. For each of the other components, the wavelength conversion resin composition may contain one type alone or may contain two or more types in combination.

-Light scattering layer-
The light scattering layer contains filler particles and a resin, and functions to scatter light incident on the light scattering layer.
From the viewpoint of increasing the amount of backscattered light, the surface of the light scattering layer preferably has projections caused by the filler particles. The surface of the projections caused by the filler particles may be coated with the resin contained in the light scattering layer, or the filler particles may be exposed.

From the viewpoint of improving the appearance of the wavelength conversion member, the average height of the projections caused by the filler particles is preferably 7 μm or less, more preferably 6 μm or less, and even more preferably 5 μm or less. The average height of the protrusions may be 0.5 μm or more.
The average height of convex portions caused by filler particles refers to a value measured with a laser microscope (objective lens x 20). The average height of the convex portions was calculated from the whole surface photograph (size: 650 μm×646 μm) taken with a laser microscope, and this value was taken as the average height of the convex portions caused by the filler particles.

The average thickness of the light scattering layer is not particularly limited. For example, it can be selected from between 0.1 μm and 70 μm. When the light-scattering layer is provided on the substrate, the average thickness of the light-scattering layer is the thickness of the portion excluding the substrate.

(filler particles)
The type of filler particles contained in the light-scattering layer is not particularly limited, and can be selected according to the desired properties of the light-scattering layer.

The average particle size of the filler particles may be 0.1 μm to 50 μm, 0.5 μm to 30 μm, 1.0 μm to 25 μm, or 1.5 μm to 22 μm. good. The average height of the projections caused by the filler particles can be adjusted by the average particle diameter of the filler particles.
The average particle size of the filler particles is measured in the same manner as the average particle size of the light scattering particles described above.

From the viewpoint of brightness, the refractive index of the filler particles is preferably 1.70 or less, more preferably 1.40 to 1.70, still more preferably 1.41 to 1.60, and particularly 1.42 to 1.50. preferable.

Filler particles include inorganic particles such as silica, alumina, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, titanium oxide, mica, kaolinite, pyrophyllite, acrylic resin, silicone resin, styrene. Resin particles such as resins, urea resins, phenol resins, epoxy resins, and benzoguanamine resins can be used. Among these, from the viewpoint of suppressing luminance loss, resin particles are preferable, and at least one kind of particles selected from the group consisting of acrylic resins and silicone resins is more preferable.
The filler particles may be used singly or in combination of two or more.

The proportion of the filler particles in the entire light scattering layer is 7% by mass to 50% by mass, preferably 15% by mass to 45% by mass, more preferably 25% by mass to 41% by mass.

(resin)
Resins contained in the light scattering layer include vinyl alcohol resin, polyester resin, polyvinyl chloride resin, polypropylene resin, polystyrene resin, polyethylene resin, acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene resin, (meth)acrylic resin, poly Thermosetting resins such as thermoplastic resins such as butylene terephthalate resins and polyethylene terephthalate resins, phenol resins, melamine resins, alkyd resins, epoxy resins, polyurethane resins and silicone resins can be used. Among these, thermoplastic resins are preferred from the viewpoint of workability, and vinyl alcohol resins are more preferred from the viewpoint of gas barrier properties.
Resin may be used individually by 1 type, and may use 2 or more types together.

If necessary, the light scattering layer may contain components other than filler particles and resin. Other components include curing agents, antifoaming agents, coatability improvers, thickeners, lubricants, antistatic agents, ultraviolet absorbers, antioxidants, foaming agents, dyes, pigments, and the like.

If desired, a light scattering layer may be formed over the substrate. The type of base material is not particularly limited, and can be selected from resins and the like. A coating material, which will be described later, may be used as the base material. When the coating material is used as the base material, it is preferable that the light scattering layer is arranged on the surface of the coating material opposite to the surface facing the wavelength conversion layer.

From the viewpoint of handleability, it is preferable that the light scattering layer is integrated with the wavelength conversion layer. In this case, an adhesive layer, a covering material, or the like may or may not be present between the light scattering layer and the wavelength conversion layer.
The details of the composition for forming a light scattering layer used for forming the light scattering layer will be described later.
In addition, when a substrate such as an adhesive layer or a coating material is present between the light scattering layer and the wavelength conversion layer, the light scattering layer may constitute a light scattering member together with the substrate. The light scattering member will be described later.

-covering material-
The wavelength conversion member may have a covering material that covers at least part of the wavelength conversion layer. The coating material may be arranged on at least one surface side of the wavelength conversion layer, for example. By arranging the covering material, the penetration of moisture, oxygen, etc. into the wavelength conversion layer is suppressed, and deterioration of the wavelength conversion layer is suppressed. In addition, the wavelength conversion member is imparted with appropriate rigidity to improve handleability.

The material of the coating material is not particularly limited, and polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefins such as polyethylene (PE) and polypropylene (PP), polyamides such as nylon, and ethylene-vinyl alcohol copolymers. Combined (EVOH) or the like may be used. From the standpoint of availability, polyethylene terephthalate is preferable as the material of the covering material.

The covering material preferably has barrier properties against at least one of oxygen and water, and more preferably has barrier properties against both oxygen and water. The covering material having a barrier property against at least one of oxygen and water may be one provided with a barrier layer (barrier film) for enhancing the barrier function against water, oxygen and the like. Examples of the barrier layer include inorganic layers containing inorganic substances such as alumina and silica. When the covering material has a barrier layer, it is preferable to have the barrier layer on the side of the covering material facing the wavelength conversion layer.

The oxygen permeability of the covering material is, for example, preferably 2.5 mL/(m ² 24 h MPa) or less, more preferably 2.2 mL/(m ² 24 h MPa) or less. It is more preferably 0 mL/(m ² ·24h·MPa) or less. The oxygen permeability of the dressing may be 0.5 mL/(m ² ·24h·MPa) or more. The oxygen transmission rate of the covering material can be measured using an oxygen transmission rate measuring device (eg, MOCON, OX-TRAN) under conditions of a temperature of 23° C. and a relative humidity of 90%.

In addition, the water vapor transmission rate of the covering material is, for example, preferably 1×10 ⁰ g/(m ² ·24 h) or less, more preferably 8×10 ⁻¹ g/(m ² ·24 h) or less. It is preferably 6×10 ⁻¹ g/(m ² ·24 h) or less. The coating material may have a water vapor transmission rate of 1×10 ⁻¹ g/(m ² ·24 h) or more. The water vapor transmission rate of the covering material can be measured using a water vapor transmission rate measuring device (for example, MOCON, AQUATRAN) under conditions of a temperature of 40° C. and a relative humidity of 100%.

The average thickness of the covering material is, for example, preferably 10 μm to 150 μm, more preferably 10 μm to 140 μm, even more preferably 10 μm to 130 μm.

-Wavelength selective transmission layer-
The wavelength conversion member of the present disclosure may further have a wavelength selective transmission layer.
Since the wavelength conversion member has the wavelength selective transmission layer, the light utilization efficiency tends to be improved without arranging the reflection member on the light source side of the backlight.

In the present disclosure, the "wavelength selective transmission layer" selectively reflects light emitted by the phosphor contained in the wavelength conversion layer (that is, compared to light of a wavelength other than the light emitted by the phosphor, high light reflectance).
The reason why the wavelength conversion member having the wavelength selective transmission layer is excellent in light utilization efficiency is as follows.
In the wavelength conversion member, part of the light (for example, blue light) incident on the wavelength conversion layer from the light source is converted into light of another wavelength (for example, red light or green light) by the phosphor.
When the wavelength selective transmission layer is arranged between the light source and the wavelength conversion layer, the wavelength of light transmitted from the light source through the wavelength selective transmission layer and incident on the wavelength conversion layer is converted by the phosphor in the wavelength conversion layer. be. Since the wavelength-converted light emitted from the phosphor travels not only in the direction of incidence on the wavelength conversion layer but also in all directions, a part of the light does not travel to the image display surface side, resulting in loss.
When the wavelength conversion member has the wavelength selective transmission layer, the light emitted by the phosphor, which is directed toward the light source, is reflected by the wavelength selective transmission layer, and the direction of travel changes toward the image display surface. As a result, the loss of light emitted by the phosphor is reduced, and good utilization efficiency is maintained.

When the wavelength conversion member has the wavelength selective transmission layer and the light scattering layer, the positional relationship between the wavelength selective transmission layer and the light scattering layer is not particularly limited.
From the viewpoint of enhancing the efficiency of light utilization, it is preferable that the wavelength selective transmission layer is arranged at least between the light source and the wavelength conversion layer.
From the viewpoint of suppressing luminance unevenness, the light scattering layer is preferably arranged at least between the wavelength conversion layer and the image display surface (that is, on the side opposite to the light source).

The number of wavelength selective transmission layers and light scattering layers in the wavelength conversion member is not particularly limited, and may be one or more.

The wavelength selective transmission layer selectively reflects light emitted by the phosphor contained in the wavelength conversion layer. For example, the reflectance for light emitted by the phosphor may be 50% or more.
The reflectance is a value at the maximum value (at least one of the maximum values if there are multiple maximum values) of the wavelength spectrum of the light emitted by the phosphor.
Specifically, the reflectance can be measured by the following method. Using a multi-angle variable spectrometer (eg, Agilent Technology, Cary7000), light is incident on the wavelength selective transmission layer at an incident angle of 0°, and the spectrum of specularly reflected light reflected by the wavelength selective transmission layer is measured in a wavelength range of 300 nm to 300 nm. Measurement is performed at 800 nm and wavelength intervals of 1 nm.

From the viewpoint of increasing the utilization efficiency of light emitted by the light source, the wavelength selective transmission layer preferably transmits light incident on the wavelength conversion layer from the light source. For example, the transmittance of light incident on the wavelength conversion layer from the light source may be 50% or more.
The transmittance is a value at the maximum value (at least one of the maximum values if there are multiple maximum values) of the wavelength spectrum of light incident on the wavelength conversion layer from the light source.
Specifically, the transmittance can be measured by the following method. Using a multi-angle variable spectrometer (for example, Agilent Technology, Cary7000), light is incident on the wavelength selective transmission layer at an incident angle of 0°, and the spectrum of the light transmitted through the wavelength selective transmission layer is measured in the wavelength range of 300 nm to 800 nm. Measurement is performed with a wavelength interval of 1 nm.

From the viewpoint of increasing the utilization efficiency of the light emitted by the phosphor, the reflectance of the wavelength selective transmission layer for the light emitted by the phosphor may be 60% or more, 70% or more, or 80% or more. There may be.

From the viewpoint of increasing the utilization efficiency of light incident on the wavelength conversion layer from the light source, the transmittance of the wavelength selective transmission layer for light incident on the wavelength conversion layer from the light source may be 60% or more, or 70% or more. may be 80% or more.

In one embodiment, the reflectance of the wavelength selective transmission layer for light emitted by the phosphor may be reflectance for light with a wavelength of 500 nm to 780 nm.
In one embodiment, the transmittance of the wavelength selective transmission layer for light incident on the wavelength conversion layer from the light source may be the transmittance for light with a wavelength of 400 nm to 480 nm.

The configuration of the wavelength selective transmission layer is not particularly limited, and it may be produced by a known method. For example, a laminate in which a layer A having a thickness of 1/4 of the wavelength of light to be reflected (wavelength to be reflected) and a layer B having the same thickness as the layer A but having a different refractive index are alternately arranged. good too. By adjusting the number of layers included in the laminate, a wavelength selective transmission layer having a desired reflectance can be obtained. For example, the number of layers included in the laminate may be selected from between 100 and 2000.
When there are a plurality of wavelengths to be reflected, a wavelength selective transmission layer may be formed by combining a plurality of laminates having different wavelengths to be reflected.

The material of the wavelength selective transmission layer is not particularly limited, and can be selected from organic materials such as resins, inorganic materials such as metals, metal oxides, and metal nitrides. If necessary, the wavelength selective transmission layer may contain additives such as light diffusing particles, pigments, dyes, lubricants, light stabilizers, heat stabilizers, flame retardants, ultraviolet absorbers, curing agents and cross-linking agents.

From the viewpoint of handleability, it is preferable that the wavelength selective transmission layer is integrated with the wavelength conversion layer. In this case, an adhesive layer, a coating material, or the like may or may not be present between the wavelength selective transmission layer and the wavelength conversion layer.

The thickness of the wavelength selective transmission layer is not particularly limited. For example, it can be selected from between 20 μm and 100 μm.

(Configuration example of wavelength conversion member)
FIG. 1 shows a configuration example of the wavelength conversion member. However, the wavelength conversion member of the present disclosure is not limited to the configuration shown in each figure. In addition, the thickness of each layer in each drawing is conceptual, and the relative relationship between the thicknesses is not limited to this. Although FIG. 1 shows a configuration example of a wavelength conversion member having a wavelength selective transmission layer, the wavelength conversion member may not have the wavelength selective transmission layer. In addition, the same reference numerals are given to those having substantially the same functions throughout the drawings, and the description thereof may be omitted.

A wavelength conversion member 10A shown in FIG. 1A includes a wavelength conversion layer 11, a coating material 12A provided on the image display surface side of the wavelength conversion layer 11, and a coating material 12B provided on the light source side of the wavelength conversion layer 11. have Further, it has a light scattering layer 13 provided on the opposite side of the coating material 12A from the wavelength conversion layer 11 side, and a wavelength selective transmission layer 14 provided on the opposite side of the coating material 12B from the wavelength conversion layer 11 side. An adhesive layer 15 is provided between the wavelength selective transmission layer 14 and the covering material 12B.

In the wavelength conversion member 10B shown in FIG. 1B, the light scattering layer 13 is provided on the opposite side of the base material 16 to the wavelength conversion layer 11 side, and the adhesive layer 15 is provided between the base material 16 and the coating material 12A. is provided, which is different from the wavelength conversion member 10A.

In the wavelength conversion member 10C shown in FIG. 1C, the light scattering layer 13 is provided on the side of the coating material 12A opposite to the wavelength conversion layer 11 side and also on the side of the coating material 12B opposite to the wavelength conversion layer 11 side. is different from the wavelength conversion member 10A in that

In the wavelength conversion member 10D shown in FIG. 1D, the light scattering layer 13 is arranged directly on the wavelength conversion layer 11 without the coating material 12A, and the wavelength selective transmission layer 14 is arranged without the coating material 12B. It is different from the wavelength conversion member 10A in that it is arranged directly on the opposite side of the conversion layer 11 to the light scattering layer 13 side. In this case, the light scattering layer 13 may serve as the covering material 12A, and the wavelength selective transmission layer 14 may serve as the covering material 12B.

<Method for manufacturing wavelength conversion member>
A method for manufacturing the wavelength conversion member is not particularly limited. A method for manufacturing the wavelength conversion member will be described below with reference to FIG.

In the wavelength conversion member shown in FIG. 1, the configuration in which the coating material 12A and the coating material 12B are provided on both sides of the wavelength conversion layer 11 (FIGS. 1A, 1B and 1C) is, for example, , can be produced by the following method. Hereinafter, the structure in which the coating material 12A and the coating material 12B are provided on both sides of the wavelength conversion layer 11 may be referred to as a wavelength conversion member main body.

First, a coating film is formed by applying a wavelength-converting resin composition to the surface of a continuously conveyed film-like coating material (hereinafter also referred to as "first coating material"). The method of applying the wavelength-converting resin composition is not particularly limited, and examples thereof include a die coating method, a curtain coating method, an extrusion coating method, a rod coating method, and a roll coating method.

Next, a continuously conveyed film-like covering material (hereinafter, also referred to as “second covering material”) is adhered onto the coating film of the wavelength-converting resin composition.

Next, by irradiating an active energy ray from the side of the first coating material or the second coating material that is permeable to the active energy ray, the coating film is cured to form a cured product layer. After that, by cutting into a specified size, a laminated body in which the coating material 12A and the coating material 12B are provided on both sides of the wavelength conversion layer 11 can be obtained.
The wavelength and irradiation dose of the active energy ray can be set according to the composition of the wavelength conversion resin composition, the thickness of the wavelength conversion layer, and the like. In one embodiment, UV radiation with a wavelength of 280 nm to 400 nm is applied at a dose of 100 mJ/cm ² to 5000 mJ/cm ² . Ultraviolet light sources include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and the like.

In addition, when neither the first coating material nor the second coating material can transmit the active energy ray, the coating film is irradiated with the active energy ray before bonding the second coating material, and the cured product layer may be formed.
In the wavelength conversion member shown in FIG. 1, the configuration in which the coating material 12A and the coating material 12B are not provided on both sides of the wavelength conversion layer 11 (FIG. 1(D)) is, for example, a temporary support such as a resin film. , the wavelength conversion resin composition is applied as described above, cured to form the wavelength conversion layer 11 on the temporary support, and then the wavelength conversion layer 11 is peeled off from the temporary support. .

In FIG. 1A, the light scattering layer 13 is arranged on one side of the wavelength conversion member main body. Further, in FIG. 1C, light scattering layers 13 are arranged on both surface sides of the wavelength conversion member body. Further, in FIG. 1D, a light scattering layer 13 is arranged on one side of the wavelength conversion layer 11 .
The light scattering layer 13 in FIG. 1(A) or FIG. 1(D) is obtained, for example, by applying the composition for forming a light scattering layer of the present disclosure to one side of the wavelength conversion layer 11 (or the wavelength conversion member main body). Alternatively, a coating film may be formed by drying the coating film.
In the wavelength conversion member 10C of FIG. 1C, for example, the composition for forming a light scattering layer of the present disclosure is applied to one surface side of the wavelength conversion member main body to form a coating film, and the coating film is dried. to form the first light scattering layer 13 on one side of the wavelength conversion member main body. Next, the composition for forming a light scattering layer of the present disclosure is applied to the other surface side of the wavelength conversion member main body to form a coating film, the coating film is dried, and the second surface is applied to the other surface side of the wavelength conversion member main body. 2 light scattering layer 13 is formed. Thus, two light scattering layers 13 in FIG. 1(C) may be formed.

In FIG. 1B, the light scattering layer 13 is arranged on one side of the wavelength conversion member main body with the adhesive layer 15 and the base material 16 interposed therebetween. The substrate 16 and the light scattering layer 13 in FIG. 1B may be the light scattering member of the present disclosure, which will be described later. In the wavelength conversion member 10B of FIG. 1B, if the light scattering member of the present disclosure is arranged on one surface side of the wavelength conversion member main body so that the surface on the substrate 16 side faces the wavelength conversion member main body, good. In this case, the surface of the light scattering member of the present disclosure on the substrate 16 side or one surface of the wavelength conversion member main body is provided with an adhesive that constitutes the adhesive layer 15, and the light scattering member of the present disclosure and the wavelength conversion member main body are attached. may be bonded together to obtain the wavelength conversion member 10B of FIG. 1(B).

In FIGS. 1A and 1B, a wavelength selective transmission layer 14 is arranged on one surface side of the wavelength conversion member body with an adhesive layer 15 interposed therebetween. Further, in FIG. 1C, a wavelength selective transmission layer 14 is arranged on one side of the wavelength conversion member main body with a light scattering layer 13 and an adhesive layer 15 interposed therebetween. Further, in FIG. 1D, a wavelength selective transmission layer 14 is arranged on one side of the wavelength conversion layer 11 .
In the wavelength conversion member 10A of FIG. 1A, the wavelength conversion member 10B of FIG. 1B, or the wavelength conversion member 10C of FIG. 15 may be used to adhere to one side of the wavelength conversion member main body.
In the wavelength conversion member 10D shown in FIG. 1D, the wavelength selective transmission layer 14 may be formed directly on one surface of the wavelength conversion layer 11. As shown in FIG. A known method can be used to form the wavelength selective transmission layer 14 .

<Composition for forming light scattering layer>
The composition for forming a light scattering layer of the present disclosure contains filler particles, a resin, and a solvent, and the ratio of the filler particles to the total solid content is 7% by mass to 50% by mass. .
The composition for forming a light scattering layer of the present disclosure contains filler particles, a resin, and a solvent, and if necessary, a curing agent, an antifoaming agent, a coatability improver, a thickener, a lubricant, and an antistatic agent. Other ingredients such as agents, UV absorbers, antioxidants, blowing agents, dyes, pigments, etc. may also be included.
Specific examples of the filler particles and resin contained in the composition for forming a light scattering layer of the present disclosure are the same as those of the filler particles and resin used in the light scattering layer.
The ratio of the filler particles to the total solid content of the composition for forming a light scattering layer is 7% by mass to 50% by mass, preferably 15% by mass to 45% by mass, more preferably 25% by mass to 41% by mass.
In the present disclosure, the “solid content” of the light-scattering layer-forming composition means the components of the light-scattering layer-forming composition excluding volatile components.
The type of solvent is not particularly limited, and can be appropriately selected in consideration of the types of filler particles and resin, solubility in solvent, dispersibility, and the like. Water, an organic solvent, etc. are mentioned as a solvent.

<Light scattering member>
The light scattering member of the present disclosure has a base material and a light scattering layer containing filler particles and a resin and arranged on one side of the base material, and the ratio of the filler particles to the entire light scattering layer. is 7% by mass to 50% by mass.
Specific examples of the filler particles and resin used in the light-scattering member of the present disclosure and preferred ranges of the content of the filler particles are the same as those of the filler particles and resin used in the light-scattering layer.
The light-scattering member of the present disclosure may have other constituent elements such as an adhesive layer and a primer layer. When the light-scattering member has an adhesive layer, the adhesive layer is preferably provided on the surface of the substrate opposite to the surface on which the light-scattering layer is provided.
Components contained in the adhesive layer are not particularly limited, and components known as adhesive components may be used. Examples of the base resin of the adhesive component include acrylic resins, various synthetic rubbers, natural rubbers, and the like.
In order to improve the adhesion between the base material and the adhesive layer, the surface of the base material on which the adhesive layer is provided may be chemically or physically treated as necessary. The surface treatments include, for example, corona treatment, chromic acid treatment, ozone exposure, flame exposure, high voltage shock exposure, and ionizing radiation treatment.
The base material contained in the light scattering member may be the same material as or different from the above-described coating material constituting the wavelength conversion member, and is not particularly limited.

From the viewpoint of ensuring sufficient brightness of the wavelength conversion member, the total light transmittance of the light scattering member is preferably 65% or more, more preferably 70% or more, and further preferably 75% or more. Preferably, 90% or more is particularly preferred. The total light transmittance of the light scattering member may be 100% or less. The total light transmittance of the light scattering member is obtained in the same manner as the total light transmittance of the wavelength conversion member.
From the viewpoint of suppressing luminance unevenness of the wavelength conversion member, the haze of the light scattering member is preferably 25% or more, more preferably 30% or more, and even more preferably 35% or more. The haze of the light scattering member may be 100% or less. The haze of the light scattering member is determined in the same manner as the haze of the wavelength conversion member.

A method for forming the light scattering layer is not particularly limited. For example, the composition for forming a light-scattering layer of the present disclosure may be applied onto a substrate to form a coating film, and the coating film may be dried to form a light-scattering layer.
In this case, the composition for forming a light-scattering layer is applied to the surface of a continuously conveyed film-like substrate to form a coating film. The method of applying the light-scattering layer-forming composition is not particularly limited, and includes die coating, curtain coating, extrusion coating, rod coating, roll coating, and the like.
Drying conditions for the coating film are not particularly limited. The coating film may be dried by heating. Drying temperatures include 60°C to 120°C. Drying times include 1.5 minutes to 5 minutes.

<Backlight unit>
A backlight unit of the present disclosure has a light source and a wavelength conversion member of the present disclosure.

From the viewpoint of improving color reproducibility, the backlight unit preferably has a multi-wavelength light source. As a preferred embodiment, blue light having an emission center wavelength in a wavelength range of 430 nm to 480 nm and an emission intensity peak with a half width of 100 nm or less, and an emission center wavelength in a wavelength range of 520 nm to 560 nm, A backlight that emits green light having an emission intensity peak with a half-value width of 100 nm or less, and red light having an emission center wavelength in a wavelength range of 600 nm to 680 nm and an emission intensity peak with a half-value width of 100 nm or less. A light unit may be mentioned. The half width of the emission intensity peak means the peak width at half the peak height.

From the viewpoint of further improving color reproducibility, the central emission wavelength of blue light emitted by the backlight unit is preferably in the range of 440 nm to 475 nm. From the same point of view, the emission center wavelength of the green light emitted by the backlight unit is preferably in the range of 520 nm to 545 nm. From the same point of view, it is preferable that the emission center wavelength of the red light emitted by the backlight unit is in the range of 610 nm to 640 nm.

In addition, from the viewpoint of further improving color reproducibility, the half width of each emission intensity peak of blue light, green light, and red light emitted by the backlight unit is preferably 80 nm or less, and 50 nm or less. It is more preferable to have

As the light source of the backlight unit, for example, a light source that emits blue light having an emission central wavelength in the wavelength range of 430 nm to 480 nm can be used. Examples of light sources include LEDs (Light Emitting Diodes) and lasers. When using a light source that emits blue light, the wavelength conversion member preferably contains at least a phosphor R that emits red light and a phosphor G that emits green light. Thereby, white light can be obtained from the red light and green light emitted from the wavelength conversion member and the blue light transmitted through the wavelength conversion member.

As the light source of the backlight unit, for example, a light source that emits ultraviolet light having an emission central wavelength in the wavelength range of 300 nm to 430 nm can be used. Light sources include, for example, LEDs and lasers. When a light source that emits ultraviolet light is used, the wavelength conversion member preferably contains phosphor B, which is excited by excitation light and emits blue light, together with phosphor R and phosphor G. Thereby, white light can be obtained from red light, green light, and blue light emitted from the wavelength conversion member.

The backlight unit of the present disclosure may be edge-lit or direct-lit. From the viewpoint of thinning the backlight unit, the direct type is preferable.

FIG. 2 shows an example of a schematic configuration of a direct type backlight unit. However, the backlight unit of the present disclosure is not limited to the configuration of FIG. 2 . In addition, the sizes of the members in FIG. 2 are conceptual, and the relative relationship between the sizes of the members is not limited to this.

The backlight unit 20 shown in FIG. 2 includes a light source 21 that emits blue light _LB , a light diffusing plate 22, a wavelength conversion member 10, and the light source 21 and the light diffusing plate 22 facing each other with the wavelength converting member 10 interposed therebetween. and a retroreflective member 23 that is
The light diffusing plate 22 may be omitted, a plurality of plates may be provided, or the light diffusing plate 22 may be arranged directly above the wavelength conversion layer 10 (on the side opposite to the light source 21). Retroreflective member 23 includes, for example, a reflective polarizer layer and a microstructured layer.
The wavelength conversion member 10 emits red light L _R and green light L _G using part of the blue light L _B as excitation light, and red light L _R and green light L _G and blue light L that did not become excitation light. _B is emitted. White light LW is emitted from the retroreflective member 23 by the red light L _R , green light L _G , and blue _light L _B .

<Image display device>
The image display device of the present disclosure includes the backlight unit of the present disclosure described above. The image display device is not particularly limited, and examples thereof include a liquid crystal display device.

FIG. 3 shows an example of a schematic configuration of a liquid crystal display device. However, the liquid crystal display device of the present disclosure is not limited to the configuration of FIG. Also, the sizes of the members in FIG. 3 are conceptual, and the relative relationship between the sizes of the members is not limited to this.

A liquid crystal display device 30 shown in FIG. 3 includes a backlight unit 20 and a liquid crystal cell unit 31 arranged to face the backlight unit 20 . The liquid crystal cell unit 31 is configured such that the liquid crystal cell 32 is arranged between the polarizing plate 33A and the polarizing plate 33B.

The driving method of the liquid crystal cell 32 is not particularly limited, and may be a TN (Twisted Nematic) method, an STN (Super Twisted Nematic) method, a VA (Vertical Alignment) method, an IPS (In-Plane-Switching) method, or an OCB (Optically Compensated Birefringence) method. methods and the like.

EXAMPLES The present disclosure will be specifically described below with reference to Examples, but the present disclosure is not limited to these Examples.

(Preparation of composition for forming light scattering layer)
Each component shown in Table 1 was mixed in water in the amount (unit: part by mass) shown in the same table. At that time, the amount of water was adjusted so that the solid content concentration was 10% by mass. Light-scattering layer-forming compositions of Examples 1 to 6 and Comparative Examples 4 to 6 were prepared. "-" in Table 1 means unblended. Incidentally, in Comparative Examples 1 to 3, no light scattering member was used.
In addition, the abbreviations of the components in Table 1 mean the following components.
・BvOH: butenediol/vinyl alcohol copolymer resin (product name: Nichigo G-Polymer AZF8035W, Mitsubishi Chemical Corporation, degree of saponification: 99 mol%, degree of polymerization: 300)
・ Metal-based curing agent: Zirconium acetate (product name: Zircosol ZA-20, Daiichi Kigenso Kagaku Kogyo Co., Ltd.)
・ Acrylic resin particles 1: KMR-3TA (product name), Soken Chemical Co., Ltd., average particle size 3 μm, refractive index: 1.49
・ Acrylic resin particles 2: MR-7GC (product name), Soken Chemical Co., Ltd., average particle size 6 μm, refractive index: 1.49
・ Acrylic resin particles 3: MZ20-NH (product name), Soken Chemical Co., Ltd., average particle size 20 μm, refractive index: 1.49
・ Silicone resin particles: KMP-701 (product name), Shin-Etsu Chemical Co., Ltd., average particle size 3.5 μm, refractive index: 1.43
・ Alumina particles, AA-1.5 (product name), Sumitomo Chemical Co., Ltd., average particle size 1.6 μm, refractive index: 1.77

(Formation of light scattering member)
Using a comma coater, the composition for forming a light-scattering layer was applied to the side of the substrate described below opposite to the side on which the adhesive layer was provided. After that, it was dried for 3 minutes in a hot air convection dryer at 100° C. to remove water, and a light scattering layer composed of the composition for forming a light scattering layer was formed. got the parts. The average thickness of the light scattering layer for each light scattering member was 8 μm. The average height of the convex portions of each light scattering member was obtained by the method described above using a laser microscope (LEXT OLS4100 manufactured by Olympus Corporation, objective lens ×20). Table 1 shows the results obtained.
As the substrate, the substrate A was used in Examples 1 to 5 and Comparative Examples 4 to 5, and the substrate B was used in Example 6 and Comparative Example 6.
・ Base material A: Cosmoshine (registered trademark) A4300 (product name) Toyobo Co., Ltd. (average thickness: 38 μm PET film)
・ Base material B: Emblet S50 (product name) Unitika Ltd. (average thickness: 50 μm PET film)

(Preparation of wavelength conversion resin composition)
A wavelength conversion resin composition was prepared by mixing the following components.
As a polyfunctional (meth)acrylate, tricyclodecane dimethanol diacrylate (Evans, SR833NS) 71.9 parts As a polyfunctional thiol compound, pentaerythritol tetrakis (3-mercaptopropionate) (SC Organic Chemical Co., Ltd., PEMP) 17.4 parts by mass As a monofunctional thiol compound, 3-mercaptopropionic acid (Tokyo Chemical Industry Co., Ltd., M0061) 3.5 parts by mass As a photopolymerization initiator, 2,4,6-trimethylbenzoyl-diphenyl-phosphine Oxide (BASF, IRGACURE TPO) 0.5 parts by mass As a green-emitting phosphor, a quantum dot phosphor dispersion (Nanosys, InP/ZnS (core/shell) dispersion, Gen3.0 QD Concentrate, dispersant: iso Bornyl acrylate, dispersant content: 90% by mass or more) 4.7 parts by mass Quantum dot phosphor dispersion (Nanosys, InP/ZnS (core/shell) dispersion, Gen3.0 QD Concentrate) as red-emitting phosphor , dispersant: isobornyl acrylate, dispersant content: 90% by mass or more) 1.7 parts by mass As light scattering particles, titania particles (Chemours, R-706, refractive index 2.50, average particle diameter 0.50) 36 μm) 0.33 parts by mass

(Manufacture of wavelength conversion member)
The wavelength conversion resin composition obtained above was applied onto the inorganic barrier layer of the coating material C described below to form a coating film. On this coating film, the following coating material C is laminated in such a state that the surface of the coating material C on the inorganic barrier layer side is in contact with the coating film, and is irradiated with ultraviolet rays using an ultraviolet irradiation device (Eigraphics Co., Ltd.). Amount: 1000 mJ/cm ² ) to obtain a wavelength conversion member main body in which barrier layers are arranged on both sides of a cured layer (that is, a wavelength conversion layer) containing a cured wavelength conversion resin. The average thickness of the cured product layer was 57 µm.
Coating Material C: Barrier film having an inorganic barrier layer on PET-12 (product name) Unitika Ltd. (average thickness: 12 μm) The inorganic barrier layer was formed by the following method. In a high-frequency sputtering apparatus, high-frequency power with a frequency of 13.56 MHz and a power of 5 kW is applied to the electrodes to generate discharge in the chamber, and a target material (silica) with a thickness of 50 nm is formed on one side of a polyethylene terephthalate film. A silica deposition layer was formed as an inorganic barrier layer having a refractive index of 1.46.
The water vapor transmission rate for Dressing C was 0.22 g/(m ² ·24 h) and the oxygen transmission rate was 1.8 mL/(m ² ·24 h·MPa).

A wavelength selective transmission layer was adhered to the light source side surface of the obtained wavelength conversion member main body using an adhesive. In this case, the column of the wavelength selective transmission layer in Table 1 was set to "present".
As the wavelength selective transmission layer, an alternate laminate of polyethylene naphthalate layers and polymethyl methacrylate layers having a reflectance of 85% or more for light with a wavelength of 500 nm to 780 nm and a transmittance of 80% or more for light with a wavelength of 400 nm to 480 nm. (average thickness 55 μm) was used.
Further, an adhesive is applied to the surface of the light scattering member obtained as described above opposite to the surface on which the light scattering layer is provided, and each A light scattering member was attached. When the light-scattering member was attached, the column of the light-scattering member in Table 1 was indicated as "present".
In addition, in Comparative Example 1, no light scattering member was attached. In Comparative Example 2, the substrate A was attached instead of the light scattering member. In Comparative Example 3, a substrate B was attached instead of the light scattering member. In Table 1, the column for the light-scattering member of Comparative Examples 1-3 is "none".
Thus, a wavelength conversion member was obtained.

<Evaluation>
Using the obtained wavelength conversion member and light scattering member, the following evaluation was carried out.
- Measurement of total light transmittance and haze -
The total light transmittance and haze value of the light scattering member obtained as described above were measured using a haze meter (NDH7000SP, Nippon Denshoku Industries Co., Ltd.). Table 1 shows the results.
Specifically, the light scattering member was installed in the light irradiation part of the haze meter, and white light was incident thereon. Parallel light transmittance and diffuse transmittance were measured by opening and closing the white plate in the built-in integrating sphere. The total light transmittance and haze value were obtained using the following formulas.
[Total light transmittance]=[parallel light transmittance]+[diffuse transmittance] (1)
[Haze]=[diffuse transmittance]/[total light transmittance]×100 (2)

- Luminance measurement -
A backlight in which a blue LED (wavelength: 448 nm) is arranged on a light diffusion plate and a light reflection plate is installed on the wavelength selective transmission layer side of the wavelength conversion member, and a retroreflective member is installed on the viewing surface side to emit light. A radiance evaluation system was constructed.
The distance between the light diffusing plate and the LEDs was set to 20 mm, and the LEDs were arranged at positions corresponding to intersections of a grid pattern of 50 mm x 60 mm on the light reflecting plate.
Luminance (cd/m ² ) was measured using the above evaluation system with an observation angle of 2°. Measurement was performed using a multispectral radiance meter (PR-740 or PR-655, PHOTO RESEARCH). Using the wavelength conversion member of Comparative Example 1 as a reference, the luminance of the wavelength conversion member of Comparative Example 1 and the luminance of the wavelength conversion members of the other Examples or Comparative Examples were measured with the same model of multi-spectral radiance meter. Taking the luminance of the wavelength conversion member of Comparative Example 1 as 100%, the relative values of the luminance of the wavelength conversion members of other examples or comparative examples were obtained. When the relative value of luminance was 95% or more, it was evaluated as A, and when the relative value of luminance was less than 95%, it was evaluated as B. Table 1 shows the results.
For Comparative Example 1, luminance was measured with PR-740 and PR-655. For Comparative Examples 4 and 5, luminance was measured with PR-740. For Example and Comparative Example 6, luminance was measured with PR-655.

-exterior-
The appearance of the surface of the wavelength conversion member to which the light scattering member was attached was visually observed, and the appearance of the wavelength conversion member was evaluated according to the following criteria. Table 1 shows the results.
A: During the coating of the composition for forming a light-scattering layer, no streaks, coating unevenness, or aggregates are observed.
B: During the coating of the composition for forming a light-scattering layer, any of streaks, coating unevenness, and aggregates is observed.

-Measurement of Δy-
A two-dimensional luminance meter (product name: SR-5000, Topcon Technohouse Co., Ltd.) was used to measure Δy. A wavelength conversion member, which is a measurement sample, was placed on the LED light source, chromaticity y was obtained at five points each directly above the LED and between the LEDs, and the difference between the maximum value and the minimum value of chromaticity y was defined as Δy. Table 1 shows the results.
A light diffusion plate was placed below the wavelength conversion member, and a BEF (Brightness Enhancement Film) plate was placed above the wavelength conversion member.

From the evaluation results in Table 1, it can be seen that the wavelength conversion members of Examples can suppress the occurrence of LED unevenness and the decrease in brightness. Moreover, since it is not necessary to add a light diffusion plate for suppressing LED unevenness, it is possible to suppress an increase in the thickness of the wavelength conversion member.

10, 10A, 10B, 10C, 10D wavelength conversion member 11 wavelength conversion layer 12A, 12B coating material 13 light scattering layer 14 wavelength selective transmission layer 15 adhesive layer 16 substrate 20 backlight unit 21 light source 22 light diffusion plate 23 retroreflection Member 30 Liquid crystal display device 31 Liquid crystal cell unit 32 Liquid crystal cells 33A and 33B Polarizing plate

Claims (21)

A wavelength conversion layer containing a phosphor, and a light scattering layer containing filler particles and a resin disposed on at least one side of the wavelength conversion layer,
The wavelength conversion member, wherein the filler particles account for 7% by mass to 50% by mass of the entire light scattering layer. 2. The wavelength conversion member according to claim 1, wherein the surface of the light scattering layer has projections caused by the filler particles. 3. The wavelength conversion member according to claim 2, wherein the average height of the projections is 7 [mu]m or less. The wavelength conversion member according to any one of claims 1 to 3, wherein the filler particles have a refractive index of 1.70 or less. The wavelength conversion member according to any one of claims 1 to 4, wherein the filler particles are particles of at least one selected from the group consisting of acrylic resins and silicone resins. The wavelength conversion member according to any one of claims 1 to 5, wherein the phosphor contains a quantum dot phosphor. The quantum dot phosphor is a first quantum dot phosphor that converts light of 430 nm to 480 nm into light of 520 nm to 560 nm, and a second quantum dot phosphor that converts light of 430 nm to 480 nm into light of 600 nm to 680 nm. The wavelength conversion member according to claim 6 including at least one of. 8. Any one of claims 1 to 7, wherein the wavelength conversion layer contains light scattering particles, and the content of the light scattering particles is 0.5% by mass to 20% by mass with respect to the entire wavelength conversion layer. 1. The wavelength conversion member according to claim 1. 9. The wavelength conversion member according to claim 8, wherein the light scattering particles are at least one kind of particles selected from the group consisting of acrylic resin, silicone resin, zirconia, alumina, titanium oxide and silica. 10. The wavelength conversion member according to any one of claims 1 to 9, further comprising a covering material that covers at least part of the wavelength conversion layer. 11. The wavelength conversion member according to claim 10, wherein the coating material has an average thickness of 10 μm to 150 μm. The wavelength conversion member according to claim 10 or 11, wherein the coating material has barrier properties against at least one of oxygen and water. 13. The wavelength conversion member according to any one of claims 10 to 12, wherein the light scattering layer is arranged on the surface of the coating material opposite to the surface facing the wavelength conversion layer. 14. The wavelength conversion member according to any one of claims 1 to 13, further comprising a wavelength selective transmission layer. The wavelength conversion member according to any one of claims 1 to 14, wherein the wavelength conversion layer has an average thickness of 40 µm to 120 µm. A backlight unit comprising the wavelength conversion member according to any one of claims 1 to 15 and a light source. An image display device comprising the backlight unit according to claim 16 . having a base material and a light scattering layer containing filler particles and a resin and disposed on one side of the base material;
The light-scattering member, wherein the filler particles account for 7% by mass to 50% by mass of the entire light-scattering layer. Containing filler particles, a resin, and a solvent,
A composition for forming a light-scattering layer, wherein the filler particles account for 7% by mass to 50% by mass of the total solid content. A wavelength conversion member comprising disposing the light scattering member according to claim 18 on at least one surface side of a wavelength conversion layer containing a phosphor so that the surface on the substrate side faces the wavelength conversion layer. Production method. applying the composition for forming a light scattering layer according to claim 19 to at least one surface side of the wavelength conversion layer containing a phosphor to form a coating film;
A method for producing a wavelength conversion member, including drying the coating film.

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