JP2022174609A - Wavelength conversion member, backlight unit, and image display device - Google Patents

Abstract

To provide a wavelength conversion member which offers less in-plane variations in optical properties.SOLUTION: A wavelength conversion member provided herein comprises a wavelength conversion layer containing a phosphor and having an average thickness of 80 μm or less. A ratio of a difference between the maximum thickness and the minimum thickness of the wavelength conversion layer to the average thickness thereof is in a range of 0.01 to 0.1.SELECTED DRAWING: None

Description

The present disclosure relates to wavelength conversion members, backlight units, and image display devices.

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 and Patent Document 2).

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.

Japanese Patent Application Publication No. 2013-544018 WO2016/052625

In recent years, there has been an increasing demand for wavelength conversion members used in thin image display devices such as mobile electronic devices. As the image display device becomes thinner, the thickness of the wavelength conversion member itself tends to become thinner. Also, the wavelength conversion member used in mobile electronic devices is smaller than the wavelength conversion member used in large-screen televisions, large-sized liquid crystal displays, and the like. As for a small wavelength conversion member, since a plurality of wavelength conversion members are cut out from a raw sheet, it is necessary to ensure equivalent optical characteristics for all of these wavelength conversion members.
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 with less in-plane variation in optical properties, and a backlight unit and an image display device including the wavelength conversion member. intended to provide

Specific means for achieving the above object are as follows.
<1> having a wavelength conversion layer containing a phosphor,
The average thickness of the wavelength conversion layer is 80 μm or less,
A wavelength conversion member, wherein the ratio of the difference between the maximum thickness and the minimum thickness of the wavelength conversion layer to the average thickness of the wavelength conversion layer is 0.01 to 0.1.
<2> The wavelength conversion member according to <1>, wherein the phosphor contains a quantum dot phosphor.
<3> 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 <2>, containing at least one dot phosphor.
<4> 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> to <3> The wavelength conversion member according to any one of the items.
<5> The wavelength conversion member according to <4>, 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.
<6> The wavelength conversion member according to any one of <1> to <5>, which has a covering material covering at least part of the wavelength conversion layer.
<7> The wavelength conversion member according to <6>, wherein the coating material has an average thickness of 10 μm to 150 μm.
<8> The wavelength conversion member according to <6> or <7>, wherein the coating material has a barrier property against at least one of oxygen and water.
<9> The wavelength conversion member according to any one of <6> to <8>, wherein the coating material has a light scattering layer.
<10> The wavelength conversion member according to any one of <1> to <9>, further comprising a wavelength selective transmission layer.
<11> A backlight unit comprising the wavelength conversion member according to any one of <1> to <10> and a light source.
<12> An image display device comprising the backlight unit according to <11>.

According to one aspect of the present disclosure, there are provided a wavelength conversion member with little in-plane variation in optical properties, and a backlight unit and an image display device including this wavelength conversion member.

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 term "process" includes a process that is independent of other processes, and even if the purpose of the process is achieved even if it cannot be clearly distinguished from other processes. .
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) acrylate" means at least one of acrylate and methacrylate, "(meth) acrylic" means acrylic and methacryl, and "(meth)allyl" means at least one of allyl and methallyl.
In the present disclosure, the average thickness of a layer or film other than the wavelength conversion layer is a value obtained by measuring the thickness of the target layer or film at five points and giving the arithmetic mean value.
In the present disclosure, the average thickness of the wavelength conversion layer is obtained by dividing the wavelength conversion layer into 9 regions of 3 × 3 obtained by dividing the wavelength conversion layer into 3 equal parts vertically and horizontally, and measuring the thickness at the center of each divided region. The value obtained as the arithmetic mean of the thickness of each region obtained.
In the present disclosure, the difference between the maximum thickness and the minimum thickness of the wavelength conversion layer is obtained by dividing the wavelength conversion layer into 9 regions of 3 × 3 obtained by equally dividing the wavelength conversion layer into 3 equal parts vertically and horizontally. The thickness is measured, and the difference between the maximum thickness and the minimum thickness obtained is referred to.
In the present disclosure, the "full width at half maximum" of the wavelength spectrum means "full width at half maximum".

<Wavelength conversion member>
The wavelength conversion member of the present disclosure has a wavelength conversion layer containing a phosphor, the average thickness of the wavelength conversion layer is 80 μm or less, and the maximum thickness of the wavelength conversion layer with respect to the average thickness of the wavelength conversion layer The ratio of the difference from the minimum thickness is 0.01 to 0.1.

In wavelength conversion members having a thickness of several hundred μm, which have hitherto been mainstream, in-plane variations in optical characteristics caused by variations in the thickness of the wavelength conversion layer have rarely been considered a problem. However, in-plane variations in optical characteristics such as a white point and brightness have become apparent as compared with the past due to the miniaturization and thinning of the wavelength conversion member. In particular, when the average thickness of the wavelength conversion layer is 80 μm or less, the influence of the thickness variation due to the thinning of the wavelength conversion member increases, and the influence of the thickness variation on the in-plane variation of the optical properties cannot be ignored. I know I can get it. Furthermore, it is considered that the allowable range of variations in the thickness of the wavelength conversion layer is also affected by the average thickness of the wavelength conversion layer.
As a result of intensive studies, the present inventors have found that the ratio of the difference B between the maximum value and the minimum value of the thickness of the wavelength conversion layer to the average thickness A of the wavelength conversion layer (difference B/average thickness A) is the optical characteristic. The present invention was completed by optimizing the ratio (difference B/average thickness A) after discovering that it is important for eliminating in-plane variations.

In the present disclosure, the ratio (difference B/average thickness A) is 0.01 to 0.1. The ratio (difference B/average thickness A) is preferably 0.09 or less, more preferably 0.08 or less, from the viewpoint of further improving display uniformity on the image display device. From the viewpoint of improving the productivity of the wavelength conversion member, the ratio (difference B/average thickness A) is preferably 0.015 or more, more preferably 0.020 or more.
The average thickness of the wavelength conversion layer is 80 μm or less, preferably 75 μm or less, more preferably 70 μm or less. The average thickness of the wavelength conversion layer may be 20 μm or more.

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 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 is determined by a method conforming to JIS K 7136:2000.

(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 Further, it may be 1.0% by mass or less, 0.8% by mass or less, or 0.5% 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

(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 alumina particles are more preferred.

The refractive index of the light scattering particles that may be contained in the wavelength conversion layer may be 2.6 or less, 2.3 or less, 2.1 or less, or 2.0. It may be less than or equal to 1.9. The smaller the refractive index of the light scattering particles, the greater the proportion of forward scattered light in the obtained scattered light.
The lower limit of the refractive index of the light scattering particles is not particularly limited. From the viewpoint of obtaining a sufficient light scattering effect, the refractive index may be 1.4 or more, or 1.5 or more.

Specific examples of light scattering particles having a refractive index of 2.3 or less include particles of alumina, zirconia, silica, zinc oxide, acrylic resins, silicone resins, barium sulfate, calcium carbonate, and the like.

The light scattering particles contained in the wavelength conversion layer may be of one type or two or more types. Further, even if the wavelength conversion layer contains only light scattering particles with a refractive index of 2.3 or less, it also contains light scattering particles with a refractive index of 2.3 or less and light scattering particles with a refractive index of more than 2.3. It's okay. Specific examples of light scattering particles having a refractive index of greater than 2.3 include titanium oxide.

From the viewpoint of obtaining a sufficient light scattering effect, the content of the light scattering particles may be 0.5% by mass or more, or 1.0% by mass or more, relative to the entire wavelength conversion layer. , 2.0% by mass or more. From the viewpoint of ensuring sufficient brightness, the content of the light scattering particles may be 20% by mass or less, 15% by mass or less, or 10% 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 0.5% by mass to 20% by mass, and is 1.0% by mass to 15% by mass. is more preferable, and 2.0% by mass to 10% by mass is even more preferable.
When the wavelength conversion layer contains light scattering particles with a refractive index of greater than 2.3, the content of the light scattering particles with a refractive index of greater than 2.3 is 5% of the wavelength conversion layer from the viewpoint of ensuring sufficient brightness. It is preferably less than 1% by mass, more preferably less than 1% by mass, and even more preferably less than 0.5% by mass.

When the wavelength conversion layer contains light scattering particles with a refractive index greater than 2.3, the above-mentioned "light scattering particle content (% by mass)" is the light scattering particles with a refractive index of 2.3 or less and a refractive index of It is the total content with light scattering particles greater than 2.3.

From the viewpoint of ease of forming the wavelength conversion layer, the average particle size of the light scattering particles may be 3.5 μm or less, 2.5 μm or less, or 2.0 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, 0.3 μm or more, or 0.5 μm or more. It may be 1.0 μm or more.

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.

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 80% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass.

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. , more preferably 10% by mass to 60% by mass, and even more preferably 15% by mass to 50% by mass.
When the content of the thiol compound is 5% by mass or more, the adhesion of the cured product 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 of the cured product And the wet heat resistance tends 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 75% 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.

(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 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 surface of the covering material facing the wavelength conversion layer.

The oxygen permeability of the covering material is, for example, preferably 1.0 mL/(m ² · 24 h · atm) or less, more preferably 0.8 mL / (m ² · 24 h · atm) or less, and 0 It is more preferably 0.6 mL/(m ² ·24 h·atm) or less. 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 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 dressing may have a light scattering layer to scatter light. When the covering material has a light scattering layer, it is preferable to have the light scattering layer on the surface of the covering material opposite to the surface facing the wavelength conversion layer.
The light scattering layer may contain a vinyl alcohol resin and filler particles. The filler particles may be inorganic particles such as silica and alumina, or resin particles such as acrylic resin and styrene resin.
Also, the wavelength conversion layer and the coating material arranged on one side of the wavelength conversion layer on the side not facing the wavelength conversion layer, or on both sides of the wavelength conversion layer At least one of the surfaces on the side not facing may be roughened. When the wavelength conversion member has a coating material, if the surface of the coating material is roughened, the handling of the image conversion member is excellent, and interference fringes due to close contact between adjacent members and the wavelength conversion member can be suppressed. There is a tendency.
The surface of the covering material may have, for example, an arithmetic surface roughness Ra of 0.5 μm or more. Arithmetic surface roughness Ra is measured by a method conforming to JIS B 0601:2013.

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, the reflectance is higher than light of wavelengths other than light emitted by the phosphor). means a layer having properties.
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 in all directions different from the direction of incidence on the wavelength conversion layer, a portion 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. There may be. 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 layer, 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 150 μm.

(Configuration example of wavelength conversion member)
An example of a schematic configuration of the wavelength conversion member is shown in FIG. However, the wavelength conversion member of the present disclosure is not limited to the configuration of FIG. 1 . Moreover, the sizes of the wavelength conversion layer and the coating material in FIG. 1 are conceptual, and the relative relationship of the sizes is not limited to this.

The wavelength conversion member 10 shown in FIG. 1 has a wavelength conversion layer 11 and coating materials 12A and 12B provided on both sides of the wavelength conversion layer 11 . The types and average thicknesses of the covering material 12A and the covering material 12B may be the same or different.

The wavelength conversion member having the configuration shown in FIG. 1 can be manufactured, for example, by the following known manufacturing method.

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, the wavelength conversion member having the structure shown in FIG. 1 can be obtained by cutting it into a specified size.
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.

Moreover, when irradiating the active energy ray, the irradiation intensity of the active energy ray may be changed stepwise to cure the coating film and form a cured product layer. By changing the irradiation intensity of the active energy ray stepwise, the ratio of the wavelength conversion layer (difference B/average thickness A) tends to be within the range of 0.01 to 0.1. When the irradiation intensity of the active energy ray is not changed stepwise, compared to the case where the irradiation intensity is changed stepwise, by reducing the amount of light scattering particles contained as necessary in the wavelength conversion layer, the wavelength The conversion layer ratio (difference B/average thickness A) tends to be in the range of 0.01 to 0.1.

<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 wavelength conversion member 10 arranged to face the light source 21, and a retroreflection light arranged to face the light source 21 via the wavelength conversion member 10. and a magnetic member 23 . 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 wavelength conversion resin composition)
A mixture containing the following components was blended with light scattering particles in an amount such that the content in the wavelength conversion layer was the value (% by mass) described in Table 2 or Table 3, and the wavelength conversion resin of each example and comparative example was added. A composition was prepared.
As a polyfunctional (meth) acrylate compound, tricyclodecane dimethanol diacrylate (Shin-Nakamura Chemical Co., Ltd.) 73 parts by mass As a polyfunctional thiol compound, pentaerythritol tetrakis (3-mercaptopropionate) (SC Organic Chemical Co., Ltd.) , PEMP) 20.5 parts by mass As a photopolymerization initiator, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (BASF Corporation, IRGACURE TPO) 0.5 parts by mass As a green-emitting phosphor, quantum dot phosphor dispersion Liquid (Nanosys, InP/ZnS (core/shell) dispersion, Gen3.0 QD Concentrate) 5.0 parts by mass Quantum dot phosphor dispersion as a red-emitting phosphor (Nanosys, InP/ZnS (core/shell) Dispersion, Gen3.0 QD Concentrate) 1.5 parts by mass

As the light scattering particles, the following were used.
Alumina particles (Al ₂ O ₃ ): refractive index 1.77, average particle size: 1.7 μm
Zirconia particles (ZrO ₂ ): refractive index 2.13, average particle size: 0.47 μm
Titanium oxide particles (TiO ₂ ): refractive index 2.50, average particle size: 0.36 μm

Isobornyl acrylate was used as the dispersion medium for the InP/ZnS (core/shell) dispersion. The InP/ZnS (core/shell) dispersion contains 90% by mass or more of isobornyl acrylate.

(Manufacture of wavelength conversion member)
Each wavelength conversion resin composition obtained above was applied to the surface of the following coating material 1 on which the barrier component was deposited to form a coating film. On this coating film, the same coating material as the coating material on which the coating film was formed was laminated so that the surface on which the barrier component was deposited was in contact with the coating film. In order to cure the wavelength conversion resin composition, it was irradiated with ultraviolet rays using an ultraviolet irradiation device (I-Graphics Co., Ltd.). As a result, a wavelength conversion member containing a cured product of the wavelength conversion resin composition and having coating materials disposed on both sides of the wavelength conversion layer was produced, cut into sizes shown in Table 1, and each example and comparative example. was obtained. The size of the wavelength conversion member is as shown in Table 2 or Table 3.
Coating material 1: A barrier film having an average thickness of 70 μm, in which a barrier component is vapor-deposited on one side of a PET film and a light scattering layer is provided on the other side. The irradiation intensity change in Table 2 or Table 3 was indicated as "Yes" when the irradiation intensity was changed to , and the irradiation intensity change in Table 2 or Table 3 was indicated as "No" when the irradiation intensity was not changed. The total irradiation dose was 1000 mJ/cm ² regardless of whether there was a change in irradiation intensity or not.

(Measurement of average thickness of wavelength conversion layer and difference between maximum thickness and minimum thickness)
The wavelength conversion layer in each wavelength conversion member is divided into 9 regions of 3×3 obtained by dividing the wavelength conversion layer into 3 equal parts vertically and horizontally, and the thickness of the center of each divided region is measured using a digimatic indicator ID-C112X ( (manufactured by Mitutoyo Co., Ltd.), the arithmetic mean of the thickness of each region obtained was calculated, and the average thickness A was obtained.
Also, the difference B between the maximum thickness and the minimum thickness of the wavelength conversion layer was obtained from the maximum and minimum thicknesses of the center of each divided region obtained as described above.
A ratio (difference B/average thickness A) was obtained from the obtained average thickness A and the difference B between the maximum thickness and the minimum thickness. The obtained results are shown in Table 2 or Table 3.

(white point measurement)
The wavelength conversion layer in each wavelength conversion member is divided into 3×3=9 regions obtained by equally dividing the wavelength conversion layer into 3 equal parts vertically and horizontally. was used to obtain the x and y values of the xy chromaticity diagram at the white point. A difference Δx between the maximum and minimum x values in each divided region and a difference Δy between the maximum and minimum y values in each divided region were calculated.
As a luminance meter, a camera unit that recognizes optical characteristics is installed at the top, and a BEF (brightness enhancement film) plate, a diffusion plate, and an LED light source are provided under the lens, and measurements are taken between the BEF plate and the diffusion plate. A sample set was used that was configured to measure the x and y values.

As is clear from the evaluation results described in Table 2 or Table 3, the wavelengths of Examples 1 to 19 in which the ratio of the wavelength conversion layer (difference B/average thickness A) is in the range of 0.01 to 0.1 The white point Δx and Δy values for the conversion member are smaller than the white point Δx and Δy values for the wavelength conversion member of Comparative Example 1. FIG. Therefore, it can be seen that the wavelength conversion members of Examples 1 to 19 have smaller in-plane variations in optical characteristics than the wavelength conversion member of Comparative Example 1. FIG.

10 wavelength conversion member 11 wavelength conversion layer 12A, 12B coating material 20 backlight unit 21 light source 23 retroreflective member 30 liquid crystal display device 31 liquid crystal cell unit 32 liquid crystal cell 33A, 33B polarizing plate

Claims (12)

having a wavelength conversion layer containing a phosphor,
The average thickness of the wavelength conversion layer is 80 μm or less,
A wavelength conversion member, wherein the ratio of the difference between the maximum thickness and the minimum thickness of the wavelength conversion layer to the average thickness of the wavelength conversion layer is 0.01 to 0.1. The wavelength conversion member according to claim 1, 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 2 including at least one of. 4. Any one of claims 1 to 3, wherein the wavelength conversion layer contains light scattering particles, and the content of the light scattering particles is 0.5 mass % to 20 mass % with respect to the entire wavelength conversion layer. The wavelength conversion member according to item 1. 5. The wavelength conversion member according to claim 4, 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. 6. The wavelength conversion member according to any one of claims 1 to 5, further comprising a covering material that covers at least part of the wavelength conversion layer. 7. The wavelength conversion member according to claim 6, wherein the coating material has an average thickness of 10 μm to 150 μm. The wavelength conversion member according to claim 6 or 7, wherein the coating material has barrier properties against at least one of oxygen and water. The wavelength conversion member according to any one of claims 6 to 8, wherein the covering material has a light scattering layer. 10. The wavelength conversion member according to any one of claims 1 to 9, further comprising a wavelength selective transmission layer. A backlight unit comprising the wavelength conversion member according to any one of claims 1 to 10 and a light source. An image display device comprising the backlight unit according to claim 11 .

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