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

Abstract

To provide dispersion liquid capable of improving lightness of a light-emitting device even in a case where a methyl-based silicone resin is used as a sealing material.SOLUTION: The present invention relates to dispersion liquid containing a metal oxide particle, of which the surface is modified by a surface modification material, and a hydrophobic solvent. In the dispersion liquid, a refraction index of the metal oxide particle is 1.70 or more and 2.00 or less, the surface modification material contains a silane compound and a silicone compound, and the silane compound contains a methyl group containing silane compound. The dispersion liquid and methyl-phenyl-silicone are mixed in such a manner that a mass ratio of total mass of the metal oxide particle and the surface modification material and the methyl-phenyl-silicone is 7:93. In the case of a cured product with a thickness of 1 mm, a dispersion component of the cured product in a wavelength of 450 nm is 17% or more and 38% or less, and a value obtained by dividing the dispersion component of the cured product in the wavelength of 450 nm by a dispersion component of the cured product in a wavelength of 600 nm is 1.25 or more.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Light-emitting diodes (LEDs) are widely used as light sources having advantages such as small size, long service life, and low-voltage driving. The LED chip in an LED package is generally encapsulated with a resin-containing encapsulating material to prevent contact with deterioration factors present in the external environment such as oxygen and moisture. Therefore, light emitted from the LED chip passes through the encapsulating material and is emitted outward. Accordingly, 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 by phosphor particles and then efficiently extract the light to the outside of the LED package.

[0003] To prolong the service life of LEDs, demand for methyl-based silicone resins with high heat resistance as encapsulating resins used in encapsulating materials is increasing. Compared with conventionally commonly used phenyl silicone resins and the like, methyl-based silicone resins have a higher content of methyl groups and a higher degree of hydrophobicity. Therefore, as described in Patent Document 1, even when metal oxide particles with a hydrophobized surface are mixed with a methyl-based silicone resin, there has been a problem that the metal oxide particles aggregate with each other, making it impossible to obtain a transparent composition. Such a problem becomes more prominent as the content of metal oxide particles in the encapsulating material increases.

[0004] Patent Document 2 proposes a dispersion for encapsulating a light-emitting element, etc., wherein surface modification with a high-concentration surface modification material suppresses aggregation of metal oxide particles even in a methyl-based silicone resin with high heat resistance. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2016 / 142992 [Patent Document 2] International Publication No. 2020 / 203462 [Overview of the project] [Problems that the invention aims to solve]

[0006] In light-emitting devices using methyl-based silicone resins, there is a need for further improvement in light brightness.

[0007] The present invention has been made in view of the above circumstances, and aims to provide a dispersion, a composition, a sealing member formed using the composition, a light-emitting device having the sealing member, a lighting fixture and display device equipped with the light-emitting device, and a method for manufacturing the dispersion, which can improve the brightness of a light-emitting device even when a methyl silicone resin is used as the sealing material. [Means for solving the problem]

[0008] To solve the above problems, a first aspect of the present invention provides a dispersion comprising metal oxide particles surface-modified with a surface-modifying material and a hydrophobic solvent, wherein the metal oxide particles have a refractive index of 1.70 or more and 2.00 or less, the surface-modifying material comprises a silane compound and a silicone compound, the silane compound comprises a methyl group-containing silane compound, and when the dispersion and methylphenyl silicone are mixed so that the mass ratio of the total mass of the metal oxide particles and the surface-modifying material to the mass of the methylphenyl silicone is 7:93, and a cured product with a thickness of 1 mm is obtained, the scattering content of the cured product at a wavelength of 450 nm is 17% or more and 38% or less, and the value obtained by dividing the scattering content of the cured product at a wavelength of 450 nm by the scattering content of the cured product at a wavelength of 600 nm is 1.25 or more.

[0009] To solve the above problems, a second aspect of the present invention provides a composition which is a mixture of the above-mentioned dispersion and a resin component.

[0010] To solve the above problems, a third aspect of the present invention provides a sealing member which is a cured product of the above composition.

[0011] To solve the above problems, a fourth aspect of the present invention provides a light-emitting device comprising the sealing member and a light-emitting element sealed by the sealing member.

[0012] To solve the above problems, a fifth aspect of the present invention provides a lighting fixture equipped with the above-mentioned light-emitting device.

[0013] To solve the above problems, a sixth aspect of the present invention provides a display device equipped with the above-mentioned light-emitting device.

[0014] To solve the above problems, a seventh aspect of the present invention is a method for producing the above-mentioned dispersion, comprising: step B of mixing a silane compound and metal oxide particles to obtain a mixed liquid; step C of dispersing the metal oxide particles in the mixed liquid to obtain a first dispersion in which the metal oxide particles are dispersed; step D of adding a hydrophobic solvent to the first dispersion to obtain a second dispersion; and step E of adding a silicone compound to the second dispersion to obtain a third dispersion, wherein the metal oxide particles have a refractive index of 1.70 or more and 2.00 or less, and the silane compound includes a methyl group-containing silane compound and a hydrocarbon group-containing silane compound having 2 or more and 5 or fewer carbon atoms, and the above step In B, the content of the metal oxide particles in the mixed liquid is 10% by mass or more and 49% by mass or less, and the total content of the silane compound and the metal oxide particles in the mixed liquid is 65% by mass or more and 98% by mass or less, and step D is one of the following: step d1, after heating the first dispersion liquid, add the hydrophobic solvent at a rate that does not cause the metal oxide particles to aggregate; step d2, while heating the first dispersion liquid, add the hydrophobic solvent at a rate that does not cause the metal oxide particles to aggregate; or step d3, after adding the hydrophobic solvent at a rate that does not cause the metal oxide particles to aggregate, heat the first dispersion liquid. [Effects of the Invention]

[0015] According to the present invention, there can be provided a dispersion liquid and a composition capable of improving the brightness of a light-emitting device, a sealing member formed using the composition, a light-emitting device having the sealing member, a lighting fixture and a display device provided with the light-emitting device, and a method for producing the dispersion liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a light-emitting device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram illustrating another example of a light-emitting device according to an embodiment of the present invention. [Figure 3] FIG. 3 is a schematic diagram illustrating another example of a light-emitting device according to an embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram illustrating another example of a light-emitting device according to an embodiment of the present invention. [Figure 5] FIG. 5 is a field emission transmission electron microscope image of a cured product of Example 1. [Figure 6] FIG. 6 is a field emission transmission electron microscope image of the cured product of Example 1. [Figure 7] FIG. 7 is a field emission transmission electron microscope image of a cured product of Comparative Example 1. [Figure 8] FIG. 8 is a field emission transmission electron microscope image of the cured product of Comparative Example 1. DESCRIPTION OF THE EMBODIMENTS

[0017] Embodiments of the dispersion liquid, the composition, the sealing member, the light-emitting device, the lighting fixture, the display device, and the method for producing the dispersion liquid according to the present invention will be described. It should be noted that the present embodiment is specifically described to facilitate a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified. Omission, addition, substitution, or modification of amounts, numbers, types, ratios, configurations, positions, orders, ratios and the like can be made without departing from the gist of the present invention.

[0018] First, prior to the detailed description of the present invention, the idea of the present inventors leading to the completion of the present invention will be described. Conventionally, the present inventors have considered that in order to improve the brightness of a light-emitting device using an LED chip, it is important to incorporate metal oxide particles having a higher refractive index into a sealing member. That is, metal oxide particles with a higher refractive index can scatter more light emitted from the light-emitting element and contribute to increasing the refractive index of the sealing member. Therefore, the present inventors have considered that in order to improve the brightness of an LED light-emitting device, it is important to use metal oxide particles having a higher refractive index. However, surprisingly, it has been found that the brightness of an LED package may be improved when aluminum oxide particles having a refractive index of about 1.8 are used, compared to when zirconium oxide particles having a refractive index of about 2.1 are used.

[0019] As a result of investigating the mechanism by which this phenomenon occurs, the present inventors obtained the following findings. Even for metal oxide particles having a refractive index of 2.01 or higher, if a large number of aggregated particles formed by aggregation of metal oxide particles in the sealing member are present, the brightness of the LED light-emitting device may be lower than that obtained when using metal oxide particles having a refractive index of 1.70 or higher and 2.00 or lower. On the other hand, even when using metal oxide particles having a refractive index of 1.70 or higher and 2.00 or lower, if there are only a small number of large aggregated particles of metal oxide particles in the sealing member, the brightness of the LED light-emitting device may be higher than that obtained when using metal oxide particles having a refractive index of 2.01 or higher.

[0020] The following can be inferred from this phenomenon. In an LED light-emitting device, a larger amount of blue light emitted from the light-emitting element should be scattered to bring it into contact with phosphor particles. However, if the light that has come into contact with the phosphor particles and undergone wavelength conversion to the longer wavelength side is excessively scattered, the amount of light emitted from the LED light-emitting device will decrease, resulting in insufficient brightness of the LED light-emitting device. Based on this hypothesis, through trial and error, we discovered that the dispersion that can improve the brightness of LED light-emitting devices is a cured product that does not contain phosphor particles, in which light with a wavelength of 450 nm is easily scattered, while light with a wavelength of 600 nm is not. In other words, we found that the balance between the scattering of light with wavelengths of 450 nm and 600 nm is important.

[0021] In order to scatter the blue light emitted from the LED chip within the encapsulating material, the metal oxide particles in the encapsulating material must be of a certain size or larger. However, if the refractive index of the metal oxide particles is too high, the light whose wavelength has been converted by the phosphor particles will also be easily scattered. As a result, while metal oxide particles with a high refractive index are efficient at scattering the blue light emitted from the LED chip, they tend to hinder the transmission of the light after its wavelength has been converted by the phosphor particles. Consequently, it becomes difficult to efficiently extract the light emitted from the LED chip to the outside of the LED light-emitting device.

[0022] On the other hand, when using metal oxide particles with a refractive index between 1.70 and 2.00, the scattering effect of blue light is inferior to that of metal oxide particles with a refractive index of 2.01 or higher, but it does not hinder the transmission of light after wavelength conversion. As a result, the light emitted from the LED chip can be efficiently extracted to the outside of the LED light-emitting device.

[0023] Based on the above ideas, the inventors have completed a dispersion of the present invention that can obtain desired optical properties at wavelengths of 450 nm and 600 nm using metal oxide particles with a refractive index of 1.70 to 2.00.

[0024] (dispersion) The dispersion of this embodiment comprises metal oxide particles surface-modified with a surface-modifying material and a hydrophobic solvent, wherein the metal oxide particles have a refractive index of 1.70 or more and 2.00 or less, the surface-modifying material comprises a silane compound and a silicone compound, the silane compound comprises a methyl group-containing silane compound, and when the dispersion and methylphenyl silicone are mixed such that the mass ratio of the total mass of the metal oxide particles and surface-modifying material to the mass of methylphenyl silicone is 7:93, and a cured product with a thickness of 1 mm is obtained, the scattering portion of the cured product at a wavelength of 450 nm is 17% or more and 38% or less, and the value obtained by dividing the scattering portion of the cured product at a wavelength of 450 nm by the scattering portion of the cured product at a wavelength of 600 nm is 1.25 or more. The dispersion in this embodiment is for sealing the light-emitting element.

[0025] The above-mentioned silane compound may also include a hydrocarbon group-containing silane compound having 2 to 5 carbon atoms, in addition to a methyl group-containing silane compound. When the silane compound includes a hydrocarbon group-containing silane compound having 2 to 5 carbon atoms, the mass ratio of the methyl group-containing silane compound to the hydrocarbon group-containing silane compound having 2 to 5 carbon atoms is preferably in the range of 99:1 to 35:65.

[0026] In this embodiment, "scattering component" refers to the value obtained by subtracting the linear transmittance (%) value from the integral transmittance (%) value. Integral transmittance refers to the transmittance measured using an integrating sphere in a spectrophotometer. Linear transmittance refers to the transmittance measured using a spectrophotometer without using an integrating sphere.

[0027] When the above dispersion and methylphenyl silicone are mixed so that the mass ratio of the total mass of metal oxide particles and surface modification material to the mass of methylphenyl silicone is 7:93, and a 1 mm thick cured product is obtained, the scattering content of the cured product at a wavelength of 450 nm is 17% or more and 38% or less, and more preferably 20% or more and 35% or less. By having a scattering content of 17% or more at a wavelength of 450 nm in the cured product, light emitted from the light-emitting element can be sufficiently scattered. Furthermore, by having a scattering content of 38% or less at a wavelength of 450 nm in the cured product, a sealing member with a good balance of scattering of light at wavelengths of 450 nm and 600 nm can be obtained.

[0028] The value obtained by dividing the scattering portion of the cured product at a wavelength of 450 nm by the scattering portion of the cured product at a wavelength of 600 nm is 1.25 or greater, preferably 1.27 or greater, and more preferably 1.29 or greater. The upper limit of the value obtained by dividing the scattering portion of the cured product at a wavelength of 450 nm by the scattering portion of the cured product at a wavelength of 600 nm is not particularly limited and may be 2.00 or less, 1.80 or less, or 1.60 or less. If the value obtained by dividing the scattering component of the cured material at a wavelength of 450 nm by the scattering component of the cured material at a wavelength of 600 nm is 1.25 or higher, then low-wavelength light is scattered while the scattering of high-wavelength light is suppressed, thereby improving the brightness of the light emitted by the light-emitting device.

[0029] The scattering content of the cured product at a wavelength of 600 nm is preferably 13% to 29%, and more preferably 14% to 28%. By having the scattering content of the cured product at a wavelength of 600 nm within this range, it becomes easy to control the value obtained by dividing the scattering content of the cured product at a wavelength of 450 nm by the scattering content of the cured product at a wavelength of 600 nm to 1.25 or higher.

[0030] In this embodiment, "when the total mass of metal oxide particles and surface modification material is mixed with methylphenyl silicone in a mass ratio of 7:93 to form a 1 mm thick cured product" means that a 1 mm thick cured product is formed using only metal oxide particles, surface modification material, methylphenyl silicone, and the curing agent necessary to cure the methylphenyl silicone. In other words, it means that materials generally included in sealing members, such as phosphor particles, are not included in the cured product. Phosphorescent particles and the like affect the optical properties of the cured product, thus hindering the measurement of the scattering properties of the metal oxide particles. Therefore, the above cured product is formed from only the metal oxide particles, surface modification material, methylphenyl silicone, and materials necessary for curing the methylphenyl silicone. Any material that does not hinder the scattering properties of the metal oxide particles may be included in the above cured product. The reason for using methylphenyl silicone when forming the 1 mm thick cured product described above is that, compared to conventional phenyl-based silicones, it is more prone to generating excessively aggregated particles in the cured product, making it difficult to obtain the desired scattering characteristics. If a dispersion liquid using methylphenyl silicone, which has excellent heat resistance, can be used to obtain the desired scattering characteristics, the brightness of the light-emitting device can be improved regardless of the type of resin component.

[0031] The dispersion of this embodiment contains metal oxide particles (hereinafter sometimes abbreviated as "surface-modified metal oxide particles") in which metal oxide particles with a refractive index of 1.70 to 2.00 are densely surface-modified with a surface-modifying material containing a methyl group-containing silane compound and a silicone compound, by a manufacturing method described later. The dispersion of this embodiment can disperse the surface-modified metal oxide particles of this embodiment in a size that scatters light with a wavelength of 450 nm above a certain level while suppressing the scattering of light with a wavelength of 600 nm within the sealing member. Therefore, the brightness of the light-emitting device can be improved by using the dispersion of this embodiment.

[0032] In the composition of this embodiment, since surface-modified metal oxide particles obtained by the manufacturing method described later are used, it is considered that the aggregation state of the surface-modified metal oxide particles in the sealing member can be controlled to a desired size. In other words, by directly dispersing the metal oxide particles in a methyl group-containing silane compound, uniform mixing is possible even if the resin component is a methyl-based silicone resin. It is presumed that the surface-modified metal oxide particles in this embodiment have more silane compound adhering to them and are denser than conventional surface-modified metal oxide particles.

[0033] It is unclear what surface conditions of the metal oxide particles enable the scattering of the cured product at wavelengths of 450 nm and 600 nm to reach the desired values. Therefore, it is difficult to directly identify the characteristics of the dispersion in this embodiment based on the surface conditions of the metal oxide particles modified with the methyl group-containing silane compound and the silicone compound. Furthermore, it is not easy to specify in words the surface condition required to disperse the surface-modified metal oxide particles in the cured material in a manner that yields the desired scattering characteristics. This is because the ability to disperse the surface-modified metal oxide particles in the sealing member in a manner that yields the desired scattering characteristics is presumed to be due to a complex interplay of numerous factors, such as the structure of the surface-modifying material, the degree of polymerization of the surface-modifying material, the characteristics of the metal oxide particles, and the characteristics of the sealing resin.

[0034] However, the present invention makes it possible to easily provide a sealing member that can improve the brightness of a light-emitting device by evaluating and adjusting the dispersion of surface-modified metal oxide particles using the scattering components at a wavelength of 450 nm and 600 nm of the cured material. In this invention, the scattering characteristics of the cured product at a wavelength of 450 nm and at a wavelength of 600 nm were controlled considering the influence of a blue LED. However, if the color emitted from the light-emitting element is other than blue, the degree of dispersion of the surface-modified metal oxide particles in the dispersion should be controlled so that the wavelength of the emitted color and the scattering characteristics at a wavelength of 600 nm are within the desired range. Furthermore, if it is difficult to control the scattering characteristics of the cured product at a wavelength of 450 nm and 600 nm solely by the dispersion of surface-modified metal oxide particles in the dispersion, the refractive index of the metal oxide particles can be adjusted to control the scattering characteristics of the cured product at a wavelength of 450 nm and 600 nm within the desired range. If metal oxide particles with a refractive index between 1.70 and 2.00 are used, the light scattering effect will be smaller than that of metal oxide particles with a refractive index of 2.01 or higher, even if the particle size of the surface-modified metal oxide particles in the sealing material is somewhat larger. Therefore, by dispersing metal oxide particles with a refractive index between 1.70 and 2.00 in the sealing material to the extent that they do not aggregate excessively, a sealing material with an excellent scattering balance between light at wavelengths of 450 nm and 600 nm can be obtained. Furthermore, a light-emitting device equipped with a sealing material made using such a dispersion will exhibit improved light brightness.

[0035] It is cumbersome to adjust the type of metal oxide particles, surface modification material, their content, and dispersion conditions each time the type of resin component for encapsulating the light-emitting element changes. However, according to the present invention, it has been found that the brightness of the LED light-emitting device can be improved by controlling the dispersion state of the surface-modified metal oxide particles in the dispersion so that the scattering characteristics of the cured product at a wavelength of 450 nm and at a wavelength of 600 nm are within the desired range.

[0036] The following describes each component included in this embodiment. (metal oxide particles) The metal oxide particles scatter the light emitted from the light-emitting element within the sealing member described later. Furthermore, depending on the type of metal oxide particle, it improves the refractive index of the sealing member. Through these means, the metal oxide particles contribute to improving the brightness of the light in the light-emitting device.

[0037] The above metal oxide particles have a refractive index of 1.70 to 2.00, and more preferably 1.80 to 1.98. Examples of metal oxide particles that can be used in this embodiment include aluminum oxide particles, yttrium oxide particles, and hafnium oxide particles. Aluminum oxide particles are preferred because they allow for easy control of the dispersion during dispersion preparation.

[0038] The metal oxide particles may be dispersed as primary particles in the dispersion, or as secondary particles formed by the aggregation of primary particles. Typically, the metal oxide particles are dispersed as secondary particles.

[0039] In the dispersion of this embodiment, the average dispersed particle diameter of the metal oxide particles is not particularly limited, as long as the dispersed particle diameter (aggregated particle diameter) in the sealing member is 60 nm or more and 1000 nm or less. The average dispersed particle diameter of the metal oxide particles may be, for example, 30 nm or more and 1000 nm or less, 50 nm or more and 800 nm or less, or 60 nm or more and 700 nm or less. The aggregation state of metal oxide particles in the cured product varies depending on the combination of metal oxide particles, surface modification materials, resin components, and phosphor particles, as well as the curing conditions of the composition. Therefore, the average dispersed particle size of metal oxide particles in the dispersion should be adjusted while checking the scattering characteristics at wavelengths of 450 nm and 600 nm in the 1 mm thick cured product. The average dispersed particle size of metal oxide particles can be measured, for example, using a particle size distribution device.

[0040] The average dispersed particle diameter of metal oxide particles is measured and calculated based on the diameter of the dispersed metal oxide particles, regardless of whether the metal oxide particles are dispersed as primary or secondary particles. In this embodiment, the average dispersed particle diameter of metal oxide particles may also be measured as the average dispersed particle diameter of metal oxide particles to which the surface modification material is attached. In a dispersion, there may be metal oxide particles to which the surface modification material is attached and metal oxide particles to which the surface modification material is not attached. Therefore, the average dispersed particle diameter of metal oxide particles is usually measured as the value in a mixed state of these particles.

[0041] The average primary particle diameter of the metal oxide particles can be arbitrarily selected, but is preferably 3 nm to 200 nm, more preferably 5 nm to 170 nm, and even more preferably 10 nm to 100 nm. The average primary particle diameter of the metal oxide particles may be 5 nm to 20 nm, 5 nm to 25 nm, 50 nm to 120 nm, or 50 nm to 150 nm, as needed. Having the average primary particle diameter of the metal oxide particles within the above range is preferable because it facilitates the control of the scattering characteristics of the cured product at a wavelength of 450 nm and at a wavelength of 600 nm.

[0042] The average primary particle diameter of metal oxide particles can be measured by any method of choice. For example, it can be done by observation with a transmission electron microscope. For instance, a predetermined number of metal oxide particles, for example 100, are selected from the transmission electron microscope image. Then, the longest linear segment (maximum major axis) of each of these metal oxide particles is measured, and the average primary particle diameter of the metal oxide particles is determined by arithmetic mean of these measurements.

[0043] In cases where metal oxide particles are aggregated, the aggregate particle diameter is not measured. Instead, the maximum major diameter of a predetermined number of metal oxide particles (primary particles) constituting the aggregate is measured and used as the average primary particle diameter.

[0044] The content of metal oxide particles in the dispersion is not particularly limited, as long as it can be mixed with the resin components described later. The content of metal oxide particles in the dispersion can be arbitrarily selected, but for example, it is preferably 1% by mass or more and 70% by mass or less, more preferably 5% by mass or more and 50% by mass or less, even more preferably 7% by mass or more and 40% by mass or less, and particularly preferably 10% by mass or more and 30% by mass or less. If necessary, it may be 20% by mass or more and 40% by mass or 25% by mass or more and 35% by mass or less.

[0045] This amount prevents the viscosity of the dispersion from becoming excessively high. This facilitates mixing with the resin component, which will be discussed later. Furthermore, it prevents an excess of solvent (dispersion medium) after mixing with the resin component, making solvent removal easier.

[0046] The metal oxide particles described above have a surface modification material attached to their surface, as described below. This attachment allows the metal oxide particles to be dispersed in the resin component at a desired particle size.

[0047] (Surface modification material) The dispersion of this embodiment contains a silane compound and a silicone compound as surface modification materials, and the silane compound contains a methyl group-containing silane compound. In this embodiment, only the silane compound and the silicone compound may be used as surface modification materials. In the dispersion of this embodiment, at least a portion of the surface-modifying material adheres to the surface of the metal oxide particles, modifying the surface and thereby preventing aggregation of the metal oxide particles. Furthermore, this adhesion improves compatibility with the resin component.

[0048] Here, "adhesion" of the surface-modifying material to the metal oxide particles means that the surface-modifying material comes into contact with or bonds to the metal oxide particles through interactions or reactions between them. Examples of contact include physical adsorption. Examples of bonding include ionic bonds, hydrogen bonds, and covalent bonds. In this embodiment, the metal oxide particles may be surface-modified with at least a silane compound and a silicone compound.

[0049] Silane compounds tend to adhere to the surface of metal oxide particles. On the other hand, silicone compounds have relatively large molecular weights and mainly contribute to improving affinity with dispersion media and resin components. By using such silane compounds, the dispersion stability of metal oxide particles in resin components is improved. Using a silane compound and a silicone compound in combination is preferable because it further improves the dispersion stability of metal oxide particles in the resin component. The surface modification material may include components other than silane compounds and silicone compounds, provided that it does not hinder the objectives of the present invention. Examples of such components include carbon-carbon unsaturated bond-containing fatty acids, specifically methacrylic acid, acrylic acid, and the like.

[0050] (Silane compounds) The silane compound in this embodiment includes a methyl group-containing silane compound. By surface-modifying the metal oxide particles with the methyl group-containing silane compound using a manufacturing method described later, excessive aggregation of metal oxide particles within the sealing member can be suppressed, even in the case of a methyl-based silicone resin. From the viewpoint of having low viscosity and facilitating the dispersion of metal oxide particles in the dispersion process described later, the methyl group-containing silane compound preferably further contains an alkoxy group. The number of alkoxy groups in such a silane compound containing methyl and alkoxy groups is preferably 1 to 3, and more preferably 3. The number of alkoxy groups may be 1 or 2 as needed. The number of carbon atoms in the alkoxy group can be arbitrarily selected, but is preferably 1 to 5. The number of carbon atoms may be 1 to 3, or 2 to 4.

[0051] Examples of such methyl group-containing silane compounds include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, diethoxymonomethylsilane, monoethoxydimethylsilane, dimethylchlorosilane, and methyldichlorosilane. The above methyl group-containing silane compound may preferably contain at least one selected from the group consisting of the above compounds. It is preferable to use methyltrimethoxysilane and methyltriethoxysilane in terms of their tendency to adhere to the surface of metal oxide particles. It is preferable to use methyltriethoxysilane in terms of improving the dispersion stability of the above surface-modified metal oxide particles.

[0052] The silane compound may be a methyl group-containing silane compound or a hydrocarbon group-containing silane compound with 2 to 5 carbon atoms. From the viewpoint of densely treating the surface of metal oxide particles, it is preferable to use only methyl group-containing silane compounds. However, if the surface-modified metal oxide particles are excessively aggregated in the sealing member, it is preferable to use a combination of methyl group-containing silane compounds and hydrocarbon group-containing silane compounds with 2 to 5 carbon atoms to improve compatibility with the resin component.

[0053] From the viewpoint of having low viscosity and facilitating the dispersion of metal oxide particles in the dispersion process described later, the hydrocarbon group-containing silane compound having 2 to 5 carbon atoms is preferably further containing an alkoxy group. The number of alkoxy groups in the silane compound containing the hydrocarbon group and alkoxy group described above is preferably 1 to 3, and more preferably 3. The number of alkoxy groups may be 1 or 2 as needed. The number of carbon atoms in the alkoxy group can be arbitrarily selected, but is preferably 1 to 5. The number of carbon atoms in the alkoxy group may be 1 to 3, or 2 to 4.

[0054] The hydrocarbon group having 2 to 5 carbon atoms is not particularly limited as long as it is easily compatible with the resin component. Considering the ease of surface modification on the metal oxide particle surface, a carbon number of 2 to 4 is more preferable. The hydrocarbon group having 2 to 5 carbon atoms may be a chain-type aliphatic hydrocarbon group or a cyclic aliphatic hydrocarbon group.

[0055] The hydrocarbon group having 2 to 5 carbon atoms may be an alkyl group, an alkenyl group, or an alkynyl group. Examples of alkyl groups that can be used include ethyl, propyl, butyl, and pentyl groups. Examples of alkenyl groups that can be used include vinyl, allyl, propenyl, and butenyl groups. Examples of alkynyl groups that can be used include ethynyl, propynyl, and butynyl groups.

[0056] Examples of hydrocarbon group-containing silane compounds having 2 to 5 carbon atoms include ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, propyltrimethoxysilane, propyltriethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, diethylchlorosilane, and ethyldichlorosilane. These hydrocarbon group-containing silane compounds having 2 to 5 carbon atoms may be used individually or in combination of two or more. Among these, silane compounds having an alkoxy group, particularly a methoxy group, are preferred because they readily adhere to metal oxide particles. Among these, silane compounds having an ethoxy group are preferred in terms of improving the dispersion stability of surface-modified metal oxide particles.

[0057] When using the methyl group-containing silane compound and the hydrocarbon group-containing silane compound having 2 to 5 carbon atoms as the silane compound, it is preferable that the mass ratio of the methyl group-containing silane compound to the hydrocarbon group-containing silane compound having 2 to 5 carbon atoms is in the range of 99:1 to 35:65. By having the mass ratio of the methyl group-containing silane compound to the hydrocarbon group-containing silane compound having 2 to 5 carbon atoms within the above range, the metal oxide particles are densely surface-modified, and even when mixed with a methyl-based silicone resin, excessive aggregation of the surface-modified metal oxide particles is suppressed.

[0058] The content of the silane compound in the dispersion can be arbitrarily selected and is not particularly limited, but it is preferably 50 parts by mass or more and 500 parts by mass or less, more preferably 70 parts by mass or more and 400 parts by mass or less, and even more preferably 90 parts by mass or more and 300 parts by mass or less, per 100 parts by mass of metal oxide particles. If necessary, the content of the silane compound in the dispersion may be 80 parts by mass or more and 350 parts by mass or 150 parts by mass or more and 250 parts by mass or less. This allows a sufficient amount of silicone compound to adhere to the surface of the metal oxide particles via the silane compound. Therefore, the dispersion stability of the metal oxide particles can be improved, and the dispersibility of the metal oxide particles in the resin component can be improved even if the resin component is a methyl-based silicone resin.

[0059] (Silicone compounds) The silicone compound can be arbitrarily selected and examples include alkoxy group-containing phenyl silicone, dimethyl silicone, methylphenyl silicone, methyl hydrogen silicone, methylphenyl hydrogen silicone, diphenyl hydrogen silicone, alkoxy-terminal phenyl silicone, alkoxy-terminal methylphenyl silicone, alkoxy group-containing methylphenyl silicone, alkoxy group-containing dimethyl silicone, alkoxy-partial-terminal trimethyl-partial-terminal (methyl group-partial-terminal) dimethyl silicone, and alkoxy group-containing phenyl silicone. These silicone compounds may be used individually or in combination of two or more. The silicone compound may be a monomer, an oligomer, or a resin (polymer). It is preferable to use a monomer or oligomer because surface modification is easier.

[0060] Among those mentioned above, from the viewpoint of ease of reaction and high hydrophobicity, the silicone compounds are preferably alkoxy group-containing phenyl silicone, dimethyl silicone, methylphenyl silicone, alkoxy-terminalized phenyl silicone, alkoxy-terminalized methylphenyl silicone, alkoxy group-containing methylphenyl silicone, alkoxy group-containing dimethyl silicone, alkoxy-partial-terminal trimethyl-partial-terminal (methyl-partial-terminal) dimethyl silicone, and alkoxy group-containing phenyl silicone. At least one selected from the group consisting of these compounds may be included. More preferably, the silicone compound includes at least one selected from the group consisting of methoxy group-containing phenyl silicone, dimethyl silicone, and methoxy group-containing dimethyl silicone.

[0061] The content of the silicone compound in the dispersion can be arbitrarily selected and is not particularly limited. For example, per 100 parts by mass of metal oxide particles, it is preferably 50 parts by mass or more and 500 parts by mass or less, more preferably 80 parts by mass or more and 400 parts by mass or less, and even more preferably 100 parts by mass or more and 300 parts by mass or less. If necessary, the content of the silicone compound in the dispersion may be 50 parts by mass or more and 200 parts by mass or 50 parts by mass or more and 150 parts by mass or less. This allows a sufficient amount of silicone compound to adhere to the surface of the metal oxide particles, improving the dispersion stability of the metal oxide particles and improving their dispersibility in the resin component. Furthermore, the amount of free silicone compound can be reduced, and unintended aggregation of metal oxide particles in the resin component can be suppressed.

[0062] (Total content of silane compounds and silicone compounds) The total content of silane compounds and silicone compounds is not particularly limited and can be arbitrarily selected. The total content of silane compounds and silicone compounds is preferably, for example, 100 parts by mass or more and 1000 parts by mass or less, more preferably 150 parts by mass or more and 800 parts by mass or less, and even more preferably 190 parts by mass or more and 600 parts by mass or less, per 100 parts by mass of metal oxide particles. The total content of silane compounds and silicone compounds may also be 200 parts by mass or more and 900 parts by mass or less, or 250 parts by mass or more and 850 parts by mass or less. When the total content of silane compounds and silicone compounds is within the above range, the dispersibility of metal oxide particles can be sufficiently improved while reducing the amount of free surface modification material.

[0063] (Hydrophobic solvent) The dispersion of this embodiment contains a hydrophobic solvent as a dispersion medium for dispersing surface-modified metal oxide particles. This hydrophobic solvent is not particularly limited as long as it can disperse metal oxide particles to which the surface-modified material is attached and can be mixed with the resin component described later. Examples of such hydrophobic solvents include aromatics, saturated hydrocarbons, and unsaturated hydrocarbons. These hydrophobic solvents may be used individually or in combination of two or more. Examples of such hydrophobic solvents include aromatics, saturated hydrocarbons, and unsaturated hydrocarbons. These hydrophobic solvents may be used individually or in combination of two or more.

[0064] Among the above, aromatics, particularly aromatic hydrocarbons, are preferred as hydrophobic solvents. Aromatics have excellent compatibility with resin components, which contributes to improving the viscosity properties of the resulting composition and the quality (transparency, shape, etc.) of the formed sealing member.

[0065] Examples of such aromatic hydrocarbons include benzene, toluene, ethylbenzene, 1-phenylpropane, isopropylbenzene, n-butylbenzene, tert-butylbenzene, sec-butylbenzene, o-xylene, m-xylene or p-xylene, 2-ethyltoluene, 3-ethyltoluene or 4-ethyltoluene, and the like. These aromatic hydrocarbons may be used individually or in combination of two or more.

[0066] Among those mentioned above, from the viewpoint of the stability of the dispersion and ease of handling in the removal of hydrophobic solvents during the production of the composition described later, at least one hydrophobic solvent selected from the group consisting of toluene, o-xylene, m-xylene or p-xylene, and benzene is particularly preferred.

[0067] The amount of hydrophobic solvent contained in the dispersion can be arbitrarily selected, but it should be adjusted as appropriate to achieve the desired solid content concentration. The hydrophobic solvent content is preferably 40% to 95% by mass, more preferably 50% to 90% by mass, and even more preferably 60% to 80% by mass. This makes it easier to mix the dispersion with the resin components described later, particularly the methyl-based silicone resin. If necessary, the hydrophobic solvent content may be 60% to 90% by mass, 65% to 85% by mass, or 70% to 80% by mass. In this embodiment, the solid content refers to the residue remaining after removing volatile components. For example, when 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 components that remain without volatilizing (such as metal oxide particles or surface modification materials) can be considered the solid content.

[0068] (hydrophilic solvent) The dispersion in this embodiment may contain a hydrophilic solvent. The hydrophilic solvent may be included in the dispersion by, for example, a method described later. Examples of such hydrophilic solvents include alcohol-based solvents, ketone-based solvents, nitrile-based solvents, and the like. These hydrophilic solvents may be used individually or in combination of two or more.

[0069] Examples of alcohol-based solvents include branched or linear alcohol compounds having 1 to 4 carbon atoms and their ether condensates. These alcohol-based solvents may be used individually or in combination of two or more. The alcohol compound contained in the alcohol-based solvent may be a primary alcohol, a secondary alcohol, or a tertiary alcohol. Furthermore, the alcohol compound contained in the alcohol-based solvent may be a monohydric alcohol, a dihydric alcohol, or a trihydric alcohol. More specifically, examples of alcohol-based solvents include methanol, ethanol, 1-propanol, isopropyl alcohol, 1-butyl alcohol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, methanediol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-butene-1,4-diol, 1,4-butynediol, glycerin, diethylene glycol, and 3-methoxy-1,2-propanediol.

[0070] Examples of ketone solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of nitrile solvents include acetonitrile.

[0071] From the viewpoint of having excellent affinity for water and hydrophobic solvents and promoting their miscibility, hydrophilic solvents preferably include alcohol-based solvents. In this case, the number of carbon atoms in the alcohol compound constituting the alcohol-based solvent is preferably 1 to 3, and more preferably 1 to 2. Among hydrophilic solvents, methanol and ethanol, particularly methanol, can be preferably used because they can fully exhibit the effects of the alcohol-based solvents mentioned above.

[0072] Furthermore, the content of the hydrophilic solvent in the dispersion is preferably 10% by mass or less, more preferably 7% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less. The content of the hydrophilic solvent may also be 0% by mass.

[0073] (Other ingredients) The dispersion of this embodiment may contain components other than those described above. For example, the dispersion of this embodiment may contain, as necessary, other components such as dispersants, dispersion aids, antioxidants, flow regulators, thickeners, pH adjusters, preservatives, and other general additives. Furthermore, the dispersion of this embodiment may contain components that may be present due to the method described later, such as acid, water, alcohol, etc.

[0074] In this specification, the dispersion of this embodiment is distinguished from the composition of this embodiment which contains a resin component and can form a sealing member by curing. That is, even if the dispersion of this embodiment contains a resin component described later, it does not contain the resin component described later in an amount sufficient to form a sealing member when simply cured. More specifically, the mass ratio of the resin component to the metal oxide particles in the dispersion of this embodiment is preferably in the range of 0:100 to 40:60, more preferably in the range of 0:100 to 30:70, and even more preferably in the range of 0:100 to 20:80. The dispersion of this embodiment is particularly preferably essentially free of the resin component described later, and most preferably completely free of the resin component described later.

[0075] In this embodiment, the dispersion is manufactured by a method described later, and the surface of metal oxide particles with a refractive index of 1.70 to 2.00 is sufficiently modified with a surface modification material. These modified metal oxide particles exhibit excellent affinity even in methyl-based silicone resins and can be dispersed in methyl-based silicone resins with a desired degree of dispersion that exhibits excellent scattering characteristics. Methyl-based silicone resins are more prone to aggregation of surface-modified metal oxide particles compared to conventional phenyl-based silicone resins. However, for metal oxide particles with a refractive index of 1.70 to 2.00, this tendency to aggregate actually brings the scattering characteristics of the cured material at wavelengths of 450 nm and 600 nm within the desired range. As a result, the sealing member formed using the dispersion of this embodiment can improve the brightness of the light-emitting device.

[0076] (Method for producing dispersion) The method for producing the dispersion of this embodiment includes step B, which involves mixing a silane compound and metal oxide particles to obtain a mixed solution, Step C involves dispersing the metal oxide particles in the aforementioned mixture to obtain a first dispersion in which the metal oxide particles are dispersed. Step D involves adding a hydrophobic solvent to the first dispersion to obtain a second dispersion, The process includes step E, which involves adding a silicone compound to the second dispersion to obtain a third dispersion. The metal oxide particles have a refractive index of 1.70 or more and 2.00 or less. The silane compound includes a methyl group-containing silane compound. In step B, the content of the metal oxide particles in the mixed liquid is 10% by mass or more and 49% by mass or less, and the total content of the silane compound and the metal oxide particles in the mixed liquid is 65% by mass or more and 98% by mass or less. Step D is one of the following: step d1, which involves heating the first dispersion and then adding the hydrophobic solvent at a rate that does not cause the metal oxide particles to aggregate; step d2, which involves heating the first dispersion while adding the hydrophobic solvent at a rate that does not cause the metal oxide particles to aggregate; or step d3, which involves adding the hydrophobic solvent at a rate that does not cause the metal oxide particles to aggregate and then heating the first dispersion.

[0077] The above-mentioned silane compound may contain, in addition to the methyl group-containing silane compound, a hydrocarbon group-containing silane compound having 2 to 5 carbon atoms. When the above silane compound contains a hydrocarbon group-containing silane compound having 2 to 5 carbon atoms, it is preferable that the mass ratio of the methyl group-containing silane compound and the hydrocarbon group-containing silane compound having 2 to 5 carbon atoms is in the range of 99:1 to 35:65.

[0078] The total content of the silane compound and the metal oxide particles can also be evaluated based on the solid content.

[0079] The total content of the silane compound and metal oxide particles described above does not include the alcohol generated by the hydrolysis of the silane compound, as described later. In other words, the total content of the silane compound and metal oxide particles refers to the total content of the silane compound, the hydrolyzed silane compound, and the metal oxide particles. It goes without saying that the total content includes the content of metal oxide particles attached to the silane compound.

[0080] Furthermore, in this embodiment, prior to each of the above steps, there may be a step A (hydrolysis step) in which the silane compound and water are mixed to obtain a hydrolysis solution containing the hydrolyzed silane compound. The following describes in detail each step for obtaining the dispersion according to this embodiment.

[0081] (Process A (hydrolysis process)) 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 a mixture in which at least a portion of the silane compound has been hydrolyzed in advance, the silane compound is more likely to adhere to the metal oxide particles in the dispersion step described later.

[0082] As the silane compound, one of the methyl group-containing silane compounds from the above-mentioned silane compounds may be used alone, or two or more may be used in combination. Furthermore, the content of the silane compound in the hydrolysis solution is not particularly limited. It can be the remainder after removing other components from the hydrolysis solution, but for example, it is preferably 60% by mass or more and 99% by mass or less, more preferably 70% by mass or more and 97% by mass or less, and even more preferably 80% by mass or more and 95% by mass or less. The content of the silane compound in the hydrolysis solution may be 85% by mass or more and 95% by mass or 87% by mass or more and 93% by mass or less, as needed. When using two or more silane compounds in combination, each compound may be hydrolyzed individually, or the two or more silane compounds may be hydrolyzed together as a mixture.

[0083] Furthermore, surface modification materials other than silane compounds may be included in the hydrolysis solution during the hydrolysis process.

[0084] Furthermore, in the hydrolysis process, the hydrolysis solution contains water. Water serves as a substrate for the hydrolysis reaction of surface-modifying materials such as silane compounds. The water content in the hydrolysis solution is not particularly limited and can be arbitrarily selected. For example, the water content can be appropriately set in accordance with the amount of 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 metal oxide particles in the dispersion produced by the excess amount of water.

[0085] Alternatively, the water content in the hydrolysis solution is preferably, for example, 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.

[0086] Furthermore, a catalyst may be added to the hydrolysis solution along with the silane compound and water. For example, an acid or a base can be used as the catalyst. The acid catalyzes the hydrolysis reaction of the silane compound in the hydrolysis solution. On the other hand, the base catalyzes the condensation reaction between the hydrolyzed silane compound and the functional groups on the surface of the metal oxide particles, such as hydroxyl groups and silanol groups. These reactions make it easier for the silane compound, including the silane compound itself, to adhere to the metal oxide particles in the dispersion step (step C) described later, thereby improving the dispersion stability of the metal oxide particles.

[0087] Here, the term "acid" refers to an acid based on the so-called Brønsted-Lowry definition, and is a substance that donates protons in the hydrolysis reaction of surface-modifying materials such as silane compounds. The term "base" also refers to a base based on the so-called Brønsted-Lowry definition, and here it refers to a substance that accepts protons in the hydrolysis reaction and subsequent condensation reaction of surface-modifying materials such as silane compounds.

[0088] The acid is not particularly limited as long as it can supply protons in the hydrolysis reaction of the silane compound, and can be arbitrarily selected. Examples of such acids include inorganic acids such as hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, boric acid, and phosphoric acid, as well as organic acids such as acetic acid, citric acid, and formic acid. These acids may be used individually or in combination of two or more.

[0089] The base is not particularly limited as long as it can accept protons in the hydrolysis reaction of the silane compound, and can be arbitrarily selected. Examples of bases include sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide, ammonia, and amines. These bases may be used individually or in combination of two or more.

[0090] Among the above, it is preferable to use an acid as the catalyst. From the viewpoint of acidity, inorganic acids are preferred, and hydrochloric acid is more preferred.

[0091] 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 the 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. Furthermore, when using an acid such as hydrochloric acid (1N) 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.

[0092] Furthermore, the hydrolysis solution may contain a hydrophilic solvent as needed. The hydrophilic solvent promotes the miscibility of water and the silane compound in the hydrolysis solution, thereby further accelerating the hydrolysis reaction of the silane compound.

[0093] Examples of such hydrophilic solvents include the various hydrophilic solvents that may be contained in the dispersion described above. 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.

[0094] Among those mentioned above, 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, from the viewpoint of having excellent affinity for water and hydrophobic solvents and promoting their miscibility.

[0095] Furthermore, the content of the hydrophilic solvent in the hydrolysis solution 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. Within this range, the content of the silane compound and water in the hydrolysis solution can be sufficiently high. The hydrophilic solvent content in the hydrolysis solution may be 40% by mass or less, or 20% by mass or less. Preferably, the hydrophilic solvent content in the hydrolysis solution is 10% by mass or more, and more preferably 15% by mass or more. Within this range, the miscibility between the silane compound and water can be further promoted, resulting in efficient hydrolysis of the silane compound. Note that the hydrolysis solution may not contain hydrophilic solvents other than those derived from the hydrolysis reaction. That is, it may contain only hydrophilic solvents that are compounds derived from the hydrolysis reaction.

[0096] In this embodiment, when a silane compound having an alkoxy group is used as the silane compound, hydrolysis occurs, resulting in the inclusion of alcohol compounds derived from the alkoxy group in the mixture. Since the hydrolysis reaction also proceeds with water adsorbed by metal oxide particles, it can occur in any of steps A to E. Therefore, in this case, unless there is a step to remove the alcohol compounds, the resulting dispersion will contain alcohol compounds. For this reason, a step to remove these alcohol compounds using an evaporator or the like may be appropriately provided.

[0097] In the hydrolysis process, after preparing the hydrolysate, it may be held at a predetermined temperature of any choice for a specified time. This can further accelerate the hydrolysis of the silane compound. In this process, the temperature of the hydrolysis solution is not particularly limited and can be arbitrarily selected and can be appropriately changed depending on the type of silane compound. For example, it is preferably 5°C to 65°C, more preferably 20°C to 65°C, and even more preferably 30°C to 60°C. If necessary, it may also be 40°C to 75°C or 50°C to 70°C.

[0098] Furthermore, the holding time at the above temperature is not particularly limited, but is preferably 10 minutes to 180 minutes, and more preferably 30 minutes to 120 minutes. If necessary, it may be 15 minutes to 60 minutes or 20 minutes to 40 minutes. Furthermore, the hydrolyzed solution may be stirred as appropriate during the retention of the hydrolyzed solution as described above.

[0099] (Process B (mixing process)) In the mixing step, the silane compound and metal oxide particles are mixed to obtain a mixture. In addition to the silane compound and metal oxide particles, water or a catalyst may also be mixed in the mixing step. If a hydrolyzed solution has been obtained by the hydrolysis step described above, the mixture can be obtained by mixing the hydrolyzed solution with the metal oxide particles.

[0100] The mixing is carried out such that the content of metal oxide particles in the mixture is 10% by mass or more and 49% by mass or less, and the total content of silane compounds and metal oxide particles is 65% by mass or more and 98% by mass or less.

[0101] Thus, in this embodiment, the total content of silane compounds and metal oxide particles in the mixture is very high. Furthermore, the organic solvents and dispersion media such as water, which were conventionally considered essential, are either not included in the mixture or are included in very small amounts compared to conventional methods. Alternatively, only small amounts of alcohol compounds, which are unavoidable due to hydrolysis, are included. Even in such cases, the dispersion process enables uniform dispersion of metal oxide particles in the mixture, and uniform adhesion (surface modification) of the silane compounds to the metal oxide particles is achieved.

[0102] To explain in more detail, when surface-modifying metal oxide particles with a silane compound in a liquid phase, it is common practice to mix not only the metal oxide particles and the silane compound but also the dispersion medium to obtain a mixture, and then disperse this mixture using a disperser. However, when metal oxide particles surface-modified in this way are mixed with methyl-based silicone resin, they cannot be sufficiently dispersed in the methyl-based silicone resin and tend to aggregate, resulting in problems such as cloudiness or turbidity in the methyl-based silicone resin. In such cases, the added metal oxide particles do not fully exhibit the desired performance.

[0103] Dispersion media are typically added to lower the viscosity of the mixture, uniformly disperse the metal oxide particles, and uniformly modify the surface of the metal oxide particles with the silane compound. Conventionally, it was believed that without a dispersion media, the viscosity of the dispersion would increase, resulting in insufficient adhesion of the silane compound to the surface of the metal oxide particles. Surprisingly, the inventors have discovered that by either not using or using only a small amount of the dispersion media that was previously considered essential, and by directly dispersing the metal oxide particles in a high concentration of silane compound, uniform dispersion of the metal oxide particles can be achieved in the resulting dispersion, and uniform modification of the metal oxide particles with the silane compound is possible.

[0104] Silane compounds are low molecular weight and have relatively low viscosity. Furthermore, due to the hydrolysis process described above, they exhibit good adhesion to metal oxide particles. For these reasons, silane compounds are extremely suitable for dispersing metal oxide particles in high-concentration surface-modifying materials.

[0105] If the total content of silane compounds and metal oxide particles is less than 65% by mass, the amount of other components, such as the dispersion medium, becomes too high, and as a result, the silane compounds cannot be sufficiently attached to the surface of the metal oxide particles in the dispersion step (step C) described later. As a result, many hydroxyl groups remain on the surface of the metal oxide particles, and when the resulting dispersion is mixed with a hydrophobic material, the metal oxide particles aggregate, causing turbidity in the hydrophobic material. The total content of silane compounds and metal oxide particles should be 65% by mass or more, but preferably 70% by mass or more, and more preferably 75% by mass or more. The total content of silane compounds and metal oxide particles may be 80% by mass or more, 85% by mass or more, 90% by mass or more, or 92% by mass or more, as needed.

[0106] In contrast, if the total content of the silane compound and metal oxide particles exceeds 98% by mass, the viscosity of the mixture becomes too high, making it impossible to adequately adhere the silane compound to the surface of the metal oxide particles in the dispersion step (step C) described later. The total content of the silane compound and metal oxide particles should be 98% by mass or less, preferably 97% by mass or less, and more preferably 95% by mass or less. The total content of the silane compound and metal oxide particles may be 90% by mass or less, 85% by mass or less, 80% by mass or less, or 75% by mass or less, as needed.

[0107] Furthermore, as mentioned above, the content of metal oxide particles in the mixture is between 10% by mass and 49% by mass. This range allows the amount of silane compound relative to the metal oxide particles to be within an appropriate range, enabling uniform adhesion of the silane compound to the surface of the metal oxide particles while suppressing an increase in the viscosity of the mixture.

[0108] On the other hand, if the content of metal oxide particles in the mixture is less than 10% by mass, the amount of silane compound becomes excessive relative to the metal oxide particles, and the excess silane compound in the resulting dispersion induces aggregation of the metal oxide particles. The content of metal oxide particles in the mixture is preferably 20% by mass or more, more preferably 23% by mass or more, even more preferably 26% by mass or more, and particularly preferably 30% by mass or more.

[0109] Furthermore, if the content of metal oxide particles exceeds 49% by mass, the amount of silane compound becomes insufficient relative to the metal oxide particles, and a sufficient amount of silane compound does not adhere to the metal oxide particles. Also, if the content of metal oxide particles becomes too high, the viscosity of the mixture becomes too high, and the metal oxide particles cannot be sufficiently dispersed in the dispersion step (step C) described later. The content of metal oxide particles in the mixture is preferably 45% by mass or less, and more preferably 40% by mass or less. The content of metal oxide particles in the mixture is even more preferably 38% by mass or less, and particularly preferably 36% by mass or less. The content of metal oxide particles in the mixture may also be 34% by mass or less.

[0110] The content of the silane compound relative to the content of metal oxide particles in the mixture is not particularly limited, but is preferably, for example, 100% to 800% by mass, more preferably 140% to 600% by mass, even more preferably 180% to 400% by mass, and particularly preferably 200% to 270% by mass, relative to the amount of metal oxide particles. This allows the amount of silane compound relative to the metal oxide particles to be within an appropriate range, and the silane compound to be uniformly attached to the surface of the metal oxide particles.

[0111] Furthermore, an organic solvent may be added to the mixture during the mixing process. By adding an organic solvent to the mixture, it becomes possible to control the reactivity of the surface modification material and thus control the degree to which the surface modification material adheres to the surface of the metal oxide particles. In addition, the viscosity of the mixture can be adjusted using the organic solvent.

[0112] Examples of such organic solvents include the hydrophobic and hydrophilic solvents listed above as dispersion media for the compositions of this embodiment. These organic solvents may be used individually or in combination of two or more.

[0113] The amount of organic solvent in the mixture is not particularly limited, as long as it satisfies the above-mentioned content requirements for metal oxide particles and silane compounds. It goes without saying that the mixture does not necessarily need to contain any organic solvent. The mixing time and temperature during the mixing process can be arbitrarily selected. For example, mixing may be performed at room temperature (25°C), and after combining the materials, stirring may be performed for 0 to 600 seconds.

[0114] (Process C (dispersion process)) In the dispersion step, metal oxide particles are dispersed in a mixed liquid to obtain a first dispersion containing dispersed metal oxide particles. In this embodiment, the metal oxide particles are dispersed in a hydrolyzed, high-concentration silane compound. Therefore, in the resulting first dispersion, the silane compound is relatively uniformly attached to the surface of the metal oxide particles, and the metal oxide particles are relatively uniformly dispersed.

[0115] The dispersion of metal oxide particles can be carried out by known dispersion methods, such as using a disperser. Suitable dispersers include, for example, bead mills, ball mills, homogenizers, dispersers, and stirrers. Step C is preferably a step in which only the mixture obtained in step B is dispersed.

[0116] In the dispersion process, it is preferable to apply only the minimum necessary energy, without applying excessive energy, so that the particle size of the metal oxide particles in the dispersion (dispersed particle size) becomes nearly uniform, thereby dispersing the metal oxide particles in the mixed liquid. The distribution time can be arbitrarily selected depending on the conditions, but for example, it may be 3 to 20 hours, preferably 4 to 18 hours, more preferably 6 to 16 hours, and even more preferably 8 to 14 hours. However, the distribution time is not limited to these. The dispersion temperature can be arbitrarily selected, but 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 ranges. Furthermore, one difference between the dispersion process C and the mixing process B is that the dispersion is carried out continuously over a certain period of time.

[0117] The scattering characteristics of the above-mentioned cured material at a wavelength of 450 nm and at a wavelength of 600 nm can be controlled relatively easily by adjusting the dispersion conditions. If the scattering component of the cured material at a wavelength of 450 nm is small, the dispersion time should be shortened. On the other hand, if the scattering component of the cured material at a wavelength of 450 nm is large, the dispersion time should be lengthened. If adjustment cannot be made by adjusting the dispersion time alone, the type and ratio of metal oxide particles and surface modification materials should be adjusted so that the scattering component of the cured material at a wavelength of 450 nm and at a wavelength of 600 nm are appropriate. In particular, adjustment by adjusting the refractive index of the metal oxide particles is preferable.

[0118] (Process D (Addition Process (First Addition Process))) In the addition step, a hydrophobic solvent is added to the first dispersion obtained in step C (dispersion step) to adjust the first dispersion to the desired solid content concentration. The first dispersion obtained in the dispersion process has a high solid content concentration. As a result, it has high viscosity and poor handling properties. However, simply adding a hydrophobic solvent to the obtained first dispersion to lower the solid content concentration results in the particles agglomerating due to the low hydrophobicity of the particle surface, making it impossible to obtain a uniform dispersion.

[0119] Therefore, the inventors investigated and found that by heating the obtained first dispersion and gradually adding a hydrophobic solvent, the dispersion can be adjusted to have a low solid content. Performing this procedure yields excellent results.

[0120] The mechanism described above is presumed to be as follows: By heating the first dispersion, polymerization of the silane compound attached to the metal oxide particles proceeds, improving the hydrophobicity of the particle surface. However, if the polymerization reaction of the silane compound proceeds too far, the metal oxide particles will aggregate. Therefore, a hydrophobic solvent is gradually added to the first dispersion while the polymerization reaction is in progress. By performing this addition, the surface is gradually made hydrophobic while suppressing excessive polymerization, and the hydrophobic solvent can be gradually mixed in.

[0121] In other words, a hydrophobic solvent is added in an amount that does not cause the metal oxide particles to aggregate, and the polymerization reaction of the silane compound is allowed to proceed to a degree that makes it miscible with the added amount of hydrophobic solvent. This makes it possible to obtain a dispersion with the desired solid content concentration.

[0122] As described above, the hydrophobic solvent should be added gradually so as not to cause the metal oxide particles to aggregate. Therefore, the first dispersion obtained in the above dispersion step may be heated before adding the hydrophobic solvent, or the first dispersion may be heated after adding the hydrophobic solvent, or the heating of the first dispersion and the addition of the hydrophobic solvent may be performed simultaneously. In other words, to explain more specifically, the addition step may be step d1 in which the hydrophobic solvent is added at a rate that does not cause the metal oxide particles to aggregate after heating the first dispersion; step d2 in which the hydrophobic solvent is added at a rate that does not cause the metal oxide particles to aggregate while heating the first dispersion; or step d3 in which the hydrophobic solvent is added at a rate that does not cause the metal oxide particles to aggregate, and then the first dispersion is heated.

[0123] In step d1, when adding the metal oxide particles, the heating of the dispersion may be continued or stopped. The temperature of the dispersion may be constant or it may change. It is preferable to maintain a constant temperature of the dispersion. In step d2, when adding the metal oxide particles, the temperature of the dispersion may be constant or it may change. The hydrophobic solvent mentioned above may be added continuously or intermittently in two or more separate additions. When adding intermittently, there is no limit to the number of additions; for example, it can be added in 2 to 6 additions or 3 to 5 additions. When adding the hydrophobic solvent in multiple additions, the amount of the solvent may be the same or varied.

[0124] The rate at which metal oxide particles do not aggregate is not particularly limited. The rate and proportion of hydrophobic solvent addition can be arbitrarily selected. For example, the hydrophobic solvent can be added continuously at a rate such that the solid content concentration decreases by 3% to 20% by mass per hour. In other words, after continuously adding the hydrophobic solvent for one hour, the difference in solid content concentration in the dispersion before and after addition may be in the range of 3% to 20% by mass. The amount of hydrophobic solvent added can be appropriately adjusted so that the amount of hydrophobic solvent added is increased when the heating temperature is high, and decreased when the heating temperature is low.

[0125] As mentioned above, the rate and rate of addition of the hydrophobic solvent can be arbitrarily selected. For example, the hydrophobic solvent can be added in stages every 30 minutes, every hour, or every 2 hours, so that the solid content concentration decreases within the range of 3% to 20% by mass. The amount of hydrophobic solvent added at one time should be increased when the heating temperature is high, and decreased when the heating temperature is low, so the amount of hydrophobic solvent added at one time should be adjusted as appropriate. In this case, the addition time and number of additions of the hydrophobic solvent may also be preferably adjusted.

[0126] The heating temperature is not particularly limited as long as it is within the temperature at which the polymerization reaction of the silane compound proceeds. For example, the heating temperature is preferably 35°C to 80°C. The heating temperature may also be 40°C to 75°C, 45°C to 70°C, or 50°C to 65°C. By heating to 35°C or higher, the polymerization reaction of the silane compound can be allowed to proceed. On the other hand, by heating to 80°C or lower, the aggregation of metal oxide particles due to the rapid reaction of the silane compound can be suppressed.

[0127] The heating time should be adjusted as needed until the solid content concentration is complete. Preferably, the heating time is between 4 and 12 hours. A heating time of 4 hours or more allows the polymerization reaction of the silane compound to proceed, enabling mixing with the hydrophobic solvent. On the other hand, a heating time of 12 hours or less suppresses the aggregation of metal oxide particles due to excessive polymerization of the silane compound.

[0128] The hydrophobic solvent is not particularly limited as long as it is compatible with the material to be mixed with the dispersion of this embodiment. Examples of hydrophobic solvents include aromatics, saturated hydrocarbons, and unsaturated hydrocarbons. These hydrophobic solvents may be used individually or in combination of two or more. Among these, aromatics, and especially aromatic hydrocarbons, are preferred. Aromatics have excellent compatibility with methyl-based silicone resins, which contributes to improving the viscosity properties of the resulting composition and the quality (transparency, shape, etc.) of the formed sealing member.

[0129] Examples of 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, and 4-ethyltoluene. These aromatic hydrocarbons may be used individually or in combination of two or more.

[0130] Among these, at least one aromatic hydrocarbon selected from the group consisting of toluene, o-xylene, m-xylene, p-xylene, and benzene is particularly preferred, from the viewpoint of the stability of the dispersion and ease of handling in the removal of the dispersion medium during the production of the composition described later.

[0131] The content of the hydrophobic solvent in the final dispersion can be adjusted as appropriate to achieve the desired solid content concentration. The hydrophobic solvent content is preferably, for example, 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and even more preferably 60% by mass or more and 80% by mass or less. The first addition step yields a second dispersion adjusted to the desired solid content concentration. Using the second dispersion improves the handling of the dispersion in the following steps.

[0132] (Process F (removal process)) In this embodiment, a step F may be provided between step D and step E to remove the alcohol produced by hydrolysis. It is presumed that the production efficiency of the process described below will improve by implementing a removal process. The removal method is not particularly limited, but for example, an evaporator can be used. The removal process may be carried out until the alcohol is completely removed, or about 5% by mass may remain.

[0133] (Process E (Second Addition Process)) Next, the metal oxide particles are treated with a silicone compound to obtain a third dispersion. As described above, in the dispersion step, the silane compound adheres relatively uniformly to the surface of the metal oxide particles. Therefore, the silicone compound can adhere relatively uniformly to the surface of the metal oxide particles via the silane compound.

[0134] In the second addition step, the second dispersion and the silicone compound are first mixed to obtain a treatment solution. The treatment solution may then be held at a constant temperature for a predetermined time. This can further promote the adhesion of the silicone compound to the metal oxide particles.

[0135] Examples of silicone compounds include those mentioned above. These silicone compounds may be used individually or in combination of two or more.

[0136] The silicone compound can be mixed with the second dispersion such that the content of the silicone compound in the third dispersion is, for example, preferably 50% to 500% by mass, more preferably 80% to 400% by mass, and even more preferably 100% to 300% by mass, relative to the metal oxide particles. This allows a sufficient amount of the silicone compound to adhere to the surface of the metal oxide particles, improving the dispersion stability of the metal oxide particles and improving their dispersibility in the methyl-based silicone resin. Furthermore, the amount of free silicone compound can be reduced, suppressing unintended aggregation of metal oxide particles in the methyl-based silicone resin.

[0137] In the second addition step, the holding temperature is not particularly limited and can be appropriately changed depending on the type of silicone compound, but it is preferably 40°C to 130°C, and more preferably 50°C to 120°C.

[0138] Furthermore, the holding time is not particularly limited, but is preferably, for example, 1 hour or more and 24 hours or less, and more preferably 2 hours or more and 20 hours or less. During the above holding process, the second dispersion may be stirred as appropriate.

[0139] Furthermore, in the second addition step, the silicone compound may be treated multiple times. For example, by using different types of silicone compounds and treating the material with the silicone compound multiple times, it becomes easier to control the surface state of the metal oxide particles according to the type of methyl-based silicone resin. Furthermore, in the second addition step, the solid content concentration may be measured after treatment with the silicone compound, and a hydrophobic solvent may be added to achieve the desired solid content concentration. Lowering the solid content concentration facilitates mixing with the resin components described later.

[0140] As described above, a third dispersion can be obtained by treating metal oxide particles with a silicone compound.

[0141] The dispersion produced using the above manufacturing method has uniformly dispersed metal oxide particles, and the surfaces of the metal oxide particles are uniformly and sufficiently modified with the silane compound and silicone compound. These modified metal oxide particles, with a refractive index of 1.70 to 2.00, exhibit excellent affinity for methyl-based silicone resins and can be dispersed relatively uniformly in the methyl-based silicone resin at a size that provides the desired scattering characteristics. Therefore, even when metal oxide particles are dispersed in a methyl-based silicone resin, the brightness of the light-emitting device can be improved when used as a sealing member.

[0142] Furthermore, the dispersion in this embodiment may contain, as necessary, other components besides those mentioned above, such as general additives like dispersants, dispersion aids, antioxidants, flow regulators, thickeners, pH adjusters, and preservatives. These may be added at any step as needed.

[0143] (composition) The composition of this embodiment is a mixture of the dispersion described above and a resin component. Therefore, the composition of this embodiment includes, in addition to metal oxide particles with a refractive index of 1.70 to 2.00 that are surface-modified with the silane compound and silicone compound described above, a resin component, i.e., at least one of a resin and its precursor.

[0144] The composition of this embodiment is cured as described later and used as a sealing member for a light-emitting element. By containing metal oxide particles that contribute to the improvement of refractive index and transparency as described above, the composition of this embodiment can improve the brightness of the light emitted by the light-emitting device when used as a sealing member.

[0145] Furthermore, the composition of this embodiment contains metal oxide particles with a refractive index of 1.70 to 2.00, which are surface-modified with the silane compound and silicone compound described above. Therefore, even when a methyl-based silicone resin is included as a resin component, excessive aggregation of the metal oxide particles is suppressed, and a decrease in transparency is suppressed. For this reason, when the composition of this embodiment is used as a sealing member, the brightness of the light emitted by the light-emitting device can be improved.

[0146] The content of metal oxide particles in the composition of this embodiment is not particularly limited as long as the amount is such that the scattering content of the cured product at a wavelength of 450 nm and the scattering content of the cured product at a wavelength of 600 nm are at desired values. For example, the content of the surface-modified metal oxide particles is preferably 2% by mass or more and 11% by mass or less, and more preferably 3% by mass or more and 10% by mass or less, relative to the total content of the surface-modified metal oxide particles and the resin component.

[0147] Furthermore, the content of surface-modifying materials such as silane compounds and silicone compounds in the composition of this embodiment can correspond to the content in the dispersion of this embodiment.

[0148] The average dispersed particle diameter of the surface-modified metal oxide particles in the composition of this embodiment is not particularly limited as long as the desired scattering characteristics are obtained. For example, it may be 30 nm to 1000 nm, 50 nm to 800 nm, or 60 nm to 700 nm. Furthermore, the average dispersed particle diameter of the surface-modified metal oxide particles is not particularly limited, as long as the particle diameter when cured as a sealing material is between 60 nm and 1000 nm. Note that the average dispersed particle diameter when the composition is cured refers to the secondary particle diameter (aggregated particle diameter) when the metal oxide particles are aggregated, i.e., when secondary particles are formed. The aggregation state of surface-modified metal oxide particles in the cured product varies depending on the combination of metal oxide particles, surface modification materials, resin components, and phosphor particles, as well as the curing conditions of the composition. Therefore, the average dispersed particle size of the metal oxide particles in the composition should be adjusted while checking the scattering characteristics at wavelengths of 450 nm and 600 nm after curing. One method for adjusting the average dispersed particle size of metal oxide particles in the composition is to adjust the average dispersed particle size of metal oxide particles in the dispersion. The average dispersed particle size of surface-modified metal oxide particles in a composition can be measured, for example, using a particle size distribution device.

[0149] (Resin components) The resin component is the main component in the composition of this embodiment. When the composition of this embodiment is used as a sealing material, the resin component hardens and seals the light-emitting element. As a result, it prevents deterioration factors from the external environment, such as moisture and oxygen, from reaching the light-emitting element. Furthermore, in this embodiment, the cured product obtained from the resin component is basically transparent and can transmit light emitted from the light-emitting element.

[0150] Such resin components are not particularly limited as long as they can be used as sealing materials. For example, silicone resins, epoxy resins, and other resins may be used individually or in combination of two or more. As for silicone resins, phenyl-based silicone resins and methyl-based silicone resins can be used. From the viewpoint of durability, methyl-based silicone resins are particularly preferred.

[0151] The above-mentioned methyl-based silicone resin may, for example, mean one in which the main skeleton has siloxane bonds in which silicon and oxygen are alternately bonded, and a large proportion of the functional groups bonded to the Si atoms, for example, 60% or more, preferably 80% or more, are methyl groups. However, the above-mentioned methyl-based silicone resin is not limited to this example. Examples of methyl-based silicone resins that can be used include dimethyl silicone resin and methylphenyl silicone resin.

[0152] The content of methyl-based silicone resin in the resin component can be adjusted according to the desired properties and is not particularly limited. For example, it may be 100% by mass, 20% to 80% by mass, 30% to 70% by mass, or 40% to 60% by mass. Conventionally, when metal oxide particles are included in methyl-based silicone resin, the metal oxide particles aggregate, reducing transparency and failing to sufficiently improve the refractive index. Furthermore, even when metal oxide particles are dispersed in methyl-based silicone resin, it is difficult to completely suppress the occurrence of excessive aggregation of metal oxide particles. In contrast to these, the composition of this embodiment contains metal oxide particles with a refractive index of 1.70 to 2.00, which are surface-modified with the silane compound and silicone compound described above. Therefore, even when such a large amount of methyl-based silicone resin is included as a resin component, aggregation of metal oxide particles is suppressed, and even if some aggregation occurs, the reduction in transparency is suppressed because the refractive index of the metal oxide particles is 1.70 to 2.00. Furthermore, since methyl-based silicone resin can be used, the durability of the sealing member formed using the composition is improved.

[0153] The structure of the resin component may be a two-dimensional chain structure, a three-dimensional network structure, or a cage-like structure. The resin component only needs to be in a cured polymer state when used as a sealing material. In the composition, the resin component may be in its uncured state, i.e., a precursor. Therefore, the resin component present in the composition may be, for example, a monomer, an oligomer, or a polymer.

[0154] The resin component may be of the addition reaction type, the condensation reaction type, or the radical polymerization reaction type. The viscosity of the resin component at 25°C, measured in accordance with JIS Z 8803:2011, is preferably, for example, 10 mPa·s or more and 100,000 mPa·s or less, more preferably 100 mPa·s or more and 10,000 mPa·s or less, and even more preferably 1,000 mPa·s or more and 7,000 mPa·s or less.

[0155] Furthermore, the content of the resin component in the composition of this embodiment may be the remainder of the other components, but it is preferably 10% by mass or more and 98% by mass or less, and more preferably 15% by mass or more and 97% by mass or less. The content of the resin component may be 30% by mass or more, 50% by mass or more, or 60% by mass or more. The content of the resin component may be 90% by mass or less, 80% by mass or less, or 70% by mass or less.

[0156] The composition of this embodiment may contain a dispersion medium derived from the dispersion according to this embodiment, or it may be removed. That is, the dispersion medium derived from the dispersion may be completely removed. The dispersion medium may remain in the composition in amounts of 1% by mass or more and 10% by mass or less, or in amounts of 2% by mass or more and 5% by mass or less.

[0157] Furthermore, the composition of this embodiment may contain phosphor particles to the extent that it does not hinder the objectives of the present invention. Phosphor particles absorb light of a specific wavelength emitted from a light-emitting element and emit light of a predetermined wavelength. In other words, phosphor particles enable the conversion of the wavelength of light and, consequently, the adjustment of the color tone.

[0158] The phosphor particles are not particularly limited and can be arbitrarily selected as long as they can be used in the light-emitting device described later, and can be selected and used as appropriate so that the light-emitting color of the device becomes the desired color. The amount of phosphor particles in the composition of this embodiment can be adjusted as appropriate to obtain the desired brightness.

[0159] Furthermore, the composition of this embodiment may contain commonly used additives such as preservatives, polymerization initiators, polymerization inhibitors, curing catalysts, and light diffusing agents, to the extent that they do not hinder the objectives of the present invention. It is preferable to use silica particles with an average particle size of 1 μm to 30 μm as the light diffusing agent.

[0160] The composition of this embodiment can be produced by mixing the dispersion of this embodiment with the resin component. After mixing, if necessary, the dispersion medium contained in the dispersion may be removed using an evaporator or the like.

[0161] The composition of this embodiment contains metal oxide particles with a refractive index of 1.70 to 2.00, which are surface-modified with the silane compound and silicone compound described above. As a result, even when a methyl-based silicone resin is included as a resin component, aggregation of the metal oxide particles is suppressed, and even if aggregation occurs, a decrease in transparency is suppressed. Therefore, a sealing member that improves the brightness of light from a light-emitting device can be formed using the composition of this embodiment.

[0162] According to the composition of this embodiment, the metal oxide particles, which are densely surface-modified with the surface-modifying material, are dispersed in the resin component such that the scattering components at a wavelength of 450 nm and 600 nm of the cured product are at desired values. Therefore, if the composition of this embodiment is cured and used as a sealing member for a light-emitting device, the brightness of the light-emitting device can be improved.

[0163] (Method of manufacturing the composition) The method for producing the composition of this embodiment is not particularly limited as long as the dispersion obtained in the above step can be mixed with the resin component. Furthermore, a step may be provided to remove the hydrophobic solvent from the obtained composition using an evaporator or the like. Furthermore, materials commonly found in sealing materials, such as phosphor particles, may be appropriately mixed in.

[0164] (Sealing member) The sealing member of this embodiment is a cured product of the composition of this embodiment. The sealing member of this embodiment is typically used as a sealing member or as part thereof, placed on a light-emitting element. The thickness and shape of the sealing member in this embodiment can be adjusted as appropriate according to the desired application and characteristics, and are not particularly limited.

[0165] The sealing member of this embodiment can be manufactured by curing the composition of this embodiment as described above. The curing method of the composition can be selected according to the properties of the resin component in the composition of this embodiment. Examples of curing methods for the composition include thermosetting and electron beam curing. More specifically, the sealing member of this embodiment can be obtained by curing the resin component in the composition of this embodiment by an addition reaction or polymerization reaction.

[0166] The dispersed particle diameter of the surface-modified metal oxide particles in the sealing member is not particularly limited as long as the scattering components of the cured material at a wavelength of 450 nm and at a wavelength of 600 nm are at desired values. The dispersed particle diameter of the surface-modified metal oxide particles in the sealing member may be, for example, 30 nm to 1000 nm, 40 nm to 900 nm, 50 nm to 800 nm, or 60 nm to 700 nm. Here, the dispersed particle diameter of the surface-modified metal oxide particles refers to the secondary particle diameter (aggregated particle diameter) when the particles are aggregated. The particle size of surface-modified metal oxide particles dispersed in the sealing member can be measured by observing a sample of the cured material cut into thin flakes using an electron microscope. However, since it is difficult to observe all surface-modified metal oxide particles in the sealing member, it is difficult to uniquely define the particle size of surface-modified metal oxide particles in the sealing member. Furthermore, even if the particle size is similar, the light transmittance will differ if the degree of aggregation between particles is different. Therefore, it is difficult to accurately measure the particle size of surface-modified metal oxide particles dispersed in the sealing member. For this reason, it is difficult to specify the characteristics of the sealing member of this embodiment based on the particle size of the surface-modified metal oxide particles dispersed.

[0167] Since the sealing member of this embodiment is a cured product of the composition of this embodiment, it has excellent light scattering properties and transparency. Therefore, according to this embodiment, a sealing member that improves the brightness of light from a light-emitting device can be obtained.

[0168] (Light-emitting device) The light-emitting device of this embodiment comprises the sealing member described above and a light-emitting element sealed in the sealing member.

[0169] Examples of light-emitting elements include light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs). In particular, the encapsulating member of this embodiment is suitable for encapsulating light-emitting diodes. The light-emitting device of this embodiment is preferably a white LED light-emitting device using a blue LED chip.

[0170] The following describes the light-emitting device of this embodiment, using an example where 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. Figures 1 to 4 are schematic diagrams (cross-sectional views) showing examples of the light-emitting device of this embodiment. Note that the dimensions of each component in the figures are exaggerated for ease of explanation and do not represent actual dimensions or ratios between components. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numeral to avoid redundant explanations.

[0171] The light-emitting device (LED package) 1A shown in Figure 1 comprises a substrate 2 having a recess 21, a light-emitting element (LED chip) 3 positioned on the bottom surface of the recess 21 of the substrate 2, and a sealing member 4A that seals the light-emitting element 3 in the recess 21. The sealing member 4A is composed of the sealing member of this embodiment described above. Therefore, metal oxide particles derived from the composition of this embodiment described above are dispersed in the sealing member 4A, and as a result, the light extraction efficiency in the light-emitting device 1A is improved. In addition, phosphor particles 5 are dispersed in the sealing member 4A. The phosphor particles 5 convert at least a portion of the wavelength of the light emitted from the light-emitting element 3.

[0172] The light-emitting device 1B shown in Figure 2 differs from the light-emitting device 1A in that the sealing member 4B has two layers. That is, the sealing member 4B has a first layer 41B that directly covers the light-emitting element 3 and a second layer 43B that covers the first layer 41B. Both the first layer 41B and the second layer 43B are sealing members according to this embodiment. Phosphor particles 5 are dispersed in the first layer 41B. On the other hand, the second layer 43B does not contain phosphor particles 5. The light-emitting device 1B has improved light brightness because metal oxide particles derived from the composition of this embodiment described above are dispersed in the first layer 41B and the second layer 43B that constitute the sealing member 4B.

[0173] The light-emitting device 1C shown in Figure 3 also differs from the light-emitting device 1A in that the configuration of the sealing member 4C is different from that of the sealing member 4A. The sealing member 4C has a first layer 41C that directly covers the light-emitting element 3 and a second layer 43C that covers the first layer 41C. The first layer 41C is not the sealing member of this embodiment, but a resin sealing member that does not contain the metal oxide particles described above, and is made of a resin that can be used for sealing members. Also, phosphor particles 5 are dispersed in the first layer 41C. On the other hand, the second layer 43C is the sealing member of this embodiment. In the light-emitting device 1C, the light extraction efficiency is improved because the metal oxide particles derived from the composition of this embodiment described above are dispersed in the second layer 43C that constitutes the sealing member 4C.

[0174] In the light-emitting device 1D shown in Figure 4, the sealing member 4D has a first layer 41D that directly covers the light-emitting element 3, a second layer 43D that covers the first layer 41D, and a third layer 45D that further covers the second layer 43D. The first layer 41D and the second layer 43D are not the sealing members of this embodiment, but rather resin sealing members that do not contain the metal oxide particles described above, and are made of resins that can be used for sealing members. Furthermore, phosphor particles 5 are dispersed within the second layer 43D. On the other hand, the third layer 45D is the sealing member of this embodiment. In the light-emitting device 1D, the brightness of the light is improved because the metal oxide particles derived from the composition of this embodiment described above are dispersed within the third layer 45D that constitutes the sealing member 4D.

[0175] It should be noted that the light-emitting device of this embodiment is not limited to the illustrated configuration. For example, the light-emitting device of this embodiment does not need to contain phosphor particles in the sealing member. Also, the sealing member of this embodiment can be located at any position within the sealing member.

[0176] As described above, the light-emitting device of this embodiment has improved light brightness because the light-emitting element is sealed by the sealing member of this embodiment.

[0177] Furthermore, in the light-emitting device of this embodiment, the light-emitting element is sealed with the composition of 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 sealing a light-emitting element using the composition of this embodiment. In the same aspect, the above manufacturing method may include a step of mixing the dispersion of this embodiment with a resin component to obtain the above composition.

[0178] The light-emitting element can be sealed, for example, by applying the composition of this embodiment onto the light-emitting element using a dispenser or the like, and then curing the composition.

[0179] (Lighting equipment, display devices) The light-emitting device of this embodiment, as described above, can be used, for example, in lighting fixtures and display devices. Therefore, in one aspect, the present invention relates to a lighting fixture or display device equipped with the light-emitting device of this embodiment. Examples of lighting fixtures include general lighting devices such as indoor and outdoor lights, and lighting for the switches of electronic devices such as mobile phones and office automation equipment. Because the lighting fixture of this embodiment is equipped with the light-emitting device of this embodiment, even when using the same light-emitting element, the emitted luminous flux is larger compared to conventional devices, making the surrounding environment brighter.

[0180] Examples of display devices include mobile phones, personal digital assistants (PDAs), electronic dictionaries, digital cameras, computers, televisions, and their peripheral devices. Because the display device of this embodiment is equipped with the light-emitting device of this embodiment, even when using the same light-emitting element, the emitted light flux is larger compared to conventional devices, and for example, it is possible to display a clearer and brighter image. [Examples]

[0181] The present invention will be described in more detail below with reference to examples and comparative examples. The examples described below are merely examples of the present invention and do not limit the invention.

[0182] [Example 1] (Preparation of dispersion) (i) Hydrolysis process 90.78 parts by mass of methyltriethoxysilane (trade name: KBE-13, manufactured by Shin-Etsu Chemical Co., Ltd.), 9.21 parts by mass of water, and 0.01 parts by mass of hydrochloric acid (1N) were prepared. These were added to a container and mixed to obtain a hydrolysis solution. Next, this hydrolysis solution was stirred at 60°C for 30 minutes to hydrolyze the methyltriethoxysilane and obtain a hydrolysis solution.

[0183] (ii) Mixing process (process B) A mixture was obtained by mixing 30 parts by mass of aluminum oxide (Al2O3) particles (manufactured by Sumitomo Chemical Co., Ltd.) with an average primary particle size of 9 nm with 70 parts by mass of the above hydrolysis solution.

[0184] (iii) Dispersion process (process C) This mixture was dispersed in a bead mill for 11 hours, after which the beads were removed to obtain the first dispersion.

[0185] (iv) First addition step (step D) The first dispersion obtained was heated at 60°C for 2 hours. Then, 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 was 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.

[0186] (v) Second addition step (step E) 88.1 parts by mass of a second dispersion, whose solid content concentration was adjusted to 20% by mass with toluene, and 11.9 parts by mass of methoxy group-containing phenyl silicone resin (product name: KR217, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed to obtain a treatment solution. This treatment solution was then heated at 110°C for 1 hour to obtain a dispersion (third dispersion). Next, toluene was mixed with the obtained dispersion to adjust the solid content concentration to 30% by mass, thus obtaining the dispersion of Example 1.

[0187] (Creation of a portrait) 3.8 g of the dispersion from Example 1 was mixed with 15.0 g of methylphenyl silicone (product name: KER-2500-B, manufactured by Shin-Etsu Chemical Co., Ltd.). Specifically, the total mass of the aluminum oxide particles and surface modification material was mixed with the methylphenyl silicone in a mass ratio of 7:93. Next, the toluene in this mixture was removed using an evaporator to obtain the composition of Example 1.

[0188] (Preparation of hardened material) The composition of Example 1 was filled into a 1 mm thick SUS container coated with Teflon® to a thickness of 1 mm. Then, the container was heated at 100°C for 2 hours, followed by heating at 150°C for 4 hours to obtain the cured product of Example 1. The thickness of the cured product removed from the container was 1 mm.

[0189] (light transmittance) The linear and integral transmittances of the cured material from Example 1, removed from its container, were measured at wavelengths of 450 nm and 600 nm using a spectrophotometer (JASCO Corporation, model number: V-770). Integral transmittance refers to the result measured using an integrating sphere. The scattering component was calculated from the difference between the integral and linear transmittances. The results are shown in Table 1.

[0190] (Electron microscope observation) Thin sections of the cured material from Example 1 were used as samples and observed using a field emission transmission electron microscope (product name: JEM-2100F, manufactured by JEOL Ltd.). The results are shown in Figures 5 and 6. From Figures 5 and 6, aggregated particles of approximately 400 nm were observed in the cured material from Example 1, but the aggregated particle size was approximately 200 nm to 600 nm.

[0191] (Fabrication of LED packages and evaluation of brightness) The brightness of the LED package before sealing with the composition of Example 1 was measured using a total luminous flux measurement system (manufactured by Otsuka Electronics Co., Ltd.) by applying a voltage of 3V and a current of 150mA to the LED package and taking a photometric measurement. In other words, the brightness A of the optical element itself was measured.

[0192] One part by mass of the composition from Example 1 and 0.38 parts by mass of phosphor particles (yttrium aluminum garnet: YAG) were mixed to form a composition (total amount of surface-modified aluminum oxide particles and resin: phosphor particles = 100:38), which was then filled into a lead frame to a thickness of 300 μm. The mixture was then held at room temperature for 3 hours. Next, the composition was slowly heat-cured to form the sealing member from Example 1, thereby fabricating the white LED package from Example 1.

[0193] For the white LED package obtained in Example 1, the brightness B was measured by applying a voltage of 3V and a current of 150mA to the LED package using a total luminous flux measurement system (manufactured by Otsuka Electronics Co., Ltd.) and taking a photometric measurement. The improvement rate of the brightness B (lm) of the white LED package in Example 1 compared to the brightness A (lm) of the optical element itself was calculated. The results are shown in Table 1.

[0194] [Example 2] (i) Hydrolysis process 90.78 parts by mass of methyltriethoxysilane (trade name: KBE-13, manufactured by Shin-Etsu Chemical Co., Ltd.), 9.21 parts by mass of water, and 0.01 parts by mass of hydrochloric acid (1N) were prepared. These were added to a container and mixed to obtain a hydrolysis solution. Next, this hydrolysis solution was stirred at 60°C for 30 minutes to hydrolyze the methyltriethoxysilane and obtain a hydrolysis solution. 47.92 parts by mass of propyltriethoxysilane (trade name: KBE-3033, manufactured by Shin-Etsu Chemical Co., Ltd.), 4.15 parts by mass of water, 0.02 parts by mass of hydrochloric acid (1N), and 47.92 parts by mass of methanol were prepared. These were added to a container and mixed to obtain a hydrolysate. This hydrolysate was stirred at 60°C for 1 hour to hydrolyze the propyltriethoxysilane and obtain a hydrolysate.

[0195] (ii) Mixing process (process B) A mixture was prepared by mixing 30 g of aluminum oxide (Al2O3) particles (manufactured by Sumitomo Chemical Co., Ltd.) with an average primary particle size of 9 nm, 77.1 g of hydrolyzed methyltriethoxysilane, and 32.6 g of hydrolyzed propyltriethoxysilane. Specifically, the aluminum oxide particles, methyltriethoxysilane, and propyltriethoxysilane were mixed in a mass ratio of 30:49:21.

[0196] Steps C, D, and E were carried out in the same manner as in Example 1, except that in the dispersion step (Step C) of Example 1, the mixture obtained in Step B of Example 2 was used instead of the mixture obtained in Step B of Example 1, to obtain the dispersion of Example 2 with a solid content concentration of 30% by mass.

[0197] The composition of Example 2 and the 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.

[0198] The light transmittance of the cured product of Example 2 was measured in the same manner as in Example 1. The results are shown in Table 1. In the same manner as in Example 1, a thin section of the cured material from Example 2 was observed using an electron microscope. As a result, aggregated particles of approximately 400 nm were observed in the cured material from Example 2, but the aggregated particle size ranged from approximately 200 nm to 600 nm. The cured material from Example 2 showed a greater proportion of aggregated particles with smaller diameters than the cured material from Example 1.

[0199] An LED package for Example 2 was fabricated in the same manner as in Example 1, except that the composition of Example 2 was used instead of the composition of Example 1. In the same manner as in Example 1, the brightness of the LED package before sealing with the composition of Example 2 and the LED package of Example 2 were measured, and the improvement rate of the brightness of the LED package was calculated. The results are shown in Table 1.

[0200] [Comparative Example 1] Comparative Example 1 was obtained in the same manner as in Example 1, except that, instead of using aluminum oxide particles with an average primary particle diameter of 9 nm, zirconium oxide particles with an average primary particle diameter of 12 nm were used, and the dispersion time in the bead mill was changed from 11 hours to 6 hours, with the solid content concentration adjusted to 30% by mass.

[0201] The composition of Comparative Example 1 was obtained in the same manner as in Example 1, except that the dispersion of Comparative Example 1 was used instead of the dispersion of Example 1 in the preparation of the composition of Example 1. Then, the composition of Comparative Example 1 was obtained by removing toluene in the same manner as in Example 1.

[0202] A cured product of Comparative Example 1 was obtained in the same manner as in Example 1, except that the composition of Comparative Example 1 was used instead of the composition of Example 1. The light transmittance was then observed in the same manner as in Example 1. The results are shown in Table 1. In the same manner as in Example 1, a thin section of the cured material from Comparative Example 1 was observed using an electron microscope. The results are shown in Figures 7 and 8. From Figures 7 and 8, it was confirmed that a large number of aggregated particles larger than 500 nm were formed in the cured material from Comparative Example 1.

[0203] The LED package for Comparative Example 1 was prepared in the same manner as in Example 1, except that the composition of Comparative Example 1 was used instead of the composition of Example 1. In the same manner as in Example 1, the brightness of the LED package before sealing with the composition of Comparative Example 1 and the LED package of Comparative Example 1 were measured, and the improvement rate of the brightness of the LED package was calculated. The results are shown in Table 1. The brightness of the LED package of Comparative Example 1 decreased compared to the LED package before sealing with the sealing member of Comparative Example 1.

[0204] [Comparative Example 2] Comparative Example 2 was obtained in the same manner as in Example 1, except that the dispersion treatment in the bead mill during the dispersion process was extended from 11 hours to 22 hours. The cured product of Comparative Example 2 was obtained in the same manner as in Example 1, except that the composition of Comparative Example 2 was used instead of the composition of Example 1, and the light transmittance was observed in the same manner as in Example 1. The results are shown in Table 1. In the same manner as in Example 1, a thin section of the cured material from Comparative Example 2 was observed using an electron microscope. As a result, similar to Example 1, the aggregated particle size was approximately 200 nm to 600 nm.

[0205] The LED package for Comparative Example 2 was prepared in the same manner as in Example 1, except that the composition of Comparative Example 2 was used instead of the composition of Example 1. In the same manner as in Example 1, the brightness of the LED package before sealing with the composition of Comparative Example 2 and the LED package of Comparative Example 2 were measured, and the improvement rate of the brightness of the LED package was calculated. The results are shown in Table 1. The brightness of the LED package of Comparative Example 2 decreased compared to the LED package before sealing with the sealing member of Comparative Example 2.

[0206] By comparing Examples 1 and 2 with Comparative Examples 1 and 2, it was confirmed that LED packages formed using a dispersion liquid in which surface-modified metal oxide particles, obtained by densely treating metal oxide particles with a refractive index of 1.70 to 2.00 with a methyl group-containing silane compound, are cured under predetermined conditions, and the scattering content at a wavelength of 450 nm is 17% to 38%, and the value obtained by dividing the scattering content at a wavelength of 450 nm by the scattering content at a wavelength of 600 nm is 1.25 or more, show improved brightness of the LED packages. Although the cured products of Example 1 and Comparative Example 2 could not be distinguished under a microscope, the brightness of the LED package did not improve due to scattering at a wavelength of 450 nm and an imbalance between scattering at 450 nm and 600 nm. These results suggest that by focusing on the scattering components at wavelengths of 450 nm and 600 nm and adjusting the dispersion conditions, it is possible to optimize the conditions for cured materials that improve the brightness of LED packages.

[0207] [Table 1]

[0208] Although preferred embodiments of the present invention have been described in detail above with reference to the attached drawings, the present invention is not limited to these examples. It is clear to any person with ordinary skill in the art to which the present invention belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these are also understood to fall within the technical scope of the present invention. [Explanation of symbols]

[0209] 1A, 1B, 1C, 1D Light-emitting devices 2 circuit boards 2a Top of the circuit board 2b Lower part of the circuit board 21 Recess 21a Bottom of the recess 3 Light-emitting elements 4A, 4B, 4C, 4D Sealing material 41B, 41C, 41D: First layer 43B, 43C, 43D: Second layer 45D Third Layer 5. Phosphorescent particles

Claims

1. A dispersion comprising metal oxide particles surface-modified with a surface-modifying material and a hydrophobic solvent, The metal oxide particles are aluminum oxide particles with a refractive index of 1.70 or more and 2.00 or less. The surface modification material comprises a silane compound and a silicone compound. The silane compound includes a methyl group-containing silane compound. When the aforementioned dispersion and methylphenyl silicone are mixed such that the mass ratio of the total mass of metal oxide particles and surface modification material to the mass of methylphenyl silicone is 7:93, and a cured product with a thickness of 1 mm is obtained, The scattering content of the cured product at a wavelength of 450 nm is 17% or more and 38% or less. A dispersion in which the value obtained by dividing the scattering component of the cured product at a wavelength of 450 nm by the scattering component of the cured product at a wavelength of 600 nm is 1.25 or more.

2. The dispersion according to claim 1, wherein the silane compound further comprises a hydrocarbon group-containing silane compound having 2 to 5 carbon atoms.

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

4. A sealing member which is a cured product of the composition described in claim 3.

5. A light-emitting device comprising a 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 described in claim 5.

7. A display device comprising the light-emitting device described in claim 5.

8. A method for producing a dispersion according to claim 2, Step B involves mixing a silane compound with metal oxide particles to obtain a mixed solution, Step C involves dispersing the metal oxide particles in the aforementioned mixture to obtain a first dispersion in which the metal oxide particles are dispersed. Step D involves adding a hydrophobic solvent to the first dispersion to obtain a second dispersion, The process includes step E, which involves adding a silicone compound to the second dispersion to obtain a third dispersion. The metal oxide particles are aluminum oxide particles with a refractive index of 1.70 or more and 2.00 or less. The silane compound includes a methyl group-containing silane compound and a hydrocarbon group-containing silane compound having 2 to 5 carbon atoms. In step B, the content of the metal oxide particles in the mixed liquid is 10% by mass or more and 49% by mass or less, and the total content of the silane compound and the metal oxide particles in the mixed liquid is 65% by mass or more and 98% by mass or less. A method for producing a dispersion, wherein step D is one of the following: step d1, after heating the first dispersion, adding the hydrophobic solvent at a rate that does not cause the metal oxide particles to aggregate; step d2, while heating the first dispersion, adding the hydrophobic solvent at a rate that does not cause the metal oxide particles to aggregate; or step d3, after adding the hydrophobic solvent at a rate that does not cause the metal oxide particles to aggregate.

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