Wavelength conversion member, method for manufacturing the wavelength conversion member, light-emitting device, and liquid crystal display device.

Abstract

Provided is a wavelength conversion member that comprises a wavelength conversion layer and a base member, wherein the wavelength conversion layer includes a binder and microparticles, and the microparticles each contain a pyrromethene derivative and a matrix.

Description

Technical Field

[0001] The present invention relates to a wavelength conversion member, a method for manufacturing the wavelength conversion member, a light-emitting device, and a liquid crystal display device.

Background Art

[0002] Flat panel displays such as liquid crystal display devices (hereinafter also referred to as LCDs (Liquid Crystal Displays)) are image display devices with low power consumption and space-saving features, and their applications have been expanding year by year. A liquid crystal display device is usually composed of at least a light-emitting device and a liquid crystal cell.

[0003] Regarding flat panel displays, in recent years, improvement of color reproducibility by a wavelength conversion method has been actively studied. To improve color reproducibility, it is effective to narrow the half-value width of each emission spectrum of blue, green, and red in the backlight unit and increase the color purity of each of blue, green, and red. The white light obtained thereby can be made highly bright. As means for solving this, quantum dots using inorganic semiconductor fine particles (for example, see Patent Document 1), and various light-emitting materials (for example, see Patent Documents 2 to 5) have been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

先行技術文献

特許文献

特許文献1

特許文献2

特許文献3

特許文献4

特許文献5

発明の概要

発明が解決しようとする課題

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0005] The light-emitting materials described in Patent Document 1 and Patent Document 2 have narrow full widths at half maximum for green and red emission spectra, and although color reproduction is improved, their durability against heat, moisture in the air, and / or oxygen was insufficient.

[0006] Organic light-emitting materials may degrade due to radicals generated by singlet oxygen and / or light irradiation. In response to this, Patent Document 3 discloses that durability can be improved by using a specific pyromethene derivative for the structure of the organic light-emitting material and reducing the free volume of the resin that acts as a binder for the light-emitting material. On the other hand, Patent Document 4 discloses that durability can be improved by micronizing quantum dot materials and dispersing them in a resin with high oxygen barrier properties.

[0007] Regarding pyrometene derivative light-emitting materials, Patent Document 5 discloses that higher color purity can be obtained by laminating red and green light-emitting materials in separate layers rather than incorporating them in the same layer. However, when forming a laminate, if a composition containing two types of organic light-emitting materials is continuously coated onto a substrate, the organic light-emitting materials mix near the interface, making it conventionally difficult to maintain high color purity. On the other hand, the process of independently fabricating two layers containing different organic light-emitting materials and then laminating them together is complicated.

[0008] One aspect of the present invention aims to provide a wavelength conversion member that can achieve both high color purity and durability, and that can be easily manufactured, as well as a light-emitting device and a liquid crystal display device that use this wavelength conversion member. [Means for solving the problem]

[0009] One aspect of the present invention is, It has a wavelength conversion layer and a substrate, The above wavelength conversion layer contains a binder and microparticles, and The above microparticles contain a pyromethene derivative and a matrix, and are used as a wavelength conversion member. Regarding.

[0010] In one form, the oxygen permeability coefficient of the above binder is 0.01 (cc·mm) / (m 2 It can be less than or equal to (day·atm).

[0011] In one embodiment, the wavelength conversion layer may contain 0.01 to 5% by mass of an emulsifier.

[0012] In one embodiment, the average particle size of the above-mentioned microparticles can be between 1 μm and 15 μm.

[0013] In one form, The above wavelength conversion layer, Microparticles 34G containing a pyrometene derivative that exhibits emission observed in the region of 500 nm to 580 nm peak wavelength when excitation light is used, Microparticle 34R containing a pyrometene derivative that exhibits emission observed in the region of 580 nm to 750 nm with a peak wavelength when excitation light is used, It can contain.

[0014] In one embodiment, the wavelength conversion member may include a laminate 26Y of a wavelength conversion layer 26G containing the microparticles 34G and a wavelength conversion layer 26R containing the microparticles 34R.

[0015] In one embodiment, the wavelength conversion member may have a layer as the wavelength conversion layer that includes the microparticles 34G and 34R in the same layer.

[0016] One aspect of the present invention is, A method for manufacturing a wavelength conversion member, comprising applying a composition containing the above-mentioned microparticles 34G onto a substrate to form a wavelength conversion layer 26G, and further applying a composition containing the above-mentioned microparticles 34R onto the wavelength conversion layer 26G to form a wavelength conversion layer 26R, thereby forming a laminate 26Y. Regarding.

[0017] One aspect of the present invention relates to a light-emitting device including the wavelength conversion member and a light source.

[0018] In one embodiment, the light source can be selected from the group consisting of blue light-emitting diodes and ultraviolet light-emitting diodes.

[0019] One aspect of the present invention relates to a liquid crystal display device having the above-mentioned light-emitting device and a liquid crystal cell. [Effects of the Invention]

[0020] According to one aspect of the present invention, a wavelength conversion member can be provided that achieves both high color purity and durability, and can be easily manufactured. Furthermore, according to one aspect of the present invention, a light-emitting device including this wavelength conversion member and a liquid crystal display device including this light-emitting device can be provided. [Brief explanation of the drawing]

[0021] [Figure 1] Figure 1 conceptually shows an example of a backlight unit using a wavelength conversion member according to one aspect of the present invention. [Figure 2] Figure 2 conceptually shows the configuration of the wavelength conversion member 16. [Modes for carrying out the invention]

[0022] The following description may be based on representative embodiments of the present invention. However, the present invention is not limited to such embodiments. In the present invention and this specification, numerical ranges represented by "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits.

[0023] In the present invention and this specification, "microparticles" means particles with a particle diameter in the range of 50 nm to 500 μm. For microparticles contained in the wavelength conversion layer, the average particle diameter is preferably 0.5 μm to 20 μm, and more preferably 1 μm to 15 μm. The particle diameter and average particle diameter will be described later. The shape of the microparticles is not particularly limited and may be spherical, elliptical, irregular, or any other shape.

[0024] Furthermore, in the present invention and this specification, "(meth)acrylate" is used to refer to either acrylate or methacrylate, or both. The same applies to "(meth)acryloyl," etc.

[0025] [Wavelength conversion component] Figure 1 conceptually shows an example of a backlight unit using a wavelength conversion member according to one aspect of the present invention. The backlight unit 10 is a direct-type planar backlight unit (planar illumination device) used as a backlight for a liquid crystal display device, and comprises a housing 14, a wavelength conversion member 16, and a light source 18. The wavelength conversion member 16 is a wavelength conversion member according to one aspect of the present invention. In the following explanation, "liquid crystal display device" will also be referred to as "LCD." Note that "LCD" is an abbreviation for "Liquid Crystal Display." Furthermore, Figure 1 is merely a schematic diagram, and the backlight unit 10 may have various known components other than those shown, such as one or more LED (Light Emitting Diode) substrates, wiring, and heat dissipation mechanisms, which are provided in known backlight units such as LCD backlights.

[0026] The housing 14 is, for example, a rectangular housing with its largest surface open, and the wavelength conversion member 16 is arranged so as to close the open surface. The housing 14 is a known housing used for LCD backlight units and the like. Furthermore, in a preferred configuration, the housing 14 has a light-reflecting surface selected from a mirror surface, a metallic reflective surface, and a diffuse reflective surface, at least on its bottom surface which serves as the mounting surface for the light source 18. Preferably, the entire inner surface of the housing 14 is a light-reflecting surface.

[0027] The wavelength conversion member 16 is a wavelength conversion member that receives light irradiated by the light source 18, converts its wavelength, and emits it. As described above, this wavelength conversion member 16 is a wavelength conversion member according to one aspect of the present invention. The wavelength conversion member 16 has at least a wavelength conversion layer and a substrate. The substrate can support the wavelength conversion layer.

[0028] Figure 2 conceptually shows the configuration of the wavelength conversion member 16. The wavelength conversion member 16 has a wavelength conversion layer 26 and a base material 28 that sandwiches and supports the wavelength conversion layer 26. Furthermore, the wavelength conversion layer 26 has a binder 32 and microparticles 34 dispersed in the binder 32. The microparticles 34 include a pyrometene derivative 38 and a matrix 36, with the pyrometene derivative 38 dispersed in the matrix 36.

[0029] <Wavelength conversion layer> The wavelength conversion layer 26 has the function of converting the wavelength of incident light and emitting it. For example, when blue light irradiated from the light source 18 is incident on the wavelength conversion layer 26, the wavelength conversion layer 26 converts at least a portion of this blue light to red or green light and emits it due to the effect of the pyrometene derivative 38 contained inside. Here, blue light is light with an emission center wavelength in the wavelength band of 400 to 500 nm. Green light is light with an emission center wavelength in the wavelength band between 500 nm and 580 nm. Red light is light with an emission center wavelength in the wavelength band between 580 nm and 750 nm. For example, when blue light is incident as excitation light, white light can be realized through the green light emitted by the pyrometene derivative (G), the red light emitted by the pyrometene derivative (R), and the blue light transmitted through the wavelength conversion layer.

[0030] <Microparticles, binder> In the microparticles 34, the pyrometene derivative may be uniformly dispersed or unevenly dispersed. It is preferable that the pyrometene derivative is uniformly dispersed in the microparticles 34. Furthermore, only one type of pyrometene derivative may be used, or two or more types may be used in combination. When two or more pyrometene derivatives are used in combination, two or more pyrometene derivatives with different wavelengths of emitted light may be used.

[0031] The wavelength conversion layer 26 is formed by dispersing and immobilizing microparticles 34, which are made by dispersing pyrometene derivatives in a matrix 36, in a binder 32. By individually encapsulating two or more different pyrometene derivatives within the microparticles, the mixing of pyrometene derivatives can be reduced even when sequential coating of compositions containing pyrometene derivatives is performed.

[0032] In one embodiment, the wavelength conversion member 16 may include two or more different pyrometene derivatives with different luminescence properties. In one specific embodiment, the wavelength conversion member 16 may include two different pyrometene derivatives with different luminescence properties, and these two pyrometene derivatives may be included in the same wavelength conversion layer. In another specific embodiment, the wavelength conversion member 16 may include two different pyrometene derivatives with different luminescence properties, and these two pyrometene derivatives may be included in different wavelength conversion layers.

[0033] The two pyrometene derivatives with different luminescence characteristics described above can be a pyrometene derivative that exhibits luminescence observed in the region of peak wavelength between 500 nm and 580 nm when excitation light is used, and a pyrometene derivative that exhibits luminescence observed in the region of peak wavelength between 580 nm and 750 nm when excitation light is used.

[0034] In one example of the specific configuration described above, the wavelength conversion member 16 may include, for example, microparticles 34G containing a pyrometene derivative that exhibits emission observed in the region of 500 nm to 580 nm when excitation light is used, and microparticles 34R containing a pyrometene derivative that exhibits emission observed in the region of 580 nm to 750 nm when excitation light is used, all in the same wavelength conversion layer.

[0035] In another example of the specific form described above, the wavelength conversion member 16 may include, for example, a laminate 26Y of a wavelength conversion layer 26G containing the microparticles 34G and a wavelength conversion layer 26R containing the microparticles 34R.

[0036] The formation of the laminate 26Y is preferably carried out by applying a composition containing microparticles 34G onto a substrate to form the wavelength conversion layer 26G, and then applying a composition containing microparticles 34R on the wavelength conversion layer 26G to form the wavelength conversion layer 26R. By applying the coating layers sequentially in this manner, it is not necessary to individually film the wavelength conversion layers 26G and 26R and then laminate them together, thus simplifying the process.

[0037] There are no particular limitations on the thickness of the wavelength conversion layer 26; it can be set appropriately depending on the thickness of the wavelength conversion member 16, the pyrometene derivative 38 used, the binder 32 used, etc. In one embodiment, the film thickness of the wavelength conversion layer 26 is preferably in the range of 10 to 1000 μm, and more preferably in the range of 15 to 100 μm. A film thickness of 10 μm or more of the wavelength conversion layer 26 is preferable because it provides a wavelength conversion layer 26 that emits light with sufficient brightness, and improves the color distribution and brightness distribution caused by the film thickness distribution of the wavelength conversion layer 26.

[0038] In the above wavelength conversion layer, the oxygen permeability coefficient of the binder 32 in which the microparticles 34 are dispersed is 0.01 (cc·mm) / (m 2It is preferable that the temperature is less than or equal to (day·atm). In order to prevent the phosphor from degrading due to oxygen, it is preferable to use a material with high gas barrier properties as the matrix for forming the microparticles containing the phosphor. Generally, phosphors with high luminescence efficiency are hydrophobic. Therefore, in order to hold a sufficient amount of phosphor in the matrix in a properly dispersed state without aggregation in the microparticles, it is preferable to use a hydrophobic material as the matrix. However, because hydrophobic materials have high compatibility with oxygen, the higher the hydrophobicity, the higher the oxygen permeability coefficient, i.e., the lower the gas barrier properties. Conversely, the higher the hydrophilicity, the lower the oxygen permeability coefficient of the material, i.e., the higher the gas barrier properties. Thus, for materials that form the matrix, there is a trade-off relationship between the dispersibility of the phosphor and the gas barrier properties. On the other hand, when using microparticles formed with a hydrophobic matrix, in order to increase the amount of microparticles contained in the wavelength conversion layer and to properly disperse the microparticles containing the phosphor in the binder, it is preferable to use a hydrophilic material as the binder. As mentioned above, the higher the hydrophilicity of the material, the lower the oxygen permeability coefficient, i.e., the higher the gas barrier properties. However, if the microparticles are made of a hydrophobic material, i.e., a material with low gas barrier properties, then if the amount of microparticles is too large, the gas barrier properties of the wavelength conversion layer will decrease, and it will not be possible to prevent the phosphor from degrading due to oxygen. The oxygen permeability coefficient of binder 32 is 0.01 (cc·mm) / (m 2 It is preferable that the oxygen permeability coefficient of the binder 32 is less than or equal to (day·atm) from the viewpoint of preventing degradation of the pyromethene derivative 38 by oxygen. 2 It is more preferable that the oxygen permeability coefficient of the binder 32 is less than or equal to (day·atm). Furthermore, a lower oxygen permeability coefficient of the binder 32 is preferable. Therefore, there is no particular limit to the lower limit of the oxygen permeability coefficient of the binder 32.

[0039] The SI unit for oxygen permeability coefficient is [fm·mm / (s·Pa)]. 'fm' stands for 'femtometer', and '1 fm = 1 × 10⁻¹⁰ -15It is 'm'. The SI units are [fm·mm / (s·Pa)] and [cc·mm / (m 2 (·day·atm) means that 1 fm·mm / (s·Pa) = 8.752cc·mm / (m 2 It can be converted using the formula 'day ATM'. Furthermore, the oxygen permeability coefficient and oxygen permeability can be measured, for example, by the methods shown in JIS K 7126 (isobaric method) and ASTM D3985. These measurements can be taken using an oxygen permeability analyzer from MOCON or an APIMS (atmospheric pressure ionization mass spectrometry) analyzer (for example, manufactured by API Japan Co., Ltd.) under conditions of 25°C and 60% relative humidity.

[0040] There are no particular limitations on the material used to form the binder 32, but preferably it has an oxygen permeability coefficient of 0.01 (cc·mm) / (m 2 Any known material can be used as long as it is below (day·atm) and can hold and fix the microparticles 34, preferably any resin.

[0041] Specifically, examples include polyvinyl alcohol (PVA), modified PVA having substituents such as vinyl groups and (meth)acryloyl groups, ethylene-vinyl alcohol copolymer (EVOH), vinyl alcohol-butenediol copolymer (BVOH), polyvinylidene chloride, and aromatic polyamides (aramids). PVA and modified PVA are preferred examples because they have a low oxygen permeability coefficient and excellent liquid stability over time.

[0042] Generally, PVA is obtained by using polyvinyl acetate, which is obtained by polymerizing vinyl acetate, as a raw material, and saponifying this polyvinyl acetate to replace acetyl groups with hydroxyl groups. Due to this synthesis process, PVA has acetyl groups and hydroxyl groups, and their ratio is expressed as the degree of saponification. In this invention and specification, the degree of saponification is the same as the definition of degree of saponification known in the industry, and refers to the ratio (mol%) of moles of vinyl alcohol units to the total number of moles of structural units (typically vinyl ester units) and vinyl alcohol units that can be converted to vinyl alcohol units by saponification. In particular, when polyvinyl acetate is used as a raw material, it means the value obtained by dividing the number of hydroxyl groups derived from the vinyl alcohol skeleton contained in PVA by the sum of the number of acetyl groups derived from the vinyl acetate skeleton and the number of hydroxyl groups derived from the vinyl alcohol skeleton.

[0043] From the viewpoint of oxygen permeability, the degree of saponification of PVA and modified PVA is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more. Furthermore, from the viewpoint of not impairing the dispersibility of microparticles, the upper limit of the degree of saponification is preferably 99 mol% or less.

[0044] Modification groups in modified PVA can be introduced by copolymerization, chain transfer, or block polymerization. Examples of modification groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups with 10 to 100 carbon atoms, fluorine-substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azilinidyl groups, etc.), and alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy). Specific examples of these modified PVAs include those described in paragraph 0074 of Japanese Patent Publication No. 2000-56310, paragraphs 0022-0145 of Japanese Patent Publication No. 2000-155216, and paragraphs 0018-0022 of Japanese Patent Publication No. 2002-62426.

[0045] Furthermore, the weight-average molecular weight (Mw) of the binder resin can preferably be 5,000 or more, more preferably 15,000 or more, even more preferably 20,000 or more, preferably 500,000 or less, more preferably 100,000 or less, and even more preferably 50,000 or less. If the weight-average molecular weight is within the above range, good compatibility with microparticles and a wavelength conversion member with higher durability can be obtained.

[0046] The weight-average molecular weight in this invention and specification is a value measured by gel permeation chromatography (GPC). Specifically, the sample is filtered through a 0.45 μm pore size membrane filter, and then the value is determined by converting it to polystyrene equivalent using GPC (HLC-82A, manufactured by Tosoh Corporation) (eluent: toluene, elution rate: 1.0 ml / min, column: TSKgelG2000HXL, manufactured by Tosoh Corporation).

[0047] In the binder 32, only one type of resin may be used, or multiple types may be used in combination. Furthermore, commercially available products may be used as the binder 32.

[0048] In the above-described wavelength conversion member, the content of microparticles 34 in the wavelength conversion layer 26 is preferably in the range of 3 to 30 volume%. A content of 3 volume% or more of microparticles 34 in the wavelength conversion layer 26 is preferable from the viewpoint of obtaining sufficient brightness emission and from the viewpoint of thinning the wavelength conversion layer 26, i.e., the wavelength conversion member 16. A content of 30 volume% or less of microparticles 34 in the wavelength conversion layer 26 is preferable from the viewpoint of further preventing degradation of the pyromethene derivative 38 by oxygen and from the viewpoint of properly dispersing the microparticles 34 within the wavelength conversion layer 26. A content of 5 to 25 volume% of microparticles 34 in the wavelength conversion layer 26 is more preferable. The content of microparticles 34 in the wavelength conversion layer 26 can be measured by cutting the wavelength conversion layer 26 with a microtome or the like to form a cross-section, and analyzing the image obtained by observing this cross-section with an optical microscope.

[0049] The binder 32 of the wavelength conversion layer 26 may further contain an emulsifier. Preferably, the wavelength conversion layer 26 may contain an emulsifier in an amount of 0.01 to 5% by mass, more preferably 0.05 to 3% by mass. The inclusion of an emulsifier in the binder 32 is preferable because, by including 0.01% by mass or more of the emulsifier in the wavelength conversion layer 26, the dispersion state of the microparticles 34 in the wavelength conversion layer 26 is improved, resulting in a wavelength conversion member 16 with excellent optical properties that have less chromatic and luminance unevenness in the emission, and the particle size distribution of the microparticles 34 can be made sharper. When the binder 32 contains an emulsifier, it is preferable to limit the emulsifier content in the wavelength conversion layer 26 to 5% by mass or less, as this prevents a decrease in the gas barrier properties of the wavelength conversion layer 26.

[0050] There are no particular limitations on the emulsifier added to the wavelength conversion layer 26, and various known emulsifiers can be used. Preferably, an emulsifier with an HLB value (Hydrophile-Lipophile Balance value) of 8 to 19 or 8 to 18 can be used. In one embodiment, more preferably, an emulsifier with an HLB value of 10 to 16 can be used as the emulsifier added to the wavelength conversion layer 26. Examples of methods for calculating the HLB value include the Griffin method and the Davis method. In the present invention and this specification, the HLB value calculated by the Griffin method is used. In the Griffin method, the HLB value is determined based on the formula weight and molecular weight of the hydrophilic group using the following formula. Therefore, the HLB value in this case is in the range of 0 to 20. HLB value = 20 × (sum of formula weights of hydrophilic groups / molecular weight)

[0051] In one embodiment, the HLB value range is preferably 5 to 19, more preferably 7 to 18, and even more preferably 8 to 17. Keeping the HLB value within the above range is preferable from the viewpoint of improving the dispersibility of microparticles in the binder.

[0052] Examples of emulsifiers include cationic surfactants, anionic surfactants, and nonionic surfactants. Anionic and nonionic surfactants are particularly preferred from the viewpoint of not inhibiting the dispersibility of pyromethene derivatives. Specifically, as anionic surfactants, alkyl sulfates are preferred because they have little odor, good biodegradability, and are relatively environmentally friendly. Specific examples of alkyl sulfates include alkyl sulfates such as sodium octyl sulfate (SOS) (8 carbon atoms), sodium decyl sulfate (10 carbon atoms), and sodium dodecyl sulfate (SDS) (12 carbon atoms). Examples of nonionic surfactants include ether-based surfactants such as polyethylene glycol dodecyl ether, polyethylene glycol octadecyl ether, polyethylene glycol oleyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, and polyoxyethylene alkyl ether; ester-based surfactants such as polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate; acetylene alcohol-based surfactants such as 3,5-dimethyl-1-hexyne-3-ol; and acetylene glycol-based surfactants such as 2,4,7,9-tetramethyl-5-decine-4,7-diol and 3,6-dimethyl-4-octin-3,6-diol.

[0053] Furthermore, commercially available nonionic surfactants such as BRIJ 30, BRIJ 35, BRIJ S10, BRIJ O20, and BRIJ 93 (all manufactured by Sigma-Aldrich) can also be suitably used.

[0054] Furthermore, the wavelength conversion layer 26 may contain, as necessary, a silane coupling agent, a crosslinking agent, a light scattering agent, a viscosity modifier, a surface modifier, an inorganic layered compound, etc., in addition to the emulsifier.

[0055] The wavelength conversion layer 26 can be formed by preparing a dispersion liquid that becomes the microparticles 34, introducing this dispersion liquid into an aqueous solution in which a compound that becomes the binder 32 such as PVA is dissolved, and curing the matrix 36 while stirring, thereby preparing a coating liquid in which the microparticles 34 are dispersed and emulsified in the aqueous solution, applying this coating liquid to the base material 28, and drying it.

[0056] In the wavelength conversion member 16, the oxygen transmission coefficient of the matrix 36, which is the formation material of the microparticles 34, is preferably 10 to 1000 (cc·mm) / (m 2 ·day·atm). That the oxygen transmission coefficient of the matrix 36 is 10 (cc·mm) / (m 2 ·day·atm) or more is preferable for properly dispersing and holding a sufficient amount of the pyromethene derivative 38 in the matrix 36, that is, the microparticles 34, without aggregation. On the other hand, when the pyromethene derivative aggregates, it may cause inconveniences such as a decrease in the luminance of the wavelength conversion layer 28. That the oxygen transmission coefficient of the matrix 36 is 1000 (cc·mm) / (m 2 ·day·atm) or less is preferable from the viewpoint of improving the gas barrier property of the wavelength conversion member 16. The oxygen transmission coefficient of the matrix 36 is more preferably in the range of 10 to 500 (cc·mm) / (m 2 ·day·atm).

[0057] As long as the formation material of the matrix 36 of the microparticles 34 preferably has an oxygen transmission coefficient of 10 to 1000 (cc·mm) / (m 2 ·day·atm), various known materials can be used. As the formation material of the matrix 36, various resins are preferably used.

[0058] As an example, matrix 36 can be a matrix 36 obtained by curing (polymerizing, crosslinking) monofunctional (meth)acrylate monomers and / or polyfunctional (meth)acrylate monomers. Examples of monofunctional (meth)acrylate monomers include acrylic acid and methacrylic acid, their derivatives, and more specifically, aliphatic or aromatic monomers having one polymerizable unsaturated (meth)acryloyl group of (meth)acrylic acid in the molecule and an alkyl group with 1 to 30 carbon atoms. Specific examples of such compounds are listed below. However, the present invention is not limited thereto. Aliphatic monofunctional (meth)acrylate monomers include alkyl (meth)acrylates with 1 to 30 carbon atoms in the alkyl group, such as methyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate; alkoxyalkyl (meth)acrylates with 2 to 30 carbon atoms in the alkoxyalkyl group, such as butoxyethyl (meth)acrylate; aminoalkyl (meth)acrylates with a total of 1 to 20 carbon atoms in the (monoalkyl or dialkyl) aminoalkyl group, such as N,N-dimethylaminoethyl (meth)acrylate; (meth)acrylate of diethylene glycol ethyl ether, (meth)acrylate of triethylene glycol butyl ether, (meth)acrylate of tetraethylene glycol monomethyl ether, (meth)acrylate of hexaethylene glycol monomethyl ether, and monomethyl ether of octaethylene glycol. (meth)acrylates of polyalkylene glycol alkyl ethers having 1 to 10 carbon atoms in the alkylene chain and 1 to 10 carbon atoms in the terminal alkyl ether, such as (meth)acrylate, nonaethylene glycol monomethyl ether (meth)acrylate, dipropylene glycol monomethyl ether (meth)acrylate, heptapropylene glycol monomethyl ether (meth)acrylate, and tetraethylene glycol monoethyl ether (meth)acrylate; and (meth)acrylates of hexaethylene glycol phenyl ether. (meth)acrylates of polyalkylene glycol aryl ethers having 1 to 30 carbon atoms in the alkylene chain and 6 to 20 carbon atoms in the terminal aryl ether; (meth)acrylates with an alicyclic structure and a total of 4 to 30 carbon atoms, such as cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, and methylene oxide-added cyclodecatriene (meth)acrylate; fluorinated alkyl (meth)acrylates with a total of 4 to 30 carbon atoms, such as heptadecafluorodecyl (meth)acrylate;Examples include (meth)acrylates having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, hexaethylene glycol mono(meth)acrylate, octapropylene glycol mono(meth)acrylate, and glycerol mono(meth)acrylate; (meth)acrylates having a glycidyl group, such as glycidyl (meth)acrylate; polyethylene glycol mono(meth)acrylates with 1 to 30 carbon atoms in the alkylene chain, such as tetraethylene glycol mono(meth)acrylate, hexaethylene glycol mono(meth)acrylate, and octapropylene glycol mono(meth)acrylate; and (meth)acrylamides such as (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, 2-hydroxyethyl (meth)acrylamide, and acryloylmorpholine. Examples of aromatic monofunctional acrylate monomers include aralkyl (meth)acrylates, such as benzyl (meth)acrylate, in which the aralkyl group has 7 to 20 carbon atoms.

[0059] In particular, aliphatic or aromatic alkyl (meth)acrylates having 4 to 30 carbon atoms in the alkyl group are preferred, and even more preferably n-octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, and methylene oxide-added cyclodecatriene (meth)acrylate are preferred. This is because it improves the dispersibility of pyromethene derivatives 38 such as quantum dots within the microparticles 34. The more the dispersibility of the pyromethene derivatives 38 improves, the more light is emitted perpendicular to the emission surface from the wavelength conversion layer 26, which is effective in improving frontal brightness and frontal contrast.

[0060] Among the bifunctional or polyfunctional (meth)acrylate monomers, preferred examples of bifunctional (meth)acrylate monomers include neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol diacrylate, tripropylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tricyclodecanedimethanol diacrylate, and ethoxylated bisphenol A diacrylate.

[0061] Among the bifunctional or polyfunctional (meth)acrylate monomers, the trifunctional or more (meth)acrylate monomers include epichlorohydrin (ECH)-modified glycerol tri(meth)acrylate, ethylene oxide (EO)-modified glycerol tri(meth)acrylate, propylene oxide (PO)-modified glycerol tri(meth)acrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, EO-modified phosphate triacrylate, trimethylolpropane tri(meth)acrylate, caprolactone-modified trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, and PO-modified trimethylolpropane tri(meth)acrylate. Examples of preferred materials include lylate, tris(acryloxyethyl) isocyanurate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, dipentaerythritol hydroxypenta(meth)acrylate, alkyl-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol poly(meth)acrylate, alkyl-modified dipentaerythritol tri(meth)acrylate, ditrimethylolpropanetetra(meth)acrylate, pentaerythritol ethoxytetra(meth)acrylate, and pentaerythritol tetra(meth)acrylate.

[0062] As polyfunctional monomers, (meth)acrylate monomers having a urethane bond in the molecule can also be used, specifically adducts of tolylene diisocyanate (TDI) and hydroxyethyl acrylate, adducts of isophorone diisocyanate (IPDI) and hydroxyethyl acrylate, adducts of hexamethylene diisocyanate (HDI) and pentaerythritol triacrylate (PETA), compounds obtained by reacting the remaining isocyanate after the adduct of TDI and PETA with dodecyloxyhydroxypropyl acrylate, adducts of nylon 6,6 and TDI, and adducts of pentaerythritol, TDI, and hydroxyethyl acrylate can also be used.

[0063] These (meth)acrylate monomers may be used in combination in multiple quantities. Furthermore, commercially available (meth)acrylate monomers may be used.

[0064] In addition to cured products of (meth)acrylate monomers, the matrix 36 that forms the microparticles 34 can also suitably use cured products of silicone resins such as polydimethylsiloxane and polyorganosilsesquioxane, acrylic resins, epoxy resins, polyimide resins, urethane resins, urea resins, melamine resins, polyamide resins, polyamide-imide resins, polyester resins, polyolefin resins, polycarbonate resins, etc. The matrix may contain two or more of these or a copolymer. For example, a copolymer of methyl methacrylate and an aliphatic polyolefin resin can be used. Among these, acrylic resin is preferred in terms of stability.

[0065] Examples of acrylic resins include polymers of unsaturated carboxylic acids and copolymers of unsaturated carboxylic acids and other ethylenically unsaturated compounds. Among these, copolymers of unsaturated carboxylic acids and ethylenically unsaturated compounds are preferred.

[0066] Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, and vinylacetic acid. Two or more of these unsaturated carboxylic acids may be used.

[0067] Examples of ethylenically unsaturated compounds include unsaturated alkyl carboxylates, aliphatic vinyl compounds, aromatic vinyl compounds, unsaturated aminoalkyl carboxylates, unsaturated glycidyl carboxylates, vinyl carboxylates, vinyl cyanide compounds, aliphatic conjugated dienes, and macromonomers. Examples of unsaturated alkyl carboxylates include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, isopropyl acrylate, isopropyl methacrylate, n-propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, sec-butyl acrylate, sec-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, benzyl acrylate, and benzyl methacrylate. Examples of aliphatic vinyl compounds include ethylene, n-propylene, n-butene, n-pentene, n-hexene, vinylcyclobutane, vinylcyclopentane, and vinylcyclohexane. "n-", "sec-", and "tert-" are abbreviations for "normal-", "secondary-", and "tertiary-", respectively. Examples of aromatic vinyl compounds include styrene, p-methylstyrene, o-methylstyrene, m-methylstyrene, α-methylstyrene, and monomers containing a fluorene skeleton. "o-", "m-", and "p-" are abbreviations for "ortho-", "meta-", and "para-", respectively. Examples of unsaturated carboxylic acid aminoalkyl esters include aminoethyl acrylate. Examples of unsaturated carboxylic acid glycidyl esters include glycidyl acrylate and glycidyl methacrylate. Examples of carboxylic acid vinyl esters include vinyl acetate and vinyl propionate. Examples of vinyl cyanide compounds include acrylonitrile, methacrylonitrile, and α-chloroacrylonitrile. Examples of aliphatic conjugated dienes include 1,3-butadiene and isoprene.Examples of macromonomers include polystyrene, polymethyl acrylate, polymethyl methacrylate, polybutyl acrylate, polybutyl methacrylate, and polysilicone, all of which have acryloyl or methacryloyl groups at their terminal ends.

[0068] Furthermore, it is preferable that the acrylic resin has ethylenically unsaturated groups in its side chains. Examples of ethylenically unsaturated groups include vinyl groups, allyl groups, acrylic groups, and methacrylic groups. Methods for introducing ethylenically unsaturated groups into the side chains of the acrylic resin include adding ethylenically unsaturated compounds having epoxy groups, acrylic acid chloride, methacrylic acid chloride, etc., to carboxyl groups, hydroxyl groups, etc., when the acrylic resin has these groups, or adding compounds having ethylenically unsaturated groups using isocyanates.

[0069] Examples of acrylic resins having ethylenically unsaturated groups in their side chains include "Cychromer" (registered trademark) P(ACA)Z250 (45% by mass solution of dipropylene glycol monomethyl ether, acid value 110 mg KOH / g, weight-average molecular weight 20,000) manufactured by Daicel Ornex Co., Ltd.

[0070] Examples of reactive monomers that can be used as materials for forming the matrix 36 of microparticles 34 include oligomers such as bisphenol A diglycidyl ether (meth)acrylate, poly(meth)acrylate carbamate, modified bisphenol A epoxy (meth)acrylate, 1,6-hexanediol adipic acid (meth)acrylate, propylene oxide phthalate anhydride (meth)acrylate, diethylene glycol trimellitic acid (meth)acrylate, rosin-modified epoxy di(meth)acrylate, alkyd-modified (meth)acrylate, tripropylene glycol di(meth)acrylate, and 1,6-hexanediol adipic acid. Examples include di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetratrimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, triacrylic formal, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, bisphenoxyethanol full orange acrylate, dicyclopentanedienyl diacrylate, and alkyl-modified products thereof, alkyl ether-modified products, and alkyl ester-modified products. The reactive monomer may contain two or more of these.

[0071] The glass transition temperature (Tg) of the matrix is ​​preferably 50°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher, and even more preferably 90°C or higher, from the viewpoint of improving compatibility with the light-emitting material and enhancing durability. Furthermore, from the viewpoint of achieving appropriate film hardness and suppressing cracks during film formation, the Tg is preferably 200°C or lower, more preferably 180°C or lower, even more preferably 170°C or lower, and even more preferably 160°C or lower. Having the Tg of the matrix resin within the above range is preferable from the viewpoint of further improving the durability of the wavelength conversion member.

[0072] The glass transition temperature can be measured using a commercially available measuring instrument (for example, a differential scanning calorimetry system (DSC7000X) manufactured by Hitachi High-Tech Science Corporation, with a heating rate of 10°C / min).

[0073] There is a strong relationship between the SP value, which is the solubility parameter of the matrix, and the emission peak wavelength of the organic light-emitting material. In matrix resins with a high SP value, the excited state of the organic light-emitting material is stabilized by the interaction between the matrix resin and the organic light-emitting material. Therefore, compared to matrix resins with a low SP value, the emission peak wavelength of this organic light-emitting material shifts to longer wavelengths. Thus, by dispersing the organic light-emitting material in a matrix resin with an optimal SP value, it is possible to optimize the emission peak wavelength of the organic light-emitting material. By optimizing the emission peak wavelength of organic light-emitting materials with high color purity, for example, when incorporated into a display light source as described later, the density of the color filter can be reduced, making it possible to increase the brightness of the display.

[0074] For the SP value of the matrix, SP ≤ 12.0 (cal / cm 3 ) 0.5 This is preferable because it suppresses the lengthening of the emission peak wavelength of red light, and as a result, the difference in emission peak wavelengths between green light and red light becomes smaller. From the viewpoint of further enhancing this effect, it is more preferable that SP ≤ 11.0 (cal / cm²) 3 ) 0.5 And more preferably, SP ≤ 10.5 (cal / cm 3 ) 0.5 The lower limit is SP ≥ 7.0 (cal / cm²). 3 ) 0.5 The matrix is ​​suitable for use because it has good dispersibility of organic luminescent materials. From the viewpoint of further enhancing the effect, SP ≥ 8.0 (cal / cm²) is preferable. 3 ) 0.5 And more preferably, SP ≥ 8.5 (cal / cm 3 ) 0.5 And more preferably, SP ≥ 9.0 (cal / cm 3 ) 0.5 That is the case.

[0075] Here, the solubility parameter (SP value) is a value calculated from the types and ratios of monomers constituting the matrix, using Fedors' estimation method, which is commonly used and described in Poly.Eng.Sci., vol.14, No.2, pp.147-154 (1974), etc. The same method can be used to calculate the SP value for mixtures of multiple types of resins. For example, the SP value of polymethyl methacrylate is 9.7 (cal / cm³). 3 ) 0.5 The SP value of polyethylene terephthalate (PET) can be calculated as follows, and the SP value of polyethylene terephthalate (PET) is 10.8 (cal / cm³). 3 ) 0.5 The SP value of the bisphenol A epoxy resin can be calculated as follows, and the SP value of the bisphenol A epoxy resin is 10.9 (cal / cm²). 3 ) 0.5 It can be calculated as follows.

[0076] Furthermore, the weight-average molecular weight (Mw) of the matrix is ​​preferably 5,000 or more, more preferably 15,000 or more, even more preferably 20,000 or more, even more preferably 500,000 or less, even more preferably 100,000 or less, and even more preferably 50,000 or less. If the weight-average molecular weight is within the above range, good compatibility with the light-emitting material and a wavelength conversion member with higher durability can be obtained.

[0077] The method of matrix synthesis is not particularly limited; known methods can be used as appropriate, and commercially available products can also be used.

[0078] Specific examples of commercially available products include "OKP4" and "OKP-A1" from Osaka Gas Chemical Co., Ltd., "Dianal BR-83, BR-85, and BR-87" from Mitsubishi Chemical Corporation, "Byron 200, GK-360, UR-1400, and UR-4800" from Toyobo Co., Ltd., "Oricox KC-700 and KC-7000F" from Kyoeisha Chemical Co., Ltd., "Nichigo Polyester TP-220, TP-294, and LP-033" from Nippon Synthetic Chemical Industry Co., Ltd., "Yupizeta EP-5000, Optimas 7500, and Optimas 6000" from Mitsubishi Gas Chemical Co., Ltd., "Aron PE-1000, A-104, A-106, S-1001, S-1017, and S2060" from Toagosei Chemical Co., Ltd., and "Hi-pearl" from Negami Kogyo Co., Ltd. Examples include M-4006 and M-4620, "Estyrene AS-30", "Estyrene AS-61", and "Estyrene AS-70" manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd., and "SGP-10" manufactured by PS Japan Co., Ltd.

[0079] In addition to the matrix 36 and the pyrometene derivative 38, the microparticles 34 may optionally contain polymerization initiators, viscosity modifiers, thixotropic agents, hinted amine compounds, antioxidants, light scattering agents, polymer dispersants, surfactants, etc. For example, by containing a hinted amine compound in the microparticles 34, it is possible to suppress the discoloration of the microparticles 34 under high-intensity light.

[0080] Known methods can be used to form microparticles. Microparticle formation methods can be broadly classified into "breakdown," which involves crushing the bulk material into fine particles, and "build-up," which generates fine particles by controlling the growth of molecular aggregates through chemical reactions. There are two specific methods for breakdown (i.e., grinding): the "wet method" and the "dry method." The dry method has a larger particle size limit for grinding, and considering productivity, the wet method offers many advantages. Therefore, when generating microparticles by breakdown, wet grinding is considered effective. In wet grinding, a "bead mill" is a device that can efficiently generate fine particles ranging from submicron to tens of nanometers. On the other hand, in build-up processes, particles are formed from atomic or molecular agglomerative materials through nucleation and growth via chemical reactions or physical cooling of the solution. Depending on the initial state of the raw materials, these processes are classified into three types: "gas-phase processes," "liquid-phase processes," and "solid-phase processes." In gas-phase processes, the solution is atomized by pressurized spraying or other means, and solidified microparticles are formed by rapid drying. Specific methods include spray drying and drop-in methods. Among these, spray drying is preferable from the viewpoint of producing small particle sizes and excellent productivity. In liquid-phase processes, microparticles are formed by polymerizing a polymerizable composition dispersed or emulsified in a solution using heat, light, etc., under stirring. Specific methods include emulsion polymerization, dispersion polymerization, and suspension polymerization. From the viewpoint of excellent productivity, it is preferable to form microparticles by spray drying, emulsion polymerization, or suspension polymerization.

[0081] As an example of a specific form of microparticle formation, the following method can be exemplified. A dispersion is prepared by adding a pyromethene derivative to a liquid compound that will serve as a matrix 36, such as the (meth)acrylate monomer mentioned above. This dispersion is then added to an aqueous solution containing a compound that will serve as a binder 32, such as polyvinyl alcohol described later, and while stirring, the compound that will serve as the matrix 36 in the dispersion is cured to form microparticles 34. The microparticles 34 may contain polymerization initiators or the like.

[0082] As an example of a specific form of microparticle formation, the following method can also be exemplified. A dispersion is prepared by adding a pyromethene derivative and a solvent to a matrix compound such as the aforementioned acrylic resin, and this dispersion is sprayed in a mist from a spray nozzle and dried in a constant temperature bath (dryer) connected to the nozzle opening to form microparticles 34. The obtained microparticles may be further dried in another constant temperature bath to remove residual solvent, etc. The microparticles 34 may also contain additives such as light scattering particles and polymerization initiators.

[0083] The particle size of the microparticles 34 is as described above. The average particle size of the microparticles 34 contained in the wavelength conversion layer is preferably 0.5 μm or more and 20 μm or less, and more preferably 1 μm or more and 15 μm or less. It is preferable that the average particle size of the microparticles 34 is 0.5 μm or more (more preferably 1 μm or more) because it allows the microparticles 34 to be dispersed in the binder 32 without aggregation. Having an average particle diameter of 20 μm or less (more preferably 15 μm or less) for the microparticles 34 is preferable in that it allows for thinning of the wavelength conversion layer 26, suppresses the sedimentation of microparticles 34 in the coating solution described later, and extends the pot life of the coating solution. The particle size of microparticles can be determined by taking particle images using an optical microscope, scanning electron microscope (SEM), etc., analyzing the obtained images, and using the following formula. The same method applies to the particle size of light-scattering particles, which will be discussed later. Particle diameter = (length of major axis + length of minor axis) / 2 The average particle size of microparticles can be determined by the following method. The wavelength conversion layer is cut using a microtome to form a cross-section. The formed cross-section is observed with an optical microscope (reflected light) to obtain a cross-sectional image. The arithmetic mean of the particle diameters of 50 randomly selected particles in the obtained cross-sectional image can be used as the average particle diameter of the microparticles contained in the wavelength conversion layer. Alternatively, the average particle diameter of the microparticles contained in the wavelength conversion layer can be determined by analyzing the obtained cross-sectional image with image analysis software (e.g., ImageJ).

[0084] There are no particular limitations on the pyrometene derivative content in the microparticles 34, and it can be set appropriately depending on the type of pyrometene derivative used, the particle size of the microparticles 34, etc. In one embodiment, a range of 0.01 to 20% by mass is preferred, a range of 0.1 to 20% by mass is more preferred, and a range of 0.1 to 10% by mass is even more preferred. Having a pyrometene derivative content of 0.01% by mass or more in the microparticles 34 is preferable because it allows for high-brightness light emission by retaining a sufficient amount of pyrometene derivative 38, sufficient brightness can be obtained without unnecessarily thickening the wavelength conversion layer 26, and the wavelength conversion member 16 can be made thinner. Having a pyrometene derivative content of 20% by mass or less in the microparticles 34 is preferable because it allows the pyrometene derivative to disperse nicely without aggregation within the microparticles 34, enabling high-brightness luminescence with high quantum yield, and suppresses light loss due to self-absorption and re-absorption of the pyrometene derivative.

[0085] Microparticles may be subjected to appropriate surface treatments to further enhance reliability, particle dispersibility, transmittance, etc. One example of a surface treatment is to form a coating layer impermeable to oxygen and / or moisture to improve reliability. However, this is not limited to this method.

[0086] The coating layer described above is preferably made of a material that has low permeability to moisture and / or oxygen and is transparent in the visible light range. Suitable materials include metal oxides and metal nitrides, specifically silicon dioxide (SiO2) and aluminum oxide (Al2O3), but are not limited to these. Any known method can be used to form the coating layer, such as plating, PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), and ALD (Atomic Layer Deposition). Among these, PVD and CVD are preferred from the viewpoint of forming a thin film uniformly on the surface of microparticles, and polygonal barrel sputtering and polygonal barrel plasma CVD are more preferred from the viewpoint of excellent productivity.

[0087] From the viewpoint of improving the dispersibility of microparticles in the binder, it is preferable to appropriately control the solubility parameter (SP value) between the binder resin and the microparticle matrix. Specifically, from the viewpoint of preventing the elution of microparticles in the binder, the difference in SP values ​​between the binder resin and the microparticle matrix (ΔSP value) should be ΔSP value > 1.0 (cal / cm²). 3 ) 0.5 Preferably, the ΔSP value > 2.0 (cal / cm²) 3 ) 0.5 It is more preferable that the ΔSP value > 3.0 (cal / cm²) 33 ) 0.5 It is even more preferable that the SP value < 20.0 (cal / cm³) is used, because if the difference in solubility parameters becomes too large, aggregation of microparticles may occur. 3 ) 0.5 Preferably, the ΔSP value is < 17.0 (cal / cm²). 3 ) 0.5 It is more preferable that the ΔSP value < 16.0 (cal / cm²). 3 ) 0.5 It is even more preferable that the ΔSP value is controlled within the range described above, which tends to prevent the elution and / or secondary aggregation of microparticles and result in good dispersibility.

[0088] <Pyromethene derivatives> The pyromethene derivative is preferably a compound represented by the following general formula (1).

[0089] [ka]

[0090] (In general formula (1), X is CR 7 Or it is N (nitrogen atom). 1 ~R 9 These may be the same or different, and each is independently selected from among a hydrogen atom, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, hydroxyl group, thiol group, alkoxy group, alkylthio group, aryl ether group, arylthioether group, aryl group, heteroaryl group, halogen, cyano group, aldehyde group, carbonyl group, carboxyl group, ester group, carbamoyl group, amino group, nitro group, silyl group, siloxanyl group, boryl group, sulfo group, phosphine oxide group, and condensed rings and aliphatic rings formed with adjacent substituents.

[0091] In general formula (1), X is CR 7 And R 7 However, it is preferable that the group is represented by general formula (2).

[0092] [ka]

[0093] (In general formula (2), r is selected from the group consisting of hydrogen atoms, alkyl groups, cycloalkyl groups, heterocyclic groups, alkenyl groups, cycloalkenyl groups, alkynyl groups, hydroxyl groups, thiol groups, alkoxy groups, alkylthio groups, aryl ether groups, arylthioether groups, aryl groups, heteroaryl groups, halogens, cyano groups, aldehyde groups, carbonyl groups, carboxyl groups, ester groups, carbamoyl groups, amino groups, nitro groups, silyl groups, siloxanyl groups, boryl groups, sulfo groups, and phosphine oxide groups. k is an integer in the range of 1 to 3. If k is 2 or greater, r may be the same or different.)

[0094] In general formula (1), R 1 ~R 6 Preferably, at least one of them is an electron-withdrawing group. Preferred electron-withdrawing groups include a fluorine atom, a fluorine-containing aryl group, a fluorine-containing heteroaryl group, a fluorine-containing alkyl group, a substituted or unsubstituted acyl group, a substituted or unsubstituted ester group, a substituted or unsubstituted amide group, a substituted or unsubstituted sulfonyl group, or a cyano group.

[0095] In general formula (1), R 8 or R 9 Preferably, one of them is a cyano group.

[0096] In addition to the above, pyrometene derivatives described in International Publication No. 2019 / 146332, International Publication No. 2016 / 190238, International Publication No. 2018 / 101129, International Publication No. 2017 / 002707, and International Publication No. 2020 / 045242 are preferably used.

[0097] Examples of compounds represented by general formula (1) are shown below, but are not limited to these.

[0098] [ka]

[0099] [ka]

[0100] [ka]

[0101] Compounds represented by general formula (1) can be synthesized by referring to the methods described in Japanese Patent Publication No. 8-509471, Japanese Patent Publication No. 2000-208262, J. Org. Chem., vol. 64, No. 21, pp. 7813-7819 (1999), Angew. Chem., Int. Ed. Engl., vol. 36, pp. 1333-1335 (1997), etc.

[0102] The wavelength conversion layer described above may contain other compounds as needed, in addition to the compound represented by general formula (1). For example, an assist dopant such as rubrene may be included to further increase the energy transfer efficiency from excitation light to the compound represented by general formula (1). Furthermore, if it is desired to include emission wavelengths other than those of the compound represented by general formula (1), a desired organic luminescent material can be added, such as a coumarin-based luminescent material, a perylene-based luminescent material, a phthalocyanine-based luminescent material, a stilbene-based luminescent material, a cyanine-based luminescent material, a polyphenylene-based luminescent material, a rhodamine-based luminescent material, a pyridine-based luminescent material, a pyromethene-based luminescent material, a porphyrin-based luminescent material, an oxazine-based luminescent material, or a pyrazine-based luminescent material. In addition to these organic luminescent materials, it is also possible to add a combination of known luminescent materials such as inorganic phosphors, fluorescent pigments, fluorescent dyes, and quantum dots.

[0103] In one embodiment, the first example pyrometene derivative included in the wavelength conversion layer is preferably a pyrometene derivative that exhibits emission observed in the region of peak wavelength between 500 nm and 580 nm when excitation light is used. That is, the wavelength conversion layer preferably comprises a wavelength conversion layer containing the following luminescent material (a). The luminescent material (a) is a luminescent material that exhibits emission observed in the region of peak wavelength between 500 nm and 580 nm when excitation light in the wavelength range of 400 nm and 500 nm is used. Hereafter, emission observed in the region of peak wavelength between 500 nm and 580 nm will be referred to as "green wavelength emission".

[0104] Furthermore, in one embodiment, the second example pyrometene derivative included in the wavelength conversion layer is preferably a pyrometene derivative that exhibits emission observed in the region of peak wavelength between 580 nm and 750 nm when excitation light is used. That is, the wavelength conversion layer preferably comprises a wavelength conversion layer containing the following luminescent material (b). The luminescent material (b) is a luminescent material that exhibits emission observed in the region of peak wavelength between 580 nm and 750 nm when excited by at least one of excitation light in the wavelength range of 400 nm to 500 nm and emission from the above-mentioned luminescent material (a). Hereafter, emission observed in the region of peak wavelength between 580 nm and 750 nm will be referred to as "red wavelength emission".

[0105] Furthermore, in one embodiment, the wavelength conversion member preferably contains the above-mentioned light-emitting material (a) and light-emitting material (b). That is, the wavelength conversion member preferably comprises a wavelength conversion layer (green wavelength conversion layer) containing light-emitting material (a) and a wavelength conversion layer (red wavelength conversion layer) containing light-emitting material (b). In addition, it is preferable that at least one of these light-emitting materials (a) and light-emitting material (b) is the above-mentioned pyromethene derivative. Note that the light-emitting material (a) may be used alone or in combination of multiple types. Similarly, the light-emitting material (b) may be used alone or in combination of multiple types.

[0106] When both a light-emitting material (a) that emits green light and a light-emitting material (b) that emits red light are included, a portion of the green light emission is converted to red light emission. Therefore, it is preferable that the content wa of light-emitting material (a) and the content wb of light-emitting material (b) are in the relationship wa ≥ wb, and the content ratio of each material is preferably wa:wb = 1000:1 to 1:1, more preferably 500:1 to 2:1, and even more preferably 200:1 to 3:1. wa and wb are mass percentages relative to the mass of the wavelength conversion layer.

[0107] A portion of the excitation light in the wavelength range of 400 nm to 500 nm usually passes through parts of the wavelength conversion member other than the wavelength conversion layer (for example, recesses where the wavelength conversion layer is not formed). Therefore, this transmitted portion of excitation light can be used as blue wavelength emission itself. Accordingly, if the wavelength conversion member contains an emissive material (a) that emits green wavelength light and an emissive material (b) that emits red wavelength light in each wavelength conversion layer, and a blue wavelength light source that emits blue wavelength light with a sharp emission peak (for example, a blue wavelength organic EL element or a blue wavelength LED) is used as the light source, it is possible to obtain white wavelength light with good wavelength purity, exhibiting an emission spectrum with sharp shapes at each of the blue, green, and red wavelengths.

[0108] <Light scattering particles> The above wavelength conversion member may contain light-scattering particles. The light-scattering particles may be contained in the binder or in the matrix. From the perspective of ease of molding the microparticles, it is preferable that the light-scattering particles are contained in the binder.

[0109] Light-scattering particles are particles with a particle diameter of 0.1 μm or larger. From the viewpoint of scattering effect, the particle diameter of the light-scattering particles is preferably in the range of 0.5 to 15.0 μm, and more preferably in the range of 0.7 to 12.0 μm. Furthermore, in order to further improve brightness and / or to adjust the brightness distribution with respect to the viewing angle, two or more types of light-scattering particles with different particle sizes may be mixed and used. If we refer to particles with a large particle size as large-diameter particles and particles with a smaller particle size than large-diameter particles as small-diameter particles, then from the viewpoint of imparting external scattering and anti-Newton ring properties, the particle size of the large-diameter particles is preferably in the range of 5.0 μm to 15.0 μm, and more preferably in the range of 6.0 μm to 12.0 μm. Similarly, from the viewpoint of imparting internal scattering properties, the particle size of the small-diameter particles is preferably in the range of 0.5 μm to 5.0 μm, and more preferably in the range of 0.7 μm to 3.0 μm. In addition, the above-mentioned microparticles may also serve as light-scattering particles.

[0110] The haze of the above wavelength conversion member shall be a value measured in accordance with JIS K 7136:2000. An example of a measuring device is the NDH2000 haze meter manufactured by Nippon Denshoku Industries Co., Ltd. From the viewpoint of increasing the amount of emitted light, it is desirable for the above wavelength conversion member to have a high haze, preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more. From the viewpoint of suppressing a decrease in transmittance, it is preferable for the haze to be 98% or less.

[0111] Light-scattering particles may be organic particles, inorganic particles, or organic-inorganic composite particles. For example, synthetic resin particles can be used as organic particles. Specific examples include silicone resin particles, acrylic resin particles (polymethyl methacrylate (PMMA)), nylon resin particles, styrene resin particles, polyethylene particles, urethane resin particles, and benzoguanamine particles. From the viewpoint of ease of obtaining particles with a suitable refractive index, silicone resin particles and acrylic resin particles are preferred. Particles with a hollow structure can also be used. Examples of inorganic particles include elemental metals such as tungsten, zirconium, titanium, platinum, bismuth, rhodium, palladium, silver, tin, platinum, and gold; metal oxides such as silica, barium sulfate, barium carbonate, calcium carbonate, talc, clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, alumina white, titanium oxide, magnesium oxide, barium oxide, aluminum oxide, bismuth oxide, zirconium oxide, and zinc oxide; metal carbonates such as magnesium carbonate, barium carbonate, bismuth subcarbonate, and calcium carbonate; metal hydroxides such as aluminum hydroxide; and composite oxides such as barium zirconate, calcium zirconate, calcium titanate, barium titanate, and strontium titanate, as well as metal salts such as bismuth subnitrate. From the viewpoint of being superior in improving external quantum efficiency, the light scattering particles preferably include at least one selected from the group consisting of titanium dioxide, alumina, zirconium oxide, zinc oxide, calcium carbonate, barium sulfate, barium titanate, and silica, and more preferably include at least one selected from the group consisting of titanium dioxide, zirconium oxide, zinc oxide, and barium titanate.

[0112] The shape of the light scattering particles can be any shape, such as spherical, filamentous, or irregular. It is preferable to use particles with less directional shape (for example, spherical or tetrahedral particles) as the light scattering particles, as this can further improve the uniformity, fluidity, and light scattering properties of the wavelength conversion layer forming composition.

[0113] Inorganic particles may have at least a portion of their surface covered with other components, such as inorganic substances like alumina, silica, zinc oxide, titanium oxide, and zirconium oxide, or organic substances like stearic acid and polysiloxane. For example, 50% or more of the surface of a light-scattering particle may be covered with other components, or the entire surface of a light-scattering particle may be covered with other components. In this case, the light-scattering particle can also be referred to as a surface-treated light-scattering particle.

[0114] One method for covering at least a portion of the surface of light-scattering particles with alumina (i.e., surface-treating with alumina) is a wet treatment method (for example, a method in which an aluminum salt aqueous solution is added to a light-scattering particle slurry and the solution is neutralized to adsorb alumina onto the surface of the light-scattering particles). As light scattering particles, commercially available products such as "MPT-141", "CR-50", "CR-50-2", "CR-58", "CR-58-2", "CR-60", "CR-60-2", and "CR-97" from Ishihara Sangyo Co., Ltd., "MT-700B", "JR-405", "JR-603", "JR-605", "JR-701", "JR-805", and "JR-806" from Teika Co., Ltd., "Ti-pure R-706" from Chemours, "ST-705SA", "ST-710EC", and "ST-750EC" from Titanium Industry Co., Ltd., and "D-918" and "D-970" from Sakai Chemical Industry Co., Ltd. can also be used.

[0115] A large difference in refractive index between the light-scattering particles and the matrix of the wavelength conversion layer is desirable from the viewpoint of scattering effect. From this point of view, the refractive index difference Δn between the light-scattering particles and the matrix is ​​preferably 0.02 or more, more preferably 0.10 or more, and even more preferably 0.20 or more. In this invention and specification, the refractive index n is the value measured at the D line (589 nm). D This indicates.

[0116] The content of light scattering particles in the wavelength conversion layer is preferably 0.5 volume% or more, more preferably 10 volume% to 70 volume%, and even more preferably 20 volume% to 60 volume%, from the viewpoint of the light scattering properties and brittleness of the wavelength conversion layer.

[0117] <Polymer dispersant> The wavelength conversion layer forming composition may contain a polymeric dispersant to enhance the dispersion stability of light scattering particles. The polymeric dispersant is a polymer compound having a weight-average molecular weight of 750 or more and containing a functional group that has affinity for light scattering particles. The polymeric dispersant has the function of dispersing light scattering particles. The polymeric dispersant is adsorbed onto the light scattering particles via the functional group that has affinity for the light scattering particles, and the light scattering particles can be dispersed in the wavelength conversion layer forming composition by electrostatic repulsion and / or steric repulsion between the polymeric dispersants. It is preferable that the polymeric dispersant binds to the surface of the light scattering particles and is adsorbed onto the light scattering particles.

[0118] Examples of functional groups that have affinity for light scattering particles include acidic functional groups, basic functional groups, and non-onic functional groups. Acidic functional groups have dissociable protons and may be neutralized by bases such as amines and hydrate ions. Basic functional groups may be neutralized by acids such as organic acids and inorganic acids.

[0119] <Other additives> In addition to pyromethene derivatives, binders, and matrices, the above-mentioned wavelength conversion members may contain antioxidants, processing and heat stabilizers, lightfastness stabilizers such as ultraviolet absorbers, dispersants for stabilizing the coating film, leveling agents, plasticizers, crosslinking agents such as epoxy compounds, curing agents such as amines, acid anhydrides, and imidazoles, adhesion aids such as silane coupling agents as surface modifiers for the members, and other additives such as silica particles, silicone microparticles, inorganic particles, light scattering particles, and silane coupling agents as sedimentation inhibitors for pyromethene derivatives.

[0120] Examples of antioxidants include phenolic antioxidants such as 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-ethylphenol. However, the antioxidants are not limited to these. These antioxidants may be used individually or in combination.

[0121] Examples of processing and heat stabilizing agents include phosphorus-based stabilizers such as tributyl phosphite, tricyclohexyl phosphite, triethylphosphine, and diphenylbutylphosphine. However, the agents are not limited to these. These stabilizers may be used individually or in combination.

[0122] Examples of light-resistant stabilizers include benzotriazoles such as 2-(5-methyl-2-hydroxyphenyl)benzotriazole and 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole. However, the list is not limited to these. These light-resistant stabilizers may be used individually or in combination.

[0123] These additives are preferably small in the visible light range, from the viewpoint of not interfering with the light from the light source and / or the emission of light from the light-emitting material. Specifically, across the entire wavelength range from 400 nm to 800 nm, the molar extinction coefficient ε of these additives is preferably 1000 or less, more preferably 500 or less, even more preferably 200 or less, and even more preferably 100 or less.

[0124] Furthermore, compounds that act as singlet oxygen quenchers can also be suitably used as lightfastness stabilizers. A singlet oxygen quencher is a material that traps and inactivates singlet oxygen, which is produced when oxygen molecules are activated by light energy. The presence of a singlet oxygen quencher in the wavelength conversion layer prevents the luminescent material from degrading due to singlet oxygen.

[0125] Singlet oxygen is known to be produced through the exchange of electrons and energy between the triplet excited state of dyes such as rose bengal and methylene blue, and the ground state oxygen molecule.

[0126] The above-mentioned wavelength conversion component can perform color conversion (i.e., wavelength conversion) of light by exciting the pyromethene derivative contained in the wavelength conversion layer with excitation light, and emitting light of a different wavelength than the excitation light. As this excitation-emission cycle is repeated, the probability of singlet oxygen being generated increases due to the interaction between the generated excited species and the oxygen contained in the wavelength conversion layer. Therefore, the probability of collisions between the pyromethene derivative and singlet oxygen also increases, leading to accelerated degradation of the pyromethene derivative.

[0127] Pyromethene derivatives are organic luminescent materials. Organic luminescent materials are more susceptible to the effects of singlet oxygen than inorganic luminescent materials. In particular, compounds represented by general formula (1) have higher reactivity with singlet oxygen than compounds having condensed aryl rings such as perylene and their derivatives, and are therefore more significantly affected by singlet oxygen in terms of durability. By rapidly inactivating the generated singlet oxygen with a singlet oxygen quencher, the durability of compounds represented by general formula (1), which have excellent luminescence quantum yield and color purity, can be improved.

[0128] Examples of compounds that act as singlet oxygen quenchers include tertiary amines, catechol derivatives, and nickel compounds. However, the list is not limited to these. Furthermore, these compounds (light-resistant stabilizers) may be used individually or in combination.

[0129] <Base material> As the base material 28, various film-like materials (sheet-like materials) used in known wavelength conversion members can be used. In the present invention and this specification, film and sheet are synonymous. As the base material 28, various film-like materials capable of supporting the wavelength conversion layer 26 and the wavelength conversion layer forming composition that will become the wavelength conversion layer 26 can be used. The base material 28 is preferably transparent, and for example, glass, transparent inorganic crystalline material, transparent resin material, etc. can be used as the base material 28. Furthermore, the base material 28 may be rigid or flexible. In addition, the base material 28 may be in the form of a long length that can be wound, or it may be in the form of a sheet that has been cut to a predetermined size in advance.

[0130] As the base material 28, films made of various resin materials (polymer materials) are preferably used because they are easy to thin, easy to lighten, and suitable for flexibility. Specifically, resin films made of polyethylene (PE), polyethylene naphthalate (PEN), polyamide (PA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyimide (PI), transparent polyimide, polymethyl methacrylate resin (PMMA), polycarbonate (PC), polyacrylate, polymethacrylate, polypropylene (PP), polystyrene (PS), ABS, cycloolefin copolymer (COC), cycloolefin polymer (COP), and triacetylcellulose (TAC) are preferably exemplified. Furthermore, gas barrier films, which have a gas barrier layer forming on these resin films to exhibit gas barrier properties, can also be used as the substrate 28.

[0131] Here, the substrate 28 has an oxygen permeability of 0.1 to 100 cc / (m³). 2 It is preferable that it is 1-50cc / (m) (day·atm), 2 A value of (day·atm) is more preferable. Note that the SI unit for oxygen permeability is [fm / (s·Pa)]. [cc / (m 2·day·atm)] is ``1fm / (s·Pa)=8.752cc / (m 2 It can be converted to SI units using 'day·atm'.

[0132] The oxygen permeability of substrate 28 is 100 cc / (m³). 2 Having a temperature of less than or equal to (day·atm) is preferable in that it can effectively prevent the degradation of the pyromethene derivative 38 by oxygen and prevent the degradation of the binder 32.

[0133] Furthermore, films with low oxygen permeability, i.e., films with high gas barrier properties, are dense and high-density films, or films having dense and high-density layers. Generally, such films include those in which a layer of metal oxides or metal nitrides, with a thickness of several tens to several hundreds of nanometers, is formed on a support film. However, films containing such inorganic materials may degrade the optical properties of the wavelength conversion member 16 due to light absorption by the inorganic layer. Also, chemical vapor deposition (CVD) and physical vapor deposition (PVD) are commonly used to form the inorganic layer. However, due to the low production rate and the extremely high level of quality control required for foreign matter and other contaminants, films containing such inorganic materials are generally expensive. In contrast, the oxygen permeability of the substrate 28 is 0.1 cc / (m³). 2 By setting the temperature to (day·atm) or higher, it is possible to select films made by wet processes such as solution coating or spray coating, and since there is no need to have a dense inorganic layer, it is preferable in that the optical properties of the wavelength conversion member 16 can be prevented from degrading due to the substrate 28, and the cost of the wavelength conversion member 16 can be reduced.

[0134] Furthermore, the substrate 28 may optionally include one or more layers such as a hard coat layer, an anti-Newton ring layer, an anti-reflective layer, a low-reflection layer, or an anti-glare layer, or it may include one or more surface layers such as a light scattering layer, a primer layer, an antistatic layer, or an undercoat layer together with (or instead of) these layers.

[0135] The wavelength conversion member 16 shown in Figure 2 has a configuration in which the wavelength conversion layer 26 is sandwiched between base materials 28, corresponding to both main surfaces of the wavelength conversion layer 26. However, the present invention is not limited thereto. That is, the wavelength conversion member 16 may have a configuration in which the base material 28 is provided on only one main surface of the wavelength conversion layer 26. The main surface refers to the largest surface of a layer or film-like material. The wavelength conversion member 16 is preferably configured in which the wavelength conversion layer 26 is sandwiched between base materials 28 in terms of being able to suitably protect the wavelength conversion layer 26, preventing degradation of the pyromethene derivative 38 by oxygen, and suppressing physical deformation such as curling and bending by increasing the rigidity of the wavelength conversion member 16.

[0136] When the wavelength conversion layer 26 is sandwiched between substrates 28, the two substrates may be the same or different. When the wavelength conversion layer 26 is sandwiched between substrates 28, if the two substrates are different, it is preferable that at least one of the substrates 28 satisfies the aforementioned oxygen permeability requirement, and it is more preferable that both substrates satisfy the aforementioned oxygen permeability requirement. Furthermore, the thickness of the substrate 28 is preferably in the range of 5 to 150 μm, more preferably in the range of 10 to 70 μm, and even more preferably in the range of 15 to 55 μm. A substrate thickness of 5 μm or more is preferable in that it can suitably hold and protect the wavelength conversion layer 26, prevent degradation of the pyromethene derivative 38 by oxygen, and suppress physical deformation such as curling and bending by increasing the rigidity of the wavelength conversion member 16. A substrate thickness of 150 μm or less is preferable in that it can reduce the overall thickness of the wavelength conversion member 16 including the wavelength conversion layer 26.

[0137] There are no particular limitations on the method for manufacturing such a wavelength conversion member 16, and various known methods for manufacturing a laminated film in which a layer exhibiting optical functionality is sandwiched between resin films or supported on one side can be used. The following methods are examples of preferred methods for manufacturing the wavelength conversion member 16.

[0138] A dispersion is prepared by adding a pyrometene derivative to a liquid compound that will form the matrix 36, such as an uncured (meth)acrylate monomer, and then adding a polymerization initiator or the like as needed, and stirring the mixture to disperse the pyrometene derivative in the liquid compound that will form the matrix 36. The content of the pyrometene derivative in this dispersion will be the content of the pyrometene derivative in the formed microparticles 34.

[0139] On the other hand, an aqueous solution of the binder is prepared by dissolving a compound that will become the binder 32, such as PVA, in water. It is preferable to use pure water or deionized water. There are no particular limitations on the concentration of this aqueous solution, and it can be set appropriately depending on the compound that will become the binder 32, the amount of dispersion added (described later), etc. The concentration of this aqueous solution is preferably 1 to 40% by mass, and more preferably 5 to 20% by mass.

[0140] Next, the aforementioned dispersion is added to an aqueous solution of binder 32 dissolved in water, and if necessary, an emulsifier or the like is added and stirred to prepare an emulsified solution by dispersing the dispersion in the aqueous solution. As mentioned above, the liquid compound that becomes the matrix 36 is usually hydrophobic, and the pyromethene derivative is also hydrophobic. Furthermore, the binder 32 preferably has an oxygen permeability coefficient of 0.01 cc / (m³). 2 It is less than or equal to (day·atm) and therefore hydrophilic. For this reason, the dispersion is dispersed in an aqueous solution in the form of droplets containing the pyromethene derivative within droplets of the matrix compound 36.

[0141] After preparing the emulsion, the compound that will become the matrix 36 in the dispersion is cured (crosslinked, polymerized) by methods such as ultraviolet irradiation or heating while the emulsion is being stirred. As a result, microparticles 34 in which pyromethene derivative 38 is dispersed in the matrix 36 are formed, and a coating solution (i.e., a composition for forming a wavelength conversion layer) is prepared by dispersing the microparticles 34 in an aqueous solution of binder 32 and emulsifying it.

[0142] On the other hand, two substrates 28, such as PET film, are prepared. After preparing the coating solution and preparing the substrate 28, the coating solution is applied to one surface of one substrate 28, and the coating solution is heated and dried to form the wavelength conversion layer 26. The coating solution for forming the aforementioned wavelength conversion layer 26G and the coating solution for forming the wavelength conversion layer 26R are applied in order and dried to produce the laminate 26Y. Alternatively, a wavelength conversion layer-forming composition containing microparticles 34G and microparticles 34R is applied and dried to form a wavelength conversion layer 26. There are no particular limitations on the method of applying the coating solution; various known coating methods such as spin coating, die coating, bar coating, and spray coating can be used. There are also no particular limitations on the method of heating and drying the coating solution; various known methods for drying aqueous solutions can be used, such as heating and drying using a heater, heating and drying using hot air, and heating and drying using both a heater and hot air.

[0143] Once the wavelength conversion layer 26 (or laminate 26Y) is formed, another substrate 28 can be laminated and attached to the surface of the wavelength conversion layer 26 that does not have another substrate 28, thereby creating the wavelength conversion member 16 shown in Figure 2. This attachment of the substrate 28 may be performed using the tackiness or adhesiveness of the wavelength conversion layer 26, or, if necessary, using a transparent adhesive, transparent adhesive sheet, optical clear adhesive (OCA), or other adhesive, adhesive layer, or adhesive sheet. Furthermore, when manufacturing a wavelength conversion member in which the substrate 28 is provided only on one main surface of the wavelength conversion layer 26, the manufacturing of the wavelength conversion member can be completed when the coating solution is heated and dried to form the wavelength conversion layer 26.

[0144] In the backlight unit 10, a light source 18 is positioned at the center of the bottom surface inside the housing 14. The light source 18 is the light source emitted by the backlight unit 10. Any known light source can be used as the light source 18, as long as it emits light having a wavelength that is converted by the pyrometene derivative 38 of the wavelength conversion member 16 (wavelength conversion layer 26). Among these, LEDs (Light Emitting Diodes) are preferably exemplified as light sources 18. Furthermore, as mentioned above, a wavelength conversion layer 26 of the wavelength conversion member 16 is preferably made by dispersing microparticles containing pyromethene derivatives in a binder such as resin. For this reason, blue LEDs that emit blue light are particularly preferably used as light sources 18, and among them, blue LEDs with a peak wavelength of 450 nm ± 50 nm are particularly preferably used.

[0145] In the backlight unit 10, there are no particular limitations on the output of the light source 18; it can be set appropriately according to the required illuminance (brightness) of the light in the backlight unit 10. Furthermore, in the backlight unit 10, the light source 18 may be one, as shown in the illustrated example, or multiple light sources 18 may be provided.

[0146] The backlight unit 10 shown in Figure 1 is a so-called direct-lit backlight unit. However, the present invention is not limited to this, and can also be suitably used in so-called edge-lit backlight units that use a light guide plate. In the case of an edge-lit backlight unit, for example, one main surface of the wavelength conversion member 16 can be placed facing the light incident surface of the light guide plate, and the light source 18 can be placed on the opposite side of the wavelength conversion member 16 from the light guide plate to constitute an edge-lit backlight unit. In an edge-lit backlight unit, the light source 18 is usually arranged in multiple units along the longitudinal direction of the light incident surface of the light guide plate, or a long light source is arranged with its longitudinal direction aligned with the longitudinal direction of the light incident surface of the light guide plate.

[0147] <Barrier film> A barrier film may be appropriately used in the above wavelength conversion member. Examples of such barrier films include inorganic oxides such as silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, zinc oxide, tin oxide, indium oxide, yttrium oxide, and magnesium oxide; inorganic nitrides such as silicon nitride, aluminum nitride, titanium nitride, and silicon carbide nitride; mixtures thereof; metal oxide thin films or metal nitride thin films with other elements added to these; or films made of various resins such as polyvinyl chloride resin, acrylic resin, silicone resin, melamine resin, urethane resin, fluororesin, and polyvinyl alcohol resin such as saponified vinyl acetate.

[0148] Suitable barrier resins for use in barrier films include, for example, polyester, polyvinyl chloride, nylon, polyvinyl fluoride, polyvinylidene chloride, polyacrylonitrile, polyvinyl alcohol, ethylene-vinyl alcohol copolymers, and mixtures of these resins. Among these, polyvinylidene chloride, polyacrylonitrile, ethylene-vinyl alcohol copolymers, and polyvinyl alcohol have very low oxygen permeability coefficients, so barrier films containing one or more of these resins are preferred. From the viewpoint of resistance to discoloration, it is even more preferable for the barrier film to contain one or more of polyvinylidene chloride, polyvinyl alcohol, and ethylene-vinyl alcohol copolymers, and from the viewpoint of low environmental impact, it is particularly preferable to contain polyvinyl alcohol or ethylene-vinyl alcohol copolymers. These resins may be used individually or mixed with different resins. From the viewpoint of uniformity and cost of the barrier film, a barrier film made of a single resin is more preferable.

[0149] As the polyvinyl alcohol, for example, a saponified polyvinyl acetate in which 98 mol% or more of acetyl groups have been saponified can be used. As the ethylene-vinyl alcohol copolymer, for example, a saponified ethylene-vinyl acetate copolymer with an ethylene content of 20-50% in which 98 mol% or more of acetyl groups have been saponified can be used.

[0150] Furthermore, commercially available resins and films can be used. Specific examples of commercially available products include Kuraray's polyvinyl alcohol resin PVA117, Kuraray's ethylene-vinyl alcohol copolymer ("EVAL" registered trademark) resins L171B and F171B, and film EF-XL.

[0151] The barrier film may contain, as needed, antioxidants, curing agents, crosslinking agents, processing and heat stabilizers, UV absorbers, and other light-resistant stabilizers, to the extent that they do not excessively affect the luminescence and durability of the wavelength conversion layer.

[0152] There are no particular limitations on the thickness of the barrier film. From the viewpoint of the overall flexibility of the wavelength conversion member and / or cost, the thickness of the barrier film is preferably 100 μm or less. More preferably 50 μm or less, and even more preferably 20 μm or less. Particularly preferably 10 μm or less, and may be 1 μm or less. However, from the viewpoint of ease of layer formation, it is preferably 0.01 μm or more.

[0153] The barrier film may be provided on both sides of the wavelength conversion member, or on only one side. Furthermore, depending on the functions required of the wavelength conversion member, an auxiliary layer having anti-reflective function, anti-glare function, anti-reflective anti-glare function, hard coat function (abrasion resistance function), antistatic function, anti-fouling function, electromagnetic wave shielding function, infrared cut function, ultraviolet cut function, polarization function, color tuning function, etc. may be provided.

[0154] <Organic layer> The above wavelength conversion member may consist only of a substrate and a wavelength conversion layer, or only of a substrate, a wavelength conversion layer, and a barrier film, or it may have one or more additional layers. An example of such layers is an organic layer. An "organic layer" is a layer whose main component is an organic substance. The organic layer may be a layer in which the content of organic substances is 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more. Alternatively, it may be a layer composed only of organic substances. Here, a layer composed only of organic substances means a layer that contains only organic substances, excluding impurities that are inevitably mixed in during the manufacturing process. In the organic layer, only one type of organic substance may be included, or two or more types may be included.

[0155] For details on the organic layer, see paragraphs 0020 to 0042 of Japanese Patent Publication No. 2007-290369 and paragraphs 0074 to 0105 of Japanese Patent Publication No. 2005-096108. In one embodiment, the organic layer may include a cardopolymer. This is preferable because it strengthens the adhesion between the organic layer and adjacent layers, particularly with the inorganic layer. For details on the cardopolymer, see paragraphs 0085 to 0095 of Japanese Patent Publication No. 2005-096108.

[0156] Furthermore, an organic layer containing a (meth)acrylamide compound is also preferred as the organic layer. It is preferable to provide the organic layer containing the (meth)acrylamide compound between the barrier film and the wavelength conversion layer from the viewpoint of increasing the adhesion between these layers. In the present invention and this specification, "(meth)acrylamide compound" refers to a compound containing one or more (meth)acrylamide groups in one molecule. "(meth)acrylamide group" is used to indicate either or both an acrylamide group and a methacrylamide group. An acrylamide group is a monovalent group represented as "CH2=CH-(C=O)-NH-", and a methacrylamide group is a monovalent group represented as "CH2=C(CH3)-(C=O)-NH-". The functional number for a "(meth)acrylamide compound" refers to the number of (meth)acrylamide groups contained in one molecule of this compound. With respect to (meth)acrylamide compounds, "monofunctional" means that the number of (meth)acrylamide groups in one molecule is one, and "polyfunctional" means that the number of (meth)acrylamide groups in one molecule is two or more. Polyfunctional (meth)acrylamide compounds are preferred, and bifunctional to tetrafunctional compounds are more preferred. For specific examples of (meth)acrylamide compounds, see, for example, paragraphs 0069 to 0070 of International Publication No. 2019 / 004431.

[0157] An organic layer containing a (meth)acrylamide compound can be formed using a polymerizable composition containing a (meth)acrylamide compound. The (meth)acrylamide compound is a polymerizable compound, and the polymerizable composition may contain one or more (meth)acrylamide compounds as polymerizable compounds. The polymerizable composition may contain known polymerization initiators. The polymerization initiator is not particularly limited, and for example, paragraph 0079 of International Publication No. 2019 / 004431 can be referenced.

[0158] The organic layer can be formed on the barrier film surface, the substrate surface, or the wavelength conversion layer surface by a known film-forming method using a polymerizable composition. The thickness of the organic layer is preferably in the range of 0.05 to 10.00 μm, and more preferably in the range of 0.50 to 5.00 μm. [Examples]

[0159] The present invention will be described in more detail below based on examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following specific examples.

[0160] [Example 1] <Preparation of dispersion A> A toluene dispersion with the following composition was prepared, and the resulting solution was heated under reduced pressure at 40°C using an evaporator to remove the toluene, thereby preparing a dispersion in which a pyromethene derivative was dispersed in a matrix. Pyromethene derivative G-1 (emission maximum: 530 nm) 1% by mass Dicyclopentanyl acrylate (DCP) (manufactured by Hitachi Chemical Co., Ltd., FA-513AS) 97% by mass Photopolymerization initiator (BASF, Irgacure TPO) 2% by mass

[0161] <Preparation of dispersion B> Dispersion B was prepared in the same manner as dispersion A, except that pyromethene derivative G-1 was replaced with pyromethene derivative R-1 (emission maximum: 630 nm) and its content was set to 0.2% by mass.

[0162] [ka]

[0163] <Preparation of binder aqueous solution> As the binder for the wavelength conversion layer, PVA (partially saponified polyvinyl alcohol PVA203, manufactured by Kuraray Co., Ltd., SP value = 25.1 (cal / cm²)) is used. 3 ) 0.5 We prepared a solution with a saponification degree of 87-89 mol% and Mw of 16,000. This binder was added to pure water and stirred while heating to a liquid temperature of 80°C to dissolve it, thereby preparing an aqueous binder solution in which the binder (PVA) was dissolved in pure water. The binder concentration in the aqueous binder solution was 30% by mass. The oxygen permeability coefficient of this binder was measured using the following procedure. The prepared binder aqueous solution was applied to a PET film (Toyobo Co., Ltd., CosmoShine A4300, 50 μm thick) and heated and dried in a heating furnace at 95°C for 30 minutes. The resulting coating film thickness was 10 μm. The coating film was peeled off the PET film and measured using a MOCON method measuring device (MOCON Corporation, OX-TRAN 2 / 21) under conditions of 25°C and 60% relative humidity. The oxygen permeability coefficient of the binder was as shown in Table 1.

[0164] <Preparation of Emulsified Solution A and Coating Solution A> Using the prepared dispersion A and binder aqueous solution, a mixture with the following composition was prepared. Dispersion liquid A 5.8 parts by mass Binder aqueous solution: 93.7 parts by mass 0.5 parts by mass of a 1% by mass aqueous solution of sodium dodecyl sulfate (manufactured by Tokyo Chemical Co., Ltd., SDS) 50 ml of the above-described mixture and a magnetic stirrer (hereinafter referred to as "stirrer") were placed into a 35 mm diameter vial. All preparation of the mixture was carried out in a glove box with an oxygen concentration of 300 ppm (parts per million) or less. Furthermore, the vial was sealed inside the glove box, and the interior was kept under nitrogen purging. Emulsified solution A was prepared by removing the vial containing the mixture and stirrer from the glove box and stirring it with the stirrer at 1500 rpm (revolutions per minute) for 30 minutes. Next, while stirring emulsion A to maintain its emulsified state, ultraviolet light was irradiated onto the entire emulsion A using a 160 W / cm air-cooled metal halide lamp (manufactured by I-Graphics Co., Ltd.) to cure the matrix (DCP) of the dispersion and form microparticles. This prepared coating solution A, in which the microparticles were dispersed and emulsified in an aqueous solution of binder (PVA). The ultraviolet irradiation time was 120 seconds. Furthermore, the microparticle matrix was cured under exactly the same conditions, and the oxygen permeability coefficient of the matrix was measured in the same way as the binder. As a result, the oxygen permeability coefficient of the matrix was 39 (cc·mm) / (m 2 It was ·day·atm).

[0165] <Preparation of Emulsified Solution A and Coating Solution A> Emulsion B was prepared in the same manner as emulsion A, except that dispersion A was replaced with dispersion B. Using the obtained emulsion B, coating solution B was prepared in the same manner as coating solution A.

[0166] <Fabrication of wavelength conversion components> Two sheets of 50 μm thick PET film (Toyobo Co., Ltd., CosmoShine A4300) were prepared as the base material. The prepared coating solution A was applied to one surface of one substrate using a die coater. Next, the coating solution was dried in a heating furnace at a furnace temperature of 95°C for 30 minutes to form a wavelength conversion layer A on the substrate. The thickness of the formed wavelength conversion layer A was 22 μm.

[0167] Next, coating solution B was applied to the formed wavelength conversion layer A using a die coater to form wavelength conversion layer B in the same manner as wavelength conversion layer A. The thickness of the formed wavelength conversion layer B was 13 μm.

[0168] The obtained wavelength conversion layer A was cut using a microtome to form a cross-section, and when examined with an optical microscope (reflected light), it was found that the wavelength conversion layer contained microparticles in which a phosphor (pyrometene derivative) was dispersed in the matrix. Furthermore, when the optical microscope images obtained using this procedure were analyzed with image analysis software (ImageJ), the average particle size of the microparticles was 5 μm, and the microparticle content in wavelength conversion layer A was 17 volume%.

[0169] A wavelength conversion member 101, as shown in Figure 2, was fabricated by laminating the other substrate (PET film) onto the formed wavelength conversion layer B and attaching it with an adhesive (3M Corporation, 8172CL), thereby sandwiching the wavelength conversion layer (a laminate of wavelength conversion layers A and B) between two substrates.

[0170] [Example 2] In Example 1, dispersion A, emulsion A, and coating A were prepared in the same manner as in Example 1, except that pyrometene derivative G-1 was replaced with G-2, and a wavelength conversion member 102 with a wavelength conversion layer A was fabricated.

[0171] [Example 3] Wavelength conversion member 103 was fabricated in the same manner as in Example 1, except that the binder of the wavelength conversion layer was changed from PVA (PVA203) to vinyl alcohol-butenediol copolymer (BVOH, manufactured by Nippon Synthetic Chemical Co., Ltd., G Polymer (AZF8035W)). The particle size of the microparticles was measured in the same manner as in Example 1, and the average particle size of the microparticles was 5 μm. Furthermore, the oxygen permeability coefficient of the binder was measured in the same manner as in Example 1, and the values ​​are shown in Table 1.

[0172] [Example 4] In preparing the coating solution, the emulsifier to be added was changed from SDS to BRIJ 30 (polyethylene glycol dodecyl ether, HLB value 10.7) manufactured by Sigma-Aldrich, and the amount of emulsifier added was adjusted so that the emulsifier content in the wavelength conversion layer was as shown in Table 1. Otherwise, the wavelength conversion member 104 was prepared in the same manner as in Example 1. When the particle size of the microparticles was measured in the same manner as in Example 1, the average particle size of the microparticles was found to be 9 μm.

[0173] [Example 5] The wavelength conversion member 105 was fabricated in the same manner as in Example 1, except that the PVA used as the binder for the wavelength conversion layer was changed from PVA203 to PVA505 manufactured by Kuraray Co., Ltd. The particle size of the microparticles was measured in the same manner as in Example 1, and the average particle size of the microparticles was 3 μm. Furthermore, the oxygen permeability coefficient of the binder was measured in the same manner as in Example 1, and the values ​​are shown in Table 1.

[0174] [Comparative Example 1] To prepare the binder resin, 100 parts by mass of polymethyl methacrylate (PMMA, manufactured by Kuraray Co., Ltd.) was mixed with 0.25 parts by mass of pyromethene derivative G-1 and 300 parts by mass of toluene as a solvent. These mixtures were then stirred and defoamed at 300 rpm for 20 minutes using a planetary stirring and defoaming device "Mazelstar" KK-400 (manufactured by Kurabo Corporation) to obtain composition A for forming the wavelength conversion layer A. The oxygen permeability coefficient of PMMA was 6000 (cc·mm) / (m³). 2 It was ·day·atm). Furthermore, composition B for preparing wavelength conversion layer B was obtained in the same manner as composition A, except that 0.03 parts by mass of pyromethene derivative R-1 and 300 parts by mass of toluene as a solvent were mixed with 100 parts by mass of polymethyl methacrylate.

[0175] Next, composition A was applied to the 50 μm PET film using a slit die coater, and heated and dried in a heating furnace at a temperature of 100°C for 20 minutes to form a wavelength conversion layer A with an average thickness of 15 μm. Furthermore, composition B was applied to the wavelength conversion layer A and dried to form a wavelength conversion layer B with an average thickness of 13 μm, similar to the wavelength conversion layer A.

[0176] A wavelength conversion member 201 was fabricated by laminating a substrate (PET film) onto the formed wavelength conversion layer B and attaching it with an adhesive (3M, 8172CL), thereby sandwiching the wavelength conversion layer between two substrates.

[0177] [Example 6] In Example 1, the binder was PVA203 (partially saponified polyvinyl alcohol, manufactured by Kuraray Co., Ltd., SP value = 25.1 (cal / cm²)). 3 ) 0.5 From PVA103 (manufactured by Kuraray Co., Ltd., fully saponified polyvinyl alcohol, SP value = 25.6 (cal / cm³)) (saponification degree = 87-89 mol%, Mw = 16,000) 3 ) 0.5 A wavelength conversion member 106 was prepared in the same manner as in Example 1, except that the degree of saponification (98-99 mol%, Mw = 16,000), the emulsifier was changed from SDS to BRIJ30 (Sigma-Aridrich, polyethylene glycol dodecyl ether, HLB value = 10.7), and the amount of emulsifier added was changed to an amount that resulted in the emulsifier content in the wavelength conversion layer being the value shown in the table below. The oxygen permeability coefficient of the binder was measured in the same manner as in Example 1, and the value was as shown in the table below.

[0178] [Example 7] In Example 6, the wavelength conversion member 107 was prepared in the same manner as in Example 6, except that the emulsifier was changed from BRIJ30 to BRIJ35 (manufactured by Sigma-Aridrich, polyoxyethylene (23) lauryl ether, HLB value = 16.9).

[0179] [Example 8] In Example 6, the wavelength conversion member 108 was prepared in the same manner as in Example 6, except that the emulsifier was changed from BRIJ30 to NIKKOL BC-2 (manufactured by Nikko Chemicals Co., Ltd., POE(2) cetyl ether, HLB value = 6.4).

[0180] [Comparative Example 2] In Example 6, the wavelength conversion member 202 was prepared in the same manner as in Example 6, except that an emulsifier was not added. In Comparative Example 2, no microparticles were formed, and the emulsion and the binder aqueous solution were in phase separation.

[0181] [Comparative Example 3] In Example 6, the wavelength conversion member 203 was prepared in the same manner as in Example 6, except that the emulsifier was changed from BRIJ30 to NIKKOL MGO (Nikko Chemicals Co., Ltd., glyceryl oleate, HLB value = 2.5). In Comparative Example 3, no microparticles (i.e., particles with the particle size described above) were obtained, and a large number of coarse particles were observed.

[0182] [Example 9] <Preparation of 109g dispersion> A methyl ethyl ketone dispersion with the following composition was prepared, and a dispersion 109G was prepared by dispersing a pyromethene derivative in the matrix. • Pyromethene derivative G-1 (emission maximum: 530 nm) 1.2% by mass • Polymethyl methacrylate (PMMA) (manufactured by Mitsubishi Gas Chemical Co., Ltd., Dianaal BR-83, SP value = 9.7 (cal / cm³) 3 ) 0.5 , Mw=40,000) 28.8% by mass Methyl ethyl ketone 69% by mass

[0183] <Preparation of dispersion 109R> Dispersion 109R was prepared in the same manner as dispersion 109G, except that pyrometene derivative G-1 in dispersion 109R was replaced with pyrometene derivative R-1, and the content was adjusted to 0.2% by mass.

[0184] <Granulation of microparticles> The prepared dispersion 109G or 109R was stirred for 10 minutes and then granulated using a spray dryer (Yamato Scientific Co., Ltd., model DL-41). The operating conditions were set to an inlet temperature of 140°C and an outlet temperature of 90°C, with a drying air volume of 0.8 m³. 3 The mixture was dried and granulated at a nozzle spray air pressure of 0.1 MPa and a slurry flow rate of 20 g / min. The resulting granules were dried in air (90°C) for 2 minutes. Observation of the obtained powder with an optical microscope confirmed the formation of 3 μm diameter microparticles 10⁹G or 10⁹R in which pyrometene dye was dispersed.

[0185] <Preparation of coating solution 109> A coating solution with the following composition was prepared to obtain coating solution 109. • Binder aqueous solution (prepared using the same procedure as in Example 1) 96.9% by mass • Microparticles 10⁹G 3% by mass • Microparticles 10⁹R 0.1% by mass

[0186] <Fabrication of wavelength conversion components> Two sheets of 50 μm thick PET film (Toyobo Co., Ltd., CosmoShine A4360) were prepared as the base material. The prepared coating solution 109 was applied to one surface of one substrate using a die coater. Next, the coating solution was dried in a constant temperature bath (internal temperature 90°C) for 5 minutes to form a wavelength conversion layer 109 on the substrate. The thickness of the formed wavelength conversion layer 109 was 28 μm.

[0187] The obtained wavelength conversion layer 109 was cut using a microtome to form a cross-section, and when examined with an optical microscope (reflected light), it was found that microparticles were dispersed in the matrix of the wavelength conversion layer. Furthermore, when the optical microscope images obtained using this procedure were analyzed with image analysis software (ImageJ), the average particle size of the microparticles was 3 μm, and the microparticle content in the wavelength conversion layer 109 was 10 volume percent.

[0188] A wavelength conversion member 109, as shown in Figure 2, was fabricated by attaching the other substrate (PET film) to the formed wavelength conversion layer 109 via an adhesive (3M, 8172CL), thereby sandwiching the wavelength conversion layer between two substrates.

[0189] [Example 10] In Example 9, the matrix was changed from Dianal BR-83 (manufactured by Mitsubishi Gas Chemical Company, polymethyl methacrylate) to Estyrene AS-30 (manufactured by Nippon Steel & Sumitomo Metal Chemical Corporation, acrylonitrile-styrene copolymer, SP value = 12.6 (cal / cm²)). 3 ) 0.5 The wavelength conversion member 110 was fabricated in the same manner as in Example 9, except that it was changed to ).

[0190] [Example 11] In Example 9, the matrix was changed from Dianal BR-83 (manufactured by Mitsubishi Gas Chemical Co., Ltd., polymethyl methacrylate) to SGP-10 (manufactured by PS Japan Co., Ltd., polystyrene, SP value = 8.9 (cal / cm²)). 3 ) 0.5 The wavelength conversion member 111 was fabricated in the same manner as in Example 9, except that it was changed to ).

[0191] [Example 12] In Example 9, the binder was PVA203 (manufactured by Kuraray Co., Ltd., partially saponified polyvinyl alcohol, SP value = 25.1 (cal / cm²)). 3 ) 0.5 From PVA103 (manufactured by Kuraray Co., Ltd., fully saponified polyvinyl alcohol, SP value = 25.6 (cal / cm³)) (saponification degree = 87-89 mol%, Mw = 16,000) 3 ) 0.5 A wavelength conversion member 112 was fabricated in the same manner as in Example 9, except that the degree of saponification was changed to 98-99 mol% and Mw was changed to 16,000.

[0192] [Example 13] In Example 12, a wavelength conversion member 113 was prepared in the same manner as in Example 12, except that a 1% by mass aqueous solution of the emulsifier BRIJ30 (manufactured by Sigma-Aridrich, polyethylene glycol dodecyl ether, HLB value = 10.7) was added to the coating solution in an amount such that the emulsifier content in the wavelength conversion layer was as shown in the table below.

[0193] [Comparative Example 4] <Preparation of Binder Aqueous Solution 204> As the binder for the wavelength conversion layer, PVA (partially saponified polyvinyl alcohol PVA203, manufactured by Kuraray Co., Ltd., SP value = 25.1 (cal / cm²)) is used. 3 ) 0.5 We prepared a solution with a saponification degree of 87-89 mol% and Mw of 16,000. This binder was added to a mixed solution of pure water / methanol = 70 parts by mass / 30 parts by mass, and dissolved by stirring while heating to a liquid temperature of 85°C, thereby preparing an aqueous binder solution in which the binder (PVA) was dissolved in pure water. The binder concentration in the aqueous binder solution was 30% by mass.

[0194] <Preparation of dispersions 204G and 204R> A pyrometene derivative dispersion with the following composition was prepared, and dispersions 204G and 204R containing the pyrometene derivative were prepared. (Dispersion liquid 204G) • Pyromethene derivative G-1 (emission maximum: 530 nm) 1.0 mass% • Methanol 99% by mass (Dispersion liquid 204R) • Pyromethene derivative R-1 (emission maximum: 630nm) 1.0% by mass • Methanol 99% by mass

[0195] <Preparation of coating solution 204> A coating solution with the following composition was prepared to obtain coating solution 204. • Binder aqueous solution 204 6.9% by mass ·Dispersion liquid 204G 3% by mass ·Dispersion liquid 204R 0.1% by mass

[0196] <Fabrication of wavelength conversion components> Two sheets of 50 μm thick PET film (Toyobo Co., Ltd., CosmoShine A4360) were prepared as the base material. The prepared coating solution 204 was applied to one surface of one substrate using a die coater. Next, the coating solution was dried in a constant temperature bath (internal temperature 90°C) for 5 minutes to form a wavelength conversion layer 204 on the substrate. The thickness of the formed wavelength conversion layer 204 was 21 μm.

[0197] The obtained wavelength conversion layer 109 was cut using a microtome to form a cross-section, and when examined with an optical microscope (reflected light), it was found that no microparticles were formed in the matrix of the wavelength conversion layer, and pyrometene dye was dispersed in the binder.

[0198] A wavelength conversion member 204 was fabricated as shown in Figure 2, in which the wavelength conversion layer was sandwiched between two substrates by attaching the formed wavelength conversion layer 204 to the other substrate (PET film) via an adhesive (3M, 8172CL).

[0199] <Measurement of initial brightness> A commercially available tablet device (product name "Kindle® Fire HDX 7," manufactured by Amazon) equipped with a blue light source in its backlight unit was disassembled, and the backlight unit was removed. The wavelength conversion material QDEF (Quantum Dot Enhancement Film) that was incorporated into the backlight unit was replaced with a rectangular (50 x 50 mm) wavelength conversion material from the example or comparative example. A backlight unit was thus fabricated. The fabricated backlight unit was turned on so that the entire surface displayed white, and the initial luminance value Y0 (cd / m²) was measured using a luminance meter (TOPCON SR3) placed 520 mm perpendicular to the surface of the light guide plate. 2 The following parameters were measured and evaluated based on the evaluation criteria below. -Evaluation Criteria- S:Y0≧545 A: 545 > Y0 ≥ 530 B: 530 > Y0 ≥ 515 C: 515 > Y0 ≥ 500 D: 500 > Y0

[0200] <Measurement of durability> From the measurement of the aforementioned initial luminance, the backlight unit was continuously lit for 1000 hours, and the luminance was measured in the same manner to obtain the luminance value Y1 after the test. Based on the initial luminance value Y0 and the luminance value Y1 after the test, the durability [%] was calculated by the following formula and evaluated based on the following evaluation criteria. Durability [%] = (Y1 / Y0) × 100 - Evaluation criteria - S: Durability ≥ 97% A: 97 > Durability ≥ 95% B: 95 > Durability ≥ 90% C: 90 > Durability ≥ 80% D: Durability < 80%

[0201]

Table 1

[0202] As shown in Table 1, the wavelength conversion members of Examples 1 to 5 in which the pyromethene derivative is dispersed in the form of microparticles in the wavelength conversion layer can suppress the mixing of different pyromethene derivatives even when the wavelength conversion layer is a laminate, and can maintain excellent emission color purity, so the luminance of white light is good. On the other hand, the member of Comparative Example 1 that does not use microparticles cannot avoid the mixing due to the interlayer movement of the pyromethene derivative during coating and lamination, resulting in a decrease in luminance.

[0203] Also, from the comparison between Examples 1 to 4 and Example 5, it can be confirmed that it is preferable to set the oxygen permeability coefficient of the binder dispersing the microparticles to 0.01 (cc·mm) / (m 2 ·day·atm) or less in order to further improve the durability while maintaining the luminance.

[0204]

Table 2

[0205]

Table 3

Industrial Applicability

[0206] One aspect of the present invention is useful in the technical field of liquid crystal display devices.

Explanation of Signs

[0207] 10 Backlight unit 14 Housing 16 Wavelength conversion member 18 Light source 26 Wavelength conversion layer 28 Substrate 32 Binder 34 Micro-particles 36 Matrix 38 Pyromethene derivative

Claims

1. It has a wavelength conversion layer and a substrate, The wavelength conversion layer contains a binder and microparticles, and The microparticles contain a pyrometene derivative and a matrix with an SP value of 9.0 (cal / cm³) or 0.5 or higher, and A wavelength conversion member in which the difference in SP values ​​between the binder and the matrix is ​​12.5 (cal / cm³) or more.

2. The oxygen permeability coefficient of the aforementioned binder is 0.01 (cc·mm) / (m ２ The wavelength conversion member according to claim 1, wherein the wavelength is less than or equal to (day atm).

3. The wavelength conversion member according to claim 1 or 2, wherein the wavelength conversion layer contains 0.01 to 5% by mass of an emulsifier.

4. The wavelength conversion member according to any one of claims 1 to 3, wherein the average particle diameter of the microparticles is 1 μm or more and 15 μm or less.

5. The wavelength conversion layer is Microparticles 34G containing a pyrometene derivative that exhibits emission observed in the region of 500 nm to 580 nm with a peak wavelength when excitation light is used, and Microparticles 34R containing a pyrometene derivative that exhibits emission observed in the region of peak wavelength between 580 nm and 750 nm when excitation light is used. A wavelength conversion member according to any one of claims 1 to 4, comprising the above.

6. The wavelength conversion member according to claim 5, wherein the wavelength conversion member includes a laminate 26Y of a wavelength conversion layer 26G containing the microparticles 34G and a wavelength conversion layer 26R containing the microparticles 34R.

7. The wavelength conversion member according to claim 5, wherein the wavelength conversion layer has a layer containing the microparticle 34G and the microparticle 34R in the same layer.

8. A composition containing microparticles 34G containing a pyrometene derivative that exhibits emission observed in the region of 500 nm to 580 nm when excitation light is used is applied to a substrate to form a wavelength conversion layer 26G. Furthermore, the laminate 26Y is formed by coating the wavelength conversion layer 26G with a composition containing microparticles 34R containing a pyrometene derivative that exhibits emission observed in the region of 580 nm to 750 nm when excitation light is used, thereby forming the wavelength conversion layer 26R. The SP value of the matrix contained in the aforementioned microparticle 34G is 9.0 (cal / cm³) or 0.5 or higher. The difference in SP values ​​between the binder contained in the wavelength conversion layer 26G and the matrix contained in the microparticles 34G is 12.5 (cal / cm³) or more. The SP value of the matrix contained in the aforementioned microparticle 34R is 9.0 (cal / cm³) or 0.5 or higher, and A method for manufacturing a wavelength conversion member, wherein the difference in SP values ​​between the binder contained in the wavelength conversion layer 26R and the matrix contained in the microparticles 34R is 12.5 (cal / cm³) or more.

9. A light-emitting device comprising a wavelength conversion member according to any one of claims 1 to 7 and a light source.

10. The light-emitting device according to claim 9, wherein the light source is selected from the group consisting of blue light-emitting diodes and ultraviolet light-emitting diodes.

11. A liquid crystal display device having a light-emitting device according to claim 9 or 10 and a liquid crystal cell.

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