JP2018013672A - Production method of optical wavelength conversion particle, optical wavelength conversion particle, optical wavelength conversion particle-containing composition, optical wavelength conversion member, optical wavelength conversion sheet, backlight device, and image display deice - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of optical wavelength conversion particles, by which optical wavelength conversion particles having excellent heat resistance and moisture heat resistance, a small average particle diameter and little variation in the particle diameter can be obtained, optical wavelength conversion particles having excellent heat resistance and moisture heat resistance and showing good dispersibility, an optical wavelength conversion particle-containing composition comprising the above optical wavelength conversion particles, and an optical wavelength conversion member, an optical wavelength conversion sheet, a backlight device and an image display device including a cured product of the above optical wavelength conversion particle-containing composition.SOLUTION: A production method of optical wavelength conversion particles 1 comprising light-transmitting resin particles 2 and quantum dots 3 encapsulated in the resin particles 2 is provided, in which suspension polymerization is carried out by mixing a solution comprising a suspension stabilizer and having a viscosity of 0.02 Pa s or more and 10 Pa s or less at 25°C with a mixture comprising the quantum dots 3, a polymerizable compound, at least one compound selected from the group consisting of a sulfur-containing compound, a phosphorus-containing compound, a nitrogen-containing compound, and carboxylic acid, and a polymerization initiator.SELECTED DRAWING: Figure 1

Description

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

  2. Description of the Related Art A transmissive image display device such as a liquid crystal display device generally includes a backlight device that is disposed on the back side of a transmissive image display panel such as a liquid crystal display panel and illuminates the transmissive image display panel.

  Currently, in order to improve color reproducibility, it has been studied to incorporate a light wavelength conversion member including 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 from the quantum dot mainly depends on the particle diameter of the quantum dot. Therefore, in an image display device incorporating a light wavelength conversion member, various colors can be reproduced while using a light source that projects light in a single wavelength region. For example, when a light source that emits blue light is used, the light wavelength conversion member can absorb blue light and emit green light and red light. Since an image display device incorporating such a light wavelength conversion member has excellent color purity, it has excellent color reproducibility.

  In the light wavelength conversion member, the quantum dots are deteriorated by moisture or oxygen, and the light emission efficiency may be reduced. For this reason, in an optical wavelength conversion sheet which is one form of an optical wavelength conversion member and includes an optical wavelength conversion layer including quantum dots, a barrier for suppressing the transmission of moisture and oxygen on both surfaces 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 a barrier film, a light wavelength conversion layer, and a barrier film are laminated in this order.

JP 2015-1111518 A

  However, a heat wavelength test in which a barrier film is provided on both sides of the light wavelength conversion layer and left in an environment of 80 ° C. for 500 hours or in an environment of 60 ° C. and 90% relative humidity for 500 hours. When the moisture and heat resistance test is performed, the quantum dot deteriorates at the peripheral portion of the light wavelength conversion sheet or the point-like defects such as pinholes and cracks in the barrier film, and the luminance is lowered. is there.

  For this reason, instead of using a barrier film or together with a barrier film, quantum dots are used by using light wavelength conversion particles in which quantum dots are encapsulated in resin particles containing a compound capable of improving heat resistance and moist heat resistance. It has been studied to suppress the deterioration of the material. However, when the average particle diameter of the light wavelength conversion particles is large and the particle diameter 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 There is a possibility that brightness unevenness may occur in the plane of the light wavelength conversion member that 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 a light wavelength conversion particle that has excellent heat resistance and heat-and-moisture resistance, has a small average particle diameter, and a small variation in particle diameter, and has excellent heat resistance and moisture resistance. Light wavelength conversion particles having thermal properties and good dispersibility, compositions containing light wavelength conversion particles including such light wavelength conversion particles, and light wavelengths including a cured product of such a composition containing light wavelength conversion particles An object is to provide a conversion member, a light wavelength conversion sheet, a backlight device, and an image display device.

  As a result of intensive research on the above problems, the inventors of the present invention have used 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 diameter and a small variation in particle diameter are obtained, and when the obtained light wavelength conversion particles are contained in the composition containing the light wavelength conversion particles Has found that the dispersibility of the light wavelength conversion particles is also improved. Further, when the light wavelength conversion particles are formed using at least one of one or more elements selected from the group consisting of sulfur-containing compounds, phosphorus-containing compounds, and nitrogen-containing compounds, and carboxylic acid, excellent heat resistance and moisture heat resistance It has been found that light wavelength conversion particles having the following can be obtained. The present invention has been completed based on such findings.

  According to one aspect of the present invention, there is provided a method for producing light wavelength conversion particles comprising light transmissive resin particles and quantum dots encapsulated in the resin particles, comprising a suspension stabilizer, and Selected from the group consisting of a solution having a viscosity at 25 ° C. of 0.02 Pa · s to 10 Pa · s, a quantum dot, a polymerizable compound, a sulfur-containing compound, a phosphorus-containing compound, a nitrogen-containing compound, and a carboxylic acid. There is provided a method for producing light wavelength conversion particles, comprising a step of mixing one or more compounds and a mixture containing a polymerization initiator to perform suspension polymerization.

  According to another aspect of the present invention, the light wavelength conversion particles include at least one of one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen, and a carboxylic acid. Including light transmissive resin particles and quantum dots encapsulated in the resin particles, wherein the light wavelength conversion particles have an average particle diameter of 10 μm or less, and a standard deviation of the particle size distribution of the light wavelength conversion particles is The optical wavelength conversion particles are characterized by being 8 μm or less.

  According to the other aspect of this invention, the composition containing light wavelength conversion particle | grains containing said light wavelength conversion particle | grains is provided.

  According to the other aspect of this invention, the light wavelength conversion member containing the hardened | cured material of said light wavelength conversion particle containing composition is provided.

  According to the other aspect of this invention, a light wavelength conversion sheet provided with the light wavelength conversion layer which consists of hardened | cured material of said light wavelength conversion particle containing composition is provided.

  According to the other aspect of this invention, a backlight apparatus provided with a light source and said light wavelength conversion member or said light wavelength conversion sheet which receives the light from the said light source is provided.

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

  According to one aspect of the present invention, it is possible to obtain light wavelength conversion particles having excellent heat resistance and moist heat resistance, a small average particle diameter, and a small variation in particle diameter. In addition, according to another aspect of the present invention, light wavelength conversion particles having excellent heat resistance and moist heat resistance and good dispersibility, and light wavelength conversion particle-containing composition comprising such light wavelength conversion particles In addition, it is possible to provide a light wavelength conversion member, a light wavelength conversion sheet, a backlight device, and an image display device containing a cured product of such a composition containing light wavelength conversion particles.

It is a schematic block diagram of the light wavelength conversion particle which concerns on embodiment. It is a schematic block diagram of the other light wavelength conversion particle 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 effect | action of the light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the other light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the other light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the other light wavelength conversion sheet which concerns on embodiment. It is sectional drawing along the II line of the light wavelength conversion sheet | seat of FIG. It is a schematic block diagram of the other light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the other light wavelength conversion sheet which concerns on embodiment. 1 is a schematic configuration diagram of an image display device including a backlight device according to an embodiment. FIG. 12 is a perspective view of the lens sheet shown in FIG. 11. It is sectional drawing along the II-II line of the lens sheet of FIG. It is a schematic block diagram of the other backlight apparatus which concerns on embodiment. It is a schematic block diagram of the light source shown by FIG. It is a schematic block diagram of the other backlight apparatus which concerns on embodiment. FIG. 17 is an enlarged view of the vicinity of a light incident surface of the optical plate shown in FIG. 16.

  Hereinafter, a method for producing light wavelength conversion particles, a light wavelength conversion-containing composition, a light wavelength conversion member, a light wavelength conversion sheet, a backlight device, and an image display device according to embodiments of the present invention will be described with reference to the drawings. To do. In this specification, terms such as “sheet” and “film” are not distinguished from each other only based on the difference in designation. Thus, for example, “sheet” is used to include a member that may also be referred to as a film, and “film” is used to include a member that may also be referred to as a sheet. FIG. 1 is a schematic configuration diagram of a light wavelength conversion particle according to this embodiment, FIG. 2 is a schematic configuration diagram of another light wavelength conversion particle according to this embodiment, and FIG. 3 is a light wavelength according to this embodiment. FIG. 4 is a schematic configuration diagram of the conversion sheet, FIG. 4 is a diagram illustrating 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 a conversion sheet, and FIG. 8 is sectional drawing along the II line of the optical wavelength conversion sheet | seat of FIG.

<<< Method for Producing Light Wavelength Conversion Particles >>>
The light wavelength conversion particles are particles that convert the wavelength of incident light to other wavelengths, and include light-transmitting resin particles and quantum dots encapsulated in the resin particles. The method for producing light wavelength conversion particles according to the present embodiment includes a suspension stabilizer, a solution having a viscosity at 25 ° C. of 0.02 Pa · s to 10 Pa · s, a quantum dot, a polymerizable compound, A mixture containing at least one compound selected from the group consisting of a sulfur-containing compound, a phosphorus-containing compound, a nitrogen-containing compound, and a carboxylic acid, and a polymerization initiator (hereinafter, this mixture is referred to as a “light wavelength conversion particle mixture”). And a step of performing suspension polymerization. Prior to suspension polymerization, it is preferable to first prepare the solution and the mixture.

<< Solution >>
The solution contains a suspension stabilizer and has a viscosity at 25 ° C. of 0.02 Pa · s to 10 Pa · s. The solution may contain a suspension aid in combination with a suspension stabilizer. 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. By setting the viscosity of the solution at 25 ° C. to 0.02 Pa · s or more, the shear stress during stirring is increased. Evenly added to the mixture for light wavelength conversion particles, it is possible to obtain light wavelength conversion particles with a small variation in particle diameter, and the viscosity of the solution at 25 ° C. is 10 Pa · s or less, so that the whole solution can be made uniform. Can be stirred. The viscosity of the solution is an 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 at 25 ° C. of the solution 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 setting 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 suspension stabilizer after drying. The lower limit of the concentration of the suspension stabilizer relative to the solvent of the 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 a solvent. Alternatively, a solution containing the suspension stabilizer may be prepared in advance, and this solution may be added 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 not substantially 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 nonionic water-soluble polymers include polyalkylene oxides such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, polyvinyl pyrrolidone, hydroxypropyl methyl cellulose, polyethylene oxide, and polyoxyethylene-polyoxypropylene block copolymers. , Polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene nonyl phenyl ether, polyethylene glycol fatty acid ester, polyoxyethylene lauryl amine and the like. Among these, polyvinyl alcohol, polyvinyl pyrrolidone, and polyoxyethylene-polyoxypropylene copolymer are preferable, and polyvinyl alcohol is most preferable.

  Examples of polyvinyl alcohol include Gohsenol NH-18, N-300, NL-05, C-500, P-610, GH-23, KH-20 (manufactured by Nippon Synthetic Chemical Industry), POVAL3-98, 5- 98, 11-98, 28-98, 60-98, 27-95, 22-88, 32-80 (made by Kuraray Co., Ltd.) and the like. 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>
Suspension aids are also known as dispersion aids, such as anionic surfactants such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, etc. And low-molecular surfactants, boric acid, sodium carbonate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium sulfate, and other water-soluble inorganic salts. 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 does not easily cause deterioration of transparency or yellowing during the molding process.

<< mixture for light wavelength conversion particles >>
The mixture for light wavelength conversion particles includes at least one compound selected from the group consisting of a quantum dot, a polymerizable compound, a sulfur-containing compound, a phosphorus-containing compound, a nitrogen-containing compound, and a carboxylic acid (hereinafter, this compound) Is referred to as a “specific compound”) and a polymerization initiator.

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

<Quantum dots>
Quantum dots are nano-sized semiconductor particles having a quantum confinement effect. The particle diameter and average particle diameter of the quantum dots are, for example, 1 nm or more and 20 nm or less. When the quantum dot absorbs light from the excitation source and reaches an energy excited state, the quantum dot 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 the quantum dot increases as the particle size decreases. That is, as the crystal size decreases, the light emission of the quantum dots shifts to the blue side, that is, to the high energy side. Therefore, by changing the particle diameter of the quantum dots, the emission wavelength can be adjusted over the entire wavelength range of the ultraviolet region, the visible region, and the infrared region. For example, when the quantum dot is composed of CdSe / ZnS described later, blue light is emitted when the particle diameter of the quantum dot is 2.0 nm or more and 4.0 nm or less, and the particle diameter of the quantum dot is 3.0 nm. When it is 6.0 nm or less, green light is emitted, and when the particle size of the quantum dots is 4.5 nm or more and 10.0 nm or less, red light is emitted. In the above, the particle diameter range of the quantum dot emitting blue light and the particle diameter range of the quantum dot emitting green light partially overlap, and the particle diameter of the quantum dot emitting green light and the red light Although the range of the particle diameter of the emitted quantum dots partially overlaps, even if the quantum dots have the same particle diameter, the emission color may vary depending on the size of the quantum dot core, so there is no contradiction. Not what you want. In this 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 It is light having a wavelength range of 590 nm to 750 nm.

  As the quantum dot, one kind of quantum dot may be used, but it is also possible to use two or more kinds of quantum dots each having an emission band in a single wavelength region by different particle diameters or materials. .

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

  The quantum dot is composed of, for example, a core made of a first semiconductor compound, a shell made of a second semiconductor compound that covers the core and is different from the first semiconductor compound, and a ligand bonded to the surface of the shell. Has been.

  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 A semiconductor crystal containing a semiconductor compound or a semiconductor such as a group V semiconductor compound, a group IV semiconductor such as Si, Ge, and Pb can be given. Alternatively, a semiconductor crystal including a semiconductor compound containing three or more elements such as InGaP can be used. Among these, semiconductor crystals such as CdS, CdSe, CdTe, InP, and InGaP are preferable from the viewpoints of ease of production and controllability of particle diameters that can obtain light emission in the visible range.

  As the second semiconductor compound constituting the shell, a semiconductor compound having a band gap higher than that of the first semiconductor compound constituting the core is preferably used so that excitons are confined in the core. Thereby, the luminous efficiency of a quantum dot can be improved. Examples of the second semiconductor compound constituting the shell include ZnS, ZnSe, CdS, GaN, CdSSe, ZnSeTe, AlP, ZnSTe, and ZnSSe.

  As a specific combination of the core-shell structure (core / shell) composed of a core and a shell, for example, CdSe / ZnS, CdSe / ZnSe, CdSe / CdS, CdTe / CdS, InP / ZnS, Gap / ZnS, Si / ZnS, Examples include InN / GaN, InP / CdSSe, InP / ZnSeTe, InGaP / ZnSe, InGaP / ZnS, Si / AlP, InP / ZnSTe, InP / ZnSSe, InGaP / ZnSTe, and InGaP / ZnSSe.

  The ligand is for stabilizing unstable quantum dots. Examples of the ligand include sulfur-containing compounds such as thiols, phosphorus-containing compounds such as phosphine 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, a spherical shape, a rod shape, a disk shape, or other shapes. The particle diameter of the quantum dots can be a true spherical value having the same volume when the shape of the quantum dots is not spherical.

  Information such as the particle diameter, average particle diameter, shape, and dispersion state of the quantum dots can be obtained by a transmission electron microscope or a scanning transmission electron microscope. In addition, since the emission color of the quantum dot changes depending on the particle diameter, the particle diameter of the quantum dot can be obtained from confirmation of the emission color of the quantum dot. In addition, the crystal structure and crystallite size of the quantum dots can be known by X-ray crystal diffraction (XRD). Furthermore, the information regarding the particle diameter etc. of a quantum dot can also be obtained with an 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 content of the quantum dots to 0.01% by mass or more based on the total mass of the polymerizable compound and the specific compound, sufficient emission intensity can be obtained, and the content of the quantum dots can be changed to the polymerizable compound. And by setting it as 2 mass% or less with respect to the total mass of a specific compound, sufficient transmitted light intensity of 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 cationic polymerizable compound.

(Radically polymerizable compound)
The radically polymerizable compound has at least one radically polymerizable functional group in the molecule. Examples of the radical polymerizable functional group include ethylenically unsaturated groups such as a (meth) acryloyl group, a vinyl group, and an allyl group. The “(meth) acryloyl group” means to include both “acryloyl group” and “methacryloyl group”.

  Examples of the radically polymerizable compound include radically polymerizable monomers, radically polymerizable oligomers, and radically polymerizable prepolymers, which can be appropriately adjusted and used.

  Examples of the radical polymerizable monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, Triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, pentaerythritol di (meth) ) Acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate Rate, dipentaerythritol hexa (meth) acrylate, glycerol (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, polyester acrylate, .omega.-carboxy - polycaprolactone mono (meth) acrylate.

  As the radical polymerizable oligomer, a polyfunctional oligomer having two or more functional groups 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. (Meth) acrylate, epoxy (meth) acrylate, etc. are mentioned.

  The radically polymerizable prepolymer has a weight average molecular weight exceeding 10,000, and the weight average molecular weight is preferably from 10,000 to 80,000, and more preferably from 10,000 to 40,000. Since the fall of coating suitability can be suppressed as a weight average molecular weight is 80,000 or less, the deterioration of the external appearance of the optical wavelength conversion member obtained can be suppressed. In the case of using a radical polymerizable prepolymer having a weight average molecular weight exceeding 80,000, it is preferable to use a mixture of the radical polymerizable monomer and the radical polymerizable oligomer. Examples of the polyfunctional radical polymerizable prepolymer include urethane (meth) acrylate, isocyanurate (meth) acrylate, polyester-urethane (meth) acrylate, and epoxy (meth) acrylate.

(Cationically polymerizable compound)
The cationically polymerizable compound has at least one cationically polymerizable functional group in the molecule. Examples of the cationic polymerizable functional group include cyclic ether groups such as epoxy groups and oxetanyl groups, vinyl ether groups, and the like.

  An epoxy compound is a compound having one or more epoxy groups in the molecule. Although it does not specifically limit as an epoxy compound, For example, a bisphenol A type epoxy compound, a bisphenol F type epoxy compound, a bisphenol S type epoxy compound, a biphenyl type epoxy compound, a fluorene type epoxy compound, a novolak phenol type epoxy compound, a cresol novolak type epoxy Compounds, aromatics such as 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 alkylene oxide adducts thereof Polyglycidyl ethers of polyhydric alcohols such as di- or triglycidyl ethers, polyethylene glycols or alkylene glycols thereof Diglycidyl ether side adduct, polypropylene glycol or polyalkylene glycol diglycidyl ether diglycidyl ether of alkylene oxide adduct thereof, and aliphatic, such as alkylene oxide. Here, as the alkylene oxide, aliphatic epoxy compounds such as ethylene oxide and propylene oxide, 3 ′, 4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 3,4-epoxycyclohexylmethyl methacrylate and the like Examples thereof include alicyclic epoxy compounds containing one or more epoxy groups and one or more ester groups in the molecule.

<Specific compounds>
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, the deterioration of the quantum dots can be further suppressed, and the content of the specific compound is set to 80% with respect to the mass of the polymerizable compound. By setting the mass% or less, sufficient curing can be performed during the formation of 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 compounds)
The sulfur-containing compound is a compound containing sulfur. Although it does not specifically limit as a sulfur containing compound, A thiol compound, a thioether compound, a disulfide compound, a thiophene compound, etc. are mentioned. When a thiol compound is used as the sulfur compound, in the resin particles, the thiol compound and the polymerizable compound preferably form a copolymer by a thiol-ene reaction. By copolymerizing the thiol compound and the polymerizable compound, the thiol compound can be fixed in the resin particles. In the case of using a thiol compound, 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 and odor suppression during coating, a secondary thiol compound 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 refers to 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. In the thiol compound, one or more thiol groups may be included in one molecule, but two or more are preferable from the viewpoint of improving heat resistance and wet 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。 Although it does not specifically limit as a thiol compound, The compound shown by following General formula (1) from the viewpoint of the sclerosis | hardenability in the case of formation of a light wavelength conversion layer, the heat resistance of a quantum dot, and heat-and-moisture resistance improvement is preferable.

In the formula, R ¹ is a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, R ² is an optionally substituted alkylene group having 1 to 10 carbon atoms, 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 for R ¹ may be linear or branched. Examples of the alkyl group for 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, 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 Group, 2-ethylbutyl group, heptyl group, octyl group, nonyl group, decyl group and the like.

The alkylene group for R ² may be linear or branched. Examples of the alkylene group for R ² include a methylene group, an ethylene group, a trimethylene group, a propylene group, and an isopropylidene group.

When the alkyl group of R ¹ or the alkylene group of R ² is substituted, examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, a carboxyl group, and a phenyl group. Examples include selected groups. Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom.

One methylene group or two or more non-adjacent methylene groups in the alkyl group of R ¹ or the alkylene group of R ² are —O—, —S—, —SO ₂ —, —CO—, —COO—, — It may be substituted with at least one group selected from the group consisting of OCO—, —NR ⁴ —, —CONR ⁴ —, —NR ⁴ CO—, —N═CH— and —CH═CH— (formula In the formula, each 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, and sulfur atoms.

Among these, R ¹ is an optionally substituted alkyl group having 1 to 5 carbon atoms 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, R ² is an optionally substituted alkylene group having 1 to 5 carbon atoms, 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 preferred. One methylene group or two or more methylene groups not adjacent to each other in the alkylene group represented by R ² may be substituted with the same group as described above.

  Specific examples of primary thiol compounds include hexanedithiol, decanedithiol, ethylene glycol bisthioglycolate, 1,4-butanediol bisthioglycolate, trimethylolpropane tristhioglycolate, pentaerythritol tetrakisthioglycolate, ethylene Glycol bis (3-mercaptopropionate), 1,2-propylene glycol bis (3-mercaptopropionate), 1,3-propylene glycol bis (3-mercaptopropionate), 1,4-butanediol bis (3-mercaptopropionate), glycerin tris (3-mercaptopropionate), trimethylolpropane tris (3-mercaptopropionate), trimethylolethane tris (3-mercaptopropionate) ), Pentaerythritol tetrakis (3-mercaptopropionate), dipentaerythritol hexakis (3-mercaptopropionate) and the like.

  Specific examples of the secondary thiol compound include 1,4-bis (3-mercaptobutyryloxy) butane, 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 tris (3-mercaptobutyrate), etc. Can be mentioned. Specific examples of the tertiary thiol compound include tert-butyl mercaptan.

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 phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphinic acid compounds, and phosphine compounds. Among these, a compound represented by the following general formula (2) is preferable from the viewpoints of curability at the time of forming the light wavelength conversion particles, heat resistance of the quantum dots, and improvement of heat and moisture resistance.

In the formula, q is an integer of 0 or 1, and R ^{5 to} R ⁷ are each independently hydrogen, a hydroxyl group, an optionally substituted linear or branched alkyl group having 1 to 30 carbon atoms, C1-C30 linear or branched alkoxy group which may be substituted, C1-C30 linear or branched alkenyl group which may be substituted, C1-C1 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 It represents a naphthyl group, an optionally substituted phenoxy group, an optionally substituted heterocyclic group, or a hydroxyl group.

When any of R ^{5 to} R ⁷ has a substituent, examples of the substituent include 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, or a heterocyclic group.

  As the heterocyclic group, pyridyl group, pyrimidinyl group, pyridazyl group, pyrazyl group, furyl group, thienyl group, oxazolyl group, isoxazolyl group, oxadiazolyl group, thiazolyl group, isothiazolyl group, imidazolyl group, triazolyl group, pyrrole group, pyrazolyl group Or a tetrazolyl group.

  Specific examples of phosphorus compounds include tris (2-ethylhexyl) phosphite, trilauryl phosphite, tris (tridecyl) phosphite, bis (decyl) pentaerythritol diphosphite, and bis (tridecyl) pentaerythritol diphosphite. , Triphenyl phosphite, trisnonyl phenyl phosphite, butyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, 2-hydroxyethyl methacrylate acid phosphate, dibutyl phosphate, dimethyl vinyl phosphate, di-2-ethylhexyl hydrogen phosphite And dioleyl hydrogen phosphite.

(Nitrogen-containing compounds)
A nitrogen-containing compound is a compound containing nitrogen. Although it does not specifically limit as a nitrogen-containing compound, From a viewpoint of the sclerosis | hardenability in the case of formation of light wavelength conversion particle | grains, the heat resistance of a quantum dot, and wet heat resistance, an amine compound is preferable. As an amine compound, any of a primary amine compound, a secondary amine compound, a tertiary amine compound, and a diamine compound may be sufficient.

  Specific examples of amine compounds include laurylamine, myristylamine, cetylamine, stearylamine, oleylamine, behenylamine, distearylamine, dimethyllaurylamine, dimethylmyristylamine, dimethylstearylamine, dilaurylmonomethylamine, and trioctylamine. And oleylpropylenediamine.

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

  The weight average molecular weight of the carboxylic acid is preferably 150 or more and 50000 or less from the viewpoint of being hardly volatile, excellent in dispersibility, and easy in workability. In this specification, the “weight average molecular weight” is a value obtained by dissolving in a solvent such as tetrahydrofuran (THF) and converting to 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 / carboxyl group number) of the carboxylic acid is preferably 150 or more and 50000 or less from the viewpoint of facilitating the presence of 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 carboxylic acid include ω-carboxy-polycaprolactone mono (meth) acrylate, monohydroxyethyl (meth) acrylate phthalate, 2-acryloyloxyethyl succinic acid, a reaction product of pentaerythritol and acrylic acid and succinic anhydride. Examples include acid reactants, 3-butenoic 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>
The polymerization initiator is a component that is decomposed by light or heat to generate radicals or ionic species to initiate or advance polymerization (crosslinking) of the polymerizable compound. Examples of the polymerization initiator include radical polymerization initiators (for example, photo radical polymerization initiators, thermal radical polymerization initiators), cationic polymerization initiators (photo cationic polymerization initiators, thermal cationic polymerization initiators), or mixtures thereof. It is done.

  Examples of the photo radical polymerization initiator include benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin ether compounds, thioxanthones, and the like.

  Examples of commercially available photo radical polymerization initiators include IRGACURE 184, IRGACURE 369, IRGACURE 379, IRGACURE 651, IRGACURE 819, IRGACURE 907, IRGACURE 2959, IRGACURE OXE01, and Lucillin TPO (all manufactured by BASF Japan 9) ADEKA), SPEEDCURE EMK (Nihon Sebel Hegner), benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether (all manufactured by Tokyo Chemical Industry Co., Ltd.) and the like.

  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, for example, a polycondensate of 4,4′-azobis (4-cyanopentanoic acid) and polyalkylene glycol. And polycondensate of 4,4′-azobis (4-cyanopentanoic acid) and polydimethylsiloxane having a terminal amino group.

  Examples of the peroxide include ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxy ester, diacyl peroxide, and peroxydicarbonate.

  Examples of commercially available thermal radical polymerization initiators include perbutyl O, perhexyl O, perbutyl PV (all manufactured by NOF Corporation), V-30, V-501, V-601, and VPE-0201. , VPE-0401, VPE-0601 (both manufactured by Wako Pure Chemical Industries, Ltd.) and the like.

  As said photocationic polymerization initiator, aromatic diazonium salt, aromatic iodonium salt, aromatic sulfonium salt etc. are mentioned, for example. Examples of commercially available photocationic polymerization initiators include Adekaoptomer SP-150 and Adekaoptomer 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. Examples of commercially available thermal cationic polymerization initiators include 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 ( Any of them may be Sanshin Chemical Co., Ltd.), CI series (Nihon Soda Co., Ltd.), etc.

  The content of the polymerization initiator in the light wavelength conversion particle mixture 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 made 10.0 mass% or less with respect to the total mass of the polymerizable compound and the specific compound, yellowing of the light wavelength conversion member can be suppressed.

<< Suspension polymerization process >>
After preparing the said solution and the said mixture for light wavelength conversion particles, the said solution and the said mixture for light wavelength conversion particles are mixed, and suspension polymerization is performed. Thereby, light consisting of light transmissive resin particles containing at least one of one or more elements selected from the group consisting of sulfur, phosphorus and nitrogen, and quantum dots encapsulated in the resin particles Wavelength converting particles are formed.

  After mixing the solution and the mixture for light wavelength conversion particles and before suspension polymerization, the mixture of the solution and the mixture for light wavelength conversion particles is stirred to disperse the mixture for light wavelength conversion particles in the solution. Is preferred. The method for dispersing the mixture for light wavelength conversion particles in the solution is not particularly limited, and examples thereof include a method of dispersing using a homogenizer.

  The suspension polymerization may be performed by irradiating with ionizing radiation such as ultraviolet rays, but is preferably performed by heating. Examples of the ionizing radiation in the present specification include visible light, ultraviolet rays, X-rays, electron beams, α rays, β rays, and γ rays.

  When suspension polymerization is carried out by heating, the temperature of the mixed solution (suspension) is preferably in the range of 40 ° C. or higher and 150 ° C. or lower. By setting the temperature of the mixed liquid to 40 ° C. or higher, the polymerization initiator can be activated, and by setting the temperature of the mixed liquid to 150 ° C. or lower, polymerizable compounds, quantum dots, light wavelength conversion particles, etc. 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 performed in an inert gas atmosphere inert to the mixture for light wavelength conversion particles, such as a nitrogen atmosphere.

  The suspension polymerization is preferably performed while stirring the mixed solution. The stirring may be performed to such an extent that the mixture for light wavelength conversion particles floats 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 centrifugal separation, and the separated light wavelength conversion particles are obtained by washing with water and drying.

  In the above, light wavelength conversion particles comprising resin particles and quantum dots encapsulated in the resin particles are obtained, but the resin particles, the quantum dots encapsulated in the resin particles, and formed on the surface of the resin particles In the case of forming light wavelength conversion particles comprising the coated layer, the coating layer is formed on the surface of the resin particles after suspension polymerization.

  Although depending on the function of the coating layer, when the coating layer has a function of maintaining the shape of the resin particles, the coating layer can be formed using, for example, a coating layer composition containing a polymerizable compound. . Since the polymerizable compound is the same as the polymerizable compound used for forming the resin particles, the description is 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 radical polymerizable compound, it may be formed using a composition for the coat layer containing the radical polymerizable compound. Preferably, when the resin particles are formed of a cationic polymerizable compound, it is preferably formed using a coating layer composition containing a cationic polymerizable compound.

<<< Light wavelength conversion particle >>>
The light wavelength conversion particle 1 is obtained by the above manufacturing method, and as shown in FIG. 1, one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen (hereinafter referred to as this element). And a resin particle 2 containing at least one of carboxylic acid and one or more quantum dots 3 encapsulated in the resin particle 2. Moreover, the light wavelength conversion particle | grains 5 provided with the coating layer 4 which covers the surface of the resin particle 2 as FIG. 2 shows may be sufficient as the light wavelength conversion particle | grains.

  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 the specific element to 0.5% by mass or more, it is possible to reliably suppress the deterioration of the quantum dots. The content of the specific element is determined by measuring the content of the specific element in the 20 light wavelength conversion particles, and taking the average value. The content of the 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 fluorescent X-ray analysis (XRF) is more preferably 1% by mass or more, and the upper limit of the content of the specific element is The content is more preferably 20% by mass or less, and further preferably 10% by mass or less. When the content of the specific element is 20% by mass or less, sufficient curing can be performed at the time of forming the light wavelength conversion particles. In addition, when light wavelength conversion particle | grains contain 2 or more types of specific elements, the said content shall mean the total content of a specific element.

  The average particle diameter of the light wavelength conversion particles 1 and 5 is preferably 10 μm or less. By setting the average particle diameter 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 diameter 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 aggregation of the particles. The average particle diameter of the light wavelength conversion particles 1 and 5 is obtained by measuring the particle diameter 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 variations can be obtained. The standard deviation of the particle size distribution of the light wavelength conversion particles can be calculated based on the particle size distribution of the light wavelength conversion particles measured when determining the average particle diameter.

  The shape of the light wavelength conversion particles 1 and 5 is not particularly limited, and is, for example, spherical (true sphere, approximately true sphere, elliptical sphere, etc.), polyhedral, rod (column, prism, etc.), flat, flake And indefinite shape. In addition, when the shape of the light wavelength conversion particle 1 is not spherical, the particle diameter of the light wavelength conversion particle 1 is a true spherical particle diameter having the same volume.

  The light wavelength conversion particles 1 and 5 preferably include one or more quantum dots 3 per one. By making the number of quantum dots contained in one light wavelength conversion particle one or more, a decrease in luminance can be suppressed. The number of quantum dots contained in one light wavelength conversion particle is a magnification of 100,000 to 500,000 times in a cross section of 20 light wavelength conversion particles randomly 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.

  The light wavelength conversion particles 1 and 5 each include two or more quantum dots 3 and the average distance between the quantum dots 3 in the quantum dots 3 included in one light wavelength conversion particle 1 is 1 nm or more. It is preferable that 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 light emission efficiency can be suppressed. The average distance between the quantum dots was obtained by photographing a cross section of 20 light wavelength conversion particles randomly at a magnification of 100,000 to 500,000 times using a transmission electron microscope or a scanning transmission electron microscope. The distance between the quantum dots is calculated from the above image, and the average value of the calculated distance between the quantum dots is calculated. The upper limit of the average distance between the quantum dots 3 in the quantum dots 3 is more preferably 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 may not be fixed in the resin particle 2, but from the viewpoint of preventing elution of the specific element or carboxylic acid, the resin element 2 is bonded to the resin particle 2 by bonding with the resin. It is preferably fixed. When fixing at least one of the specific element and the carboxylic acid to the resin constituting the resin particle 2, it is preferable that the specific compound 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, and a hydroxyl group. When at least one of the specific compound and carboxylic acid includes an isocyanate group as a polymerizable functional group, the polymerizable compound used for forming the resin constituting the resin particle 2 includes a hydroxyl group, and the specific compound and carboxylic acid When at least one of these contains a hydroxyl group as a polymerizable functional group, the polymerizable compound used for forming the resin constituting the resin particle 2 preferably contains an isocyanate group. When the specific compound contains a polymerizable functional group, it can be polymerized with the polymerizable compound to fix at least one of the specific element and the carboxylic acid in the resin particle 2. When the specific compound includes a polymerizable functional group, the specific compound only needs to include one or more polymerizable functional groups, but may include two or more.

  Whether the resin particle 2 contains a specific element or carboxylic acid can be confirmed as follows. First, as will be described later, since a ligand composed of a sulfur compound, a phosphorus compound, a nitrogen compound, or a carboxyl group-containing compound is bonded to the surface of the quantum dot shell, a specific wavelength is determined from the light wavelength conversion particles. 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, since the ligand of the quantum dot is bonded to the surface of the shell and the size of the ligand coordination site is usually within about 1 nm, it does not exist at a position 3 nm or more away from the surface of the shell. Therefore, a specific element is detected by X-ray photoelectron spectroscopy (XPS) or energy dispersive X-ray analysis (EDS) at any position inside or inside the resin particle 3 nm or more away from the surface of the quantum dot shell. If the carboxylic acid is detected by microscopic infrared spectroscopy (IR), it can be determined that the resin particles contain a specific element or carboxylic acid.

<Quantum dots>
Since the quantum dot 3 is the same as that described in the column of the quantum dot, the description is 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 region different from that of the first quantum dot 3A. Yes.

<Coat layer>
The coat layer 4 covers the surface of the resin particle 2. The function of the coating layer 4 is not particularly limited. For example, the coating layer 4 has a function of maintaining the shape of the resin particles, a function of preventing elution of the components in the resin particles to the outside of the particles, and a dispersion or composition in the resin particles. At least one of a function of preventing penetration of components therein, a function of imparting barrier properties against oxygen and water vapor, a function of preventing reflection of excitation light incident on resin particles, and a function of imparting dispersibility of resin particles when used as a dispersion or composition It 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 from the viewpoint of ease of production and appropriate resin particle size. More preferably, it is 1000 nm or less. In particular, when the coat layer 4 exhibits a barrier property-imparting function, the thickness of the coat layer 4 is preferably 50 nm or more and 1000 nm or less from the viewpoint of preventing cracks and the like of the coat layer while maintaining the barrier property. preferable. When the coating layer 4 exhibits the antireflection function and the refractive index satisfies the relationship of binder resin <coating layer <resin particle relationship or binder resin> coating layer> resin particle, which will be described later, light wavelength conversion particles From the viewpoint of suppressing reflection on one surface and efficiently incorporating excitation light into the resin particles 2, the thickness of the coat layer 4 is more preferably 50 nm or more and 300 nm or less. The film thickness of the coat layer 4 is obtained by photographing a cross section of the light wavelength conversion particle 1 using a scanning electron microscope (SEM), measuring the film thickness of the coat layer at 20 locations in the image of the cross section, The average value of the film thickness.

  According to this embodiment, since suspension polymerization is performed using a solution containing a suspension stabilizer and having a viscosity of 0.02 Pa · s to 10 Pa · s, the average particle size is small, and Light wavelength conversion particles 1 and 5 having a small variation in particle diameter can be obtained. 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 diameter of the light wavelength conversion particles can be reduced and the viscosity of the solution is reduced to 0. Since it is set to 0.02 Pa · s or more and 10 Pa · s or less, the shear stress at the time of stirring is uniformly applied to the mixture for light wavelength conversion particles, and the variation in particle diameter can be reduced.

  It is considered that the reason why the quantum dots are likely to be deteriorated by the heat resistance test or the moist heat resistance test is as follows. First, as described above, a ligand composed of a sulfur compound, a phosphorus compound, or the like is coordinated on the surface of the quantum dot, and this ligand is easily detached by light or heat. When the ligand is detached from the quantum dot, moisture and oxygen are likely to adhere to the quantum dot, and the quantum dot is oxidized and deteriorated. Thereby, it is thought that a quantum dot will deteriorate by a heat resistance test or a heat-and-moisture resistance test. On the other hand, in this embodiment, since the light wavelength conversion particles are formed 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. One or more elements and / or carboxylic acids are included. 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 heat and moisture resistance can be obtained. This is a function in which at least one of a sulfur component, a phosphorus component, a nitrogen component, and a carboxylic acid present in the resin particle 2 assists the role of the ligand even when the ligand is detached from the quantum dot ( For example, it is considered that the deterioration of the quantum dot is suppressed because it binds to the quantum dot instead of the ligand and exhibits the function of substituting the ligand and capturing oxygen. .

  According to this 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 from the above reasons. Moreover, since the average particle diameter of the light wavelength conversion particles 1 and 5 is 10 μm or less, the average particle diameter 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. There is also little variation in the particle diameter of the light wavelength conversion particles. Thereby, the light wavelength conversion particle | grains 1 and 5 with favorable dispersibility can be obtained.

  When quantum dots are encapsulated in glass particles, they can suppress the ingress of moisture and oxygen, but they are fragile, so defects due to cracks are likely to occur during manufacturing, processing, or heat and moisture resistance tests. It is difficult to obtain light wavelength conversion particles having stable quality. On the other hand, in this embodiment, since the quantum dot 3 is included in the resin particle 2, it has the outstanding softness | flexibility and can suppress the defect by a crack. Thereby, the optical wavelength conversion particle | grains 1 and 5 which have stable quality can be provided.

<<< Light wavelength conversion particle-containing composition >>>
The composition containing light wavelength conversion particles contains light wavelength conversion particles. It is preferable that the light wavelength conversion particle containing composition contains the polymerizable compound used as the binder resin mentioned later after hardening other than light wavelength conversion particle. In this case, the composition containing light wavelength conversion particles 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 contain an additive or a solvent.

  The composition containing light wavelength conversion particles may contain a suspension stabilizer. It can confirm that the suspension stabilizer was used at the time of manufacture of light wavelength conversion particle | grains because the composition containing light wavelength conversion particle | grains contains the suspension stabilizer. The suspension stabilizer only needs to be present in the composition containing the light wavelength conversion particles, may be present in the light wavelength conversion particles, or may be present 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 put in 95 ° C. hot water and stirred at a stirring speed of 500 rpm for 120 minutes. The stirred hot water is filtered and the filtrate is dried at 90 ° C. for 10 hours. The solid material obtained by drying is analyzed by infrared spectroscopy (IR) or nuclear magnetic resonance spectroscopy (NMR spectroscopy). Thereby, it can be confirmed whether the suspension stabilizer is contained in the composition containing light wavelength conversion particles.

  When the light wavelength conversion layer is formed 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 10,000 mPa · s or less. When the viscosity of the composition containing light wavelength conversion particles is less than 10 mPa · s, it may be difficult to form a sufficient film thickness. When the viscosity exceeds 10,000 mPa · s, the composition containing light wavelength conversion particles may be When applying, it may be difficult to apply and the leveling property may be deteriorated. 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 10,000 mPa · s or less.

  The content of the light wavelength conversion particles with respect to the total solid 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 light 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 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. When the content of the polymerizable compound is 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 cationic polymerizable compound, the above content means the total content of the radical polymerizable compound and the cationic polymerizable compound. To do.

<< Light wavelength conversion particle >>
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 is omitted here.

<< Polymerizable compound and polymerization initiator >>
Since the polymerizable compound and the polymerization initiator are the same as the polymerizable compound and the polymerization initiator described in the resin particle 2, the description thereof is omitted here. In addition, when forming the light source mentioned later using a light wavelength conversion particle containing composition, the polymerizable compound in a light wavelength conversion particle containing composition is an epoxy compound from a viewpoint of sealing the light-emitting body in a light source. And 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 light that has entered a light wavelength conversion layer or a light wavelength conversion unit described later.

  The average particle diameter of the light-scattering particles is, for example, preferably from 0.1 μm to 10 μm, and more preferably from 0.3 μm to 5 μm. If the average particle diameter 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. In order to obtain sufficient light scattering properties, It is necessary to increase the amount of addition. On the other hand, if the average particle diameter of the light-scattering particles exceeds 10 μm, the number of light-scattering particles is reduced even if the addition amount (% by mass) is the same, so that the number of scattering points is reduced 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 luminance change rate before and after the heat resistance test can be reduced, and light Inorganic particles are preferable because incident light on the wavelength conversion sheet can be suitably scattered, and light wavelength conversion efficiency for the incident light can be suitably 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-containing materials 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. Since these inorganic particles can increase the difference in refractive index with 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 by the light wavelength conversion sheet 10 can be improved more suitably, 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 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 light scattering effect can be sufficiently obtained, and by setting the content of the light scattering particles to 50% by mass or less, Mie scattering is reduced. Since it easily occurs, the light scattering effect can be sufficiently obtained, and further, the deterioration of workability can be suppressed.

<<< Light wavelength conversion member >>>
A light wavelength conversion member contains the hardened | cured material of the said 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. 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 near 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, converts the wavelength of some of the incident light to other wavelengths, and another part of the incident light and It is a sheet that emits light whose wavelength has been converted. The light wavelength conversion sheet 10 shown in FIG. 3 includes a light wavelength conversion layer 11, light transmissive substrates 12 and 13 provided on both surfaces of the light wavelength conversion layer 11, and light in the light transmissive substrates 12 and 13. Light diffusion layers 14 and 15 are 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 10 </ b> A and 10 </ b> B of the light wavelength conversion sheet 10. The light wavelength conversion sheet 10 includes the light transmissive substrates 12 and 13 but does not include the barrier layer, and thus does not include the barrier film including the light transmissive substrate and the barrier layer. The light wavelength conversion sheet 10 has a structure of a light diffusion layer 14 / light transmissive substrate 12 / light wavelength conversion layer 11 / light transmissive substrate 13 / light diffusion layer 15; If it has, the structure of a light wavelength conversion sheet will not be specifically limited.

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

In the light wavelength conversion sheet 10, since the heat wavelength conversion particles 1 provide excellent heat resistance and heat and moisture resistance, the water vapor transmission rate (WVTR: Water Vapor Transmission Rate) at 40 ° C. and a relative humidity of 90% is obtained throughout the sheet. May be 0.1 g / (m ² · 24 h) or more. The water vapor transmission rate 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 the conventional light wavelength conversion sheet is formed with a barrier film, 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 is Moisture permeates more easily than conventional light wavelength conversion sheets. 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 transmission rate is the water vapor transmission rate of the entire light wavelength conversion sheet including the optical member.

In the light wavelength conversion sheet 10, excellent heat resistance and heat-and-moisture resistance are obtained by the light wavelength conversion particles 1, so that the entire sheet has an oxygen transmission rate (OTR: Oxygen Transmission Rate) at 23 ° C. and a relative humidity of 90%. It may be 0.1 cm ³ / (m ² · 24 h · atm) or more. The light wavelength conversion sheet 10 may satisfy the water vapor transmission rate and the oxygen transmission rate 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 the conventional light wavelength conversion sheet is formed with a barrier film, the light wavelength conversion sheet 10 has a higher oxygen transmittance than the conventional light wavelength conversion sheet, that is, the light wavelength conversion sheet 10 is Compared with the conventional light wavelength conversion sheet, not only moisture 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.

In the light wavelength conversion sheet 10, the water vapor transmission rate at 40 ° C. and a relative humidity of 90% may be 1 g / (m ² · 24 h) or more, and in the light wavelength conversion sheet 10 at 23 ° C. and a relative humidity of 90%. May have an oxygen permeability of 1 cm ³ / (m ² · 24 h · atm) or more.

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

  The thickness of the light wavelength conversion sheet 10 is obtained 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 locations, and the average value of the thicknesses at the 20 locations is measured. Among these, considering that the film thickness of the light 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. 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.

<< Light wavelength conversion layer >>
The light wavelength conversion layer 11 includes light wavelength conversion particles 1 and a binder resin 16 that is a cured product of a polymerizable compound. The light wavelength conversion layer 11 shown in FIG. 3 further includes light scattering particles 17. By including the light scattering particles 17, the light wavelength conversion efficiency can be improved. The light wavelength conversion particles 1 included in the light wavelength conversion layer 11 are the same as the light wavelength conversion particles 1 described in the column of the light wavelength conversion particles, and the light scattering particles included in the light wavelength conversion layer 11. Since 17 is the same as the light-scattering particles described in the column of the light wavelength conversion-containing particle composition, the description thereof is 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 the specific element to 0.5% by mass or more, deterioration of the quantum dots can be further suppressed. The content of the 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 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%. % Or less is more preferable, and it is further more preferable that it is 10 mass% or less. If the content of the specific element exceeds 20% by mass, sufficient curing may not be performed during the formation of the light wavelength conversion layer.

  The film thickness of the light wavelength conversion layer 11 is preferably 10 μm or more and 200 μm or less. If the average thickness of the light wavelength conversion layer 11 is within this range, it is suitable for reducing the weight and thickness of the backlight device. The film thickness of the light wavelength conversion layer 11 is obtained by photographing a cross section of the light wavelength conversion layer 11 using a scanning electron microscope (SEM), and measuring the film thickness of the light wavelength conversion layer 11 in 20 positions in the image of the cross section. , And the average value of the film thickness at the 20 locations. The upper limit of the average film thickness of the light 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, since the same compound as the polymerizable compound described in the column of the light wavelength conversion particle-containing composition can be used, the description is omitted here.

<< light transmissive substrate >>
The thickness of the light-transmitting substrates 12 and 13 is not particularly limited, but is preferably 10 μm or more and 300 μm or less. If the thickness of the light-transmitting substrates 12 and 13 is less than 10 μm, there is a risk of wrinkling or folding during assembly of the light wavelength conversion sheet and handling, and if it exceeds 300 μm, the weight of the display and the thin film There is a risk that it may not be suitable. 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 transmissive base materials 12 and 13 is the cross section of the light transmissive base materials 12 and 13 using a scanning electron microscope (SEM), a transmission electron microscope (TEM), or a scanning transmission electron microscope (STEM). Is measured, and 20 thicknesses of the light-transmitting substrates 12 and 13 are measured in the cross-sectional image to obtain an average value of the film thicknesses at the 20 locations.

  Examples of constituent materials for the light-transmitting substrates 12 and 13 include polyester (for example, polyethylene terephthalate, polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, and polysulfone. , Thermoplastic resins such as polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate, or polyurethane. As a constituent material of the light-transmitting substrates 12 and 13, preferably, polyester (for example, polyethylene terephthalate, polyethylene naphthalate) is used.

<< light diffusion layer >>
The light diffusion layers 14 and 15 have a concavo-convex shape on the surface, and the light that enters and exits the light wavelength conversion sheet 10 can be diffused by the concavo-convex shape. By providing the light diffusion layers 14 and 15, the light wavelength conversion efficiency in the light wavelength conversion sheet 10 can be further increased. The light diffusion layers 14 and 15 contain light scattering particles and a binder resin.

<Light scattering particles>
The light-scattering particles in the light diffusion layers 14 and 15 are mainly for forming a concavo-convex shape on the surfaces of the light diffusion layers 14 and 15 and exhibiting a light-scattering function.

  The average particle diameter of the light scattering particles in the light diffusion 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 diameter 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 light scattering particles added to provide sufficient light diffusibility. Need to be more. On the other hand, when the average particle diameter of the light scattering particles exceeds 30 μm, the light diffusion performance is excellent, but the light transmittance of the light diffusion layer is likely to be greatly 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. 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, a crosslinked acrylic resin is preferably used. Moreover, it does not specifically limit as an inorganic material which comprises the said light-diffusion particle | grains, For example, inorganic oxides, such as a silica, an alumina, a titania, a tin oxide, an antimony dope tin oxide (ATO), a zinc oxide fine particle, etc. are mentioned. Of these, silica and / or alumina is 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, since the same compound as the polymerizable compound described in the column of the coat layer can be used, the description is omitted here.

<< Production Method of Light Wavelength Conversion Sheet >>
The light wavelength conversion sheet 10 can be produced as follows, for example. First, a light diffusing layer composition containing light scattering particles and a polymerizable compound is applied to one surface of the light transmissive substrate 12 and dried to form a coating film of the light diffusing layer composition. . Similarly, a coating film of the composition for light diffusion layer is formed on one surface of the light transmissive substrate 13.

  Subsequently, the coating film of the composition for light diffusion layers is hardened by light irradiation etc. Thereby, the light diffusing layer 14 is formed on one surface of the light transmissive substrate 12, and the light transmissive substrate 12 with the light diffusing layer 14 is formed. Similarly, the light transmissive substrate 13 with the light diffusion layer 15 is formed.

  After the light transmissive substrate 13 with the light diffusion layer 15 is formed, the light wavelength conversion particle-containing composition is formed on the surface of the light transmissive substrate 13 with the light diffusion layer 15 opposite to the surface on the light diffusion layer 15 side. An object is applied and dried to form a coating film of the composition containing light wavelength conversion particles.

  After the coating film of the light wavelength conversion particle-containing composition is formed, the surface opposite to the light diffusion layer 14 side of the light transmissive substrate 12 with the light diffusion layer 14 is the coating film of the light wavelength conversion particle-containing composition. The light-transmitting substrate 12 with the light diffusion layer 14 is disposed on the coating film of the light wavelength conversion particle-containing composition so as to come into contact with the light-transmitting substrate. Thereby, the coating film of the light wavelength conversion particle-containing composition is sandwiched between the light transmissive substrates 12 and 13.

  Next, the coating film of the light wavelength conversion particle-containing composition is heated through the light transmissive substrate 12, or the coating film is irradiated with ionizing radiation to cure the light wavelength conversion particle-containing composition mixture. Thus, the light wavelength conversion layer 11 is formed, and the light wavelength conversion layer 11 is integrated with the light transmissive substrate 12 with the light diffusion layer 14 and the light transmissive substrate 13 with the light diffusion layer 15. Thereby, the optical wavelength conversion sheet 10 shown in FIG. 3 is obtained.

<< Other light wavelength conversion sheet >>
As shown in FIG. 5, the light wavelength conversion sheet may be a light wavelength conversion sheet 20 having only the light wavelength conversion layer 11 (single layer structure). In addition, 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-transmitting substrate 31 that supports the light wavelength conversion layer 11. . By providing the light transmissive substrate 31, the strength of the light wavelength conversion sheet can be increased more than that of the light wavelength conversion sheet 20.

<Light transmissive substrate>
As the light transmissive substrate 31 of the light wavelength conversion sheet 30, the same material as the light transmissive substrates 12, 13 can be used, and the description thereof will be omitted here.

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

<Optical member>
In this specification, the “optical member” means optical properties (for example, polarization, light refraction, light scattering, light reflectivity, light transmission, light absorption, light diffraction, optical rotation, etc.). It is not particularly limited as long as it is a sheet (film) -like or plate-like member having optical characteristics. Examples of the optical member include a lens sheet, an optical plate such as a light guide plate and a light diffusing plate, a reflective polarization separation sheet, and a polarizing plate. When the optical member sheet is provided on both sides of the light wavelength conversion sheet, the optical member may be an optical member having different optical characteristics. In the present 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 transmissive substrate 42 and a lens layer 43 provided on one surface of the light transmissive substrate 42. As shown in FIGS. 7 and 8, the lens layer 43 includes a sheet-like main body 44 and a plurality of unit lenses 45 arranged side by side on the light output side of the main body 44. The light transmissive substrate 42, the lens layer 43, the main body 44, and the unit lens 45 have the same configuration as the light transmissive substrate 111, the lens layer 112, the main body 113, and the unit lens 114 described later. Therefore, the description is omitted here.

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

<< Other light wavelength conversion sheet >>
As shown in FIG. 9, the light wavelength conversion sheet may be a light wavelength conversion sheet 50 including a light wavelength conversion layer 11 and overcoat layers 51 and 52 covering both surfaces of the light wavelength conversion layer 11. In this embodiment, the overcoat layers 51 and 52 are formed on both surfaces 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 need to be formed on both surfaces of the layer 11. In addition, when the overcoat layer is provided only on one surface of the light wavelength conversion layer, a light transmissive substrate 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 further protected from moisture and oxygen, and the light transmissive substrate is 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 in addition to 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 layers having at least one of functions such as anti-blocking property, light diffusion property, antistatic property, and antireflection property, for example. 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 a certain function. Materials may be added.

  The film thicknesses of the overcoat layers 51 and 52 are 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 reducing the thickness of the light wavelength conversion sheet. Is preferred. The film thickness of the overcoat layers 51 and 52 can be measured by the same method as the film thickness of the light 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. For example, the overcoat layers 51 and 52 include an overcoat containing a (meth) acrylate compound, an epoxy compound, a combination of an isocyanate and a polyol, a metal alkoxide, a silicon-containing resin, a water-soluble polymer, or a mixture thereof. It can be formed using a composition for a coat layer. Among these, from the viewpoint of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere, the overcoat layers 61 and 62 are zinc acrylate, a hydrolysis product of alkoxysilane, polyvinyl alcohol, polysilazane, or these. It is preferable to form using the composition for overcoat layers containing a mixture.

In the light wavelength conversion sheets 20, 30, 40, and 50, the water vapor transmission rate at 40 ° C. and a relative humidity of 90% may be 0.1 g / (m ² · 24 h) or more in the entire sheet. In the light wavelength conversion sheets 20, 30, 40, 50, even if the entire sheet has an oxygen permeability of 0.1 cm ³ / (m ² · 24 h · atm) at 23 ° C. and a relative humidity of 90%. Good. The water vapor transmission rate at 40 ° C. and 90% relative humidity in the light wavelength conversion sheets 20, 30, 40, 50 may be 1 g / (m ² · 24 h) or more, and the light wavelength conversion sheets 20, 30, The oxygen permeability at 23 ° C. and 90% relative humidity at 40 and 50 may be 1 cm ³ / (m ² · 24 h · atm) or more.

<< Other light wavelength conversion sheet >>
The light wavelength conversion sheet may be a light wavelength conversion sheet 60 as shown in FIG. In this case, the water vapor transmission rate and the oxygen transmission rate of the light wavelength conversion sheet 60 may not be within the above-described ranges.

  The light wavelength conversion sheet 60 shown in FIG. 10 includes a light wavelength conversion layer 11, barrier films 61 and 62 provided on both surfaces of the light wavelength conversion layer 11, and the light wavelength conversion layer 11 side of the barrier films 61 and 62. Light diffusion layers 13 and 14 provided on the side opposite to the surface are provided. In the light wavelength conversion sheet 60, the surfaces of the light diffusion layers 13 and 14 constitute the surfaces 60 </ b> A and 60 </ b> B of the light wavelength conversion sheet 60.

<Barrier film>
The barrier films 61 and 62 are members for suppressing the permeation of moisture and oxygen and protecting the quantum dots 3 from moisture and oxygen. Here, the “barrier film” in the present specification is a single member and has a water vapor transmission rate of less than 0.1 g / (m ² · 24 h) at 40 ° C. and a relative humidity of 90%, and at 23 ° C. and a relative humidity. A member whose oxygen permeability at 90% is less than 0.1 cm ³ / (m ² · 24 h · atm) is meant. The barrier film includes not only a single layer structure film but also a multilayer structure film. By installing the barrier films 61 and 62 in a state where the light wavelength conversion layer 11 is sandwiched, the heat resistance and heat 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 transmission of moisture and oxygen. Barrier layers 63 and 64 having functions.

The water vapor transmission rate (WVTR) of the barrier films 61 and 62 is 1.0 × 10 ⁻² g / (m ² · 24 h) or less under the conditions of 40 ° C. and 90% relative humidity. 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).

The oxygen transmission rate (OTR: Oxygen Transmission Rate) of the barrier films 61 and 62 is 1.0 × 10 ⁻² cm ³ / (m ² · 24 h · atm) or less at 23 ° C. and a relative humidity of 90%. More preferably it is. 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 vapor deposition layer having a function of suppressing permeation of moisture and oxygen. A vapor deposition layer is a layer formed by vapor deposition methods, such as physical vapor deposition (PVD) methods, such as sputtering method and an ion plating method, and chemical vapor deposition (CVD) method, for example. A vapor deposition layer has the advantage that barrier property can be improved.

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

  Although the film thickness of a vapor deposition layer is not specifically limited, It is preferable that they are 0.01 micrometer or more and 1 micrometer or less. If the thickness of the deposited layer is less than 0.01 μm, the barrier performance of the deposited layer may be insufficient, and if it exceeds 1 μm, the barrier performance may be easily deteriorated due to cracks in the deposited layer. is there. The minimum with more preferable thickness of a vapor deposition layer is 0.03 micrometer or more, and a more preferable upper limit is 0.5 micrometer or less.

  The film thickness of the vapor deposition layer is obtained by photographing a cross section of the light wavelength conversion sheet 60 using a scanning electron microscope (SEM), measuring the film thickness of the vapor deposition film at 20 positions in the image of the cross section, and measuring the film at the 20 positions. Use the average thickness. Moreover, a single layer may be sufficient as a vapor deposition layer, and what laminated | stacked the several layer may be sufficient as it. When a plurality of vapor deposition layers are laminated, each layer constituting the vapor deposition layer may be directly laminated or bonded.

  The light 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 in a backlight device and an image display device will be described. 11 is a schematic configuration diagram of an image display device including a backlight device according to this embodiment, FIG. 12 is a perspective view of the lens sheet shown in FIG. 11, and FIG. It is sectional drawing along the II line. 14 and 16 are schematic configuration diagrams of another backlight device according to the present embodiment, FIG. 15 is a schematic configuration diagram of a light source shown in FIG. 14, and FIG. 17 is an optical plate shown in FIG. It is an enlarged view near the light incident surface.

<<< Image display device >>>
An image display device 80 shown in FIG. 11 includes a backlight device 90 and a display panel 130 disposed on the light output 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 a display surface 80A.

<< Display panel >>
A display panel 130 shown in FIG. 11 is a liquid crystal display panel, and is provided between a polarizing plate 131 disposed on the light incident side, a polarizing plate 132 disposed on the light output side, and between the polarizing plate 131 and the polarizing plate 132. The liquid crystal cell 133 is provided.

<< Backlight device >>
A 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 disposed on the side of the light source 100, and a light output side of the optical plate 105. The light wavelength conversion sheet 10 disposed on the lens, the lens sheet 110 disposed on the light output side of the light wavelength conversion sheet 10, the lens sheet 115 disposed on the light output side of the lens sheet 110, and the light output side of the lens sheet 115. The reflection-type polarization separation sheet 120 disposed and a reflection sheet 125 disposed on the side opposite to the light output side of the optical plate 105 are provided. The backlight device 90 includes the optical plate 105, the lens sheets 110 and 115, the reflective polarization separation sheet 120, and the reflective sheet 125, but these sheets and the like may not be provided. In the present specification, the “light exit side” means a side from which light is emitted from each member in the direction of exiting the backlight device. The backlight device incorporating the light wavelength conversion sheet 10 is not limited to the edge light type, but may be a direct type backlight device.

  The surface on the optical plate 105 side in the light wavelength conversion sheet 10 is a surface 10A (light incident surface), and the surface on the lens sheet 110 side in the light wavelength conversion sheet 10 is a surface 10B (light exit 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 light emitting diode (LED) or an incandescent bulb. In the present embodiment, the light source 100 is composed of a large number of point-like light emitters, specifically, a large number of light emitting diodes (LEDs) arranged in a line on the light incident surface 95C side to be described later of the optical plate 105. ,It is configured.

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

<Optical plate>
The optical plate 105 as the light guide plate is formed in a square shape in plan view. The optical plate 105 extends between a light exit surface 105A formed by one main surface on the display panel 130 side, a back surface 105B composed of the other main surface facing the light output surface 105A, and the light output surface 105A and the back surface 105B. And have side faces. Of the side surfaces, the side surface on the light source 100 side is a light incident surface 105 </ b> C that receives light from the light source 100. Light entering the optical plate 105 from the light incident surface 105C is guided through the optical plate in a direction (light guide direction) connecting the light incident surface 105C and the opposite surface opposite to the light incident surface 105C. The light is 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 it from the light output side. In the present embodiment, as shown in FIG. 12, the function of concentratingly improving the brightness in the front direction by changing the traveling direction of the light L3 having a large incident angle and emitting it from the light exit side (condensing function). In addition, it has a function (retroreflection function) of reflecting the 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 transmissive substrate 111 and a lens layer 112 provided on one surface of the light transmissive substrate 111.

(Light transmissive substrate)
Since the light transmissive substrate 111 is the same as the light transmissive substrates 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-like main body 113 and a plurality of unit lenses 114 arranged side by side on the light output 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, the unit lenses 114 are arranged on the light output side surface 113 </ b> A of the main body 113 without leaving a gap. Therefore, the light exit surfaces 110B and 115B of the lens sheets 110 and 115 are formed by lens surfaces. On the other hand, as shown in FIG. 13, the main body 113 has a smooth surface that forms the light incident side surface of the lens layer 112 as the light incident side surface 113B that faces the light outgoing side surface 113A.

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

  The unit lens 114 may have a triangular prism shape, a wavy shape, or a bowl shape such as a hemisphere. Specifically, examples of the unit lens include a unit prism, a unit cylindrical lens, and a unit microlens. 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 lenses 114 of the lens sheet 110 and the arrangement direction of the unit lenses 114 of the lens sheet 115 intersect, and more specifically, are orthogonal to each other.

<Reflection-type polarized light separation sheet>
The reflection-type polarization separation sheet 120 transmits only a first linearly polarized light component (for example, P-polarized light) out of 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 a polarized light component (for example, S-polarized light) without absorbing it. In the state where the second linearly polarized light component reflected by the reflective polarization separation sheet 120 is reflected again and depolarized (including both the first linearly polarized light component and the second linearly polarized light component), The light again enters the reflective polarization separation sheet 120.

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

<Reflection sheet>
The reflection sheet 125 has a function of reflecting light leaking from the back surface 105 </ b> B of the optical plate 105 and making it enter the optical plate 105 again. The reflection sheet 125 includes a white scattering reflection sheet, a sheet made of a material having a high reflectance such as metal, a sheet containing a thin film (for example, a metal thin film) made of a material having a high reflectance as a surface layer, and the like. obtain.

<< Other backlight devices >>
Although the backlight device 90 shown in FIG. 11 includes the light wavelength conversion sheet 10, the structure of the backlight device is not particularly limited as long as the light wavelength conversion member is included. 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 one form of a light wavelength conversion member.

  As shown in FIG. 15, the light source 160 includes a substrate 161, a reflective member 162 having an opening 162 </ b> A disposed on the substrate 161, and a light emission disposed on the substrate 161 and in the opening 162 </ b> A of the reflective member 162. A light emitter 163 such as a diode, and an optical wavelength converter 164 filled in the opening 162A of the reflecting member 162 so as to cover the light emitter 163 are provided.

  The optical wavelength conversion unit 164 is different from the optical wavelength conversion layer 11 only in shape and location, and the configuration and physical properties of the optical wavelength conversion unit 164 are the same as those of the optical wavelength conversion layer 11. The light wavelength conversion part 164 is a cured product of a light wavelength conversion particle-containing composition containing the light wavelength conversion particles 1 and a polysiloxane compound having an epoxy compound or a silanol group and / or an alkoxysilyl group as a polymerizable compound. It is preferable. The light wavelength conversion part 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. In addition, when using the light source 160 which has the light wavelength conversion part 164, if the light wavelength conversion part 164 is arrange | positioned so that the light-emitting body 163 may be covered, a structure will not be specifically limited.

<< 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 disposed between the light source 100 and the optical plate 105 instead of the light wavelength conversion sheet 10. Yes. 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 incident surface 105C of the optical plate 105 as shown in FIG. The light 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, and therefore the description thereof is omitted here. And

  According to this embodiment, since 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, as in the light wavelength conversion sheets 10, 20, 30, 40, 50 The barrier film can be omitted. Thereby, while being able to simplify the process of a light wavelength conversion sheet, it becomes easy to improve quality, and thickness reduction of a light wavelength conversion sheet can be achieved.

  In a light wavelength conversion sheet provided with a barrier film, when a heat resistance test or a moist heat resistance test is performed, point-like defects such as pinholes and cracks are likely to occur in the barrier film. When a defect part is generated in the barrier film, moisture or oxygen enters from the defect part, and some quantum dots are deteriorated, and there is a possibility that a part (luminance defect) in which the luminance is reduced in a dot shape in the light wavelength conversion sheet is generated. . This dot-like luminance defect is more visible than the case where the quantum dots deteriorate as a whole and the luminance decreases uniformly. On the other hand, according to the present embodiment, since the deterioration of the quantum dots 3 can be suppressed by the resin particles 2 containing at least one of the specific element and the carboxylic acid, a defect portion is generated in the barrier films 71 and 72, for example. Thus, even if moisture or oxygen enters from this defect portion, the point-like luminance defect can be suppressed.

  According to this embodiment, since 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, in the light 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 light wavelength conversion sheet 40, the light wavelength conversion layer 11 and the optical member 41 are integrated. Therefore, the light wavelength conversion sheet 40 is simplified and thin compared to the case where the light wavelength conversion sheet and the optical member are separately disposed. A backlight device can be obtained. That is, when the light wavelength conversion sheet and the optical member are separately arranged, there is an air interface between the light wavelength conversion sheet and the optical member, so that a relatively large gap is formed in the backlight device. Cost. On the other hand, in this 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. Thereby, a simplified thin backlight device can be obtained.

  Light emitters such as light emitting diodes also generate heat during light emission. For this reason, normally, when the light wavelength conversion unit is incorporated in the light source or when the light wavelength conversion unit is disposed at a position close to the light source, the light wavelength conversion unit is covered to suppress the deterioration of the quantum dots. A barrier member is required. On the other hand, in the present embodiment, the heat resistance and the heat and moisture resistance in the light wavelength conversion unit 164 and the light wavelength conversion layer 180 by the binder resin 3 of the light wavelength conversion particle 1 in the light wavelength conversion unit 164 and the light wavelength conversion layer 180. Therefore, the deterioration of the quantum dots 4 can be suppressed without covering the light wavelength conversion part 164 and the light wavelength conversion layer 180 with a barrier member.

  In order to describe the present invention in detail, examples will be described 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 aqueous polyvinyl alcohol solution and 267.55 parts by mass of ion-exchanged water were added to a 500 ml separable flask, and the mixture was stirred with a stir bar so that the concentration of polyvinyl alcohol relative to water was 1.52. A mass% polyvinyl alcohol aqueous solution A was obtained. Using a B-type viscometer (product name “TVB-10”, manufactured by Toki Sangyo Co., Ltd.), when the viscosity of the obtained aqueous polyvinyl alcohol solution A at 25 ° C. was measured, the viscosity was 0.03 Pa · s. It was. In addition, the viscosity in 25 degreeC of polyvinyl alcohol aqueous solution BF mentioned later was also measured using the same viscometer as the above.

  On the other hand, in a disposable cup, green light emitting quantum dots (product name “CdSe / ZnS 530”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm) 1.0 part by mass, red Luminescent 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 tricyclodecane dimethanol diacrylate (product) A mixture with 50 parts by mass of “A-DCP” (manufactured by Shin-Nakamura Chemical Co., Ltd.) was charged. 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 , 2′-azobis (2,4-dimethylvaleronitrile), manufactured by Tokyo Chemical Industry Co., Ltd. (1.0 part by mass) was added and stirred to obtain mixture 1 for light wavelength conversion particles.

  And the mixture 1 for light wavelength conversion particles was thrown into the polyvinyl alcohol aqueous solution A within 10 minutes after throwing in tetraethylene glycol bis (3-mercaptopropionate). Then, using a homogenizer, the mixture was stirred for 10 minutes at a stirring speed of 7000 rpm and suspended. In addition, stirring was performed in the state which enclosed the circumference | surroundings of the separable flask with the wrap so that the contents of the separable flask might not scatter.

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

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

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

<Example 4>
(Light wavelength conversion particle 4)
Instead of the polyvinyl alcohol aqueous solution A, a light wavelength conversion particle 4 was obtained by the same procedure as the light wavelength conversion particle 1 except that a polyvinyl alcohol aqueous solution D having a concentration of polyvinyl alcohol with respect to water of 18% by mass was used. The polyvinyl alcohol aqueous solution D was obtained by charging 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 at 25 degreeC of the obtained polyvinyl alcohol aqueous solution D was measured, the viscosity was 6 Pa * s.

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

<Example 6>
(Light wavelength conversion particle 6)
A procedure similar to that for the light wavelength conversion particle 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). The 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 particles 7 were obtained by the same procedure as that for the light wavelength conversion particles 1.

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

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

<Comparative Example 3>
(Light wavelength conversion particle 10)
Instead of the polyvinyl alcohol aqueous solution A, a light wavelength conversion particle 10 was obtained by the same procedure as the light wavelength conversion particle 1 except that a polyvinyl alcohol aqueous solution F having a concentration of polyvinyl alcohol with respect to water of 20% by mass was used. 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 with a stirring rod. When the viscosity at 25 degreeC of the obtained polyvinyl alcohol aqueous solution F was measured, the viscosity was 12 Pa * s.

<< Preparation of composition containing light wavelength conversion particles >>
Each component was mix | blended so that it might become a composition shown below, and the light wavelength conversion particle containing composition was obtained.
<Example 8>
(Light wavelength conversion particle-containing composition 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-hydroxycyclohexyl phenyl ketone, product name "Irgacure ( Registered trademark) 184 ", manufactured by BASF Japan Ltd.): 1 part by mass

<Examples 9 to 14 and Comparative Examples 4 to 6>
(Light wavelength conversion particle-containing composition 2 to 10)
In the light wavelength conversion particle-containing compositions 2 to 10, the same composition as 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. It was. The 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 mix | blended so that it might become a composition shown below, and the composition 1 for light diffusion layers was obtained.
(Composition 1 for light diffusion layer)
Pentaerythritol triacrylate: 99 parts by mass Light scattering particles (cross-linked polystyrene resin particles, product name “SBX-4”, manufactured by Sekisui Plastics Co., Ltd., average particle size 4 μm): 158 parts by mass Radical polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name “Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.): 1 part by mass / solvent (methyl isobutyl ketone: cyclohexanone = 1: 1 (mass ratio)): 170 parts by mass

<Preparation of composition for overcoat layer>
Each component was mix | blended so that it might become the composition shown below, and the composition 1 for overcoat layers was obtained.
(Composition 1 for overcoat layer)
-Zinc acrylate (product name "ZN-DA" manufactured by Nippon Shokubai Co., Ltd.): 25 parts by mass-Mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (product name "Aronix (registered trademark) M-403", Tojo (Manufactured by Synthesis Co., Ltd.): 5 parts by mass, methanol: 70 parts by mass, radical polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name “Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.): 1 part by mass

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

Subsequently, the light wavelength conversion particle containing composition 1 was apply | coated to the surface on the opposite side to the surface by the side of the light-diffusion layer in one PET base material with a light-diffusion layer, and it was made to dry at 80 degreeC, and the coating film was formed. And the other PET base material with a light-diffusion layer was laminated | stacked on the coating film so that the surface on the opposite side to the surface at the side of the light-diffusion layer in the other PET base material with a light-diffusion layer may contact | connect a coating film. In this state, the coating film is cured by irradiating ultraviolet rays so that the integrated light quantity becomes 500 mJ / cm ² to form a light wavelength conversion layer with a film thickness of 100 μm, and the light wavelength conversion layer and two light beams A PET substrate with a diffusion layer was integrated. As a result, an optical wavelength conversion sheet according to Example 15 was obtained.

<Examples 16 to 21 and Comparative Examples 7 to 9>
In Examples 16-21 and Comparative Examples 7-9, it is the same as that of Example 15 except having used each light wavelength conversion particle containing composition shown in Table 3 instead of the light wavelength conversion particle containing composition 1. Thus, a light wavelength conversion sheet was produced.

<Example 22>
The light wavelength conversion particle-containing composition 1 was applied to one surface of a 50 μm-thick polyethylene terephthalate (PET) substrate (product name “Lumirror T60”, manufactured by Toray Industries, Inc.) to form a coating film. And it heated at 100 degreeC, the coating film was hardened, and the light wavelength conversion layer was formed. And the composition 1 for overcoat layers was apply | coated to the surface on the opposite side to the surface by the side of the PET base material of a light wavelength conversion layer, and the coating film was formed. And the ultraviolet-ray was irradiated so that an integrated light quantity might be set to 500 mJ / cm < ² >, the coating film was hardened, and the overcoat layer with a film thickness of 5 micrometers was obtained. Subsequently, after peeling off the PET base material, the overcoat layer composition 1 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. And the ultraviolet-ray was irradiated so that an integrated light quantity might be set to 500 mJ / cm < ² >, the coating film was hardened, and the overcoat layer with a film thickness of 5 micrometers was obtained. This obtained the light wavelength conversion sheet which consists of a light wavelength conversion layer and the overcoat layer formed in both surfaces of the light wavelength conversion layer.

<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 was uniformly applied to one surface of a polyethylene terephthalate (PET) base material (product name “Lumirror T60”, manufactured by Toray Industries, Inc.) having a thickness of 100 μm. A coating film was formed to form a prism sheet laminate. Then, the prism sheet laminate is traveled at a running speed so that the coating layer of the lens layer composition is on the molding die side and has a concave portion having a reverse shape with respect to the shape of the desired unit prism. The shape of the unit prism is formed on the coating film of the prism layer composition by a molding die by supplying at 20 m / min, and light such as ultraviolet rays is applied to the coating film of the prism layer composition through the PET substrate. Irradiation was performed to cure the coating film of the prism layer composition. Finally, the cured coating film of the prism layer composition was peeled off from the molding die 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 layer has a sheet-like main body, and is arranged side by side on the main body. Each prism layer extends in a direction intersecting the arrangement direction, has an apex angle of 90 °, a width of 47 μm, and a height. Had a plurality of triangular prism unit prisms.

  Next, the optical wavelength conversion particle-containing composition 1 was applied to the surface of the prism sheet opposite to the surface on the prism layer side of the PET base material to form a coating film. And the light wavelength conversion layer whose film thickness integrated with the prism sheet was 100 micrometers was formed by heating at 100 degreeC and hardening | curing a coating film. As a result, an 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 produced by the following method. Polyethylene terephthalate as a light-transmitting substrate having a size of 7 inches and a thickness of 50 μm is generated in a chamber by applying a high-frequency power with a frequency of 13.56 MHz and a power of 5 kW to an electrode in a high-frequency sputtering apparatus. A silica vapor deposition layer having a thickness of 50 nm and a refractive index of 1.46 made of a target material (silica) was formed on one side of a (PET) substrate (product name “Lumirror T60”, manufactured by Toray Industries, Inc.). Thus, two barrier films each having a silica vapor deposition layer formed on one surface of the PET substrate were formed.

Subsequently, the said composition 1 for light diffusion layers was apply | coated to the surface on the opposite side to the surface at the side of a silica vapor deposition layer in both barrier films, and the coating film was formed. Next, the solvent in the coating film was evaporated by allowing the formed coating film to dry by passing dry air at 80 ° C. for 30 seconds. Then, the light diffusion layer with a film thickness of 10 μm was formed by irradiating with ultraviolet rays so that the integrated light amount was 500 mJ / cm ² to cure the coating film, thereby forming a barrier film with a light diffusion layer.

  Subsequently, the light wavelength conversion particle containing composition 1 was apply | coated to the silica vapor deposition layer side of one barrier film with a light-diffusion layer, and the coating film was formed. And the other barrier film with a light-diffusion layer was laminated | stacked so that the silica vapor deposition layer might contact | connect the surface of the silica vapor deposition layer of the barrier film with a light-diffusion layer in a coating film. In this state, by heating at 100 ° C. to cure the coating film, a light wavelength conversion layer having a thickness of 100 μm adhered to both barrier films with a light diffusion layer was formed. As a result, an 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 light wavelength conversion particles 1 to 10 obtained in Examples 1 to 7 and Comparative Examples 1 to 3, and light wavelength conversion particle-containing compositions 1 to 10 according to Examples 8 to 14 and Comparative Examples 4 to 6 While measuring the average particle diameter of the conversion particles 1 to 10 respectively, the standard deviation of the particle size distribution of the light wavelength conversion particles was determined. Specifically, the average particle diameter of the light wavelength conversion particles is obtained by measuring the particle diameter of 20 light wavelength conversion particles in the observation of the light wavelength conversion particles by a scanning electron microscope (SEM), and calculating the average value. The standard deviation of the particle size distribution of the light wavelength conversion particles was calculated based on the particle size distribution of the light wavelength conversion particles measured when determining the average particle size. In Tables 1 and 2, “−” in the column of average particle diameter and standard deviation means that the light wavelength conversion particles are too large to be measured.

<Confirmation of specific element and carboxylic acid in resin particle in light wavelength conversion particle>
Light wavelengths in light wavelength conversion particles 1 to 10 obtained in Examples 1 to 7 and Comparative Examples 1 to 3, and light wavelength conversion particle-containing compositions 1 to 10 according to Examples 8 to 14 and Comparative Examples 4 to 6 In conversion particle | grains 1-10, it was each confirmed whether the said specific element or carboxylic acid was detected from the resin particle of light wavelength conversion particle | grains. 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. And in the light wavelength conversion particle containing compositions 1-10 which concern on the light wavelength conversion particles 1-10 obtained in Examples 1-7 and Comparative Examples 1-3 and Examples 8-14 and Comparative Examples 4-6. In the light wavelength conversion particles 1 to 10, an energy dispersive X-ray analyzer (product name “JEM-2800” (100 mm ² silicon drift detector (SDD) mounted), manufactured by JEOL Ltd.) is used, and an acceleration voltage of 100 kV and Whether at least one of elemental sulfur, elemental phosphorus, and elemental nitrogen is detected on the surface of the resin particle at an interval of 3 nm or more from the surface of the quantum dot shell or at an arbitrary position under the measurement time of 30 seconds I confirmed it. In addition, using an infrared microscope (product name “Nicolet iN10”, manufactured by Thermo Fisher Scientific), carboxylic acid can be detected at any position on the surface of the resin particle or inside the resin particle 3 nm or more away from the surface of the quantum dot shell. Confirmed whether or not. The confirmation criteria were as follows.
◯: Any of elemental sulfur, elemental phosphorus, elemental nitrogen and carboxylic acid was detected.
X: Neither sulfur element, phosphorus element, nitrogen element nor carboxylic acid was detected.

<Dispersibility evaluation of light wavelength conversion particles>
The light wavelength conversion particle-containing compositions 1 to 10 according to Examples 8 to 14 and Comparative Examples 4 to 6 were observed to evaluate the dispersibility of the light wavelength conversion particles 1 to 10. The evaluation criteria were as follows.
○: Aggregation of the light wavelength conversion particles was not observed, or some aggregation was observed, but it was at a level causing no practical problem.
X: Many aggregations of the light wavelength conversion particles were confirmed.

<Specific element content measurement>
Light wavelengths in light wavelength conversion particles 1 to 10 obtained in Examples 1 to 7 and Comparative Examples 1 to 3, and light wavelength conversion particle-containing compositions 1 to 10 according to Examples 8 to 14 and Comparative Examples 4 to 6 In the conversion particles 1 to 10, the content of a specific element contained in the light wavelength conversion 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 determined by measuring the content of the specific element in each of the 20 light wavelength conversion particles, and taking the average value thereof.

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

<Measurement of luminance maintenance ratio 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 is performed in which the light wavelength conversion sheet is left in an environment of 80 ° C. for 500 hours before the heat resistance test in the light wavelength conversion sheet. The maintenance rate of the luminance after the heat resistance test with respect to the luminance was investigated. Specifically, first, a backlight device of Kindle Fire (registered trademark) HDX7 was prepared, and a light wavelength conversion sheet before a heat resistance test was incorporated into the 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 disposed so that the blue light emitting diode side is the light incident surface, and Examples 15 to 22, 24 are provided on the light exit surface of the light guide plate. And the light wavelength conversion sheet | seat which concerns on Comparative Examples 7-10, 12, the 1st prism sheet, and the 2nd prism sheet were arrange | positioned in this order, and the backlight apparatus was obtained. Note that the second prism sheet was disposed 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 incident surface, and the prism surface of the prism sheet is on the light output side of the light guide plate. And the light wavelength conversion sheet | seat which concerns on the comparative example 11, and the 2nd prism sheet | seat are arrange | positioned in this order, and the backlight apparatus was obtained. 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 sheets according to Example 23 and Comparative Example 11. In this way, a backlight device in which the light wavelength conversion sheets according to Example 23 and Comparative Example 11 were incorporated was obtained.

  Then, the blue light emitting diode of the backlight device incorporating the light wavelength conversion sheet is turned on, the blue light is irradiated on 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 luminance of light emitted from the light emitting surface (surface of the second prism sheet) is measured from the thickness direction of the light wavelength conversion sheet using a spectral radiance meter (product name “CS2000”, manufactured by Konica Minolta). The measurement was performed at an angle of 1 °.

  Subsequently, the light wavelength conversion sheet before the heat resistance test was removed from the backlight device, and a heat resistance test was performed on the light wavelength conversion sheet by leaving the light wavelength conversion sheet in an environment of 80 ° C. for 500 hours. And the light wavelength conversion sheet | seat after a heat resistance test was integrated in the said backlight apparatus similarly to the above. In this state, as described above, blue light is irradiated on one surface of the light wavelength conversion sheet, and the light emitting surface of the backlight device (the surface of the second prism sheet) is passed through the other surface of the light wavelength conversion sheet. ) Was measured from the thickness direction of the light wavelength conversion sheet using a spectral radiance meter (product name “CS2000”, manufactured by Konica Minolta) at a measurement angle of 1 °.

From these measured luminances, the maintenance ratio of the luminance after the heat resistance test with respect to the luminance before the heat resistance test was determined. The luminance maintenance factor is A, the luminance maintenance factor is A, the luminance of light emitted from the light emitting surface of the backlight device before the heat resistance test is B, and the luminance of light emitted from the light emitting surface of the backlight device after the heat resistance test. Was determined by the following formula.
A = C / B × 100

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

  Then, the blue light emitting diode of the backlight device incorporating the light wavelength conversion sheet is turned on, the blue light is irradiated on 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 luminance of light emitted from the light emitting surface (surface of the second prism sheet) is measured from the thickness direction of the light wavelength conversion sheet using a spectral radiance meter (product name “CS2000”, manufactured by Konica Minolta). The measurement was performed at an angle of 1 °.

  Next, the light wavelength conversion sheet before the wet heat resistance test is removed from the backlight device, and a heat resistance test is performed on the light wavelength conversion sheet by leaving the light wavelength conversion sheet in an environment of 60 ° C. and 90% relative humidity for 500 hours. It was. And the light wavelength conversion sheet after a heat-and-moisture resistance test was integrated in the said backlight apparatus similarly to the above. In this state, as described above, blue light is irradiated on one surface of the light wavelength conversion sheet, and the light emitting surface of the backlight device (the surface of the second prism sheet) is passed through the other surface of the light wavelength conversion sheet. ) Was measured from the thickness direction of the light wavelength conversion sheet using a spectral radiance meter (product name “CS2000”, manufactured by Konica Minolta) at a measurement angle of 1 °.

From these measured luminances, the maintenance ratio of the luminance after the moist heat resistance test with respect to the luminance before the moist heat resistance test was determined. The luminance maintenance factor is D, the luminance maintenance factor is D, the luminance of light emitted from the light emitting surface of the backlight device before the moisture and heat resistance test is E, and the luminance of light emitted from the light emitting surface of the backlight device after the moisture and heat resistance test. Was determined by the following formula.
D = F / E × 100

<Spot-like luminance defect evaluation>
Using the above-described 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 luminance defect on the light emitting surface at the time of light emission in the backlight device. The presence was visually observed and evaluated. In addition, using the above backlight device incorporating the light wavelength conversion sheet after the wet heat resistance test according to Examples 15 to 24 and Comparative Examples 7 to 12, similarly, the light emitting surface at the time of light emission in the backlight device is pointed The presence or absence of a luminance defect was visually observed and evaluated. The evaluation criteria were as follows.
○: No dot-like luminance defect was confirmed.
Δ: Several point-like luminance defects were confirmed.
X: Many point-like brightness | luminance defects were confirmed.

<Measurement of degradation width of peripheral edge of optical wavelength conversion sheet>
Using the above 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 luminance distribution on the light emitting surface at the time of light emission in the backlight device is expressed as the light wavelength. It measured using the 2D color luminance meter (Product name "UA-200", Topcon Technohouse company make) from the thickness direction of the conversion sheet. Then, from the measured luminance distribution of the light emitting surface, the position of the light emitting surface where the luminance is 80% with respect to the luminance of the central portion of the light emitting surface (luminance 80% position) is obtained, and is closest to the luminance 80% position on the light emitting surface. The shortest distance from the edge to the 80% luminance position was determined. And this shortest distance was calculated | required about 20 places at random, and the average value of these 20 shortest distances was made into the degradation width of the peripheral part of a light wavelength conversion sheet. Further, using the above backlight device incorporating the light wavelength conversion sheet after the moisture and heat resistance test according to Examples 15 to 24 and Comparative Examples 7 to 12, the luminance distribution of the light emitting surface was measured in the same manner, and light emission was performed. The position of the light emitting surface where the luminance is 80% of the luminance at the center of the surface (80% luminance position) is obtained, and the shortest distance from the edge closest to the 80% luminance position on the light emitting surface to the luminance 80% position is obtained. 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 diameter and less variation than the light wavelength conversion particles 9 and 10 according to Comparative Examples 2 and 3. It was. Moreover, 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 conversions according to Comparative Examples 5 and 6. The average particle diameter was smaller and the variation was smaller than the light wavelength conversion particles 9 and 10 contained in the particle-containing compositions 9 and 10. In addition, in the light wavelength conversion particle | grains 10 contained in the light wavelength conversion particle | grains 10 which concern on the comparative example 3, and the light wavelength conversion particle | grain containing composition 10 which concerns on the comparative example 6, it is a gel-like lump because viscosity is too high. It is considered that the particle diameter became too large for this reason.

  Moreover, as can be seen from Table 2, in the light wavelength conversion particle-containing compositions 1 to 7 according to Examples 8 to 14, the light wavelength conversion particle-containing compositions 9 and 10 according to Comparative Examples 5 and 6 are more light. Dispersibility of the wavelength converting particles was excellent.

  Furthermore, as can be seen from Tables 3 and 4, in the light wavelength conversion sheets according to Examples 15 to 23, the light wavelength in which the quantum dots are included in the resin particles containing at least one of the specific element and the carboxylic acid. Since the conversion particles 1 to 7 are used, the resin particles containing the quantum dots are used, but the light wavelength conversion according to Comparative Examples 7, 10, and 11 in which the resin particles do not contain any of the specific element and carboxylic acid. Compared to the sheet, the luminance maintenance rate after the heat resistance test and after the heat and humidity resistance test was high. Further, in the light wavelength conversion sheet according to Example 24, since the light wavelength conversion particles 1 in which the quantum dots are included in the resin particles containing at least one of the specific element and the carboxylic acid are used, the quantum dots are used. Luminance maintenance rate after the heat resistance test and after the heat and humidity resistance test, as compared with the light wavelength conversion sheet according to Comparative Example 12 in which the resin particles included are used but the resin particles do not contain any of the specific element and carboxylic acid Was expensive. This means that the heat wavelength and moist heat resistance of the light wavelength conversion particles 1 to 7 according to Examples 1 to 7 are high, and at least one of the specific element and the carboxylic acid can suppress the deterioration of the quantum dots. Yes.

  In the light wavelength conversion sheets according to Examples 15 to 23 and Comparative Examples 7 to 11, no barrier film was used, and thus no point-like luminance defect was confirmed. Moreover, in the light wavelength conversion sheet | seat which concerns on Example 24, although the barrier film is used, the light wavelength conversion particle | grains 1 in which the quantum dot was included in the resin particle containing at least any one of a specific element and carboxylic acid were used. Since it was used, no dot-like luminance defect was confirmed. On the other hand, although resin particles containing quantum dots are used, in the light wavelength conversion sheet according to Comparative Example 12 in which the resin particles do not contain any of the specific element and carboxylic acid, dot-like luminance defects are confirmed. It 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 quantum dots are encapsulated in resin particles containing at least one of a specific element and a carboxylic acid are used, The deterioration of the part was suppressed. In contrast, in the light wavelength conversion sheet according to Comparative Examples 7, 10, and 11 in which the resin particles contain the quantum dots and the resin particles do not contain any of the specific element and carboxylic acid, Deterioration was confirmed. This is because, even in an environment where the quantum dots are exposed to a large amount of oxygen or water vapor, such as the peripheral portion, if the resin particles contain at least one of a specific element and a carboxylic acid, the deterioration of the quantum dots is suppressed. It means you can do it. Further, in the light wavelength conversion sheet according to Comparative Example 12, deterioration of the central portion was relatively suppressed by the barrier film, but deterioration of the peripheral portion was not suppressed.

  In the optical wavelength conversion particles 1 to 6 contained in the optical wavelength conversion particles 1 to 6 according to Examples 1 to 6 and the optical 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. In contrast, in the light wavelength conversion particles 8 according to Comparative Example 1 and the light wavelength conversion particles 8 included 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 was less than 0.5% by mass. In addition, in the light wavelength conversion particle 8, although the specific element is not contained in the mixture for light wavelength conversion particles used when forming the light wavelength conversion particle 8, the content of the specific element is 0 mass. It is thought that it is because the sulfur component was contained in quantum dot itself that it is not%.

  In the above embodiment, CdSe is used as the core material of the green light emitting quantum dots and the red light emitting quantum dots. However, even when a non-Cd material such as InP or InAs is used as the core material, the same results as in the above embodiments are obtained. was gotten.

DESCRIPTION OF SYMBOLS 1, 5 ... Light wavelength conversion particle 2 ... Resin particle 3 ... Quantum dot 4 ... Coat layer 10, 20, 30, 40, 50, 60 ... Light wavelength conversion sheet 11 ... Light wavelength conversion layer 16 ... Binder resin 17 ... Light scattering Particles 70 ... image display devices 80, 150, 170 ... backlight device

Claims (11)

A method for producing light wavelength conversion particles comprising light transmissive resin particles and quantum dots encapsulated in the resin particles,
A solution containing a suspension stabilizer and having a viscosity at 25 ° C. of 0.02 Pa · s to 10 Pa · s, a quantum dot, a polymerizable compound, a sulfur-containing compound, a phosphorus-containing compound, a nitrogen-containing compound, and a carvone A method for producing light wavelength conversion particles, comprising a step of performing suspension polymerization by mixing one or more compounds selected from the group consisting of acids and a mixture containing a polymerization initiator.   The method for producing light wavelength conversion particles according to claim 1, wherein the suspension stabilizer is a nonionic water-soluble polymer. Light wavelength converting particles,
Including light transmissive 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 encapsulated in the resin particles,
The light wavelength conversion particles have an average particle size of 10 μm or less,
The light wavelength conversion particles according to claim 1, wherein a standard deviation of a particle size distribution of the light wavelength conversion particles is 8 μm or less.   The composition containing light wavelength conversion particle | grains containing the light wavelength conversion particle | grains of Claim 3.   The composition containing light wavelength conversion particles according to claim 4, further comprising a suspension stabilizer.   The composition containing light wavelength conversion particles according to claim 4, further comprising a polymerizable compound.   The light wavelength conversion member containing the hardened | cured material of the light wavelength conversion particle containing composition of Claim 6.   A light wavelength conversion sheet provided with the light wavelength conversion layer which consists of hardened | cured material of the light wavelength conversion particle containing composition of Claim 6. Water vapor transmission rate at 40 ° C. and relative humidity 90% is 0.1 g / (m ² · 24 h) or more and oxygen transmission rate at 23 ° C. and relative humidity 90% is 0.1 cm ³ / (m ² · 24 h · atm 9) The light wavelength conversion sheet according to claim 8, which satisfies at least one of the above. A light source;
A backlight device comprising: the light wavelength conversion member according to claim 7 or the light wavelength conversion sheet according to claim 8 that receives light from the light source.   An image display device comprising the light wavelength conversion member according to claim 7, the light wavelength conversion sheet according to claim 8, or the backlight device according to claim 10.

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