JP6690257B2 - Light wavelength conversion sheet, backlight device, and image display device - Google Patents

Description

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

  A transmissive image display device such as a liquid crystal display device is generally provided with a backlight device which is arranged on the back side of a transmissive image display panel such as a liquid crystal display panel and illuminates the transmissive image display panel. As a backlight device, an edge light type or a direct type backlight device is known.

  Currently, in order to improve color reproducibility, it is considered to arrange a light wavelength conversion sheet having a light wavelength conversion layer containing quantum dots and a binder resin on a light guide plate or a light source in a backlight device (for example, patents Reference 1). Quantum dots can absorb light and emit light of different wavelengths. The wavelength of light emitted by the quantum dots mainly depends on the particle size of the quantum dots. Therefore, in the backlight device in which the light wavelength conversion sheet is incorporated, 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 may absorb blue light and emit green light and red light. Since a backlight device incorporating such a light wavelength conversion sheet has excellent color purity, a display device using this backlight device has excellent color reproducibility.

JP, 2015-111518, A

  In the light wavelength conversion sheet, the quantum dots may be deteriorated by moisture or oxygen, and the luminous efficiency may be reduced. Therefore, at present, both sides of the light wavelength conversion layer are used to suppress the transmission of moisture and oxygen. A barrier film is provided. Since the barrier film is provided so as to sandwich the light wavelength conversion layer, the light wavelength conversion sheet has a structure in which the barrier film, the light wavelength conversion layer, and the barrier film are laminated in this order.

  However, when the light wavelength conversion sheet is used, the quantum dots may deteriorate over time, and therefore, further suppression of further deterioration over time of the quantum dots is currently desired. Here, the barrier film is in close contact with both sides of the light wavelength conversion layer, but if the adhesion between the light wavelength conversion layer and the barrier film decreases, peeling occurs at the interface between the light wavelength conversion layer and the barrier film, which Since the quantum dots may be deteriorated by water and oxygen, it is desired to suppress the further deterioration of the quantum dots with time while ensuring the adhesiveness between the light wavelength conversion layer and the barrier film.

  The present invention has been made to solve the above problems. That is, an object of the present invention is to provide a light wavelength conversion sheet, a backlight device and an image display device capable of suppressing the deterioration of quantum dots over time while ensuring the adhesiveness between the light wavelength conversion layer and the barrier film.

  When the volatile organic compound as the solvent remains in the light wavelength conversion layer, curing is apt to be insufficient, and the volatile organic compound remains from the viewpoint that the film hardness of the light wavelength conversion layer and the adhesion with the barrier film decrease. It is a common technical knowledge to prepare a light wavelength conversion layer so that the light wavelength conversion layer does not exist. Surprisingly, the present inventors intentionally leave a proper amount of a volatile organic compound in the light wavelength conversion layer, thereby The inventors have found that the deterioration of the quantum dots over time can be suppressed while ensuring the adhesion between the conversion layer and the barrier film, and have completed the present invention.

According to an aspect of the present invention, there is provided a light wavelength conversion sheet, the light wavelength conversion layer including a binder resin and quantum dots dispersed in the binder resin, and provided on both surface sides of the light wavelength conversion layer. And a barrier film that suppresses the permeation of moisture and oxygen, and the residual amount of at least one volatile organic compound in the light wavelength conversion sheet per unit area is 10 mg / m ² or more and 500 mg / m ² or less. A light wavelength conversion sheet is provided.

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

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

  According to the light wavelength conversion sheet of one aspect of the present invention and the backlight device and the image display device of other aspects, while suppressing the deterioration with time of the quantum dots while ensuring the adhesiveness between the light wavelength conversion layer and the barrier film. You can do it.

It is a schematic block diagram of the light wavelength conversion sheet which concerns on embodiment. It is a schematic diagram which shows the effect | action of the light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the other light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the other light wavelength conversion sheet which concerns on embodiment. It is a schematic manufacturing process drawing of the light wavelength conversion sheet according to the embodiment. It is a schematic manufacturing process drawing of the light wavelength conversion sheet according to the embodiment. 1 is a schematic configuration diagram of an image display device including a backlight device according to an embodiment. FIG. 8 is a perspective view of the lens sheet shown in FIG. 7. FIG. 9 is a cross-sectional view taken along line I-I of the lens sheet of FIG. 8. It is a schematic block diagram of the other backlight apparatus which concerns on embodiment.

  Hereinafter, a light wavelength conversion sheet, a backlight device, and a display device according to embodiments 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, "film" is used to include a member that is also called a sheet, and "sheet" is used to include a member that can also be called a film. FIG. 1 is a schematic configuration diagram of a light wavelength conversion sheet according to the present embodiment, FIG. 2 is a schematic diagram showing an operation of the light wavelength conversion sheet according to the embodiment, and FIGS. 3 and 4 are related to the present embodiment. It is a schematic block diagram of another light wavelength conversion sheet.

<<< 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 another part of the incident light and the wavelength-converted light. is there. The light wavelength conversion sheet 10 includes a light wavelength conversion layer 11, barrier films 12 and 13 provided on both sides of the light wavelength conversion layer 11 and suppressing transmission of moisture and oxygen, and light wavelengths in the barrier films 12 and 13. The light diffusion layers 14 and 15 are provided on the surface opposite to the surface on the conversion layer 11 side. In the light wavelength conversion sheet 10, the surfaces of the light diffusion layers 14 and 15 form the surface of the light wavelength conversion sheet 10.

  The light wavelength conversion sheet 10 has a structure of light diffusion layer 14 / barrier film 12 / light wavelength conversion layer 11 / barrier film 13 / light diffusion layer 15, but the light wavelength conversion sheet is a light wavelength conversion layer and a barrier film. The structure of the light wavelength conversion sheet is not particularly limited as long as it has For example, the light wavelength conversion sheet may have a structure of light diffusion layer / barrier film / light wavelength conversion layer / barrier film, or barrier film / light wavelength conversion layer / barrier film.

In the light wavelength conversion sheet 10, the residual amount of the volatile organic compound contained in the light wavelength conversion sheet 10 per unit area is 10 mg / m ² or more and 500 mg / m ² or less. The "volatile organic compound" in the present specification means an organic compound having a property of easily evaporating at room temperature. Examples of the volatile organic solvent include organic compounds having a boiling point of 75 ° C or higher. Among the organic compounds having a boiling point of 75 ° C or higher, those having a boiling point of 170 ° C or lower are preferable. The term "residual amount of volatile organic compound" refers to the total amount of volatile organic compounds remaining when two or more volatile organic compounds remain in the light wavelength conversion sheet. Shall mean.

The volatile organic compound is mainly the solvent used when forming the light wavelength conversion sheet, for example, the solvent contained in the light wavelength conversion layer composition. Therefore, the volatile organic compound remaining in the light wavelength conversion sheet is the residual solvent remaining in the light wavelength conversion sheet. If the amount of the volatile organic compound contained in the light wavelength conversion sheet is less than 10 mg / m ² , the deterioration of the quantum dots over time may not be suppressed, and the amount of the volatile organic compound contained in the light wavelength conversion sheet may be too small. If it exceeds 500 g / m ³ , the curing tends to be insufficient, and the film hardness of the light wavelength conversion layer and the peeling strength from the barrier film may decrease, so that the adhesion between the light wavelength conversion layer and the barrier film may not be secured. The lower limit of the amount of the volatile organic compound contained in the light wavelength conversion sheet 10 is preferably 20 mg / m ² or more, and more preferably 50 mg / m ² or more. The upper limit of the amount of the volatile organic compound contained in the light wavelength conversion sheet 10 is preferably 300 g / m ² or less, and more preferably 100 g / m ³ or less.

The residual amount of the volatile organic compound contained in the light wavelength conversion sheet 10 is measured by the following residual amount measuring method.
(Residual amount measurement method)
First, a light wavelength conversion sheet equivalent to 1 cm × 2 cm is put in a 20 ml vial having an internal capacity and sealed. Here, when the barrier film is present on both sides of the light wavelength conversion layer, the volatile organic compound remaining in the light wavelength conversion layer is difficult to volatilize, so one of the barrier films is peeled from the light wavelength conversion sheet. , The peeled barrier film and the remaining portion of the light wavelength conversion sheet in which the light wavelength conversion layer is exposed are divided into the light wavelength conversion sheet (the peeled barrier film and the remaining portion of the light wavelength conversion sheet). It shall be placed in the vial bottle. Then, after heating the sealed vial bottle containing the light wavelength conversion sheet and at 160 ° C. for 15 minutes, a certain amount of gas in the vial bottle was extracted and subjected to gas chromatography (Agilent Technology Co., Ltd. 6890N GC). The volatile organic compound contained in the loaded gas is quantified, and the residual amount (mg / m ² ) of the volatile organic compound contained in 1 m ^{2 of the} light wavelength conversion sheet is measured. calculate.

The light wavelength conversion sheet 10 having a residual amount of the volatile organic compound of 10 mg / m ² or more and 500 mg / m ² or less becomes the light wavelength conversion layer 11 by curing, and the volatile organic compound as a solvent in the composition for the light wavelength conversion layer. It can be obtained by adjusting the amount of the compound and / or the drying temperature of the composition for a light wavelength conversion layer.

  The volatile organic compound may be either a polar volatile organic compound or a non-polar volatile organic compound, but from the viewpoint of further suppressing deterioration of the quantum dots due to moisture or oxygen in the air, a non-polar volatile organic compound It is preferably a volatile organic compound. The volatile organic compound may also be a mixture of polar volatile organic compounds and non-polar volatile organic compounds. In the present specification, the “polar volatile organic compound” means a volatile organic compound having a relative dielectric constant of 6 or more at 20 ° C., and the “nonpolar volatile organic compound” is at 20 ° C. It means a volatile organic compound having a relative dielectric constant of less than 6.

  Examples of polar volatile organic compounds include alcohols such as methanol, ethanol, propanol and isopropyl alcohol; ketones such as methyl ethyl ketone and methyl isobutyl ketone. Among these, ethanol is preferable from the viewpoint of improving the dispersibility of quantum dots.

  Examples of the non-polar solvent include toluene and cyclohexane. Among these, toluene is preferable from the viewpoint of improving the dispersibility of the quantum dots.

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

  The average thickness of the light wavelength conversion sheet 10 is calculated using, for example, an image of a cross section taken at random 20 locations with a scanning electron microscope (SEM), a transmission electron microscope (TEM), or a scanning transmission electron microscope (STEM). it can. Among these, it is preferable to use SEM, considering that the film thickness of the light wavelength conversion sheet 10 is on the order of μm. In the case of SEM, the acceleration voltage is preferably 30 kV and the magnification is 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.

<< Light wavelength conversion layer >>
In the light wavelength conversion layer 11, for the same reason as the reason for defining the remaining amount of the volatile organic compound contained in the light wavelength conversion sheet 10, the volatile organic compound contained in the light wavelength conversion layer 11 per unit area is The residual amount is preferably 10 mg / m ² or more and 500 mg / m ² or less. The lower limit of the amount of the volatile organic compound contained in the light wavelength conversion layer 11 is more preferably 20 mg / m ² or more, further preferably 50 mg / m ² or more. The upper limit of the amount of the volatile organic compound contained in the light wavelength conversion layer 11 is more preferably 300 g / m ² or less, and further preferably 100 g / m ³ or less.

  The residual amount of the volatile organic compound contained in the light wavelength conversion layer 11 is measured by the above-mentioned residual amount measuring method. When measuring the residual amount of the volatile organic compound contained in the light wavelength conversion layer 11, Instead of putting the light wavelength conversion sheet in the vial bottle, the barrier film and the light diffusion layer are peeled off from the light wavelength conversion sheet to leave only the light wavelength conversion layer, and only the light wavelength conversion layer is put in the vial bottle.

  The light wavelength conversion layer 11 includes a binder resin 16 and quantum dots 17 dispersed in the binder resin 16 to convert the wavelength of incident light. Moreover, it is preferable that the light wavelength conversion layer 11 further includes light scattering particles 18.

  The light wavelength conversion layer 11 has a substantially uniform film thickness. The average film thickness of the light wavelength conversion layer 11 is preferably 10 μm or more and 150 μm or less. When the film thickness of the light wavelength conversion layer 11 is in this range, it is suitable for reducing the weight and thinning the backlight device. The film thickness of the light wavelength conversion layer 11 can be calculated from the image of the cross section of the light wavelength conversion sheet, which is randomly photographed at 20 locations using a scanning electron microscope (SEM). The lower limit of the average film thickness of the light wavelength conversion layer 11 is more preferably 30 μm or more.

<Binder resin>
The binder resin 16 is not particularly limited, but may be a cured product (polymerized product or crosslinked product) of a curable binder resin precursor. Examples of the curable binder resin precursor include photopolymerizable compounds and / or thermosetting resins such as epoxy resins. The photopolymerizable compound has at least one photopolymerizable functional group. In the present specification, the “photopolymerizable functional group” is a functional group capable of undergoing a polymerization reaction by irradiation with light. Examples of the photopolymerizable functional group include ethylenic double bonds such as (meth) acryloyl group, vinyl group and allyl group. The “(meth) acryloyl group” is meant to include both “acryloyl group” and “methacryloyl group”. In addition, examples of the light irradiated when the photopolymerizable compound is polymerized include visible light, and ionizing radiation such as ultraviolet rays, X-rays, electron rays, α rays, β rays, and γ rays.

  Examples of the photopolymerizable compound include a photopolymerizable monomer, a photopolymerizable oligomer, and a photopolymerizable prepolymer, which can be appropriately adjusted and used. The photopolymerizable compound is preferably a combination of a photopolymerizable monomer and a photopolymerizable oligomer or photopolymerizable prepolymer.

  The photopolymerizable monomer has a weight average molecular weight of 1,000 or less. Examples of the photopolymerizable monomer include monomers having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate, ethylene glycol di (meth) acrylate, and the like. Diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) Acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol Tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, glycerol (meth) (meth) acrylic acid esters such as acrylate.

  The photopolymerizable oligomer has a weight average molecular weight of more than 1,000 and 10,000 or less. As the photopolymerizable oligomer, a polyfunctional oligomer having two or more functional groups is preferable, and a polyfunctional oligomer having three (trifunctional) or more photopolymerizable functional groups is 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, isocyanurate. Examples thereof include (meth) acrylate and epoxy (meth) acrylate.

  The photopolymerizable prepolymer has a weight average molecular weight of more than 10,000, and the weight average molecular weight is preferably more than 10,000 and 80,000 or less, more preferably more than 10,000 and 40,000 or less. When the weight average molecular weight exceeds 80,000, the viscosity is high, and thus the coating suitability is deteriorated, and the appearance of the obtained light wavelength conversion layer may be deteriorated. Examples of the polyfunctional prepolymer include urethane (meth) acrylate, isocyanurate (meth) acrylate, polyester-urethane (meth) acrylate, and epoxy (meth) acrylate.

  The thermosetting resin is not particularly limited, and examples thereof include phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, aminoalkyd resin, melamine-urea cocondensation resin. Resin, silicon resin, polysiloxane resin and the like can be mentioned. The thermosetting resins may be used alone or in combination of two or more. Among these, epoxy resin and urethane resin are preferable from the viewpoint of curability and heat resistance.

  Examples of the epoxy resin include a combination of an epoxy resin (main ingredient), an acid anhydride, an amine compound, or an amino resin (curing agent), and a cationic photopolymerization initiator. The epoxy resin as the main agent is not particularly limited as long as it has an epoxy group in one molecule, and examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol S type. Epoxy resin, diphenyl ether type epoxy resin, hydroquinone type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, fluorene type epoxy resin, phenol novolac type epoxy resin, orthocresol novolac type epoxy resin, trishydroxyphenylmethane type epoxy resin, 3 Functional type epoxy resin, tetraphenylolethane type epoxy resin, dicyclopentadiene phenol type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol A nucleus-containing poly Lumpur type epoxy resins, polypropylene glycol type epoxy resins, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, glyoxal type epoxy resins, alicyclic epoxy resins, and the like heterocyclic epoxy resin.

  Examples of the urethane resin include a combination of a polyol compound (main agent) and an isocyanate compound (curing agent). In the urethane resin, the polyol compound used as the main component is not particularly limited, and examples thereof include polyester polyol, polyester polyurethane polyol, polyether polyol, polyether polyurethane polyol and the like. These polyol compounds may be used alone or in combination of two or more.

  In the urethane resin, the isocyanate-based compound used as a curing agent is not particularly limited, and examples thereof include polyisocyanate, an adduct thereof, a modified isocyanurate thereof, a modified carbodiimide thereof, a modified alohanate thereof, and a buret thereof. Examples include modified products and the like. Specific examples of the polyisocyanate include diphenylmethane diisocyanate (MDI), polyphenylmethane diisocyanate (polymeric MDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), and bis (4-isocyanate cyclohexyl) methane (H12MDI). , Isophorone diisocyanate (IPDI), 1,5-naphthalene diisocyanate (1,5-NDI), 3,3′-dimethyl-4,4′-diphenylene diisocyanate (TODI), xylene diisocyanate (XDI) and other aromatic diisocyanates Aliphatic diisocyanates such as tramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate DOO; 4,4'-methylenebis (cyclohexyl isocyanate), alicyclic diisocyanates such as isophorone diisocyanate. Specific examples of the adduct include those obtained by adding trimethylolpropane, glycol or the like to the polyisocyanate. These isocyanate compounds may be used alone or in combination of two or more.

<Quantum dot>
The quantum dots 17 are nano-sized semiconductor particles having a quantum confinement effect. The particle size and average particle size of the quantum dots 17 are, for example, 1 nm or more and 20 nm or less. When the quantum dot 17 absorbs light from the excitation source and reaches the energy excited state, the quantum dot 17 emits energy corresponding to the energy band gap of the quantum dot 17. Therefore, if the particle diameter of the quantum dots 17 or the composition of the substance is adjusted, the energy band gap can be adjusted, and energy in various wavelength bands can be obtained. In particular, the quantum dots 17 can generate strong fluorescence in a narrow wavelength band.

  Specifically, the energy band gap of the quantum dots 17 increases as the particle diameter decreases. That is, as the crystal size becomes smaller, the quantum dot emission 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 range of the spectrum in the ultraviolet region, the visible region, and the infrared region. For example, when the quantum dots are composed of CdSe / ZnS described later, blue light is emitted when the particle size of the quantum dots is 2.0 nm or more and 4.0 nm or less, and the particle size of the quantum dots is 3.0 nm. When it is 6.0 nm or less, green light is emitted, and when the particle size of the quantum dot is 4.5 nm or more and 10.0 nm or less, red light is emitted. In the above, the particle size range of the quantum dots emitting blue light and the particle size range of the quantum dots emitting green light partially overlap, and the particle size of the quantum dots emitting green light and the red light are Although the range of particle diameters of emitted quantum dots partially overlaps, even for quantum dots having the same particle diameter, the emission color may differ depending on the thickness of the quantum dot shell, so there is no contradiction. Not a thing.

  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 It is light having a wavelength range of 590 nm or more and 750 nm or less.

  As the quantum dots 17 included in the light wavelength conversion layer 11, one type of quantum dots may be used, but it is also possible to use at least two types of quantum dots having different particle diameters or materials. As shown in FIG. 1, the light wavelength conversion layer 11 includes, as the quantum dots 17, a first quantum dot 17A and a second quantum dot 17B having a particle diameter larger than that of the first quantum dot 17A. .

  As shown in FIG. 2, when light is incident from the light incident surface 10A of the light wavelength conversion sheet 10, the light L1 incident on the quantum dots 17 is converted into light L2 having a wavelength different from that of the light L1. The light exits from the light exit surface 10B, which is the surface opposite to the light entrance surface 10A. On the other hand, even when light is incident from the light incident surface 10A, the light L1 passing between the quantum dots 17 is emitted from the light emitting surface 10B without wavelength conversion.

  As described above, since the light emitted from the light wavelength conversion sheet 10 includes some light whose wavelength is not converted, a light source that emits blue light is used as a light source, and blue light is converted into green light as the first quantum dots 17A. When a quantum dot is used and a quantum dot that converts blue light into red light is used as the second quantum dot 17B, light in which blue light, green light, and red light are mixed is emitted from the light wavelength conversion sheet 10. Can be made.

  The quantum dots 17 can generate strong fluorescence in a desired narrow wavelength range. Therefore, the backlight device using the light wavelength conversion sheet 10 can illuminate the display panel with light of the three primary colors having excellent color purity. In this case, the display panel has excellent color reproducibility.

  The quantum dots 17 may have a core-shell structure having a core mainly made of a semiconductor compound of about 2 nm or more and 10 nm or less and a shell made of a semiconductor compound different from the core. The shell has a function as a protective layer that protects the core.

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

  The shell uses a semiconductor compound having a bandgap higher than that of the semiconductor compound forming the core so that the excitons are confined in the core, whereby the luminous efficiency of the quantum dots can be increased. Examples of the core-shell structure (core / shell) having such a band gap magnitude relation include CdSe / ZnS, CdSe / ZnSe, CdSe / CdS, CdTe / CdS, InP / ZnS, Gap / ZnS, Si / ZnS, Examples include InN / GaN, InP / CdSSe, InP / ZnSeTe, InGaP / ZnSe, InGaP / ZnS, Si / AlP, InP / ZnSTe, InGaP / ZnSTe, InGaP / ZnSSe, and the like.

  The quantum dots 17 may have an organic polymer called a ligand on the outside of the shell. The organic polymer has a function of enhancing the compatibility between the quantum dots and the binder resin, and is appropriately selected depending on the kind of the binder resin.

  The shape of the quantum dots 17 is not particularly limited, and may be, for example, a spherical shape, a rod shape, a disk shape, or another shape. The particle size of the quantum dots 17 can be a true spherical value having the same volume when the quantum dots 17 are not spherical.

  Regarding the information such as the particle diameter, average particle diameter, shape, and dispersion state of the quantum dots 17, the diameter of 20 quantum dots measured by observing the cross section of the light wavelength conversion layer with a transmission electron microscope or a scanning transmission electron microscope. Can be obtained from In addition, since the emission color of the quantum dot changes depending on the particle diameter, it is possible to determine the particle diameter of the quantum dot by confirming the emission color of the quantum dot. For example, when the quantum dots are composed of CdSe / Zn, if green emission can be confirmed from the quantum dots, it can be considered that the particle size of the quantum dots is 3.0 nm or more and 6.0 nm or less. The crystal structure and crystallite size of the quantum dots can be known by X-ray crystal diffraction (XRD). Furthermore, it is also possible to obtain information regarding the particle size of the quantum dots and the like from the ultraviolet-visible (UV-Vis) absorption spectrum.

  The content of the quantum dots 17 in the light wavelength conversion layer 11 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. When the content of the quantum dots is less than 0.01% by mass, sufficient emission intensity may not be obtained, and when the content of the quantum dots exceeds 2% by mass, sufficient transmitted light of excitation light is obtained. The strength may not be obtained. The mass% of the quantum dots in the light wavelength conversion layer that is a cured product and the mass% of light-scattering particles described later can be roughly calculated by the following method. First, at least a part of the light wavelength conversion layer is sampled from the light wavelength conversion sheet, and its mass is measured. Then, the host matrix contained in the sampled portion is dissolved or burned in a solvent to be incinerated to remove the components of the host matrix. When the components of the host matrix are removed, the quantum dots and the light-scattering particles are not removed, and the components of the quantum dots and the light-scattering particles have large particle diameters. Separate the components of the scattering particles. Next, the mass of the separated quantum dot component and the light scattering particle component are measured. Then, the ratio of the mass of the quantum dots contained in at least a part of the sampled light wavelength conversion layer is calculated based on the mass of at least a part of the sampled light wavelength conversion layer and the mass of the quantum dots. Further, the mass ratio of the light scattering particles contained in at least a part of the sampled light wavelength conversion layer is calculated based on the mass of the sampled light wavelength conversion layer and the mass of the light scattering particles.

<Light scattering particles>
The light-scattering particles 18 are particles having a function of changing the light that has entered the light wavelength conversion sheet 10 by scattering the light.

  The content of the light-scattering particles 18 in the light wavelength conversion layer 11 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. When the content of the light scattering particles is less than 1% by mass, the light scattering effect may not be sufficiently obtained, and when the content of the light scattering particles exceeds 50% by mass, Mie scattering occurs. Since it becomes difficult, the light-scattering effect may not be sufficiently obtained, and further, the workability may be deteriorated because there are too many light-scattering particles.

  The average particle diameter of the light-scattering particles 18 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. When 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 in order to obtain sufficient light scattering properties, It is necessary to increase the addition amount. On the other hand, when the average particle diameter 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 the number of scattering points decreases and a sufficient light-scattering effect is obtained. Can't get

  The absolute value of the refractive index difference 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. Either of 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, Becke method, minimum deviation method, deviation analysis, mode line method, ellipsometry method, etc. can do. The binder resin (cured product) in the light wavelength conversion layer and the refractive index of the light-scattering particles can be measured, for example, by measuring the light-scattering particle fragments or the host matrix fragments from the cured and manufactured light wavelength conversion layer. The Becke method can be used for what is taken out in some form. In addition, the refractive index difference 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 Optics Laboratories or a two-beam interference microscope manufactured by Mizojiri Optical Co. can do. When the binder resin contains the above-mentioned (meth) acrylate and a resin other than that, the refractive index of the binder resin means a cured product of all the resin components contained except the quantum dots and the light scattering particles. Means the average refractive index of.

  The shape of the light-scattering particles 18 is not particularly limited, and examples thereof include spherical shapes (true spheres, substantially true spheres, elliptical spheres, etc.), polyhedron shapes, rod shapes (cylindrical shapes, prismatic shapes, etc.), flat plate shapes, scaly shapes, indefinite shapes. Shape etc. are mentioned. The particle size of the light-scattering particles 18 can be a true spherical value having the same volume when the light-scattering particles are not spherical in shape.

  The light-scattering particles 18 are preferably chemically bonded to the binder resin 16 from the viewpoint of firmly fixing the light-scattering particles 18 in the binder resin 16. This chemical bond can be realized by using light-scattering particles whose surface is treated with a silane coupling agent.

  The silane coupling agent, depending on the type of curable binder resin precursor used, vinyl group, epoxy group, styryl group, methacryl group, acryl group, amino group, ureido group, mercapto group, sulfide group and isocyanate group It is possible to use those having one or more reactive functional groups selected from the group consisting of: When a compound having a (meth) acryloyl group is used as the curable binder resin precursor, the coupling agent is at least one selected from the group consisting of a mercapto group, a (meth) acryloyl group, a vinyl group and a styryl group. It is preferable to have the reactive functional group of. 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 curable binder resin precursor, the silane coupling agent is an epoxy group, an isocyanate group, or a mercapto. It is preferable to have at least one reactive functional group selected from the group consisting of a group and an amino group.

  The surface treatment of the light-scattering particles 18 with a silane coupling agent can be performed by a dry method in which the light-scattering particles 18 are sprayed with a silane coupling agent, or by dispersing the light-scattering particles 18 in a solvent and then performing silane coupling. A wet method or the like in which an agent is added and a reaction is performed is exemplified.

  The light-scattering particles 18 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 luminance before and after the wet heat resistance test can be reduced, and Inorganic particles are preferable because the incident light on the light wavelength conversion sheet 10 can be scattered appropriately and the light wavelength conversion efficiency for the incident light can be improved appropriately.

The 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), magnesium-containing compounds such as MgO and MgF _2. At least one compound selected from the group consisting of compounds, titanium-containing compounds such as TiO ₂ and BaTiO ₃ , antimony-containing compounds such as Sb ₂ O ₅ , silicon-containing compounds such as SiO ₂ , and zinc-containing compounds such as ZnO Particles. Since these inorganic particles can increase the difference in refractive index from the binder resin, they are also preferable from the viewpoint that a large Mie scattering intensity can be obtained. The light-scattering particles 18 may be made of two or more kinds of materials because the light-wavelength conversion sheet 10 can more appropriately improve the light-wavelength conversion efficiency for incident light. Among these, particles of at least one compound selected from the group consisting of aluminum-containing compounds, zirconium-containing compounds, titanium-containing compounds, antimony-containing compounds and silicon-containing compounds are preferable.

<< barrier film >>
The barrier films 12 and 13 are films for suppressing the permeation of moisture and oxygen and protecting the quantum dots 17 from moisture and oxygen. The barrier films 12 and 13 may be only a light-transmissive substrate or a barrier layer having a function of protecting the quantum dots 17 from moisture and oxygen, but as shown in FIG. Of the light transmissive base materials 19 and 20 having a function of protecting the quantum dots 17 from the surface and the barrier layers 21 and 22 having a function of protecting the quantum dots 17 from moisture and oxygen. A multilayer structure is preferred. Although the barrier layers 21 and 22 are provided on the surface of the light transmissive base materials 19 and 20 on the side of the light wavelength conversion layer 11, the surface of the light transmissive base materials 19 and 20 on the side of the light wavelength conversion layer 11 is provided. It may be provided on the surface opposite to.

The oxygen transmission rate (OTR: Oxygen Transmission Rate) of the barrier films 12 and 13 is 1.0 × 10 ⁻¹ cc / m ² / day / atm or less under the conditions of 23 ° C. and 90% Rh (relative humidity). It is preferably 1.0 × 10 ⁻² cc / m ² / day / atm or less. The oxygen permeability can be measured using an oxygen gas permeability measuring device (OX-TRAN 2/21 manufactured by MOCON).

The water vapor transmission rate (WVTR) of the barrier films 12 and 13 is preferably 1.0 × 10 ⁻¹ g / m ² / day or less under the conditions of 40 ° C. and 90% Rh. It is more preferably 1.0 × 10 ⁻² g / m ² / day or less. The water vapor transmission rate can be measured by using a water vapor transmission rate measuring device (DELTAPERM (manufactured by Technolox)).

  When the light-scattering particles are added to the barrier film, the light-scattering particles can be added to the barrier film by kneading the light-scattering particles into the light-transmitting substrate. When adding light scattering particles to the barrier film, it is not necessary to provide the light diffusion layer. In this case, an overcoat layer for preventing scratches may be formed on the side of the light transmissive substrate opposite to the light wavelength conversion layer side.

<< Light-transmissive substrate >>
The light transmissive base materials 19 and 20 are not particularly limited as long as they have light transmissivity. The thickness of the light transmissive substrates 19 and 20 is not particularly limited, but is preferably 10 μm or more and 150 μm or less. If the thickness of the light-transmissive substrate is less than 10 μm, wrinkles and folds may occur during assembly and handling of the light wavelength conversion sheet, and if it exceeds 150 μm, it is suitable for weight reduction and thinning of the display. There is a possibility that there is no. A more preferable lower limit of the thickness of the light transmissive substrates 19 and 20 is 50 μm or more, and a more preferable upper limit thereof is 125 μm or less.

  The average thickness of the light transmissive substrates 19 and 20 can be calculated using, for example, an image of a cross section taken by a scanning electron microscope (SEM), a transmission electron microscope (TEM), or a scanning transmission electron microscope (STEM). .

  Examples of the constituent raw materials of the light-transmissive substrates 19 and 20 include polyester (for example, polyethylene terephthalate and polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyether sulfone, polysulfone. , Polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate, or a thermoplastic resin such as polyurethane. Preferable examples of the constituent material of the base film include polyester (eg, polyethylene terephthalate and polyethylene naphthalate) and cellulose triacetate.

  The light transmissive base materials 19 and 20 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 constituent materials of the same kind, or may be composed of a plurality of layers composed of layers of constituent materials of different types, depending on the application. Good.

<< barrier layer >>
The barrier layers 21 and 22 are layers for protecting the quantum dots 17 from moisture and oxygen. Further, it is preferable that the barrier layers 21 and 22 have a function of improving the adhesiveness with the light wavelength conversion layer 11.

The material for forming the barrier layers 21 and 22 is not particularly limited as long as it has a barrier property, and examples thereof include an inorganic oxide, a metal, and a sol-gel material. Specifically, examples of the inorganic oxide include silicon oxide (SiO _x ), aluminum oxide (Al _n O _m ), titanium oxide (TiO ₂ ), yttrium oxide, boron oxide (B ₂ O ₃ ), and oxidation. Examples of the metal include calcium (CaO) and silicon oxynitride carbide (SiO _x N _y C _z ), examples of the metal include Ti, Al, Mg, and Zr. Examples of the sol-gel material include siloxane. Examples include sol-gel materials and the like. These materials may be used alone or in combination of two or more kinds.

  The thickness of the barrier layers 21 and 22 is not particularly limited, but is preferably 0.01 μm or more and 1 μm or less. If it is less than 0.01 μm, the barrier performance of the barrier layer may be insufficient, and if it exceeds 1 μm, the barrier performance may be easily deteriorated due to cracks in the barrier layer. The more preferable lower limit of the thickness of the barrier layer is 0.03 μm, and the more preferable upper limit thereof is 0.5 μm.

  The thickness of the barrier layer is measured, for example, by measuring the thickness of the barrier layer from an image of a cross section taken randomly at 20 locations with a scanning electron microscope (SEM), a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM). Can be obtained as an average value of the measured thickness of the barrier layer. Further, the barrier layers 21 and 22 may be a single layer or may be a stack of a plurality of layers. When the barrier layer is formed by laminating a plurality of layers, the layers constituting the barrier layer may be directly laminated or laminated.

  The barrier layers 21 and 22 may be formed by, for example, 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, or a roll coating method. Spin coating method and the like can be mentioned. Also, these methods may be combined.

  The barrier layers 21 and 22 are not particularly limited as long as they have the above-mentioned barrier property, but from the viewpoint of the high barrier property and the like, a vapor deposition layer formed by a vapor deposition method is used. preferable.

  Such a vapor deposition layer is not particularly limited in kind as long as it is a layer formed by a vapor deposition method, and may be a layer formed by a CVD method, or by a PVD method. It may be a formed layer.

  When the vapor deposition layer is formed by a CVD method such as a plasma CVD method, it is possible to form a dense layer having a high barrier property, but from the viewpoint of manufacturing efficiency and cost, the vapor deposition layer is formed by the PVD method. Is preferably formed.

  Examples of the PVD method include a vacuum vapor deposition method, a sputtering method, an ion plating method, and the like. Among them, the vacuum vapor deposition method is preferably used from the viewpoint of its barrier property and the like. Examples of the vacuum vapor deposition method include a vacuum vapor deposition method using an electron beam (EB) heating method and a vacuum vapor deposition method using a high frequency dielectric heating method.

As a material for the vapor deposition layer, a metal or an inorganic oxide is preferable, and specifically, a metal such as Ti, Al, Mg, or Zr, silicon oxide, aluminum oxide, silicon oxynitride, aluminum oxynitride, magnesium oxide, or oxide. Examples thereof include inorganic oxides such as zinc, indium oxide, tin oxide, yttrium oxide, B ₂ O ₃ , and CaO. Among them, silicon oxide is preferable because it has high barrier properties and transparency.

  The thickness of the vapor-deposited layer varies depending on the type and composition of the material used and is appropriately selected, but is preferably 0.01 μm or more and 1 μm or less, and more preferably the upper limit is 500 nm. If the thickness of the vapor deposition layer is smaller than the above range, it may be difficult to form a uniform layer, and the barrier properties may not be obtained. Further, when the thickness of the vapor deposition layer is thicker than the above range, the barrier properties may be significantly impaired due to cracks in the vapor deposition layer due to external factors such as pulling after the vapor deposition layer is formed, In addition, it takes time to form and the productivity may be reduced.

  An anchor layer may be formed as a base layer of the barrier layers 21 and 22. Thereby, the barrier property and the weather resistance can be improved. Examples of materials for forming the anchor layer include adhesive resins, inorganic oxides, organic oxides, and metals.

  Examples of the method for forming the anchor layer include a PVD method such as a sputtering method and an ion plating method, a CVD method, a roll coating method, and a spin coating method. Also, these methods may be combined. Among them, in-line coating at the time of film formation is preferable because it has excellent mass productivity and can improve the adhesion of the anchor layer.

<< Light diffusion layer >>
The light diffusion layers 14 and 15 have uneven shapes on their surfaces, and the uneven shapes can diffuse light entering and exiting the light wavelength conversion sheet 10. By providing the light diffusion layers 14 and 15, the light conversion efficiency of the light wavelength conversion sheet 10 can be increased. Further, the light wavelength conversion sheet comes into contact with an optical plate or a lens sheet which will be described later in the backlight device. However, if the light wavelength conversion sheet and the optical plate or the lens sheet stick to each other, the light wavelength conversion sheet and the optical plate Since a pattern called wet-out that is wet with water is formed at the interface between the two, in order to prevent sticking between the light wavelength conversion sheet 10 and the optical plate, as shown in FIG. The surface of the layer 15 opposite to the surface on the side of the light transmissive substrate 20 (light incident surface 10A) and the surface opposite to the surface of the light diffusion layer 14 on the side of the light transmissive substrate 19 (light emitting surface). 10B) preferably has an uneven surface.

  The light diffusion layers 14 and 15 include light scattering particles and a binder resin. Although the volatile organic compound may remain in the light diffusion layers 14 and 15, the remaining amount of the volatile organic compound contained in the light diffusion layers 14 and 15 is contained in a normal light wavelength conversion layer. It is considered to be almost negligible because it is smaller than the remaining amount of volatile organic compounds by one digit or more. Further, in the light diffusion layers 14 and 15, if the volatile organic compound remains, the adhesion with the barrier film and the film hardness of the light diffusion layer may decrease, so that the volatile organic compound remains. The smaller the amount, the better.

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

  The average particle diameter of the light scattering particles is preferably 10 times or more and 20,000 times or less, and more preferably 10 to 5000 times the average particle diameter of the quantum dots 17 described above. When the average particle size of the light scattering particles is less than 10 times the average particle size of the quantum dots, sufficient light diffusibility may not be obtained in the light diffusion layer, and the average particle size of the light scattering particles may be When the average particle diameter of the quantum dots exceeds 20,000 times, the light diffusion performance of the light diffusion layer is excellent, but the light transmittance of the light diffusion layer is likely 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 diameter of the light-scattering particles in the light diffusion layers 14 and 15 is, for example, preferably 1 μm or more and 30 μm or less, and more preferably 1 μm or more and 20 μm or less. When 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 in order to obtain sufficient light diffusivity, the amount of the light scattering particles added Need to be a lot. On the other hand, when the average particle size of the light-scattering particles exceeds 30 μm, the light diffusing performance is excellent, but the light transmittance of the light diffusing layer is likely to be significantly reduced.

  The difference in refractive index between the light scattering particles in the light diffusion layers 14 and 15 and the binder resin is preferably 0.02 or more and 0.15 or less. When it is less than 0.02, the light diffusibility due to the refractive index of the light scattering particles is not optically obtained, and the improvement of the light wavelength conversion efficiency of the light wavelength conversion sheet may be insufficient, and When it exceeds 15, the transmittance of the light diffusion layer may be lowered. The more preferable lower limit of the refractive index difference between the light scattering particles and the binder resin is 0.03 or more, and the more preferable upper limit thereof is 0.12 or more. Either of the refractive index of the light scattering particles and the refractive index of the binder resin 45 may be larger. The refractive index of the light scattering particles and the binder resin can be measured by the same method as the refractive index of the light scattering particles 18 and the binder resin 16.

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

  The light scattering particles in the light diffusion layers 14 and 15 may be particles made of an organic material or particles made of an inorganic material. The organic material forming the light-scattering particles is not particularly limited, and examples thereof include 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. Among them, a crosslinked acrylic resin is preferably used. The inorganic material forming the light-scattering 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. . Among them, silica and / or alumina are preferably used.

<Binder resin>
The binder resin is not particularly limited, but the same binder resin as the binder resin 16 described in the section of the light wavelength conversion layer 11 can be used, and thus the description thereof is omitted here.

<<<< Other light wavelength conversion sheets >>>>
In FIG. 1, the light wavelength conversion sheet 10 in which the light diffusion layer 14, the barrier film 12, the light wavelength conversion layer 11, the barrier film 13, and the light diffusion layer 15 are laminated in this order is shown. The conversion sheet may have the structure shown in FIG. 3 in order to further improve the adhesiveness between the light wavelength conversion layer 11 and the barrier films 12 and 13, and in order to further improve the adhesiveness in FIG. The structure shown in FIG.

  In the light wavelength conversion sheet 30 shown in FIG. 3, the light diffusion layer 14, the barrier film 12, the primer layer 31, the light wavelength conversion layer 11, the primer layer 32, the barrier film 13, and the light diffusion layer 15 are laminated in this order. It is a thing. In FIG. 3, the members designated by the same reference numerals as those in FIG. 1 are the same as the members shown in FIG. 1, and the description thereof will be omitted.

<<< primer layer>
The primer layers 31 and 32 are layers that enhance the adhesiveness between the barrier films 12 and 13 and the light wavelength conversion layer 11, and are arranged between the barrier films 12 and 13 and the light wavelength conversion layer 11, and are also barrier films. 12 and 13 and the light wavelength conversion layer 11 are in close contact with each other. As the constituent material of the primer layers 31 and 32, known materials may be appropriately selected and used, and examples thereof include thermosetting or thermoplastic polyester resins and polyurethane resins. Note that different constituent materials may be used for the primer layers 31 and 32, respectively. The thickness of the primer layers 31 and 32 is not particularly limited, but can be, for example, 100 nm or more and 3 μm or less.

  The light wavelength conversion sheet 40 shown in FIG. 4 includes a light diffusion layer 14, a barrier film 12, an adhesive layer 41, a light transmissive base material 43, a light wavelength conversion layer 11, a light transmissive base material 44, an adhesive layer 42, and a barrier. The film 13 and the light diffusion layer 15 are laminated in this order. The light transmissive substrates 42 and 43 and the adhesive layers 41 and 42 are for further improving the adhesiveness between the barrier films 12 and 13 and the light wavelength conversion layer 11. In FIG. 4, the members denoted by the same reference numerals as those in FIG. 1 are the same as the members shown in FIG. 1, and the description thereof will be omitted.

<< adhesive layer >>
The adhesive layers 41 and 42 are disposed between the barrier films 12 and 13 and the light transmissive base materials 43 and 44, and are in close contact with the barrier films 12 and 13 and the light transmissive base materials 43 and 44. The constituent material of the adhesive layers 41 and 42 is not particularly limited, but examples thereof include polyurethane resin, polyester resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate copolymer, acrylic resin, polyvinyl alcohol. -Based resin, polyvinyl acetal resin, copolymer of ethylene and vinyl acetate or acrylic acid, copolymer of ethylene and styrene and / or butadiene, thermoplastic resin such as olefin resin and / or modified resin thereof, light At least one of a polymer of a polymerizable compound and a thermosetting resin such as an epoxy resin can be used. It is preferable to use acrylic resin, epoxy resin, or polyester resin as a constituent material of the adhesive layers 41 and 42 from the viewpoint of heat resistance and adhesiveness. Note that different constituent materials may be used for the adhesive layers 41 and 42. The thickness of the adhesive layers 41 and 42 is not particularly limited, but can be, for example, 1 μm or more and 20 μm or less.

<< Light-transmissive substrate >>
The light transmissive base materials 43 and 44 are arranged between the adhesive layers 41 and 42 and the light wavelength conversion layer 11, and are in close contact with the adhesive layers 41 and 42 and the light wavelength conversion layer 11. The light transmissive base materials 43 and 44 are the same as the light transmissive base materials 19 and 20, and therefore description thereof is omitted here.

<<< Method of manufacturing light wavelength conversion sheet >>>
The light wavelength conversion sheet 10 can be manufactured, for example, as follows. 5 and 6 are schematic manufacturing process diagrams of the light wavelength conversion sheet according to the present embodiment. First, as shown in FIG. 5A, the barrier layer 21 is formed on one surface of the light transmissive substrate 19 by a vapor deposition method or the like to form a barrier film. Similarly, the barrier layer 22 is formed on one surface of the light transmissive substrate 20 by a vapor deposition method or the like to form the barrier film 13.

  Next, the composition for the light diffusion layer containing the light scattering particles and the curable binder resin precursor is applied to the surface of the barrier film 12 opposite to the surface on the side of the barrier layer 21 and dried to form the light diffusion layer. A coating film of the composition for use is formed. Similarly, a coating film of the composition for a light diffusion layer is formed on the surface of the barrier film 13 opposite to the surface on the barrier layer 22 side.

  Then, the coating film of the composition for the light diffusion layer is cured by light irradiation or the like. Thereby, as shown in FIG. 5B, the light diffusion layer 14 is formed on the surface of the barrier film 12 opposite to the surface on the barrier layer 21 side, and the barrier film 12 with the light diffusion layer 14 is formed. To be done. Further, similarly, the barrier film 13 with the light diffusion layer 15 is formed.

  Next, as shown in FIG. 5C, a curable binder resin precursor is formed on the surface (the surface of the barrier layer 22) opposite to the surface on the light diffusion layer 15 side of the barrier film 13 with the light diffusion layer 15. 23, quantum dots 17, light-scattering particles 18, and a composition 24 for a light wavelength conversion layer containing a volatile organic compound as a solvent is applied, and for example, dried at 40 ° C. to 110 ° C. for a light wavelength conversion layer. A coating film of the composition 24 is formed. Here, since a part of the volatile organic compound contained in the composition for light wavelength conversion layer 24 remains in the light wavelength conversion layer 11 after the formation of the light wavelength conversion layer 11, it is included in the composition for light wavelength conversion layer 24. Examples of the volatile organic compound include the same volatile organic compounds described in the section of the light wavelength conversion sheet 10. Further, when the composition for light wavelength conversion layer 24 is dried at a temperature (drying temperature) exceeding 110 ° C., volatilization of the volatile organic compound causes unevenness on the coated surface, resulting in color unevenness. Is likely to occur.

  Then, as shown in FIG. 6A, the composition for the light wavelength conversion layer is so arranged that the surface of the barrier layer 21 in the barrier film 12 with the light diffusion layer 14 is in contact with the coating film of the composition 24 for the light wavelength conversion layer. The barrier film 12 with the light diffusion layer 14 is arranged on the coating film of the object 24. As a result, the coating film of the light wavelength conversion layer composition 24 is sandwiched between the barrier films 12 and 13.

  Next, as shown in FIG. 6 (B), the coating film of the composition for light wavelength conversion layer 24 is irradiated with light through the barrier film 12 with the light diffusion layer 14 or heat is applied to the curable film. The binder resin precursor 23 is cured to form the light wavelength conversion layer 11, and the light wavelength conversion layer 11 and the barrier films 12 and 13 are integrated. Thereby, the light wavelength conversion sheet 10 shown in FIG. 1 is obtained.

According to this embodiment, since the residual amount of the volatile organic compound contained in the light wavelength conversion sheet 10 is 10 mg / m ² or more and 500 mg / m ² or less, the light wavelength conversion layer 11 and the barrier films 12, 13 are provided. It is possible to suppress the deterioration over time of the quantum dots 17 while ensuring the adhesiveness with. That is, as described above, the quantum dots are deteriorated (deactivated) by water and oxygen in the air. On the other hand, in the present embodiment, since the volatile organic compound in the above range remains in the light wavelength conversion sheet 10, the volatile organic compound remaining in the light wavelength conversion sheet 10 is a moisture content in the air. It serves to protect the quantum dots 17 from oxygen and oxygen. As a result, deactivation of the quantum dots 17 can be suppressed when the light wavelength conversion sheet 10 is used, and thus deterioration of the quantum dots 17 with time can be suppressed. Further, when the residual amount of the volatile organic compound contained in the light wavelength conversion sheet is in the range of 10 mg / m ² or more and 500 mg / m ² or less, the adhesiveness with the barrier film is deteriorated due to curing failure in the light wavelength conversion layer. Can be suppressed. As a result, it is possible to suppress the deterioration of the quantum dots 17 with time while ensuring the adhesiveness between the light wavelength conversion layer 11 and the barrier films 12 and 13.

According to the present embodiment, since the residual amount of the volatile organic compound contained in the light wavelength conversion sheet 10 is 10 mg / m ² or more and 500 mg / m ² or less, the color unevenness of the light wavelength conversion sheet 10 during light emission. Can be suppressed. That is, if the dispersibility of the quantum dots in the light wavelength conversion layer is poor, color unevenness may occur when the light wavelength conversion sheet emits light. On the other hand, in the present embodiment, since the volatile organic compound in the above range remains in the light wavelength conversion sheet 10, the dispersibility of the quantum dots 17 in the light wavelength conversion layer 11 can be improved. Accordingly, it is possible to suppress color unevenness in the light wavelength conversion sheet 10 during light emission.

Even when the remaining amount of the volatile organic compound contained in the light wavelength conversion layer 11 is 10 mg / m ² or more and 500 mg / m ² or less, for the same reason as above, the light wavelength conversion layer 11 and the barrier film 12 , 13 while ensuring the adhesion to the quantum dots 17, and suppressing the color unevenness of the light wavelength conversion sheet 10 during light emission.

  The light wavelength conversion sheet 10 can be used, for example, by incorporating it in a backlight device and a display device. FIG. 7 is a schematic configuration diagram of a display device including the backlight device according to the present embodiment, FIG. 8 is a perspective view of the lens sheet shown in FIG. 7, and FIG. 9 is an I-I of the lens sheet of FIG. FIG. 10 is a cross-sectional view taken along the line, and FIG. 10 is a schematic configuration diagram of another backlight device according to the present embodiment.

<<< Image display device >>>
The image display device 50 shown in FIG. 7 includes a backlight device 60 and a display panel 70 arranged on the light emitting side of the backlight device 60. The display device 50 has a display surface 50A for displaying an image. In the image display device 50 shown in FIG. 7, the surface of the display panel 70 is the display surface 50A.

  The backlight device 60 illuminates the display panel 70 in a planar manner from the back side. The display panel 70 functions as a shutter that controls transmission or blocking of light from the backlight device 60 for each pixel, and is configured to display an image on the display surface 50A.

<< Display panel >>
The display panel 70 shown in FIG. 7 is a liquid crystal display panel, and includes a polarizing plate 71 arranged on the light incident side, a polarizing plate 72 arranged on the light emitting side, and between the polarizing plate 71 and the polarizing plate 72. The liquid crystal cell 73 is arranged. The polarizing plates 71 and 72 decompose the incident light into two orthogonal linearly polarized light components (S-polarized light and P-polarized light) and oscillate in one direction (direction parallel to the transmission axis) (for example, P-polarized light component). It has a function of transmitting polarized light and absorbing a linearly polarized light component (for example, S-polarized light) vibrating in the other direction (direction parallel to the absorption axis) orthogonal to the one direction.

  The liquid crystal cell 73 is configured such that a voltage can be applied to each region forming one pixel. Then, the alignment direction of the liquid crystal molecules in the liquid crystal cell 73 changes depending on whether or not a voltage is applied. As an example, the linearly polarized light component in a specific direction transmitted through the polarizing plate 71 disposed on the light incident side rotates its polarization direction by 90 ° when passing through the liquid crystal cell 73 to which a voltage is applied, while When passing through the liquid crystal cell 73 to which no voltage is applied, the polarization direction is maintained. In this case, depending on the presence / absence of voltage application to the liquid crystal cell 73, the linearly polarized light component that has passed through the polarizing plate 71 and vibrates in a specific direction may be transmitted to the polarizing plate 72 or may be absorbed and blocked by the polarizing plate 72. it can. In this way, the display panel 70 is configured so that transmission or blocking of light from the backlight device 60 can be controlled for each pixel. Note that details of the liquid crystal display panel are described in various publicly known documents (for example, “Flat Panel Display Encyclopedia (Tatsuo Uchida, Hiraki Uchiike), published by the 2001 Industrial Research Committee), and no more here. The detailed description of is omitted.

<< Backlight device >>
The backlight device 60 shown in FIG. 7 is configured as an edge light type backlight device, and includes a light source 80, an optical plate 85 as a light guide plate disposed on the side of the light source 80, and a light exit side of the optical plate 85. The light wavelength conversion sheet 10 arranged on the light wavelength conversion sheet 10, the lens sheet 90 arranged on the light emission side of the light wavelength conversion sheet 10, the lens sheet 95 arranged on the light emission side of the lens sheet 90, and the light emission side of the lens sheet 95. The reflective polarization separation sheet 100 is provided, and the reflection sheet 105 is provided on the opposite side of the optical plate 85 from the light output side. The backlight device 60 includes the optical plate 85, the lens sheets 90 and 95, the reflective polarization separation sheet 100, and the reflective sheet 105, but these sheets and the like may not be provided. In the present specification, the “light emitting side” means the side from which the light emitted from the backlight device is emitted from each member.

  The backlight unit 60 has a light emitting surface that emits light in a planar shape. In the backlight device 60 shown in FIG. 7, the light emitting surface of the reflective polarization separation sheet 100 is the light emitting surface of the backlight device 60.

<Light source>
The light source 80 may be configured in various modes such as a fluorescent lamp such as a linear cold cathode fluorescent lamp, a point light emitting diode (LED), an incandescent lamp, or the like. In the present embodiment, the light source 80 is composed of a large number of point-like light emitting elements arranged in a line on the light incident surface 85C side of the optical plate 85 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 60, the light source 80 can use only a light emitter that emits light in a single wavelength range. For example, as the light source, only a blue light emitting diode that emits blue light with high color purity can be used.

<Optical plate>
The optical plate 85 as the light guide plate is formed in a quadrangular shape in plan view. The optical plate 85 extends between a light exit surface 85A formed by one main surface on the display panel 70 side, a back surface 85B formed by the other main surface facing the light exit surface 85A, and between the light exit surface 85A and the back surface 85B. And a side surface. Of the side surfaces, the side surface on the light source 80 side is a light incident surface 85C that receives light from the light source 80. The light that has entered the optical plate 85 from the light incident surface 85C is guided inside the optical plate 85 in the direction (light guiding direction) that connects the light incident surface 85C and the opposite surface that faces the light incident surface 85C, and then exits. It is emitted from the surface 85A.

  When the light-incident surface 10A of the light wavelength conversion sheet 10 is an uneven surface due to the light-scattering particles of the light diffusion layer 15, as shown in FIG. It is preferable that the surface 10A is optically in close contact with a part (for example, a convex portion) of the surface 10A, and is also separated from another portion (for example, a concave portion) of the light incident surface 10A. In this case, the gap between the light exit surface 85A and the other part of the light entrance surface 10A is an air layer 26. By providing the air layer 26, even when the light wavelength conversion sheet 10 and the optical plate 85 are fixed so that the light exit surface 85A and the light entrance surface 10A are in optical contact with each other, Since it is possible to prevent the plate 85 from sticking, it is possible to suppress the formation of a wetout at the interface between the light wavelength conversion sheet 10 and the optical plate 85. In the present specification, “optically close contact” means a state where the light exit surface of the optical plate and a part of the light entrance surface of the light conversion sheet are in close contact with each other without forming an air layer therebetween. Further, the state where the light wavelength conversion sheet is not attached to the light emitting surface of the optical plate means that the light is emitted from the light emitting surface of the optical plate in the plane direction of the light emitting surface when the fixation of the light wavelength conversion sheet and the optical plate is released. This means that the wavelength conversion sheet can be moved.

  As a material forming the optical plate 85, 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, and the like, and is inexpensive and available. For example, a transparent resin mainly containing one or more of acrylic resin, polystyrene, polycarbonate, polyethylene terephthalate, polyacrylonitrile, and a reactive resin of epoxy acrylate or urethane acrylate (ionizing radiation curable resin, etc.) are preferably used. Can be done. A light diffusing material having a function of diffusing light may be added to the optical plate 85, if necessary. As the light diffusion 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 may be used. it can.

<< lens sheet >>
The lens sheets 90 and 95 have a function of changing the traveling direction of incident light and emitting the light from the light emission side. In the present embodiment, as shown in FIG. 9, in addition to the function (condensing function) of changing the traveling direction of the incident light L3 and causing the light L3 to be emitted from the light output side, the brightness in the front direction is concentrated (condensing function). It has a function of reflecting the incident light L4 and returning it to the light wavelength conversion sheet 10 side (retroreflection function). The lens sheets 90 and 95 include a light transmissive base material 91 and a lens layer 92 provided on one surface of the light transmissive base material 91.

  When the light exit surface 10B of the light wavelength conversion sheet 10 is an uneven surface due to the light scattering particles of the light diffusion layer 14, as shown in FIG. 7, the light entrance surface 90A of the lens sheet 90 is the light exit surface. It is preferable that the portion 10B (for example, a convex portion) is optically in close contact with the light emitting surface 10B and that the portion 10B is apart from another portion (for example, a concave portion) of the light emitting surface 10B. In this case, the gap between the light entrance surface 90A and the other part of the light exit surface 10B is an air layer 27. By providing the air layer 27, even if the light wavelength conversion sheet 10 and the lens sheet 90 are fixed so that the light incident surface 90A and the light exit surface 10B are in optical contact, the light wavelength conversion sheet 10 and the lens are fixed. Since it is possible to prevent the sheet 90 from sticking, it is possible to prevent wetout from being formed at the interface between the light wavelength conversion sheet 10 and the lens sheet 90.

<Light-transmissive substrate>
The light-transmissive base material 91 is similar to the light-transmissive base material 19, and therefore its description is omitted here.

<Lens layer>
As shown in FIGS. 8 and 9, the lens layer 92 includes a sheet-shaped main body 93 and a plurality of unit lenses 94 arranged side by side on the light output side of the main body 93.

  The main body 93 functions as a sheet-shaped member that supports the unit lenses 94. As shown in FIG. 8 and FIG. 9, the unit lenses 94 are arranged on the light output side surface 93A of the main body 93 without a gap. Therefore, the light emitting surfaces 90B and 95B of the lens sheets 90 and 95 are formed by the lens surfaces. On the other hand, as shown in FIG. 9, in the present embodiment, the main body portion 23 has a smooth surface serving as the light incident side surface of the lens layer 92 as the light incident side surface 23B facing the light exit side surface 23A. There is.

  The unit lenses 94 are arranged side by side on the light emitting side surface 93A of the main body 93. As shown in FIG. 8, the unit lenses 94 extend linearly in a direction intersecting the arrangement direction AD of the unit lenses 94, and particularly linearly in the present embodiment. Further, in the present embodiment, the plurality of unit lenses 94 included in one lens sheet 90, 95 extend in parallel with each other. The longitudinal direction LD of the unit lenses 94 of the lens sheets 90 and 94 is orthogonal to the arrangement direction AD of the unit lenses 94 of the lens sheets 90 and 95.

  The unit lens may have a triangular prism shape, or may have a corrugated shape or a bowl shape such as a hemispherical shape. In the present embodiment, as the unit lens, a triangular prism whose width becomes narrower toward the light output side will be described. The shape of a cross section (also referred to as a main cutting surface of the lens sheet) parallel to both the normal direction ND of the sheet surface of the main body 93 and the arrangement direction AD of the unit lenses 94 is a triangular shape protruding toward the light output side. . In particular, from the viewpoint of intensively improving the brightness in the front direction, the cross-sectional shape of the unit lens 94 on the main cutting surface is an isosceles triangular shape, and the apex angle located between the equilateral sides is the light emitting side surface 93A of the main body 93. Each unit lens 94 is configured so as to project from the light emitting side to the light emitting side.

  The unit lens 94 preferably has an apex angle of 80 ° or more and 100 ° or less, and more preferably has an apex angle of about 90 ° from the viewpoint of improving the light utilization efficiency. However, in consideration of damage to the tip of the unit lens when the light wavelength conversion sheet is wound, the tip of the unit lens 94 may be a curved surface.

  The dimensions of the lens sheets 90 and 95 can be set as follows, as an example. First, as a specific example of the unit lenses 94, the arrangement pitch of the unit lenses 94 (corresponding to the width of the unit lenses 94 in the illustrated example) can be set to 10 μm or more and 200 μm or less. However, in recent years, the arraying of the unit lenses 94 is rapidly becoming finer, and it is preferable to set the arraying pitch of the unit lenses 94 to 10 μm or more and 50 μm or less. Further, the protruding height of the unit lens 94 from the main body portion 93 along the normal direction ND to the sheet surfaces of the lens sheets 90 and 95 can be set to 5 μm or more and 100 μm or less. Further, the apex angle θ of the unit lens 94 can be set to 60 ° or more and 120 ° or less.

  As can be understood from FIG. 7, the arrangement direction of the unit lenses 94 of the lens sheet 90 intersects with the arrangement direction of the unit lenses 94 of the lens sheet 95, and more specifically, is orthogonal to each other.

<Reflective polarization separation sheet>
The reflective polarization separation sheet 100 transmits only the first linearly polarized light component (for example, P-polarized light) of the light emitted from the lens sheet 83, and the second linearly polarized light orthogonal to the first linearly polarized light component. It has a function of reflecting a polarized component (for example, S polarized light) without absorbing it. The second linearly polarized light component reflected by the reflective polarization separation sheet 100 is reflected again and the polarization 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 reflection type polarization separation sheet 84 again. Therefore, the reflective polarization separation sheet 100 transmits the first linearly polarized light component of the re-incident light, and the second linearly polarized light component orthogonal to the first linearly polarized light component is reflected again. Hereinafter, by repeating the above process, about 70 to 80% of the light initially emitted from the lens sheet 95 is emitted as the light source light which has become the first linearly polarized light component. Therefore, by making the polarization direction of the first linearly polarized light component (transmission axis component) of the reflective polarization separation sheet 100 and the transmission axis direction of the polarizing plate 71 of the display panel 70 coincide with each other, the light emitted from the backlight device 60 is emitted. Can be used for image formation on the display panel 70. Therefore, even if the light energy input from the light source 80 is the same, it is possible to form an image with higher brightness than in the case where the reflective polarization separation sheet 100 is not arranged, and the energy utilization efficiency of the light source 80 is also improved. improves. In particular, the light reflected by the reflective polarization separation sheet 100 can be wavelength-converted by the light wavelength conversion layer of the light wavelength conversion sheet 10. Therefore, the wavelength conversion efficiency of the light wavelength conversion sheet 10 can be further increased by disposing the reflective polarization separation sheet 100. Therefore, it is possible to expect further improvement in the light use efficiency.

  As the reflective polarization separation sheet 100, "DBEF" (registered trademark) available from 3M can be used. In addition to “DBEF”, a high-brightness polarizing sheet “WRPS”, a wire grid polarizer or the like available from Shinwha Intertek can be used as the reflective polarization separation sheet 84.

<Reflective sheet>
The reflection sheet 105 has a function of reflecting the light leaked from the back surface 85B of the optical plate 85 and making it enter the optical plate 85 again. The reflection sheet 105 is composed of a white scattering reflection sheet, a sheet made of a material having a high reflectance such as metal, a sheet including a thin film (for example, a metal thin film) made of a material having a high reflectance as a surface layer, and the like. obtain. The reflection on the reflection sheet 105 may be regular reflection (specular reflection) or diffuse reflection. When the reflection on the reflection sheet 105 is diffuse reflection, the diffuse reflection may be isotropic diffuse reflection or anisotropic diffuse reflection.

<< Other backlight devices >>
The backlight device incorporating the light wavelength conversion sheet 10 may be a direct type backlight device as shown in FIG. The backlight device 110 shown in FIG. 10 includes a light source 80, an optical plate 111 that receives light from the light source 80 and functions as a light diffusing plate, and a light wavelength conversion sheet 10 that is arranged on the light output side of the optical plate 111. A lens sheet 90 arranged on the light emitting side of the light wavelength conversion sheet 10, a lens sheet 95 arranged on the light emitting side of the lens sheet 90, and a reflection type polarization separation sheet 100 arranged on the light emitting side of the lens sheet 95. I have it. In the present embodiment, the light source 80 is arranged directly below the optical plate 111, not on the side of the optical plate 111. In FIG. 10, members designated by the same reference numerals as those in FIG. 7 are the same as the members shown in FIG. 7, and therefore description thereof will be omitted. The backlight device 110 does not include the reflection sheet 105.

<Optical plate>
The optical plate 111 as a light diffusion plate is formed in a quadrangular shape in plan view. The optical plate 111 has a light entrance surface 111A formed by one main surface on the light source 80 side and a light exit surface 111B formed by the other main surface on the light wavelength conversion sheet 10 side. Light that has entered the optical plate 111 from the light incident surface 111A is diffused in the optical plate 111 and emitted from the light exit surface 111B.

  The optical plate 111 is not particularly limited as long as it can diffuse the light from the light source 80. For example, a plate in which light diffusing particles are dispersed in a transparent material can be used. The transparent material is not particularly limited, but 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 examples thereof include polystyrene resin, styrene-methyl methacrylate copolymer resin, styrene-methacrylic acid copolymer resin, 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. Examples of the light diffusing particles in the optical plate 121 include light diffusing particles generally used as a diffusing plate.

  In the present embodiment, an example in which the light wavelength conversion sheet 10 is incorporated into the backlight devices 60 and 110 has been described, but instead of the light wavelength conversion sheet 10, the light wavelength conversion sheets 30 and 40 are used as the backlight device 60. , 110 may be incorporated.

  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 composition for light wavelength conversion layer>
First, each component was mixed so as to have the composition shown below to obtain a composition for a light wavelength conversion layer.
(Composition 1 for light wavelength conversion layer)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 99 parts by mass Green light emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 3.3 nm: 0.20 parts by mass, red light emitting quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 5. 2 nm): 0.20 part by mass Photoinitiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 1 part by mass Toluene: 3.0 parts by mass

(Composition 2 for light wavelength conversion layer)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 99 parts by mass Green light emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 3.3 nm: 0.20 parts by mass, red light emitting quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 5. 2 nm): 0.20 parts by mass Photoinitiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 1 part by mass Ethanol: 3.0 parts by mass

(Composition 3 for light wavelength conversion layer)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 99 parts by mass Green light emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 3.3 nm: 0.20 parts by mass, red light emitting quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 5. 2 nm): 0.20 part by mass Photoinitiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 1 part by mass Toluene: 1.0 part by mass

(Composition 4 for light wavelength conversion layer)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 99 parts by mass Green light emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 3.3 nm: 0.20 parts by mass, red light emitting quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 5. 2 nm): 0.20 part by mass Photoinitiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 1 part by mass Toluene: 13.0 parts by mass

(Composition 5 for light wavelength conversion layer)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 99 parts by mass Green light emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 3.3 nm: 0.20 parts by mass, red light emitting quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 5. 2 nm): 0.20 parts by mass Photoinitiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 1 part by mass Toluene: 0.5 parts by mass

(Composition 6 for light wavelength conversion layer)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 99 parts by mass Green light emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 3.3 nm: 0.20 parts by mass, red light emitting quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 5. 2 nm): 0.20 parts by mass Photoinitiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 1 part by mass Toluene: 15.0 parts by mass

(Composition 7 for light wavelength conversion layer)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 99 parts by mass Green light emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 3.3 nm: 0.20 parts by mass, red light emitting quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 5. 2 nm): 0.20 parts by mass Photoinitiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 1 part by mass Ethanol: 0.5 parts by mass

(Composition 8 for light wavelength conversion layer)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 99 parts by mass Green light emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 3.3 nm: 0.20 parts by mass, red light emitting quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 5. 2 nm): 0.20 part by mass Photoinitiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 1 part by mass Ethanol: 15.0 parts by mass

(Composition 9 for light wavelength conversion layer)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 99 parts by mass Green light emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 3.3 nm: 0.20 parts by mass, red light emitting quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 5. 2 nm): 0.20 parts by mass Photoinitiator (1-hydroxycyclohexyl phenyl ketone, 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 mixed so as to have the composition shown below to obtain a composition for a light diffusion layer.
(Composition for light diffusion layer)
-Pentaerythritol triacrylate: 99 parts by mass-Light scattering particles (crosslinked polystyrene resin beads, product name "SBX-4", manufactured by Sekisui Plastics Co., Ltd., average particle diameter 4 µm): 158 parts by mass-Photopolymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.): 1 part by mass-solvent (methyl isobutyl ketone: cyclohexanone = 1: 1 (mass ratio)): 170 parts by mass

<Example 1>
First, two polyethylene terephthalate films with a silica vapor deposition layer were prepared by the following method. In a high-frequency sputtering device, by applying high-frequency power having a frequency of 13.56 MHz and a power of 5 kW to electrodes, a discharge is generated in the chamber, and polyethylene terephthalate as a light-transmissive base material having a size of 7 inches and a thickness of 50 μm. On one surface of a film (product name "Lumirror T60", manufactured by Toray Industries, Inc.), a silica vapor deposition layer as a barrier layer made of a target substance (silica) having a thickness of 50 nm and a refractive index of 1.46 is formed, Thereby, two barrier films having a silica vapor deposition layer formed on one surface of the polyethylene terephthalate film were formed.

Then, the composition for a light diffusion layer was applied to the surface of both barrier films opposite to the surface on the silica vapor deposition layer side to form a coating film. Next, the formed coating film was dried by passing dry air at 80 ° C. for 30 seconds to evaporate the solvent in the coating film. Then, the coating film was cured by irradiating with ultraviolet rays so that the integrated light amount was 500 mJ / cm ² , to form a light diffusion layer having a film thickness of 10 μm, and thus a barrier film with a light diffusion layer was formed.

Then, the composition for light wavelength conversion layer 1 was applied to the silica vapor deposition layer side of one of the barrier films with a light diffusion layer and dried at 60 ° C. to form a coating film. Then, the other barrier film with a light diffusion layer was laminated on the surface of the coating film opposite to the surface on the side of the barrier film with a light diffusion layer so that the silica vapor deposition layer was in contact therewith. In this state, the coating film was cured by irradiating it with ultraviolet rays so that the integrated light amount would be 500 mJ / cm ² , thereby forming a 70 μm light wavelength conversion layer in close contact with both barrier films with light diffusion layers. Thereby, the light wavelength conversion sheet according to Example 1 was obtained. The film thickness of the light wavelength conversion layer was determined from the image of the cross section of the light wavelength conversion sheet, which was randomly photographed at 20 locations using a scanning electron microscope (SEM).

<Example 2>
In Example 2, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the composition 2 for light wavelength conversion layer was used instead of the composition 1 for light wavelength conversion layer.

<Example 3>
In Example 3, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the composition 3 for light wavelength conversion layer was used instead of the composition 1 for light wavelength conversion layer.

<Example 4>
In Example 4, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the composition 4 for light wavelength conversion layer was used instead of the composition 1 for light wavelength conversion layer.

<Comparative Example 1>
In Comparative Example 1, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the composition 5 for light wavelength conversion layer was used instead of the composition 1 for light wavelength conversion layer.

<Comparative example 2>
In Comparative Example 2, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the composition 6 for light wavelength conversion layer was used instead of the composition 1 for light wavelength conversion layer.

<Comparative example 3>
In Comparative Example 3, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion layer composition 7 was used in place of the light wavelength conversion layer composition 1.

<Comparative example 4>
In Comparative Example 4, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the composition 8 for light wavelength conversion layer was used instead of the composition 1 for light wavelength conversion layer.

<Comparative Example 5>
In Comparative Example 5, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the composition for light wavelength conversion layer 9 was used in place of the composition for light wavelength conversion layer 1.

<Measurement of residual amount of volatile organic compounds>
The residual amount of the volatile organic compound contained in 1 m ^{2 of the} light wavelength conversion sheet according to the above-mentioned Examples and Comparative Examples was measured by the following method. First, the light wavelength conversion sheet was cut into a size of 1 cm × 2 cm, and the cut light wavelength conversion sheet was put into a 20 ml vial having an internal capacity and sealed. Here, one barrier film is peeled from the light wavelength conversion sheet, and in the state where the peeled barrier film and the remaining portion of the light wavelength conversion sheet where the light wavelength conversion layer is exposed are separated, The peeled barrier film and the rest of the light wavelength conversion sheet) were put in a vial bottle. Then, after heating the sealed vial bottle containing the light wavelength conversion sheet and at 160 ° C. for 15 minutes, a certain amount of gas in the vial bottle was extracted and subjected to gas chromatography (Agilent Technology Co., Ltd. 6890N GC System). ), The volatile organic compound contained in the loaded gas was quantified, and the residual amount (mg / m ² ) of the volatile organic compound contained in 1 m ^{2 of the} light wavelength conversion sheet was calculated. .

<Peel strength measurement>
In the light wavelength conversion sheets according to the above Examples and Comparative Examples, the peel strength was measured as follows. Specifically, first, a test piece having a width of 25 mm was cut out from each light wavelength conversion sheet that had not been subjected to the moist heat resistance test by using a cutter so as not to cause floating at the end. Then, the obtained test piece was fixed to a chucking jig attached to a tensile tester (equipment name “Tensilon”, manufactured by A & D (A & D)), and the test piece was fixed at room temperature. The surface of the polyethylene terephthalate film is pulled at a peeling angle of 180 ° with respect to the surface at a pulling rate of 0.3 m / min, and the polyethylene terephthalate film is peeled from the light wavelength conversion layer. The force (peeling strength) required to peel off the polyethylene terephthalate film from the light wavelength conversion layer was measured. If the peel strength is 2.0 (N / 25 mm) or more, it can be determined that the adhesiveness between the light wavelength conversion layer and the barrier film is secured.

<Brightness change in moist heat resistance test>
In the light wavelength conversion sheets according to the above Examples and Comparative Examples, the light wavelength conversion sheet was allowed to stand in an environment of 60 ° C. and 90% relative humidity for 250 hours to perform a moist-heat resistance test, and a change in luminance before and after the moist-heat resistance test was examined. . Specifically, first, a backlight device of Kindle Fire (registered trademark) HDX7 was prepared, and the light wavelength conversion sheet before the moisture heat resistance test was incorporated into this backlight device. This backlight device includes a blue light emitting diode having an emission peak wavelength of 450 nm, a light diffusing plate, a first prism sheet, and a second prism sheet in this order. The wavelength conversion sheet was arranged between the light diffusion plate and the first prism sheet. The first prism sheet and the second prism sheet include a sheet-shaped main body portion and a plurality of triangular prism-shaped unit prisms arranged side by side on the main body portion and extending in a direction intersecting the arrangement direction. In addition, the apex angle of the unit prism was 90 °. The first 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 second prism sheet.

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

Then, the light wavelength conversion sheet before the moisture heat resistance test was removed from the backlight device, and the light wavelength conversion sheet was subjected to a humidity heat resistance test in which the light wavelength conversion sheet was left for 250 hours in an environment of 60 ° C. and 90% relative humidity. It was After the moisture and heat resistance test, the light wavelength conversion sheet is arranged between the light diffusion plate of the backlight device and the first prism sheet, and blue light is applied to one surface of the light wavelength conversion sheet in the same manner as above. Then, 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 was measured. Then, from these measured luminances, the rate of change in luminance before and after the wet heat resistance test was obtained. Regarding the rate of change in brightness, the rate of change in brightness is A, the brightness of light emitted from the surface of the light wavelength conversion sheet before the humidity and heat resistance test is B, and the brightness of light emitted from the surface of the light wavelength conversion sheet after the resistance to humidity and heat resistance test. Is defined as C, it is calculated by the following formula (2).
A = | C−B | / B × 100 (2)

The results are shown in Table 1 below.

In the light wavelength conversion sheets according to Comparative Examples 1, 3 and 5, the residual amount of the volatile organic compound was too small or almost no volatile organic compound remained, so the peel strength was high, but before and after the moist heat resistance test. The luminance conversion rate was large. Further, in the light wavelength conversion sheets according to Comparative Examples 2 and 4, the residual amount of the volatile organic compound was too large, so that curing failure occurred and the peel strength was low. In Comparative Example 5, the residual amount of the volatile organic compound in the light wavelength conversion sheet is 0.5 mg / m ² , which is the residual amount of the volatile organic compound contained in the light diffusion layer. The residual amount of the volatile organic compound contained in the light diffusion layer is smaller than the residual amount of the volatile organic compound contained in the normal light wavelength conversion layer by one digit or more, and thus can be almost ignored.

  On the other hand, in the light wavelength conversion sheets according to Examples 1 to 4, since the volatile organic compound remained moderately, the peel strength was lower than that of Comparative Example 5, but 2.0 (N / 25 mm). ) The above peel strength was achieved. Moreover, in the light wavelength conversion sheets according to Examples 1 to 4, the luminance conversion rates before and after the wet heat resistance test were small. Thereby, in Examples 1 to 4, it was confirmed that the temporal change of the quantum dots can be suppressed while ensuring the adhesiveness between the light wavelength conversion layer and the barrier film.

10, 30, 40 ... Light wavelength conversion sheet 11 ... Light wavelength conversion layers 12, 13 ... Barrier film 16 ... Binder resin 17 ... Quantum dots 19, 20 ... Light transmissive base materials 21, 22 ... Barrier layer 50 ... Display device 60 , 110 ... Backlight device 70 ... Display panel 80 ... Light source

Claims (8)

A light wavelength conversion sheet,
A binder resin, and an optical wavelength conversion layer containing quantum dots dispersed in the binder resin,
A barrier film which is provided on both sides of the light wavelength conversion layer and which suppresses the permeation of moisture and oxygen,
The light wavelength conversion sheet, wherein the residual amount of the volatile organic compound contained in the light wavelength conversion sheet per unit area is 10 mg / m ² or more and 500 mg / m ² or less.   The light wavelength conversion sheet according to claim 1, wherein the volatile organic compound is a non-polar volatile organic compound.   The light wavelength conversion sheet according to claim 1, wherein the volatile organic compound is an organic compound having a boiling point of 75 ° C or higher.   The light wavelength conversion sheet according to claim 1, wherein the barrier film comprises a light transmissive base material and a barrier layer provided on one surface of the light transmissive base material.   The light wavelength conversion sheet according to claim 1, wherein the light wavelength conversion layer has a thickness of 10 μm or more and 150 μm or less. A light source,
The light wavelength conversion sheet according to claim 1, which receives light from the light source,
A backlight device comprising:   7. The light source emits blue light, and the quantum dots include first quantum dots that convert the blue light into green light, and second quantum dots that convert the blue light into red light. Backlight device described. A backlight device according to claim 6;
An image display device, comprising: a display panel disposed on a light emitting side of the backlight device.

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