阅读说明：本技术 无机粒子的表面修饰方法、分散液的制造方法及分散液 (Method for modifying surface of inorganic particle, method for producing dispersion, and dispersion ) 是由 伊藤智海 原田健司 大塚刚史 于 2020-03-24 设计创作，主要内容包括：本发明提供一种无机粒子的表面修饰方法,其具有：混合工序,至少将表面修饰材料和无机粒子进行混合而得到混合液；及分散工序,将所述无机粒子分散在所述混合液中,所述混合液中的所述无机粒子的含量为10质量％以上且49质量％以下,所述混合液中的所述表面修饰材料和所述无机粒子的总含量为65质量％以上且98质量％以下。(The present invention provides a method for modifying the surface of an inorganic particle, comprising: a mixing step of mixing at least the surface modification material and the inorganic particles to obtain a mixed solution; and a dispersion step of dispersing the inorganic particles in the mixed solution, wherein the content of the inorganic particles in the mixed solution is 10 mass% or more and 49 mass% or less, and the total content of the surface modification material and the inorganic particles in the mixed solution is 65 mass% or more and 98 mass% or less.)

1. A method for modifying the surface of an inorganic particle, comprising:

a mixing step of mixing at least the surface modification material and the inorganic particles to obtain a mixed solution; and

a dispersion step of dispersing the inorganic particles in the mixed solution,

the content of the inorganic particles in the mixed solution is 10 to 49 mass%,

the total content of the surface-modifying material and the inorganic particles in the mixed solution is 65 mass% or more and 98 mass% or less.

2. The method for modifying the surface of an inorganic particle according to claim 1,

a hydrolysis step of mixing at least the surface-modifying material and water to obtain a hydrolysate containing the hydrolyzed surface-modifying material, wherein the hydrolysis step is performed before the mixing step,

the mixing step is a step of mixing the hydrolysate containing the hydrolyzed surface modification material and the inorganic particles to obtain the mixed solution.

3. The method for modifying the surface of an inorganic particle according to claim 2,

the amount of water added to the hydrolysate is 0.5mol or more and 5mol or less with respect to 1mol of the surface modification material.

4. A method for producing a dispersion, comprising:

a mixing step of mixing the surface modification material and the inorganic particles to obtain a mixed solution; and

a dispersion step of dispersing the inorganic particles in the mixed solution to obtain a dispersion liquid in which the inorganic particles are dispersed,

the content of the inorganic particles in the mixed solution is 10 mass% or more and 49 mass% or less, and the total content of the surface modification material and the inorganic particles in the mixed solution is 65 mass% or more and 98 mass% or less.

5. A dispersion liquid comprising inorganic particles and at least one surface-modifying material at least partially attached to the inorganic particles,

the content of the inorganic particles is 10 to 49 mass%,

the total content of the surface-modifying material and the inorganic particles is 65 mass% or more and 98 mass% or less.

6. The dispersion liquid according to claim 5,

D90/D50 is 1.0 to 3.0 when the volume-based 90% particle diameter of the inorganic particles is D90 and the volume-based 50% particle diameter of the inorganic particles is D50.

7. The dispersion liquid according to claim 5 or 6,

the inorganic particles have an average primary particle diameter of 3nm to 200 nm.

Technical Field

The present invention relates to a method for modifying the surface of inorganic particles, a method for producing a dispersion, and a dispersion.

The present application claims priority based on the application's Japanese patent application No. 2019-066855, 3/29/2019, the contents of which are incorporated herein by reference.

Background

The inorganic particles can impart various properties such as a refractive index adjusting effect and a heat ray shielding function to a component, a member or a material. Therefore, the resin composition is used in various technical fields such as cosmetics, resin products, and optical components.

Inorganic particles are generally hydrophilic because they have hydroxyl groups on their surface when not modified. Therefore, when inorganic particles are added to a hydrophobic material, the surface of the inorganic particles is modified to be hydrophobic by a surface modifier such as a silane coupling agent.

For example, patent document 1 proposes a cosmetic pigment in which the surface of the pigment is coated with a specific silane coupling agent such as n-octyltriethoxysilane, and which has high water repellency when incorporated into a cosmetic, is not heavy but is wet to the touch, and has high adhesion to the skin.

Patent document 2 proposes an inorganic oxide transparent dispersion liquid containing inorganic oxide particles, the surfaces of which are modified with a surface modifier having one or more reactive functional groups, and the dispersion particle diameter of which is 1nm to 20 nm.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2001-181136

Patent document 2: international publication No. 2007/049573

Disclosure of Invention

Problems to be solved by the invention

However, when the inorganic particles are surface-modified with the surface-modifying material in a liquid phase, it is common to mix not only the inorganic particles and the surface-modifying material but also a dispersion medium to obtain a mixed liquid and disperse the mixed liquid with a dispersing machine. In addition, when inorganic particles surface-modified by such a method are mixed with a material having high hydrophobicity, the inorganic particles cannot be sufficiently dispersed in the material and aggregated, and as a result, there is a problem that turbidity such as white turbidity occurs in the material having high hydrophobicity.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a surface modification method for inorganic particles for obtaining inorganic particles that are inhibited from aggregating even when mixed with a material having high hydrophobicity and prevented from generating turbidity such as white turbidity, a method for producing a dispersion, and a dispersion.

Means for solving the problems

In order to solve the above problems, a first aspect of the present invention provides a method for modifying the surface of inorganic particles, comprising:

a mixing step of mixing at least the surface modification material and the inorganic particles to obtain a mixed solution; and

a dispersion step of dispersing the inorganic particles in the mixed solution,

the content of the inorganic particles in the mixed solution is 10 mass% or more and 49 mass% or less, and the total content of the surface modification material and the inorganic particles in the mixed solution is 65 mass% or more and 98 mass% or less.

The method of the first aspect of the present invention preferably includes the following features. The features described below may be individual features or two or more features may also be combined.

The method for modifying the surface of inorganic particles further comprises, prior to the mixing step, a hydrolysis step of mixing the surface-modifying material with water to obtain a hydrolysate containing the surface-modifying material after hydrolysis,

the mixing step may be a step of mixing the hydrolysate containing the hydrolyzed surface modification material and the inorganic particles to obtain the mixed solution.

The amount of water added to the hydrolysate may be 0.5mol or more and 5mol or less with respect to 1mol of the surface modification material.

In order to solve the above problem, a second aspect of the present invention provides a method for producing a dispersion, the method including:

a mixing step of mixing the surface modification material and the inorganic particles to obtain a mixed solution; and

a dispersion step of dispersing the inorganic particles in the mixed solution to obtain a dispersion liquid in which the inorganic particles are dispersed,

the content of the inorganic particles in the mixed solution is 10 mass% or more and 49 mass% or less, and the total content of the surface modification material and the inorganic particles in the mixed solution is 65 mass% or more and 98 mass% or less.

Further, in order to solve the above problems, a third aspect of the present invention provides a dispersion liquid containing inorganic particles and one or more surface-modifying materials at least a part of which is adhered to the inorganic particles,

the content of the inorganic particles is 10 to 49 mass%,

the total content of the surface-modifying material and the inorganic particles is 65 mass% or more and 98 mass% or less.

The dispersion liquid of the third embodiment of the present invention preferably includes the following features. The features described below may be individual features or two or more features may also be combined.

The D90/D50 ratio may be 1.0 to 3.0 when the volume-based 90% particle diameter of the inorganic particles is D90 and the volume-based 50% particle diameter of the inorganic particles is D50.

The inorganic particles may have an average primary particle diameter of 3nm to 200 nm.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a surface modification method for inorganic particles for obtaining inorganic particles that are inhibited from aggregating and prevented from generating turbidity such as white turbidity even when mixed with a material having high hydrophobicity, a method for producing a dispersion, and a dispersion.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail.

The present embodiment is described specifically for better understanding of the gist of the invention, and is not intended to limit the invention unless otherwise specified. The amount, number, type, ratio, configuration, and the like may be omitted, added, replaced, or modified without departing from the spirit of the present invention.

< 1. conception of the present inventors

First, before explaining the present invention in detail, the idea of the present inventors to complete the present invention will be explained.

As described above, when the inorganic particles are surface-modified with the surface-modifying material in a liquid phase, it is common to mix not only the inorganic particles and the surface-modifying material but also a dispersion medium to obtain a mixed solution, and then disperse the mixed solution using a dispersing machine. Here, when such surface-modified inorganic particles are mixed with a material having high hydrophobicity, they cannot be dispersed in the material sufficiently and aggregated, and as a result, there is a problem that turbidity such as white turbidity occurs in the material having high hydrophobicity. In this case, the added inorganic particles do not sufficiently exhibit the expected performance.

The dispersion medium is generally added for the purpose of uniformly dispersing the inorganic particles and uniformly modifying the surface of the inorganic particles with the surface modifying material. Conventionally, it has been considered that the surface-modifying material cannot be sufficiently adhered to the surface of the inorganic particles as a result of an increase in viscosity of the dispersion liquid without using a dispersion medium. The present inventors have surprisingly found that by directly dispersing inorganic particles in a high-concentration surface-modifying material without using or using only a small amount of such a dispersion medium, which has been conventionally considered essential, a uniform dispersion of the inorganic particles in the obtained dispersion liquid can be achieved, and at the same time, a uniform modification of the inorganic particles by the surface-modifying material can be performed.

The present inventors have also found that when the dispersion liquid obtained in this way is mixed with a material having high hydrophobicity, inorganic particles can be dispersed in the material without aggregation, and the generation of turbidity is suppressed, and have completed the present invention.

In addition, when a large amount of the dispersion medium is used in the dispersion, the reason why the inorganic particles are not dispersed in the material having high hydrophobicity when the dispersion liquid is mixed with the material having high hydrophobicity is not clear. However, as a result of the surface modification material in the vicinity of the inorganic particles becoming thin due to the presence of the dispersion medium, the reactivity of the surface modification material with respect to the inorganic particles is considered to be lowered, and a sufficient amount of the surface modification material is not attached to the inorganic particles. Further, when a large amount of a hydrophobic solvent is used as a dispersion medium in dispersion, it is considered that inorganic particles originally having hydroxyl groups on the surface are not sufficiently dispersed. Further, when a large amount of hydrophilic solvent is used as a dispersion medium in dispersion, the hydrophilic solvent contained in the dispersion liquid and the material having high hydrophobicity are not sufficiently miscible with each other.

Further, it is also conceivable to adhere the surface-modifying material to the surface of the inorganic particles in a dry manner by a henschel mixer, a spray dryer, or the like. However, in this case, the inorganic particles aggregate, and the surface-modifying material tends to adhere unevenly to the surfaces of the inorganic particles. Further, when the surface modification is performed in a dry manner, it is considered to be difficult to use a sufficient amount of the surface modification material. As a result, when the inorganic particles are mixed with a material having high hydrophobicity, the inorganic particles are not sufficiently dispersed in the material, and turbidity occurs.

< 2. method for surface modification of inorganic particles and method for producing dispersion

Next, preferred examples of the method for modifying the surface of the inorganic particles and the method for producing the dispersion according to the present embodiment will be described. Further, a method of modifying the surface of the inorganic particles may be considered as a method of producing the dispersion.

The method for modifying the surface of inorganic particles according to the present embodiment, which has been conceived by the present inventors through the above-described studies, includes a step (mixing step) of mixing a surface-modifying material and inorganic particles to obtain a mixed solution, and a step (dispersing step) of dispersing the inorganic particles in the mixed solution. The content of the inorganic particles in the mixed solution is 10 mass% or more and 49 mass% or less, and the total content of the surface modification material and the inorganic particles in the mixed solution is 65 mass% or more and 98 mass% or less.

The total content of the surface-modifying material and the inorganic particles does not contain an alcohol generated by hydrolysis of the surface-modifying material, which will be described later. That is, the total content of the surface-modifying material and the inorganic particles may be the total amount of the unhydrolyzed surface-modifying material, the hydrolyzed surface-modifying material and the inorganic particles. As a matter of course, the total content is a value including the content of the inorganic particles adhering to the surface modification material.

The method for producing a dispersion according to the present embodiment includes a step (mixing step) of mixing a surface modification material and inorganic particles to obtain a mixed solution, and a step (dispersing step) of dispersing the inorganic particles in the mixed solution to obtain a dispersion in which the inorganic particles are dispersed. The content of the inorganic particles in the mixed solution is 10 mass% or more and 49 mass% or less, and the total content of the surface modification material and the inorganic particles in the mixed solution is 65 mass% or more and 98 mass% or less.

In the present embodiment, it is preferable to include a step (hydrolysis step) of mixing the surface-modifying material and water to obtain a hydrolysate containing the hydrolyzed surface-modifying material, prior to the above-described steps.

Hereinafter, each step will be described in detail.

(2.1 hydrolysis step)

In this step, the surface-modifying material and water are mixed to obtain a hydrolysate containing the hydrolyzed surface-modifying material. By using the mixed liquid in which at least a part of the surface-modifying material is hydrolyzed in advance in this way, the surface-modifying material is easily attached to the inorganic particles in the dispersing step described later.

Such a surface-modifying material can be arbitrarily selected, and a surface-modifying material having a reactive functional group, for example, at least one functional group selected from the group consisting of an alkenyl group, an H — Si group, and an alkoxy group, is preferably used. In particular, the surface-modifying material having an alkoxy group is preferably used in the present embodiment because it can be hydrolyzed by reacting with water.

Examples of the alkenyl group include linear or branched alkenyl groups having 2 to 5 carbon atoms, and specific examples thereof include a vinyl group, a 2-propenyl group, and a prop-2-en-1-yl group.

Examples of the alkoxy group include linear or branched alkoxy groups having 1 to 5 carbon atoms, and specific examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, and a butoxy group.

Examples of the surface modification material having at least one functional group selected from the group consisting of an alkenyl group, an H — Si group, and an alkoxy group include, for example, the following silane compounds, silicone compounds, and fatty acids having a carbon-carbon unsaturated bond. One of them can be used alone or two or more of them can be used in combination.

Examples of the silane compound include silane compounds containing an alkyl group and an alkoxy group such as methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, isobutyltrimethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, etc., silane compounds containing an alkenyl group and an alkoxy group such as vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, etc., silane compounds containing an H-Si group and an alkoxy group such as diethoxymethylsilane, monoethoxydimethylsilane, diphenylmonomethoxysilane, diphenylmonoethoxysilane, etc., silane compounds containing another alkoxy group such as phenyltrimethoxysilane, etc., dimethylchlorosilane, and dimethylchlorosilane, And H-Si group-containing silane compounds such as methyldichlorosilane, diethylchlorosilane, ethyldichlorosilane, methylphenylchlorosilane, diphenylchlorosilane, phenyldichlorosilane, trimethoxysilane, dimethoxysilane, monomethoxysilane, and triethoxysilane.

Examples of the silicone compound include silicone compounds containing an H-Si group such as methylphenylsilicone, dimethylsilicone, methylhydrogensilicone, methylphenylsilicone, diphenylhydrosilicone, and the like, silicone compounds containing an alkoxy group such as alkoxyboth-terminal phenylsilicone, alkoxyboth-terminal methylphenylsilicone, alkoxymethylphenylsilicone, alkoxydimethylsilicone, alkoxytrimethylone-terminal (methyl one-terminal) dimethylsilicone, alkoxyphenylsilicone, and the like.

The silicone compound may be a monomer, an oligomer, or a resin (polymer). From the viewpoint of ease of surface modification, monomers or oligomers are preferably used as the silicone compound.

Examples of the fatty acid having a carbon-carbon unsaturated bond include methacrylic acid and acrylic acid.

These compounds may be used alone or in combination of two or more.

Among the above, the surface modification material is preferably a silane compound containing an alkyl group and an alkoxy group, or preferably contains the compound, from the viewpoint of low viscosity and easy dispersion of inorganic particles in a dispersion step described later.

The number of alkoxy groups in the silane compound containing an alkyl group and an alkoxy group is preferably 1 to 3, and the number of alkoxy groups is more preferably 3. The number of alkoxy groups may be 1 or 2, as required. The number of carbon atoms of the alkoxy group can be arbitrarily selected, and is preferably 1 to 5. The number of carbon atoms may be 1 or more and 3 or less, or 2 or more and 4 or less.

The number of alkyl groups in the silane compound containing an alkyl group and an alkoxy group is preferably 1 or more and 3 or less, and more preferably 1. The number of alkyl groups may be 2 or 3, as required. The number of carbon atoms of the alkyl group is preferably 1 or more and 5 or less, more preferably 1 or more and 3 or less, and still more preferably 1 or more and 2 or less. The total number of alkoxy groups and alkyl groups is preferably 2 or more and 4 or less, more preferably 4.

Examples of such silane compounds as the surface-modifying material include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, and ethyltripropoxysilane, and one or more selected from the group consisting of these compounds can be preferably contained.

The viscosity of the surface-modifying material at 25 ℃ can be selected as needed, and is preferably 50 mPas or less, for example.

When the viscosity of the surface-modifying material is 50mPa · s or less, the inorganic particles can be dispersed in the surface-modifying material without containing a large amount of a dispersion medium. The viscosity as used herein means a viscosity according to Z8803: 2011 measured viscosity.

The content of the surface modifying material in the hydrolysate is not particularly limited. The remaining part of the other components may be removed from the hydrolysate, and the content of the surface modification material in the hydrolysate is, for example, 60 mass% or more and 99 mass% or less, preferably 70 mass% or more and 97 mass% or less, and more preferably 80 mass% or more and 95 mass% or less.

In this step, the hydrolysate contains water. Water becomes the substrate for the hydrolysis reaction of the surface modifying material.

The content of water in the hydrolysate is not particularly limited and can be arbitrarily selected. For example, the content of water can be appropriately set corresponding to the amount of the surface modification material. For example, the amount of water added to the hydrolysate is preferably 0.5mol or more and 5mol or less, more preferably 0.6mol or more and 3mol or less, and further preferably 0.7mol or more and 2mol or less, based on 1mol of the surface modification material. This makes it possible to sufficiently progress the hydrolysis reaction of the surface-modifying material and more reliably prevent the occurrence of aggregation of the inorganic particles in the dispersion liquid produced from an excessive amount of water. The water content in the hydrolysate may be, for example, 1 mass% or more and 40 mass% or less, may be 3 mass% or more and 30 mass% or less, may be 5 mass% or more and 20 mass% or less, and may be 8 mass% or more and 13 mass% or less.

Alternatively, the content of water in the hydrolysate may be, for example, 1 mass% or more and 20 mass% or less, preferably 1 mass% or more and 15 mass% or less, and more preferably 1 mass% or more and 10 mass% or less.

Furthermore, a catalyst may be added to the hydrolysate. The hydrolysate can also contain only surface modification material, water and catalyst. As the catalyst, for example, an acid or a base can be used.

The acid catalyzes the hydrolysis reaction of the surface modification material in the hydrolysate and the mixed solution prepared from the hydrolysate. On the other hand, the base catalyzes a condensation reaction of the hydrolyzed surface-modifying material and functional groups on the surface of the inorganic particles, for example, with hydroxyl groups or silanol groups. By these reactions, the surface modification material is easily attached to the inorganic particles, and the dispersion stability of the inorganic particles is improved.

Here, the "acid" refers to an acid based on the definition of so-called bronsted-lowry, and herein refers to a substance that imparts a proton in a hydrolysis reaction of a surface modification material. The "base" is defined as a base based on the definition of so-called bronsted-lowry, and herein, means a substance that accepts protons in a hydrolysis reaction and a subsequent condensation reaction of the surface modification material.

The acid that can be used in the production method according to the present embodiment is not particularly limited as long as it can supply protons in the hydrolysis reaction of the surface modification material, and can be arbitrarily selected. Examples of the acid include inorganic acids such as hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, boric acid, and phosphoric acid, and organic acids such as acetic acid, citric acid, and formic acid. These acids can be used singly or in combination of two or more.

The base that can be used in the production method according to the present embodiment is not particularly limited as long as it can accept protons in the hydrolysis reaction or the subsequent condensation reaction of the surface modification material, and can be arbitrarily selected. Examples thereof include sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide, ammonia, and amines. These bases can be used singly or in combination of two or more.

Among the above, as the catalyst, an acid is preferably used. As the acid, from the viewpoint of acidity, an inorganic acid is preferable, and hydrochloric acid is more preferable.

The content of the catalyst in the hydrolysate is not particularly limited and can be arbitrarily selected. For example, the concentration may be 10ppm to 1000ppm, preferably 20ppm to 800ppm, and more preferably 30ppm to 600 ppm. This can sufficiently promote hydrolysis of the surface modification material and can suppress unintended side reactions of the surface modification material. Further, the concentration may be 0.1ppm to 100ppm, or 1ppm to 10ppm, as required. For example, when hydrochloric acid (1N) is used as the catalyst, the amount of hydrochloric acid may be 0.001 part by mass or more and 5 parts by mass or less, may be 0.001 part by mass or more and 3 parts by mass or less, may be 0.005 part by mass or more and 1 part by mass or less, and may be 0.005 part by mass or more and 0.1 part by mass or less, relative to 100 parts by mass of the hydrolysate.

The hydrolysate may contain a hydrophilic solvent as necessary. The hydrophilic solvent can promote the mixing of water and the surface modification material in the hydrolysate, and further promote the hydrolysis reaction of the surface modification material.

Examples of such a hydrophilic solvent include an alcohol-based solvent, a ketone-based solvent, and a nitrile-based solvent. One of them can be preferably used alone or two or more of them can be used in combination.

Examples of the alcohol solvent include branched or straight-chain alcohol compounds having 1 to 4 carbon atoms and ether condensates thereof. These solvents can be used alone or in combination of two or more. The alcohol compound contained in the alcohol solvent may be any of a primary alcohol, a secondary alcohol, and a tertiary alcohol. The alcohol compound contained in the alcohol solvent may be any of a monohydric alcohol, a dihydric alcohol, and a trihydric alcohol. More specifically, examples of the alcohol solvent include methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, methyl glycol, 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, glycerol, diethylene glycol, and 3-methoxy-1, 2-propanediol.

Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

Preferable examples of the nitrile solvent include acetonitrile.

Among the above, the hydrophilic solvent preferably contains an alcohol solvent from the viewpoint of having excellent affinity with both water and a hydrophobic solvent and promoting mixing of them. In this case, the number of carbon atoms of the alcohol compound constituting the alcohol solvent is preferably 1 to 3, more preferably 1 to 2. The hydrophilic solvent may be composed of only an alcohol solvent.

Among the above, methanol and ethanol are preferable. In particular, methanol can be preferably used because the effect of the alcohol solvent can be sufficiently exhibited.

The content of the hydrophilic solvent in the hydrolysate is not particularly limited, and may be, for example, 60 mass% or less, and preferably 50 mass% or less. With this range, the content of the surface-modifying material and water in the hydrolysate can be sufficiently increased. The content of the hydrophilic solvent may be 40% by mass or less, 20% by mass or less, 10% by mass or less, or 5% by mass or less. The content of the hydrophilic solvent in the hydrolysate may be, for example, 10 mass% or more, and preferably 15 mass% or more. In this range, the mixing of the surface modification material and water can be further promoted, and as a result, the hydrolysis reaction of the surface modification material can be efficiently performed. The hydrolysis liquid may not contain a hydrophilic solvent other than the compound derived from the hydrolysis reaction. That is, the solvent may contain only a hydrophilic solvent as a compound derived from the hydrolysis reaction.

In the present embodiment, when a compound having an alkoxy group, for example, a silane compound having an alkoxy group is used as the surface modification material, the alcohol compound derived from the alkoxy group is contained in the mixed solution due to hydrolysis thereof. Since the hydrolysis reaction proceeds also in the water adsorbed by the inorganic particles, the hydrolysis step, the mixing step, and the dispersing step can be performed. Therefore, in this case, the alcohol compound is contained in the final dispersion liquid unless the step of removing the alcohol compound is performed.

In this step, after the preparation of the hydrolysate, the hydrolysate may be kept at an arbitrarily selected constant temperature for a predetermined time. This can further promote hydrolysis of the surface modification material.

In this treatment, the temperature of the hydrolysate is not particularly limited, and can be arbitrarily selected and appropriately changed depending on the kind of the surface-modifying material. For example, 5 ℃ or more and 65 ℃ or less, more preferably 20 ℃ or more and 65 ℃ or less, and still more preferably 30 ℃ or more and 60 ℃ or less. If necessary, the temperature may be 40 ℃ to 75 ℃ inclusive, or 50 ℃ to 70 ℃ inclusive.

The holding time at the temperature is not particularly limited, and is, for example, 10 minutes to 180 minutes, preferably 30 minutes to 120 minutes. If necessary, the time may be 15 minutes to 60 minutes, or 20 minutes to 40 minutes.

In addition, the hydrolysate may be appropriately stirred while maintaining the above hydrolysate.

This step may be performed as needed, or may be omitted.

(2.2 mixing Process)

In this step, at least the surface-modifying material and the inorganic particles are mixed to obtain a mixed solution. In the case where a hydrolysate containing the surface modification material is obtained by the hydrolysis step, a mixed solution is obtained by mixing the hydrolysate with the inorganic particles. The hydrolysate can contain the above-mentioned compound or solvent in addition to the surface-modifying material. The mixed liquid is preferably composed only of the hydrolysate and the inorganic particles.

In this step, the mixture is mixed so that the content of the inorganic particles in the mixture is 10 mass% or more and 49 mass% or less and the total content of the surface-modifying material and the inorganic particles is 65 mass% or more and 98 mass% or less. The amount or ratio of each material may be adjusted in advance so as to satisfy the above content in the mixing step.

As described above, in the present embodiment, the total content of the surface modification material and the inorganic particles in the mixed liquid is very large, in the range of 65 mass% to 98 mass%. In addition, the dispersion medium such as an organic solvent and water, which has been conventionally considered essential, is not contained in the mixed liquid, or is mixed in an extremely small amount as compared with the conventional one. Or a degree that an alcohol compound is inevitably contained in a small amount due to hydrolysis. The present inventors have found that, even in this case, uniform dispersion of the inorganic particles can be achieved and uniform adhesion of the surface modification material to the inorganic particles (surface modification) can be achieved by performing the dispersion step in the mixed solution.

Here, the surface modification material "attached" to the inorganic particles means that the surface modification material is in contact with or bonded to the inorganic particles through an interaction therebetween. Examples of the contact include physical adsorption. Further, examples of the bonding include ionic bonding, hydrogen bonding, and covalent bonding.

On the other hand, when the total content of the surface-modifying material and the inorganic particles is less than 65 mass%, the components other than the two components, for example, the dispersion medium, becomes too large, and therefore the surface-modifying material tends to be insufficiently adhered to the surfaces of the inorganic particles in the dispersing step described later. As a result, a large amount of hydroxyl groups remain on the surface of the inorganic particles, and when the dispersion obtained by dispersion is mixed with a material having high hydrophobicity, the inorganic particles aggregate, and turbidity occurs in the material having high hydrophobicity. The total content of the surface-modifying material and the inorganic particles may be 65 mass% or more, preferably 70 mass% or more, and more preferably 75 mass% or more. If necessary, the content may be 80% by mass or more, 85% by mass or more, 90% by mass or more, or 92% by mass or more.

On the other hand, when the total content of the surface-modifying material and the inorganic particles exceeds 98 mass%, the viscosity of the mixed solution becomes too high, and the surface-modifying material does not tend to be sufficiently adhered to the surfaces of the inorganic particles in a dispersing step described later. The total content of the surface-modifying material and the inorganic particles may be 98 mass% or less, preferably 97 mass% or less, and more preferably 95 mass% or less. If necessary, the content may be 90% by mass or less, 85% by mass or less, 80% by mass or less, or 75% by mass or less.

As described above, the content of the inorganic particles in the mixed solution is 10 mass% or more and 49 mass% or less. With this range, the amount of the surface modification material relative to the inorganic particles can be set within an appropriate range, and the surface modification material can be uniformly adhered to the surface of the inorganic particles, and the increase in viscosity of the mixed liquid can be suppressed. The content of the surface modification material in the mixed solution may be 16 mass% or more and 88 mass% or less.

On the other hand, when the content of the inorganic particles in the mixed liquid is less than 10% by mass, the amount of the surface-modifying material is excessive relative to the amount of the inorganic particles, and the excessive surface-modifying material in the obtained dispersion liquid has a strong tendency to induce aggregation of the inorganic particles.

The content of the inorganic particles in the mixed solution is preferably 20% by mass or more, more preferably 23% by mass or more, still more preferably 26% by mass or more, and particularly preferably 30% by mass or more.

When the content of the inorganic particles exceeds 49 mass%, the amount of the surface-modifying material is insufficient relative to the inorganic particles, and a sufficient amount of the surface-modifying material is not adhered to the inorganic particles. Further, the content of the inorganic particles becomes too large, and as a result, the viscosity of the mixed liquid becomes too high, and the inorganic particles tend not to be sufficiently dispersed in a dispersing step described later. The content of the inorganic particles in the mixed liquid is preferably 45% by mass or less, more preferably 40% by mass or less, still more preferably 38% by mass or less, and particularly preferably 36% by mass or less. The content may be 34% by mass or less.

The ratio of the content of the surface modification material to the content of the inorganic particles in the mixed solution is not particularly limited, and is, for example, 100 mass% or more and 800 mass% or less, preferably 140 mass% or more and 600 mass% or less, more preferably 180 mass% or more and 400 mass% or less, and particularly preferably 200 mass% or more and 270 mass% or less with respect to 100 mass% of the amount of the inorganic particles. This makes it possible to set the amount of the surface modification material to the appropriate range, and to uniformly adhere the surface modification material to the surface of the inorganic particles.

The inorganic particles contained in the mixed solution according to the present embodiment are not particularly limited. In the present embodiment, as the inorganic particles, for example, particles containing a material selected from the group consisting of zirconium oxide particles, titanium oxide particles, silica particles, zinc oxide particles, iron oxide particles, copper oxide particles, tin oxide particles, cerium oxide particles, tantalum oxide particles, niobium oxide particles, tungsten oxide particles, europium oxide particles, yttrium oxide particles, molybdenum oxide particles, indium oxide particles, antimony oxide particles, germanium oxide particles, lead oxide particles, bismuth oxide particles, and hafnium oxide particles, and potassium titanate particles, barium titanate particles, strontium titanate particles, potassium niobate particles, lithium niobate particles, calcium tungstate particles, yttrium oxide stabilized zirconia particles, alumina stabilized zirconia particles, silica stabilized zirconia particles, calcium oxide stabilized zirconia particles, magnesium oxide stabilized zirconia particles, scandium oxide stabilized zirconia particles, and the like are preferably used, At least one or two or more kinds of inorganic oxide particles selected from the group consisting of hafnium oxide-stabilized zirconia particles, yttrium oxide-stabilized zirconia particles, cerium oxide-stabilized zirconia particles, indium oxide-stabilized zirconia particles, strontium-stabilized zirconia particles, samarium oxide-stabilized zirconia particles, gadolinium oxide-stabilized zirconia particles, antimony-added tin oxide particles, and indium-added tin oxide particles.

The mixing time or the mixing temperature in the mixing step can be arbitrarily selected, and for example, the mixing may be performed at room temperature, or the materials may be mixed together and then stirred for about 0 to 600 seconds.

The type of the inorganic particles can be appropriately selected depending on the use of the obtained dispersion. For example, when the inorganic particles in the obtained dispersion are used as a material for a sealing member of a light-emitting element, the mixed solution preferably contains at least one selected from the group consisting of zirconia particles, titania particles and silica particles from the viewpoint of improving transparency and compatibility (affinity) with a sealing resin (resin component). In addition, the refractive index of the inorganic particles is preferably 1.7 or more from the viewpoint of increasing the refractive index of the sealing member. Examples of such inorganic particles include inorganic oxide particles other than the silica particles. In the case of being used as a material of the sealing member, the inorganic particles are more preferably zirconia particles and/or titania particles, and particularly preferably zirconia particles.

The inorganic particles may be dispersed in the mixed solution as primary particles, or may be dispersed as secondary particles in which the primary particles are aggregated. Generally, the inorganic particles are dispersed as secondary particles in the mixed liquid.

The average primary particle size of the inorganic particles to be used can be arbitrarily selected, and is, for example, 3nm or more and 200nm or less, preferably 5nm or more and 170nm or less, and more preferably 10nm or more and 100nm or less. The average primary particle diameter of the inorganic particles may be 5 to 20nm, or 5 to 25nm, or 50 to 120nm, or 50 to 150nm, as required. When the average primary particle diameter is within the above range, the transparency of the dispersion is improved. When the resin composition is used as a material for a sealing member of a light emitting element, for example, an LED (light emitting diode), the luminance of the light emitting element (LED) can be improved.

The average primary particle diameter of the inorganic particles can be measured, for example, by observation with a transmission electron microscope. First, a transmission electron microscope image was obtained by observing a collodion film obtained by extracting inorganic particles from a dispersion liquid with a transmission electron microscope. Then, the inorganic particles in a predetermined number, for example, 100 transmission electron microscope images are selected. Then, the longest straight line amount (maximum major axis) of each of these inorganic particles is measured, and the measurement values are arithmetically averaged to obtain the average value.

Here, when the inorganic particles are aggregated, the aggregate particle diameter of the aggregate is not measured. The maximum major axis of a predetermined number of particles (primary particles) of the inorganic particles constituting the aggregate was measured as an average primary particle diameter.

In this step, an organic solvent may be further mixed in the mixed solution. By mixing the organic solvent, the reactivity of the surface modification material can be controlled, and the degree of adhesion of the surface modification material to the surface of the inorganic particle can be controlled. The viscosity of the mixed liquid can be adjusted by the organic solvent.

Examples of such an organic solvent include an alcohol-based solvent, a ketone-based solvent, an aromatic solvent, a saturated hydrocarbon-based solvent, and an unsaturated hydrocarbon-based solvent, and one of them may be used alone or two or more thereof may be used in combination.

In addition, when the surface modification material is hydrolyzed in the mixing step, a compound derived from the surface modification material, for example, an alcohol-based solvent is contained in the mixed solution.

The content of the organic solvent in the mixed solution is not particularly limited as long as the content of the inorganic particles and the surface-modifying material satisfies the above-mentioned contents. It is needless to say that the mixed solution may not contain an organic solvent.

In addition, other components than the above-described components, for example, a dispersant, a dispersion aid, an antioxidant, a flow control agent, a thickener, a pH adjuster, a preservative, and other common additives may be mixed in the mixed solution as necessary.

(2.3 dispersing step)

Next, the inorganic particles are dispersed in the mixed solution to obtain a dispersion liquid in which the inorganic particles are dispersed. The inorganic particles can be dispersed by a known dispersion method, for example, using a known dispersing machine. As the dispersing machine, for example, a bead mill, a ball mill, a homogenizer, a disperser, a stirrer, or the like is preferably used. The dispersing step is preferably a step of performing a dispersing treatment only on the mixture obtained in the mixing step.

Here, in this step, it is preferable to disperse the inorganic particles by applying the minimum required energy without applying excessive energy so that the particle diameters (dispersion particle diameters) of the inorganic particles in the dispersion are substantially uniform.

The dispersing time can be arbitrarily selected depending on the conditions, and for example, may be 6 to 18 hours, preferably 8 to 12 hours, and more preferably 10 to 11 hours. However, the present invention is not limited thereto.

The dispersion temperature can be arbitrarily selected, and for example, it may be 10 to 50 ℃, preferably 20 to 40 ℃, and more preferably 30 to 40 ℃. However, the present invention is not limited thereto.

The difference between the dispersing step and the mixing step may be that the dispersion is continuously performed for a fixed period of time.

This can provide a dispersion. In the dispersion liquid produced by the method according to the present embodiment, the inorganic particles are uniformly dispersed, and the surfaces of the inorganic particles are uniformly and sufficiently modified by the surface-modifying material. Then, when the highly hydrophobic material and the dispersion liquid are mixed, the inorganic particles can be uniformly dispersed in the highly hydrophobic material. As a result, turbidity, for example, white turbidity, of the material having high hydrophobicity is prevented. Therefore, the target function of the inorganic particles is exhibited with little influence on the color tone of the material having high hydrophobicity.

< 3. Dispersion liquid >

Next, the dispersion liquid according to the present embodiment will be described. The dispersion liquid according to the present embodiment contains inorganic particles and one or more surface-modifying materials at least a part of which is attached to the inorganic particles. The content of the inorganic particles is 10 to 49 mass%, and the total content of the surface-modifying material and the inorganic particles is 65 to 98 mass%.

The total content of the surface-modifying material and the inorganic particles can also be evaluated by the solid content. The solid content can be measured by the method described later.

In the present embodiment, the dispersion liquid is produced by the method for producing a dispersion liquid according to the present embodiment. Therefore, the inorganic particles are uniformly dispersed, and the surfaces of the inorganic particles are uniformly and sufficiently modified by the surface modifying material. When a material having high hydrophobicity is mixed with the obtained dispersion liquid, the inorganic particles can be uniformly dispersed in the material having high hydrophobicity, and the turbidity of the hydrophobic material can be prevented. As a result, the color tone of the material having high hydrophobicity is hardly affected, and the intended function of the inorganic particles is exhibited.

In addition, the dispersion liquid according to the present embodiment can obtain the above-described effects more remarkably in the case of inorganic particles that are difficult to disperse, for example, inorganic particles of fine particles.

The volume-based 50% particle diameter D50 of the inorganic particles in the obtained dispersion is not particularly limited, but is, for example, 30nm to 400nm, preferably 40nm to 300nm, and more preferably 50nm to 250 nm. If necessary, it may be 30nm to 80nm, 30nm to 100nm, 80nm to 180nm, or the like. In general, the particle diameter in the above-described range is likely to cause aggregation of the inorganic particles due to the high specific surface area. However, in the dispersion liquid according to the present embodiment, the surface modification material is uniformly and sufficiently attached to the inorganic particles. Therefore, the inorganic particles can be stably dispersed. When the dispersion liquid and the material having high hydrophobicity are mixed, aggregation of the inorganic particles is also suppressed, and the inorganic particles can be stably dispersed in the material having high hydrophobicity.

D90/D50 when the volume-based 90% particle diameter of the inorganic particles is D90 and the volume-based 50% particle diameter of the inorganic particles is D50 are not particularly limited, but are, for example, 1.0 to 3.0, preferably 1.0 to 2.5, and more preferably 1.0 to 2.3. If necessary, the content may be 1.4 to 2.3, 1.6 to 2.1, 1.8 to 2.0. D90/D50 is an index of the shape of the particle size distribution of the inorganic particles, and is one of the indexes of uniformity of the particle size of the inorganic particles. When D90/D50 is in the above range, the particle diameter of the inorganic particles in the dispersion becomes relatively uniform. In addition, the inorganic particles having such a uniform particle diameter in the dispersion liquid according to the present embodiment can be dispersed relatively stably and uniformly in the material having high hydrophobicity. Such a range of D90/D50 can be relatively easily achieved by the method for producing a dispersion according to the present embodiment.

The inorganic particle diameters D50 and D90 may be the particle diameters D50 and D90 when the cumulative percentage of the scattering intensity distribution obtained by the dynamic light scattering method is 50% and 90%, respectively. D10, D50 and D90 can be measured by a dynamic light scattering particle size distribution meter (for example, HORIBA, manufactured by Ltd., model: SZ-100 SP). The measurement can be carried out using a quartz cell having an optical path length of 10mm × 10mm, with respect to a dispersion liquid in which the solid content is adjusted to 5 mass% with an alcohol compound.

In the present specification, the term "solid component" refers to a residue obtained by removing a volatile component from a dispersion. For example, when 1.2g of the dispersion was placed in a magnetic crucible and heated at 100 ℃ for 1 hour on a hot plate, the components (inorganic particles, surface-modifying materials, etc.) remaining without volatilization could be made solid.

Further, regardless of whether the inorganic particles are dispersed in the form of primary particles or secondary particles, D50 and D90 of the inorganic particles are measured and calculated from the diameters of the inorganic particles in the dispersed state. In this embodiment, D50 and D90 of the inorganic particles may be measured as D50 and D90 of the inorganic particles to which the surface modifier is attached. In the dispersion, there may be inorganic particles to which the surface-modifying material is attached and inorganic particles to which the surface-modifying material is not attached. Therefore, the D50 and D90 of the inorganic particles can be measured as values in a mixed state of these.

The average primary particle diameter of the inorganic particles is, for example, 3nm or more and 200nm or less, preferably 5nm or more and 170nm or less, and more preferably 10nm or more and 100nm or less. When the average primary particle diameter is within the above range, the transparency of the dispersion is improved. Further, when the resin composition is used as a material for a sealing member of a light emitting element such as an LED, the luminance of the light emitting element (LED) can be improved.

The types, contents, and other components of the inorganic particles and the surface modification material in the dispersion are the same as those in the above-described mixed solution, and therefore, the description thereof is omitted.

However, when a decomposition reaction such as hydrolysis occurs when the surface modification material is attached to the inorganic particles, the content of the surface modification material in the dispersion can be reduced as compared with the content of the surface modification material in the mixed solution. Therefore, the total content of the surface-modifying material and the inorganic particles in the dispersion can also be reduced as compared with the total content of the surface-modifying material and the inorganic particles in the mixed liquid. Further, the amount of compounds generated by the decomposition reaction, for example, alcohol compounds in the dispersion can be increased as compared with the case of the mixed solution.

As described above, when the dispersion liquid according to the present embodiment is mixed with a material having high hydrophobicity, the inorganic particles can be uniformly dispersed in the material having high hydrophobicity, and white turbidity of the material having high hydrophobicity can be suppressed. The material having high hydrophobicity may be a material having low hydrophilicity. Examples of the material having high hydrophobicity can be arbitrarily selected, and examples thereof include organic solvents, resin materials, and oils and fats containing a large amount of carbon or hydrophobic groups. Examples of the organic solvent include preferably aromatic hydrocarbons, saturated hydrocarbons, and unsaturated hydrocarbons. One kind or two or more kinds may be used. More specific examples of the material having high hydrophobicity include silicone resins, for example, silicone containing a large amount of methyl groups such as dimethyl silicone resin. More specific examples of the material include methylphenylsilicone, toluene, methoxy-containing phenylsilicone resin, benzene, ethylbenzene, 1-phenylpropane, isopropylbenzene, n-butylbenzene, tert-butylbenzene, sec-butylbenzene, o-xylene, m-xylene, p-xylene, 2-ethyltoluene, 3-ethyltoluene, 4-ethyltoluene, and the like. However, the present invention is not limited thereto.

In addition, when the dispersion liquid according to the present embodiment is used, inorganic particles of fine particles can be uniformly dispersed in a material having high hydrophobicity. Therefore, the dispersion liquid according to the present embodiment is suitable as a material for an optical member, such as a sealing member of a light emitting element, which requires that inorganic particles of fine particles be uniformly dispersed in a highly hydrophobic material. Therefore, the dispersion liquid according to the present embodiment can be preferably used as a dispersion liquid for an optical member, particularly a dispersion liquid for a sealing member of a light-emitting element.

Examples

The present invention will be described in more detail below with reference to examples. The following examples are merely illustrative of the present invention and do not limit the present invention.

[ example 1]

(1. preparation of Dispersion)

(i) Hydrolysis step

90.78 parts by mass of methyltrimethoxysilane (product name KBM-13, manufactured by Shin-Etsu Chemical Co., Ltd.) as a surface modifier, 9.21 parts by mass of water, and 0.01 part by mass of hydrochloric acid (1N) were prepared. Adding them into a container, mixing them to obtain the hydrolysate. Subsequently, the hydrolysate was stirred at 60 ℃ for 30 minutes to hydrolyze methyltrimethoxysilane. In addition, methyltriethoxysilane and water added to the hydrolysate were approximately equal in moles.

(ii) Mixing procedure

30 parts by mass of zirconia particles (Sumitomo Osaka Cement co., ltd.) having an average primary particle size of 12nm and 70 parts by mass of the hydrolysate were mixed to obtain a mixed solution. The content of zirconia particles in the mixed solution was 30 mass%, the content of methyltrimethoxysilane was 63.5 mass%, and the total content of zirconia particles and methyltrimethoxysilane was 93.5 mass%.

(iii) Dispersing step

The mixture was dispersed at room temperature for 10 hours by a bead mill. Then, the beads were removed to obtain a dispersion liquid according to example 1.

The solid content (residual content after heating at 100 ℃ for 1 hour) of the dispersion was measured, and the amount of the solid content was 70% by mass.

(2. evaluation)

(2.1 evaluation of particle size distribution of Dispersion)

A part of the obtained dispersion was extracted, and D10, D50 and D90 of the dispersion adjusted to a solid content of 5 mass% with methanol were measured using a particle size distribution analyzer (manufactured by HORIBA, Ltd., model: SZ-100 SP). As a result, D10 was 15nm, D50 was 65nm, and D90 was 108 nm. Further, since the particles contained in the dispersion are treated with a large amount of the surface modifier, it is considered that the particles are basically only the zirconia particles to which the surface modifier is attached. Thus, the measured D10, D50, and D90 are considered to be D10, D50, and D90 of the zirconia particles to which the surface modifier is attached. Also, D90/D50 was 1.66.

(2.2 evaluation of mixing stability with hydrophobic resin)

The mixing stability with the hydrophobic resin was evaluated by the following method.

(i) Silicone treatment

First, a dispersion for evaluation was prepared. In the following evaluations (ii) to (v), the dispersion for evaluation was further subjected to additional treatment as necessary to obtain a final dispersion or a final composition, and used for each evaluation.

39.0 parts by mass of the dispersion according to example 1, 8.6 parts by mass of a methoxy group-containing phenyl silicone resin (Shin-Etsu Chemical co., ltd., KR217) and 52.4 parts by mass of toluene were added and mixed at 110 ℃ for 18 hours to obtain a dispersion for evaluation in which the surfaces of zirconia particles were silicone-treated.

In addition, in the above blending, the solid content of the obtained evaluation dispersion liquid was measured to be 70 mass%, and therefore toluene was added so that the solid content in the evaluation dispersion liquid became 30 mass%.

(ii) Evaluation of Dispersion (confirmation of uniformity of particle size of inorganic particles)

A part of the above-obtained evaluation dispersion was extracted, and toluene was further added to prepare a dispersion (final dispersion) in which the solid content was adjusted to 5 mass%. The dispersions were measured for D10, D50 and D90 using a particle size distribution meter (HORIBA, manufactured by Ltd., model: SZ-100 SP). As a result, D10 was 54nm, D50 was 108nm, and D90 was 213 nm. It is considered that the particles contained in the evaluation dispersion are basically only the zirconia particles to which the surface modifier has adhered. Therefore, the measured D10, D50, and D90 are considered to be D10, D50, and D90 of the zirconia particles in the dispersion.

(iii) Evaluation of mixing with hydrophobic resin (confirmation of aggregation inhibition)

5g of the obtained evaluation dispersion was mixed with 3.5g of methylphenylsilicone (Shin-Etsu Chemical Co., Ltd., KER-2500-B) to prepare a mixture.

Next, toluene was removed from the mixed solution by an evaporator to obtain a composition (final composition) for sealing an LED described later.

The appearance of the resulting composition was visually observed to be a transparent composition.

(iv) Evaluation of stability of the composition (confirmation of stability)

The viscosity of the composition (final composition) was measured using a rheometer (RheoStress RS-6000, manufactured by HAAKE) at 25 ℃ and a shear rate of 1 (1/s).

As a result, the viscosity immediately after the production was 10 pas.

The composition was stored at room temperature (25 ℃ C.) and the viscosity after 1 month was measured. As a result, the viscosity of the composition was 50 pas, and the composition was thickened but could be of a level that could withstand practical use.

(v) Production of LED Package (confirmation of use of light emitting element)

To 1 part by mass of the obtained composition (final composition), 14 parts by mass of a methylphenyl silicone resin ("KER-2500-a/B" manufactured by Shin-Etsu Chemical co., ltd.) was added so that the surface-modified zirconia particles became 2% by mass in the composition, and the mixture was mixed. 0.38 parts by mass of phosphor particles (yttrium aluminum garnet: YAG) was mixed with 1 part by mass of the obtained composition. The obtained composition (total amount of the surface-modified zirconia particles and the resin: phosphor particles: 100:38) was filled into an LED lead frame at a thickness of 300 μm. Then, it was kept at room temperature for 3 hours. Subsequently, the composition was gradually heated and cured to form a sealing member, thereby producing a white LED package.

The obtained white LED package was measured for brightness by applying a voltage of 3V and a current of 150mA to the LED package using a full beam measurement system (manufactured by Otsuka Electronics co., ltd.). As a result, the luminance of the white LED package was 73.2 lm.

[ example 2]

Evaluation was performed in the same manner as in example 1 except that zirconia particles having different particle diameters were used.

(1. preparation of Dispersion)

Zirconia particles having an average primary particle diameter of 90nm (manufactured by Sumitomo Osaka Cement co., ltd.) were used instead of the zirconia particles having an average primary particle diameter of 12 nm. Except for this, the hydrolysis step, the mixing step, and the dispersion step were performed in the same manner as in example 1 to obtain a dispersion liquid according to example 2. The content of zirconia particles in the mixed solution obtained in the mixing step was 30 mass%, the content of methyltrimethoxysilane was 63.5 mass%, and the total content of zirconia particles and methyltrimethoxysilane was 93.5 mass%.

The solid content of the dispersion (1 hour at 100 ℃) was measured, and the result was 70% by mass.

(2. evaluation)

(2.1 evaluation of particle size distribution of Dispersion)

In the same manner as in example 1, D10, D50 and D90 of the inorganic particles in the dispersion were measured. As a result, D10 was 54nm, D50 was 120nm, and D90 was 223 nm. D90/D50 was 1.86.

(2.2 evaluation of mixing stability with hydrophobic resin)

(i) Silicone treatment

A dispersion for evaluation having a solid content of 30 mass% was obtained by performing silicone treatment in the same manner as in example 1 except that the dispersion of example 2 was used instead of the dispersion of example 1.

(ii) Evaluation of Dispersion

The evaluation of the dispersion for evaluation was carried out in the same manner as in example 1, and D10 was 95nm, D50 was 184nm, and D90 was 284 nm.

(iii) Evaluation of mixing with hydrophobic resin

The obtained evaluation dispersion was mixed with methylphenylsilicone in the same manner as in example 1, and toluene was removed to obtain a composition. The appearance of the resulting composition was visually observed to be a transparent composition.

(iv) Evaluation of stability of composition

The viscosity of the composition was measured at 25 ℃ and a shear rate of 1(1/s) using a rheometer (RheoStress RS-6000, manufactured by HAAKE).

As a result, the viscosity immediately after the production was 10 pas.

The composition was stored at room temperature (25 ℃ C.) and the viscosity after 1 month was measured. As a result, the viscosity of the composition was 40Pa · s, and the composition was of a level that could withstand practical use although thickened.

Comparative example 1

Evaluation was performed in the same manner as in example 1 except that isopropanol was added to the hydrolysate at a high ratio.

(1. preparation of Dispersion)

In the mixing step, 20 parts by mass of the hydrolysate and 50 parts by mass of isopropyl alcohol were used instead of 70 parts by mass of the hydrolysate. Except for this, the hydrolysis step, the mixing step, and the dispersion step were performed in the same manner as in example 1 to obtain a dispersion liquid (solid content 30 mass%) according to comparative example 1. The content of zirconia particles in the mixed solution obtained in the mixing step was 30 mass%, the content of methyltrimethoxysilane was 18.2 mass%, and the total content of zirconia particles and methyltrimethoxysilane was 48.2 mass%.

The solid content of the 1 st dispersion (1 hour at 100 ℃) was measured, and found to be 38% by mass.

(2. evaluation)

(2.1 evaluation of particle size distribution of Dispersion)

In the same manner as in example 1, D10, D50 and D90 of the inorganic particles in the dispersion were measured. As a result, D10 was 13nm, D50 was 62nm, and D90 was 95 nm. D90/D50 was 1.53.

(2.2 evaluation of mixing stability with hydrophobic resin)

(i) Silicone treatment

A dispersion for evaluation having a solid content of 30 mass% was obtained by performing a silicone treatment 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.

(ii) Evaluation of Dispersion

The evaluation of the dispersion for evaluation was carried out in the same manner as in example 1, and D10 was 52nm, D50 was 105nm, and D90 was 195 nm.

(iii) Evaluation of mixing with hydrophobic resin

The obtained evaluation dispersion was mixed with methylphenylsilicone in the same manner as in example 1, and toluene was removed to obtain a composition.

As a result of removal of the toluene, the resulting composition was cloudy/gelled.

(iv) Evaluation of stability of composition

The viscosity of the composition was not measured because of cloudiness and gelation.

(v) Manufacturing of LED package

A cloudy/gelled composition was obtained, and no composition capable of encapsulating LEDs was obtained. Therefore, the LED package cannot be manufactured.

In addition, when comparing the dispersions of comparative example 1 and example 1, the particle size distribution (D90/D50) of the dispersion obtained in example 1 is larger than that of comparative example 1 and slightly inferior because the zirconia particles are dispersed in the surface-modifying material at a high concentration. This is presumably because the dispersion liquid of example 1 contains a large amount of the surface-treated material, and therefore has a high viscosity and is a condition under which dispersion is difficult.

However, the dispersions of examples 1 and 2, in which the zirconia particles were dispersed in the surface-modifying material at a high concentration, did not cause cloudiness with respect to the resin having high hydrophobicity, and thus transparent compositions were obtained. On the other hand, when the dispersion liquid according to comparative example 1 was mixed with a hydrophobic resin, white turbidity occurred, and a transparent composition could not be obtained. These are surprising results that have not been known before.

Industrial applicability

Provided are a method for modifying the surface of inorganic particles, a method for producing a dispersion, and a dispersion, for obtaining inorganic particles that are prevented from aggregating and generating turbidity such as white turbidity even when mixed with a material having high hydrophobicity.