Dispersion, composition, sealing member, light-emitting device, lighting fixture, display device, and method for producing dispersion

Abstract

To provide a dispersion exhibiting superior storage stability even when no solvent is contained, a composition comprising the dispersion, a sealing member that is formed using the composition, a light-emitting device that includes the sealing member, a lighting fixture and a display device equipped with the light-emitting device, and a method for producing the dispersion.SOLUTION: A dispersion includes inorganic particles and a surface modification material, wherein at least a portion of the surface modification material is attached to the inorganic particles, the surface modification material includes a silane compound and a silicone compound, the content of the inorganic particles ranges from 1 mass% or more to 30 mass% or less, the viscosity is 100 Pa s or less, and the viscosity after being stored at 5°C for 30 days is 100 Pa s or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a dispersion, a composition, a sealing member, a light-emitting device, a lighting fixture, a display device, and a method for producing the dispersion. [Background technology]

[0002] Light-emitting diodes (LEDs) are widely used as light sources, offering advantages such as compact size, long life, and low-voltage operation. The LED chip in an LED package is generally encapsulated in a resin-containing encapsulant to prevent contact with external environmental degradation factors such as oxygen and moisture. Therefore, the light emitted from the LED chip passes through the encapsulant and is emitted toward the outside. Therefore, in order to increase the luminous flux emitted from the LED package, it is important to convert the wavelength of the light emitted from the LED chip using phosphor particles and then efficiently extract the white light outside the LED package.

[0003] To extend the lifespan of LEDs, there is a growing demand for methyl-based silicone resins with high heat resistance as encapsulating resins. Compared to conventionally commonly used phenyl silicone resins, methyl-based silicone resins have a higher methyl group content and a higher degree of hydrophobicity. Therefore, even when metal oxide particles with hydrophobic surfaces are mixed with methyl-based silicone resins, as in Patent Document 1, the metal oxide particles aggregate together, making it impossible to obtain a transparent composition. This problem becomes more pronounced as the content of metal oxide particles in the encapsulating material increases.

[0004] Patent Document 2 proposes a dispersion liquid for sealing light-emitting elements in which aggregation of metal oxide particles is suppressed even in a highly heat-resistant methyl-based silicone resin by surface modification with a high concentration of surface modification material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2016 / 142992 [Patent Document 2] International Publication No. 2020 / 203462 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the dispersions proposed in Patent Documents 1 and 2 thicken when the organic solvent contained in the dispersion is removed, and therefore require a step of removing the solvent immediately before or after mixing with the encapsulating resin, which is cumbersome.

[0007] The present invention has been made to solve the above-mentioned problems, and aims to provide a dispersion that has excellent storage stability even when it does not contain a solvent, a composition containing the dispersion, a sealing member formed using the composition, a light-emitting device having the sealing member, a lighting fixture and a display device including the light-emitting device, and a method for producing the dispersion. [Means for solving the problem]

[0008] The present invention has the following aspects. [1] A dispersion liquid comprising inorganic particles and a surface modification material, At least a portion of the surface modification material is attached to the inorganic particles, the surface modification material includes a silane compound and a silicone compound; The content of the inorganic particles is 1% by mass or more and 30% by mass or less, The viscosity is 100 Pa·s or less, A dispersion whose viscosity is 100 Pa·s or less after storage at 5°C for 30 days. [2] The dispersion according to [1], wherein the silane compound is an alkylalkoxysilane. [3] The dispersion according to [1] or [2], wherein the dispersion and a resin component are mixed in a mass ratio of 5:95, and the cured product has an in-line transmittance at a wavelength of 450 nm of 30% or more and 60% or less. [4] A composition comprising the dispersion according to any one of [1] to [3] and a resin component. [5] A sealing member which is a cured product of the composition according to [4]. [6] A light emitting device comprising the sealing member according to [5] and a light emitting element sealed by the sealing member. [7] A lighting fixture comprising the light-emitting device according to [6]. [8] A display device comprising the light-emitting device according to [6]. [9] A method for producing the dispersion liquid according to any one of [1] to [3], a first step of mixing a silane compound, a silicone compound, inorganic particles, and an organic solvent to obtain a mixed solution; a second step of dispersing the inorganic particles in the mixed liquid to obtain a first dispersion; a third step of mixing the first dispersion with a silicone compound to obtain a second dispersion; a fourth step of removing the organic solvent from the second dispersion to obtain a third dispersion, In the first step, the content of the inorganic particles in the mixed solution is 10% by mass or more and 49% by mass or less, In the first step, the content of the organic solvent in the mixed solution is 1% by mass or more and 50% by mass or less, The method for producing a dispersion, wherein in the first step, the total content of the silane compound, the silicone compound, and the inorganic particles in the mixed liquid is 50% by mass or more and 99% by mass or less.

[10] The method for producing a dispersion liquid according to [9], wherein the inorganic particles are dry-treated with a silicone compound. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a dispersion that has excellent storage stability even when it does not contain a solvent, a composition containing the dispersion, a sealing member formed using the composition, a light-emitting device having the sealing member, a lighting fixture and a display device including the light-emitting device, and a method for producing the dispersion. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram illustrating an example of a light-emitting device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE INVENTION Embodiments of the dispersion, composition, sealing member, light-emitting device, lighting fixture and display device, and method for producing the dispersion of the present invention will be described. It should be noted that the present embodiment is specifically described to allow a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

[0012] <1.Dispersion> The dispersion according to this embodiment contains inorganic particles and a surface modification material, and at least a portion of the surface modification material is attached to the inorganic particles. The dispersion according to this embodiment is a liquid in which a surface-modifying material is attached to inorganic particles, and does not contain a solvent such as water or an organic solvent for dispersing the inorganic particles. The dispersion according to this embodiment is made of inorganic particles in a surface-modified state, but has different properties from a dry powder and is in a liquid state, so for convenience, the term "dispersion" is used. The dispersion according to this embodiment is mixed with a resin component that will form the matrix of the sealing member, as described below, and the mixture is cured to be used as a sealing member for light-emitting elements. That is, the dispersion according to this embodiment does not contain the resin component described below to an extent that it can be used to form a sealing member even when simply cured. More specifically, the mass ratio of the resin component to the dispersion in this embodiment, resin component:dispersion, is preferably in the range of 0:100 to 40:60, and more preferably in the range of 0:100 to 20:80. The composition according to this embodiment is more preferably essentially free of the resin component described below, and particularly preferably completely free of the resin component described below.

[0013] The viscosity of the dispersion of this embodiment is 100 Pa s or less, preferably 50 Pa s or less, more preferably 10 Pa s or less, even more preferably 5 Pa s or less, and even more preferably 1 Pa s or less. If the viscosity exceeds the upper limit, it becomes difficult to mix the dispersion with the sealing resin described below.

[0014] The dispersion of this embodiment has a viscosity of 100 Pa s or less, preferably 50 Pa s or less, more preferably 10 Pa s or less, even more preferably 5 Pa s or less, and even more preferably 1 Pa s or less, after storage at 5° C. for 30 days. If the viscosity exceeds the upper limit, the storage stability of the dispersion will be poor, and the quality stability of the composition, sealing member, etc., described below, will be poor. The dispersion of this embodiment preferably exhibits a small rate of change in viscosity after storage at 5°C for 30 days from the date of manufacture. For example, the rate of change in viscosity ((viscosity after 30 days - viscosity on the day of manufacture) / viscosity on the day of manufacture) is preferably within 300%, more preferably within 200%, even more preferably within 100%, even more preferably within 50%, and most preferably 0%. By keeping the rate of change in viscosity within the above range, changes in the properties of the dispersion of this embodiment are suppressed from occurring between the time of its production and the time of its mixing with the resin component, and the composition can be produced under the same conditions for a certain period of time. The dispersion of this embodiment contains a solvent during the production process, but has good storage stability even when the solvent is removed, allowing a large amount of dispersion to be produced at once and then stored and used.

[0015] The viscosity of the composition of the present embodiment can be measured in accordance with JIS Z 8803:2011, for example, using a rheometer (product name: Rheostress RS-6000, manufactured by HAAKE) at 25°C and a shear rate of 1 (1 / s).

[0016] (1.1 inorganic particles) The inorganic particles scatter the light emitted from the light emitting element in the sealing member described below. In addition, depending on the type of inorganic particles, the inorganic particles can improve the refractive index of the sealing member. As a result, the inorganic particles contribute to improving the brightness of the light emitted by the light emitting device.

[0017] The inorganic particles are not particularly limited. Examples of the inorganic particles include zirconium oxide particles, aluminum oxide particles, titanium oxide particles, silica particles, zinc oxide particles, iron oxide particles, copper oxide particles, tin oxide particles, cerium oxide particles, tantalum oxide particles, niobium oxide particles, tungsten oxide particles, europium oxide particles, yttrium oxide particles, molybdenum oxide particles, indium oxide particles, antimony oxide particles, germanium oxide particles, lead oxide particles, bismuth oxide particles, hafnium oxide particles, potassium titanate particles, barium titanate particles, strontium titanate particles, potassium niobate particles, lithium niobate particles, calcium tungstate particles, At least one selected from the group consisting of aluminum particles, yttria-stabilized zirconia particles, alumina-stabilized zirconia particles, silica-stabilized zirconia particles, calcia-stabilized zirconia particles, magnesia-stabilized zirconia particles, scandia-stabilized zirconia particles, hafnia-stabilized zirconia particles, ytterbia-stabilized zirconia particles, ceria-stabilized zirconia particles, indium-stabilized zirconia particles, strontium-stabilized zirconia particles, samarium oxide-stabilized zirconia particles, gadolinium oxide-stabilized zirconia particles, antimony-doped tin oxide particles, and indium-doped tin oxide particles is preferably used.

[0018] Among the above, from the viewpoint of improving transparency and compatibility (affinity) with the encapsulating resin (resin component), the inorganic particles are preferably at least one type selected from the group consisting of zirconium oxide particles, aluminum oxide particles, titanium oxide particles, and silica particles.

[0019] In order to improve the refractive index of the sealing member, the inorganic particles preferably have a refractive index of 1.7 or more. Examples of such inorganic particles include inorganic particles other than the silica particles described above. In order to suppress excessive scattering of light, the inorganic particles preferably have a refractive index of 2.5 or less.

[0020] The inorganic particles are more preferably at least one of zirconium oxide particles and aluminum oxide particles, and particularly preferably zirconium oxide particles.

[0021] The inorganic particles may be dispersed in the dispersion liquid as primary particles or as secondary particles formed by aggregation of primary particles. Usually, inorganic particles are dispersed as secondary particles.

[0022] The average dispersed particle diameter of the inorganic particles in the dispersion liquid is not particularly limited as long as the dispersed particle diameter (aggregated particle diameter) in the sealing member is 60 nm to 1000 nm. The average dispersed particle diameter of the inorganic particles may be, for example, 10 nm to 1000 nm, 50 nm to 800 nm, or 60 nm to 700 nm. By setting the average dispersed particle diameter of the inorganic particles to 10 nm or more, the brightness of the light emitted from the light-emitting device (described later) manufactured using this dispersion is improved. Furthermore, by setting the average dispersed particle diameter of the inorganic particles to 1000 nm or less, the decrease in the light transmittance of the dispersion, composition, and sealing member can be suppressed. As a result, the brightness of the light emitted from the light-emitting device is improved.

[0023] The average dispersed particle diameter of the inorganic particles in this embodiment can be measured, for example, by observation using a transmission electron microscope. First, a collodion film on which inorganic particles have been collected from a dispersion is observed using a transmission electron microscope to obtain a transmission electron microscope image. Next, a predetermined number of inorganic particles, for example, 100 particles, are selected from the transmission electron microscope image. The longest straight line segment (maximum major axis) of each of these inorganic particles is then measured, and the average diameter is calculated by arithmetically averaging these measurements. However, since it is difficult to observe all inorganic particles in a dispersion, it is difficult to uniquely define the average dispersed particle size of inorganic particles in a dispersion. Furthermore, even if the average dispersed particle size is approximately the same, the light transmittance will differ if the degree of aggregation of particles differs. Therefore, it is difficult to accurately measure the average dispersed particle size of inorganic particles in a dispersion. Therefore, it is difficult to identify the characteristics of the dispersion of this embodiment based on the average dispersed particle size of inorganic particles. The characteristics of the dispersion of this embodiment may be determined by measuring properties such as brightness and chromaticity.

[0024] In the dispersion of the present embodiment, when observed with the above-mentioned transmission electron microscope, the maximum aggregate particle size of the inorganic particles is preferably 1000 nm or less, more preferably 700 nm or less, even more preferably 500 nm or less, and even more preferably 300 nm or less. When the maximum aggregate particle size is within the above range, the dispersion liquid has excellent storage stability and transparency, which is preferable. It should be noted that since the dispersion liquid of this embodiment does not contain a solvent such as water or an organic solvent, it is difficult to measure the average particle size using a particle size distribution analyzer.

[0025] Furthermore, the average dispersed particle diameter of inorganic particles is measured and calculated based on the diameter of the inorganic particles in a dispersed state, regardless of whether the inorganic particles are dispersed as primary particles or secondary particles. Furthermore, in this embodiment, the average dispersed particle diameter of inorganic particles may be measured as the average dispersed particle diameter of inorganic particles to which a surface modification material is attached. Since inorganic particles to which a surface modification material is attached and inorganic particles to which no surface modification material is attached may exist in a dispersion liquid, the average dispersed particle diameter of inorganic particles is usually measured as a value in a mixed state of these.

[0026] In the dispersion of this embodiment, when the content of inorganic particles is 20% by mass, the linear transmittance at a wavelength of 600 nm is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more. By ensuring that the linear transmittance of the dispersion is within the above range, it is possible to suppress a decrease in the light transmittance of the dispersion, composition, and sealing member. As a result, the brightness of the light emitted from the light-emitting device is improved. The upper limit of the linear transmittance of the dispersion of this embodiment is not particularly limited, and may be 90% or less, 80% or less, or 70% or less.

[0027] The average primary particle diameter of the inorganic particles is, for example, preferably 3 nm or more and 100 nm or less, more preferably 4 nm or more and 80 nm or less, and even more preferably 10 nm or more and 60 nm or less. By having the average primary particle diameter of the inorganic particles within the above range, it is possible to suppress a decrease in the transparency of the sealing member. As a result, it is possible to further improve the brightness of the light emitted from the light emitting device.

[0028] The average primary particle diameter of inorganic particles can be measured, for example, by observation using a transmission electron microscope. First, a collodion film on which inorganic particles have been collected from a dispersion is observed using a transmission electron microscope to obtain a transmission electron microscope image. Next, a predetermined number of inorganic particles, for example, 100 particles, are selected from the transmission electron microscope image. The longest straight line segment (maximum major axis) of each of these inorganic particles is then measured, and the average diameter is calculated by arithmetically averaging these measured values. The dispersion used to measure the primary particle diameter of inorganic particles may be the dispersion of this embodiment, or a dispersion in which inorganic particles before surface modification are dispersed in water, alcohol, or the like may be used.

[0029] Here, when inorganic particles are aggregated together, the aggregate particle size of the aggregate is not measured, but the maximum major axis of a predetermined number (e.g., 100 particles) of inorganic particles (primary particles) constituting the aggregate is measured and used as the average primary particle size.

[0030] The content of inorganic particles in the dispersion of this embodiment is preferably 1% by mass or more and 30% by mass or less. The content of inorganic particles may be 5% by mass or more and 25% by mass or less, or may be 10% by mass or more and 20% by mass or less. If the content of inorganic particles is less than the lower limit, the amount of surface modification material in the dispersion will be relatively large. When the dispersion is made into an LED package (light-emitting device), the light emitted from the light-emitting element will not be sufficiently scattered, and the brightness of the LED package will not be improved. If the content of inorganic particles exceeds the upper limit, the amount of surface modification material in the dispersion will be relatively small. When the dispersion of this embodiment is mixed with a resin component described below, aggregation of the inorganic particles will not be sufficiently suppressed, the dispersion will thicken, and the transparency will decrease.

[0031] At least a portion of the surface modifying material described below is attached to the surface of the inorganic particles, which allows the inorganic particles to be stably dispersed in the dispersion liquid even in the absence of a solvent.

[0032] (1.2 Surface modification materials) The surface modification material of this embodiment contains a silane compound and a silicone compound. The silane compound adheres to the surface of the inorganic particles and contributes to making the surface of the inorganic particles hydrophobic. The silicone compound adheres to the surface of the inorganic particles and contributes to improving compatibility with the resin component described below. The ratio of the silane compound to the silicone compound may be appropriately selected depending on the properties of the resin component used. From the viewpoint of improving the storage stability of the dispersion, a larger amount of the silicone compound is preferred. On the other hand, when the resin component is highly hydrophobic, a larger amount of the silane compound is preferred in order to improve the transparency of the sealing member described below.

[0033] The mass ratio of the silane compound to the silicone compound may be adjusted appropriately depending on the resin components used, and may be, for example, 1:1 to 1:50, 1:1 to 1:40, 1:1 to 1:30, or 1:1 to 1:20. The silane compound is preferably 10 parts by mass or more and 49 parts by mass or less, or may be 15 parts by mass or more and 45 parts by mass or less, or may be 20 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass of the inorganic particles. The amount of the silicone compound is preferably 300 parts by mass or more and 800 parts by mass or less, and may be 500 parts by mass or more and 700 parts by mass or less, relative to 100 parts by mass of the inorganic particles. When the mass ratio of the silane compound to the silicone compound is within the above range, a dispersion having excellent storage stability can be obtained even in the absence of a solvent in the dispersion.

[0034] Here, the expression "adhering" the surface modification material to the inorganic particles means that the surface modification material comes into contact with or bonds to the inorganic particles through an interaction or reaction between them. Examples of contact include physical adsorption. Examples of bonding include ionic bonding, hydrogen bonding, and covalent bonding.

[0035] Such a surface modification material is not particularly limited as long as it can be attached to inorganic particles, has good compatibility with the resin component described below, and can suppress aggregation of inorganic particles in the dispersion even in the absence of a solvent, thereby suppressing an increase in the viscosity of the dispersion. As such a silane compound, a silane compound having a reactive functional group, for example, at least one functional group selected from the group consisting of an alkenyl group, an H—Si group, and an alkoxy group, is preferably used. In particular, a surface modification material having an alkoxy group is preferably used in this embodiment because it can react with water and be hydrolyzed.

[0036] The alkenyl group may be, for example, a straight-chain or branched alkenyl group having 2 to 5 carbon atoms, and specific examples thereof include a vinyl group, a 2-propenyl group, and a prop-2-en-1-yl group. Examples of the alkoxy group include linear or branched alkoxy groups having 1 to 5 carbon atoms, and specific examples include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, and a butoxy group.

[0037] Examples of such silane compounds include methyltriethoxysilane, vinyltrimethoxysilane, isobutyltrimethoxysilane, phenyltrimethoxysilane, methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, dimethylchlorosilane, methyldichlorosilane, diethylchlorosilane, ethyldichlorosilane, methylphenylchlorosilane, diphenylchlorosilane, phenyldichlorosilane, trimethoxysilane, dimethoxysilane, monomethoxysilane, triethoxysilane, diethoxymonomethylsilane, monoethoxydimethylsilane, methylphenyldimethoxysilane, diphenylmonomethoxysilane, methylphenyldiethoxysilane, and diphenylmonoethoxysilane. Among these, alkylalkoxysilanes such as methyltriethoxysilane, propyltriethoxysilane, and octyltriethoxysilane are preferred.

[0038] The silicone compound of the present embodiment is not particularly limited as long as it is compatible with the resin component described below. The silicone compound of the present embodiment may be selected from those having a structure with the same or closer functional group ratio to that of the resin component used. The silicone compound of the present embodiment may be a monomer, an oligomer, or a polymer. From the viewpoints of ease of handling and compatibility with the resin component, it is preferable to use an oligomer. Examples of silicone compounds include methyl hydrogen silicone, methyl phenyl hydrogen silicone, diphenyl hydrogen silicone, phenyl silicone having alkoxy at both ends, methyl phenyl silicone, methyl phenyl silicone having alkoxy at both ends, methyl phenyl silicone having alkoxy at both ends, methyl phenyl silicone having an alkoxy group, dimethyl silicone having an alkoxy group, dimethyl silicone having an alkoxy group at one end and trimethyl at one end (methyl group at one end), and phenyl silicone having an alkoxy group. The silicone compound may be an oligomer or a resin (polymer).

[0039] The content of the surface modification material in the dispersion of this embodiment is preferably 70% by mass or more and 99% by mass or less, more preferably 75% by mass or more and 95% by mass or less, and even more preferably 80% by mass or more and 90% by mass or less. If the content of the surface modification material is less than the lower limit, when the dispersion of this embodiment is mixed with a resin component described below, aggregation of the inorganic particles is not sufficiently suppressed, the dispersion increases in viscosity, and the transparency also decreases, which is not preferable. If the content of the surface modification material exceeds the upper limit, the content of the inorganic particles becomes relatively small, and when the LED package is formed, the light emitted from the light-emitting element cannot be sufficiently scattered, and the brightness of the LED package cannot be improved, which is undesirable.

[0040] The dispersion of this embodiment and a resin component are mixed in a mass ratio of 5:95, and the cured product has a linear transmittance at a wavelength of 600 nm of preferably 30% to 80% or less, more preferably 35% to 75% or less, and even more preferably 40% to 70% or less. Also, the linear transmittance at a wavelength of 450 nm is preferably 5% to 70% or less, and even more preferably 10% to 15%. It is more preferable that the ratio is from 15% to 60% and even more preferable that the ratio is from 15% to 55%. When the linear transmittance is within the above range, the decrease in the light transmittance of the sealing member can be suppressed, and as a result, the brightness of the light from the light emitting device is improved.

[0041] The linear transmittance can be measured, for example, using a spectrophotometer (manufactured by JASCO Corporation, model number: V-770).

[0042] The resin component will be described later. The dispersion of the present embodiment may contain surface modifying materials other than the silane compound and the silicone compound, and general additives, as long as the purpose and effects of the present invention are not impaired.

[0043] The dispersion according to this embodiment has excellent storage stability because aggregation of inorganic particles is suppressed in the dispersion despite the absence of a solvent. In other words, the dispersion is easy to handle and can be stored for a long period of time. Furthermore, in a sealing member prepared using the dispersion according to this embodiment, the refractive index improvement effect of the inorganic particles and the scattering effect of light emitted from the light-emitting element can be fully exhibited while suppressing a decrease in light transmittance due to aggregation of the inorganic particles. As a result, the brightness of light from a light-emitting device including a light-emitting element sealed with a composition prepared using the dispersion according to this embodiment is improved.

[0044] <2. Dispersion Method> The method for producing a dispersion liquid according to this embodiment includes a first step of mixing a silane compound, a silicone compound, inorganic particles, and an organic solvent to obtain a mixed liquid, a second step of dispersing the inorganic particles in the mixed liquid to obtain a first dispersion liquid, a third step of mixing the first dispersion liquid with a silicone compound to obtain a second dispersion liquid, and a fourth step of removing the organic solvent from the second dispersion liquid to obtain a third dispersion liquid, wherein in the first step, the content of the inorganic particles in the mixed liquid is 10% by mass or more and 49% by mass or less, the content of the organic solvent is 1% by mass or more and 50% by mass or less, and the total content of the silane compound, the silicone compound, and the inorganic particles is 50% by mass or more and 99% by mass or less.

[0045] (2.1 First step) In the first step, a silane compound, a silicone compound, inorganic particles, and an organic solvent are mixed to obtain a mixed solution. In the first step, the content of the inorganic particles in the mixed solution is 10% by mass or more and 49% by mass or less, the content of the organic solvent is 1% by mass or more and 50% by mass or less, and the total content of the silane compound, the silicone compound, and the inorganic particles is 50% by mass or more and 99% by mass or less. This allows for an increase in the amount of silicone compound attached, which was previously difficult, while also allowing the surfaces of the inorganic particles to be densely modified with a surface modification material.

[0046] (Hydrolysis process) The silane compound and silicone compound may be those which have been subjected to a hydrolysis reaction. Although a silane compound will be described as an example, a silicone compound can also be hydrolyzed in the same manner. In the hydrolysis step, at least the silane compound is mixed with water to obtain a hydrolysis solution containing the hydrolyzed silane compound. By using such a mixed solution in which at least a portion of the silane compound has been hydrolyzed in advance, the silane compound can be easily attached to the inorganic particles in the dispersion step described below.

[0047] As the silane compound, one of the above-mentioned silane compounds may be used alone, or two or more of them may be used in combination. The content of the silane compound in the hydrolyzed liquid is not particularly limited. It can be the remainder after removing other components from the hydrolyzed liquid, but for example, it is preferably 60% by mass to 99% by mass, more preferably 70% by mass to 97% by mass, and even more preferably 80% by mass to 95% by mass. The content of the silane compound in the hydrolyzed liquid may be 85% by mass to 95% by mass, or 87% by mass to 93% by mass, as necessary. When two or more silane compounds are used in combination, each may be hydrolyzed independently, or two or more silane compounds may be hydrolyzed in a mixed state.

[0048] In the hydrolysis step, a surface modifying material other than the silane compound may be contained in the hydrolysis solution.

[0049] In the hydrolysis step, the hydrolysis solution contains water, which serves as a substrate for the hydrolysis reaction of the surface modification material such as a silane compound. The content of water in the hydrolysis solution is not particularly limited and can be selected arbitrarily. For example, the content of water can be appropriately set according to the amount of the silane compound. For example, the amount of water added to the hydrolysis solution is preferably 0.5 mol to 5 mol, more preferably 0.6 mol to 3 mol, and even more preferably 0.7 mol to 2 mol, per mol of the silane compound. This allows the hydrolysis reaction of the silane compound to proceed sufficiently, while more reliably preventing aggregation of inorganic particles in a dispersion produced with an excess amount of water.

[0050] Alternatively, the water content in the hydrolyzed liquid is, for example, preferably 1% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and even more preferably 1% by mass or more and 10% by mass or less.

[0051] A catalyst may be added to the hydrolysis solution together with the silane compound and water. The catalyst may be, for example, an acid or a base. The acid catalyzes the hydrolysis reaction of the silane compound in the hydrolysis solution. Meanwhile, the base catalyzes the condensation reaction of the hydrolyzed silane compound with functional groups, such as hydroxyl groups and silanol groups, on the surface of the metal oxide particles. These reactions facilitate the adhesion of the silane compound to the inorganic particles in the second step, improving the dispersion stability of the inorganic particles. As the catalyst, an acid is preferably used. From the viewpoint of acidity, the acid is preferably an inorganic acid, and more preferably hydrochloric acid.

[0052] The catalyst content in the hydrolysis solution is not particularly limited, but is preferably 10 ppm to 1000 ppm, more preferably 20 ppm to 800 ppm, and even more preferably 30 ppm to 600 ppm. This allows for sufficient promotion of hydrolysis of the silane compound while suppressing side reactions of the silane compound. If necessary, the catalyst content in the hydrolysis solution may be 0.1 ppm to 100 ppm, or 1 ppm to 10 ppm. For example, when an acid such as hydrochloric acid (1N) is used as a catalyst, the amount of the acid may be 0.001 parts by mass to 5 parts by mass, 0.001 parts by mass to 3 parts by mass, 0.005 parts by mass to 1 part by mass, or 0.005 parts by mass to 0.1 parts by mass, per 100 parts by mass of the hydrolysis solution.

[0053] The hydrolysis solution may also contain a hydrophilic solvent, if necessary, which promotes miscibility of the silane compound with water in the hydrolysis solution and further accelerates the hydrolysis reaction of the silane compound.

[0054] Examples of such hydrophilic solvents include alcohol solvents, ketone solvents, and nitrile solvents. These hydrophilic solvents may be used alone or in combination of two or more. The content of the hydrophilic solvent in the hydrolysis solution may be 0% by mass or more and 85% by mass or less, or 10% by mass or more and 70% by mass or less.

[0055] Among the above, from the viewpoint of having excellent affinity with water and the hydrophobic solvent and promoting miscibility thereof, the hydrophilic solvent preferably includes at least one selected from the group consisting of alcohol-based solvents, and more preferably includes at least one selected from the group consisting of methanol and ethanol.

[0056] The content of the hydrophilic solvent in the hydrolyzed liquid is not particularly limited, but is preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less, for example. Within this range, the contents of the silane compound and water in the hydrolyzed liquid can be sufficiently increased. The content of the hydrophilic solvent in the hydrolysis solution may be 40% by mass or less, or 20% by mass or less. The content of the hydrophilic solvent in the hydrolysis solution is preferably, for example, 10% by mass or more, and more preferably 15% by mass or more. This range further promotes miscibility of the silane compound with water, thereby allowing the hydrolysis reaction of the silane compound to proceed efficiently. The hydrolysis solution does not necessarily contain any hydrophilic solvent other than the compound derived from the hydrolysis reaction. In other words, the hydrophilic solvent may contain only the compound derived from the hydrolysis reaction.

[0057] In this embodiment, when a silane compound having an alkoxy group is used as the silane compound, the silane compound undergoes hydrolysis, resulting in the inclusion of an alcohol compound derived from the alkoxy group in the mixed solution. The hydrolysis reaction also proceeds with the water adsorbed on the inorganic particles, so it can occur in any of the first to third steps. Therefore, in this case, unless a step for removing the alcohol compound is included, the resulting dispersion will contain the alcohol compound. Therefore, a step for removing these alcohol compounds using an evaporator or the like may be provided as appropriate.

[0058] In the hydrolysis step, after the hydrolysis solution is prepared, it may be kept at a constant temperature selected arbitrarily for a predetermined time, thereby further promoting the hydrolysis of the silane compound. In this treatment, the temperature of the hydrolysis solution is not particularly limited and can be selected arbitrarily and can be changed appropriately depending on the type of silane compound. For example, it is preferably 5°C or higher and 65°C or lower, more preferably 20°C or higher and 65°C or lower, and even more preferably 30°C or higher and 60°C or lower. If necessary, it may be 40°C or higher and 75°C or lower, or 50°C or higher and 70°C or lower.

[0059] The holding time at the above temperature is not particularly limited, but is preferably 10 to 180 minutes, more preferably 30 to 120 minutes, and may be 15 to 60 minutes, or 20 to 40 minutes, as needed. During the above-mentioned retention of the hydrolyzed liquid, the hydrolyzed liquid may be appropriately stirred.

[0060] The inorganic particles, silane compounds, and silicone compounds to be mixed into the mixture may be the same as those listed as the constituents of the dispersion liquid. From the viewpoint of suppressing aggregation of inorganic particles in the dispersion, the inorganic particles are preferably dry-treated with a silicone compound.

[0061] (Dry treatment process of inorganic particles with silicone compounds) The method for dry-treating inorganic particles with a silicone compound is not particularly limited as long as the silicone compound adheres to the surfaces of the inorganic particles, and examples thereof include a method in which inorganic particles and a silicone compound are mixed in a general device such as a known stirrer or disperser, followed by heat treatment. During the mixing, water, a catalyst, an alcohol such as methanol, ethanol, or isopropanol, or an organic solvent such as n-hexane, toluene, or xylene may be added. The content of the organic solvent is preferably 0% by mass or more and 40% by mass or less, and may be 5% by mass or more and 35% by mass or less, or 10% by mass or more and 30% by mass or less, based on the total amount of the inorganic particles, the silicone compound, and the organic solvent. The heat treatment temperature is preferably 70°C or higher and 200°C or lower, and may be 90°C or higher and 180°C or lower, or 100°C or higher and 160°C or lower. The amount of the silicone compound mixed with respect to 100 parts by mass of the inorganic particles is preferably 1 part by mass or more and 20 parts by mass or less, and may be 3 parts by mass or more and 10 parts by mass or less. By dry-adhering a silicone compound to the surface of inorganic particles, aggregation of inorganic particles in a dispersion can be further suppressed. By using inorganic particles whose surfaces have been pre-modified with such a silicone compound, the maximum aggregate particle size can be kept to 300 nm or less even in a cured product of a mixture mixed with a resin component.

[0062] In the first step, the organic solvent to be mixed into the mixed solution is not particularly limited as long as it can be mixed with the inorganic particles, the silane compound, and the silicone compound. Examples of such solvents include alcohols such as methanol, ethanol, and isopropanol, as well as n-hexane, toluene, and xylene. Hydrophobic solvents are preferred from the viewpoint of ease of mixing with the silicone compound.

[0063] Examples of hydrophobic solvents include aromatics, saturated hydrocarbons, and unsaturated hydrocarbons. These solvents may be used alone or in combination of two or more. Among the above, aromatics, particularly aromatic hydrocarbons, are preferred because they are easily mixed with silicone compounds.

[0064] Examples of such aromatic hydrocarbons include benzene, toluene, ethylbenzene, 1-phenylpropane, isopropylbenzene, n-butylbenzene, tert-butylbenzene, sec-butylbenzene, o-xylene, m-xylene, p-xylene, 2-ethyltoluene, 3-ethyltoluene, 4-ethyltoluene, etc. These aromatic hydrocarbons may be used alone or in combination of two or more.

[0065] Among the above, from the viewpoints of the stability of the mixed liquid and ease of handling in removing the organic solvent, etc., it is particularly preferable to use at least one dispersion medium selected from the group consisting of toluene, o-xylene, m-xylene, p-xylene, and benzene.

[0066] The content of inorganic particles in the mixed solution is 10% by mass or more and 49% by mass or less, preferably 10% by mass or more and 40% by mass or less, and more preferably 10% by mass or more and 30% by mass or less. If the content of inorganic particles is less than the lower limit, a dispersion that can improve the brightness of the LED package cannot be obtained. If the content of inorganic particles exceeds the upper limit, the content of surface modification material becomes relatively small, and a dispersion that is excellent in storage stability cannot be obtained.

[0067] The content of the surface modification material in the mixed solution is not particularly limited, but is preferably, for example, 60% by mass to 95% by mass, and more preferably 70% by mass to 90% by mass. If the content of the surface modification material is above the lower limit, a dispersion with excellent storage stability cannot be obtained. If the content of the surface modification material is below the upper limit, a dispersion that can improve the brightness of the LED package cannot be obtained.

[0068] The total content of the silane compound, silicone compound, and inorganic particles in the mixed solution is 50% by mass or more and 99% by mass or less, preferably 55% by mass or more and 90% by mass or less, and more preferably 60% by mass or more and 80% by mass or less. If the total content is less than the lower limit, the content of the organic solvent will be relatively high, the inorganic particles will not be sufficiently hydrophobicized by the surface modification material, and aggregation of the inorganic particles in the dispersion will not be suppressed. If the total content exceeds the upper limit, the content of the organic solvent will be relatively low, and surface modification with the silicone compound may not be sufficient.

[0069] The content of the organic solvent in the mixed solution is 1% by mass or more and 50% by mass or less, preferably 10% by mass or more and 45% by mass or less, and more preferably 15% by mass or more and 40% by mass or less. If the content of the organic solvent is less than the lower limit, the surface modification of the silicone compound may not be sufficient. If the content of the organic solvent exceeds the upper limit, the inorganic particles are not sufficiently hydrophobicized by the surface modification material, and aggregation of the inorganic particles in the dispersion is not suppressed.

[0070] After the mixture is prepared, it may be kept at a constant temperature for a predetermined period of time, which can further promote the hydrolysis of the surface modification material. In this treatment, the temperature of the mixed solution is not particularly limited and can be changed appropriately depending on the type of surface modification material, but is preferably 5°C or higher and 65°C or lower, and more preferably 30°C or higher and 60°C or lower.

[0071] The retention time is not particularly limited, but is preferably, for example, 10 minutes or more and 180 minutes or less, and more preferably 30 minutes or more and 120 minutes or less. In addition, the mixed liquid may be appropriately stirred during the above-mentioned holding of the mixed liquid.

[0072] (2.2 Second step) Next, inorganic particles are dispersed in the mixed liquid to obtain a first dispersion liquid.

[0073] The first dispersion can be prepared, for example, by mixing the components of the first dispersion and then dispersing the mixture using a known dispersing machine.

[0074] Suitable known dispersing machines include, for example, a bead mill, a ball mill, a homogenizer, a disperser, a stirrer, etc. In the dispersing step, it is preferable to disperse the inorganic particles in the mixed liquid by applying the minimum necessary energy without applying excessive energy so that the particle diameters of the inorganic particles in the dispersion liquid (dispersed particle diameters) become approximately uniform. The dispersion time can be selected arbitrarily depending on the conditions, but may be, for example, 3 to 20 hours, preferably 4 to 18 hours, more preferably 6 to 16 hours, and even more preferably 8 to 14 hours, but is not limited to these. The dispersion temperature can be selected arbitrarily, and may be, for example, 10° C. to 50° C., preferably 20° C. to 40° C., and more preferably 30° C. to 40° C. However, the dispersion temperature is not limited to these. The second step differs from the first step in that dispersion is carried out continuously over a certain period of time.

[0075] (2.3 Third step) Next, the first dispersion liquid is mixed with a silicone compound to obtain a second dispersion liquid, in which a sufficient amount of the silicone compound is attached to the surfaces of the inorganic particles.

[0076] As the silicone compound to be mixed into the first dispersion, those listed as constituent components of the dispersion described above can be used.

[0077] The content of the silicone compound in the second dispersion is not particularly limited, but is preferably 400 to 800 parts by mass, and more preferably 500 to 700 parts by mass, per 100 parts by mass of inorganic particles, in total with the silicone compound mixed in the dry treatment or the first step. When the content of the silicone compound is equal to or greater than the lower limit, a dispersion having excellent storage stability can be obtained. When the content of the silicone compound is equal to or less than the upper limit, the brightness of the light-emitting device can be improved.

[0078] The second dispersion can be produced, for example, by mixing the first dispersion with the silicone compound, and then mixing them in a known disperser while controlling the power of the disperser.

[0079] Suitable known dispersing machines include, for example, a bead mill, a ball mill, a homogenizer, a disperser, and a stirrer.

[0080] (2.4 Fourth step) Next, the organic solvent is removed from the second dispersion to obtain the dispersion of this embodiment.

[0081] The method for removing the organic solvent from the second dispersion is not particularly limited, but for example, an evaporator can be used. It is preferable to completely remove the organic solvent, but it may remain in an amount of about 5 mass % or less, as long as it does not affect the properties of the sealing member and the light-emitting device described below.

[0082] The dispersion according to the present embodiment can be obtained by the above method. It is presumed that the dispersion obtained in the above manner has a larger amount of silicone compound attached to the surface of the inorganic particles than conventional dispersions, and has excellent storage stability, contributing to improved brightness of light-emitting devices. Conventionally, in order to mix inorganic particles with a highly hydrophobic methyl-based silicone resin, it was thought necessary to surface-modify the inorganic particles in a high concentration of silane compound. Therefore, it was difficult to increase the content ratio of silicone compound as a surface modification material for inorganic particles. However, the present manufacturing method can increase the amount of silicone compound attached to the surface of the inorganic particles.

[0083] <3. Composition> The composition according to this embodiment includes the dispersion according to this embodiment and a resin component. The composition according to this embodiment is cured as described below and used as a sealing member for a light-emitting device. The composition according to this embodiment includes inorganic particles that contribute to improving the refractive index and transparency described above, and therefore, when used as a sealing member, the brightness of light emitted from a light-emitting device can be improved.

[0084] The content of inorganic particles in the composition of this embodiment is preferably 0.01% by mass to 10% by mass, more preferably 0.1% by mass to 5% by mass, and even more preferably 0.2% by mass to 3% by mass. If the content of the composition is less than the lower limit, the content of inorganic particles may be insufficient, making it impossible to improve the brightness of the light-emitting device. If the content of the composition exceeds the upper limit, the content of the inorganic particles will be too high, resulting in excessive scattering, which may make it impossible to improve the brightness of the light-emitting device. The content of the surface modifying material, such as a silane compound or a silicone compound, in the composition of this embodiment can correspond to the content in the dispersion of this embodiment.

[0085] (3.1 Resin Components) When the composition according to this embodiment is used as an encapsulating material, the resin component cures to encapsulate the light-emitting element, thereby preventing deterioration factors from the external environment, such as moisture and oxygen, from reaching the light-emitting element. In this embodiment, the cured product obtained from the resin component is basically transparent, allowing light emitted from the light-emitting element to pass through.

[0086] Such a resin component is not particularly limited as long as it can be used as a sealing material, and examples thereof include silicone resins, epoxy resins, etc. Silicone resins are particularly preferred.

[0087] The silicone resin is not particularly limited as long as it is used as a sealing material, and for example, dimethyl silicone resin, methyl phenyl silicone resin, phenyl silicone resin, organic modified silicone resin, etc. can be used.

[0088] In particular, when a surface modification material having at least one functional group selected from the group consisting of an alkenyl group, an H—Si group, and an alkoxy group is used as the silane compound, it is preferable to use a silicone resin having at least one functional group selected from the group consisting of an H—Si group, an alkenyl group, and an alkoxy group as the silicone resin, for the reasons explained below.

[0089] The alkenyl groups of the silane compound react with the H-Si groups in the silicone resin to crosslink. The H-Si groups of the silane compound react with the alkenyl groups in the silicone resin to crosslink. The alkoxy groups of the silane compound condense with the alkoxy groups in the silicone resin via hydrolysis. This type of bond integrates the silicone resin and the silane compound, improving the strength and density of the resulting sealing component.

[0090] The structure of the resin component may be a two-dimensional chain structure, a three-dimensional network structure, or a cage structure. The resin component may be in a pre-cured state, i.e., a precursor, in the composition as long as it is in a cured polymer state when used as a sealing member. Therefore, the resin component present in the composition may be a monomer, an oligomer, or a polymer.

[0091] The resin component may be of an addition reaction type, a condensation reaction type, or a radical polymerization reaction type. The viscosity of the resin component at 25°C measured in accordance with JIS Z 8803:2011 is, for example, preferably 0.1 Pa·s or more and 100 Pa·s or less, more preferably 1 Pa·s or more and 50 Pa·s or less, and even more preferably 2 Pa·s or more and 10 Pa·s or less.

[0092] Furthermore, the content of the resin component in the composition according to this embodiment is preferably 50% by mass or more and 99% by mass or less, more preferably 55% by mass or more and 98% by mass or less, and even more preferably 60% by mass or more and 97% by mass or less. If the content of the resin component is less than the lower limit, the light emitting element cannot be sufficiently sealed, which may cause deterioration of the light emitting device, and is therefore undesirable. If the content of the resin component exceeds the upper limit, the content of inorganic particles and phosphor particles will be relatively low, which is undesirable because the light emitted from the light-emitting device may not be the desired color or the effect of improving brightness may not be achieved.

[0093] The composition according to this embodiment may contain phosphor particles as long as the object of the present invention is not impaired. The phosphor particles absorb light of a specific wavelength emitted from a light-emitting element and emit light of a predetermined wavelength. In other words, the phosphor particles enable conversion of the wavelength of light and, therefore, adjustment of the color tone.

[0094] There are no particular limitations on the phosphor particles as long as they can be used in a light-emitting device as described below, and they can be appropriately selected and used so that the light-emitting device emits a desired color. The content of the phosphor particles in the composition of this embodiment can be adjusted as appropriate so as to obtain a desired brightness.

[0095] The composition of the present embodiment may also contain commonly used additives such as preservatives, polymerization initiators, polymerization inhibitors, curing catalysts, light diffusing agents, etc., to the extent that the object of the present invention is not impaired. As the light diffusing agent, silica particles having an average particle size of 1 μm or more and 30 μm or less are preferably used.

[0096] (Method of producing the composition) The method for producing the composition of the present embodiment is not particularly limited as long as it allows mixing of the dispersion obtained in the above step with the resin component. Furthermore, materials that are generally contained in sealing members, such as phosphor particles, may be mixed as appropriate.

[0097] <4. Sealing member> The sealing member according to this embodiment is a cured product of the composition according to this embodiment. The sealing member according to this embodiment is usually used as a sealing member disposed on a light-emitting element or as a part thereof.

[0098] The sealing member according to this embodiment can be produced by curing the composition according to this embodiment as described above. The method for curing the composition can be selected depending on the properties of the resin component in the composition according to this embodiment, and examples include heat curing and electron beam curing. More specifically, the sealing member according to this embodiment can be obtained by curing the resin component in the composition according to this embodiment through an addition reaction or a polymerization reaction.

[0099] The thickness and shape of the sealing member according to this embodiment can be adjusted appropriately depending on the desired application and properties, and are not particularly limited.

[0100] The dispersed particle diameter of the inorganic particles in the sealing member is preferably 10 nm or more and 1000 nm or less, more preferably 50 nm or more and 800 nm or less, and even more preferably 60 nm or more and 700 nm or less.

[0101] When the average dispersed particle diameter is 10 nm or more, a sufficient light scattering effect can be obtained, and the light extraction efficiency of the light emitting device can be further improved. On the other hand, when the average dispersed particle diameter is 1000 nm or less, the transmittance of the sealing member can be appropriately increased, and the light extraction efficiency of the light emitting device can be further improved.

[0102] The dispersed particle diameter of the inorganic particles in the sealing member can be measured by observing a sample obtained by cutting the sealing member into thin slices using an electron microscope. However, since it is difficult to observe all of the surface-modified inorganic particles in the sealing member, it is difficult to uniquely define the particle diameter of the surface-modified inorganic particles in the sealing member. Furthermore, even if the particle diameters are approximately the same, the light transmittance will differ if the degree of aggregation between the particles is different. Therefore, it is difficult to accurately measure the average dispersed particle diameter of the surface-modified inorganic particles in the sealing member. Therefore, it is difficult to identify the characteristics of the sealing member of this embodiment based on the average dispersed particle diameter of the surface-modified inorganic particles. When the sealing member of this embodiment is observed with the transmission electron microscope, the maximum agglomerated particle diameter of the surface-modified inorganic particles observed is preferably 1000 nm or less, more preferably 700 nm or less, even more preferably 500 nm or less, and even more preferably 300 nm or less. When the maximum agglomerated particle diameter of the surface-modified inorganic particles is within the above range, the light emitted from the light-emitting element can be appropriately scattered, thereby improving the brightness of the light-emitting device.

[0103] The sealing member according to this embodiment is a cured product of the composition according to this embodiment, and therefore has excellent light transmittance, and the refractive index-enhancing effect of the inorganic particles and the scattering effect of the light emitted from the light-emitting element are fully exhibited. Therefore, a light-emitting device using the sealing member according to this embodiment has improved brightness of emitted light.

[0104] <5. Light-emitting device> Next, the light emitting device according to this embodiment will be described. The light emitting device according to this embodiment includes the above-mentioned sealing member and a light emitting element sealed in the sealing member. Examples of light-emitting elements include light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), etc. The sealing member according to this embodiment is particularly suitable for sealing light-emitting diodes.

[0105] Hereinafter, the light emitting device according to this embodiment will be described using an example in which the light emitting element is a light emitting diode on a chip, i.e., an LED chip, and the light emitting device is an LED package. Figure 1 is a schematic diagram (cross-sectional view) showing an example of a light emitting device according to an embodiment of the present invention. Note that the size of each component in the figure has been appropriately exaggerated to facilitate explanation, and does not represent the actual dimensions or ratios between components.

[0106] As shown in Figure 1, the light-emitting device (LED package) 1 of this embodiment includes a substrate 2 having a recess 21, a light-emitting element (LED chip) 3 arranged on the bottom surface 21a of the recess 21 of the substrate 2, and a sealing member 4 that covers and seals the light-emitting element 3 in the recess 21.

[0107] The sealing member 4 is made of the sealing member according to the present embodiment described above. Therefore, the sealing member 4 has high light transmittance due to suppressed coloring, and the inorganic particles provide a sufficient refractive index improvement effect and a sufficient scattering effect for light emitted from the light-emitting element 3. This improves the brightness of the light emitted from the light-emitting device 1. Furthermore, phosphor particles 5 are dispersed within the sealing member 4. The phosphor particles 5 convert the wavelength of at least a portion of the light emitted from the light-emitting element 3.

[0108] It should be noted that the light emitting device according to the present invention is not limited to the illustrated embodiment. For example, the light emitting device according to the present invention may not contain phosphor particles in the sealing member. Furthermore, the sealing member according to this embodiment may be present at any position in the light emitting device as long as it can seal the light emitting element. Furthermore, in one embodiment of the present invention, the sealing member is composed of multiple layers, and the configurations of these layers may be the same or different. In this case, any one or more layers are composed of the sealing member according to this embodiment.

[0109] As described above, the light emitting device according to this embodiment has excellent brightness of light because the light emitting element is sealed with the sealing member of this embodiment.

[0110] In the light-emitting device according to this embodiment, the light-emitting element is encapsulated with the composition according to this embodiment as described above. Therefore, in one aspect, the present invention also relates to a method for manufacturing a light-emitting device, which includes a step of encapsulating the light-emitting element using the composition according to this embodiment. In this aspect, the manufacturing method may include a step of mixing the dispersion according to this embodiment with a resin component to produce the composition.

[0111] The light emitting device according to the present embodiment as described above can be used in, for example, a lighting fixture or a display device. Accordingly, one aspect of the present invention relates to a lighting fixture or a display device including the light emitting device according to the present embodiment.

[0112] Examples of lighting fixtures include general lighting devices such as indoor and outdoor lights, and lighting for switches of electronic devices such as mobile phones and office automation equipment. The lighting fixture of this embodiment is equipped with the light-emitting device of this embodiment, and therefore, even if the same light-emitting element is used, the emitted luminous flux is greater than that of conventional lighting fixtures, making it possible to brighten the surrounding environment.

[0113] Examples of display devices include mobile phones, personal digital assistants, electronic dictionaries, digital cameras, computers, televisions, and peripheral devices thereof. The display device according to this embodiment is equipped with the light-emitting device according to this embodiment, and therefore, even if the same light-emitting element is used, the emitted luminous flux is greater than in the conventional case, and, for example, a clearer and brighter display can be produced. [Example]

[0114] The present invention will be described in more detail below with reference to examples and comparative examples. Note that the examples described below are merely examples of the present invention and are not intended to limit the present invention.

[0115] [Example 1] (Preparation of dispersion liquid) (i) Hydrolysis process 90.78 parts by mass of methyltriethoxysilane (product name: KBM-13, manufactured by Shin-Etsu Kogyo Chemical Co., Ltd.), 9.21 parts by mass of water, and 0.01 parts by mass of hydrochloric acid (1N) were prepared and added to a container and mixed to obtain a hydrolyzed liquid. Next, this hydrolyzed liquid was stirred at 60°C for 30 minutes to carry out the hydrolysis treatment of methyltriethoxysilane, thereby obtaining a hydrolyzed liquid.

[0116] (ii) First step A mixed liquid was obtained by mixing 21 parts by mass of zirconium oxide particles having an average primary particle size of 12 nm, 7 parts by mass of the hydrolysis liquid, 30 parts by mass of toluene, and 42 parts by mass of a methoxy group-containing phenyl silicone resin (product name: KR217, manufactured by Shin-Etsu Chemical Co., Ltd.) The content of the zirconium oxide particles in the mixed liquid was 21% by mass, the content of methyltriethoxysilane was 6% by mass, and the total content of the zirconium oxide particles, methyltriethoxysilane, and silicone compound was 69% by mass.

[0117] (iii) Second step This mixture was dispersed in a bead mill at room temperature for 10 hours, after which the beads were removed to obtain a first dispersion.

[0118] (iv) The third step A second dispersion was obtained by mixing 59 parts by mass of the first dispersion and 41 parts by mass of a methoxy group-containing phenyl silicone resin (product name: KR217, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0119] (v) The fourth step The obtained second dispersion was subjected to removal of toluene using an evaporator, thereby obtaining the dispersion of Example 1 (third dispersion).

[0120] (evaluation) "Viscosity measurement" The viscosity of the resulting dispersion was measured in accordance with JIS Z 8803:2011 using a rheometer (product name: Rheostress RS-6000, manufactured by HAAKE) at 25°C and a shear rate of 1 (1 / s), and was found to be 0.1 Pa s. The resulting dispersion was stored at 5°C for 30 days, and then its viscosity was measured at 25°C and a shear rate of 1 (1 / s) using a rheometer (product name: Rheostress RS-6000, manufactured by HAAKE) in accordance with JIS Z 8803:2011. The resulting viscosity of the dispersion was 0.1 Pa·s. Furthermore, after storing the resulting dispersion at 5°C for 100 days, the measured viscosity was 0.1 Pa. The results are shown in Table 1.

[0121] (Preparation of Composition) 0.79 g of the dispersion liquid of Example 1 was mixed with 15.0 g of methylphenyl silicone (product name: KER-2500-A / B, manufactured by Shin-Etsu Chemical Co., Ltd.) so that the total mass of the zirconium oxide particles and surface modifying material and the methylphenyl silicone were mixed in a mass ratio of 5:95, thereby obtaining the composition of Example 1.

[0122] (Preparation of cured product) The composition of Example 1 was filled into a 1 mm thick Teflon (registered trademark) coated SUS container so that the film thickness was 1 mm. The mixture was then heated at 100°C for 2 hours and then at 150°C for 4 hours to obtain a cured product of Example 1. The thickness of the cured product when removed from the container was 1 mm.

[0123] "Measurement of in-line transmittance" The linear transmittance of the cured product of Example 1 was measured using a spectrophotometer (manufactured by JASCO Corporation, model number: V-770). As a result, the linear transmittance of the cured product at a wavelength of 450 nm was 22%, and the linear transmittance of the cured product at a wavelength of 600 nm was 42%. The results are shown in Table 1.

[0124] (LED package fabrication and brightness evaluation) The brightness of the LED package before sealing with the composition of Example 1 was measured by applying a voltage of 3 V and a current of 150 mA to the LED package using a total luminous flux measurement system (manufactured by Otsuka Electronics Co., Ltd.) and measuring the brightness A of the optical element itself.

[0125] A composition (total amount of surface-modified aluminum oxide particles and resin: phosphor particles = 100:38) consisting of 1 part by mass of the composition of Example 1 mixed with 0.38 parts by mass of phosphor particles (yttrium aluminum garnet: YAG) was filled into the lead frame to a thickness of 300 μm. The mixture was then kept at room temperature for 3 hours. The composition was then slowly heated and cured to form the encapsulant of Example 1, and the white LED package of Example 1 was fabricated.

[0126] The brightness B of the obtained white LED package of Example 1 was measured by applying a voltage of 3 V and a current of 150 mA to the LED package using a total luminous flux measurement system (manufactured by Otsuka Electronics Co., Ltd.) and measuring the light. The improvement rate of the brightness B (lm) of the white LED package of Example 1 relative to the brightness A (lm) of the optical element itself was calculated. The results are shown in Table 1.

[0127] [Example 2] (Preparation of dry surface-treated zirconium oxide particles) 70.1 parts by mass of zirconium oxide having an average particle size of 12 nm, 4.3 parts by mass of a methoxy group-containing phenyl silicone resin (product name: KR217, manufactured by Shin-Etsu Chemical Co., Ltd.), and 25.6 parts by mass of methanol were mixed uniformly using a stirrer, dried at 80°C for 3 hours, and then heat-treated at 130°C for 3 hours to obtain dry-treated zirconium oxide. A dispersion liquid of Example 2 was obtained in the same manner as in Example 1, except that dry-processed zirconium oxide particles were used instead of zirconium oxide particles.

[0128] (evaluation) "Viscosity measurement" The viscosity of the resulting dispersion was measured in the same manner as in Example 1. As a result, the viscosity of the dispersion was 0.2 Pa·s. The resulting dispersion was stored at 5°C for 30 days, and then the viscosity of the dispersion was measured in the same manner as in Example 1. The result was that the viscosity of the dispersion was 0.2 Pa s. Furthermore, the resulting dispersion was stored at 5°C for 100 days, and then the viscosity was measured in the same manner as in Example 1, and was also 0.2 Pa. The results are shown in Table 1.

[0129] A composition of Example 2 and a cured product of Example 2 were obtained in the same manner as in Example 1, except that the dispersion of Example 2 was used instead of the dispersion of Example 1. The linear transmittance of the cured product measured in the same manner as in Example 1 is shown in Table 1.

[0130] An LED package of Example 2 was produced in the same manner as in Example 1, except that the composition of Example 2 was used instead of the composition of Example 1. The improvement rate of brightness of the white LED package of Example 2 was calculated in the same manner as in Example 1. The results are shown in Table 1.

[0131] [Comparative Example] (Preparation of dispersion liquid) 30 parts by mass of zirconium oxide particles (manufactured by Sumitomo Osaka Cement Co., Ltd.) having an average primary particle size of 12 nm and 70 parts by mass of the hydrolyzed liquid of Example 1 were mixed to obtain a mixed liquid. This mixture was subjected to dispersion treatment in a beads mill for 11 hours, and then the beads were removed to obtain a first dispersion.

[0132] The obtained first dispersion was heated for 2 hours at 60° C. Next, toluene was added to the dispersion so that the solid content concentration was 40% by mass, and the mixture was heated at 60° C. for 2 hours. Next, toluene was added to the dispersion so that the solid content concentration became 30% by mass, and the mixture was heated at 60°C for 1 hour. Next, toluene was added to the dispersion so that the solid content concentration was 20% by mass, and the mixture was heated at 60° C. for 1 hour to obtain a second dispersion.

[0133] A treatment liquid was obtained by mixing 88.1 parts by mass of the second dispersion, the solid content of which had been adjusted to 20% by mass with toluene, with 11.9 parts by mass of a methoxy group-containing phenyl silicone resin (product name: KR217, manufactured by Shin-Etsu Chemical Co., Ltd.). This treatment liquid was then heated at 110°C for 1 hour to obtain a dispersion (third dispersion). Next, the toluene was removed from the obtained dispersion using an evaporator, thereby obtaining a dispersion of a comparative example. The solid content refers to the residue remaining after removing the volatile components. For example, if 1.2 g of the dispersion is placed in a magnetic crucible and heated on a hot plate at 150°C for 1 hour, the remaining components (inorganic particles, surface modification materials, etc.) that do not volatilize can be considered as the solid content.

[0134] The viscosity of the dispersion of the comparative example was measured in the same manner as in Example 1. As a result, the viscosity of the dispersion of the comparative example immediately after preparation was 0.4 Pa s. The dispersion of the comparative example became cloudy the next day and had increased in viscosity to the point where it lost fluidity.

[0135] "Measurement of in-line transmittance" In the dispersion liquid of the comparative example, it was difficult to remove the solvent and then mix it with the resin component. Therefore, a composition for measurement was prepared and evaluated by mixing the resin component with the dispersion liquid of the comparative example and then removing the toluene according to the following procedure. Toluene was added to the third dispersion of Comparative Example to obtain a dispersion with a solids concentration of 30% by mass. 1.6 g of this dispersion was mixed with 9.0 g of methylphenyl silicone (product name: KER-2500-A / B, manufactured by Shin-Etsu Chemical Co., Ltd.). That is, the total mass of the zirconium oxide particles and surface modification material and the methylphenyl silicone were mixed in a mass ratio of 5:95. The toluene was then removed from this mixture using an evaporator to obtain a comparative composition for measurement. This composition was then used to obtain a cured product in the same manner as in Example 1, and its optical properties were measured. The results are shown in Table 1.

[0136] An LED package of the comparative example was produced in the same manner as in Example 1, except that a comparative composition for measurement was used instead of the composition of Example 1. The improvement rate of brightness of the white LED package of the comparative example was calculated in the same manner as in Example 1. The results are shown in Table 1.

[0137] [Table 1]

[0138] From the results of Examples 1 and 2 and the Comparative Example, it was confirmed that the dispersions of Examples 1 and 2 according to the present invention have excellent storage stability, with their viscosity remaining unchanged for more than one month, even though they do not contain water or an organic solvent for dispersing inorganic particles. Furthermore, it was confirmed that the dispersion of this embodiment suppresses aggregation of inorganic particles when mixed with a resin component, resulting in a small aggregated particle size in the cured product and improved in-line transmittance. Furthermore, the composition obtained using the dispersion of this embodiment had excellent linear transmittance, which indicated that the brightness of the light emitted from the resulting light-emitting device (LED package) could be improved.

[0139] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention. [Explanation of symbols]

[0140] 1. Light-emitting device 2 boards 21 Recess 3 Light-emitting element 4 Sealing member 5. Phosphor particles

Claims

1. A dispersion liquid containing inorganic particles and a surface modification material, At least a portion of the surface modification material is attached to the inorganic particles, the surface modification material includes a silane compound and a silicone compound; The content of the inorganic particles is 1% by mass or more and 30% by mass or less, The viscosity is 100 Pa s or less, A dispersion having a viscosity of 100 Pa·s or less after storage at 5°C for 30 days.

2. The dispersion of claim 1 , wherein the silane compound is an alkylalkoxysilane.

3. A composition comprising the dispersion according to claim 1 or 2 and a resin component.

4. A sealing member which is a cured product of the composition according to claim 3.

5. A light emitting device comprising: the sealing member according to claim 4; and a light emitting element sealed by the sealing member.

6. A lighting fixture comprising the light emitting device according to claim 5.

7. A display device comprising the light-emitting device according to claim 5 .

8. A method for producing the dispersion according to claim 1, a first step of mixing a silane compound, a silicone compound, inorganic particles, and an organic solvent to obtain a mixed liquid; a second step of dispersing the inorganic particles in the mixed liquid to obtain a first dispersion; a third step of mixing the first dispersion with a silicone compound to obtain a second dispersion; a fourth step of removing the organic solvent from the second dispersion to obtain a third dispersion, In the first step, the content of the inorganic particles in the mixed solution is 10% by mass or more and 49% by mass or less, In the first step, the content of the organic solvent in the mixed solution is 1% by mass or more and 50% by mass or less, In the first step, the total content of the silane compound, the silicone compound, and the inorganic particles in the mixed liquid is 50% by mass or more and 99% by mass or less.

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