JP2018157085A - Light wavelength conversion composition, light wavelength conversion member, light emitting device, backlight device, and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light wavelength conversion composition having excellent heat resistance after curing, a light wavelength conversion member made of a cured product of such a light wavelength conversion composition, a light emitting device provided with such a light wavelength conversion member, and a backlight. A device and an image display device are provided. A light wavelength conversion member 13 composed of a quantum dot 18 and a cured product of a light wavelength conversion composition containing a silicone resin containing a nitrogen atom. [Selection diagram] Fig. 1

Description

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

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

  Currently, in order to improve color reproducibility, it has been studied to incorporate an optical wavelength conversion member including quantum dots and a binder resin into a backlight device (see, for example, Patent Document 1). The quantum dots can absorb light (primary light) and emit light of different wavelengths (secondary light), and the wavelength of light emitted by the quantum dots mainly depends on the particle diameter of the quantum dots. Therefore, in the backlight device in which the light wavelength conversion member is incorporated, various colors can be reproduced using a light emitting element that projects light in a single wavelength region. For example, when a light source that emits blue light is used, the light wavelength conversion member can absorb blue light and emit green light and red light. Since a backlight device incorporating such a light wavelength conversion member has excellent color purity, color reproducibility can be improved in an image display device using this backlight device.

JP 2013-218953 A

  As a method of incorporating the light wavelength conversion member into the backlight device, there is an on-chip method of incorporating the light wavelength conversion member into the light source. However, when the light wavelength conversion member is incorporated in the light source in the on-chip method, the quantum dots in the light wavelength conversion member may be deteriorated by heat generated from a light emitting element such as an LED element.

  The present invention has been made to solve the above problems. That is, a light wavelength conversion composition having excellent heat resistance, a light wavelength conversion member made of a cured product of such a light wavelength conversion composition, a light emitting device, a backlight device, and an image provided with such a light wavelength conversion member An object is to provide a display device.

  The inventors of the present invention have made extensive studies on the above problems, and by including a specific silicone resin in addition to the quantum dots in the light wavelength conversion composition, the light wavelength capable of suppressing the deterioration of the quantum dots due to heat. It has been found that a conversion composition is obtained. The present invention has been completed based on such findings.

  According to one aspect of the present invention, there is provided a light wavelength conversion composition comprising quantum dots and a curable silicone resin containing a nitrogen atom.

  In the light wavelength conversion composition, the silicone resin may have at least one of a polyimide structure, a polyamide structure, and a polyamideimide structure.

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

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

  In the light emitting device, the light emitting element may be an LED element.

  In the light emitting device, the light wavelength conversion member may cover the light emitting element.

  In the light emitting device, the light emitting device may further include a sealing member that is provided between the light emitting element and the light wavelength conversion member and seals the light emitting element.

  In the light emitting device, the light output surface of the light wavelength conversion member may be a lens surface.

  According to another aspect of the present invention, a backlight device including the light emitting device is provided.

  According to another aspect of the present invention, there is provided an image display device comprising the backlight device and a display panel disposed on the light output side of the backlight device.

  According to one aspect of the present invention, since the curable silicone resin containing a nitrogen atom is included, an optical wavelength conversion composition having excellent heat resistance can be provided. According to another aspect of the present invention, it is possible to provide a light wavelength changing member having excellent heat resistance, and a light emitting device, a backlight device, and an image display device provided with such a light wavelength conversion member.

It is a schematic block diagram of the light-emitting device which concerns on embodiment. It is a schematic block diagram of the other light-emitting device which concerns on embodiment. 1 is a schematic configuration diagram of an image display device according to an embodiment. FIG. 4 is a perspective view of the lens sheet shown in FIG. 3. It is a schematic block diagram of the other backlight apparatus which concerns on embodiment.

  Hereinafter, a light wavelength conversion composition, a light wavelength conversion member, a light emitting device, a backlight device, and an image display device according to embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a light emitting device according to this embodiment, and FIG. 2 is a schematic configuration diagram of another light emitting device according to this embodiment.

<<< Light wavelength conversion composition >>>
The light wavelength conversion composition is a composition for converting incident light into light of another wavelength. The light wavelength conversion composition contains quantum dots and a silicone resin containing nitrogen atoms (hereinafter, this silicone resin is referred to as “specific silicone resin”). The light wavelength conversion composition may contain a solvent, light scattering particles, a phosphor, and the like in addition to the quantum dots and the silicone resin. For example, when using a light wavelength conversion composition as a light wavelength conversion sheet, it is preferable that a light wavelength conversion composition contains a light-scattering particle. In the present specification, the “sheet” is a concept including a member called a film.

  The light wavelength conversion composition may be used in the state of a composition, or the light wavelength conversion composition may be cured and used in the state of a light wavelength conversion member described later which is a cured product.

  The viscosity of the light wavelength conversion composition is preferably 100 mPa · s or more and 10,000 mPa · s or less. When the viscosity of the light wavelength conversion composition is 100 mPa · s or more, the shape after coating can be easily maintained, and when it is 10000 mPa · s or less, the light wavelength conversion composition is easily applied. And good leveling properties can be obtained.

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

  Specifically, the energy band gap of the quantum dot increases as the particle size decreases. That is, as the crystal size decreases, the light emission of the quantum dots shifts to the blue side, that is, to the high energy side. Therefore, by changing the particle diameter of the quantum dots, the emission wavelength can be adjusted over the entire wavelength range of the ultraviolet region, the visible region, and the infrared region. For example, when the quantum dot is composed of CdSe / ZnS described later, blue light is emitted when the particle diameter of the quantum dot is 2.0 nm or more and 4.0 nm or less, and the particle diameter of the quantum dot is 3.0 nm. When it is 6.0 nm or less, green light is emitted, and when the particle size of the quantum dots is 4.5 nm or more and 10.0 nm or less, red light is emitted. In this specification, “blue light” is light having a wavelength range of 380 nm or more and less than 480 nm, “green light” is light having a wavelength range of 480 nm or more and less than 590 nm, and “red light” is It is light having a wavelength range of 590 nm to 750 nm. In the above, the particle diameter range of the quantum dot emitting blue light and the particle diameter range of the quantum dot emitting green light partially overlap, and the particle diameter of the quantum dot emitting green light and the red light Although the range of the particle diameter of the emitted quantum dots partially overlaps, even if the quantum dots have the same particle diameter, the emission color may vary depending on the size of the quantum dot core, so there is no contradiction. Not what you want. The average particle size of the quantum dots 18 can be obtained by measuring the particle size of 20 quantum dots in cross-sectional observation of the light wavelength conversion particles with a transmission electron microscope or a scanning transmission electron microscope, and calculating the average value. it can.

  As the quantum dot, one kind of quantum dot may be used, but it is also possible to use two or more kinds of quantum dots each having an emission band in a single wavelength region by different particle diameters or materials. . Specifically, the light wavelength conversion composition may include a first quantum dot and a second quantum dot having an emission band in a wavelength region different from that of the first quantum dot.

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

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

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

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

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

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

  The shape of the quantum dot is not particularly limited, and may be, for example, a spherical shape, a rod shape, a disk shape, or other shapes. The particle diameter of the quantum dots can be a true spherical value having the same volume when the shape of the quantum dots is not spherical.

  Information such as the particle diameter, average particle diameter, shape, and dispersion state of the quantum dots can be obtained by a transmission electron microscope or a scanning transmission electron microscope. The average particle diameter of the quantum dots can be obtained as an average value of the diameters of 20 quantum dots measured by observation with a transmission electron microscope or a scanning transmission electron microscope. In addition, since the emission color of the quantum dot changes depending on the particle diameter, the particle diameter of the quantum dot can be obtained from confirmation of the emission color of the quantum dot. In addition, the crystal structure and crystallite size of the quantum dots can be known by X-ray crystal diffraction (XRD). Furthermore, the information regarding the particle diameter etc. of a quantum dot can also be obtained with an ultraviolet-visible (UV-Vis) absorption spectrum.

  The content of the quantum dots with respect to the total solid content of the light wavelength conversion composition is preferably 0.01% by mass or more and 2% by mass or less, and more preferably 0.03% by mass or more and 1% by mass or less. . If the quantum dot content is 0.01% by mass or more, sufficient emission intensity can be obtained, and if the quantum dot content is 2% by mass or less, sufficient transmitted light intensity of excitation light is obtained. Can be obtained.

<< Specific silicone resin >>
A specific silicone resin contains a nitrogen atom. Although it will not specifically limit if it is a silicone resin containing a nitrogen atom as a specific silicone resin, For example, the silicone resin which has at least any one structure of a polyimide structure, a polyamide structure, and a polyamideimide structure is preferable. Hereinafter, a silicone resin having a polyimide structure is referred to as a polyimide silicone resin, a silicone resin having a polyamide structure is referred to as a polyamide silicone resin, and a silicone resin having a polyamideimide structure is referred to as a polyamideimide silicone resin. The “polyamide” in the present specification is a concept including an aromatic polyamide (aramid). The specific silicone resin is preferably a polyimide silicone resin from the viewpoint of heat resistance, mechanical properties, and solvent resistance.

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

  The specific silicone resin preferably has a thermosetting group from the viewpoint of obtaining a light wavelength conversion member. As the thermosetting group, a carboxyl group, an amino group, an epoxy group, a hydroxyl group, etc. are common, but in view of the polyimide production process, a carboxyl group or a phenol group is preferable in that it does not easily react with an amino group. .

<Polyimide silicone resin>
The polyimide silicone resin has a polyimide structure (part) and a silicone structure (part). Although the ratio of a polyimide structure and a silicone structure is not specifically limited, 5: 95-80: 20 are preferable by mass ratio, and 10: 90-60: 40 is more preferable.

  The weight average molecular weight of the polyimide silicone resin is preferably 800 or more and 300,000 or less. When the weight average molecular weight of the polyimide silicone resin is 800 or more, the flexibility is excellent. When the weight average molecular weight is 300000 or less, the tackiness is lost, so that dust is difficult to adhere. In this specification, the “weight average molecular weight” is a value obtained by dissolving in a solvent such as tetrahydrofuran (THF) and converting to polystyrene by a conventionally known gel permeation chromatography (GPC) method. The lower limit of the weight average molecular weight of the polyimide silicone resin is more preferably 3000 or more, and the upper limit is more preferably 200000 or less.

  A polyimide silicone resin can be obtained, for example, by reacting a tetracarboxylic acid with a diamine having a siloxane bond. Polyimide silicone resin can be produced by a one-step polymerization method in which tetracarboxylic acid and diamine are used in an equimolar number in the presence of a solvent and polymerized only at a high temperature. First, an amic acid is synthesized at a low temperature and then at a high temperature. It can also be produced by a two-stage polymerization method in which imidization is performed. The molecular weight of the polyimide silicone resin, the ratio between the polyimide structure and the silicone structure, and the like can be appropriately adjusted by controlling the types and reaction conditions of the tetracarboxylic acid and diamine that are the raw materials.

  Examples of commercially available polyimide silicone resins include SCR-1012 and SCR-1016 (both manufactured by Shin-Etsu Chemical Co., Ltd.).

  In curing the polyimide silicone resin, for example, heating is performed at a temperature of 80 ° C. or higher and 300 ° C. or lower, preferably 100 ° C. or higher and 250 ° C. or lower. When curing at 80 ° C. or higher during curing, the thermosetting does not take too long, and when heated at 300 ° C. or lower, the polyimide silicone resin does not deteriorate.

<Polyamide silicone resin>
The polyamide silicone resin has a polyamide structure (part) and a silicone structure (part). The ratio of the polyamide structure and the silicone structure is not particularly limited, but is preferably 5:95 to 80:20 and more preferably 10:90 to 60:40 in terms of mass ratio.

  The weight average molecular weight of the polyamide silicone resin is preferably 800 or more and 300,000 or less. If the weight average molecular weight of the polyamide silicone resin is 800 or more, the flexibility is excellent, and if it is 300,000 or less, the tackiness is lost, so that dust does not easily adhere.

  The polyamide silicone resin can be obtained, for example, by polycondensation of an aliphatic or aromatic dicarboxylic acid or a reactive derivative thereof with an amino group-modified diorganopolysiloxane or an aliphatic or aromatic diamine. The molecular weight of the polyamide silicone resin, the ratio between the polyamide structure and the silicone structure, and the like can be adjusted as appropriate by controlling the type and reaction conditions of the dicarboxylic acid and diamine that are the raw materials.

<Polyamideimide silicone resin>
The polyamide-imide silicone resin has a polyamide structure (part), a polyimide structure (part), and a silicone structure (part).

  The weight average molecular weight of the polyamide-imide silicone resin is preferably 800 or more and 300000 or less. If the weight average molecular weight of the polyamide silicone resin is 800 or more, the flexibility is excellent, and if it is 300,000 or less, the tackiness is lost, so that dust does not easily adhere.

  The polyamide-imide silicone resin can be obtained, for example, by copolymerizing a polyamide-imide resin and a polyfunctional silicone compound, or by modifying the polyamide-imide resin with silicone. The polyamide-imide silicone resin can also be obtained by polycondensation of an aromatic tricarboxylic acid or a reactive acid derivative thereof, an aromatic diamine, and diaminosiloxane.

<< Solvent >>
Examples of the solvent include, but are not limited to, alcohols such as methanol, ethanol, propanol, and isopropyl alcohol; ketones such as methyl ethyl ketone and methyl isobutyl ketone, toluene, and cyclohexane.

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

  The average particle size of the light-scattering particles is preferably 20 times or more and 2000 times or less, more preferably 50 times or more and 1000 times or less than the average particle size of the quantum dots. If the average particle size of the light scattering particles is less than 20 times the average particle size of the quantum dots, sufficient light scattering performance may not be obtained in the light wavelength conversion member, and the average particle size of the light scattering particles is If the average particle diameter exceeds 2000 times the average particle diameter of the quantum dots, the number of light-scattering particles decreases even if the addition amount is the same, so that the number of scattering points may decrease and a sufficient light scattering effect may not be obtained. . In addition, the average particle diameter of light-scattering particle | grains can be measured by the method similar to the average particle diameter of the quantum dot mentioned above.

  Further, the average particle diameter of the light scattering particles is preferably 1/300 or more and 1/20 or less, more preferably 1/200 or more and 1/30 or less, of the average film thickness of the light wavelength conversion member described later. preferable. If the average particle diameter of the light scattering particles is less than 1/300 of the average film thickness of the light wavelength conversion member, sufficient light scattering performance may not be obtained in the light wavelength conversion member. When the particle diameter exceeds 1/20 of the average film thickness of the light wavelength conversion member, the ratio of light scattering particles to the light wavelength conversion member is decreased even if the addition amount is the same. Light scattering effect cannot be obtained.

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

  The shape of the light-scattering particles is not particularly limited. For example, the shape is spherical (true sphere, approximately true sphere, elliptical sphere, etc.), polyhedral, rod (column, prism, etc.), flat plate, flake, irregular shape. Etc. In addition, when the shape of the light scattering particles is not spherical, the particle diameter of the light scattering particles can be a true spherical value having the same volume.

  The light-scattering particles may be organic particles such as acrylic resin particles, styrene resin particles, melamine resin particles, and urethane resin particles, but the luminance change rate before and after the energization heat test can be reduced. Inorganic particles are preferred because it is possible to suitably scatter incident light on the light wavelength conversion sheet, and to improve the light wavelength conversion efficiency with respect to the incident light.

Inorganic particles include aluminum-containing compounds such as Al ₂ O ₃ , zirconium-containing compounds such as ZrO ₂ , tin-containing compounds such as antimony-doped tin oxide (ATO) and indium tin oxide (ITO), and magnesium-containing materials such as MgO and MgF _2. At least one compound selected from the group consisting of compounds, titanium-containing compounds such as TiO ₂ and BaTiO ₃ , antimony-containing compounds such as Sb ₂ O ₅ , silicon-containing compounds such as SiO ₂ , and zinc-containing compounds such as ZnO Particles. Since these inorganic particles can increase the difference in refractive index with the binder resin, they are also preferable from the viewpoint of obtaining a large Mie scattering intensity. Since the light wavelength conversion efficiency with respect to incident light by the light emitting device 10 can be improved more suitably, the light scattering particles may be made of two or more kinds of materials.

  The content of the light-scattering particles with respect to the total solid mass of the light wavelength conversion composition is preferably 1% by mass or more and 50% by mass or less, and more preferably 3% by mass or more and 30% by mass or less. If the content of the light scattering particles is less than 1% by mass, the light scattering effect may not be sufficiently obtained, and if the content of the light scattering particles exceeds 50% by mass, Mie scattering occurs. Since it becomes difficult, the light scattering effect may not be sufficiently obtained, and the processability may be deteriorated because there are too many light scattering particles.

<< phosphor >>
The phosphor is appropriately selected and used in order to obtain light having a desired color. As the phosphor, a generally known phosphor can be used.

<<< Light wavelength conversion member >>>
The light wavelength conversion member is a member made of a cured product of the light wavelength conversion composition. The shape of the light wavelength conversion member can be appropriately changed depending on the location where the light wavelength conversion member is incorporated. The light wavelength conversion member can be obtained by using a specific curable silicone resin, that is, a specific silicone resin having a thermosetting group.

<<< Light-emitting device >>>
A light-emitting device 10 shown in FIG. 1 is a light-emitting element package, and includes a package body 11 having a recess 11A, a light-emitting element 12 disposed in the recess 11A of the package body 11, and light that receives light from the light-emitting element 12. A wavelength conversion member 13, an electrode layer 14, and a wire 15 are provided. In addition, the light-emitting device 10 should just be provided with the light emitting element 12 and the optical wavelength conversion member 13, and does not need to be provided with another member. Moreover, although the light-emitting device 10 is a display-mounting type light-emitting device, for example, a bullet-type light-emitting device may be used. The light emitting device only needs to include one or more light emitting elements, and may include a plurality of light emitting elements.

<< Package body >>
The package body 11 includes a substrate 11 </ b> B and a reflecting member 11 </ b> C disposed on the surface of the substrate 11 </ b> B on the light emitting element 12 side and disposed so as to surround the light emitting element 12. The reflecting member 11 </ b> C has high reflectivity mainly with respect to light in a visible light wavelength region with a wavelength of 380 nm or more and 780 nm or less. The reflection member 11C is not particularly limited as long as it is a member having a reflection surface for reflecting light from the light emitting element 12 and guiding it in a predetermined direction. For example, foam type white polyester, white polyethylene resin, silver vapor deposition polyester, etc. It can be formed from

<< Light Emitting Element >>
Examples of the light emitting element 12 include a light emitting diode element (LED element) and a laser diode element (LD element). As the light-emitting element, a light-emitting element that emits light in a single wavelength region can be used. For example, as the light-emitting element 12, a blue light-emitting diode (blue LED) that emits blue light with high color purity can be used. The light emitting element 12 is electrically connected to the electrode layer 14 through a wire 15.

<< Light wavelength conversion member >>
The light wavelength conversion member 13 is a cured product of the light wavelength conversion composition. Therefore, the light wavelength conversion member 13 includes the quantum dots 18 and the binder resin 19 made of a cured product of the specific silicone resin. The quantum dot 18 shown in FIG. 1 includes a first quantum dot 18A and a second quantum dot 18B having an emission band in a wavelength region different from that of the first quantum dot 18A. For example, when a blue light emitting diode is used as the light emitting element 12, from the viewpoint of expanding the color gamut, a quantum dot that converts blue light into green light is used as the first quantum dot 18A, and the second quantum dot 18B is used. It is preferable to use quantum dots that convert blue light into red light. Since the quantum dot 18 and the specific silicone resin are the same as the quantum dot and the specific silicone resin described in the column of the light wavelength conversion composition, the description thereof is omitted here.

  The light wavelength conversion member 13 is filled in the recess 11 </ b> A and covers the light emitting element 12 to seal the light emitting element 12. That is, the light wavelength conversion member 13 also functions as a sealing member that seals the light emitting element 12.

  The thickness of the light wavelength conversion member 13 is preferably 0.1 mm or more and 10 mm or less. If the thickness of the light wavelength conversion member 13 is 0.1 mm or more, the wavelength conversion of light from the light emitting element 12 can be reliably performed, and the light emitting element 12 can be reliably sealed. The thickness of the optical wavelength conversion member 13 is obtained by photographing a cross section of the optical wavelength conversion member 13 with an optical microscope such as a macroscope having a length measurement function, and the thickness of the optical wavelength conversion member 13 is 20 in the image of the cross section. Measure the points and use the average value of the film thicknesses at the 20 points.

  Since the light wavelength conversion member 13 covers the light emitting element 12, it is in contact with the light emitting element 12. However, the light wavelength conversion member 13 may not be in contact with the light emitting element as long as it receives light from the light emitting element in the light emitting device. Further, the light output side surface 13A of the light wavelength conversion member 13 shown in FIG. 1 is a flat surface, but may be a lens surface as described later.

<<< Other light emitting devices >>>
The light-emitting device includes a light-emitting element 12 as shown in FIG. 2, a light wavelength conversion member 21 that receives light from the light-emitting element 12, and a sealing member 22 that is positioned between the light-emitting element 12 and the light wavelength conversion member 21. The light-emitting device 20 may be provided. By interposing the sealing member 22 between the light emitting element 12 and the light wavelength conversion member 21, the light wavelength conversion member 21 can be separated from the light emitting element 12, thereby further suppressing deterioration of the quantum dots 18 due to heat. be able to. In FIG. 2, members denoted by the same reference numerals as those in FIG. 1 are the same as the members shown in FIG.

  The distance from the surface 12A of the light emitting element 12 to the light wavelength conversion member 21 is preferably 0.1 mm or more and 10 mm or less. If this distance is 0.1 mm or more, the quantum dot 18 can be moved away from the light emitting element 12, so that the influence of heat from the light emitting element 12 is reduced, deterioration of the quantum dot 18 can be suppressed, and at 10 mm or less. If so, the light emitting device 20 can be thinned. In the present specification, the “distance from the surface of the light emitting element to the light wavelength conversion member” means the distance from the surface of the light emitting element to the surface of the light wavelength conversion member on the light emitting element side.

<< Light wavelength conversion member >>
The light wavelength conversion member 21 is a cured product of the light wavelength conversion composition. The surface 21A on the light output side of the light wavelength conversion member 21 is a lens surface. The “lens surface” in this specification means a surface that acts as a lens. The lens surface may be either a lens surface having a condensing function or a lens surface having a light diffusion function. By making the surface 21A of the light wavelength conversion member 21 a lens surface having a condensing function, the light extraction efficiency to the front surface can be improved. Further, in the case of a direct type backlight device, it is desired to improve the light diffusibility of the light emitting device in order to reduce luminance unevenness, but the surface 21A of the light wavelength conversion member 21 is a lens having a light diffusing function. Since the light diffusibility can be improved by using the surface, it is particularly suitable for a direct type backlight device.

  The surface 21A of the light wavelength conversion member 21 may have a bowl shape such as a hemisphere. In this case, the light wavelength conversion member 21 functions as a microlens or the like.

<< Sealing member >>
Since the heat | fever of the light emitting element 12 is added, it is preferable that the sealing member 22 is comprised from resin excellent in heat resistance. Such a resin is not particularly limited, but a silicone resin is preferable. The sealing member 22 may use the specific silicone resin, but may be other silicone resins.

  The thickness of the sealing member 22 is preferably 0.1 mm or greater and 10 mm or less. If the thickness of the sealing member 22 is 0.1 mm or more, the quantum dot 18 can be moved away from the light emitting element 12, so that the influence of heat from the light emitting element 12 is reduced and the deterioration of the quantum dot 18 is further suppressed. In addition, if the thickness is 10 mm or less, the light emitting device 20 can be thinned.

  The light emitting devices 10 and 20 can be used as a light source by being incorporated in a backlight device and an image display device. Hereinafter, an example in which the light emitting device 10 is incorporated in a backlight device and an image display device will be described. 3 is a schematic configuration diagram of an image display device including the backlight device according to the present embodiment, FIG. 4 is a perspective view of the lens sheet shown in FIG. 1, and FIG. 5 is another backlight according to the present embodiment. It is a schematic block diagram of a light apparatus.

<<< Image display device >>>
The image display device 30 shown in FIG. 3 includes a backlight device 40 and a display panel 100 arranged on the light output side of the backlight device 40. The image display device 30 has a display surface 30A for displaying an image. In the image display device 30 shown in FIG. 3, the surface of the display panel 100 is the display surface 30A.

  The backlight device 40 illuminates the display panel 100 in a planar shape from the back side. The display panel 120 functions as a shutter that controls transmission or blocking of light from the backlight device 40 for each pixel, and is configured to display an image on the display surface 30A.

<< Display panel >>
A display panel 100 shown in FIG. 3 is a liquid crystal display panel, and a polarizing plate 101 disposed on the light incident side, a polarizing plate 102 disposed on the light exit side, and between the polarizing plate 101 and the polarizing plate 102. The liquid crystal cell 103 is provided. Polarizing plates 101 and 102 decompose incident light into two linearly polarized light components (S-polarized light and P-polarized light) orthogonal to each other, and vibrate in one direction (direction parallel to the transmission axis) (for example, P It has a function of transmitting a linearly polarized component (for example, S-polarized light) that transmits polarized light and vibrates in the other direction (direction parallel to the absorption axis) perpendicular to the one direction.

<< Backlight device >>
The backlight device 40 shown in FIG. 3 is configured as an edge light type backlight device, and includes a light emitting device 10, an optical plate 50 as a light guide plate disposed on the side of the light emitting device 10, and an optical plate 50. The lens sheet 60 disposed on the light exit side, the lens sheet 65 disposed on the light exit side of the lens sheet 60, the reflective polarization separation sheet 70 disposed on the light exit side of the lens sheet 65, and the light exit side of the optical plate 50 And a reflection sheet 80 arranged on the opposite side. The backlight device 40 includes the optical plate 50, the lens sheets 60 and 65, the reflective polarization separation sheet 70, and the reflective sheet 80, but these sheets and the like may not be provided. In the present specification, the “light exit side” means a side from which light is emitted from each member in the direction of exiting the backlight device.

  The backlight device 40 has a light emitting surface 40A that emits light in a planar shape. In the backlight device 40 shown in FIG. 3, the light exit surface of the reflective polarization separation sheet 70 is the light emitting surface 40 </ b> A of the backlight device 40.

<Light emitting device>
The light emitting device 10 is disposed such that the surface 13A of the light wavelength conversion member 13 is on the light incident surface 50C side described later of the optical plate 50. The light emitting device 10 is provided in a plurality of lines along a light incident surface 50C, which will be described later, of the optical plate 50.

<Optical plate>
The optical plate 50 as the light guide plate has a quadrangular shape in plan view. The optical plate 50 extends between a light exit surface 50A formed by one main surface on the display panel 100 side, a back surface 50B composed of the other main surface facing the light output surface 50A, and the light output surface 50A and the back surface 50B. And have side faces. Of the side surfaces, the side surface on the light emitting device 10 side is a light incident surface 50 </ b> C that receives light from the light emitting device 10. The light that has entered the optical plate 50 from the light incident surface 50C is guided through the optical plate in a direction (light guide direction) connecting the light incident surface 50C and the opposite surface facing the light incident surface 50C. It is emitted from 50A.

  As a material constituting the optical plate 50, a material that is widely used as a material for an optical sheet incorporated in an image display device, has excellent mechanical characteristics, optical characteristics, stability, workability, and the like, and can be obtained at low cost. For example, transparent resins mainly composed of one or more of acrylic resin, polystyrene, polycarbonate, polyethylene terephthalate, polyacrylonitrile, etc., and epoxy acrylate or urethane acrylate reactive resins (ionizing radiation curable resins, etc.) are preferably used. Can be done. If necessary, a light diffusing material having a function of diffusing light can be added to the optical plate 50. As the light diffusing material, for example, particles made of a transparent material such as silica (silicon dioxide), alumina (aluminum oxide), acrylic resin, polycarbonate resin, or silicone resin having an average particle diameter of 0.5 μm to 100 μm are used. it can.

<< Lens sheet >>
The lens sheets 60 and 65 have a function of changing the traveling direction of the incident light and emitting it from the light output side. In the present embodiment, the light that has a large incident angle is changed from the traveling direction of the light to be emitted from the light exit side, and the light that has a small incident angle is reflected along with the function that concentrates the brightness in the front direction (condensing function). And having a function of returning to the optical plate 50 side (retroreflection function). The lens sheets 60 and 65 include a light transmissive substrate 61 and a lens layer 62 provided on one surface of the light transmissive substrate 61.

<Light transmissive substrate>
Examples of constituent materials of the light transmissive substrate 61 include polyester (for example, polyethylene terephthalate, polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, and polypropylene. , Thermoplastic resins such as polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate, and polyurethane.

<Lens layer>
As illustrated in FIG. 4, the lens layer 62 includes a sheet-like main body 63 and a plurality of unit lenses 64 arranged side by side on the light output side of the main body 63.

  The unit lenses 64 are arranged side by side on the light output side surface 63 </ b> A of the main body 63. As shown in FIG. 4, the unit lenses 64 extend linearly in the direction intersecting the arrangement direction AD of the unit lenses 64, particularly linearly in the present embodiment. In the present embodiment, a large number of unit lenses 64 included in one lens sheet 60, 65 extend in parallel with each other. Further, the longitudinal direction LD of the unit lenses 64 of the lens sheets 60 and 65 is orthogonal to the arrangement direction AD of the unit lenses 64 in the lens sheets 60 and 65.

  The unit lens 64 may have a triangular prism shape, a wavy shape, or a bowl shape such as a hemisphere. Specifically, examples of the unit lens include a unit prism, a unit cylindrical lens, and a unit microlens. Examples of the lens sheet having such a unit lens shape include a prism sheet, a lenticular lens sheet, and a microlens sheet. The unit lens 64 is a triangular prism unit prism whose width is narrowed toward the light output side.

  The unit lens 64 preferably has an apex angle of 80 ° or more and 100 ° or less, and more preferably an apex angle of about 90 °, from the viewpoint of improving the light utilization efficiency. However, the tip of the unit lens 64 may be a curved surface in consideration of breakage of the tip of the unit lens at the time of winding the light wavelength conversion sheet.

  As can be understood from FIG. 3, the arrangement direction of the unit lenses 64 of the lens sheet 60 and the arrangement direction of the unit lenses 64 of the lens sheet 65 intersect, more specifically, orthogonally.

<Reflection-type polarized light separation sheet>
The reflection-type polarization separation sheet 70 transmits only a first linearly polarized light component (for example, P-polarized light) out of the light emitted from the lens sheet 65 and is a second straight line orthogonal to the first linearly polarized light component. It has a function of reflecting a polarized light component (for example, S-polarized light) without absorbing it. In the state where the second linearly polarized light component reflected by the reflective polarization separation sheet 70 is reflected again and the polarized light is canceled (including both the first linearly polarized light component and the second linearly polarized light component), The light again enters the reflective polarization separation sheet 70. Therefore, the reflective polarization separating sheet 70 transmits the first linearly polarized light component of the incident light again, 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 emitted from the lens sheet 65 is emitted as the light source light that 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 70 coincide with the transmission axis direction of the polarizing plate 101 of the display panel 100, the emitted light from the backlight device 40 is obtained. All can be used for image formation on the display panel 100. Therefore, even when the light energy input from the light emitting device 10 is the same, it is possible to form an image with higher brightness than in the case where the reflective polarization separation sheet 70 is not arranged, and the energy utilization of the light emitting device 10 is possible. Efficiency is also improved.

  As the reflective polarization separating sheet 70, “DBEF” (registered trademark) available from 3M Company can be used. In addition to “DBEF”, a high-intensity polarizing sheet “WRPS” available from Shinwha Intertek, a wire grid polarizer, or the like can be used as the reflective polarization separating sheet 70.

<Reflection sheet>
The reflection sheet 80 has a function of reflecting the light leaking from the back surface 50 </ b> B of the optical plate 50 and making it enter the optical plate 50 again. The reflection sheet 80 includes a white scattering reflection sheet, a sheet made of a material having a high reflectance such as metal, a sheet containing a thin film (for example, a metal thin film) made of a material having a high reflectance as a surface layer, and the like. obtain. The reflection on the reflection sheet 80 may be regular reflection (specular reflection) or diffuse reflection. When the reflection on the reflection sheet 80 is diffuse reflection, the diffuse reflection may be isotropic diffuse reflection or anisotropic diffuse reflection.

<< Other backlight devices >>
The backlight device incorporating the light emitting device 10 may be a direct type backlight device as shown in FIG. The backlight device 110 shown in FIG. 5 includes a light emitting device 10, an optical plate 111 that receives light from the light emitting device 10 and functions as a light diffusing plate, and a lens sheet 60 disposed on the light output side of the optical plate 111. The lens sheet 65 disposed on the light exit side of the lens sheet 65 and the reflection type polarization separation sheet 70 disposed on the light exit side of the lens sheet 65 are provided. In the present embodiment, the light emitting device 10 is disposed not directly on the side of the optical plate 111 but directly below the optical plate 111. In FIG. 5, members denoted by the same reference numerals as those in FIG. 3 are the same as those shown in FIG. In the backlight device 110, the reflection sheet 80 is not provided.

  It is considered that the reason why the quantum dots are easily deteriorated by heat is as follows. First, as described above, a ligand composed of a sulfur compound, a phosphorus compound, or the like is coordinated on the surface of the quantum dot, and this ligand is easily detached by light or heat. When the ligand is detached from the quantum dot, moisture and oxygen are likely to adhere to the quantum dot, and the quantum dot is oxidized and deteriorated. Thereby, it is thought that a quantum dot will deteriorate with a heat | fever. On the other hand, in this embodiment, since the light wavelength conversion composition contains a silicone resin containing nitrogen atoms in addition to quantum dots, a nitrogen component can be present in the vicinity of the quantum dots. Thus, a light wavelength conversion composition having superior heat resistance can be obtained. This is because the nitrogen component present in the binder resin assists the role of the ligand even when the ligand is detached from the quantum dot (for example, the ligand binds to the quantum dot instead of the ligand, This is considered to be because the deterioration of the quantum dots is suppressed because at least one of the function of substituting for and the function of trapping oxygen is exhibited.

  In addition, since the silicone resin having at least one of the polyimide structure, the polyamide structure, and the polyamideimide structure has a nitrogen atom, the nitrogen atom is coordinated to the quantum dot, and the silicone resin having these structures is Since it is bulky, it has a function of suppressing the permeation of moisture and oxygen as compared with silicone resins that do not have these structures. That is, the specific silicone resin has a barrier property. Thereby, when the said specific silicone resin is used as a silicone resin containing a nitrogen atom, since permeation | transmission of a water | moisture content or oxygen can be suppressed, deterioration of a quantum dot can be suppressed more.

  In the above embodiment, the light wavelength conversion member 13 is incorporated in the light emitting device 10, but the arrangement position of the light wavelength conversion member is not particularly limited as long as the light wavelength conversion member 13 receives light from the light emitting device. For example, a light wavelength conversion sheet including a layered light wavelength conversion member may be incorporated at a position closer to the observer than the optical plate.

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

<Preparation of light wavelength conversion composition>
First, each component was mix | blended so that it might become a composition shown below, and the light wavelength conversion composition was obtained.
<Example 1>
(Light wavelength conversion composition 1)
Polyimide silicone resin (product name “SCR-1012”, manufactured by Shin-Etsu Chemical Co., Ltd.): 100 parts by mass Green emitting quantum dot (product name “CdSe / ZnS 530”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter of 3.3 nm): 0.2 parts by mass, red light emitting quantum dot (product name “CdSe / ZnS 610”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter of 5.2 nm) ): 0.2 parts by mass

<Example 2>
(Light wavelength conversion composition 2)
Polyimide silicone resin (product name “SCR-1016”, manufactured by Shin-Etsu Chemical Co., Ltd.): 100 parts by mass Green emitting quantum dot (product name “CdSe / ZnS 530”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter of 3.3 nm): 0.2 parts by mass, red light emitting quantum dot (product name “CdSe / ZnS 610”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter of 5.2 nm) ): 0.2 parts by mass

<Comparative Example 1>
(Light wavelength conversion composition 3)
Dimethyl silicone resin (product name “KER-2500”, manufactured by Shin-Etsu Chemical Co., Ltd.): 100 parts by mass Green emitting quantum dot (product name “CdSe / ZnS 530”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter of 3.3 nm): 0.2 parts by mass, red light emitting quantum dot (product name “CdSe / ZnS 610”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter of 5.2 nm) ): 0.2 parts by mass

<Comparative Example 2>
(Light wavelength conversion composition 4)
Phenyl silicone resin (product name “KER-6000”, manufactured by Shin-Etsu Chemical Co., Ltd.): 100 parts by mass Green emitting quantum dot (product name “CdSe / ZnS 530”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter of 3.3 nm): 0.2 parts by mass, red light emitting quantum dot (product name “CdSe / ZnS 610”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter of 5.2 nm) ): 0.2 parts by mass

<Example 3>
The light wavelength conversion composition 1 was filled in the opening (recessed part of the package body) of the reflecting member of a light emitting device (product name “B2020”, manufactured by Genelites) having a blue light emitting diode chip with an emission peak wavelength of 450 nm. Then, the light wavelength conversion composition is cured by heating at 100 ° C. for 5 hours, and the light emission according to Example 3 including the light wavelength conversion member filled in the opening of the reflection member and covering the blue light emitting diode. Got the device.

<Example 4>
In Example 4, a light emitting device was obtained in the same manner as in Example 3 except that the light wavelength conversion composition 2 was used instead of the light wavelength conversion composition 1.

<Comparative Example 3>
In Comparative Example 3, a light emitting device was obtained in the same manner as in Example 3 except that the light wavelength conversion composition 3 was used instead of the light wavelength conversion composition 1.

<Comparative example 4>
In Comparative Example 4, a light emitting device was obtained in the same manner as in Example 3 except that the light wavelength conversion composition 4 was used instead of the light wavelength conversion composition 1.

<Measurement of luminance maintenance rate after energization heat test>
In the light emitting devices according to the above-described examples and comparative examples, an energization heat resistance test was performed in which the power applied to the blue light emitting diode was energized to be 0.5 W and continuously lit for 500 hours in an environment at 80 ° C. The maintenance ratio of the luminance after the energization heat test with respect to the luminance before the energization heat test was examined. Specifically, first, a Kindle Fire (registered trademark) HDX7 backlight device was prepared. Then, by replacing the light emitting device of this backlight device with the light emitting device before the energization heat resistance test according to the example and the comparative example, the light emitting device was incorporated into the backlight device in the example and the comparative example.

  In the backlight device incorporating the light emitting device according to the example and the comparative example, the blue light emitting diode is turned on by energizing the blue light emitting diode so that the applied power to the blue light emitting diode is 0.5 W. The brightness of light emitted from the light emitting surface (the surface of the second prism sheet) is measured at a position 400 mm away from the light emitting surface (surface) of the backlight device in the thickness direction of the backlight device. CS2000 ”(manufactured by Konica Minolta Co., Ltd.) was used under the condition of a measurement angle of 1 °.

  Next, in this state, an energization heat resistance test was performed in which the blue light emitting diode was continuously lit for 500 hours in an environment of 80 ° C. And the brightness | luminance of the light radiate | emitted from the light emission surface (surface of a 2nd prism sheet) of a backlight apparatus after an energization heat resistance test is similar to the above, and the light emission surface of the backlight apparatus in the thickness direction of a backlight apparatus ( Measurement was performed at a measurement angle of 1 ° using a spectral radiance meter (product name “CS2000”, manufactured by Konica Minolta, Inc.) at a position 400 mm away from the surface.

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

The results are shown in Table 1.

  The results will be described below. As can be seen from Table 1, in the light emitting devices according to Examples 3 and 4, since a specific silicone resin was used, the heat resistance of the light emitting devices according to Comparative Examples 3 and 4 that did not use the specific silicone resin The luminance maintenance rate after the test was high.

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

DESCRIPTION OF SYMBOLS 10 ... Light-emitting device 12 ... Light-emitting element 13 ... Light wavelength conversion member 18 ... Quantum dot 19 ... Binder resin 30 ... Image display device 40 ... Backlight device 100 ... Display panel

Claims (10)

  An optical wavelength conversion composition comprising quantum dots and a silicone resin containing nitrogen atoms.   The light wavelength conversion composition according to claim 1, wherein the silicone resin has at least one of a polyimide structure, a polyamide structure, and a polyamideimide structure.   The light wavelength conversion member which consists of hardened | cured material of the light wavelength conversion composition of Claim 1. A light emitting element;
The light wavelength conversion member according to claim 3, which receives light from the light emitting element;
A light emitting device comprising:   The light emitting device according to claim 4, wherein the light emitting element is an LED element.   The light emitting device according to claim 4, wherein the light wavelength conversion member covers the light emitting element.   The light-emitting device according to claim 4, further comprising a sealing member provided between the light-emitting element and the light wavelength conversion member and sealing the light-emitting element.   The light emitting device according to claim 4, wherein a surface on the light output side of the light wavelength conversion member is a lens surface.   A backlight device comprising the light emitting device according to claim 4. The backlight device according to claim 9;
A display panel disposed on the light output side of the backlight device;
An image display device comprising:

Images