JP6903924B2 - Light wavelength conversion sheet, backlight device, image display device, light wavelength conversion composition, and light wavelength conversion member - Google Patents

Description

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

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

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

Japanese Unexamined Patent Publication No. 2015-11518

In the optical wavelength conversion sheet, quantum dots are deteriorated by moisture and oxygen, and the luminous efficiency may decrease. Therefore, barrier members for suppressing the transmission of moisture and oxygen are provided on both sides of the optical wavelength conversion layer. It is provided. Since the barrier member is provided so as to sandwich the light wavelength conversion layer, the conventional light wavelength conversion sheet has a structure in which the barrier member, the light wavelength conversion layer, and the barrier member are laminated in this order.

On the other hand, in a backlight device, as a reliability test usually performed, a heat resistance test of leaving in an environment of 80 ° C. for 500 hours, a moisture resistance test of leaving in an environment of 60 ° C. and a relative humidity of 90% for 500 hours, And there is a light resistance test that irradiates light for 200 hours in an environment of 42 ° C and 50% relative humidity, and it is desirable that each member of the backlight device meets the criteria of heat resistance test, moisture heat resistance test and light resistance test. ing. However, when a heat resistance test or the like is performed on an optical wavelength conversion sheet having the above structure, there is a problem that the quantum dots are deteriorated and the brightness is lowered.

Further, in an optical wavelength conversion sheet provided with a barrier member, pinholes and cracks are likely to occur in the barrier member when a heat resistance test or the like is performed. When pinholes or cracks occur in the barrier member, moisture or oxygen may enter from there, and some quantum dots may deteriorate, resulting in spot-like reduced brightness (luminance defects) in the optical wavelength conversion sheet. There is. This punctate luminance defect is more easily visible than in the case where the quantum dots are deteriorated as a whole and the luminance is uniformly lowered. Further, at present, it is desired to further reduce the thickness and manufacturing cost of the optical wavelength conversion sheet. For these reasons, it is currently being considered not to use a barrier member. However, since the current optical wavelength conversion layer does not have a function of protecting the quantum dots from moisture and oxygen, the quantum dots deteriorate unless the barrier member is used.

The present invention has been made to solve the above problems. That is, an optical wavelength conversion sheet having excellent heat resistance, moisture heat resistance, and light resistance, the barrier member can be omitted, or even when the barrier member is used, the punctate luminance defect can be suppressed, such light. It is an object of the present invention to provide a backlight device and an image display device provided with a wavelength conversion sheet. Another object of the present invention is to provide a light wavelength conversion composition and a light wavelength conversion member having excellent heat resistance, moisture heat resistance and light resistance.

As a result of diligent research on the above-mentioned problems, the present inventors have found that the light wavelength conversion composition is excellent by including one or more compounds selected from the group consisting of phenol-based compounds and amine-based compounds. When a light wavelength conversion composition having heat resistance, moisture heat resistance and light resistance and a light wavelength conversion member such as a light wavelength conversion layer are obtained, and when a light wavelength conversion sheet is formed using this light wavelength conversion member, It has been found that it has excellent heat resistance, moisture heat resistance and light resistance, and that the barrier member can be omitted, or even when the barrier member is used, the punctate brightness defect can be suppressed. The present invention has been completed based on such findings.

According to one aspect of the present invention, a light wavelength conversion sheet including at least a light wavelength conversion layer, wherein the light wavelength conversion layer is composed of a binder resin, quantum dots, a phenol-based compound, and an amine-based compound. The light incident on one surface of the optical wavelength conversion sheet when one surface of the optical wavelength conversion sheet is irradiated with light whose wavelength can be converted by the quantum dots, which contains one or more compounds selected from the above. The ratio of the peak intensity of the light emitted from the other surface of the light wavelength conversion sheet, which is the surface opposite to the one surface, without being wavelength-converted by the quantum dots to the peak intensity of light is 10% or more. An optical wavelength conversion sheet is provided.

In the light wavelength conversion sheet, before and after the light resistance test in which the light wavelength conversion sheet is irradiated with light for 200 hours in an environment of 42 ° C. and a relative humidity of 50%, each surface of the light wavelength conversion sheet is subjected to. When the brightness of the light emitted from the other surface of the light wavelength conversion sheet is measured by irradiating a predetermined amount of light whose wavelength can be converted by the quantum dots, the light resistance with respect to the brightness before the light resistance test. The maintenance rate of the brightness after the sex test may be 80% or more.

The light wavelength conversion sheet may further include an optical member arranged on at least one surface side of the light wavelength conversion layer and integrated with the light wavelength conversion layer.

In the optical wavelength conversion sheet, 40 ° C. in the light wavelength conversion sheet, the water vapor transmission rate of 90% relative humidity may be 0.1g ^/ (m 2 · 24h) or more.

In the optical wavelength conversion sheet, 23 ° C. in the light wavelength conversion sheet, the oxygen permeability at a relative humidity of 90% may be ^{0.1cm 3 / (m 2 · 24h} · atm) or more.

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

According to another aspect of the present invention, there is provided an image display device including the above-mentioned backlight device and a display panel arranged on the light emitting side of the backlight device.

According to another aspect of the present invention, a light wavelength conversion composition comprising quantum dots and one or more compounds selected from the group consisting of phenolic compounds and amine compounds. Things are provided.

In the light wavelength conversion composition, the content of the compound in the light wavelength conversion composition may be 0.1% by mass or more and 10% by mass or less.

The light wavelength conversion composition may further contain a polymerizable compound.

In the light wavelength conversion composition, the quantum dots form a core made of a first semiconductor compound, a shell made of a second semiconductor compound covering the core and different from the first semiconductor compound, and the shell. It may contain a ligand bound to the surface.

The light wavelength conversion composition may further contain light scattering particles.

According to another aspect of the present invention, there is provided a light wavelength conversion member made of a cured product of the light wavelength conversion composition.

According to the light wavelength conversion sheet of one aspect of the present invention, the light wavelength conversion layer contains one or more compounds selected from the group consisting of phenolic compounds and amine compounds, and thus has excellent heat resistance. It is possible to provide an optical wavelength conversion sheet which has moisture and heat resistance and light resistance, can omit a barrier member, or can suppress punctate brightness defects even when a barrier member is used. Further, according to the light wavelength conversion sheet according to one aspect of the present invention, the light is incident on one surface of the light wavelength conversion sheet when one surface of the light wavelength conversion sheet is irradiated with light capable of wavelength conversion by the quantum dots. Since the ratio of the peak intensity of the light emitted from the other surface of the optical wavelength conversion sheet without being wavelength-converted by the quantum dots to the peak intensity of the light is 10% or more, the emission efficiency is lowered. Excellent heat resistance, moisture heat resistance and light resistance can be obtained while suppressing the heat resistance. Further, according to another aspect of the present invention, it is possible to provide a backlight device and an image display device including such a light wavelength conversion sheet. Furthermore, according to the light wavelength conversion composition of another aspect of the present invention and the light wavelength conversion member of another aspect, one or more compounds selected from the group consisting of phenol-based compounds and amine-based compounds are contained. Therefore, it is possible to provide a light wavelength conversion composition and a light wavelength conversion member having excellent heat resistance, moisture heat resistance and light resistance.

It is a schematic block diagram of the light wavelength conversion sheet which concerns on embodiment. It is a figure which shows the operation of the light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. FIG. 5 is a cross-sectional view taken along the line I-I of the optical wavelength conversion sheet of FIG. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a figure which shows typically the manufacturing process of the light wavelength conversion sheet which concerns on embodiment. It is a figure which shows typically the manufacturing process of the light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the image display device including the backlight device which concerns on embodiment. It is a perspective view of the lens sheet shown in FIG. FIG. 2 is a cross-sectional view taken along the line II-II of the lens sheet of FIG. It is a schematic block diagram of another backlight apparatus which concerns on embodiment. It is a schematic block diagram of another backlight apparatus which concerns on embodiment. It is a schematic block diagram of the light source shown in FIG. It is a schematic block diagram of another backlight apparatus which concerns on embodiment. It is an enlarged view near the light entry surface of the optical plate shown in FIG.

Hereinafter, the light wavelength conversion composition, the light wavelength conversion member, the light wavelength conversion sheet, the backlight device, and the image display device according to the embodiment of the present invention will be described with reference to the drawings. In the present specification, terms such as "sheet" and "film" are not distinguished from each other based only on the difference in designation. Therefore, for example, "sheet" is used to include a member that can also be called a film, and "film" is used to include a member that can also be called a sheet. FIG. 1 is a schematic configuration diagram of an optical wavelength conversion sheet according to the present embodiment, FIG. 2 is a diagram showing the operation of the optical wavelength conversion sheet according to the present embodiment, and FIGS. 3 to 5, 7, and 8 show the operation of the optical wavelength conversion sheet. Is a schematic configuration diagram of another light wavelength conversion sheet according to the present embodiment, FIG. 6 is a cross-sectional view of the light wavelength conversion sheet of FIG. 5 along the line I-I, and FIGS. 9 and 10 show the present embodiment. It is a figure which shows typically the manufacturing process of the light wavelength conversion sheet which concerns on a form.

<<< Light wavelength conversion composition >>>
The optical wavelength conversion composition is a composition for converting the wavelength of a part of the incident light into another wavelength and emitting the other part of the incident light and the wavelength-converted light. The optical wavelength conversion composition comprises quantum dots and one or more compounds selected from the group consisting of phenolic compounds and amine compounds (hereinafter, this compound may be referred to as a "specific compound"). Including. The light wavelength conversion composition may be used in the state of the composition, or may be used in the state of the light wavelength conversion member which is a cured product by curing the light wavelength conversion composition. In the present specification, the "light wavelength conversion member" is a member substantially made of a cured product of the light wavelength conversion composition, and is a concept including a light wavelength conversion layer. Here, the shape of the light wavelength conversion member is not limited and does not have to be layered. Further, the above-mentioned "substantially" means that the light wavelength conversion member may contain a little other substance or the like in addition to the cured product of the light wavelength conversion composition. The light wavelength conversion member may be a member consisting only of a cured product of the light wavelength conversion composition. When forming the light wavelength conversion member, the light wavelength conversion composition further contains a polymerizable compound, and may further contain a polymerization initiator in addition to the polymerizable compound. The light wavelength conversion composition preferably further contains light-scattering particles, and may also contain additives and solvents.

The viscosity of the optical wavelength conversion composition is preferably 10 mPa · s or more and 10000 mPa · s or less. If the viscosity of the light wavelength conversion composition is less than 10 mPa · s, it may be difficult to form a sufficient film thickness, and if it exceeds 10000 mPa · s, when the light wavelength conversion composition is applied, it may be difficult to form a sufficient film thickness. It becomes difficult to apply and the leveling property may deteriorate. The lower limit of the viscosity of the light wavelength conversion composition is preferably 10 mPa · s or more, and the upper limit of the viscosity of the light wavelength conversion composition is preferably 10000 mPa · s or less.

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

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

As the quantum dots, one type of quantum dots may be used, but it is also possible to use two or more types of quantum dots, each of which has an emission band in a single wavelength range, depending on the particle size or material. .. Specifically, the optical wavelength conversion composition may include a first quantum dot and a second quantum dot having an emission band in a wavelength range different from that of the first quantum dot.

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

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

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

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

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

The ligand is for stabilizing unstable quantum dots. Examples of the ligand include sulfur compounds such as thiol, phosphorus compounds such as phosphine compounds or phosphine oxides, nitrogen compounds such as amines, and carboxylic acids.

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

Information such as the particle size, average particle size, shape, and dispersion state of the quantum dots can be obtained by a transmission electron microscope or a scanning transmission electron microscope. The average particle size of the quantum dots can be obtained as the average value of the diameters of the 20 quantum dots measured by observation with a transmission electron microscope or a scanning transmission electron microscope. Further, since the emission color of the quantum dot changes depending on the particle size, it is possible to obtain the particle size of the quantum dot by confirming the emission color of the quantum dot. Further, the crystal structure and crystallite size of the quantum dots can be known by X-ray crystal diffraction (XRD). Furthermore, information on the particle size of quantum dots and the like can be obtained from the ultraviolet-visible (UV-Vis) absorption spectrum.

The content of the quantum dots with respect to the total solid content mass of the optical wavelength conversion composition is preferably 0.01% by mass or more and 2% by mass or less, and more preferably 0.03% by mass or more and 1% by mass or less. .. If the quantum dot content is less than 0.01% by mass, sufficient emission intensity may not be obtained, and if the quantum dot content exceeds 2% by mass, sufficient excitation light is transmitted. There is a risk that strength will not be obtained.

<< Specific compound >>
The specific compound used in the present invention is one or more compounds selected from the group consisting of phenolic compounds and amine compounds. In the present specification, the "phenolic compound" means a compound having a phenolic hydroxyl group in the molecule, and the "amine compound" means a compound having an amino group in the molecule.

The specific compound may contain a polymerizable functional group. When the specific compound contains a polymerizable functional group, it can be polymerized with the polymerizable compound and the specific compound can be immobilized in the binder resin. Examples of the polymerizable functional group include ethylenically unsaturated groups such as a (meth) acryloyl group, a vinyl group, and an allyl group. When the specific compound contains a polymerizable functional group, the specific compound may contain one or more polymerizable functional groups, but may contain two or more.

The specific compound preferably does not have a maximum absorption wavelength in the visible light region having a wavelength of 380 nm or more and 780 nm or less. Since the specific compound does not have a maximum absorption wavelength in the visible light region, a decrease in luminous efficiency can be suppressed. The "maximum absorption wavelength" in the visible light region means the wavelength at which the absorbance is maximized in the visible light absorption spectrum. Further, the specific compound preferably has an absorbance of 0.05 or less in the visible light absorption spectrum from the viewpoint of suppressing a decrease in wavelength conversion efficiency. The maximum absorption wavelength and the absorbance can be obtained by taking out the specific compound from the light wavelength conversion composition and measuring the visible light absorption spectrum of the specific compound. When the specific compound can be specified by the method described later, the maximum absorption wavelength and the absorbance may be obtained from the known visible light absorption spectrum of the specified specific compound.

The specific compound preferably does not have a maximum absorption wavelength in the ultraviolet light region having a wavelength of 230 nm or more and less than 380 nm. Since the specific compound does not have a maximum absorption wavelength in this region, it is possible to suppress curing defects when the light wavelength conversion composition is cured by ultraviolet rays. The "maximum absorption wavelength" in the ultraviolet light region means the wavelength at which the absorbance is maximized in the ultraviolet light absorption spectrum. Further, from the viewpoint of suppressing curing failure, the specific compound preferably has an absorbance of 1 or less in a region having a wavelength of 230 nm or more and less than 380 nm in the ultraviolet light absorption spectrum. The maximum absorption wavelength and the absorbance can be obtained by taking out the specific compound from the light wavelength conversion composition and measuring the ultraviolet light absorption spectrum of the specific compound. When the specific compound can be specified by the method described later, the maximum absorption wavelength and the absorbance may be obtained from the known ultraviolet light absorption spectrum of the specified specific compound.

Whether or not the above-mentioned specific compound is contained in the light wavelength conversion composition is determined by (1) infrared spectroscopic analysis (IR), (2) gas chromatography analysis (GCMS), and (3) gel permeation chromatography analysis. It can be confirmed by using (GPC) and nuclear magnetic resonance spectroscopy (NMR spectroscopy) in combination. Specifically, in the infrared spectroscopic analysis, the compound contained in the light wavelength conversion composition can be roughly specified, and in the gas chromatography analysis, the molecular weight of the compound contained in the light wavelength conversion composition can be specified, and the gel can be specified. In the permeation chromatography analysis, the compounds contained in the light wavelength conversion composition can be separated, and in the nuclear magnetic resonance spectroscopic analysis, the structural formulas of the compounds contained in the light wavelength conversion composition can be specified. By using it, it can be confirmed whether or not the above-mentioned specific compound is contained in the light wavelength conversion composition.

The content of the specific compound in the light wavelength conversion composition is preferably 0.1% by mass or more and 10% by mass or less. If the content of the specific compound is less than 0.1% by mass, deterioration of the quantum dots may not be suppressed during the heat resistance test, the moist heat resistance test, and the light resistance test, and if it exceeds 10% by mass. , There is a risk of causing a decrease in light extraction efficiency due to poor curing or increased absorption in the visible light region. The content of the specific compound can be confirmed by the same method as the method for confirming whether or not the specific compound is present in the light wavelength conversion composition. Specifically, for example, a specific compound contained in the optical wavelength conversion composition is identified (identified) by nuclear magnetic resonance spectroscopy, and then gas chromatography analysis or gel permeation chromatography corresponding to the specific compound is performed. From the peak area ratio obtained by the analysis, the content of the specific compound in the optical wavelength conversion composition can be determined. When a plurality of types of the specific compound are used, the content means the total content of the plurality of types of the specific compound. The lower limit of the content of the specific compound in the light wavelength conversion composition is more preferably 0.5% by mass or more, and the upper limit of the content of the specific compound is preferably 8% by mass or less. ..

<Phenolic compounds>
The phenolic compound is not particularly limited, but a hindered phenolic compound is preferable from the viewpoint of obtaining an excellent antioxidant function. The "hindered phenolic compound" means that the hydrogen atom on the carbon at the ortho position with respect to the phenolic hydroxyl group of the aromatic ring constituting the phenolic compound is substituted with a substituent (preferably a substituted or unsubstituted alkyl group). Means a compound.

Examples of the phenolic compound include 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-4-ethylphenol, and 2,6-dicyclohexyl-4-methylphenol, 2. , 6-Diisopropyl-4-ethylphenol, 2,6-di-t-amyl-4-methylphenol, 2,6-di-t-octyl-4-n-propylphenol, 2,6-dicyclohexyl-4- n-octylphenol, 2-isopropyl-4-methyl-6-t-butylphenol, 2-t-butyl-4-ethyl-6-t-octylphenol, 2-isobutyl-4-ethyl-6-t-hexylphenol, 2 Monocyclic phenols such as −cyclohexyl-4-n-butyl-6-isopropylphenol, styrene mixed cresol, DL-α-tocopherol, stearyl β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate System compounds; 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 4,4'-thiobis (3-methyl- 6-t-butylphenol), 2,2'-thiobis (4-methyl-6-t-butylphenol), 4,4'-methylenebis (2,6-di-t-butylphenol), 2,2'-methylenebis [ 6- (1-methylcyclohexyl) -p-cresol], 2,2'-ethylidenebis (4,6-di-t-butylphenol), 2,2'-butylidenebis (2-t-butyl-4-methylphenol) ), 3,6-Dioxaoctamethylenebis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate], triethylene glycolbis [3- (3-t-butyl-5-methyl) -4-Hydroxyphenyl) propionate], 1,6-hexanediol bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2'-thiodiethylenebis [3-(3) Bicyclic phenolic compounds such as 3,5-di-t-butyl-4-hydroxyphenyl) propionate; 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-Tris (2,6-dimethyl-3-hydroxy-4-t-butylbenzyl) isocyanurate, 1,3,5-tris [(3,5-di-t-butyl-4-hydroxy) Phenyl) propionyloxyethyl] Isocyanurate, 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, tris (4-t-butyl-2,6-dimethyl-3-hydroxybenzyl) isocyanurate , 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene and other tricyclic phenolic compounds; tetrakis [methylene-3- (3,3) 5-Di-t-Butyl-4-hydroxyphenyl) propionate] A tetracyclic phenolic compound such as methane; bis (3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl) calcium, bis (3, Examples thereof include phosphorus-containing phenolic compounds such as 5-di-t-butyl-4-hydroxybenzylphosphonate ethyl) nickel. Among these, phenolic compounds include stearyl β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and 1,3,5-tris (3,5-di-t-butyl-4). -Hydroxybenzyl) isocyanurate, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane and the like are preferable. Two or more kinds of phenolic compounds may be used.

The weight average molecular weight of the phenolic compound is preferably 200 or more and 2000 or less from the viewpoint of volatility and compatibility. In the present specification, the "weight average molecular weight" is a value obtained by dissolving in a solvent such as tetrahydrofuran (THF) and converting into polystyrene by a conventionally known gel permeation chromatography (GPC) method. The lower limit of the weight average molecular weight of the phenolic compound is more preferably 400 or more, and the upper limit is more preferably 1200 or less.

Examples of commercially available products of the phenolic compounds include IRGANOX1076, IRGANOX3114, and IRGANOX1010 (all manufactured by BASF).

<Amine compounds>
The amine compound is not particularly limited, but a hindered amine compound is preferable from the viewpoint of obtaining an excellent antioxidant function. The "hindered amine compound" includes a piperidine ring in the molecule, and all hydrogen atoms on the carbon at the 2- and 6-positions of the piperidine ring are substituted with a substituent (preferably an alkyl group which may be substituted). Means the compound.

Examples of amine compounds include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, dimethyl succinate and 1- (2-hydroxyethyl) -4-hydroxy-2,2,6. Polycondensate of 6-tetramethylpiperidineethanol, N, N', N'', N'''-tetrakis- (4,6-bis- (butyl- (N-methyl-2,2,6,6-) Tetramethylpiperidin-4-yl) amino) -triazine-2-yl) -4,7-diazadecan-1,10-diamine, dibutylamine 1,3,5-triazine N, N'-bis (2, Polycondensate of 2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxy Rate, 2,2,6,6-tetramethyl-4-piperidylbenzoate, bis- (1,2,6,6-pentamethyl-4-piperidyl) -2- (3,5-di-t-butyl) -4-Hydroxybenzyl) -2-n-butylmalonate, bis- (N-methyl-2,2,6,6-tetramethyl-4-piperidyl) sebacate, 1,1'-(1,2-ethanediyl) ) Bis (3,3,5,5-tetramethylpiperazinone), (mixed 2,2,6,6-tetramethyl-4-piperidyl / tridecyl) -1,2,3,4-butanetetracarboxy Rate, (mixed 1,2,2,6,6-pentamethyl-4-piperidyl / tridecyl) -1,2,3,4-butanetetracarboxylate, mixed [2,2,6,6-tetramethyl] -4-Piperidyl / β, β, β', β'-Tetramethyl-3,9- [2,4,8,10-tetraoxaspiro (5,5) undecane] diethyl] -1,2,3 4-butanetetracarboxylate, mixed [1,2,2,6,6-pentamethyl-4-piperidyl / β, β, β', β'-tetramethyl-3,9- [2,4,8, 10-Tetraoxaspiro (5,5) undecane] diethyl] -1,2,3,4-butanetetracarbo Xylate, N, N'-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6- Chloro-1,3,5-triazine condensate, poly [6-N-morpholyl-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) ) Imino] Hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imide], N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) Hexamethylenediamine Condensation of 1,2-dibromoethane, [N- (2,2,6,6-tetramethyl-4-piperidyl) -2-methyl, 1,2,2,6,6-pentamethyl methacrylate- 4-Piperidil and the like can be mentioned. Among these, amine compounds include (mixed 1,2,2,6,6-pentamethyl-4-piperidyl / tridecylic) -1,2,3,4-butanetetracarboxylate and bis (2,2). , 6,6-tetramethyl-4-piperidyl) sebacate, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate and the like are preferable. Two or more kinds of amine compounds may be used.

The weight average molecular weight of the amine compound is preferably 150 or more and 2000 or less from the viewpoint of volatileness and compatibility. The lower limit of the weight average molecular weight of the amine compound is more preferably 200 or more, and the upper limit is more preferably 1000 or less.

Examples of commercially available products of the amine compounds include LA-52, LA-72, and LA-82 (all manufactured by ADEKA Corporation).

<< Polymerizable compound >>
The polymerizable compound (curable compound) is a polymerizable compound, and examples thereof include an ionizing radiation polymerizable compound (ionizing radiation curable compound) and a thermosetting compound (thermosetting compound). Examples of ionizing radiation in the present specification include visible light and ultraviolet rays, X-rays, electron beams, α-rays, β-rays, and γ-rays.

The content of the polymerizable compound with respect to the total solid content mass of the light wavelength conversion composition is preferably 30% by mass or more and 95% by mass or less, and preferably 50% by mass or more and 90% by mass or less. If the content of the polymerizable compound is less than 30% by mass, sufficient curability may not be obtained when forming the light wavelength conversion member, and the content of the polymerizable compound exceeds 95% by mass. In addition, the effects of improving heat resistance, moisture heat resistance, and light resistance of the specific compound may not be sufficiently obtained. When the light wavelength conversion composition contains both an ionizing radiation polymerizable compound and a thermopolymerizable compound described later, the above content means the total content of the ionizing radiopolymerizable compound and the thermopolymerizable compound. It shall be.

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

Examples of the ionizing radiation-polymerizable compound include an ionizing radiation-polymerizable monomer, an ionizing radiation-polymerizable oligomer, and an ionizing radiation-polymerizable prepolymer, which can be appropriately adjusted and used. As the ionizing radiation-polymerizable compound, a combination of an ionizing radiation-polymerizable monomer and an ionizing radiation-polymerizable oligomer or an ionizing radiation-polymerizable prepolymer is preferable.

Examples of the ionizing radiation polymerizable monomer include a monomer containing a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate, and 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, trimethyl propantri (meth) acrylate, trimethylol ethanetri (meth) ) Acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, glycerol (meth) acrylate (Meta) acrylic acid esters such as, etc. can be mentioned.

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

The ionizing radiation polymerizable prepolymer has a weight average molecular weight of more than 10,000, and the weight average molecular weight is preferably 10,000 or more and 80,000 or less, and more preferably 10,000 or more and 40,000 or less. When the weight average molecular weight exceeds 80,000, the viscosity is high, so that the coating suitability is lowered, and the appearance of the obtained light wavelength conversion member may be deteriorated. Therefore, when an ionizing radiation-polymerizable prepolymer having a weight average molecular weight of more than 80,000 is used, it is preferable to mix and use the above-mentioned polymerizable monomer and the above-mentioned polymerizable oligomer. Examples of the polyfunctional polymerizable prepolymer include urethane (meth) acrylate, isocyanurate (meth) acrylate, polyester-urethane (meth) acrylate, and epoxy (meth) acrylate.

<Thermopolymerizable compound>
The thermopolymerizable compound has at least one thermopolymerizable functional group in the molecule. Examples of the thermopolymerizable functional group include a cyclic ether group such as an epoxy group and an oxetanyl group, a vinyl ether group and the like.

Examples of the thermopolymerizable compound include a cyclic ether compound having one or more cyclic ether groups in the molecule, such as an epoxy compound and an oxetane compound, and a vinyl ether compound. As the cationically polymerizable compound, a cyclic ether compound is preferable from the viewpoint of further suppressing the occurrence of tunneling, and an epoxy compound is preferable among the cyclic ether compounds.

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

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

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

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

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

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

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

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

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

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

The content of the polymerization initiator in the light wavelength conversion composition is preferably 0.3 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the polymerizable compound. If the content of the polymerization initiator is less than 0.3 parts by mass, the polymerizable compound is difficult to cure, and if it exceeds 5.0 parts by mass, the optical wavelength conversion sheet may turn yellow. ..

<< Light-scattering particles >>
The light scattering particles are particles having an action of changing the traveling direction of light by scattering the light that has entered the light wavelength conversion member.

The average particle size of the light-scattering particles is preferably 20 times or more and 2000 times or less, and more preferably 50 times or more and 1000 times or less of the average particle size of the quantum dots. If the average particle size of the light-scattering particles is less than 20 times the average particle size of the quantum dots, sufficient light-scattering performance may not be obtained in the light wavelength conversion member, and the average particle size of the light-scattering particles becomes If it exceeds 2000 times the average particle size of the quantum dots, the number of light-scattering particles will decrease even if the amount added is the same, so the number of scattering points may decrease and a sufficient light-scattering effect may not be obtained. .. The average particle size of the light-scattering particles can be measured by the same method as the average particle size of the quantum dots described above.

Further, the average particle size of the light scattering particles is preferably 1/300 or more and 1/20 or less, and more preferably 1/200 or more and 1/30 or less of the average film thickness of the light wavelength conversion member described later. preferable. If the average particle size of the light-scattering particles is less than 1/300 of the average film thickness of the light-scattering member, sufficient light-scattering performance may not be obtained in the light-scattering member, and the average of the light-scattering particles. If the particle size exceeds 1/20 of the average film thickness of the light wavelength conversion member, the ratio of light scattering particles to the light wavelength conversion member decreases even if the amount added is the same, so that the number of scattering points is sufficiently reduced. No light scattering effect can be obtained.

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

The shape of the light-scattering particles is not particularly limited, and for example, spherical (true spherical, substantially true spherical, elliptical spherical, etc.), polyhedral, rod-shaped (cylindrical, prismatic, etc.), flat plate, flaky, and indefinite shape. And so on. When the shape of the light-scattering particles is not spherical, the particle size of the light-scattering particles can be a true spherical value having the same volume.

The light-scattering particles are preferably surface-treated with a silane coupling agent from the viewpoint of firmly fixing the light-scattering particles in the binder resin. By surface-treating with a silane coupling agent, it can be chemically bonded to a binder resin described later.

The silane coupling agent is a group consisting of a vinyl group, an epoxy group, a styryl group, a methacryl group, an acrylic group, an amino group, a ureido group, a thiol group, a sulfide group and an isocyanate group, although it depends on the type of the polymerizable compound used. It is possible to use one having one or more reactive functional groups selected from. When a compound having a (meth) acryloyl group is used as the polymerizable compound, the coupling agent is at least one reactive material selected from the group consisting of a thiol group, a (meth) acryloyl group, a vinyl group and a styryl group. It preferably has a functional group. When a compound having at least one group selected from the group consisting of an epoxy group, an isocyanate group and a hydroxyl group is used as the polymerizable compound, the silane coupling agent is an epoxy group, an isocyanate group, a thiol group and an amino. It preferably has at least one reactive functional group selected from the group consisting of groups.

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

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

The content of the light scattering particles with respect to the total solid content mass of the light wavelength conversion 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. If the content of the light scattering particles is less than 1% by mass, the light scattering effect may not be sufficiently obtained, and if the content of the light scattering particles exceeds 50% by mass, Mie scattering occurs. Since it becomes difficult, there is a possibility that the light scattering effect cannot be sufficiently obtained, and further, there is a possibility that the processability is lowered because there are too many light scattering particles.

<< Additives >>
The additive is not particularly limited, but a compound that suppresses oxidation and deterioration of quantum dots is preferable. Examples of the compound that suppresses oxidation and deterioration of quantum dots include sulfur-based compounds, phosphorus-based compounds, hydrazine-based compounds, and amide-based compounds. The additive may have a polymerizable functional group such as an ionizing radiation polymerizable functional group or a thermally polymerizable functional group.

<< Solvent >>
The solvent is not particularly limited, and examples thereof include alcohols such as methanol, ethanol, propanol and isopropyl alcohol; ketones such as methyl ethyl ketone and methyl isobutyl ketone, toluene and cyclohexane.

<<< Light wavelength conversion sheet >>>
The light wavelength conversion sheet 10 shown in FIG. 1 is a sheet that converts the wavelength of a part of the incident light into another wavelength and emits the other part of the incident light and the wavelength-converted light. is there. The light wavelength conversion sheet 10 shown in FIG. 1 includes a light wavelength conversion layer 11, light transmitting base materials 12 and 13 provided on both sides of the light wavelength conversion layer 11, and light in the light transmitting base materials 12 and 13. It includes light diffusion layers 14 and 15 provided on the side opposite to the surface on the wavelength conversion layer 11 side. In the light wavelength conversion sheet 10, the surfaces of the light diffusion layers 14 and 15 constitute the surfaces 10A and 10B of the light wavelength conversion sheet 10. The light wavelength conversion sheet 10 includes the light-transmitting base materials 12 and 13, but does not have a barrier layer, so that it does not have a barrier member composed of the light-transmitting base material and the barrier layer. The light wavelength conversion sheet 10 has a structure of a light diffusion layer 14 / a light transmission base material 12 / a light wavelength conversion layer 11 / a light transmission base material 13 / a light diffusion layer 15, but is a light wavelength conversion layer. The structure of the optical wavelength conversion sheet is not particularly limited as long as it has.

In the optical wavelength conversion sheet 10, as shown in FIG. 2, when light is incident from the surface 10A of the optical wavelength conversion sheet 10, the light L1 incident on the quantum dots 17 in the optical wavelength conversion layer 11 is generated. It is converted into light L2 having a wavelength different from that of light L1 and emitted from the surface 10B opposite to the surface 10A. On the other hand, even when light is incident from the surface 10A, the light L1 passing between the quantum dots 17 in the optical wavelength conversion layer 11 is emitted from the surface 10B without being wavelength-converted.

In the optical wavelength conversion sheet 10, when one surface 10A of the optical wavelength conversion sheet 10 is irradiated with light whose wavelength can be converted by the quantum dots 17, the peak intensity of the light incident on the surface 10A of the optical wavelength conversion sheet 10 is relative to the peak intensity of the light. The ratio of the peak intensity of the light emitted from the other surface 10B of the light wavelength conversion sheet 10 without being wavelength-converted by the quantum dots 17 (hereinafter, this ratio may be referred to as "light emission ratio of incident light"). It is 10% or more. When the light wavelength conversion layer includes, for example, both quantum dots that convert blue light into green light and quantum dots that convert blue light into red light, the light that can be wavelength-converted by the quantum dots is blue light. Can be used. When the light incident on the optical wavelength conversion sheet is, for example, blue light, the emission ratio of the incident light is not wavelength-converted by the quantum dots with respect to the peak intensity of the blue light incident on one surface of the optical wavelength conversion sheet. It means the ratio of the peak intensity of the blue light emitted from the other surface of the light wavelength conversion sheet. That is, since a part of the blue light incident on one surface of the light wavelength conversion sheet is converted into green light or red light by the quantum dots, only the blue light that has not been wavelength-converted from the other surface of the light wavelength conversion sheet. Instead, wavelength-converted green light or red light is emitted, but when determining the emission ratio of the incident light, only the blue light emitted from the other surface of the light length conversion sheet is considered, and other than blue light. Green light and red light of are not considered. The light emission ratio of the incident light may be 20% or more.

Regarding the light emission ratio of the incident light, the light emission ratio of the incident light is A, the peak intensity of the light incident on the surface 10A of the light wavelength conversion sheet 10 is B, and the wavelength of the light wavelength conversion sheet 10 is not converted by the quantum dots 17. When the peak intensity of the light emitted from the surface 10B is C, it can be obtained by the following formula (1). The light emission ratio of the incident light shall be the average value of the values obtained by measuring three times.
A = C / B × 100 ... (1)

The peak intensity of the light incident on the surface 10A of the light wavelength conversion sheet 10 is the brightness of the light emitted from the backlight device using a backlight device in which the light wavelength conversion sheet 10 is not incorporated, and the thickness of the backlight device. Measured and measured at a position 400 mm away from the light emitting surface (surface) of the backlight device in the direction, using a spectral radiance meter (product name "CS2000", manufactured by Konica Minolta) under the condition of a measurement angle of 1 °. It shall be obtained from the brightness distribution. Further, the peak intensity of the light emitted from the surface 10B of the light wavelength conversion sheet 10 is the brightness of the light emitted from the backlight device in the state where the light wavelength conversion sheet 10 is incorporated in the backlight device. Measured at a position 400 mm away from the light emitting surface (surface) of the backlight device in the thickness direction of the above, using a spectral radiance meter (product name "CS2000", manufactured by Konica Minolta) under the condition of a measuring angle of 1 °. It shall be obtained from the measured brightness distribution.

In the light wavelength conversion sheet 10, before and after the heat resistance test in which the light wavelength conversion sheet 10 is left in an environment of 80 ° C. for 500 hours, the wavelength can be converted to the surface 10A of one surface of the light wavelength conversion sheet by the quantum dots 17. When the brightness of the light emitted from the other surface 10B, which is the surface opposite to the surface 10A of the light wavelength conversion sheet 10, is measured by irradiating the light of the above amount of light, the light wavelength conversion sheet 10 before the heat resistance test is measured. It is preferable that the maintenance rate of the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 after the heat resistance test with respect to the brightness of the light emitted from the surface 10B is 80% or more. The maintenance rate of the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 after the heat resistance test is 90% or more with respect to the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 before the heat resistance test. More preferred.

The brightness retention rate before and after the heat resistance test is such that the brightness maintenance rate is E, the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 before the heat resistance test is F, and the light wavelength conversion sheet after the heat resistance test. When the brightness of the light emitted from the surface 10B of 10 is G, it can be obtained by the following equation (2). The brightness maintenance rate before and after the heat resistance test is the average value of the values obtained by measuring three times.
E = G / F × 100… (2)

For the brightness before and after the heat resistance test, the light emitted from the other surface of the light wavelength conversion 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 is performed under the condition of a measurement angle of 1 °.

In the light wavelength conversion sheet 10, before and after the moist heat resistance test in which the light wavelength conversion sheet 10 is left in an environment of 60 ° C. and a relative humidity of 90% for 500 hours, the quantum dots 17 are applied to one surface 10A of the light wavelength conversion sheet. When the brightness of the light emitted from the other surface 10B, which is the surface opposite to the surface 10A of the light wavelength conversion sheet 10, is measured by irradiating a predetermined amount of light to be wavelength-converted, before the moist heat resistance test. It is preferable that the maintenance rate of the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 after the moist heat resistance test with respect to the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 is 80% or more. The maintenance rate of the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 after the moisture resistance test is 90% or more with respect to the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 before the moisture resistance test. More preferred.

For the brightness retention rate before and after the moisture resistance test, the brightness retention rate is H, the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 before the moisture resistance test is I, and the light wavelength conversion sheet after the moisture resistance test. When the brightness of the light emitted from the surface 10B of 10 is J, it can be obtained by the following equation (3). The brightness maintenance rate before and after the moisture resistance test is the average value of the values obtained by measuring three times.
H = J / I × 100… (3)

For the brightness before and after the moisture resistance test, the light emitted from the other surface of the light wavelength conversion 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 is performed under the condition of a measurement angle of 1 °.

In the light wavelength conversion sheet 10, a light resistance test in which the light wavelength conversion sheet 10 is irradiated with light (for example, light from a carbon arc lamp) for 200 hours in an environment of 42 ° C. and a relative humidity of 50%. Before and after, when the surface 10A of the light wavelength conversion sheet 10 is irradiated with a predetermined amount of light and the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 is measured, the light wavelength conversion sheet before the light resistance test is performed. It is preferable that the maintenance rate of the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 after the light resistance test with respect to the brightness of the light emitted from the surface 10B of 10 is 80% or more. The maintenance rate of the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 after the light resistance test is 90% or more with respect to the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 before the light resistance test. More preferred.

The brightness retention rate before and after the light resistance test is such that the brightness maintenance rate is L, the brightness of the light emitted from the surface 10B of the light wavelength conversion sheet 10 before the light resistance test is M, and the light wavelength conversion sheet after the light resistance test. When the brightness of the light emitted from the surface 10B of 10 is N, it can be obtained by the following equation (4). The brightness maintenance rate before and after the light resistance test is the average value of the values obtained by measuring three times.
L = N / M × 100… (4)

The light resistance test can be performed using a light resistance tester (product name "ultraviolet fade meter U48AU", manufactured by Suga Test Instruments Co., Ltd.). The brightness before and after the light resistance test is the spectral radiance meter (product name "CS2000", manufactured by Konica Minolta) that emits light emitted from the other surface of the light wavelength conversion sheet from the thickness direction of the light wavelength conversion sheet. Is measured under the condition of a measurement angle of 1 °.

As the light irradiated on one surface of the optical wavelength conversion sheet in the heat resistance test, the moist heat resistance test, and the light resistance test, if the light that can be wavelength-converted by the quantum dots is included, the light that is not wavelength-converted by the quantum dots is used. It may be included. When the light wavelength conversion layer includes, for example, both quantum dots that convert blue light into green light and quantum dots that convert blue light into red light, the light that can be wavelength-converted by the quantum dots is blue light. Can be used. The reason why the light wavelength conversion sheet is irradiated with a predetermined amount of light before and after the heat resistance test, etc. is that accurate brightness is maintained when the light wavelength conversion sheet is irradiated with light of different light amounts before and after the heat resistance test, etc. Since the rate cannot be measured, it was decided to irradiate the light wavelength conversion sheet with a certain amount of light before and after the heat resistance test or the like in order to measure the accurate brightness maintenance rate.

The brightness of the light emitted from the other surface of the light wavelength conversion sheet in the heat resistance test, the moisture heat resistance test, and the light resistance test directly or indirectly measures the brightness of the light emitted from the other surface of the light wavelength conversion sheet. It can be obtained by doing. That is, it may be obtained by directly measuring the brightness of the light emitted from the other surface of the light wavelength conversion sheet, but the light wavelength conversion sheet is incorporated into a backlight device provided with a light source, a lens sheet, or the like to convert the light wavelength. It may be obtained by measuring the brightness of the light emitted from the light emitting surface of the backlight device through the other surface of the sheet. However, it goes without saying that the measurement of the brightness before the heat resistance test and the like and the measurement of the brightness after the heat resistance test and the like are performed under the same conditions. When the brightness is measured while being incorporated in the backlight device, the brightness is measured at a position 400 mm away from the light emitting surface (surface) of the backlight device in the thickness direction of the backlight device.

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

In the optical wavelength conversion sheet 10, the entire sheet, 23 ° C., the oxygen permeability at a relative humidity of 90% (OTR: Oxygen Transmission Rate ) is not a ^{0.1cm 3 / (m 2 · 24h} · atm) or higher May be good. 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). The oxygen permeability shall be the average value of the values obtained by measuring three times. Since the conventional light wavelength conversion sheet has a barrier member formed therein, 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 has a higher oxygen transmittance. Compared to the conventional light wavelength conversion sheet, not only water but also oxygen is easily transmitted. Similarly to the above, when the light wavelength conversion sheet includes an optical member in addition to the light wavelength conversion layer, the oxygen transmittance is the oxygen transmittance of the entire light wavelength conversion sheet including the optical member.

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

The internal haze value of the optical wavelength conversion sheet 10 is preferably 50% or more. The internal haze is a haze value caused by the inside of the light wavelength conversion sheet, and does not take into account the uneven shape of the surface of the light wavelength conversion sheet. When the internal haze value of the optical wavelength conversion sheet 10 is 50% or more, the light can be sufficiently diffused by the internal haze to excite the quantum dots multiple times, and the external haze value can be made smaller. Can be done. The internal haze value of the optical wavelength conversion sheet 10 is preferably 60% or more, and more preferably 80% or more.

The external haze value in the optical wavelength conversion sheet 10 is preferably 10% or less (including 0%), and more preferably 5% or less. The external haze value is caused only by the uneven shape of the surface of the optical wavelength conversion sheet. When the external haze value of the light wavelength conversion sheet 10 is 10% or less, retroreflection is likely to occur in a retroreflective sheet such as a lens sheet.

In the light wavelength conversion sheet 10, it is preferable that the external haze value of the light wavelength conversion sheet 10 is smaller than the internal haze value of the light wavelength conversion sheet 10. That is, it is preferable that the light wavelength conversion sheet 10 satisfies the relationship of the following formula.
Internal haze value> External haze value

The internal haze value and the external haze value can be obtained using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Laboratory). Specifically, first, using a haze meter, the total haze value of the optical wavelength conversion sheet is measured according to JIS K7136: 2000. After that, a triacetyl cellulose base material having a thickness of 60 μm (product name “Panaclean PD-S1”, manufactured by Panac Co., Ltd.) is interposed on both sides of the optical wavelength conversion sheet via a transparent optical adhesive layer (product name “Panaclean PD-S1”, manufactured by Panac Co., Ltd.) having a thickness of 25 μm (product name “Panaclean PD-S1”). TD60UL ", manufactured by Fujifilm Co., Ltd.) is pasted. As a result, the uneven shape of the surface of the light wavelength conversion sheet is crushed, and the surface of the light wavelength conversion sheet is flattened. Then, in this state, the internal haze value is obtained by measuring the haze value according to JIS K7136: 2000 using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Research Institute). The external haze value is obtained by subtracting the internal haze from the total haze. The "external haze value" in the present specification means the external haze value of the entire light wavelength conversion sheet. That is, the external haze value in the present specification means the sum of the external haze value on one surface of the light wavelength conversion sheet and the external haze value on the other surface of the light wavelength conversion sheet. The internal haze value and the external haze value shall be the average value of the values obtained by measuring each of the three times.

The internal haze value and the external haze value are related. Specifically, as the internal haze value increases, the external haze tends to decrease even if the surface has the same surface irregularities. This is considered to be due to the following reasons. JIS K7136: 2000 stipulates that haze is a percentage of transmitted light passing through a test piece that deviates by 0.044 rad (2.5 °) or more from incident light due to forward scattering. There is. That is, in the definition of haze, transmitted light deviated by 2.5 ° or more with respect to incident light is measured as haze, but transmitted light less than 2.5 ° with respect to incident light is not measured as haze. On the other hand, in the light wavelength conversion sheet having a large internal haze, the light is scattered more inside the sheet as compared with the light wavelength conversion sheet having a smaller internal haze. Transmitted light below 2.5 ° is reduced. Therefore, when the optical wavelength conversion sheet having a large internal haze and the optical wavelength conversion sheet having a smaller internal haze have the same surface unevenness, the optical wavelength conversion sheet having a larger internal haze has a larger internal haze than that. Compared to a small light wavelength conversion sheet, the influence of surface irregularities is reduced. Therefore, when considering only the influence of the surface unevenness existing on the sheet surface, even if the light wavelength conversion sheet having a large internal haze and the light wavelength conversion sheet having a smaller internal haze have the same surface unevenness, the inside Compared to the light wavelength conversion sheet with a smaller internal haze, the light wavelength conversion sheet with a large haze has not only transmitted light of less than 2.5 ° with respect to the incident light emitted from the surface unevenness, but also the surface unevenness. The transmitted light that deviates by 2.5 ° or more with respect to the incident light emitted from the light is also reduced. Therefore, it is considered that when the internal haze value becomes large, the external haze becomes small even if the same surface unevenness is provided.

In the light wavelength conversion sheet 10, in order to make the external haze value of the light wavelength conversion sheet 10 smaller than that of the light wavelength conversion sheet 10, for example, adding light scattering particles to the inside of the light wavelength conversion sheet 10 can be mentioned. .. When the light wavelength conversion sheet includes a barrier member and / or a light diffusing layer, the light scattering particles may be added to the barrier member in addition to the light wavelength conversion layer 11, and the light diffusing layer may be added. It may also be added therein. When the layer to which the light scattering particles are added is the outermost layer, it may be accompanied by an outer haze. Therefore, by controlling the surface unevenness of the outermost layer, the above-mentioned relationship between the inner haze and the outer haze is satisfied. Can be done.

The ratio of the external haze value to the internal haze value (external haze value / internal haze value) in the optical wavelength conversion sheet 10 is preferably 0 or more and 0.1 or less, and more preferably 0 or more and 0.05 or less. .. If this ratio is within this range, the internal haze can sufficiently diffuse the light and excite the quantum dots multiple times.

The arithmetic mean roughness (Ra) of the surfaces 10A and 10B of the optical wavelength conversion sheet 10 is preferably 0.1 μm or more, and more preferably 0.5 μm or more, respectively. The Ra of the surfaces 10A and 10B of the optical wavelength conversion sheet 10 is preferably 0.1 μm for the following reasons. The optical wavelength conversion sheet comes into contact with the optical plate or lens sheet described later in the backlight device, but if the optical wavelength conversion sheet and the optical plate or lens sheet stick to each other, the space between the optical wavelength conversion sheet and the optical plate Since there is a risk that a pattern called wetout, which looks like wetting with water, may be formed at the interface between the light wavelength conversion sheet 10 and the optical wavelength conversion sheet and the lens sheet. Ra is more preferably 0.1 μm or more in order to prevent sticking.

The above definition of "Ra" shall be in accordance with JIS B0601: 1994. Ra can be measured using, for example, a surface roughness measuring instrument (product name "SE-3400", manufactured by Kosaka Laboratory Co., Ltd.). Ra is an average value obtained by randomly measuring 15 points on the surfaces 10A and 10B of the light wavelength conversion sheet where there is no visual abnormality (a place where there is no large foreign matter or scratches).

When a light wavelength conversion sheet 10 containing both quantum dots that convert blue light into green light and quantum dots that convert blue light into red light is irradiated with a light source that emits blue light, the transmitted light in the light wavelength conversion sheet. Of these, the ratio of the peak value of green light intensity to the peak value of blue light intensity (peak value of green light intensity / peak value of blue light intensity) is 0.3 or more and 2.0 or less. It is preferably 0.5 or more and 1.5 or less.

Further, the ratio of the peak value of the light intensity of red light to the peak value of the light intensity of blue light (the peak value of the light intensity of red light / the peak value of the light intensity of blue light) in the transmitted light in the light wavelength conversion sheet 10 is , 0.3 or more and 2.0 or less, and more preferably 0.5 or more and 1.5 or less.

In the present specification, "blue light" is light having a wavelength range of 380 nm or more and less than 480 nm, "green light" is light having a wavelength range of 480 nm or more and less than 590 nm, and "red light" is Light having a wavelength range of 590 nm or more and 750 nm or less. Further, the light intensity of each of the above lights can be measured using a spectral radiance meter (for example, product name "CS2000", manufactured by Konica Minolta Co., Ltd.).

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

The thickness of the light wavelength conversion sheet 10 is 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 points and used as the average value of the thicknesses at the 20 points. Among these, considering that the film thickness of the optical wavelength conversion sheet 10 is on the order of μm, it is preferable to use SEM. In the case of SEM, the acceleration voltage is preferably 30 kV and the magnification is preferably 1000 to 7000 times, and in the case of TEM or STEM, the acceleration voltage is preferably 30 kV and the magnification is preferably 50,000 to 300,000 times.

<< Optical wavelength conversion layer >>
The light wavelength conversion layer 11 is a cured product of the light wavelength conversion composition, and is a kind of light wavelength conversion member. The light wavelength conversion composition in this case contains a polymerizable compound in addition to the quantum dots and the above-mentioned specific compound.

Since the light wavelength conversion layer 11 is a cured product of the light wavelength conversion composition, it contains quantum dots 17, the specific compound, and a binder resin 16 which is a cured product of the polymerizable compound. When the specific compound has a polymerizable functional group, the binder resin may be bonded to the specific compound by the polymerizable functional group of the specific compound.

Whether or not the specific compound is present in the light wavelength conversion layer 11 can be confirmed by the same method as the method for confirming whether or not the specific compound is present in the light wavelength conversion composition. .. The quantum dot 17 shown in FIG. 1 includes a first quantum dot 17A and a second quantum dot 17B having an emission band in a wavelength range different from that of the first quantum dot 17A. Further, the light wavelength conversion layer 11 shown in FIG. 1 further contains light scattering particles 18. By including the light scattering particles 18, the light wavelength conversion efficiency and the internal haze can be improved. The quantum dots 17, the specific compound, and the light scattering particles 18 included in the light wavelength conversion layer 11 are the same as the quantum dots, the specific compound, and the light scattering particles described above. The description shall be omitted.

In the light wavelength conversion layer 11, the content of the specific compound in the light wavelength conversion layer 11 is preferably 0.1% by mass or more and 10% by mass or less. If the content of the specific compound is less than 0.1% by mass, deterioration of the quantum dots may not be suppressed during the heat resistance test, the moist heat resistance test, and the light resistance test, and it exceeds 10% by mass. In addition, there is a risk of causing a decrease in light extraction efficiency due to poor curing or increased absorption in the visible light region. The content of the specific compound in the light wavelength conversion layer 11 can be measured by the same method as the method for measuring the content of the specific compound in the light wavelength conversion composition. The lower limit of the content of the specific compound in the light wavelength conversion layer 11 is more preferably 0.5% by mass or more, and the upper limit of the content of the specific compound is more preferably 8% by mass or less. preferable.

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

<Binder resin>
Since the binder resin 16 is a cured product of the above-mentioned polymerizable compound, it is omitted here.

The absolute value of the difference in refractive index between the light-scattering particles 18 and the binder resin 16 is preferably 0.05 or more, and more preferably 0.10 or more, from the viewpoint of obtaining sufficient light scattering. The refractive index of the light-scattering particles 18 and the refractive index of the binder resin 16 may be larger. Here, as a method for measuring the refractive index of the light scattering particles before being contained in the light wavelength conversion layer, for example, the Becke method, the minimum deviation method, the deviation analysis, the mode line method, the ellipsometry method and the like are used. can do. Regarding the refractive index of the binder resin 16 in the optical wavelength conversion layer 11, for example, 10 pieces of the binder resin 16 are taken out from the light wavelength conversion layer 11 by cutting out or the like, and the 10 pieces taken out are taken out by the Becke method to obtain the binder resin. The refractive index of each of the 16 is measured, and it can be obtained as an average value of 10 refractive indexes of the measured binder resin 16. Further, the refractive index of the light scattering particles 18 in the light wavelength conversion layer 11 is determined by, for example, cutting out a fragment obtained by exposing a part of the surface of the light scattering particles 18 from the binder resin 16 from the light wavelength conversion layer 11. The refractive indexes of the 10 light-scattering particles 18 whose surfaces are exposed by the Becke method are measured in each of the taken-out pieces and obtained as the average value of 10 of the measured refractive indexes of the light-scattering particles 18. it can. In the Becke method, a refractive index standard solution having a known refractive index is used, the fragment is placed on a slide glass or the like, the refractive index standard solution is dropped onto the sample, and the fragment is immersed in the refractive index standard solution. Observing the situation with a microscope, the refractive index of the binder resin or light-scattering particles differs from that of the refractive index standard solution, so that the bright lines (Becke lines) generated on the surface of the binder resin or light-scattering particles cannot be visually observed. This is a method in which the refractive index of the standard liquid is used as the refractive index of the surface of the binder resin or light-scattering particles. When the light-scattering particles are not exposed in the removed pieces, the light-scattering particles are covered with the binder resin, so that the difference in refractive index from the binder resin existing around the light-scattering particles is large. Does not occur. Therefore, it is possible to determine whether or not a part of the surface of the light scattering particles is exposed by measuring the difference in refractive index with the binder resin existing around the light scattering particles by the Becke method or the like. .. In addition, the difference in refractive index between the binder resin and the light-scattering particles is measured using a phase-shift laser interference microscope (such as a phase-shift laser interference microscope manufactured by FK Optical Laboratory or a diketric interference microscope manufactured by Mizojiri Optical Co., Ltd.). can do.

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

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

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

The light-transmitting base materials 12 and 13 may be composed of a single base material, or may be a laminated base material composed of a plurality of base materials. Such a laminated base material may be composed of a plurality of layers composed of layers of the same type of constituent raw materials, or may be composed of a plurality of layers composed of layers of different types of constituent raw materials, depending on the intended use. Good.

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

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

The average particle size of the light-scattering particles in the light diffusing layers 14 and 15 is preferably 10 times or more and 20,000 times or less, and more preferably 10 to 5000 times the average particle size of the quantum dots 17 described above. preferable. If the average particle size of the light-scattering particles is less than 10 times the average particle size of the quantum dots, sufficient light diffusivity may not be obtained in the light-diffusing layer, and the average particle size of the light-scattering particles may not be sufficient. If it exceeds 20,000 times the average particle size of the quantum dots, the light diffusing performance of the light diffusing layer becomes excellent, but the light transmittance of the light diffusing layer tends to be significantly reduced. The average particle size of the light-scattering particles can be measured by the same method as the average particle size of the quantum dots described above.

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

The absolute value of the difference in refractive index between the light-scattering particles in the light diffusing layers 14 and 15 and the binder resin is preferably 0.02 or more and 0.15 or less. If it is less than 0.02, the light diffusivity due to the refractive index of the light scattering particles cannot be obtained optically, and the improvement of the light wavelength conversion efficiency of the light wavelength conversion sheet may be insufficient. If it exceeds 15, the transmittance of the light diffusion layer may decrease. The more preferable lower limit of the difference in refractive index between the light scattering particles and the binder resin is 0.03 or more, and the more preferable upper limit is 0.12 or less. Either the refractive index of the light-scattering particles or the refractive index of the binder resin may be larger. The refractive indexes of the light-scattering particles and the binder resin can be measured by the same method as the refractive indexes of the light-scattering particles 18 and the binder resin.

Since the shapes of the light-scattering particles in the light-diffusing layers 14 and 15 are the same as the shapes of the light-scattering particles 18 in the light wavelength conversion layer 11, the description thereof will be omitted here. The light-scattering particles in the light-diffusing layers 14 and 15 are preferably chemically bonded to the binder resin from the viewpoint of firmly fixing the light-scattering particles in the binder resin. This chemical bond can be realized by using light scattering particles surface-modified with a silane coupling agent. Since the silane coupling agent is the same as the silane coupling agent described in the section of light scattering particles in the light wavelength conversion composition, the description thereof will be omitted here.

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

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

<< Other optical wavelength conversion sheets >>
As shown in FIG. 3, the optical wavelength conversion sheet may be an optical wavelength conversion sheet 20 having only the optical wavelength conversion layer 11 (single layer structure). Further, as shown in FIG. 4, the light wavelength conversion sheet may be a light wavelength conversion sheet 30 including a light wavelength conversion layer 11 and a light transmissive base material 31 that supports the light wavelength conversion layer 11. .. By providing the light transmissive base material 31, the intensity of the light wavelength conversion sheet can be increased as compared with the light wavelength conversion sheet 20.

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

<< Other optical wavelength conversion sheets >>
As shown in FIGS. 5 and 6, the optical wavelength conversion sheet is arranged on at least one surface side of the optical wavelength conversion layer 11 and the optical wavelength conversion layer 11, and is integrated with the optical wavelength conversion layer 11. The optical wavelength conversion sheet 40 including the optical member 41 may be used.

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

As shown in FIGS. 5 and 6, the optical member 41 includes a light-transmitting base material 42 and a lens layer 43 provided on one surface of the light-transmitting base material 42. As shown in FIGS. 5 and 6, the lens layer 43 includes a sheet-shaped main body 44 and a plurality of unit lenses 45 arranged side by side on the light emitting side of the main body 44. The light transmissive base material 42, the lens layer 43, the main body portion 44, and the unit lens 45 have the same configurations as the light transmissive base material 101, the lens layer 102, the main body portion 103, and the unit lens 104, which will be described later. Therefore, the description thereof will be omitted here.

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

<< Other optical wavelength conversion sheets >>
As shown in FIG. 7, the optical wavelength conversion sheet may be an optical wavelength conversion sheet 50 including an optical wavelength conversion layer 11 and overcoat layers 51 and 52 covering both surfaces of the optical wavelength conversion layer 11. In the present embodiment, the overcoat layers 51 and 52 are formed on both sides of the light wavelength conversion layer 11, but if the overcoat layer is formed on at least one surface of the light wavelength conversion layer, the light wavelength conversion is performed. It does not have to be formed on both sides of the layer 11. When the overcoat layer is provided on only one surface of the light wavelength conversion layer, a light transmissive base material may be provided on the other surface of the light wavelength conversion layer.

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

The overcoat layers 51 and 52 are provided to prevent the light wavelength conversion layer 11 from being directly exposed to the atmosphere. By providing such overcoat layers 51 and 52 on at least one surface of the light wavelength conversion layer 11, the quantum dots 15 can be protected from moisture and oxygen, and the light transmissive base material can be provided as a light wavelength conversion layer. The thickness of the light wavelength conversion sheet can be made thinner than that provided on at least one surface of 11.

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

The film thickness of the overcoat layers 51 and 52 is 0.1 μm or more and 100 μm or less from the viewpoint of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere and thinning the light wavelength conversion sheet. Is preferable. The film thickness of the overcoat layer 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 preferably have a hardness of 10 μN or more in the vertical force and / or -5 μN or less in the horizontal force in the scratch test. When the overcoat layers 51 and 52 have such hardness, the overcoat layers 51 and 52 become a dense film, so that the ability to prevent the light wavelength conversion layer 11 from exposure to the atmosphere is high. The vertical force and horizontal force in the scratch test are indented (Cube) from the cross section of the overcoat layer to the inside of the overcoat layer using a nanoindentation device (product name "TI950 TriboIndenter", manufactured by HYSITRON). Corner: Ti037_110410 (12)) is pushed in by 50 nm, the depth is kept constant, and the average vertical force (load) and horizontal force measured when this indenter is moved horizontally at a moving speed of 4 μm / min for 30 seconds. The values were obtained respectively, and the average value of the five average values of the vertical force (5 times average value) and the average value of the five average values of the horizontal force (5 times average value) obtained by repeating this scratch test 5 times. And. The larger the value of the normal force and the smaller the value of the horizontal force, the higher the hardness of the overcoat layers 51 and 52. From the viewpoint of enhancing the ability to prevent the light wavelength conversion layer 11 from exposure to the atmosphere, the normal force of the overcoat layers 51 and 52 in the scratch test is more preferably 15 μN or more, and the horizontal force is more preferably -8 μN or less. preferable.

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

In the light wavelength conversion sheets 20, 30, 40, and 50, the light emission ratio of the incident light is 10% or more, as in the light wavelength conversion sheet 10. The light emission ratio of the incident light may be 20% or more.

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

<< Other optical wavelength conversion sheets >>
The optical wavelength conversion sheet may be an optical wavelength conversion sheet 60 as shown in FIG. In the light wavelength conversion sheet 60, the light emission ratio of the incident light is 10% or more, as in the light wavelength conversion sheet 10. The light emission ratio of the incident light may be 20% or more. Further, the water vapor transmittance and the oxygen transmittance of the light wavelength conversion sheet 60 do not have to be within the above-mentioned ranges.

The light wavelength conversion sheet 60 shown in FIG. 8 is the light wavelength conversion layer 11, the barrier members 61 and 62 provided on both sides of the light wavelength conversion layer 11, and the light wavelength conversion layer 11 side of the barrier members 61 and 62. It is provided with light diffusion layers 13 and 14 provided on the side opposite to the surface. In the light wavelength conversion sheet 60, the surfaces of the light diffusion layers 13 and 14 constitute the surfaces 60A and 60B of the light wavelength conversion sheet 60.

<Barrier member>
The barrier members 61 and 62 are members for suppressing the permeation of water and oxygen to protect the quantum dots 17 from water and oxygen. Here, the "barrier member" herein is a member alone, 40 ° C., water vapor transmission rate of 90% relative humidity becomes 0.1g ^/ (m 2 · 24h) below, and 23 ° C., relative humidity oxygen transmission rate at 90% is intended to mean a member made of a ^{0.1cm 3 / (m 2 · 24h} · atm) of less than. The barrier member includes not only a single-layer structure film but also a multi-layer structure film. By installing the barrier members 61 and 62 with the optical wavelength conversion layer 11 sandwiched between them, the durability of the quantum dots 17 can be further improved. The barrier members 61 and 62 shown in FIG. 8 are provided on the light transmissive base materials 12 and 13 and the light wavelength conversion layer 11 side of the light transmissive base materials 12 and 13, and suppress the permeation of water and oxygen. It includes barrier layers 63 and 64 having a function.

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

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

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

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

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

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

<<< Manufacturing method of optical wavelength conversion sheet >>>
The optical wavelength conversion sheet 10 can be produced, for example, as follows. First, although not shown, a light-diffusing layer composition containing light-scattering particles and a polymerizable compound is applied to one surface of the light-transmitting base material 12, dried, and then coated with the light-diffusing layer composition. Form a film. Similarly, a coating film of the composition for the light diffusion layer is formed on one surface of the light-transmitting base material 13.

Next, the coating film of the composition for the light diffusion layer is cured by light irradiation or the like. As a result, as shown in FIG. 9A, the light diffusing layer 14 is formed on one surface of the light transmitting base material 12, and the light transmitting base material 12 with the light diffusing layer 14 is formed. Further, although not shown, the light transmissive base material 13 with the light diffusing layer 15 is formed in the same manner.

After forming the light-transmitting base material 13 with the light-diffusing layer 15, as shown in FIG. 9B, the side of the light-transmitting base material 13 with the light-diffusing layer 15 opposite to the surface on the light-transmitting layer 15 side. The light wavelength conversion composition containing the quantum dots, the specific compound, and the polymerizable compound is applied to the surface of the light wavelength conversion composition and dried to form a coating film 19 of the light wavelength conversion composition.

After forming the coating film 19 of the light wavelength conversion composition, as shown in FIG. 10A, the surface of the light transmissive substrate 12 with the light diffusion layer 14 opposite to the surface on the light diffusion layer 14 side is the light wavelength. The light transmissive base material 12 with the light diffusing layer 14 is arranged on the coating film 19 of the light wavelength conversion composition so as to be in contact with the coating film 19 of the conversion composition. As a result, the coating film 19 of the light wavelength conversion composition is sandwiched between the light transmitting base materials 12 and 13.

Next, as shown in FIG. 10B, the coating film 19 of the light wavelength conversion composition is irradiated with ionizing radiation or heat is applied to cure the polymerizable compound via the light transmitting substrate 12. The light wavelength conversion layer 11 is formed, and the light wavelength conversion layer 11 is integrated with the light transmitting base material 12 with the light diffusing layer 14 and the light transmitting base material 13 with the light diffusing layer 15. As a result, the optical wavelength conversion sheet 10 shown in FIG. 1 is obtained.

The optical wavelength conversion sheets 20, 30 and 50 can be produced, for example, as follows. First, a light wavelength conversion composition containing quantum dots, the above-mentioned specific compound, and a polymerizable compound is applied onto a substrate (not shown) and dried to form a coating film of the light wavelength conversion composition. Then, the light wavelength conversion layer 11 is formed by irradiating the coating film with ionizing radiation or applying heat to cure the polymerizable compound. Then, the base material is peeled off from the light wavelength conversion layer 11. As a result, the optical wavelength conversion sheet 20 shown in FIG. 3 is obtained. On the other hand, when the light transmissive base material 31 is used as the base material, the light wavelength conversion sheet 30 shown in FIG. 4 can be obtained by leaving the base material as it is without peeling it from the light wavelength conversion layer 11. can get. In the light wavelength conversion sheet 50 shown in FIG. 7, the composition for the overcoat layer is applied to at least one surface of the light wavelength conversion sheet 20 to form a coating film of the composition for the overcoat layer, and this coating film is formed. Can be formed by curing. The light wavelength conversion sheet 50 can also be formed by the following method. First, the composition for the overcoat layer is applied to one surface of the two substrates to form a coating film of the composition for the overcoat layer. After forming the coating film, the coating film of each overcoat layer composition is irradiated with ionizing radiation or heated to form an overcoat layer. After forming the overcoat layer, the light wavelength conversion composition is applied onto the overcoat layer formed on one of the base materials to form a coating film of the light wavelength conversion composition. Next, the other base material is placed on the coating film of the light wavelength conversion composition so that the overcoat layer formed on the other base material is in contact with the coating film of the light wavelength conversion composition. Next, in this state, the coating film of the light wavelength conversion composition is irradiated with ionizing radiation or heat is applied to form a light wavelength conversion layer, and the light wavelength conversion layer and the overcoat layer are integrated. Let me. Finally, when both substrates are peeled off, the light wavelength conversion sheet 50 shown in FIG. 7 is obtained.

The light wavelength conversion sheet 40 is coated with the light wavelength conversion composition on one surface side of the optical member 41 and dried to form a coating film of the light wavelength conversion composition. Then, the light wavelength conversion layer 11 is formed by irradiating the coating film with ionizing radiation or applying heat to cure the polymerizable compound. As a result, the optical wavelength conversion sheet 40 shown in FIG. 5 is obtained.

The light wavelength conversion sheet 60 is a barrier in which the light diffusion layers 14 and 15 are provided with the light transmitting base materials 12 and 13 and the barrier layers 63 and 64 formed on one surface of the light transmitting base materials 12 and 13. If it is formed on the members 61 and 62, it can be formed by the same process as the light wavelength conversion sheet 10.

The optical wavelength conversion sheets 10, 20, 30, 40, 50, 60 can be used by being incorporated in a backlight device and an image display device. Hereinafter, an example in which the light wavelength conversion sheet 10 is incorporated into a backlight device and an image display device will be described. 11 is a schematic configuration diagram of an image display device including the backlight device according to the present embodiment, FIG. 12 is a perspective view of the lens sheet shown in FIG. 11, and FIG. 13 is a perspective view of the lens sheet of FIG. It is sectional drawing along line II. 14, 15, and 17 are schematic configuration diagrams of other backlight devices according to the present embodiment, FIG. 16 is a schematic configuration diagram of the light source shown in FIG. 15, and FIG. 18 is a schematic configuration diagram of the light source shown in FIG. It is an enlarged view near the light source surface of an optical plate.

<<< Image display device >>>
The image display device 70 shown in FIG. 11 includes a backlight device 80 and a display panel 120 arranged on the light emitting side of the backlight device 80. The image display device 70 has a display surface 70A for displaying an image. In the image display device 70 shown in FIG. 11, the surface of the display panel 120 is the display surface 70A.

The backlight device 80 illuminates the display panel 120 in a plane from the back side. The display panel 120 functions as a shutter that controls the transmission or blocking of light from the backlight device 80 for each pixel, and is configured to display an image on the display surface 70A.

<< Display panel >>
The display panel 120 shown in FIG. 11 is a liquid crystal display panel, and is between the polarizing plate 121 arranged on the incoming light side, the polarizing plate 122 arranged on the light emitting side, and the polarizing plate 121 and the polarizing plate 122. It includes an arranged liquid crystal cell 103. The polarizing plates 121 and 122 decompose the incident light into two orthogonal linearly polarized light components (S-polarized light and P-polarized light) and vibrate in one direction (direction parallel to the transmission axis) (for example, P). It has a function of transmitting polarized light) and absorbing a linearly polarized light component (for example, S-polarized light) that vibrates in the other direction (direction parallel to the absorption axis) orthogonal to the one direction.

The liquid crystal cell 123 is configured so that a voltage can be applied to each region forming one pixel. Then, the orientation direction of the liquid crystal molecules in the liquid crystal cell 123 changes depending on the presence or absence of voltage application. As an example, the linearly polarized light component in a specific direction transmitted through the polarizing plate 121 arranged on the incoming light side rotates its polarization direction by 90 ° when passing through the liquid crystal cell 123 to which a voltage is applied, while rotating the polarization direction by 90 °. When passing through the liquid crystal cell 123 to which no voltage is applied, the polarization direction is maintained. In this case, depending on whether or not a voltage is applied to the liquid crystal cell 123, the linearly polarized light component that vibrates in a specific direction that has passed through the polarizing plate 121 can be transmitted through the polarizing plate 122, or absorbed by the polarizing plate 122 and blocked. it can. In this way, the display panel 120 is configured so that the transmission or blocking of light from the backlight device 80 can be controlled for each pixel. The details of the liquid crystal display panel are described in various publicly known documents (for example, "Flat Panel Display Dictionary (supervised by Tatsuo Uchida and Hiraki Uchiike)" published by Kogyo Chosakai in 2001). The detailed description of is omitted.

<< Backlight device >>
The backlight device 80 shown in FIG. 11 is configured as an edge light type backlight device, and includes a light source 90, an optical plate 95 as a light guide plate arranged on the side of the light source 90, and a light emitting side of the optical plate 95. The optical wavelength conversion sheet 10 arranged in the light wavelength conversion sheet 10, the lens sheet 100 arranged on the light source side of the light wavelength conversion sheet 10, the lens sheet 105 arranged on the light source side of the lens sheet 100, and the light source side of the lens sheet 105. It includes a reflective polarizing separation sheet 110 arranged, and a reflective sheet 115 arranged on the side opposite to the light source side of the optical plate 95. The backlight device 80 includes an optical plate 95, lens sheets 100 and 105, a reflective polarizing separation sheet 110, and a reflective sheet 115, but these sheets and the like may not be provided. In the present specification, the “light emitting side” means the side of each member where light emitted in the direction of emission from the backlight device is emitted.

The backlight setting 80 has a light emitting surface 80A that emits light in a planar manner. In the backlight device 80 shown in FIG. 11, the light emitting surface of the reflective polarizing separation sheet 110 is the light emitting surface 80A of the backlight device 80.

The surface of the optical wavelength conversion sheet 10 on the optical plate 95 side is the surface 10A (light incoming surface), and the surface of the optical wavelength conversion sheet 10 on the lens sheet 100 side is the surface 10B (light emitting surface).

<Light source>
The light source 90 includes, for example, a fluorescent lamp such as a linear cold-cathode tube, or a light emitter such as a point-shaped light emitting diode (LED) or an incandescent light bulb. In the present embodiment, the light source 90 is composed of a large number of point-shaped light emitters arranged linearly on the light receiving surface 95C side of the optical plate 95, which will be described later, specifically, a large number of light emitting diodes (LEDs). ,It is configured.

Since the light wavelength conversion sheet 10 is arranged in the backlight device 80, the light source 90 can use only a light emitting body that emits light in a single wavelength range. For example, as the light source, only a blue light emitting diode that emits blue light having high color purity can be used.

<Optical plate>
The optical plate 95 as the light guide plate has a quadrangular shape in a plan view. The optical plate 95 extends between the light emitting surface 95A formed by one main surface on the display panel 120 side, the back surface 95B composed of the other main surface facing the light emitting surface 95A, and the light emitting surface 95A and the back surface 95B. Has sides. The side surface of the side surface on the light source 90 side is an incoming light receiving surface 75C that receives light from the light source 90. The light incident on the optical plate 95 from the light entry surface 95C is guided in the optical plate in the direction connecting the light entry surface 95C and the opposite surface facing the light entry surface 95C (light guide direction), and is guided through the optical plate. Emitted from 95A.

As a material constituting the optical plate 95, it is widely used as a material for an optical sheet incorporated in an image display device, has excellent mechanical properties, optical properties, stability, processability, etc., and is inexpensively available. For example, a transparent resin containing one or more of acrylic resin, polystyrene, polycarbonate, polyethylene terephthalate, polyacrylonitrile, etc. as a main component, and epoxy acrylate or urethane acrylate-based reactive resin (ionized radiation curable resin, etc.) are preferably used. Can be done. If necessary, a light diffusing material having a function of diffusing light can be added to the optical plate 75. As the light diffusing material, for example, particles made of a transparent substance such as silica (silicon dioxide), alumina (aluminum oxide), acrylic resin, polycarbonate resin, and silicone resin having an average particle diameter of 0.5 μm or more and 100 μm or less can be used. it can.

<< Lens sheet >>
The lens sheets 100 and 105 have a function of changing the traveling direction of the incident light and emitting the incident light from the light emitting side. In the present embodiment, as shown in FIG. 13, a function (condensing function) of changing the traveling direction of light L3 having a large incident angle and emitting it from the light emitting side to intensively improve the brightness in the front direction. At the same time, it has a function (retroreflection function) of reflecting light L4 having a small incident angle and returning it to the light wavelength conversion sheet 10 side. The lens sheets 100 and 105 include a light-transmitting base material 101 and a lens layer 102 provided on one surface of the light-transmitting base material 101.

When the surfaces 10A and 10B of the optical wavelength conversion sheet 10 are uneven surfaces, the light emitting surface 95A of the optical plate 95 is optically in close contact with a part (for example, a convex portion) of the surface 10A, and is also a surface. It is preferable that the lens sheet 100 is separated from other parts (for example, concave parts) of 10A, and the light entering surface 100A of the lens sheet 100 is optically in close contact with a part (for example, convex parts) of the surface 10B and also has a surface. It is preferable that the 10B is separated from other parts (for example, recesses). In this case, the gap between the light emitting surface 95A and the other part of the surface 10A and the gap between the light entering surface 100A and the other part of the surface 10B are an air layer. By providing this air layer, the light wavelength conversion sheet 10, the optical plate 95, and the lens sheet 100 are fixed so that the light emitting surface 95A and the surface 10A and the light entering surface 100A and the surface 10B are in optical contact with each other. However, since it is possible to prevent the light wavelength conversion sheet 10 from sticking to the optical plate 95 and the lens sheet 100, the interface between the light wavelength conversion sheet 10 and the optical plate 95 and the light wavelength conversion sheet 10 and the lens sheet 100 It is possible to suppress the formation of wet-out at the interface between the light and the light.

<Light transmissive base material>
Since the light-transmitting base material 101 is the same as the light-transmitting base materials 12 and 13, the description thereof will be omitted here.

<Lens layer>
As shown in FIGS. 12 and 13, the lens layer 102 includes a sheet-shaped main body 103 and a plurality of unit lenses 104 arranged side by side on the light emitting side of the main body 103.

The main body 103 functions as a sheet-like member that supports the unit lens 104. As shown in FIGS. 12 and 13, unit lenses 104 are arranged on the light emitting side surface 103A of the main body 103 without leaving a gap. Therefore, the light emitting surfaces 100B and 105B of the lens sheets 100 and 105 are formed by the lens surfaces. On the other hand, as shown in FIG. 13, the main body 103 has a smooth surface forming the incoming side surface of the lens layer 102 as the incoming light entering side surface 103B facing the light emitting side surface 103A.

The unit lenses 104 are arranged side by side on the light emitting side surface 103A of the main body 103. As shown in FIG. 12, the unit lens 104 extends linearly in a direction intersecting the arrangement direction AD of the unit lens 104, particularly linearly in the present embodiment. Further, in the present embodiment, a large number of unit lenses 104 included in one lens sheet 100 and 105 extend in parallel with each other. Further, the longitudinal LD of the unit lenses 104 of the lens sheets 100 and 105 is orthogonal to the arrangement direction AD of the unit lenses 104 of the lens sheets 100 and 105.

The unit lens 104 may have a triangular columnar shape, or may have a wavy shape or a bowl shape such as a hemispherical shape. Specifically, examples of the unit lens include a unit prism, a unit cylindrical lens, a unit microlens, and the like. Examples of the lens sheet having such a unit lens shape include a prism sheet, a lenticular lens sheet, and a microlens sheet. In the present embodiment, as a unit lens, a triangular columnar unit prism whose width becomes narrower toward the light emitting side will be described. The shape of the cross section (also called the main cut surface of the lens sheet) parallel to both the normal direction ND of the sheet surfaces of the lens sheets 100 and 105 and the arrangement direction AD of the unit lens 104 is a triangular shape protruding toward the light emitting side. ing. In particular, from the viewpoint of intensively improving the brightness in the front direction, the cross-sectional shape of the unit lens 104 on the main cutting surface is an isosceles triangle shape, and the apex angle located between the equilateral sides is the light emitting side surface 103A of the main body 103. Each unit lens 104 is configured so as to project from the light emitting side.

From the viewpoint of improving the efficiency of light utilization, the unit lens 104 preferably has an apex angle of 80 ° or more and 100 ° or less, and more preferably about 90 °. However, considering the damage to the tip of the unit lens when winding the optical wavelength conversion sheet, the tip of the unit lens 104 may be a curved surface.

The dimensions of the lens sheets 100 and 105 can be set as follows, for example. First, as a specific example of the unit lens 104, the arrangement pitch of the unit lens 104 (corresponding to the width of the unit lens 104 in the illustrated example) can be set to 10 μm or more and 200 μm or less. However, in recent years, the arrangement of the unit lens 104 has been rapidly improved in definition, and it is preferable that the arrangement pitch of the unit lens 104 is 10 μm or more and 50 μm or less. Further, the protruding height of the unit lens 104 from the main body 103 along the normal direction ND of the lens sheets 100 and 105 to the sheet surface can be set to 5 μm or more and 100 μm or less. Further, the apex angle θ of the unit lens 104 can be set to 60 ° or more and 120 ° or less.

As can be understood from FIG. 11, the arrangement direction of the unit lens 104 of the lens sheet 100 and the arrangement direction of the unit lens 104 of the lens sheet 105 intersect, and more specifically, are orthogonal to each other.

<Reflective polarization separation sheet>
The reflective polarization separation sheet 110 transmits only the first linearly polarized light component (for example, P-polarized light) among the light emitted from the lens sheet 105, and is a second straight line orthogonal to the first linearly polarized light component. It has a function of reflecting polarized light components (for example, S-polarized light) without absorbing them. The second linearly polarized light component reflected by the reflective polarization separation sheet 110 is reflected again, and the polarized light is eliminated (a state in which both the first linearly polarized light component and the second linearly polarized light component are included). It is incident on the reflective polarizing separation sheet 110 again. Therefore, the reflective polarization separation sheet 110 transmits the first linearly polarized light component of the light incident again, and the second linearly polarized light component orthogonal to the first linearly polarized light component is reflected again. Hereinafter, by repeating the same process, about 70 to 80% of the light emitted from the lens sheet 105 is emitted as the light source light which is the first linearly polarized light component. Therefore, by matching the polarization direction of the first linearly polarized light component (transmission axis component) of the reflective polarization separation sheet 110 with the transmission axis direction of the polarizing plate 121 of the display panel 120, the light emitted from the backlight device 80 Are all available for image formation on the display panel 120. Therefore, even if the light energy input from the light source 90 is the same, it is possible to form an image with higher brightness than when the reflective polarizing separation sheet 110 is not arranged, and the energy utilization efficiency of the light source 90 is also improved. improves. In particular, the light reflected by the reflective polarizing separation sheet 110 can be wavelength-converted by the optical wavelength conversion sheet 10. Therefore, by arranging the reflective polarizing separation sheet 110, the wavelength conversion efficiency of the optical wavelength conversion sheet 10 can be further increased. Therefore, further improvement in light utilization efficiency can be expected.

As the reflective polarizing separation sheet 110, "DBEF" (registered trademark) available from 3M can be used. In addition to "DBEF", a high-intensity polarizing sheet "WRPS" available from Shinwha Intertek, a wire grid polarizer, or the like can be used as the reflective polarizing separation sheet 90.

<Reflective sheet>
The reflective sheet 115 has a function of reflecting the light leaked from the back surface 95B of the optical plate 95 and causing it to enter the optical plate 90 again. The reflective sheet 115 is composed of a white diffuse reflective sheet, a sheet made of a material having a high reflectance such as metal, a sheet containing a thin film made of a material having a high reflectance (for example, a metal thin film) as a surface layer, and the like. obtain. The reflection on the reflective sheet 115 may be regular reflection (specular reflection) or diffuse reflection. When the reflection on the reflection sheet 115 is diffuse reflection, the diffuse reflection may be isotropic diffuse reflection or anisotropic diffuse reflection.

<< Other backlight devices >>
The backlight device incorporating the optical wavelength conversion sheet 10 may be a direct type backlight device as shown in FIG. The backlight device 130 shown in FIG. 14 includes a light source 90, an optical plate 131 that receives the light of the light source 90 and functions as a light diffusing plate, and an optical wavelength conversion sheet 10 arranged on the light emitting side of the optical plate 131. The lens sheet 100 arranged on the light emitting side of the optical wavelength conversion sheet 10, the lens sheet 105 arranged on the light emitting side of the lens sheet 100, and the reflective polarization separation sheet 110 arranged on the light emitting side of the lens sheet 105. I have. In the present embodiment, the light source 90 is arranged directly below the optical plate 131, not on the side of the optical plate 131. In FIG. 14, the members having the same reference numerals as those in FIG. 11 are the same as the members shown in FIG. 11, and thus the description thereof will be omitted. The backlight device 130 is not provided with the reflective sheet 115.

<Optical plate>
The optical plate 131 as a light diffusing plate has a quadrangular shape in a plan view. The optical plate 131 has an incoming light receiving surface 131A formed by one main surface on the light source 95 side and an outgoing light emitting surface 131B formed by the other main surface on the light wavelength conversion sheet 10. The light incident on the optical plate 131 from the light incoming surface 131A is diffused in the optical plate 131 and emitted from the light emitting surface 131B.

The optical plate 131 is not particularly limited as long as it can diffuse the light from the light source 90, and examples thereof include a plate in which light diffusing particles are dispersed in a transparent material. The transparent material is not particularly limited, and examples thereof include transparent resin and inorganic glass. As the transparent resin, a transparent thermoplastic resin is preferably used because it is easy to mold. The transparent thermoplastic resin is not particularly limited, but for example, a polystyrene resin, a styrene-methyl methacrylate copolymer resin, a styrene-methacrylate copolymer resin, and a styrene-maleic anhydride copolymer resin. , Methacrylic resin, acrylic resin, polycarbonate resin, ABS resin (acrylonitrile-butadiene-styrene copolymer resin), AS resin (acrylonitrile-styrene copolymer resin), polyolefin resin (polyethylene resin, polypropylene resin, etc.) and the like. .. One of these may be used, or two or more of these may be mixed and used.

<Light diffusing particles>
Examples of the light diffusing particles in the optical plate 131 include light diffusing particles generally used as a diffusing plate.

<< Other backlight devices >>
The backlight device 80 shown in FIG. 11 includes an optical wavelength conversion sheet 10, but the structure of the backlight device is not particularly limited as long as it includes an optical wavelength conversion member. For example, as shown in FIG. 15, the backlight device may be a backlight device 140 including a light source 150 instead of the light wavelength conversion sheet 10 and the light source 90. As shown in FIG. 16, the light source 150 has a substrate 151, a reflection member 152 having an opening 152A arranged on the substrate 151, and a light emitting member arranged on the substrate 151 and in the opening 152A of the reflection member 152. A light source 153 such as a diode and a light wavelength conversion member 154 filled in the opening 152A of the reflection member 152 so as to cover the light source 153 are provided. The light wavelength conversion member 154 is different from the light wavelength conversion layer 11 in shape and arrangement, and the configuration and physical properties of the light wavelength conversion member 154 are the same as those of the light wavelength conversion layer 11. Therefore, the description thereof will be omitted here. And. The light wavelength conversion member 154 can be formed by filling the opening 152A of the reflection member 152 with the light wavelength conversion composition and curing it. When the light source 150 having the light wavelength conversion member 154 is used, the structure is not particularly limited as long as the light wavelength conversion member 154 is arranged so as to cover the light emitting body 153.

<< Other backlight devices >>
The backlight device may be the backlight device 160 shown in FIG. Specifically, the backlight device 160 shown in FIG. 17 includes a light wavelength conversion layer 170 arranged between the light source 90 and the optical plate 95 instead of the light wavelength conversion sheet 10. The light wavelength conversion layer 170 shown in FIG. 17 is provided on the light incoming surface 95C of the optical plate 95. The optical wavelength conversion layer 170 is different from the optical wavelength conversion layer 11 only in the arrangement location, and the configuration and physical properties of the optical wavelength conversion layer 170 are the same as those of the optical wavelength conversion member 11. Therefore, the description thereof will be omitted here. .. The light wavelength conversion layer 170 can be formed by applying the above light wavelength conversion composition to the light input surface 95C of the optical plate 95 and curing it.

It is considered that the reason why quantum dots are easily deteriorated by the heat resistance test, the moist heat resistance test and the light resistance test is as follows. First, a ligand composed of a sulfur-based compound, a phosphorus-based compound, or the like is coordinated on the surface of the quantum dot, and this ligand is easily desorbed by light or heat. When the ligand is desorbed from the quantum dots, water and oxygen are likely to adhere to the quantum dots, so that the quantum dots are oxidized and deteriorated. As a result, it is considered that the quantum dots are deteriorated by the heat resistance test, the moist heat resistance test, and the light resistance test. On the other hand, in the present embodiment, since the light wavelength conversion composition and the light wavelength conversion layer 11 contain the above-mentioned specific compound, oxygen existing in the light wavelength conversion composition and the light wavelength conversion layer 11 It can capture radicals and singlet oxygen. That is, the specific compound functions as an antioxidant. As a result, deterioration of the quantum dots 17 due to oxidation can be suppressed, so that the heat resistance, moisture heat resistance, and light resistance of the light wavelength conversion composition, the light wavelength conversion layer 11, and the light wavelength conversion sheet 10 can be improved. Can be done.

When the specific compound absorbs the light incident on the light wavelength conversion sheet, the amount of light applied to the quantum dots is reduced by that amount, so that the luminous efficiency is lowered. On the other hand, in the present embodiment, the light emission ratio of the incident light in the light wavelength conversion sheets 10, 20, 30, 40, 50, 60 is 10% or more. This means that the light incident on the light wavelength conversion sheets 10, 20, 30, 40, 50, 60 is less likely to be absorbed by the specific compound. Therefore, according to the light wavelength conversion sheets 10, 20, 30, 40, 50, and 60, excellent heat resistance, moisture heat resistance, and light resistance can be obtained while suppressing a decrease in luminous efficiency.

According to the present embodiment, the deterioration of the quantum dots 17 can be suppressed by the optical wavelength conversion layer 11 containing the specific compound. Therefore, in the optical wavelength conversion sheets 10, 20, 30, 40, 50, 60, the barrier member is used. It can be omitted, and even when a barrier member is used, it is possible to suppress a point-shaped brightness defect. That is, in the light wavelength conversion sheets 10, 20, 30, 40, 50, the deterioration of the quantum dots 17 can be suppressed by the light wavelength conversion layer 11 containing the specific compound, so that the barrier member can be omitted. Further, in the optical wavelength conversion sheet 60 provided with the barrier members 61 and 62, the deterioration of the quantum dots 17 can be suppressed by the optical wavelength conversion layer 11 containing the specific compound, so that even if the barrier members 61 and 62 are used, the barrier members 61 and 62 may be used. Even when pinholes or cracks occur and moisture or oxygen enters through the pinholes or cracks, the point-like brightness defect can be suppressed. Further, since the deterioration of the quantum dots 17 can be suppressed by the specific compound existing in the light wavelength conversion layer 11, the peripheral portions 10C, 20C, 30C of the light wavelength conversion sheets 10, 20, 30, 40, 50, 60 , 40C, 50C, 60C can also suppress the deterioration of the quantum dots 17.

In the optical wavelength conversion sheets 10, 20, 30, 40, and 50, the barrier member is not provided because the deterioration of the quantum dots 17 can be suppressed by the specific compound present in the optical wavelength conversion layer 11. As a result, the process of the optical wavelength conversion sheet can be simplified, so that the quality can be easily improved and the optical wavelength conversion sheet can be made thinner.

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

A light emitting body such as a light emitting diode also emits heat when it emits light. Therefore, normally, when the light wavelength conversion member is incorporated in the light source or when the light wavelength conversion member is arranged at a position close to the light source, the light wavelength conversion member is covered in order to suppress the deterioration of the quantum dots. A barrier member is required. On the other hand, in the present embodiment, the above-mentioned specific compound present in the light wavelength conversion member 154 and the light wavelength conversion layer 170 improves the moist heat resistance and heat resistance of the light wavelength conversion member 154 and the light wavelength conversion layer 170. Therefore, deterioration of the quantum dot 17 can be suppressed without covering the light wavelength conversion member 154 and the light wavelength conversion layer 170 with the barrier member. Thereby, the light wavelength conversion member 154 can be incorporated into the light source 150, or the light wavelength conversion layer 170 can be arranged at a position close to the light source 90.

Conventionally, light that has been wavelength-converted by quantum dots emitted from the light wavelength conversion sheet is condensed on the light emitting side of the light wavelength conversion sheet, and light that has not been wavelength-converted by the light wavelength conversion sheet is collected by the light wavelength conversion sheet. It is being studied to improve the light wavelength conversion efficiency by arranging a lens sheet to be returned to the side. However, the light wavelength conversion efficiency is not sufficient only by arranging such a lens sheet, and further improvement of the light wavelength conversion efficiency is desired. According to the present embodiment, when the external haze value of the light wavelength conversion sheet 10 is smaller than the internal haze value of the light wavelength conversion sheet 10, the light wavelength conversion efficiency can be further improved. That is, since the light emitted from the light source has straightness, the light that enters the light wavelength conversion sheet and emits the light wavelength conversion sheet without being wavelength-converted by the quantum dots also has straightness. There is. Here, when the external haze value of the optical wavelength conversion sheet is high, the non-wavelength-converted light having straightness on the surface of the optical wavelength conversion sheet is refracted, and in the unconverted wavelength light emitted from the optical wavelength conversion sheet. Has a large number of components with a large emission angle. On the other hand, a lens sheet having a condensing function and a retroreflective function tends to retroreflect the lens sheet as the incident angle on the lens sheet is smaller. That is, the larger the angle of incidence on the lens sheet, the easier it is for the light to pass through the lens sheet. In the present embodiment, in the light wavelength conversion sheet 10, the external haze value is smaller than the internal haze value, so that even if the light that has not been wavelength-converted on the surface of the light wavelength conversion sheet 10 is refracted, it is emitted. It can be emitted in a state where the angle is small, and thus it is possible to increase the number of components having a small emission angle in the unwavelength-converted light emitted from the optical wavelength conversion sheet 10. Therefore, the lens sheet 100 can retroreflect the light emitted from the light wavelength conversion sheet without wavelength conversion and return it to the light wavelength conversion sheet 10 side, so that the opportunity for wavelength conversion increases. Further, since the internal haze value is larger than the external haze value, the optical path length is extended by scattering the light a plurality of times inside the optical wavelength conversion sheet, and the chance of wavelength conversion is further increased. Thereby, the light wavelength conversion efficiency can be improved. Since the quantum dots 17 emit light isotropically, the light wavelength-converted by the quantum dots 17 is oriented in various directions, and when the light reaches the surface of the optical wavelength conversion sheet 10, the surface of the optical wavelength conversion sheet is further reached. The light is refracted at, and the wavelength-converted light becomes light having a large angle and is easily emitted from the light wavelength conversion sheet. Therefore, the wavelength-converted light is relatively easy to pass through the lens sheet 100.

In the above, the light diffusion characteristic (external diffusion characteristic) on the surface of the light wavelength conversion sheet is expressed by using the external haze value for the following reasons. First, the light diffusion characteristics of the light wavelength conversion sheet can be evaluated by measuring the light intensity of the transmitted light for each angle with a known variable luminosity meter such as a goniophotometer. It is extremely difficult to define the light diffusion characteristics of the light wavelength conversion sheet using the light intensity results. On the other hand, as described above, in the definition of haze, transmitted light deviated by 2.5 ° or more with respect to incident light is measured as haze, but transmitted light less than 2.5 ° with respect to incident light is measured as haze. Not measured. As described above, the transmitted light having a haze of less than 2.5 ° with respect to the incident light is not measured, but as described above, the light having a large incident angle to the lens sheet, that is, the transmitted light having a large emission angle in the optical wavelength conversion sheet is emitted. Since it is a problem, it is important how much transmitted light exists that deviates by 2.5 ° or more from the transmitted light that is less than 2.5 ° with respect to the incident light. Therefore, the light diffusion characteristic of the light wavelength conversion sheet can be expressed by the magnitude of the haze value of the light wavelength conversion sheet without measuring the light intensity for each angle of transmitted light by the angle-changing photometer. On the other hand, it is necessary to consider that the light is refracted on the surface of the light wavelength conversion sheet and the emission angle becomes large. Therefore, in order to express the light diffusion characteristics on the surface of the light wavelength conversion sheet, an external haze is required. The value was used.

According to the present embodiment, since the light wavelength conversion layer 11 contains the light scattering particles 18, the light wavelength conversion efficiency can be further improved. Therefore, for example, a light source that emits blue light is used as the light source 90, a quantum dot that converts blue light into green light is used as the first quantum dot 17A, and blue light is converted into red light as the second quantum dot 17B. When a light wavelength conversion sheet containing quantum dots is irradiated with blue light, the chromaticity x and y can be increased as compared with the light wavelength conversion sheet not containing light-scattering particles, and the color is white light or a color close to white. You can get the light of taste.

According to the present embodiment, since the light wavelength conversion layer 11 contains the light scattering particles 18, the green light emission can be preferentially enhanced over the red light emission. The reason for this is not clear, but light-scattering particles may impede energy transfer from the first quantum dot that converts blue light to green light to the second quantum dot that converts blue light to red light. It is considered that this is because the green light emission, which was originally deactivated by the above energy transfer, reaches the light emission process without being deactivated, and as a result, the green light emission increases.

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

<Preparation of optical wavelength conversion composition>
First, each component was blended so as to have the composition shown below to obtain an optical wavelength conversion composition.
(Light wavelength conversion composition 1)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 99 parts by mass-stearyl β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (product name "IRGANOX1076", BASF): 1 part by mass, green emission quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts 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): 0.2 parts by mass-Radical polymerization initiator (1- Hydroxycyclohexylphenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 2)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 99 parts by mass-Stearyl β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (product name "IRGANOX1076", BASF): 1 part by mass, green emission quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass -Red emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm): 0.2 parts by mass-Alumina particles (light scattering particles) , Product name "DAM-03", manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 4 μm): 10 parts by mass, radical polymerization initiator (1-hydroxycyclohexylphenylketone, product name "Irgacure (registered trademark) 184", BASF Japan (Manufactured by): 0.2 parts by mass

(Light wavelength conversion composition 3)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 90 parts by mass-stearyl β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (product name "IRGANOX1076", BASF): 10 parts by mass, green emission quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts 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): 0.2 parts by mass-Radical polymerization initiator (1- Hydroxycyclohexylphenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 4)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 99.9 parts by mass-stearyl β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (product name "IRGANOX1076") , BASF): 0.1 parts by mass, green emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0 .2 parts by mass, red emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm): 0.2 parts by mass, start of radical polymerization Agent (1-hydroxycyclohexylphenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 5)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 99 parts by mass · 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate (product) Name "IRGANOX3114", manufactured by BASF): 1 part by mass, green emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass, red emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm): 0.2 parts by mass, radical polymerization Initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 6)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 99 parts by mass-Tetrax [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane (product Name "IRGANOX3114", manufactured by BASF): 1 part by mass, green emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass, red emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm): 0.2 parts by mass, radical polymerization Initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 7)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 99 parts by mass- (Mixed 1,2,2,6,6-pentamethyl-4-piperidyl / tridecyl) -1,2,3 , 4-Butan tetracarboxylate (product name "LA-52", manufactured by ADEKA): 1 part by mass, green emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell : ZnS, average particle size 3.3 nm): 0.2 parts by mass, red emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5. 2 nm): 0.2 parts by mass ・ Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name “Irgacure (registered trademark) 184”, manufactured by BASF Japan): 0.2 parts by mass

(Light wavelength conversion composition 8)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 99 parts by mass- (Mixed 1,2,2,6,6-pentamethyl-4-piperidyl / tridecyl) -1,2,3 , 4-Butan tetracarboxylate (product name "LA-52", manufactured by ADEKA): 1 part by mass, green emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell : ZnS, average particle size 3.3 nm): 0.2 parts by mass, red emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5. 2 nm): 0.2 parts by mass ・ Alumina particles (light scattering particles, product name “DAM-03”, manufactured by Denki Kagaku Kogyo Co., Ltd., average particle diameter 4 μm): 10 parts by mass ・ Radical polymerization initiator (1-hydroxycyclohexyl) Phenylketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan): 0.2 parts by mass

(Light wavelength conversion composition 9)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 90 parts by mass- (Mixed 1,2,2,6,6-pentamethyl-4-piperidyl / tridecyl) -1,2,3 , 4-Butan tetracarboxylate (product name "LA-52", manufactured by ADEKA): 10 parts by mass, green emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell : ZnS, average particle size 3.3 nm): 0.2 parts by mass, red emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5. 2 nm): 0.2 parts by mass ・ Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name “Irgacure (registered trademark) 184”, manufactured by BASF Japan): 0.2 parts by mass

(Light wavelength conversion composition 10)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 99.9 parts by mass- (Mixed 1,2,2,6,6-pentamethyl-4-piperidyl / tridecyl) -1,2 , 3,4-Butan tetracarboxylate (product name "LA-52", manufactured by ADEKA): 0.1 parts by mass, green emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core : CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass, red emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average Particle size 5.2 nm): 0.2 parts by mass ・ Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name “Irgacure (registered trademark) 184”, manufactured by BASF Japan): 0.2 parts by mass

(Light wavelength conversion composition 11)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 99 parts by mass-bis (2,2,6,6-tetramethyl-4-piperidyl) selenide (product name "LA-72", ADEKA): 1 part by mass, green emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts 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): 0.2 parts by mass-Radical polymerization initiator (1- Hydroxycyclohexylphenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan): 0.2 parts by mass

(Light wavelength conversion composition 12)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 99 parts by mass-methacrylate 1,2,2,6,6-pentamethyl-4-piperidyl (product name "LA-82", ADEKA (Manufactured by): 1 part by mass ・ Green emission quantum dots (product name “CdSe / ZnS 530”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts 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): 0.2 parts by mass, radical polymerization initiator (1-hydroxy) Cyclohexylphenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan): 0.2 parts by mass

(Light wavelength conversion composition 13)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 100 parts by mass-Green emission quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS , Average particle size 3.3 nm): 0.2 parts by mass, red emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm) : 0.2 parts by mass ・ Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name “Irgacure (registered trademark) 184”, manufactured by BASF Japan): 0.2 parts by mass

(Light wavelength conversion composition 14)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 99 parts by mass-Bechenic acid amide (manufactured by Tokyo Kasei Kogyo Co., Ltd.): 1 part by mass-Green light emitting quantum dots (product name "CdSe / ZnS 530") , SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass, red emission quantum dots (product name "CdSe / ZnS 610", SIGMA-ALDRICH, Core: CdSe, Shell: ZnS, Average particle size 5.2 nm): 0.2 parts by mass ・ Radical polymerization initiator (1-hydroxycyclohexylphenylketone, product name “Irgacure (registered trademark) 184”, manufactured by BASF Japan) : 0.2 parts by mass

(Light wavelength conversion composition 15)
-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 99 parts by mass-4-phenylbenzoyl hydrazine (manufactured by Tokyo Kasei Kogyo Co., Ltd.): 1 part by mass-green emission quantum dots (product name "CdSe /" ZnS 530 ", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass, red emission quantum dots (product name" CdSe / ZnS 610 ", SIGMA-ALDRICH" , Core: CdSe, Shell: ZnS, Average particle size 5.2 nm): 0.2 parts by mass ・ Radical polymerization initiator (1-hydroxycyclohexylphenylketone, product name “Irgacure (registered trademark) 184”, BASF Japan, Inc. Made): 0.2 parts by mass

<Preparation of composition for overcoat layer>
Each component was blended so as to have the composition shown below to obtain a composition for an overcoat layer.
(Composition 1 for overcoat layer)
-Zinc acrylate (product name "ZN-DA" manufactured by Nippon Catalyst Co., Ltd.): 30 parts by mass-Methanol: 70 parts by mass-Photopolymerization initiator (1-hydroxycyclohexylphenylketone, product name "Irgacure (registered trademark) 184," BASF Japan): 1 part by mass

(Composition for overcoat layer 2)
-A mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (product name "Aronix (registered trademark) M-403", manufactured by Toa Synthetic Co., Ltd.): 30 parts by mass-Methanol: 70 parts by mass-Photopolymerization initiator (1) -Hydroxycyclohexylphenylketone, product name "Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.): 1 part by mass

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

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

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

<Examples 2 to 12>
In Examples 2 to 12, an optical wavelength conversion sheet was produced in the same manner as in Example 1 except that each optical wavelength conversion composition shown in Table 1 was used instead of the optical wavelength conversion composition 1. ..

<Example 13>
The light wavelength conversion composition 1 was applied to one surface of a 50 μm-thick polyethylene terephthalate (PET) substrate (product name “Lumilar T60”, manufactured by Toray Industries, Inc.) and dried at 80 ° C. to form a coating film. .. Then, the coating film was cured by irradiating with ultraviolet rays so that the integrated light amount was 500 mJ / cm ^2. Finally, the PET substrate was peeled off to obtain an optical wavelength conversion sheet composed of only an optical wavelength conversion layer having a film thickness of 100 μm according to Example 13.

<Example 14>
In Example 14, a light wavelength conversion sheet was produced in the same manner as in Example 13 except that the light wavelength conversion composition 7 was used instead of the light wavelength conversion composition 1.

<Example 15>
The composition 1 for the overcoat layer was applied to one surface of the light wavelength conversion sheet (light wavelength conversion layer) produced in Example 13 to form a coating film. Then, ultraviolet rays were irradiated so that the integrated light intensity was 500 mJ / cm ² , and the coating film was cured to obtain an overcoat layer having a film thickness of 5 μm. Next, in the same manner, the composition 1 for the overcoat layer was applied to the other surface of the light wavelength conversion layer to form a coating film. Then, ultraviolet rays were irradiated so that the integrated light intensity was 500 mJ / cm ² , and the coating film was cured to obtain an overcoat layer having a film thickness of 5 μm. As a result, an optical wavelength conversion sheet composed of an optical wavelength conversion layer and an overcoat layer formed on both sides of the optical wavelength conversion layer was obtained.

<Example 16>
In Example 16, an optical wavelength conversion sheet was produced in the same manner as in Example 15 except that the composition 2 for the overcoat layer was used instead of the composition 1 for the overcoat layer.

<Example 17>
In Example 17, a light wavelength conversion sheet was produced in the same manner as in Example 15 except that the light wavelength conversion composition 7 was used instead of the light wavelength conversion composition 1.

<Example 18>
A prism layer composition containing urethane acrylate is uniformly applied to one surface of a 100 μm-thick polyethylene terephthalate (PET) substrate (product name “Lumilar T60”, manufactured by Toray Industries, Inc.) to form a prism layer composition. A coating film was formed to form a laminate for a prism sheet. Then, the traveling speed of the prism sheet laminate is such that the coating film of the lens layer composition is on the molding die side in the rotating molding die having a recess having an inverted shape with respect to the desired unit prism shape. The shape of the unit prism is formed on the coating film of the prism layer composition by supplying at 20 m / min with a molding die, and light such as ultraviolet rays is applied to the coating film of the prism layer composition via the PET substrate. Irradiation was performed to cure the coating film of the composition for the prism layer. Finally, the cured coating film of the prism layer composition was peeled off from the molding mold together with the PET base material to obtain a prism sheet having a prism layer formed on one surface of the PET base material. The prism layers are arranged side by side on the sheet-shaped main body and each of them extends in a direction intersecting the arrangement direction, the apex angle is 90 °, the width is 47 μm, and the height is high. It had a plurality of triangular columnar unit prisms having a height of 30 μm.

Next, the light wavelength conversion composition 1 was applied to the surface of the prism sheet opposite to the surface of the PET substrate on the side opposite to the prism layer side, and dried at 80 ° C. to form a coating film. Then, the coating film was cured by irradiating ultraviolet rays so that the integrated light amount was 500 mJ / cm ² , to form an optical wavelength conversion layer having a film thickness of 100 μm integrated with the prism sheet. As a result, the optical wavelength conversion sheet according to Example 18 was obtained.

<Example 19>
In Example 19, a light wavelength conversion sheet was produced in the same manner as in Example 18 except that the light wavelength conversion composition 7 was used instead of the light wavelength conversion composition 1.

<Example 20>
First, two barrier members were produced by the following method. In a high-frequency sputtering apparatus, polyethylene terephthalate as a light-transmitting substrate having a size of 7 inches and a thickness of 50 μm is generated by applying a high-frequency power of 13.56 MHz and a power of 5 kW to the electrodes to generate an electric discharge in the chamber. A silica-deposited layer made of a target substance (silica), having a thickness of 50 nm and a refractive index of 1.46, was formed on one side of a (PET) base material (product name “Lumilar T60”, manufactured by Toray Co., Ltd.). As a result, two barrier members having a silica-deposited layer formed on one surface of the PET base material were formed.

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

Next, the light wavelength conversion composition 1 was applied to the silica-deposited layer side of one of the barrier members with a light diffusion layer and dried at 80 ° C. to form a coating film. Then, the other barrier member with a light diffusion layer was laminated on the surface of the silica-deposited layer of the barrier member with a light diffusion layer in the coating film so that the silica vapor deposition layer was in contact with the surface. In this state, by irradiating the coating film with ultraviolet rays so that the integrated light amount is 500 mJ / cm ² , a light wavelength conversion layer having a thickness of 100 μm is formed in close contact with both barrier members with light diffusion layers. did. As a result, the optical wavelength conversion sheet according to Example 20 was obtained.

<Example 21>
In Example 21, a light wavelength conversion sheet was produced in the same manner as in Example 20 except that the light wavelength conversion composition 7 was used instead of the light wavelength conversion composition 1.

<Comparative Examples 1 to 3>
In Comparative Example 1, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that each light wavelength conversion composition shown in Table 2 was used instead of the light wavelength conversion composition 1.

<Comparative Examples 4 to 6>
In Comparative Examples 4 to 6, an optical wavelength conversion sheet was produced in the same manner as in Example 13 except that each optical wavelength conversion composition shown in Table 2 was used instead of the optical wavelength conversion composition 1. ..

<Comparative Examples 7-9>
In Comparative Examples 7 to 9, an optical wavelength conversion sheet was produced in the same manner as in Example 15 except that each optical wavelength conversion composition shown in Table 2 was used instead of the optical wavelength conversion composition 1. ..

<Comparative Examples 10 to 12>
In Comparative Examples 10 to 12, an optical wavelength conversion sheet was produced in the same manner as in Example 18 except that each optical wavelength conversion composition shown in Table 2 was used instead of the optical wavelength conversion composition 1. ..

<Comparative Examples 13 to 15>
In Comparative Examples 13 to 15, an optical wavelength conversion sheet was produced in the same manner as in Example 20 except that each optical wavelength conversion composition shown in Table 2 was used instead of the optical wavelength conversion composition 1. ..

<Measurement of emission ratio of incident light (blue light)>
In the optical wavelength conversion sheet according to the above Examples and Comparative Examples, the wavelength is not converted by the quantum dots with respect to the peak intensity of blue light incident on one surface of the optical wavelength conversion sheet, and the light is emitted from the other surface of the optical wavelength conversion sheet. The emission ratio of blue light, which is the ratio of the peak intensity of blue light, was measured.

Specifically, we first prepared a Kindle Fire (registered trademark) HDX7 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. Then, in a state where the light wavelength conversion sheet is not incorporated in this backlight device, the blue light emitting diode of the backlight device is turned on, and the blue light emitted from the light emitting surface (surface of the second prism sheet) of the backlight device is emitted. Measurement angle 1 using a spectral radiance meter (product name "CS2000", manufactured by Konica Minolta) at a position 400 mm away from the light emitting surface (surface) of the backlight device in the thickness direction of the backlight device. The measurement was performed under the condition of °, and the peak intensity of blue light having a wavelength of 450 nm incident on one surface of the light wavelength conversion sheet was determined from the measured brightness distribution.

Next, an optical wavelength conversion sheet was incorporated into this backlight device. Specifically, in Examples 1 to 17, 20, 21 and Comparative Examples 1 to 9, 13 to 15, the light guide plate is arranged so that the blue light emitting diode side is the light entrance surface, and the light emission surface of the light guide plate is arranged. The light wavelength conversion sheet, the first prism sheet, and the second prism sheet according to Examples 1 to 17, 20, 21 and Comparative Examples 1 to 9, 14 to 16 are arranged in this order on the backlight device. Got The second prism sheet was arranged so that the arrangement direction of the unit prisms was orthogonal to the arrangement direction of the unit prisms of the first prism sheet.

In Examples 18 and 19 and Comparative Examples 10 to 12, the light guide plate is arranged so that the blue light emitting diode side is the light entrance surface, and the prism surface of the prism sheet is the light emission side on the light emission surface of the light guide plate. The light wavelength conversion sheet and the second prism sheet according to Examples 18 and 19 and Comparative Examples 10 to 12 were arranged in this order to obtain a backlight device. The second prism sheet was arranged so that the arrangement direction of the unit prisms was orthogonal to the arrangement direction of the unit prisms of the prism sheets in the optical wavelength conversion sheets according to Examples 18 and 19 and Comparative Examples 10 to 12. In this way, a backlight device incorporating the optical wavelength conversion sheets according to Examples 18 and 19 and Comparative Examples 10 to 12 was obtained.

Then, the blue light emitting diode of the backlight device incorporating the light wavelength conversion sheet was turned on, and blue light was irradiated to one surface of the light wavelength conversion sheet. In this state, the brightness of the light emitted from the light emitting surface of the backlight device (the surface of the second prism sheet) via the other surface of the light wavelength conversion sheet is determined by the light emission of the backlight device in the thickness direction of the backlight device. Measured at a position 400 mm away from the surface (surface) using a spectral radiance meter (product name "CS2000", manufactured by Konica Minolta) under the condition of a measurement angle of 1 °, and light wavelength conversion from the measured brightness distribution. The peak intensity of blue light with a wavelength of 450 nm emitted from the other surface of the sheet was determined.

Then, the light emission ratio of the incident light was obtained from these peak intensities obtained. Regarding the light emission ratio of the incident light, the light emission ratio of the incident light is A, the peak intensity of blue light having a wavelength of 450 nm incident on one surface of the light wavelength conversion sheet is B, and the light is emitted from the other surface of the light wavelength conversion sheet. The peak intensity of blue light having a wavelength of 450 nm was defined as C, and it was calculated by the following formula. The light emission ratio of the incident light was taken as the average value of the values obtained by measuring three times.
A = C / B x 100

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

<Measurement of brightness maintenance rate after heat resistance test>
In the light wavelength conversion sheets according to the above Examples and Comparative Examples, a heat resistance test was performed in which the light wavelength conversion sheet was left in an environment of 80 ° C. for 500 hours, and a heat resistance test for the brightness of the light wavelength conversion sheet before the heat resistance test was performed. Later, the maintenance rate of brightness was investigated. Specifically, first, a Kindle Fire (registered trademark) HDX7 backlight device was prepared, and the light wavelength conversion sheet before the heat resistance test was incorporated into this backlight device in the same manner as in the above-mentioned measurement of the light emission ratio.

Then, the blue light emitting diode of the backlight device incorporating the light wavelength conversion sheet is turned on, 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 brightness of the light emitted from the light emitting surface (the surface of the second prism sheet) is measured at a position 400 mm away from the light emitting surface (surface) of the backlight device in the thickness direction of the backlight device. Measurement was performed using "CS2000" (manufactured by Konica Minolta) under the condition of a measurement angle of 1 °.

Next, the light wavelength conversion sheet before the heat resistance test was removed from the backlight device, and the light wavelength conversion sheet was subjected to a heat resistance test in which the light wavelength conversion sheet was left in an environment of 80 ° C. for 500 hours. Then, the light wavelength conversion sheet after the heat resistance test was incorporated into the backlight device in the same manner as described above. In this state, in the same manner as described above, one surface of the light wavelength conversion sheet is irradiated with blue light, and the light emitting surface of the backlight device (the surface of the second prism sheet) passes through the other surface of the light wavelength conversion sheet. ), A spectral radiance meter (product name "CS2000", manufactured by Konica Minolta) is used at a position 400 mm away from the light emitting surface (surface) of the backlight device in the thickness direction of the backlight device. The measurement was performed under the condition of a measurement angle of 1 °.

From these measured brightnesss, the retention rate of the brightness after the heat resistance test with respect to the brightness before the heat resistance test was determined. The brightness retention rate is such that the brightness maintenance rate is D, the brightness of the light emitted from the light emitting surface of the backlight device before the heat resistance test is E, and the brightness of the light emitted from the light emitting surface of the backlight device after the heat resistance test is E. Was F, and it was calculated by the following formula. The brightness maintenance rate before and after the heat resistance test was taken as the average value of the values obtained by measuring three times.
D = F / E × 100

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

Then, the blue light emitting diode of the backlight device incorporating the light wavelength conversion sheet is turned on, 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 brightness of the light emitted from the light emitting surface (the surface of the second prism sheet) is measured at a position 400 mm away from the light emitting surface (surface) of the backlight device in the thickness direction of the backlight device. Measurement was performed using "CS2000" (manufactured by Konica Minolta) under the condition of a measurement angle of 1 °.

Next, the light wavelength conversion sheet before the moisture resistance test was removed from the backlight device, and the light wavelength conversion sheet was subjected to a moisture resistance test in which the light wavelength conversion sheet was left in an environment of 80 ° C. for 500 hours. Then, the light wavelength conversion sheet after the moisture resistance test was incorporated into the backlight device in the same manner as described above. In this state, in the same manner as described above, one surface of the light wavelength conversion sheet is irradiated with blue light, and the light emitting surface of the backlight device (the surface of the second prism sheet) passes through the other surface of the light wavelength conversion sheet. ), A spectral radiance meter (product name "CS2000", manufactured by Konica Minolta) is used at a position 400 mm away from the light emitting surface (surface) of the backlight device in the thickness direction of the backlight device. Then, the measurement was performed under the condition of a measurement angle of 1 °.

From these measured brightnesses, the maintenance rate of the brightness after the moisture resistance test was determined with respect to the brightness before the moisture resistance test. The brightness retention rate is defined as G, the brightness HE of the light emitted from the light emitting surface of the backlight device before the moisture resistance test, and the brightness of the light emitted from the light emitting surface of the backlight device after the moisture resistance test. Let it be I, and it was calculated by the following formula. The brightness maintenance rate before and after the moisture resistance test was taken as the average value of the values obtained by measuring three times.
G = I / H × 100

<Measurement of brightness maintenance rate after light resistance test>
In the light wavelength conversion sheets according to the above Examples and Comparative Examples, a light resistance test was performed in which the light wavelength conversion sheet was irradiated with light from a carbon arc lamp for 200 hours in an environment of 42 ° C. and a relative humidity of 50%, and the light wavelength conversion was performed. The maintenance rate of the brightness after the light resistance test with respect to the brightness before the light resistance test on the sheet was investigated. Specifically, first, a Kindle Fire (registered trademark) HDX7 backlight device was prepared, and the light wavelength conversion sheet before the light resistance test was incorporated into this backlight device in the same manner as in the measurement of the light emission ratio.

Then, the blue light emitting diode of the backlight device incorporating the light wavelength conversion sheet is turned on, 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 brightness of the light emitted from the light emitting surface (the surface of the second prism sheet) is measured at a position 400 mm away from the light emitting surface (surface) of the backlight device in the thickness direction of the backlight device. Measurement was performed using "CS2000" (manufactured by Konica Minolta) under the condition of a measurement angle of 1 °.

Next, the light wavelength conversion sheet before the light resistance test is removed from the backlight device, and the light wavelength conversion sheet is irradiated with light from a carbon arc lamp for 200 hours in an environment of 42 ° C. and a relative humidity of 50%. Was done. Then, the light wavelength conversion sheet after the light resistance test was incorporated into the backlight device in the same manner as described above. In this state, in the same manner as described above, one surface of the light wavelength conversion sheet is irradiated with blue light, and the light emitting surface of the backlight device (the surface of the second prism sheet) passes through the other surface of the light wavelength conversion sheet. ), A spectral radiance meter (product name "CS2000", manufactured by Konica Minolta) is used at a position 400 mm away from the light emitting surface (surface) of the backlight device in the thickness direction of the backlight device. Then, the measurement was performed under the condition of a measurement angle of 1 °.

From these measured brightnesses, the maintenance rate of the brightness after the light resistance test with respect to the brightness before the light resistance test was determined. The brightness retention rate is such that the brightness retention rate is J, the brightness of the light emitted from the light emitting surface of the backlight device before the light resistance test is K, and the brightness of the light emitted from the light emitting surface of the backlight device after the light resistance test is K. Was L, and it was calculated by the following formula. The brightness maintenance rate before and after the light resistance test was taken as the average value of the values obtained by measuring three times.
J = L / K × 100

<Evaluation of point-shaped brightness defects>
Using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the heat resistance test according to the above-mentioned Example and the above-mentioned Comparative Example, whether or not there is a punctate brightness defect on the light emitting surface at the time of light emission in the backlight device. It was visually observed and evaluated. Further, using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the moisture resistance test and the above-mentioned backlight device incorporating the light wavelength conversion sheet after the light resistance test according to the above-mentioned Examples and the above-mentioned Comparative Examples. Similarly, it was visually observed and evaluated whether or not there was a point-like brightness defect on the light emitting surface at the time of light emission in the backlight device.
◯: No point-shaped luminance defect was confirmed.
Δ: Several point-shaped luminance defects were confirmed.
X: Many point-shaped luminance defects were confirmed.

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

The results are shown in Tables 1 to 4 below.

The results will be described below. As can be seen from Tables 1 to 4, since the light wavelength conversion sheets according to Examples 1 to 19 contain phenolic compounds and amine compounds, Comparative Example 1 containing no phenolic compounds or amine compounds. Compared with the light wavelength conversion sheet according to ~ 12, the brightness retention rate after the heat resistance test, the moist heat resistance test, and the light resistance test was higher. Further, since the optical wavelength conversion sheets according to Examples 20 and 21 contain phenolic compounds and amine compounds, the optical wavelength conversion sheets according to Comparative Examples 13 to 15 which do not contain phenolic compounds or amine compounds. The brightness retention rate after the heat resistance test, the moist heat resistance test, and the light resistance test was higher than that of the above. This is because the light wavelength conversion compositions 1 to 12 and the cured product thereof have high heat resistance, heat resistance, and light resistance, and the light wavelength conversion composition and the light wavelength conversion layer are phenolic compounds or amines. The inclusion of system compounds means that the deterioration of quantum dots can be suppressed. Bechenic acid amide and 4-phenylbenzoylhydrazine in the light wavelength conversion compositions 14, 15 used in Comparative Examples 2, 3, 5, 6, 8, 9, 11, 12, 14, and 15 are used as antioxidants. However, it is not a phenolic compound or an amine compound. From this, it can be understood that even a compound having a function as an antioxidant cannot always suppress the deterioration of quantum dots. Further, in the light wavelength conversion sheets according to Examples 1 to 21, the light emission ratio of the incident light was 10% or more. This means that in the optical wavelength conversion sheet according to Examples 1 to 21, it is difficult for the phenolic compound or the amine compound to absorb the incident light (blue light).

Since no barrier member was used in the optical wavelength conversion sheets according to Examples 1 to 19 and Comparative Examples 1 to 12, no punctate luminance defect was confirmed. Further, in the light wavelength conversion sheets according to Examples 20 and 21, a barrier member was used, but since it contained a phenolic compound or an amine compound, no punctate luminance defect was confirmed. On the other hand, in the light wavelength conversion sheets according to Comparative Examples 13 to 15 in which the phenol-based compound or the amine-based compound was not used, a punctate luminance defect was confirmed. This means that the deterioration of quantum dots can be suppressed by using a phenol-based compound or an amine-based compound.

In the light wavelength conversion sheets according to Examples 1 to 21, since a phenol-based compound or an amine-based compound was used, deterioration of the peripheral portion was suppressed. This means that when a phenol-based compound or an amine-based compound is used, it has an effect of suppressing deterioration of quantum dots. On the other hand, even in the optical wavelength conversion sheet according to Comparative Examples 1 to 12 in which the phenolic compound or the amine compound was not used, the result of deterioration of the peripheral portion was 0 mm, but this was because the optical wavelength conversion layer was used. This is because the quantum dots were deteriorated as a whole in the heat resistance test, the moist heat resistance test, and the light resistance test because they were exposed, and there was almost no difference in brightness between the peripheral portion and the central portion. Further, in the light wavelength conversion sheets according to Comparative Examples 13 to 15, the deterioration of the central portion was relatively suppressed by the barrier member, but the deterioration of the peripheral portion was not suppressed.

The total haze value of the light wavelength conversion sheet according to the first embodiment is 98.9%, the internal haze value is 96.7%, and the external haze value is 2.2%. The haze value was 99.3%, the internal haze value was 99.3%, and the external haze value was 0%. Since the external haze value is smaller than the internal haze value in both light wavelength conversion sheets, the brightness is high regardless of before and after the durability test. Comparing the light wavelength conversion sheets according to No. 2, the light wavelength conversion sheet according to Example 2 had higher brightness regardless of before and after the moisture resistance test. This is because the light wavelength conversion sheet according to Example 2 contains alumina particles as light scattering particles, so that the internal haze value of the light wavelength conversion sheet according to Example 2 is that of the wavelength conversion sheet according to Example 1. This is because the haze value is larger than the internal haze value, which makes the external haze value smaller. Therefore, it was confirmed that the external haze value can be made smaller by including the light scattering particles in the light wavelength conversion sheet to further increase the internal haze value, and thereby the light wavelength conversion efficiency can be further improved. .. The total haze value, the internal haze value, and the haze value in the optical wavelength conversion sheet were measured as follows. First, using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Laboratory), the total haze value of the optical wavelength conversion sheet was measured according to JIS K7136. After that, a triacetyl cellulose base material having a thickness of 60 μm (product name “Panaclean PD-S1”, manufactured by Panac Co., Ltd.) is interposed on both sides of the optical wavelength conversion sheet via a transparent optical adhesive layer (product name “Panaclean PD-S1”, manufactured by Panac Co., Ltd.) having a thickness of 25 μm (product name “Panaclean PD-S1”). TD60UL ", manufactured by Fujifilm Co., Ltd.) was pasted. As a result, the uneven shape of the surface of the light wavelength conversion sheet was crushed, and the surface of the light wavelength conversion sheet became flat. In this state, the haze value was measured according to JIS K7136 using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Laboratory) to obtain the internal haze value. Then, the external haze value was obtained by subtracting the internal haze value from the total haze value. The transparent optical adhesive layer and the triacetyl cellulose base material may also affect the internal haze value and the external haze value of the optical wavelength conversion sheet, but when the internal scattering of the optical wavelength conversion sheet is extremely large, these may affect the internal haze value and the external haze value. The effect on the internal haze value and the external haze value is extremely small and can be ignored. Further, when the internal scattering of the light wavelength conversion sheet is extremely large, the internal haze value may be the same as the total haze value, so that the external haze value may be 0%.

Further, in the optical wavelength conversion sheets according to Examples 15 and 16, a scratch test was performed on the overcoat layer, and the normal force and the horizontal force at that time were measured. As a result, the optical wavelength conversion sheet according to Example 15 was found. The normal force was 21 μN and the horizontal force was -11 μN, and the optical wavelength conversion sheet according to Example 15 had a normal force of 11 μN and a horizontal force of -6 μN. These overcoat layers became dense films and had an ability to prevent the light wavelength conversion layer from exposure to the atmosphere. However, in terms of the ability to prevent the light wavelength conversion layer from exposure to the atmosphere, the light wavelength conversion sheet according to Example 15 It can be said that the overcoat layer is higher than the overcoat layer of the optical wavelength conversion sheet according to Example 16. The scratch test is performed using a nanoindentation device (product name "TI950 TriboIndenter", manufactured by HYSITRON) from the cross section of the overcoat layer to the inside of the overcoat layer (Cube Corner: Ti037_110410 (12)). ) Is pushed in by 50 nm, the depth is kept constant, and the indenter is moved horizontally at a moving speed of 4 μm / min for 30 seconds, and the normal force (load) and horizontal force at that time are measured and measured. The average value of the normal force and the horizontal force was obtained, and the average value of the five average values of the normal force (five times average value) obtained by repeating this scratch test five times was used as the normal force, and the five horizontal forces were used. The average value of the average values (5 times average value) was used as the normal force.

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

10, 20, 30, 40, 50, 60 ... Light wavelength conversion sheet 11, 170 ... Light wavelength conversion layer 16 ... Binder resin 17 ... Quantum dots 18 ... Light scattering particles 19 ... Coating 70 ... Image display device 80, 130 , 140, 160 ... Backlight device 120 ... Display panel 154 ... Light wavelength conversion member

Claims (6)

An optical wavelength conversion sheet including at least an optical wavelength conversion layer.
The light wavelength conversion layer contains a binder resin, quantum dots, and one or more compounds selected from the group consisting of phenolic compounds and amine compounds.
When one surface of the optical wavelength conversion sheet is irradiated with light whose wavelength can be converted by the quantum dots, the wavelength is not converted by the quantum dots with respect to the peak intensity of the light incident on one surface of the optical wavelength conversion sheet. In addition, the ratio of the peak intensity of the light emitted from the other surface, which is the surface opposite to the one surface in the light wavelength conversion sheet, is 10% or more.
40 ° C. in the optical wavelength conversion sheet, the water vapor transmission rate is 1g ^/ (m 2 · 24h) or 42g ^/ (m 2 · 24h) or less at 90% relative humidity, the optical wavelength conversion sheet. Before and after the light resistance test in which the light wavelength conversion sheet is irradiated with light for 200 hours in an environment of 42 ° C. and 50% relative humidity, the wavelength can be converted by the quantum dots on the one surface of the light wavelength conversion sheet, respectively. When the brightness of the light emitted from the other surface of the light wavelength conversion sheet is measured by irradiating a predetermined amount of light, the brightness of the brightness after the light resistance test is compared with the brightness before the light resistance test. The optical wavelength conversion sheet according to claim 1, wherein the maintenance rate is 80% or more. The light wavelength conversion sheet according to claim 1 or 2, further comprising an optical member arranged on at least one surface side of the light wavelength conversion layer and integrated with the light wavelength conversion layer. 23 ° C. in the optical wavelength conversion sheet is the oxygen permeability at a relative humidity of 90% ^{0.1cm 3 / (m 2 · 24h} · atm) or more ^{61cm 3 / (m 2 · 24h} · atm) or less, claims The optical wavelength conversion sheet according to any one of 1 to 3. Light source and
A backlight device comprising the light wavelength conversion sheet according to any one of claims 1 to 4, which receives light from the light source. The backlight device according to claim 5 and
An image display device including a display panel arranged on the light emitting side of the backlight device.

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