JP6877101B2 - Method for manufacturing light wavelength conversion particles, light wavelength conversion particles, composition containing light wavelength conversion particles, light wavelength conversion member, light wavelength conversion sheet, backlight device, and image display device. - Google Patents

Description

The present invention relates to a method for producing light wavelength conversion particles, a light wavelength conversion particle, a light wavelength conversion particle-containing composition, a light wavelength conversion member, a light wavelength conversion sheet, a backlight device, and an image display device.

A transmissive image display device such as a liquid crystal display device is generally arranged on the back side of a transmissive image display panel such as a liquid crystal display panel, and includes a backlight device that illuminates the transmissive image display panel.

At present, in order to improve color reproducibility, it is being studied to incorporate an optical wavelength conversion member containing quantum dots into an image display device (see, for example, Patent Document 1). Quantum dots can absorb light (primary light) and emit light of different wavelengths (secondary light). The wavelength of light emitted by a quantum dot mainly depends on the particle size of the quantum dot. Therefore, in an image display device incorporating an optical wavelength conversion member, various colors can be reproduced while using a light source that projects light in a single wavelength range. For example, when a light source that emits blue light is used, the light wavelength conversion member can absorb the blue light and emit green light and red light. An image display device incorporating such an optical wavelength conversion member has excellent color purity and therefore has excellent color reproducibility.

In the light wavelength conversion member, the quantum dots are deteriorated by moisture and oxygen, and the luminous efficiency may be lowered. Therefore, in an optical wavelength conversion sheet which is a form of an optical wavelength conversion member and includes an optical wavelength conversion layer containing quantum dots, barriers for suppressing the transmission of water and oxygen on both sides of the optical wavelength conversion layer A film is provided. Since the barrier film is provided so as to sandwich the light wavelength conversion layer, the conventional light wavelength conversion sheet has a structure in which the barrier film, the light wavelength conversion layer, and the barrier film are laminated in this order.

Japanese Unexamined Patent Publication No. 2015-11518

However, a heat resistance test in which a light wavelength conversion sheet having a structure in which barrier films are provided on both sides of the light wavelength conversion layer is left in an environment of 80 ° C. for 500 hours and a heat resistance test in which the light wavelength conversion layer is left in an environment of 60 ° C. and a relative humidity of 90% for 500 hours. When the moisture and heat resistance test is performed, there is a problem that the quantum dots deteriorate and the brightness decreases, especially at the peripheral edge of the optical wavelength conversion sheet or the punctate defects such as pinholes and cracks in the barrier film. is there.

For this reason, at present, instead of the barrier film, or together with the barrier film, quantum dots are used by using optical wavelength conversion particles in which quantum dots are encapsulated in resin particles containing a compound capable of improving heat resistance and moisture heat resistance. It is being studied to suppress the deterioration of. However, if the average particle size of the light wavelength conversion particles is large and the particle size of the light wavelength conversion particles varies, the dispersibility of the light wavelength conversion particles in the composition containing the light wavelength conversion particles deteriorates, and the light wavelength Brightness unevenness may occur in the plane of the light wavelength conversion member which is a cured product of the conversion particle-containing composition.

The present invention has been made to solve the above problems. That is, a method for producing light wavelength-converted particles capable of obtaining light wavelength-converted particles having excellent heat resistance and moisture heat resistance, a small average particle size, and a small variation in particle size, excellent heat resistance and moisture resistance. Optical wavelength conversion particles having thermal properties and good dispersibility, light wavelength conversion particle-containing compositions containing such light wavelength conversion particles, and light wavelengths including cured products of such light wavelength conversion particle-containing compositions. It is an object of the present invention to provide a conversion member, a light wavelength conversion sheet, a backlight device, and an image display device.

As a result of diligent research on the above-mentioned problems, the present inventors have obtained light by suspension polymerization using a solution containing a suspension stabilizer and having a viscosity of 0.02 Pa · s or more and 10 Pa · s or less. When the wavelength conversion particles are formed, light wavelength conversion particles having a small average particle size and a small variation in particle size can be obtained, and when the obtained light wavelength conversion particles are contained in the light wavelength conversion particle-containing composition. It was found that the dispersibility of the light wavelength conversion particles was also improved. Further, when the light wavelength conversion particles are formed by using at least one of one or more elements selected from the group consisting of a sulfur-containing compound, a phosphorus-containing compound, and a nitrogen-containing compound and a carboxylic acid, excellent heat resistance and moisture heat resistance are obtained. It has been found that light wavelength conversion particles having the above can be obtained. The present invention has been completed based on such findings.

According to one aspect of the present invention, it is a method for producing light wavelength conversion particles containing light-transmitting resin particles and quantum dots contained in the resin particles, which contains a suspension stabilizer and contains a suspension stabilizer. It is selected from the group consisting of a solution having a viscosity at 25 ° C. of 0.02 Pa · s or more and 10 Pa · s or less, quantum dots, a polymerizable compound, a sulfur-containing compound, a phosphorus-containing compound, a nitrogen-containing compound, and a carboxylic acid. Provided is a method for producing light wavelength conversion particles, which comprises a step of mixing one or more compounds and a mixture containing a polymerization initiator to carry out suspension polymerization.

According to another aspect of the invention, the light wavelength-converting particles are light wavelength-converting particles comprising at least one of one or more elements and carboxylic acids selected from the group consisting of sulfur, phosphorus, and nitrogen. The light-transmitting resin particles and the quantum dots contained in the resin particles are included, the average particle diameter of the light wavelength-converted particles is 10 μm or less, and the standard deviation of the particle size distribution of the light-wavelength-converted particles is , 8 μm or less, provided are light wavelength conversion particles.

According to another aspect of the present invention, a light wavelength conversion particle-containing composition containing the above light wavelength conversion particles is provided.

According to another aspect of the present invention, there is provided a light wavelength conversion member including a cured product of the above light wavelength conversion particle-containing composition.

According to another aspect of the present invention, there is provided a light wavelength conversion sheet including a light wavelength conversion layer made of a cured product of the above light wavelength conversion particle-containing composition.

According to another aspect of the present invention, there is provided a backlight device including the light source and the light wavelength conversion member or the light wavelength conversion sheet that receives light from the light source.

According to another aspect of the present invention, there is provided an image display device including the above-mentioned light wavelength conversion member, the above-mentioned light wavelength conversion sheet, or the above-mentioned backlight device.

According to one aspect of the present invention, it is possible to obtain light wavelength conversion particles having excellent heat resistance and moisture heat resistance, a small average particle size, and a small variation in particle size. Further, according to another aspect of the present invention, a light wavelength conversion particle having excellent heat resistance and moisture heat resistance and also having good dispersibility, and a light wavelength conversion particle-containing composition containing such a light wavelength conversion particle. , A light wavelength conversion member containing a cured product of such a light wavelength conversion particle-containing composition, a light wavelength conversion sheet, a backlight device, and an image display device can be provided.

It is a schematic block diagram of the light wavelength conversion particle which concerns on embodiment. It is a schematic block diagram of other light wavelength conversion particles which concerns on embodiment. It is a schematic block diagram of the light wavelength conversion sheet which concerns on embodiment. It is a figure which shows the operation of the light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. FIG. 5 is a cross-sectional view taken along the line I-I of the optical wavelength conversion sheet of FIG. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the image display device including the backlight device which concerns on embodiment. It is a perspective view of the lens sheet shown in FIG. It is sectional drawing along the line II-II of the lens sheet of FIG. It is a schematic block diagram of another backlight apparatus which concerns on embodiment. It is a schematic block diagram of the light source shown in FIG. It is a schematic block diagram of another backlight apparatus which concerns on embodiment. FIG. 16 is an enlarged view of the vicinity of the light entering surface of the optical plate shown in FIG.

Hereinafter, a method for producing light wavelength conversion particles, a composition containing light wavelength conversion, a light wavelength conversion member, a light wavelength conversion sheet, a backlight device, and an image display device according to an embodiment of the present invention will be described with reference to the drawings. To do. In the present specification, terms such as "sheet" and "film" are not distinguished from each other based only on the difference in designation. Therefore, for example, "sheet" is used to include a member that can also be called a film, and "film" is used to include a member that can also be called a sheet. FIG. 1 is a schematic configuration diagram of a light wavelength conversion particle according to the present embodiment, FIG. 2 is a schematic configuration diagram of another light wavelength conversion particle according to the present embodiment, and FIG. 3 is a schematic configuration diagram of another light wavelength conversion particle according to the present embodiment. FIG. 4 is a schematic configuration diagram of a conversion sheet, FIG. 4 is a diagram showing the operation of the light wavelength conversion sheet according to the present embodiment, and FIGS. 5 to 7, 9, and 10 are other light wavelengths according to the present embodiment. It is a schematic block diagram of the conversion sheet, and FIG. 8 is a cross-sectional view of the optical wavelength conversion sheet of FIG. 7 along the line I-I.

<<< Manufacturing method of light wavelength conversion particles >>>
The light wavelength conversion particles are particles that convert the wavelength of incident light into another wavelength, and include light-transmitting resin particles and quantum dots contained in the resin particles. The method for producing light wavelength conversion particles according to the present embodiment comprises a solution containing a suspension stabilizer and having a viscosity at 25 ° C. of 0.02 Pa · s or more and 10 Pa · s or less, quantum dots, a polymerizable compound, and the like. A mixture containing one or more compounds selected from the group consisting of sulfur-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds, and carboxylic acids and a polymerization initiator (hereinafter, this mixture is referred to as "mixture for light wavelength conversion particles". It includes a step of performing suspension polymerization by mixing with (referred to as). Prior to suspension polymerization, it is preferable to first prepare the above solution and the above mixture.

<< Solution >>
The solution contains a suspension stabilizer and has a viscosity at 25 ° C. of 0.02 Pa · s or more and 10 Pa · s or less. The solution may contain a suspension aid in combination with a suspension stabilizer. In addition, the solution may contain water-soluble inorganic salts such as sodium chloride, sodium sulfate, and aluminum sulfate in order to suppress polymerization in the aqueous phase.

The viscosity of the solution at 25 ° C. is 0.02 Pa · s or more and 10 Pa · s or less. However, by setting the viscosity of the solution at 25 ° C. to 0.02 Pa · s or more, the shear stress during stirring can be increased. Light wavelength conversion particles can be obtained by evenly adding to the mixture for light wavelength conversion particles and having a small variation in particle size, and by setting the viscosity of the solution at 25 ° C. to 10 Pa · s or less, the entire solution becomes uniform. Can be agitated. The viscosity of the solution is the average value of the viscosities measured 10 times using a B-type viscometer (product name "TVB-10", manufactured by Toki Sangyo Co., Ltd.) at 25 ° C. The lower limit of the viscosity of the solution at 25 ° C. is preferably 0.025 Pa · s or more, and the upper limit is preferably 8 Pa · s or less.

In order to make the solution have a viscosity in the above range, for example, the type and concentration of the suspension stabilizer may be adjusted, or a thickener may be added to the solution. The concentration of the suspension stabilizer in the solution is preferably 0.05% by mass or more and 80% by mass or less from the viewpoint of keeping the viscosity of the solution in the above range. The concentration of the suspension stabilizer in the solution can be calculated by evaporating the solvent by heating the solution and weighing the remaining dried suspension stabilizer. The lower limit of the concentration of the suspension stabilizer in the solvent of the above solution is more preferably 0.1% by mass or more, and the upper limit is more preferably 70% by mass or less.

The above solution may be obtained by adding a suspension stabilizer to the solvent, or may be obtained by preparing a solution containing the suspension stabilizer in advance and adding this solution to the solvent.

<Solvent>
As the solvent of the solution, for example, a poor solvent in which the mixture for light wavelength conversion particles described later is hardly dissolved is preferable. Among the poor solvents, water is particularly preferable.

<Suspension stabilizer>
Examples of the suspension stabilizer include water-soluble polymers such as nonionic water-soluble polymers. Examples of the nonionic water-soluble polymer include polyalkylene oxides such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, polyvinyl pyrrolidone, hydroxypropyl methyl cellulose, and polyethylene oxide, and polyoxyethylene-polyoxypropylene block copolymers. , Polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene nonylphenyl ether, polyethylene glycol fatty acid ester, polyoxyethylene laurylamine and the like. Among these, polyvinyl alcohol, polyvinylpyrrolidone, and polyoxyethylene-polyoxypropylene copolymer are preferable, and polyvinyl alcohol is most preferable.

Examples of polyvinyl alcohol include Gosenol NH-18, N-300, NL-05, C-500, P-610, GH-23, KH-20 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), POVAL3-98, 5- 98, 11-98, 28-98, 60-98, 27-95, 22-88, 32-80 (manufactured by Kuraray Co., Ltd.) and the like can be mentioned. Polyvinyl alcohol used as a suspension stabilizer usually has a saponification degree of about 70 mol% or more and 99 mol% or less.

<Suspension aid>
The suspension aid is a substance also known as a dispersion aid, and is, for example, an anionic surfactant such as sodium dodecylbenzene sulfonate, sodium lauryl sulfate, sodium alkylnaphthalene sulfonate, sodium dialkylsulfosuccinate and the like. Examples thereof include low molecular weight surfactants, water-soluble inorganic salts such as boric acid, sodium carbonate, disodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium sulfate. As the suspension aid, disodium hydrogen phosphate is preferable. The suspension aid may be present in the solution from the beginning of the polymerization because it is less likely to cause deterioration of transparency and yellowing problems during the molding process.

<< Mixture for light wavelength conversion particles >>
The mixture for light wavelength conversion particles is one or more compounds selected from the group consisting of quantum dots, polymerizable compounds, sulfur-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds, and carboxylic acids (hereinafter, this compound). Is referred to as a "specific compound") and a polymerization initiator.

When preparing the mixture for light wavelength conversion particles, the quantum dots, the polymerizable compound, and the polymerization initiator may be charged into a container such as a disposable cup, and then the specific compound may be charged.

<Quantum dot>
Quantum dots are nano-sized semiconductor particles that have a quantum confinement effect. The particle size and average particle size of the quantum dots are, for example, 1 nm or more and 20 nm or less. When a quantum dot absorbs light from an excitation source and reaches an energy excited state, it emits energy corresponding to the energy band gap of the quantum dot. Therefore, by adjusting the particle size of the quantum dots or the composition of the substance, the energy band gap can be adjusted, and energy in various levels of wavelength bands can be obtained. In particular, quantum dots can generate strong fluorescence in a narrow wavelength band.

Specifically, the energy band gap of quantum dots increases as the particle size decreases. That is, as the crystal size becomes smaller, the emission of the quantum dots shifts to the blue side, that is, to the high energy side. Therefore, by changing the particle size of the quantum dots, the emission wavelength can be adjusted over the entire wavelength of the spectrum in the ultraviolet region, the visible region, and the infrared region. For example, when the quantum dot is composed of CdSe / ZnS described later, when the particle diameter of the quantum dot is 2.0 nm or more and 4.0 nm or less, blue light is emitted and the particle diameter of the quantum dot is 3.0 nm. When it is 6.0 nm or less, it emits green light, and when the particle size of the quantum dots is 4.5 nm or more and 10.0 nm or less, it emits red light. In the above, the range of the particle size of the quantum dot that emits blue light and the particle size of the quantum dot that emits green light partially overlaps, and the particle size of the quantum dot that emits green light and the red light are used. The range of the particle size of the emitted quantum dots overlaps in part, but even if the quantum dots have the same particle size, the emission color may differ depending on the size of the core of the quantum dots, so there is no contradiction. It's not something to do. In the present specification, "blue light" is light having a wavelength range of 380 nm or more and less than 480 nm, "green light" is light having a wavelength range of 480 nm or more and less than 590 nm, and "red light" is Light having a wavelength range of 590 nm or more and 750 nm or less.

As the quantum dots, one type of quantum dots may be used, but it is also possible to use two or more types of quantum dots, each of which has an emission band in a single wavelength range, depending on the particle size or material. ..

Quantum dots can generate strong fluorescence in a desired narrow wavelength range. Therefore, the backlight device using the light wavelength conversion sheet can illuminate the display panel with the light of the three primary colors having excellent color purity. In this case, the display panel will have excellent color reproducibility.

Quantum dots are composed of, for example, a core made of a first semiconductor compound, a shell made of a second semiconductor compound covering the core and different from the first semiconductor compound, and a ligand bonded to the surface of the shell. Has been done.

Examples of the first semiconductor compound constituting the core include MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, II-VI semiconductor compounds such as HgS, HgSe and HgTe, III such as AlN, AlP, AlAs, AlSb, GaAs, GaP, GaN, GaSb, InN, InAs, InP, InSb, TiN, TiP, TiAs and TiSb Examples thereof include semiconductor compounds such as -V semiconductor compounds, IV semiconductors such as Si, Ge and Pb, or semiconductor crystals containing semiconductors. Further, a semiconductor crystal containing a semiconductor compound containing three or more elements such as InGaP can also be used. Among these, semiconductor crystals such as CdS, CdSe, CdTe, InP, and InGaP are preferable from the viewpoints of ease of fabrication, controllability of particle size capable of obtaining light emission in the visible range, and the like.

As the second semiconductor compound constituting the shell, it is preferable to use a semiconductor compound having a bandgap higher than that of the first semiconductor compound constituting the core so that excitons are confined in the core. As a result, the luminous efficiency of the quantum dots can be increased. Examples of the second semiconductor compound constituting the shell include ZnS, ZnSe, CdS, GaN, CdSSe, ZnSeTe, AlP, ZnSTe, ZnSSe and the like.

Specific combinations of the core-shell structure (core / shell) composed of the core and the shell include, for example, CdSe / ZnS, CdSe / ZnSe, CdSe / CdS, CdTe / CdS, InP / ZnS, Gap / ZnS, Si / ZnS, and the like. InN / GaN, InP / CdSSe, InP / ZnSeTe, InGaP / ZnSe, InGaP / ZnS, Si / AlP, InP / ZnSTe, InP / ZnSSe, InGaP / ZnSTe, InGaP / ZnSSe and the like can be mentioned.

The ligand is for stabilizing unstable quantum dots. Examples of the ligand include sulfur-containing compounds such as thiol, phosphorus-containing compounds such as phosphine-based compounds or phosphine oxides, nitrogen-containing compounds such as amines, and carboxyl group-containing compounds.

The shape of the quantum dot is not particularly limited, and may be, for example, spherical, rod-shaped, disk-shaped, or other shape. When the shape of the quantum dot is not spherical, the particle size of the quantum dot can be a true spherical value having the same volume.

Information such as the particle size, average particle size, shape, and dispersion state of the quantum dots can be obtained by a transmission electron microscope or a scanning transmission electron microscope. Further, since the emission color of the quantum dot changes depending on the particle size, it is possible to obtain the particle size of the quantum dot by confirming the emission color of the quantum dot. Further, the crystal structure and crystallite size of the quantum dots can be known by X-ray crystal diffraction (XRD). Furthermore, information on the particle size of quantum dots and the like can be obtained from the ultraviolet-visible (UV-Vis) absorption spectrum.

The content of the quantum dots in the mixture for light wavelength conversion particles is preferably 0.01% by mass or more and 2% by mass or less with respect to the total mass of the polymerizable compound and the specific compound. By setting the quantum dot content to 0.01% by mass or more with respect to the total mass of the polymerizable compound and the specific compound, sufficient emission intensity can be obtained, and the quantum dot content can be set to the polymerizable compound. By setting the total mass of the specific compound to 2% by mass or less, a sufficient transmitted light intensity of the excitation light can be obtained.

<Polymerizable compound>
The polymerizable compound (curable compound) is a polymerizable compound, and examples thereof include a radical polymerizable compound and a cationically polymerizable compound.

(Radical polymerizable compound)
A radically polymerizable compound has at least one radically polymerizable functional group in the molecule. Examples of the radically polymerizable functional group include ethylenically unsaturated groups such as (meth) acryloyl group, vinyl group and allyl group. The "(meth) acryloyl group" means that both "acryloyl group" and "methacryloyl group" are included.

Examples of the radically polymerizable compound include a radically polymerizable monomer, a radically polymerizable oligomer, and a radically polymerizable prepolymer, which can be appropriately adjusted and used.

Examples of the radically polymerizable monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ethylene glycol di (meth) acrylate, and diethylene glycol di (meth) acrylate. Triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, trimethyl propantri (meth) acrylate, trimethylol ethanetri (meth) acrylate, pentaerythritol di (meth) ) Acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, glycerol (meth) acrylate, tricyclodecanedimethanol di ( Examples thereof include meta) acrylate, polyester acrylate, and ω-carboxy-polycaprolactone mono (meth) acrylate.

As the radically polymerizable oligomer, a polyfunctional oligomer having two or more functionalities is preferable, and a polyfunctional oligomer having three or more radical polymerizable functional groups (trifunctional) is more preferable. Examples of the polyfunctional oligomer include polyester (meth) acrylate, urethane (meth) acrylate, polyester-urethane (meth) acrylate, polyether (meth) acrylate, polyol (meth) acrylate, melamine (meth) acrylate, and isocyanurate. Examples thereof include (meth) acrylate and epoxy (meth) acrylate.

The radically polymerizable prepolymer has a weight average molecular weight of more than 10,000, and the weight average molecular weight is preferably 10,000 or more and 80,000 or less, and more preferably 10,000 or more and 40,000 or less. When the weight average molecular weight is 80,000 or less, the deterioration of the coating suitability can be suppressed, so that the deterioration of the appearance of the obtained light wavelength conversion member can be suppressed. When a radical-polymerizable prepolymer having a weight average molecular weight of more than 80,000 is used, it is preferable to use the radical-polymerizable monomer and the radical-polymerizable oligomer in combination. Examples of the polyfunctional radically polymerizable prepolymer include urethane (meth) acrylate, isocyanurate (meth) acrylate, polyester-urethane (meth) acrylate, and epoxy (meth) acrylate.

(Cation-polymerizable compound)
A cationically polymerizable compound has at least one cationically polymerizable functional group in the molecule. Examples of the cationically polymerizable functional group include a cyclic ether group such as an epoxy group and an oxetanyl group, a vinyl ether group and the like.

An epoxy compound is a compound having one or more epoxy groups in the molecule. The epoxy compound is not particularly limited, but for example, bisphenol A type epoxy compound, bisphenol F type epoxy compound, bisphenol S type epoxy compound, biphenyl type epoxy compound, fluorene type epoxy compound, novolak phenol type epoxy compound, cresol novolac type epoxy. Aromatic compounds such as compounds and modified products thereof, or alkylene glycol diglycidyl ethers such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether or 1,6-hexanediol diglycidyl ether, glycerin or an alkylene oxide adduct thereof. Diglycidyl ether of polyhydric alcohol such as di or triglycidyl ether, diglycidyl ether of polyethylene glycol or its alkylene oxide adduct, polyalkylene glycol diglycidyl ether such as diglycidyl ether of polypropylene glycol or its alkylene oxide adduct, And aliphatic systems such as alkylene oxide. Here, examples of the alkylene oxide include aliphatic epoxy compounds such as ethylene oxide and propylene oxide, 3', 4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, and 3,4-epoxycyclohexylmethyl methacrylate. Examples thereof include an alicyclic epoxy compound containing one or more epoxy groups and one or more ester groups in the molecule.

<Specific compound>
The specific compound is one or more compounds selected from the group consisting of a sulfur-containing compound, a phosphorus-containing compound, a nitrogen-containing compound, and a carboxylic acid, and is a compound for suppressing deterioration of quantum dots.

The content of the specific compound in the mixture for light wavelength conversion particles is preferably 5% by mass or more and 80% by mass or less with respect to the mass of the polymerizable compound. By setting the content of the specific compound to 5% by mass or more with respect to the mass of the polymerizable compound, deterioration of the quantum dots can be further suppressed, and the content of the specific compound is 80 with respect to the mass of the polymerizable compound. By making the mass% or less, sufficient curing can be performed at the time of forming the light wavelength conversion particles. The lower limit of the content of the specific compound in the mixture for light wavelength conversion particles is more preferably 20% by mass or more, and the upper limit is more preferably 60% by mass or less.

(Sulfur-containing compound)
The sulfur-containing compound is a compound containing sulfur. The sulfur-containing compound is not particularly limited, and examples thereof include a thiol compound, a thioether compound, a disulfide compound, and a thiophene compound. When a thiol compound is used as the sulfur compound, it is preferable that the thiol compound and the polymerizable compound form a copolymer by a thiol-ene reaction in the resin particles. By copolymerizing the thiol compound and the polymerizable compound, the thiol compound can be fixed in the resin particles. When a thiol compound is used, it is preferable to use a primary thiol compound from the viewpoint of excellent curability by ionizing radiation or heat, but from the viewpoint of pot life at the time of coating and suppression of odor, secondary thiol is used. It is preferable to use a compound or a tertiary thiol compound.

The primary thiol compound refers to a compound in which one hydrocarbon group is bonded to carbon to which a thiol group is bonded. The secondary thiol compound is a compound in which two hydrocarbon groups are bonded to carbon to which a thiol group is bonded. The tertiary thiol compound refers to a compound in which three hydrocarbon groups are bonded to carbon to which a thiol group is bonded. The thiol compound may have one or more thiol groups in one molecule, but is preferably two or more from the viewpoint of improving the heat resistance and moisture heat resistance of the quantum dots.

式中、Ｒ^１は水素原子、置換されていてもよい炭素原子数１〜１０のアルキル基であり、Ｒ^２は置換されていてもよい炭素原子数１〜１０のアルキレン基であり、Ｒ^３は炭素原子以外の原子を含んでいてもよい炭素原子数１〜１５のｎ価の脂肪族基であり、ｍは１〜２０の整数であり、ｎは１〜３０の整数である。 The thiol compound is not particularly limited, but the compound represented by the following general formula (1) is preferable from the viewpoint of curability at the time of forming the light wavelength conversion layer and improvement of heat resistance and moisture heat resistance of the quantum dots.

In the formula, R ¹ is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may be ^{substituted, and R 2} is an alkylene group having 1 to 10 carbon atoms which may be substituted, and R ³ Is an n-valent aliphatic group having 1 to 15 carbon atoms which may contain atoms other than carbon atoms, m is an integer of 1 to 20, and n is an integer of 1 to 30.

The alkyl group of R ¹ may be linear or branched. Examples of the alkyl group of R ¹ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, n-pentyl group and neopentyl group. tert-pentyl group, isopentyl group, 2-methylbutyl group, 1-ethylpropyl group, hexyl group, isohexyl group, 4-methylpentyl group, 3-methylpentyl group, 2-methylpentyl group, 1-methylpentyl group, 3 , 3-dimethylbutyl group, 2,2-dimethylbutyl group, 1,1-dimethylbutyl group, 1,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,3-dimethylbutyl group, 1-ethylbutyl Examples thereof include a group, a 2-ethylbutyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group.

The alkylene group of R ² may be either linear or branched. Examples ^{of the alkylene group of R 2} include a methylene group, an ethylene group, a trimethylene group, a propylene group, an isopropylene group and the like.

When the alkyl group of ^{R 1 or the alkylene group of R 2} is substituted, the substituent includes a halogen atom, a hydroxyl group, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, a carboxyl group, a phenyl group and the like. The groups to be selected are listed. Halogen atoms include fluorine atoms, chlorine atoms, and bromine atoms.

One methylene group in the alkyl group of R ^{1 or the alkylene group of R 2} or two or more non-adjacent methylene groups are -O-, -S-, -SO _2- , -CO-, -COO-,-. ^{OCO -, - NR 4 -,} - CONR 4 -, - NR 4 CO -, - N = CH- and -CH = CH- may be substituted with at least one group selected from the group consisting of (formula Among them, R ⁴ independently represents hydrogen or an alkyl group having 1 to 5 carbon atoms.)

Examples of atoms other than carbon atoms that may be contained in the aliphatic group of R ^{3 include nitrogen atoms, oxygen atoms, sulfur atoms and the like.}

Of these, an alkyl group having 1 to 5 carbon atoms in which ^{R 1} may be substituted is an alkyl group from the viewpoint of curability during formation of light wavelength conversion particles and improvement of heat resistance and moist heat resistance of quantum dots. R ² is an alkylene group having 1 to 5 carbon atoms which may be substituted, R ³ is an aliphatic group having 1 to 10 carbon atoms, m is 1 to 10, and n is 1 to 15. A primary thiol compound or a secondary thiol compound is preferable. One methylene group in the alkylene group of R ² or two or more non-adjacent methylene groups may be substituted with the same group as described above.

Specific examples of the primary thiol compound include hexanedithiol, decandithiol, ethylene glycol bisthioglycolate, 1,4-butanediol bisthioglycolate, trimethylolpropanetristhioglycolate, pentaerythritol tetraxthioglycolate, and ethylene. Glycerol bis (3-mercaptopropionate), 1,2-propylene glycol bis (3-mercaptopropionate), 1,3-propylene glycol bis (3-mercaptopropionate), 1,4-butanediol bis (3-Mercaptopropionate), Glycerintris (3-Mercaptopropionate), Trimethylol Propylene Trise (3-Mercaptopropionate), Trimethylol Etantris (3-Mercaptopropionate), Pentaerythritol Tetrakiss (3-Mercaptopropionate) 3-Mercaptopropionate), dipentaerythritol hexakis (3-mercaptopropionate) and the like.

Specific examples of the secondary thiol compound include 1,4-bis (3-mercaptobutylyloxy) butane and 1,3,5-tris (3-mercaptobutyloxyethyl) -1,3,5-triazine-2. , 4, 6 (1H, 3H, 5H) -trione, pentaerythritol tetrakis (3-mercaptobutyrate), trimethylolpropane tris (3-mercaptobutyrate), trimethylolethane ethanetris (3-mercaptobutyrate), etc. Can be mentioned. Specific examples of the tertiary thiol compound include tert-butyl mercaptan and the like.

式中、ｑは０または１の整数であり、Ｒ^５〜Ｒ^７は、それぞれ独立して、水素、水酸基、置換されていてもよい炭素原子数１〜３０の直鎖または分岐のアルキル基、置換されていてもよい炭素数１〜３０の直鎖または分岐のアルコキシ基、置換されていてもよい炭素数１〜３０の直鎖または分岐のアルケニル基、置換されていてもよい炭素数１〜３０の直鎖または分岐のアルキニル基、置換されていてもよい炭素数３〜６のシクロアルキル基、置換されていてもよいフェニル基、置換されていてもよいビフェニル基、置換されていてもよいナフチル基、置換されていてもよいフェノキシ基、または置換されていてもよい複素環基、または水酸基を表す。 (Phosphorus-containing compound)
The phosphorus-containing compound is a compound containing phosphorus. The phosphorus-containing compound is not particularly limited, and examples thereof include a phosphonic acid-based compound, a phosphinic acid-based compound, a phosphine oxide-based compound, a phosphonic acid-based compound, a phosphinic acid-based compound, and a phosphine-based compound. Among these, the compound represented by the following general formula (2) is preferable from the viewpoint of improving the curability at the time of forming the light wavelength conversion particles and the heat resistance and moisture heat resistance of the quantum dots.

In the formula, q is an integer of 0 or 1, and R ^{5 to} R ⁷ are independently hydrogen, hydroxyl groups, and linear or branched alkyl groups having 1 to 30 carbon atoms which may be substituted. A linear or branched alkoxy group having 1 to 30 carbon atoms which may be substituted, a linear or branched alkenyl group having 1 to 30 carbon atoms which may be substituted, and a linear or branched alkenyl group having 1 to 30 carbon atoms which may be substituted. 30 linear or branched alkynyl groups, optionally substituted cycloalkyl groups having 3 to 6 carbon atoms, optionally substituted phenyl groups, optionally substituted biphenyl groups, optionally substituted Represents a naphthyl group, an optionally substituted phenoxy group, or an optionally substituted heterocyclic group, or a hydroxyl group.

When ^{any of R 5 to} R ⁷ has a substituent, the substituent includes a halogen atom (F, Cl, Br), an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. , An alkenyl group having 1 to 6 carbon atoms, an alkynyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, a (meth) acryloyl group, a (meth) acryloyloxy group, an amino group, a hydroxyl group, a carboxyl group, Examples thereof include an alkylamino group having 1 to 6 carbon atoms, a nitro group, a phenyl group, a biphenyl group, a naphthyl group, a phenoxy group, a heterocyclic group and the like.

Heterocyclic groups include pyridyl group, pyrimidinyl group, pyridadyl group, pyrazole group, frill group, thienyl group, oxazolyl group, isoxazolyl group, oxadiazolyl group, thiazolyl group, isothiazolyl group, imidazolyl group, triazolyl group, pyrrole group and pyrazolyl group. , Or a tetrazolyl group.

Specific examples of the phosphorus compound include tris (2-ethylhexyl) phosphine, trilaurylphosphine, tris (tridecylic) phosphine, bis (decyl) pentaerythritol diphosphite, and bis (tridecylic) pentaerythritol diphosphite. , Triphenylphosphine, trisnonylphenylphosphine, butyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, 2-hydroxyethyl methacrylate acid phosphate, dibutyl phosphate, dimethyl vinyl phosphate, di-2-ethylhexyl hydrozen phosphate , Georail Hydrozenphosphite and the like.

(Nitrogen-containing compound)
The nitrogen-containing compound is a compound containing nitrogen. The nitrogen-containing compound is not particularly limited, but an amine compound is preferable from the viewpoint of curability at the time of forming light wavelength conversion particles and improvement of heat resistance and moisture heat resistance of quantum dots. The amine compound may be any of a primary amine compound, a secondary amine compound, a tertiary amine compound, and a diamine compound.

Specific examples of the amine compound include laurylamine, myristylamine, cetylamine, stearylamine, oleylamine, behenylamine, distearylamine, dimethyllaurylamine, dimethylmyristylamine, dimethylstearylamine, dilaurylmonomethylamine, and trioctylamine. , Oleyl propylene diamine and the like.

(carboxylic acid)
Carboxylic acid is a compound containing at least one carboxyl group. The carboxylic acid may contain two or more carboxyl groups, or may contain a polymerizable functional group.

The weight average molecular weight of the carboxylic acid is preferably 150 or more and 50,000 or less from the viewpoint of being difficult to volatility, having excellent dispersibility, and being easy to work with. In the present specification, the "weight average molecular weight" is a value obtained by dissolving in a solvent such as tetrahydrofuran (THF) and converting into polystyrene by a conventionally known gel permeation chromatography (GPC) method. The lower limit of the weight average molecular weight of the carboxylic acid is more preferably 300 or more, and the upper limit is more preferably 10,000 or less.

The carboxyl group equivalent (weight average molecular weight / number of carboxyl groups) of the carboxylic acid is preferably 150 or more and 50,000 or less from the viewpoint of facilitating the presence of the carboxylic acid around the quantum dots. The lower limit of the carboxyl group equivalent of the carboxylic acid is more preferably 300 or more, and the upper limit is more preferably 10,000 or less.

Specific examples of the above carboxylic acid include ω-carboxy-polycaprolactone mono (meth) acrylate, monohydroxyethyl phthalate (meth) acrylate, 2-acryloyloxyethyl succinic acid, a reaction product of pentaerythritol and acrylic acid, and succinate anhydride. Acid reactants include 3-buteneic acid, 10-undecenoic acid, n-octanoic acid, stearic acid, adipic acid, dodecanoic acid, 4,4'-dicarboxydiphenyl ether, octadecanoic acid and the like. Among these, ω-carboxy-polycaprolactone mono (meth) acrylate and 2-acryloyloxy from the viewpoint of fixing the carboxylic acid in the resin constituting the resin particle 2 and facilitating the presence of the carboxylic acid around the quantum dots. Ethyl succinic acid is preferred.

<Polymerization initiator>
A polymerization initiator is a component that is decomposed by light or heat to generate radicals or ionic species to initiate or proceed with the polymerization (crosslinking) of a polymerizable compound. Examples of the polymerization initiator include a radical polymerization initiator (for example, a photoradical polymerization initiator, a thermal radical polymerization initiator), a cationic polymerization initiator (photocationic polymerization initiator, a thermal cationic polymerization initiator), or a mixture thereof. Be done.

Examples of the photoradical polymerization initiator include benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanosen compounds, oxime ester compounds, benzoin ether compounds, thioxanthone and the like.

Commercially available photoradical polymerization initiators include, for example, IRGACURE184, IRGACURE369, IRGACURE379, IRGACURE651, IRGACURE819, IRGACURE907, IRGACURE2959, IRGACURE OXE01, and Lucillin TPO (all manufactured by BASF Japan). Examples thereof include ADEKA), SPEEDCURE EMK (manufactured by Siebel Hegner Japan), benzoine methyl ether, benzoin ethyl ether, and benzoin isopropyl ether (all manufactured by Tokyo Chemical Industry Co., Ltd.).

Examples of the thermal radical polymerization initiator include peroxides and azo compounds. Among these, a polymer azo initiator composed of a polymer azo compound is preferable. Examples of the polymer azo initiator include those having a structure in which a plurality of units such as polyalkylene oxide and polydimethylsiloxane are bonded via an azo group.

Examples of the polymer azo initiator having a structure in which a plurality of units such as polyalkylene oxide are bonded via the azo group include a polycondensate of 4,4'-azobis (4-cyanopentanoic acid) and polyalkylene glycol. Examples thereof include a polycondensate of 4,4'-azobis (4-cyanopentanoic acid) and polydimethylsiloxane having a terminal amino group.

Examples of the peroxide include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, peroxyesters, diacyl peroxides, peroxydicarbonates and the like.

Commercially available thermal radical polymerization initiators include, for example, Perbutyl O, Perhexyl O, Perbutyl PV (all manufactured by NOF CORPORATION), V-30, V-501, V-601, and VPE-0201. , VPE-0401, VPE-0601 (all manufactured by Wako Pure Chemical Industries, Ltd.) and the like.

Examples of the photocationic polymerization initiator include aromatic diazonium salts, aromatic iodonium salts, and aromatic sulfonium salts. Examples of commercially available photocationic polymerization initiators include ADEKA PUTMER SP-150 and ADEKA PTOMER SP-170 (both manufactured by ADEKA).

Examples of the thermal cationic polymerization initiator include various onium salts such as a quaternary ammonium salt, a phosphonium salt, and a sulfonium salt. Commercially available thermal cationic polymerization initiators include, for example, ADEKA OPTON CP-66, ADEKA OPTON CP-77 (all manufactured by ADEKA), Sun Aid SI-60L, Sun Aid SI-80L, and Sun Aid SI-100L (all of which are manufactured by ADEKA). All of them include Sanshin Kagaku Kogyo Co., Ltd.) and CI series (Nippon Soda Co., Ltd.).

The content of the polymerization initiator in the mixture for light wavelength conversion particles is preferably 0.01% by mass or more and 10.0% by mass or less with respect to the total mass of the polymerizable compound and the specific compound. By setting the content of the polymerization initiator to 0.01% by mass or more with respect to the total mass of the polymerizable compound and the specific compound, the polymerizable compound can be reliably cured, and the content of the polymerization initiator Is 10.0% by mass or less based on the total mass of the polymerizable compound and the specific compound, so that yellowing of the light wavelength conversion member can be suppressed.

<< Suspension polymerization process >>
After preparing the solution and the mixture for light wavelength conversion particles, the solution and the mixture for light wavelength conversion particles are mixed and suspension polymerization is performed. As a result, light composed of light-transmitting resin particles containing at least one of one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen and carboxylic acid, and quantum dots contained in the resin particles. Wavelength conversion particles are formed.

Disperse the mixture for light wavelength conversion particles in the solution by stirring the mixture consisting of the solution and the mixture for light wavelength conversion particles after mixing the above solution and the mixture for light wavelength conversion particles and before suspension polymerization. Is preferable. The method of dispersing the mixture for light wavelength conversion particles in the solution is not particularly limited, and examples thereof include a method of dispersing the mixture using a homogenizer.

Suspension polymerization may be carried out by irradiating ionizing radiation such as ultraviolet rays, but is preferably carried out by heating. Examples of ionizing radiation in the present specification include visible light, ultraviolet light, X-ray, electron beam, α-ray, β-ray, and γ-ray.

When suspension polymerization is carried out by heating, the temperature of the mixture (suspension) is preferably in the range of 40 ° C. or higher and 150 ° C. or lower. The polymerization initiator can be activated by setting the temperature of the mixed solution to 40 ° C. or higher, and the polymerizable compound, quantum dots, light wavelength conversion particles, etc. can be activated by setting the temperature of the mixed solution to 150 ° C. or lower. Deterioration due to heat can be suppressed. The lower limit of the temperature of the mixed solution is preferably 50 ° C. or higher, and the upper limit is preferably 100 ° C. or lower. Suspension polymerization may be carried out in an inert gas atmosphere that is inert to the mixture for light wavelength conversion particles, such as a nitrogen atmosphere.

Suspension polymerization is preferably carried out while stirring the above mixture. Stirring may be performed to such an extent that the mixture for light wavelength conversion particles can be prevented from floating as droplets and the light wavelength conversion particles generated by polymerization can be prevented from settling.

The light wavelength conversion particles obtained by suspension polymerization are separated by a method such as suction filtration, centrifugal dehydration, and centrifugation, and further, the separated light wavelength conversion particles are washed with water and dried.

In the above, the optical wavelength conversion particles composed of the resin particles and the quantum dots contained in the resin particles are obtained. However, the resin particles, the quantum dots contained in the resin particles, and the quantum dots formed in the resin particles are formed on the surface of the resin particles. When the light wavelength conversion particles composed of the coated coat layer are formed, the coat layer is formed on the surface of the resin particles after suspension polymerization.

Although it depends on the function of the coat layer, when the coat layer has a function of retaining the shape of the resin particles, the coat layer can be formed by using, for example, a composition for a coat layer containing a polymerizable compound. .. Since the polymerizable compound is the same as the polymerizable compound used for forming the resin particles, the description thereof will be omitted here. Among these, from the viewpoint of improving the adhesion between the resin particles and the coat layer, for example, when the resin particles are formed from a radically polymerizable compound, it may be formed by using a composition for a coat layer containing the radically polymerizable compound. Preferably, when the resin particles are formed of a cationically polymerizable compound, it is preferably formed by using a composition for a coat layer containing the cationically polymerizable compound.

<<< Light wavelength conversion particles >>>
The light wavelength conversion particle 1 is obtained by the above-mentioned production method, and as shown in FIG. 1, one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen (hereinafter, this element is used. It contains a resin particle 2 containing at least one of (referred to as a "specific element") and a carboxylic acid, and one or more quantum dots 3 contained in the resin particle 2. Further, the light wavelength conversion particles may be light wavelength conversion particles 5 provided with a coat layer 4 covering the surface of the resin particles 2 as shown in FIG.

In the light wavelength conversion particles 1 and 5, the content of the specific element in the light wavelength conversion particles 1 measured by fluorescent X-ray analysis (XRF) is preferably 0.5% by mass or more. By setting the content of a specific element to 0.5% by mass or more, deterioration of quantum dots can be reliably suppressed. The content of the specific element is taken as the average value obtained by measuring the content of the specific element in each of the 20 light wavelength conversion particles. The content of a specific element can be measured by using a fluorescent X-ray analyzer (product name "EDX-800HS", manufactured by Shimadzu Corporation). The lower limit of the content of the specific element in the light wavelength conversion particles 1 and 5 measured by X-ray fluorescence analysis (XRF) is more preferably 1% by mass or more, and the upper limit of the content of the specific element is. It is more preferably 20% by mass or less, and further preferably 10% by mass or less. By setting the content of the specific element to 20% by mass or less, sufficient curing can be performed at the time of forming the light wavelength conversion particles. When the light wavelength conversion particles contain two or more specific elements, the above-mentioned content means the total content of the specific elements.

The average particle size of the light wavelength conversion particles 1 and 5 is preferably 10 μm or less. By setting the average particle size of the light wavelength conversion particles 1 and 5 to 10 μm or less, the dispersibility is improved. The lower limit of the average particle size of the light wavelength conversion particles 1 and 5 is preferably 0.5 μm or more from the viewpoint of the extraction efficiency of the light wavelength conversion particles 1 and 5 and the difficulty of agglomeration of the particles. The average particle size of the light wavelength conversion particles 1 and 5 is obtained by measuring the particle size of 20 light wavelength conversion particles in the observation of the light wavelength conversion particles with a scanning electron microscope (SEM) and calculating the average value thereof. be able to.

The standard deviation of the particle size distribution of the light wavelength conversion particles 1 and 5 is preferably 8 μm or less. When the standard deviation of the particle size distribution is 8 μm or less, light wavelength conversion particles with small variation can be obtained. The standard deviation of the particle size distribution of the light wavelength-converted particles can be calculated based on the particle size distribution of the light-wavelength-converted particles measured when the average particle size is obtained.

The shapes of the light wavelength conversion particles 1 and 5 are not particularly limited, and are, for example, spherical (true spherical, substantially true spherical, elliptical spherical, etc.), polyhedral, rod-shaped (cylindrical, prismatic, etc.), flat plate, and flaky. , Indefinite shape and the like. When the shape of the light wavelength conversion particle 1 is not spherical, the particle size of the light wavelength conversion particle 1 is a true spherical particle size having the same volume.

It is preferable that each of the light wavelength conversion particles 1 and 5 contains one or more quantum dots 3. By setting the number of quantum dots contained in one light wavelength conversion particle to one or more, it is possible to suppress a decrease in brightness. The number of quantum dots contained in one light wavelength conversion particle is 100,000 to 500,000 times the cross section of 20 light wavelength conversion particles at random using a transmission electron microscope or a scanning transmission electron microscope. The number of quantum dots contained in one light wavelength conversion particle is calculated from the obtained cross-sectional image, and the average value of the calculated number of quantum dots is calculated.

Each of the light wavelength conversion particles 1 and 5 contains two or more quantum dots 3, and the average distance between the quantum dots 3 in the quantum dots 3 contained in one light wavelength conversion particle 1 is 1 nm or more. Is preferable. By setting the average distance between the quantum dots to 1 nm or more, concentration quenching that causes quenching due to energy transfer between the quantum dots is less likely to occur, so that a decrease in luminous efficiency can be suppressed. The average distance between the quantum dots was obtained by randomly photographing the cross sections of 20 light wavelength conversion particles with a transmission electron microscope or a scanning transmission electron microscope at a magnification of 100,000 to 500,000 times. The distance between the quantum dots is calculated from the image of, and the average value of the calculated distances between the quantum dots is calculated. It is more preferable that the upper limit of the average distance between the quantum dots 3 in the quantum dots 3 is 100 nm or less.

<Resin particles>
The resin particles 2 contain at least one of a specific element and a carboxylic acid. The specific element or carboxylic acid does not have to be fixed in the resin particles 2, but from the viewpoint of preventing the elution of the specific element or carboxylic acid, it is formed in the resin particles 2 by bonding with the resin constituting the resin particles 2. It is preferably fixed. When at least one of a specific element and a carboxylic acid is fixed to the resin constituting the resin particles 2, the specific compound preferably has a polymerizable functional group. Examples of the polymerizable functional group include an ethylenically unsaturated group such as a (meth) acryloyl group, a vinyl group and an allyl group, an epoxy group, an isocyanate group, or a hydroxyl group. When at least one of the specific compound and the carboxylic acid contains an isocyanate group as a polymerizable functional group, the polymerizable compound used for forming the resin constituting the resin particles 2 contains a hydroxyl group, and the specific compound and the carboxylic acid When at least one of the above contains a hydroxyl group as a polymerizable functional group, the polymerizable compound used for forming the resin constituting the resin particles 2 preferably contains an isocyanate group. When the specific compound contains a polymerizable functional group, it can be polymerized with the polymerizable compound, and at least one of the specific element and the carboxylic acid can be immobilized in the resin particles 2. When the specific compound contains a polymerizable functional group, the specific compound may contain one or more polymerizable functional groups, but may contain two or more.

Whether or not the resin particles 2 contain a specific element or carboxylic acid can be confirmed as follows. First, as will be described later, a ligand composed of a sulfur-based compound, a phosphorus-based compound, a nitrogen-based compound, a carboxyl group-containing compound, or the like is bound to the surface of the shell of the quantum dot. Even when an element or carboxylic acid is detected, the detected specific element or carboxylic acid is not necessarily the specific element or carboxylic acid contained in the resin particles. On the other hand, the ligand of the quantum dot is bound to the surface of the shell, and the size of the coordination site of the ligand is usually within about 1 nm, so that the ligand does not exist at a position separated from the surface of the shell by 3 nm or more. Therefore, a specific element is detected by X-ray photoelectron spectroscopy (XPS) or energy dispersive X-ray analysis (EDS) at an arbitrary position on the surface or inside of the resin particle at a distance of 3 nm or more from the surface of the shell of the quantum dot. If carboxylic acid is detected by microinfrared spectroscopic analysis (IR), it can be determined that the resin particles contain a specific element or carboxylic acid.

<Quantum dot>
Since the quantum dots 3 are the same as those described in the column of quantum dots, the description thereof will be omitted here. The quantum dots 3 shown in FIGS. 1 and 2 are composed of a first quantum dot 3A and a second quantum dot 3B having an emission band in a wavelength range different from that of the first quantum dot 3A. There is.

<Coat layer>
The coat layer 4 covers the surface of the resin particles 2. The function of the coat layer 4 is not particularly limited, but for example, the coat layer 4 has a function of maintaining the shape of the resin particles, a function of preventing the components in the resin particles from being eluted from the particles, and a dispersion liquid or composition in the resin particles. At least one of the permeation prevention function of the components inside, the barrier property imparting function to oxygen and water vapor, the antireflection function of the excitation light incident on the resin particles, and the resin particle dispersibility imparting function when prepared as a dispersion liquid or composition. Has a function.

The film thickness of the coat layer 4 depends on the function exhibited by the coat layer 4, but is preferably 10 nm or more and 5000 nm or less, preferably 20 nm, from the viewpoint of ease of production and an appropriate size of the resin particles. More preferably 1000 nm or less. In particular, when the coat layer 4 exerts a barrier property-imparting function, the film thickness of the coat layer 4 is 50 nm or more and 1000 nm or less from the viewpoint of preventing cracks in the coat layer while maintaining the barrier property. preferable. Further, when the coat layer 4 exhibits an antireflection function and the refractive index satisfies the relationship of binder resin <coat layer <resin particle relationship or binder resin> coat layer> resin particles, which will be described later, the light wavelength conversion particles. It is more preferable that the thickness of the coat layer 4 is 50 nm or more and 300 nm or less from the viewpoint of suppressing reflection on the surface of 1 and efficiently incorporating the excitation light into the resin particles 2. For the film thickness of the coat layer 4, a scanning electron microscope (SEM) was used to photograph a cross section of the light wavelength conversion particle 1, and the film thickness of the coat layer was measured at 20 points in the image of the cross section, and the film thickness of the coat layer 4 was measured at 20 points. The average value of the film thickness.

According to the present embodiment, since suspension polymerization is carried out using a solution containing a suspension stabilizer and having a viscosity of 0.02 Pa · s or more and 10 Pa · s or less, the average particle size is small and the average particle size is small. It is possible to obtain light wavelength conversion particles 1 and 5 having a small variation in particle size. That is, since the suspension stabilizer is used, the dispersibility of the mixture for light wavelength conversion particles can be improved, so that the average particle size of the light wavelength conversion particles can be reduced and the viscosity of the solution can be reduced to 0. Since it is set to .02 Pa · s or more and 10 Pa · s or less, the shear stress at the time of stirring is evenly applied to the mixture for light wavelength conversion particles, and the variation in particle size can be reduced.

It is considered that the reason why quantum dots are easily deteriorated by heat resistance test and moisture heat resistance test is as follows. First, as described above, a ligand composed of a sulfur-based compound, a phosphorus-based compound, or the like is coordinated on the surface of the quantum dot, and this ligand is easily desorbed by light or heat. When the ligand is desorbed from the quantum dots, water and oxygen are likely to adhere to the quantum dots, so that the quantum dots are oxidized and deteriorated. As a result, it is considered that the quantum dots are deteriorated by the heat resistance test and the moisture heat resistance test. On the other hand, in the present embodiment, since the light wavelength conversion particles are formed by using a specific compound, the resin particles 2 that enclose the quantum dots 3 are selected from the group consisting of sulfur, phosphorus, and nitrogen. It contains at least one of one or more elements and a carboxylic acid. Therefore, at least one of a sulfur component, a phosphorus component, a nitrogen component and a carboxylic acid can be present in the vicinity of the quantum dots 3, whereby excellent heat resistance and moist heat resistance can be obtained. This is a function that at least one of the sulfur component, the phosphorus component, the nitrogen component and the carboxylic acid present in the resin particle 2 assists the role of the ligand even when the ligand is desorbed from the quantum dots ( For example, it binds to quantum dots instead of ligands and exerts at least one of the functions of substituting the ligand and capturing oxygen), which is considered to be because the deterioration of the quantum dots is suppressed. ..

According to the present embodiment, since the light wavelength conversion particles 1 and 5 contain at least one of a specific element and a carboxylic acid, excellent heat resistance and moist heat resistance can be obtained for the above reasons. Further, since the average particle size of the light wavelength conversion particles 1 and 5 is 10 μm or less, the average particle size of the light wavelength conversion particles is small, and the standard deviation of the particle size distribution of the light wavelength conversion particles is 8 μm or less. The variation in the particle size of the light wavelength conversion particles is also small. Thereby, the light wavelength conversion particles 1 and 5 having good dispersibility can be obtained.

When quantum dots are encapsulated in glass particles, the infiltration of water and oxygen can be suppressed, but since they are brittle, defects due to cracks are likely to occur during manufacturing, processing, heat resistance test, and moisture heat resistance test. , It is difficult to obtain light wavelength conversion particles with stable quality. On the other hand, in the present embodiment, since the quantum dots 3 are included in the resin particles 2, it has excellent flexibility and can suppress defects due to cracks. Thereby, the light wavelength conversion particles 1 and 5 having stable quality can be provided.

<<< Light wavelength conversion particle-containing composition >>>
The light wavelength conversion particle-containing composition contains light wavelength conversion particles. The composition containing light wavelength conversion particles preferably contains, in addition to the light wavelength conversion particles, a polymerizable compound that becomes a binder resin described later after curing. In this case, the light wavelength conversion particle-containing composition may further contain a polymerization initiator in addition to the light wavelength conversion particles and the polymerizable compound. The light wavelength conversion particle-containing composition preferably further contains light-scattering particles, and may also contain additives and solvents.

The light wavelength conversion particle-containing composition may contain a suspension stabilizer. Since the composition containing the light wavelength conversion particles contains the suspension stabilizer, it can be confirmed that the suspension stabilizer was used in the production of the light wavelength conversion particles. The suspension stabilizer may be present in the light wavelength conversion particle-containing composition, in the light wavelength conversion particles, or outside the light wavelength conversion particles. Whether or not the light wavelength conversion particle-containing composition contains a suspension stabilizer can be confirmed as follows. The composition containing light wavelength conversion particles is placed in hot water at 95 ° C. and stirred at a stirring speed of 500 rpm for 120 minutes. The stirred water is filtered and the filtrate is dried at 90 ° C. for 10 hours. The solid matter obtained by drying is analyzed by infrared spectroscopic analysis (IR) or nuclear magnetic resonance spectroscopic analysis (NMR spectroscopic analysis). This makes it possible to confirm whether or not the suspension stabilizer is contained in the composition containing the light wavelength conversion particles.

When the light wavelength conversion layer is formed by using the light wavelength conversion particle-containing composition, the viscosity of the light wavelength conversion particle-containing composition is preferably 10 mPa · s or more and 10000 mPa · s or less. If the viscosity of the light wavelength conversion particle-containing composition is less than 10 mPa · s, it may be difficult to form a sufficient film thickness, and if it exceeds 10000 mPa · s, the light wavelength conversion particle-containing composition is formed. When applying, it becomes difficult to apply, and the leveling property may deteriorate. The lower limit of the viscosity of the light wavelength conversion particle-containing composition is preferably 10 mPa · s or more, and the upper limit of the viscosity of the light wavelength conversion particle-containing composition is preferably 10000 mPa · s or less.

The content of the light wavelength conversion particles with respect to the total solid content mass of the light wavelength conversion particle-containing composition is preferably 1% by mass or more and 40% by mass or less, and more preferably 3% by mass or more and 30% by mass or less. .. If the content of the light wavelength conversion particles is less than 1% by mass, sufficient emission intensity may not be obtained, and if the content of the light wavelength conversion particles exceeds 40% by mass, processing during film formation May be difficult.

The content of the polymerizable compound with respect to the total solid content mass of the light wavelength conversion particle-containing composition is preferably 30% by mass or more, and preferably 50% by mass or more and 99% by mass or less. By setting the content of the polymerizable compound to 30% by mass or more, sufficient curability can be obtained when the light wavelength conversion particle-containing composition is cured. When the light wavelength conversion particle-containing composition contains both a radical-polymerizable compound and a cationically polymerizable compound, the above-mentioned content means the total content of the radical-polymerizable compound and the cationically polymerizable compound. To do.

<< Light wavelength conversion particles >>
Since the light wavelength conversion particles contained in the light wavelength conversion particle-containing composition are the light wavelength conversion particles described above, the description thereof will be omitted here.

<< Polymerizable compounds and polymerization initiators >>
Since the polymerizable compound and the polymerization initiator are the same as the polymerizable compound and the polymerization initiator described in the resin particles 2, the description thereof will be omitted here. When a light source described later is formed using the light wavelength conversion particle-containing composition, the polymerizable compound in the light wavelength conversion particle-containing composition is an epoxy compound from the viewpoint of sealing the light emitter in the light source. It is preferably a polysiloxane compound having a silanol group and / or an alkoxysilyl group.

<< Light-scattering particles >>
The light scattering particles are particles having an action of changing the traveling direction of light by scattering the light that has entered the light wavelength conversion layer or the light wavelength conversion unit, which will be described later.

The average particle size of the light-scattering particles is, for example, preferably 0.1 μm or more and 10 μm or less, and more preferably 0.3 μm or more and 5 μm or less. If the average particle size of the light scattering particles is less than 0.1 μm, the light wavelength conversion efficiency of the light wavelength conversion sheet may be insufficient, and the light scattering particles must have sufficient light scattering properties. It is necessary to increase the amount of addition. On the other hand, when the average particle size of the light-scattering particles exceeds 10 μm, the number of light-scattering particles decreases even if the addition amount (mass%) is the same, so that the number of scattering points decreases and a sufficient light-scattering effect is obtained. I can't get it.

The light-scattering particles may be organic particles such as acrylic resin particles, styrene resin particles, melamine resin particles, and urethane resin particles, but the rate of change in brightness before and after the heat resistance test can be reduced, and light can be used. Inorganic particles are preferable because the incident light on the wavelength conversion sheet can be suitably scattered and the light wavelength conversion efficiency with respect to the incident light can be preferably improved.

Inorganic particles include aluminum-containing compounds such as _{Al 2} O _{3 , zirconium-containing compounds such as ZrO 2} , tin-containing compounds such as antimony-doped tin oxide (ATO) and indium tin oxide (ITO), and magnesium such as _{MgO and MgF 2.} At least one compound selected from the group consisting of compounds, titanium-containing compounds such as _{TiO 2} and BaTiO ₃ , antimony-containing compounds such as _{Sb 2} O _{5 , silicon-containing compounds such as SiO 2, and zinc-containing compounds such as ZnO.} Particles can be mentioned. Since these inorganic particles can increase the difference in refractive index from the binder resin, they are also preferable from the viewpoint of obtaining a large Mie scattering intensity. Since the light wavelength conversion efficiency with respect to the incident light can be more preferably improved by the light wavelength conversion sheet 10, the light scattering particles may be made of two or more kinds of materials.

The content of the light scattering particles with respect to the total solid content mass of the light wavelength conversion particle-containing composition is preferably 1% by mass or more and 50% by mass or less, and more preferably 3% by mass or more and 30% by mass or less. .. By setting the content of the light-scattering particles to 1% by mass or more, a sufficient light-scattering effect can be obtained, and by setting the content of the light-scattering particles to 50% by mass or less, Mie scattering can be achieved. Since it is likely to occur, a sufficient light scattering effect can be obtained, and a decrease in workability can be suppressed.

<<< Light wavelength conversion member >>>
The light wavelength conversion member includes a cured product of the light wavelength conversion particle-containing composition. The shape and structure of the light wavelength conversion member can be appropriately changed depending on the location where the light wavelength conversion member is incorporated or the like. For example, the light wavelength conversion member may be a light wavelength conversion sheet as described below, a light source described later, or a light wavelength conversion layer installed in the vicinity of the light source.

<<< Light wavelength conversion sheet >>>
The light wavelength conversion sheet 10 shown in FIG. 3 is a form of a light wavelength conversion member, which converts the wavelength of a part of the incident light into another wavelength, and the other part of the incident light and the incident light. It is a sheet that emits wavelength-converted light. The light wavelength conversion sheet 10 shown in FIG. 3 includes a light wavelength conversion layer 11, light transmitting base materials 12 and 13 provided on both sides of the light wavelength conversion layer 11, and light in the light transmitting base materials 12 and 13. It includes light diffusion layers 14 and 15 provided on the side opposite to the surface on the wavelength conversion layer 11 side.

In the light wavelength conversion sheet 10, the surfaces of the light diffusion layers 14 and 15 constitute the surfaces 10A and 10B of the light wavelength conversion sheet 10. The light wavelength conversion sheet 10 includes the light-transmitting base materials 12 and 13, but does not have a barrier layer, so that it does not have a barrier film composed of the light-transmitting base material and the barrier layer. The light wavelength conversion sheet 10 has a structure of a light diffusion layer 14 / a light transmission base material 12 / a light wavelength conversion layer 11 / a light transmission base material 13 / a light diffusion layer 15, but is a light wavelength conversion layer. The structure of the optical wavelength conversion sheet is not particularly limited as long as it has.

In the optical wavelength conversion sheet 10, as shown in FIG. 4, when light is incident from the surface 10A of the optical wavelength conversion sheet 10, the light L1 incident on the quantum dots 4 in the optical wavelength conversion layer 11 is generated. It is converted into light L2 having a wavelength different from that of light L1 and emitted from the surface 10B. On the other hand, even when light is incident from the surface 10A, the light L1 passing between the quantum dots 4 in the optical wavelength conversion layer 11 is emitted from the surface 10B without being wavelength-converted.

In the light wavelength conversion sheet 10, since the light wavelength conversion particles 1 provide excellent heat resistance and moisture heat resistance, the entire sheet has a water vapor transmittance (WVTR: Water Vapor Transmission Rate) at 40 ° C. and 90% relative humidity. There may become a 0.1g ^/ (m 2 · 24h) or more. The water vapor permeability is a numerical value obtained by a method based on JIS K7129: 2008. The water vapor transmission rate can be measured using a water vapor transmission rate measuring device (product name "PERMATRAN-W3 / 31", manufactured by MOCON). Since a barrier film is formed on the conventional light wavelength conversion sheet, the light wavelength conversion sheet 10 has a higher water vapor transmission rate than the conventional light wavelength conversion sheet, that is, the light wavelength conversion sheet 10 has a higher water vapor transmission rate. Moisture is more easily transmitted than the conventional light wavelength conversion sheet. As will be described later, when the light wavelength conversion sheet includes an optical member in addition to the light wavelength conversion layer, the water vapor transmittance is the water vapor transmittance of the entire light wavelength conversion sheet including the optical member.

In the light wavelength conversion sheet 10, since the light wavelength conversion particles 1 provide excellent heat resistance and moisture heat resistance, the oxygen transmission rate (OTR: Oxygen Transmission Rate) at 23 ° C. and 90% relative humidity is obtained in the entire sheet. ^{0.1cm 3 / (m 2 · 24h} · atm) may be equal to or greater than. The light wavelength conversion sheet 10 may satisfy the water vapor transmittance and the oxygen transmittance at the same time. The oxygen permeability is a numerical value obtained by a method based on JIS K7126: 2006. The oxygen permeability can be measured using an oxygen gas permeability measuring device (product name "OX-TRAN 2/21", manufactured by MOCON). Since a barrier film is formed on the conventional light wavelength conversion sheet, the light wavelength conversion sheet 10 has a higher oxygen transmission rate than the conventional light wavelength conversion sheet, that is, the light wavelength conversion sheet 10 has a higher oxygen transmission rate. Compared to the conventional light wavelength conversion sheet, not only water but also oxygen is easily transmitted. Similarly to the above, when the light wavelength conversion sheet includes an optical member in addition to the light wavelength conversion layer, the oxygen transmittance is the oxygen transmittance of the entire light wavelength conversion sheet including the optical member.

40 ° C. in the optical wavelength conversion sheet 10, a water vapor transmission rate of 90% relative humidity may be made with 1g ^/ (m 2 · 24h) or more and 23 ° C. in the optical wavelength conversion sheet 10, a relative humidity of 90% oxygen permeability may be a ^{1cm 3 / (m 2 · 24h} · atm) or more.

The thickness of the optical wavelength conversion sheet 10 is preferably 10 μm or more and 500 μm or less. When the average thickness of the optical wavelength conversion sheet 10 is within this range, it is suitable for reducing the weight and thinning of the backlight device.

The thickness of the light wavelength conversion sheet 10 is determined by photographing a cross section of the light wavelength conversion sheet 10 using a scanning electron microscope (SEM), a transmission electron microscope (TEM), or a scanning transmission electron microscope (STEM). In this image, the thickness of the light wavelength conversion sheet 10 is measured at 20 points and used as the average value of the thicknesses at the 20 points. Among these, considering that the film thickness of the optical wavelength conversion sheet 10 is on the order of μm, it is preferable to use SEM. In the case of SEM, the acceleration voltage is preferably 30 kV and the magnification is preferably 1000 to 7000 times, and in the case of TEM or STEM, the acceleration voltage is preferably 30 kV and the magnification is preferably 50,000 to 300,000 times.

<< Optical wavelength conversion layer >>
The light wavelength conversion layer 11 contains the light wavelength conversion particles 1 and the binder resin 16 which is a cured product of the polymerizable compound. The light wavelength conversion layer 11 shown in FIG. 3 further contains light scattering particles 17. By including the light scattering particles 17, the light wavelength conversion efficiency can be improved. The light wavelength conversion particle 1 included in the light wavelength conversion layer 11 is the same as the light wavelength conversion particle 1 described in the above section of the light wavelength conversion particle, and the light scattering particles contained in the light wavelength conversion layer 11 Reference numeral 17 denotes the same as the light-scattering particles described in the section of the light wavelength conversion-containing particle composition, and therefore the description thereof will be omitted here.

In the light wavelength conversion layer 11, the content of the specific element in the light wavelength conversion layer 11 measured by fluorescent X-ray analysis (XRF) is preferably 0.5% by mass or more. By setting the content of a specific element to 0.5% by mass or more, deterioration of quantum dots can be further suppressed. The content of a specific element can be measured by using a fluorescent X-ray analyzer (product name "EDX-800HS", manufactured by Shimadzu Corporation). The lower limit of the content of the specific element in the optical wavelength conversion layer 11 measured by X-ray fluorescence analysis (XRF) is more preferably 1% by mass or more, and the upper limit of the content of the specific element is 20% by mass. It is more preferably% or less, and further preferably 10% by mass or less. If the content of a specific element exceeds 20% by mass, sufficient curing may not be performed when the light wavelength conversion layer is formed.

The film thickness of the optical wavelength conversion layer 11 is preferably 10 μm or more and 200 μm or less. When the average thickness of the light wavelength conversion layer 11 is within this range, it is suitable for reducing the weight and thinning of the backlight device. For the film thickness of the light wavelength conversion layer 11, a cross section of the light wavelength conversion layer 11 is photographed using a scanning electron microscope (SEM), and the film thickness of the light wavelength conversion layer 11 is measured at 20 points in the image of the cross section. , The average value of the film thickness at the 20 points. The upper limit of the average film thickness of the optical wavelength conversion layer 11 is more preferably less than 170 μm.

<Binder resin>
As the binder resin 16, a cured product of a polymerizable compound can be used. As the polymerizable compound, the same polymerizable compound as that described in the section of the light wavelength conversion particle-containing composition can be used, and thus the description thereof will be omitted here.

<< Light-transmitting base material >>
The thicknesses of the light-transmitting substrates 12 and 13 are not particularly limited, but are preferably 10 μm or more and 300 μm or less. If the thickness of the light transmissive substrates 12 and 13 is less than 10 μm, there is a risk of wrinkles and breaks during assembly and handling of the optical wavelength conversion sheet, and if it exceeds 300 μm, the weight of the display and the thin film may be reduced. It may not be suitable for conversion. The more preferable lower limit of the thickness of the light-transmitting substrates 12 and 13 is 50 μm or more, and the more preferable upper limit is 200 μm or less.

The thickness of the light transmitting base materials 12 and 13 is determined by using a scanning electron microscope (SEM), a transmitting electron microscope (TEM) or a scanning transmitting electron microscope (STEM) to obtain a cross section of the light transmitting base materials 12 and 13. Is taken, and the thicknesses of the light-transmitting substrates 12 and 13 are measured at 20 points in the image of the cross section, and the average value of the film thicknesses at the 20 points is used.

Examples of the constituent raw materials of the light-transmitting base materials 12 and 13 include polyester (for example, polyethylene terephthalate and polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyether sulphon, and poly sulphon. , Polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyetherketone, polymethylmethacrylate, polycarbonate, polyurethane and the like. Preferred examples of the constituent materials of the light-transmitting base materials 12 and 13 include polyester (for example, polyethylene terephthalate and polyethylene naphthalate).

<< Light diffusion layer >>
The light diffusion layers 14 and 15 have an uneven shape on the surface, and the uneven shape can diffuse the light incident on the light wavelength conversion sheet 10 and the light emitted from the light wavelength conversion sheet 10. By providing the light diffusion layers 14 and 15, the light wavelength conversion efficiency of the light wavelength conversion sheet 10 can be further improved. The light diffusing layers 14 and 15 contain light scattering particles and a binder resin.

<Light scattering particles>
The light-scattering particles in the light-diffusing layers 14 and 15 are mainly for forming an uneven shape on the surface of the light-diffusing layers 14 and 15 and exhibiting a light-scattering function.

The average particle size of the light-scattering particles in the light diffusing layers 14 and 15 is, for example, preferably 1 μm or more and 30 μm or less, and more preferably 1 μm or more and 20 μm or less. If the average particle size of the light-scattering particles is less than 1 μm, the light wavelength conversion efficiency of the light wavelength conversion sheet may be insufficient, and the amount of the light-scattering particles added in order to obtain sufficient light diffusivity. Need to be increased. On the other hand, when the average particle size of the light-scattering particles exceeds 30 μm, the light diffusing performance becomes excellent, but the light transmittance of the light diffusing layer tends to be significantly reduced.

The light scattering particles may be particles made of an organic material or particles made of an inorganic material. The organic material constituting the light-scattering particles is not particularly limited, and for example, polyester, polystyrene, melamine resin, (meth) acrylic resin, acrylic-styrene copolymer resin, silicone resin, benzoguanamine resin, benzoguanamine / formaldehyde condensation resin. , Polycarbonate, polyethylene, polyolefin and the like. Of these, crosslinked acrylic resin is preferably used. The inorganic material constituting the light diffusing particles is not particularly limited, and examples thereof include inorganic oxides such as silica, alumina, titania, tin oxide, antimony-doped tin oxide (ATO), and zinc oxide fine particles. Of these, silica and / or alumina are preferably used.

<Binder resin>
As the binder resin of the light diffusion layers 14 and 15, a cured product of a polymerizable compound can be used. As the polymerizable compound, the same polymerizable compound as that described in the column of the coat layer can be used, and thus the description thereof will be omitted here.

<< Manufacturing method of optical wavelength conversion sheet >>
The optical wavelength conversion sheet 10 can be produced, for example, as follows. First, a composition for a light diffusing layer containing light scattering particles and a polymerizable compound is applied to one surface of the light transmitting base material 12 and dried to form a coating film of the composition for a light diffusing layer. .. Similarly, a coating film of the composition for the light diffusion layer is formed on one surface of the light transmissive base material 13.

Next, the coating film of the composition for the light diffusion layer is cured by light irradiation or the like. As a result, the light diffusing layer 14 is formed on one surface of the light transmitting base material 12, and the light transmitting base material 12 with the light diffusing layer 14 is formed. Further, in the same manner, the light transmissive base material 13 with the light diffusion layer 15 is formed.

After forming the light-transmitting base material 13 with the light-diffusing layer 15, the above-mentioned light wavelength conversion particle-containing composition is formed on the surface of the light-transmitting base material 13 with the light-diffusing layer 15 opposite to the surface on the light-transmitting layer 15 side. The material is applied and dried to form a coating of the composition containing light wavelength conversion particles.

After forming the coating film of the light wavelength conversion particle-containing composition, the surface of the light transmissive substrate 12 with the light diffusion layer 14 opposite to the surface on the light diffusion layer 14 side is the coating film of the light wavelength conversion particle-containing composition. The light transmitting base material 12 with the light diffusing layer 14 is arranged on the coating film of the light wavelength conversion particle-containing composition so as to be in contact with the light diffusing layer 14. As a result, the coating film of the light wavelength conversion particle-containing composition is sandwiched between the light-transmitting base materials 12 and 13.

Next, the coating film of the light wavelength-converting particle-containing composition is heated through the light-transmitting substrate 12 or the coating film is irradiated with ionizing radiation to cure the light-wavelength-converted particle-containing composition mixture. The light wavelength conversion layer 11 is formed, and the light wavelength conversion layer 11 is integrated with the light transmitting base material 12 with the light diffusing layer 14 and the light transmitting base material 13 with the light diffusing layer 15. As a result, the optical wavelength conversion sheet 10 shown in FIG. 3 is obtained.

<< Other optical wavelength conversion sheets >>
As shown in FIG. 5, the optical wavelength conversion sheet may be an optical wavelength conversion sheet 20 having only the optical wavelength conversion layer 11 (single layer structure). Further, as shown in FIG. 6, the light wavelength conversion sheet may be a light wavelength conversion sheet 30 including a light wavelength conversion layer 11 and a light transmissive base material 31 that supports the light wavelength conversion layer 11. .. By providing the light transmissive base material 31, the intensity of the light wavelength conversion sheet can be increased as compared with the light wavelength conversion sheet 20.

<Light transmissive base material>
As the light-transmitting base material 31 of the light wavelength conversion sheet 30, the same materials as those of the light-transmitting base materials 12 and 13 can be used, and thus the description thereof will be omitted here.

<< Other optical wavelength conversion sheets >>
As shown in FIGS. 7 and 8, the optical wavelength conversion sheet is arranged on at least one surface side of the optical wavelength conversion layer 11 and the optical wavelength conversion layer 11, and is integrated with the optical wavelength conversion layer 11. The optical wavelength conversion sheet 40 including the optical member 41 may be used.

<Optical member>
As used herein, the term "optical member" refers to optical properties (for example, polarization, photorefraction, light scattering, light reflection, light transmission, light absorption, photodiffraction, diversion, etc.). It is not particularly limited as long as it is a sheet (film) -shaped or plate-shaped member having optical characteristics. Examples of the optical member include an optical plate such as a lens sheet, a light guide plate and a light diffusing plate, a reflective polarizing separation sheet, a polarizing plate and the like. When the optical member sheets are provided on both sides of the optical wavelength conversion sheet, the optical members may be optical members having different optical characteristics. In this embodiment, an example in which the optical member is a lens sheet will be described.

As shown in FIGS. 7 and 8, the optical member 41 includes a light-transmitting base material 42 and a lens layer 43 provided on one surface of the light-transmitting base material 42. As shown in FIGS. 7 and 8, the lens layer 43 includes a sheet-shaped main body 44 and a plurality of unit lenses 45 arranged side by side on the light emitting side of the main body 44. The light transmissive base material 42, the lens layer 43, the main body 44, and the unit lens 45 have the same configurations as the light transmissive base material 111, the lens layer 112, the main body 113, and the unit lens 114, which will be described later. Therefore, the description thereof will be omitted here.

In the optical wavelength conversion sheet 40, the optical wavelength conversion layer 11 and the optical member 41 are integrated by directly applying and curing the optical wavelength conversion particle-containing composition on one surface of the optical member 41. The optical wavelength conversion layer 11 and the optical member 41 may be bonded to each other via an adhesive layer.

<< Other optical wavelength conversion sheets >>
As shown in FIG. 9, the optical wavelength conversion sheet may be an optical wavelength conversion sheet 50 including an optical wavelength conversion layer 11 and overcoat layers 51 and 52 covering both surfaces of the optical wavelength conversion layer 11. In the present embodiment, the overcoat layers 51 and 52 are formed on both sides of the light wavelength conversion layer 11, but if the overcoat layer is formed on at least one surface of the light wavelength conversion layer, the light wavelength conversion is performed. It does not have to be formed on both sides of the layer 11. When the overcoat layer is provided only on one surface of the light wavelength conversion layer, a light transmitting base material may be provided on the other surface of the light wavelength conversion layer.

<Overcoat layer>
The overcoat layers 51 and 52 are layers made of a resin that covers the surface of the light wavelength conversion layer 11 and is formed by coating. Other layers such as a light diffusion layer may be formed on the overcoat layers 51 and 52.

The overcoat layers 51 and 52 are provided to prevent the light wavelength conversion layer 11 from being directly exposed to the atmosphere. By providing such overcoat layers 51 and 52 on at least one surface of the light wavelength conversion layer 11, the quantum dots 3 can be more protected from moisture and oxygen, and the light transmissive substrate can be converted to light wavelength. The thickness of the light wavelength conversion sheet can be made thinner than that provided on at least one surface of the layer 11.

The overcoat layers 51 and 52 may have some function other than the function of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere. Specifically, the overcoat layers 51 and 52 may be, for example, a layer having at least one of functions such as antiblocking property, light diffusing property, antistatic property, and antireflection property. When the overcoat layers 51 and 52 are layers having a function of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere and some other function, the overcoat layers 51 and 52 are for having some function. The material may be added.

The film thickness of the overcoat layers 51 and 52 is 0.1 μm or more and 100 μm or less from the viewpoint of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere and thinning the light wavelength conversion sheet. Is preferable. The film thicknesses of the overcoat layers 51 and 52 can be measured by the same method as the film thickness of the optical wavelength conversion layer 11. The lower limit of the film thickness of the overcoat layers 51 and 52 is more preferably 1 μm or more, and the upper limit is more preferably 50 μm or less.

The overcoat layers 51 and 52 are not particularly limited, and include, for example, (meth) acrylate compounds, epoxy compounds, combinations of isocyanates and polyols, metal alkoxides, silicon-containing resins, water-soluble polymers, or mixtures thereof. It can be formed using a composition for a coat layer. Among these, the overcoat layers 61 and 62 are zinc acrylate, a hydrolysis product of alkoxysilane, polyvinyl alcohol, polysilazane, or these, from the viewpoint of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere. It is preferably formed using a composition for an overcoat layer containing a mixture.

In the optical wavelength conversion sheet 20, 30, 40, 50, the entire sheet, 40 ° C., water vapor transmission rate of 90% relative humidity may be a 0.1g ^/ (m 2 · 24h) or more. In the optical wavelength conversion sheet 20, 30, 40, 50, the entire sheet, 23 ° C., even oxygen permeability at a relative humidity of 90% has become a ^{0.1cm 3 / (m 2 · 24h} · atm) or higher Good. 40 ° C. in the optical wavelength conversion sheet 20, 30, 40, 50, the water vapor transmission rate of 90% relative humidity may be made with 1g ^/ (m 2 · 24h) or more, the optical wavelength conversion sheet 20, 30, 23 ° C. in 40 and 50, the oxygen permeability at 90% relative humidity may be a ^{1cm 3 / (m 2 · 24h} · atm) or more.

<< Other optical wavelength conversion sheets >>
The light wavelength conversion sheet may be a light wavelength conversion sheet 60 as shown in FIG. In this case, the water vapor transmittance and the oxygen transmittance of the light wavelength conversion sheet 60 do not have to be within the above-mentioned ranges.

The light wavelength conversion sheet 60 shown in FIG. 10 is the light wavelength conversion layer 11, the barrier films 61 and 62 provided on both sides of the light wavelength conversion layer 11, and the light wavelength conversion layer 11 side of the barrier films 61 and 62. It is provided with light diffusion layers 13 and 14 provided on the side opposite to the surface. In the light wavelength conversion sheet 60, the surfaces of the light diffusion layers 13 and 14 constitute the surfaces 60A and 60B of the light wavelength conversion sheet 60.

<Barrier film>
The barrier films 61 and 62 are members for suppressing the permeation of water and oxygen to protect the quantum dots 3 from water and oxygen. Here, the "barrier film" herein is a member alone, 40 ° C., water vapor transmission rate of 90% relative humidity becomes 0.1g ^/ (m 2 · 24h) below, and 23 ° C., relative humidity oxygen transmission rate at 90% is intended to mean a member made of a ^{0.1cm 3 / (m 2 · 24h} · atm) of less than. The barrier film includes not only a single-layer structure film but also a multi-layer structure film. By installing the barrier films 61 and 62 with the light wavelength conversion layer 11 sandwiched between them, the heat resistance and moisture resistance of the quantum dots 3 can be further improved. The barrier films 61 and 62 shown in FIG. 10 are provided on the light transmissive base materials 12 and 13 and the light wavelength conversion layer 11 side of the light transmissive base materials 12 and 13, and suppress the permeation of water and oxygen. It includes barrier layers 63 and 64 having a function.

Water vapor permeability of the barrier film 61,62 (WVTR: Water Vapor Transmission Rate ) is, 40 ° C., at a relative humidity of ^{90%, 1.0 × 10 -2 g} / (m 2 · 24h) that less is Is more preferable. The water vapor transmission rate can be measured using a water vapor transmission rate measuring device (product name "PERMATRAN-W3 / 31", manufactured by MOCON).

Oxygen permeability of the barrier film 61,62 (OTR: Oxygen Transmission Rate) is, 23 ° C., at a relative humidity of ^{90%, 1.0 × 10 -2 cm} 3 / (m 2 · 24h · atm) or less It is more preferable to have. The oxygen permeability can be measured using an oxygen gas permeability measuring device (product name "OX-TRAN 2/21", manufactured by MOCON).

(Barrier layer)
The barrier layers 63 and 64 are composed of a thin-film deposition layer having a function of suppressing the permeation of water and oxygen. The thin-film deposition layer is a layer formed by a vapor deposition method such as a physical vapor deposition (PVD) method such as a sputtering method or an ion plating method or a chemical vapor deposition (CVD) method. The thin-film deposition layer has the advantage that the barrier property can be enhanced.

The material for forming the thin-film vapor deposition layer is not particularly limited as long as it can be vapor-deposited by a thin-film deposition method and has a barrier property, and examples thereof include inorganic oxides such as silicon oxide and aluminum oxide, and metals.

The film thickness of the thin-film deposition layer is not particularly limited, but is preferably 0.01 μm or more and 1 μm or less. If the film thickness of the thin-film vapor deposition layer is less than 0.01 μm, the barrier performance of the thin-film deposition layer may be insufficient, and if it exceeds 1 μm, the barrier performance may be easily deteriorated due to cracks in the thin-film deposition layer. is there. The more preferable lower limit of the thickness of the vapor-deposited layer is 0.03 μm or more, and the more preferable upper limit is 0.5 μm or less.

The film thickness of the thin-film deposition layer is determined by photographing the cross section of the optical wavelength conversion sheet 60 using a scanning electron microscope (SEM), measuring the film thickness of the vapor-deposited film at 20 points in the image of the cross section, and measuring the film thickness at 20 points. The average thickness. Further, the thin-film deposition layer may be a single layer or a laminated layer of a plurality of layers. When a plurality of thin-film vapor deposition layers are laminated, each layer constituting the thin-film deposition layer may be directly laminated or laminated.

The optical wavelength conversion sheets 10, 20, 30, 40, 50, 60 can be used by being incorporated in a backlight device and an image display device. Hereinafter, an example in which the light wavelength conversion sheet 10 is incorporated into a backlight device and an image display device will be described. 11 is a schematic configuration diagram of an image display device including the backlight device according to the present embodiment, FIG. 12 is a perspective view of the lens sheet shown in FIG. 11, and FIG. 13 is a perspective view of the lens sheet of FIG. It is sectional drawing along line II. 14 and 16 are schematic configuration diagrams of other backlight devices according to the present embodiment, FIG. 15 is a schematic configuration diagram of the light source shown in FIG. 14, and FIG. 17 is a schematic configuration diagram of the optical plate shown in FIG. It is an enlarged view near the light entry surface.

<<< Image display device >>>
The image display device 80 shown in FIG. 11 includes a backlight device 90 and a display panel 130 arranged on the light emitting side of the backlight device 90. The image display device 80 has a display surface 80A for displaying an image. In the image display device 80 shown in FIG. 11, the surface of the display panel 130 is the display surface 80A.

<< Display panel >>
The display panel 130 shown in FIG. 11 is a liquid crystal display panel, and is between the polarizing plate 131 arranged on the incoming light side, the polarizing plate 132 arranged on the light emitting side, and the polarizing plate 131 and the polarizing plate 132. It includes an arranged liquid crystal cell 133.

<< Backlight device >>
The backlight device 90 shown in FIG. 11 is configured as an edge light type backlight device, and includes a light source 100, an optical plate 105 as a light guide plate arranged on the side of the light source 100, and a light emitting side of the optical plate 105. The optical wavelength conversion sheet 10 arranged in the light wavelength conversion sheet 10, the lens sheet 110 arranged on the light source side of the light wavelength conversion sheet 10, the lens sheet 115 arranged on the light source side of the lens sheet 110, and the light source side of the lens sheet 115. It includes a reflective polarizing separation sheet 120 arranged, and a reflective sheet 125 arranged on the side opposite to the light source side of the optical plate 105. The backlight device 90 includes an optical plate 105, lens sheets 110 and 115, a reflective polarizing separation sheet 120, and a reflective sheet 125, but these sheets and the like may not be provided. In the present specification, the “light emitting side” means the side of each member where light emitted in the direction of emission from the backlight device is emitted. The backlight device incorporating the light wavelength conversion sheet 10 is not limited to the edge light type, and may be a direct type backlight device.

The surface of the optical wavelength conversion sheet 10 on the optical plate 105 side is the surface 10A (light incoming surface), and the surface of the optical wavelength conversion sheet 10 on the lens sheet 110 side is the surface 10B (light emitting surface).

<Light source>
The light source 100 includes, for example, a fluorescent lamp such as a linear cold-cathode tube, or a light emitter such as a point-shaped light emitting diode (LED) or an incandescent light bulb. In the present embodiment, the light source 100 is provided by a large number of point-shaped light emitters, specifically, a large number of light emitting diodes (LEDs), which are linearly arranged on the light receiving surface 95C side of the optical plate 105, which will be described later. ,It is configured.

Since the light wavelength conversion sheet 10 is arranged in the backlight device 90, the light source 100 can use only a light emitting body that emits light in a single wavelength range. For example, as the light source, only a blue light emitting diode that emits blue light having high color purity can be used.

<Optical plate>
The optical plate 105 as a light guide plate has a quadrangular shape in a plan view. The optical plate 105 extends between the light emitting surface 105A formed by one main surface on the display panel 130 side, the back surface 105B composed of the other main surface facing the light emitting surface 105A, and the light emitting surface 105A and the back surface 105B. Has sides. The side surface of the side surface on the light source 100 side is an incoming light surface 105C that receives light from the light source 100. The light incident on the optical plate 105 from the light entry surface 105C is guided in the optical plate in the direction connecting the light entry surface 105C and the opposite surface facing the light entry surface 105C (light guide direction), and is guided through the optical plate to the light emission surface. Emitted from 105A.

<Lens sheet>
The lens sheets 110 and 115 have a function of changing the traveling direction of the incident light and emitting the incident light from the light emitting side. In the present embodiment, as shown in FIG. 12, a function (condensing function) of changing the traveling direction of light L3 having a large incident angle and emitting it from the light emitting side to intensively improve the brightness in the front direction. At the same time, it has a function (retroreflection function) of reflecting light L4 having a small incident angle and returning it to the light wavelength conversion sheet 10 side. The lens sheets 110 and 115 include a light-transmitting base material 111 and a lens layer 112 provided on one surface of the light-transmitting base material 111.

(Light transmissive base material)
Since the light-transmitting base material 111 is the same as the light-transmitting base materials 12 and 13, the description thereof will be omitted here.

(Lens layer)
As shown in FIGS. 12 and 13, the lens layer 112 includes a sheet-shaped main body 113 and a plurality of unit lenses 114 arranged side by side on the light emitting side of the main body 113.

The main body 113 functions as a sheet-like member that supports the unit lens 114. As shown in FIGS. 12 and 13, unit lenses 114 are arranged on the light emitting side surface 113A of the main body 113 without any gap. Therefore, the light emitting surfaces 110B and 115B of the lens sheets 110 and 115 are formed by the lens surfaces. On the other hand, as shown in FIG. 13, the main body 113 has a smooth surface forming the incoming side surface of the lens layer 112 as the incoming light entering side surface 113B facing the light emitting side surface 113A.

The unit lenses 114 are arranged side by side on the light emitting side surface 113A of the main body 113. As shown in FIG. 12, the unit lens 114 extends linearly in a direction intersecting the arrangement direction AD of the unit lens 114, particularly linearly in the present embodiment. Further, in the present embodiment, a large number of unit lenses 114 included in one lens sheet 110, 115 extend in parallel with each other. Further, the longitudinal LD of the unit lenses 114 of the lens sheets 110 and 115 is orthogonal to the arrangement direction AD of the unit lenses 114 of the lens sheets 110 and 115.

The unit lens 114 may have a triangular columnar shape, or may have a wavy shape or a bowl shape such as a hemispherical shape. Specifically, examples of the unit lens include a unit prism, a unit cylindrical lens, a unit microlens, and the like. Examples of the lens sheet having such a unit lens shape include a prism sheet, a lenticular lens sheet, and a microlens sheet.

As can be understood from FIG. 11, the arrangement direction of the unit lens 114 of the lens sheet 110 and the arrangement direction of the unit lens 114 of the lens sheet 115 intersect, and more specifically, are orthogonal to each other.

<Reflective polarization separation sheet>
The reflective polarization separation sheet 120 transmits only the first linearly polarized light component (for example, P-polarized light) among the light emitted from the lens sheet 115, and is a second straight line orthogonal to the first linearly polarized light component. It has a function of reflecting polarized light components (for example, S-polarized light) without absorbing them. The second linearly polarized light component reflected by the reflective polarization separation sheet 120 is reflected again, and the polarized light is eliminated (a state in which both the first linearly polarized light component and the second linearly polarized light component are included). It is incident on the reflective polarizing separation sheet 120 again.

As the reflective polarizing separation sheet 120, "DBEF" (registered trademark) available from 3M can be used. In addition to "DBEF", a high-intensity polarizing sheet "WRPS" available from Shinwha Intertek, a wire grid polarizer, or the like can be used as the reflective polarizing separation sheet 120.

<Reflective sheet>
The reflective sheet 125 has a function of reflecting the light leaked from the back surface 105B of the optical plate 105 and causing it to enter the optical plate 105 again. The reflective sheet 125 is composed of a white diffuse reflective sheet, a sheet made of a material having a high reflectance such as metal, a sheet containing a thin film made of a material having a high reflectance (for example, a metal thin film) as a surface layer, and the like. obtain.

<< Other backlight devices >>
The backlight device 90 shown in FIG. 11 includes an optical wavelength conversion sheet 10, but the structure of the backlight device is not particularly limited as long as it includes an optical wavelength conversion member. For example, as shown in FIG. 14, the backlight device may be a backlight device 150 including a light source 160 instead of the light wavelength conversion sheet 10 and the light source 100. The light source 160 is a form of a light wavelength conversion member.

As shown in FIG. 15, the light source 160 has a substrate 161 and a reflection member 162 having an opening 162A arranged on the substrate 161 and a light emitting member arranged on the substrate 161 and in the opening 162A of the reflection member 162. A light source 163 such as a diode and an optical wavelength conversion unit 164 filled in the opening 162A of the reflection member 162 so as to cover the light source 163 are provided.

The light wavelength conversion unit 164 is different from the light wavelength conversion layer 11 in shape and arrangement, and the configuration and physical properties of the light wavelength conversion unit 164 are the same as those of the light wavelength conversion layer 11. The light wavelength conversion unit 164 is a cured product of a light wavelength conversion particle-containing composition containing the light wavelength conversion particles 1 and an epoxy compound as a polymerizable compound or a polysiloxane compound having a silanol group and / or an alkoxysilyl group. Is preferable. The light wavelength conversion unit 164 can be formed by filling the opening 162A of the reflection member 162 with the light wavelength conversion particle-containing composition and thermosetting the composition. When the light source 160 having the light wavelength conversion unit 164 is used, the structure is not particularly limited as long as the light wavelength conversion unit 164 is arranged so as to cover the light emitting body 163.

<< Other backlight devices >>
The backlight device may be the backlight device 170 shown in FIG. Specifically, the backlight device 170 shown in FIG. 16 includes a light-transmitting light wavelength conversion layer 180 arranged between the light source 100 and the optical plate 105 instead of the light wavelength conversion sheet 10. There is. The light wavelength conversion layer 180 is a form of a light wavelength conversion member.

The light wavelength conversion layer 180 is provided on the light incoming surface 105C of the optical plate 105 as shown in FIG. The optical wavelength conversion layer 180 is linearly arranged so that the longitudinal direction is along the arrangement direction of the light sources 90.

The optical wavelength conversion layer 180 is different from the optical wavelength conversion layer 11 only in the arrangement location and shape, and the configuration and physical properties of the optical wavelength conversion layer 180 are the same as those of the optical wavelength conversion layer 11. Therefore, the description thereof is omitted here. And.

According to the present embodiment, the deterioration of the quantum dots 3 can be suppressed by the resin particles 2 containing at least one of a specific element and a carboxylic acid, so that the optical wavelength conversion sheets 10, 20, 30, 40, 50 can be used. , Barrier film can be omitted. As a result, the process of the optical wavelength conversion sheet can be simplified, so that the quality can be easily improved and the optical wavelength conversion sheet can be made thinner.

In an optical wavelength conversion sheet provided with a barrier film, when a heat resistance test or a moist heat resistance test is performed, punctate defects such as pinholes and cracks are likely to occur in the barrier film. When a defect portion is generated in the barrier film, moisture or oxygen may enter from the defect portion, and some quantum dots may be deteriorated to generate a point-like reduced brightness portion (luminance defect) in the optical wavelength conversion sheet. .. This punctate luminance defect is more easily visible than in the case where the quantum dots are deteriorated as a whole and the luminance is uniformly lowered. On the other hand, according to the present embodiment, the deterioration of the quantum dots 3 can be suppressed by the resin particles 2 containing at least one of a specific element and a carboxylic acid, so that even if the barrier films 71 and 72 have defects, defects occur. Therefore, even when water or oxygen enters from this defect portion, the point-shaped brightness defect can be suppressed.

According to the present embodiment, the deterioration of the quantum dots 3 can be suppressed by the resin particles 2 containing at least one of a specific element and a carboxylic acid, and therefore, in the optical wavelength conversion sheets 10, 20, 30, 40, 50, 60, Deterioration of the quantum dots 3 existing in the peripheral portions 10C, 20A, 30A, 40A, 50A, and 60C can also be suppressed.

In the optical wavelength conversion sheet 40, since the optical wavelength conversion layer 11 and the optical member 41 are integrated, the optical wavelength conversion sheet and the optical member are simplified and thin as compared with the case where the optical wavelength conversion sheet and the optical member are arranged separately and independently. A backlight device can be obtained. That is, when the light wavelength conversion sheet and the optical member are arranged separately and independently, since an air interface exists between the light wavelength conversion sheet and the optical member, a relatively large void is created in the backlight device. It takes. On the other hand, in the present embodiment, since the light wavelength conversion layer 11 and the optical member 41 are integrated, there is no air interface between the light wavelength conversion layer 11 and the optical member 41. This makes it possible to obtain a simplified thin backlight device.

A light emitting body such as a light emitting diode also emits heat when it emits light. Therefore, normally, when the light wavelength conversion unit is incorporated in the light source or when the light wavelength conversion unit is arranged at a position close to the light source, the light wavelength conversion unit is covered in order to suppress the deterioration of the quantum dots. A barrier member is required. On the other hand, in the present embodiment, the binder resin 3 of the light wavelength conversion particles 1 in the light wavelength conversion unit 164 and the light wavelength conversion layer 180 makes the light wavelength conversion unit 164 and the light wavelength conversion layer 180 heat and moisture resistant. Therefore, deterioration of the quantum dots 4 can be suppressed without covering the light wavelength conversion unit 164 or the light wavelength conversion layer 180 with a barrier member.

In order to explain the present invention in detail, examples will be given below, but the present invention is not limited to these descriptions.

<< Manufacture of light wavelength conversion particles >>
Light wavelength conversion particles were obtained according to the following procedure.
<Example 1>
(Light wavelength conversion particle 1)
First, 47.25 parts by mass of a 10% by mass polyvinyl alcohol aqueous solution and 267.55 parts by mass of ion-exchanged water were put into a 500 ml separable flask, and the mixture was stirred with a stirring rod to bring the concentration of polyvinyl alcohol to water to 1.52. A mass%% aqueous polyvinyl alcohol solution A was obtained. When the viscosity of the obtained polyvinyl alcohol aqueous solution A at 25 ° C. was measured using a B-type viscometer (product name "TVB-10", manufactured by Toki Sangyo Co., Ltd.), the viscosity was 0.03 Pa · s. It was. The viscosities of the polyvinyl alcohol aqueous solutions B to F described later at 25 ° C. were also measured using the same viscometer as described above.

On the other hand, the disposable cup has 1.0 part by mass of green emission quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm) and red. Emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm) 1.0 part by mass and tricyclodecanedimethanol diacrylate (product) A mixture with 50 parts by mass of the name "A-DCP" (manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) was added. Next, 50 parts by mass of tetraethylene glycol bis (3-mercaptopropionate) (product name "EGMP-4", manufactured by SC Organic Chemical Co., Ltd.) and a thermal radical polymerization initiator (2) were placed in a disposable cup containing a mixture of these. , 2'-azobis (2,4-dimethylvaleronitrile), manufactured by Tokyo Kasei Kogyo Co., Ltd.) 1.0 part by mass was added and stirred to obtain a mixture 1 for light wavelength conversion particles.

Then, within 10 minutes after the tetraethylene glycol bis (3-mercaptopropionate) was added, the mixture 1 for light wavelength conversion particles was added to the polyvinyl alcohol aqueous solution A. Then, using a homogenizer, the mixture was stirred at a stirring speed of 7,000 rpm for 10 minutes and suspended. The stirring was performed in a state where the contents of the separable flask were surrounded by a wrap so that the contents of the separable flask would not be scattered.

After the suspension, a separable flask containing a polyvinyl alcohol aqueous solution A in which the mixture 1 for light wavelength conversion particles was dispersed was immersed in a water bath at 90 ° C. Then, the polyvinyl alcohol aqueous solution A in which the mixture 1 for light wavelength conversion particles was dispersed was stirred at a stirring speed of 200 rpm for 1 hour while being maintained at 90 ° C., and suspension polymerization was carried out to obtain a particulate polymer. Then, while stirring, the separable flask containing the polyvinyl alcohol aqueous solution A containing the polymer was cooled in a water bath. Next, the reaction solution was suction-filtered using a membrane filter, the residue of the filtration was washed with ion-exchanged water, and dried under reduced pressure to obtain light wavelength-converted particles 1. In the light wavelength conversion particle 1, green emission quantum dots and red emission quantum dots were included in the resin particles.

<Example 2>
(Light wavelength conversion particle 2)
The light wavelength conversion particles 2 were obtained by the same procedure as the light wavelength conversion particles 1 except that the polyvinyl alcohol aqueous solution B having a polyvinyl alcohol concentration of 4.57% by mass with respect to water was used instead of the polyvinyl alcohol aqueous solution A. It was. The polyvinyl alcohol aqueous solution B was obtained by putting 141.75 parts by mass of a 10 mass% polyvinyl alcohol aqueous solution and 182.50 parts by mass of ion-exchanged water into a 500 ml separable flask and stirring the mixture with a stirring rod. there were. When the viscosity of the obtained polyvinyl alcohol aqueous solution B at 25 ° C. was measured, the viscosity was 0.055 Pa · s.

<Example 3>
(Light wavelength conversion particle 3)
The light wavelength conversion particles 3 were obtained by the same procedure as the light wavelength conversion particles 1 except that the polyvinyl alcohol aqueous solution C having a polyvinyl alcohol concentration of 7.62% by mass with respect to water was used instead of the polyvinyl alcohol aqueous solution A. It was. The polyvinyl alcohol aqueous solution C was obtained by putting 236.25 parts by mass of a 10 mass% polyvinyl alcohol aqueous solution and 97.46 parts by mass of ion-exchanged water into a 500 ml separable flask and stirring the mixture with a stirring rod. there were. When the viscosity of the obtained polyvinyl alcohol aqueous solution C at 25 ° C. was measured, the viscosity was 0.22 Pa · s.

<Example 4>
(Light wavelength conversion particle 4)
The light wavelength conversion particles 4 were obtained by the same procedure as the light wavelength conversion particles 1 except that the polyvinyl alcohol aqueous solution D having a polyvinyl alcohol concentration of 18% by mass with respect to water was used instead of the polyvinyl alcohol aqueous solution A. The polyvinyl alcohol aqueous solution D was obtained by putting 55.81 parts by mass of polyvinyl alcohol powder and 310.08 parts by mass of ion-exchanged water into a 500 ml separable flask and stirring with a stirring rod. When the viscosity of the obtained polyvinyl alcohol aqueous solution D at 25 ° C. was measured, the viscosity was 6 Pa · s.

<Example 5>
(Light wavelength conversion particle 5)
Except for using 50 parts by mass of 2-methacryloxyethyl acid phosphate (product name "Light Ester P-2M", manufactured by Kyoeisha Chemical Co., Ltd.) instead of tetraethylene glycol bis (3-mercaptopropionate). Light wavelength conversion particles 5 were obtained by the same procedure as for light wavelength conversion particles 1.

<Example 6>
(Light wavelength conversion particle 6)
By the same procedure as for light wavelength conversion particles 1, except that 50 parts by mass of stearylamine (product name "Farmin 80", manufactured by Kao Corporation) was used instead of tetraethylene glycol bis (3-mercaptopropionate). , Light wavelength conversion particles 6 were obtained.

<Example 7>
(Light wavelength conversion particle 7)
Except for using 50 parts by mass of ω-carboxy-polycaprolactone mono (meth) acrylate (product name "M-5300", manufactured by Toagosei Co., Ltd.) instead of tetraethylene glycol bis (3-mercaptopropionate). , The light wavelength conversion particle 7 was obtained by the same procedure as that of the light wavelength conversion particle 1.

<Comparative example 1>
(Light wavelength conversion particle 8)
Light wavelength conversion particles 8 were obtained by the same procedure as for light wavelength conversion particles 1 except that tetraethylene glycol bis (3-mercaptopropionate) was not used.

<Comparative example 2>
(Light wavelength conversion particle 9)
The light wavelength conversion particles 9 were obtained by the same procedure as the light wavelength conversion particles 1 except that the polyvinyl alcohol aqueous solution E having a polyvinyl alcohol concentration of 7.62% by mass with respect to water was used instead of the polyvinyl alcohol aqueous solution A. It was. The polyvinyl alcohol aqueous solution E contains 236.25 parts by mass and ions of a 10% by mass polyvinyl alcohol aqueous solution prepared by using polyvinyl alcohol having a molecular weight lower than that of the polyvinyl alcohol used in the light wavelength conversion particles 1 in a 500 ml separable flask. It was obtained by adding 97.46 parts by mass of exchanged water and stirring with a stirring rod. When the viscosity of the obtained polyvinyl alcohol aqueous solution E at 25 ° C. was measured, the viscosity was 0.01 Pa · s.

<Comparative example 3>
(Light wavelength conversion particle 10)
The light wavelength conversion particles 10 were obtained by the same procedure as the light wavelength conversion particles 1 except that the polyvinyl alcohol aqueous solution F having a polyvinyl alcohol concentration of 20% by mass with respect to water was used instead of the polyvinyl alcohol aqueous solution A. The polyvinyl alcohol aqueous solution F was obtained by putting 62.02 parts by mass of polyvinyl alcohol powder and 310.08 parts by mass of ion-exchanged water into a 500 ml separable flask and stirring the mixture with a stirring rod. When the viscosity of the obtained polyvinyl alcohol aqueous solution F at 25 ° C. was measured, the viscosity was 12 Pa · s.

<< Adjustment of composition containing light wavelength conversion particles >>
Each component was blended so as to have the composition shown below to obtain a composition containing light wavelength conversion particles.
<Example 8>
(Composition containing light wavelength conversion particles 1)
-Light wavelength conversion particles 1:20 parts by mass-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 80 parts by mass-Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacare" Registered trademark) 184 ", manufactured by BASF Japan Ltd.): 1 part by mass

<Examples 9 to 14 and Comparative Examples 4 to 6>
(Compositions containing light wavelength conversion particles 2 to 10)
In the light wavelength conversion particle-containing compositions 2 to 10, the same composition as in the light wavelength conversion particle-containing composition 1 except that each light wavelength conversion particle shown in Table 2 was used instead of the light wavelength conversion particle 1. And said. The blending amount of the light wavelength conversion particles 2 to 10 was the same as that of the light wavelength conversion particles 1.

<Preparation of composition for light diffusion layer>
Each component was blended so as to have the composition shown below to obtain a composition 1 for a light diffusion layer.
(Composition for light diffusion layer 1)
-Pentaerythritol triacrylate: 99 parts by mass-Light scattering particles (crosslinked polystyrene resin particles, product name "SBX-4", manufactured by Sekisui Kasei Kogyo Co., Ltd., average particle diameter 4 μm): 158 parts by mass-Radical polymerization initiator (1-Hydroxycyclohexylphenyl ketone, product name "Irgacure (registered trademark) 184, manufactured by BASF Japan, Inc.): 1 part by mass / solvent (methylisobutylketone: cyclohexanone = 1: 1 (mass ratio)): 170 parts by mass

<Preparation of composition for overcoat layer>
Each component was blended so as to have the composition shown below to obtain a composition 1 for an overcoat layer.
(Composition 1 for overcoat layer)
-Zinc acrylate (product name "ZN-DA" manufactured by Nippon Catalyst Co., Ltd.): 25 parts by mass-A mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (product name "Aronix (registered trademark) M-403", Toa Synthetic Co., Ltd.): 5 parts by mass, methanol: 70 parts by mass, radical polymerization initiator (1-hydroxycyclohexylphenylketone, product name "Acrylate (registered trademark) 184, manufactured by BASF Japan Co., Ltd.): 1 part by mass

<Example 15>
The composition for the light diffusion layer 1 on one side of two polyethylene terephthalate (PET) base materials (product name "Lumilar T60", manufactured by Toray Industries, Inc.) as a light transmissive base material having a size of 7 inches and a thickness of 50 μm, respectively. Was applied to form a coating film. Next, the solvent in the coating film was evaporated by passing dry air at 80 ° C. for 30 seconds to dry the formed coating film. Then, ultraviolet rays were irradiated so that the integrated light amount was 500 mJ / cm ² , and the coating film was cured to form a light diffusing layer having a thickness of 10 μm, and a PET substrate with a light diffusing layer was formed.

Next, the light wavelength conversion particle-containing composition 1 was applied to a surface of the PET substrate with a light diffusion layer opposite to the surface on the light diffusion layer side, and dried at 80 ° C. to form a coating film. Then, the other PET substrate with a light diffusing layer was laminated on the coating film so that the surface of the PET substrate with a light diffusing layer on the other side opposite to the surface on the light diffusing layer side was in contact with the coating film. In this state, ultraviolet rays are irradiated so that the integrated light amount is 500 mJ / cm ² , and the coating film is cured to form an optical wavelength conversion layer having a film thickness of 100 μm, and the optical wavelength conversion layer and two sheets of light are formed. It was integrated with a PET substrate with a diffusion layer. As a result, the optical wavelength conversion sheet according to Example 15 was obtained.

<Examples 16 to 21 and Comparative Examples 7 to 9>
In Examples 16 to 21 and Comparative Examples 7 to 9, the same as in Example 15 except that each light wavelength conversion particle-containing composition shown in Table 3 was used instead of the light wavelength conversion particle-containing composition 1. To prepare an optical wavelength conversion sheet.

<Example 22>
A light wavelength conversion particle-containing composition 1 was applied to one surface of a 50 μm-thick polyethylene terephthalate (PET) base material (product name “Lumilar T60”, manufactured by Toray Industries, Inc.) to form a coating film. Then, it was heated at 100 ° C. to cure the coating film to form an optical wavelength conversion layer. Then, the composition 1 for the overcoat layer was applied to the surface of the light wavelength conversion layer opposite to the surface on the PET substrate side to form a coating film. Then, ultraviolet rays were irradiated so that the integrated light intensity was 500 mJ / cm ² , and the coating film was cured to obtain an overcoat layer having a film thickness of 5 μm. Next, after the PET substrate was peeled off, the composition 1 for the overcoat layer was applied to the surface of the light wavelength conversion layer opposite to the surface on the overcoat layer side to form a coating film. Then, ultraviolet rays were irradiated so that the integrated light intensity was 500 mJ / cm ² , and the coating film was cured to obtain an overcoat layer having a film thickness of 5 μm. As a result, an optical wavelength conversion sheet composed of an optical wavelength conversion layer and an overcoat layer formed on both sides of the optical wavelength conversion layer was obtained.

<Comparative Example 10>
In Comparative Example 10, a light wavelength conversion sheet was produced in the same manner as in Example 21 except that the light wavelength conversion particle-containing composition 8 was used instead of the light wavelength conversion particle-containing composition 1.

<Example 23>
A prism layer composition containing urethane acrylate is uniformly applied to one surface of a 100 μm-thick polyethylene terephthalate (PET) substrate (product name “Lumilar T60”, manufactured by Toray Industries, Inc.) to form a prism layer composition. A coating film was formed to form a laminate for a prism sheet. Then, the traveling speed of the prism sheet laminate is such that the coating film of the lens layer composition is on the molding mold side in the rotating molding mold having recesses having a shape opposite to the desired unit prism shape. The shape of the unit prism is formed on the coating film of the prism layer composition by supplying at 20 m / min with a molding die, and light such as ultraviolet rays is applied to the coating film of the prism layer composition via the PET substrate. Irradiation was performed to cure the coating film of the composition for the prism layer. Finally, the cured coating film of the prism layer composition was peeled off from the molding mold together with the PET base material to obtain a prism sheet having a prism layer formed on one surface of the PET base material. The prism layers are arranged side by side on the sheet-shaped main body and each of them extends in a direction intersecting the arrangement direction, the apex angle is 90 °, the width is 47 μm, and the height is high. It had a plurality of triangular columnar unit prisms having a height of 30 μm.

Next, the light wavelength conversion particle-containing composition 1 was applied to the surface of the prism sheet opposite to the surface of the PET substrate on the prism layer side to form a coating film. Then, by heating at 100 ° C. to cure the coating film, an optical wavelength conversion layer having a film thickness of 100 μm integrated with the prism sheet was formed. As a result, the optical wavelength conversion sheet according to Example 23 was obtained.

<Comparative Example 11>
In Comparative Example 11, a light wavelength conversion sheet was produced in the same manner as in Example 23, except that the light wavelength conversion particle-containing composition 8 was used instead of the light wavelength conversion particle-containing composition 1.

<Example 24>
First, two barrier films were prepared by the following method. In a high-frequency sputtering apparatus, polyethylene terephthalate as a light-transmitting substrate having a size of 7 inches and a thickness of 50 μm is generated by applying a high-frequency power of 13.56 MHz and a power of 5 kW to the electrodes to generate an electric discharge in the chamber. A silica-deposited layer made of a target substance (silica), having a thickness of 50 nm and a refractive index of 1.46, was formed on one side of a (PET) base material (product name “Lumilar T60”, manufactured by Toray Co., Ltd.). As a result, two barrier films having a silica-deposited layer formed on one surface of the PET base material were formed.

Next, the composition 1 for the light diffusion layer was applied to the surface of both barrier films opposite to the surface on the silica-deposited layer side to form a coating film. Next, the solvent in the coating film was evaporated by passing dry air at 80 ° C. for 30 seconds to dry the formed coating film. Then, an ultraviolet ray was irradiated so that the integrated light amount was 500 mJ / cm ² , and the coating film was cured to form a light diffusing layer having a thickness of 10 μm, and a barrier film with a light diffusing layer was formed.

Next, the light wavelength conversion particle-containing composition 1 was applied to the silica-deposited layer side of one of the barrier films with a light diffusion layer to form a coating film. Then, the other barrier film with a light diffusion layer was laminated on the surface of the silica vapor deposition layer of the barrier film with a light diffusion layer in the coating film so that the silica vapor deposition layer was in contact with the surface. In this state, the coating film was cured by heating at 100 ° C. to form a light wavelength conversion layer having a film thickness of 100 μm in close contact with both barrier films with light diffusion layers. As a result, the optical wavelength conversion sheet according to Example 24 was obtained.

<Comparative Example 12>
In Comparative Example 12, a light wavelength conversion sheet was produced in the same manner as in Example 24, except that the light wavelength conversion particle composition 8 was used instead of the light wavelength conversion particle-containing composition 1.

<Measurement of average particle size of light wavelength conversion particles and calculation of standard deviation of particle size distribution>
Light wavelengths in the optical wavelength conversion particles 1 to 10 obtained in Examples 1 to 7 and Comparative Examples 1 to 3 and the optical wavelength conversion particle-containing compositions 1 to 10 according to Examples 8 to 14 and Comparative Examples 4 to 6. The average particle size of the converted particles 1 to 10 was measured, and the standard deviation of the particle size distribution of the light wavelength converted particles was determined. Specifically, the average particle size of the light wavelength conversion particles is calculated by measuring the particle size of 20 light wavelength conversion particles in the observation of the light wavelength conversion particles with a scanning electron microscope (SEM) and calculating the average value. The standard deviation of the particle size distribution of the light wavelength-converted particles was calculated based on the particle size distribution of the light-wavelength-converted particles measured when the average particle size was obtained. In addition, "-" in the column of average particle diameter and standard deviation in Table 1 and Table 2 means that the light wavelength conversion particle was too large to measure.

<Confirmation of specific elements and carboxylic acids in resin particles in light wavelength conversion particles>
Light wavelengths in the optical wavelength conversion particles 1 to 10 obtained in Examples 1 to 7 and Comparative Examples 1 to 3 and the optical wavelength conversion particle-containing compositions 1 to 10 according to Examples 8 to 14 and Comparative Examples 4 to 6. In the converted particles 1 to 10, it was confirmed whether or not the above-mentioned specific element or carboxylic acid was detected from the resin particles of the light wavelength converted particles. Specifically, first, in the light wavelength conversion particle-containing compositions 1 to 10, the light wavelength conversion particles 1 to 10 were taken out from the light wavelength conversion particle-containing compositions 1 to 10, respectively. Then, in the light wavelength conversion particles 1 to 10 obtained in Examples 1 to 7 and Comparative Examples 1 to 3, and the light wavelength conversion particle-containing compositions 1 to 10 according to Examples 8 to 14 and Comparative Examples 4 to 6. For the optical wavelength conversion particles 1 to 10, using an energy dispersion type X-ray analyzer (product name "JEM-2800" ( ^{equipped with 100 mm 2} silicon drift detector (SDD)), manufactured by JEOL Ltd.), an acceleration voltage of 100 kV and Whether at least one of sulfur element, phosphorus element, and nitrogen element is detected at an arbitrary position on the surface or inside of the resin particle at a distance of 3 nm or more from the surface of the shell of the quantum dot under the condition of the measurement time of 30 seconds. I confirmed whether it was. In addition, using an infrared microscope (product name "Nicolet iN10", manufactured by Thermo Fisher Scientific), carboxylic acid is detected on the surface of resin particles at a distance of 3 nm or more from the surface of the quantum dot shell or at any position inside. I confirmed whether it would be done. The confirmation criteria are as follows.
◯: Any of sulfur element, phosphorus element, nitrogen element and carboxylic acid was detected.
X: None of sulfur element, phosphorus element, nitrogen element and carboxylic acid was detected.

<Evaluation of dispersibility of light wavelength conversion particles>
The dispersibility of the light wavelength conversion particles 1 to 10 was evaluated by observing the light wavelength conversion particle-containing compositions 1 to 10 according to Examples 8 to 14 and Comparative Examples 4 to 6. The evaluation criteria are as follows.
◯: Aggregation of the light wavelength conversion particles was not observed, or some agglutination was observed, but the level was not a problem in practical use.
X: Many agglutination of light wavelength conversion particles were confirmed.

<Measurement of content of specific elements>
Light wavelengths in the optical wavelength conversion particles 1 to 10 obtained in Examples 1 to 7 and Comparative Examples 1 to 3 and the optical wavelength conversion particle-containing compositions 1 to 10 according to Examples 8 to 14 and Comparative Examples 4 to 6. In the converted particles 1 to 10, the content of a specific element contained in the light wavelength converted particles 1 to 10 was measured using a fluorescent X-ray analyzer (product name "EDX-800HS", manufactured by Shimadzu Corporation). .. The content of the specific element was taken as the average value obtained by measuring the content of the specific element in 20 light wavelength conversion particles.

<Measurement of water vapor permeability and oxygen permeability>
The water vapor transmittance and the oxygen transmittance were measured in the light wavelength conversion sheets according to Examples 15 to 24 and Comparative Examples 7 to 12, respectively. The water vapor transmittance of the optical wavelength conversion sheet is 40 ° C. and 90% relative humidity using a water vapor transmittance measuring device (product name "PERMATRAN-W3 / 31", manufactured by MOCON) in accordance with JIS K7129: 2008. It was measured under the conditions of. The oxygen transmittance of the optical wavelength conversion sheet is 23 ° C. relative to the oxygen gas transmittance measuring device (product name "OX-TRAN 2/21", manufactured by MOCON) in accordance with JIS K7126: 2006. It was measured under the condition of 90% humidity.

<Measurement of brightness maintenance rate after heat resistance test>
In the light wavelength conversion sheets according to Examples 15 to 24 and Comparative Examples 7 to 12, a heat resistance test was performed in which the light wavelength conversion sheet was left in an environment of 80 ° C. for 500 hours, and before the heat resistance test on the light wavelength conversion sheet. The maintenance rate of the brightness after the heat resistance test with respect to the brightness of the light was investigated. Specifically, first, a Kindle Fire (registered trademark) HDX7 backlight device was prepared, and the optical wavelength conversion sheet before the heat resistance test was incorporated into this backlight device. This backlight device includes a blue light emitting diode having an emission peak wavelength of 450 nm, a light guide plate, a first prism sheet, and a second prism sheet in this order.

In Examples 15 to 22 and 24 and Comparative Examples 7 to 10 and 12, the light guide plate is arranged so that the blue light emitting diode side is the light inlet surface, and Examples 15 to 22 and 24 are placed on the light emission surface of the light guide plate. A backlight device was obtained by arranging the light wavelength conversion sheet, the first prism sheet, and the second prism sheet according to Comparative Examples 7 to 10 and 12 in this order. The second prism sheet was arranged so that the arrangement direction of the unit prisms was orthogonal to the arrangement direction of the unit prisms of the first prism sheet.

In Example 23 and Comparative Example 11, the light guide plate is arranged so that the blue light emitting diode side is the light incoming surface, and the prism surface of the prism sheet is on the light emitting surface of the light emitting plate so that the light emitting side is the light emitting side. The light wavelength conversion sheet and the second prism sheet according to Comparative Example 11 were arranged in this order to obtain a backlight device. The second prism sheet was arranged so that the arrangement direction of the unit prisms was orthogonal to the arrangement direction of the unit prisms of the prism sheets in the optical wavelength conversion sheet according to Example 23 and Comparative Example 11. In this way, a backlight device incorporating the optical wavelength conversion sheet according to Example 23 and Comparative Example 11 was obtained.

Then, the blue light emitting diode of the backlight device incorporating the light wavelength conversion sheet is turned on, blue light is irradiated to one surface of the light wavelength conversion sheet, and the backlight device is passed through the other surface of the light wavelength conversion sheet. The brightness of the light emitted from the light emitting surface (the surface of the second prism sheet) is measured from the thickness direction of the light wavelength conversion sheet using a spectral emission brightness meter (product name "CS2000", manufactured by Konica Minolta). The measurement was performed under the condition of an angle of 1 °.

Next, the light wavelength conversion sheet before the heat resistance test was removed from the backlight device, and the light wavelength conversion sheet was subjected to a heat resistance test in which the light wavelength conversion sheet was left in an environment of 80 ° C. for 500 hours. Then, the light wavelength conversion sheet after the heat resistance test was incorporated into the backlight device in the same manner as described above. In this state, in the same manner as described above, one surface of the light wavelength conversion sheet is irradiated with blue light, and the light emitting surface of the backlight device (the surface of the second prism sheet) passes through the other surface of the light wavelength conversion sheet. ) Was measured from the thickness direction of the optical wavelength conversion sheet using a spectral radiance meter (product name "CS2000", manufactured by Konica Minolta) under the condition of a measurement angle of 1 °.

From these measured brightnesss, the retention rate of the brightness after the heat resistance test with respect to the brightness before the heat resistance test was determined. The brightness retention rate is such that the brightness maintenance rate is A, the brightness of the light emitted from the light emitting surface of the backlight device before the heat resistance test is B, and the brightness of the light emitted from the light emitting surface of the backlight device after the heat resistance test is B. Was C, and it was calculated by the following formula.
A = C / B x 100

<Measurement of brightness maintenance rate after moisture resistance test>
In the optical wavelength conversion sheets according to Examples 15 to 24 and Comparative Examples 7 to 12, a moisture and heat resistance test was performed in which the optical wavelength conversion sheet was left in an environment of 60 ° C. and a relative humidity of 90% for 500 hours, and the optical wavelength conversion sheet was performed. The maintenance rate of the brightness after the moisture resistance test was investigated with respect to the brightness before the moisture resistance test. Specifically, first, a Kindle Fire (registered trademark) HDX7 backlight device was prepared, and an optical wavelength conversion sheet before the moisture resistance test was incorporated into this backlight device in the same manner as in the above heat resistance test.

Then, the blue light emitting diode of the backlight device incorporating the light wavelength conversion sheet is turned on, blue light is irradiated to one surface of the light wavelength conversion sheet, and the backlight device is passed through the other surface of the light wavelength conversion sheet. The brightness of the light emitted from the light emitting surface (the surface of the second prism sheet) is measured from the thickness direction of the light wavelength conversion sheet using a spectral emission brightness meter (product name "CS2000", manufactured by Konica Minolta). The measurement was performed under the condition of an angle of 1 °.

Next, the light wavelength conversion sheet before the moisture heat resistance test is removed from the backlight device, and the light wavelength conversion sheet is subjected to a heat resistance test in which the light wavelength conversion sheet is left in an environment of 60 ° C. and 90% relative humidity for 500 hours. It was. Then, the light wavelength conversion sheet after the moisture resistance test was incorporated into the backlight device in the same manner as described above. In this state, in the same manner as described above, one surface of the light wavelength conversion sheet is irradiated with blue light, and the light emitting surface of the backlight device (the surface of the second prism sheet) passes through the other surface of the light wavelength conversion sheet. ) Was measured from the thickness direction of the optical wavelength conversion sheet using a spectral radiance meter (product name "CS2000", manufactured by Konica Minolta) under the condition of a measurement angle of 1 °.

From these measured luminances, the retention rate of the luminance after the moisture resistance test was determined with respect to the luminance before the moisture resistance test. The brightness retention rate is such that the brightness maintenance rate is D, the brightness of the light emitted from the light emitting surface of the backlight device before the moisture resistance test is E, and the brightness of the light emitted from the light emitting surface of the backlight device after the moisture resistance test is E. Was F, and it was calculated by the following formula.
D = F / E × 100

<Evaluation of point-shaped brightness defects>
Using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the heat resistance test according to Examples 15 to 24 and Comparative Examples 7 to 12, there is a point-like brightness defect on the light emitting surface at the time of light emission in the backlight device. The presence was visually observed and evaluated. Further, using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the moisture resistance test according to Examples 15 to 24 and Comparative Examples 7 to 12, similarly, a point is formed on the light emitting surface at the time of light emission in the backlight device. It was visually observed and evaluated whether or not there was a defect in the brightness of the shape. The evaluation criteria are as follows.
◯: No point-shaped luminance defect was confirmed.
Δ: Several point-shaped luminance defects were confirmed.
X: Many point-shaped luminance defects were confirmed.

<Measurement of deterioration width of the peripheral edge of the optical wavelength conversion sheet>
Using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the heat resistance test according to Examples 15 to 24 and Comparative Examples 7 to 12, the brightness distribution on the light emitting surface at the time of light emission in the backlight device is determined by the light wavelength. The measurement was performed from the thickness direction of the conversion sheet using a 2D color luminance meter (product name "UA-200", manufactured by Topcon Techno House Co., Ltd.). Then, from the measured brightness distribution of the light emitting surface, the position of the light emitting surface (luminance 80% position) at which the brightness is 80% with respect to the brightness of the central portion of the light emitting surface is obtained, and is closest to the brightness 80% position on the light emitting surface. The shortest distance from the edge to the position where the brightness is 80% was obtained. Then, the shortest distance was randomly obtained for 20 places, and the average value of the shortest distances at these 20 places was taken as the deterioration width of the peripheral portion of the optical wavelength conversion sheet. Further, using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the moisture resistance test according to Examples 15 to 24 and Comparative Examples 7 to 12, the brightness distribution of the light emitting surface is measured in the same manner to emit light. Find the position of the light emitting surface (luminance 80% position) where the brightness is 80% of the brightness of the central part of the surface, and find the shortest distance from the end closest to the brightness 80% position on the light emitting surface to the brightness 80% position. It was.

The results are shown in Tables 1 to 4 below.

The results will be described below. As can be seen from Table 1, the light wavelength conversion particles 1 to 7 according to Examples 1 to 7 have a smaller average particle size and smaller variation than the light wavelength conversion particles 9 and 10 according to Comparative Examples 2 and 3. It was. Further, as can be seen from Table 2, the light wavelength conversion particles 1 to 7 contained in the light wavelength conversion particle-containing compositions 1 to 7 according to Examples 8 to 14 are the light wavelength conversion according to Comparative Examples 5 and 6. The average particle size was smaller and the variation was smaller than that of the light wavelength conversion particles 9 and 10 contained in the particle-containing compositions 9 and 10. The light wavelength-converting particles 10 contained in the light-wavelength-converting particles 10 according to Comparative Example 3 and the light-wavelength-converting particle-containing composition 10 according to Comparative Example 6 are gel-like lumps due to too high viscosity. Is formed, which is considered to have caused the particle size to become too large.

Further, as can be seen from Table 2, in the light wavelength conversion particle-containing compositions 1 to 7 according to Examples 8 to 14, light is higher than in the light wavelength conversion particle-containing compositions 9 and 10 according to Comparative Examples 5 and 6. The dispersibility of the wavelength conversion particles was excellent.

Further, as can be seen from Tables 3 and 4, in the optical wavelength conversion sheet according to Examples 15 to 23, the optical wavelength in which the quantum dots are contained in the resin particles containing at least one of a specific element and a carboxylic acid. Since the conversion particles 1 to 7 are used, the resin particles containing the quantum dots are used, but the optical wavelength conversion according to Comparative Examples 7, 10 and 11 in which the resin particles do not contain any specific element or carboxylic acid. Compared with the sheet, the brightness retention rate after the heat resistance test and the moisture heat resistance test was higher. Further, in the light wavelength conversion sheet according to Example 24, since the light wavelength conversion particles 1 in which the quantum dots are contained in the resin particles containing at least one of a specific element and the carboxylic acid are used, the quantum dots are used. Brightness maintenance rate after heat resistance test and moisture heat resistance test as compared with the light wavelength conversion sheet according to Comparative Example 12, which uses the encapsulated resin particles but the resin particles do not contain any specific element or carboxylic acid. Was expensive. This means that the light wavelength conversion particles 1 to 7 according to Examples 1 to 7 have high heat resistance and moisture heat resistance, and at least one of a specific element and a carboxylic acid can suppress deterioration of quantum dots. There is.

Since the barrier film was not used in the optical wavelength conversion sheets according to Examples 15 to 23 and Comparative Examples 7 to 11, no punctate luminance defect was confirmed. Further, in the light wavelength conversion sheet according to Example 24, although a barrier film is used, the light wavelength conversion particles 1 in which quantum dots are contained in resin particles containing at least one of a specific element and a carboxylic acid are used. Since it was used, no punctate brightness defect was confirmed. On the other hand, in the optical wavelength conversion sheet according to Comparative Example 12, which uses resin particles containing quantum dots, but the resin particles do not contain any specific element or carboxylic acid, a point-like luminance defect was confirmed. Was done. This means that at least one of the specific element and the carboxylic acid in the resin particles can suppress the deterioration of the quantum dots.

In the light wavelength conversion sheets according to Examples 15 to 23, since the light wavelength conversion particles 1 to 7 in which the quantum dots are contained in the resin particles containing at least one of a specific element and a carboxylic acid are used, the peripheral edge is used. Deterioration of the part was suppressed. On the other hand, in the optical wavelength conversion sheet according to Comparative Examples 7, 10 and 11, which uses resin particles containing quantum dots, but the resin particles do not contain any specific element or carboxylic acid, the peripheral portion thereof is used. Deterioration was confirmed. This suppresses the deterioration of quantum dots even in an environment where quantum dots are exposed to a large amount of oxygen or water vapor, such as at the periphery, if the resin particles contain at least one of a specific element and a carboxylic acid. It means that you can do it. Further, in the light wavelength conversion sheet according to Comparative Example 12, the deterioration of the central portion was relatively suppressed by the barrier film, but the deterioration of the peripheral portion was not suppressed.

In the light wavelength conversion particles 1 to 6 according to Examples 1 to 6 and the light wavelength conversion particles 1 to 6 contained in the light wavelength conversion particle-containing compositions 1 to 6 according to Examples 8 to 13, by fluorescent X-ray analysis. The measured content of the specific element was 0.5% by mass or more. On the other hand, in the light wavelength conversion particles 8 according to Comparative Example 1 and the light wavelength conversion particles 8 contained in the light wavelength conversion particle-containing composition 8 according to Comparative Example 4, specific elements measured by fluorescent X-ray analysis are used. The content of each was less than 0.5% by mass. In the light wavelength conversion particles 8, although the mixture for light wavelength conversion particles used for forming the light wavelength conversion particles 8 does not contain a specific element, the content of the specific element is 0 mass. The reason why it is not% is considered to be that the quantum dots themselves contained a sulfur component.

In the above example, CdSe is used as the core material of the green light emitting quantum dots and the red light emitting quantum dots, but even if a non-Cd material such as InP or InAs is used as the core material, the same result as in the above example is obtained. was gotten.

1, 5 ... Light wavelength conversion particles 2 ... Resin particles 3 ... Quantum dots 4 ... Coat layers 10, 20, 30, 40, 50, 60 ... Light wavelength conversion sheet 11 ... Light wavelength conversion layer 16 ... Binder resin 17 ... Light scattering Sex particles 70 ... Image display devices 80, 150, 170 ... Backlight devices

Claims (12)

A method for producing light wavelength conversion particles containing light-transparent resin particles and quantum dots contained in the resin particles.
A solution containing a suspension stabilizer and having a viscosity at 25 ° C. of 0.02 Pa · s or more and 10 Pa · s or less, quantum dots, polymerizable compounds, sulfur-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds, and carboxylic acids. A method for producing light wavelength conversion particles, which comprises a step of mixing one or more compounds selected from the group consisting of acids and a mixture containing a polymerization initiator to carry out suspension polymerization. The method for producing light wavelength conversion particles according to claim 1, wherein the suspension stabilizer is a nonionic water-soluble polymer. Light wavelength conversion particles
Wherein sulfur, phosphorus, and a light transparent resin particles containing one or more elemental selected from the group consisting of nitrogen, and a quantum dot encapsulated in said resin particles,
The average particle size of the light wavelength conversion particles is 10 μm or less.
Standard deviation of the particle size distribution of the optical wavelength conversion particle state, and are 8 [mu] m or less,
A light wavelength conversion particle having a content of the element in the light wavelength conversion particle of 0.5% by mass or more . A composition containing light wavelength conversion particles, which comprises the light wavelength conversion particles according to claim 3. The light wavelength conversion particle-containing composition according to claim 4, further comprising a suspension stabilizer. A composition containing light wavelength conversion particles, which comprises light wavelength conversion particles.
The light wavelength conversion particles are a light-transmitting resin particle containing at least one of one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen and a carboxylic acid, and a quantum encapsulated in the resin particle. Including dots
The average particle size of the light wavelength conversion particles is 10 μm or less.
The standard deviation of the particle size distribution of the light wavelength conversion particles is 8 μm or less.
An optical wavelength conversion particle-containing composition further comprising a suspension stabilizer. The light wavelength conversion particle-containing composition according to any one of claims 4 to 6, further comprising a polymerizable compound. A light wavelength conversion member comprising a cured product of the light wavelength conversion particle-containing composition according to claim 7. A light wavelength conversion sheet comprising a light wavelength conversion layer made of a cured product of the light wavelength conversion particle-containing composition according to claim 7. 40 ° C., water vapor transmission rate at a relative humidity of 90% 0.1g ^/ (m 2 · 24h) or higher and 23 ° C., the oxygen permeability at a relative humidity of 90% ^{0.1cm 3 / (m 2 · 24h} · atm ) The optical wavelength conversion sheet according to claim 9 , which satisfies at least one of the above. Light source and
A backlight device comprising the light wavelength conversion member according to claim 8 or the light wavelength conversion sheet according to claim 9 , which receives light from the light source. An image display device including the light wavelength conversion member according to claim 8 , the light wavelength conversion sheet according to claim 9 , or the backlight device according to claim 11.

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