JP7190431B2 - Coated inorganic fine particles and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to coated inorganic fine particles having a coating layer obtained by reacting a specific compound on the surface of inorganic fine particles, and a method for producing the same.

Conventionally, in order to obtain a composite material that requires transparency, a dispersion is first produced by dispersing nano-sized inorganic fine particles in a liquid such as an organic solvent, and then the dispersion is mixed with a resin or the like. A common method is to remove the organic solvent (see Patent Documents 1 to 8, for example).
However, the conventional method imposes an energy load in the process of producing the dispersion liquid and removing the organic solvent, and the work efficiency is poor due to the inclusion of extra processes.

In addition, among the applications where transparent nanocomposite materials are required, adhesives used in organic electroluminescence (hereinafter sometimes abbreviated as "organic EL"), which is one of flat panel displays, and light emission There is a sealing material used for diodes (hereinafter sometimes abbreviated as "LED"), and when the adhesive or sealing material is cured by ultraviolet light or heat, outgassing is generated due to heat generation. It is known that it adversely affects the life of the battery (see, for example, Patent Documents 9 and 10).

In transparent nanocomposite materials, there is a method of directly dispersing nano-sized inorganic fine particles with a particle diameter of 20 nm or less in solvent-free monomers, oligomers, and resins using a dispersing machine such as a bead mill. Since the specific surface area is large, the van der Waals force between particles is strong, making it difficult to uniformly disperse the particles. If the viscosity rises, a load is applied to the apparatus, and the beads cannot be stirred. In addition, when the inorganic fine particles are dispersed in the resin at a high concentration, transparency cannot be obtained and the viscosity of the composite material becomes extremely high, which limits the mixing ratio and adversely affects handling during molding. occurs.

In Patent Documents 11 and 12, in order to solve the problem of high viscosity in a composite material due to dispersion of nanoparticles, particles having a primary particle diameter of 15 nm or less are granulated into spherical or plate-shaped particles of about several tens of μm, and the granulation is performed. We have proposed a method of obtaining a transparent composite by coating the surface of particles with a silane coupling agent and then mixing and stirring the particles with an epoxy or silicone resin.
However, in these production methods, even if the crystallite diameter is 15 nm or less, the particle size is about several tens of μm, so it is difficult to apply to thin film applications. However, there is a problem that the transparency and hardness of the composite are adversely affected.

In Patent Document 13, powder of inorganic oxide fine particles such as ZrO ₂ whose surface is coated with a carboxylic acid having 4 or more carbon atoms to make it hydrophobic is mixed with a polystyrene resin to obtain a highly transparent polystyrene composite. In the surface coating method, first, hydrophobization is performed with an aqueous dispersion of inorganic oxide fine particles, and after mixing a non-water-soluble organic solvent such as toluene and an amphoteric organic solvent such as methanol, water and the amphoteric organic solvent are mixed. Evaporation is carried out to form a water-insoluble organic solvent inorganic oxide fine particle dispersion, and then the water-insoluble organic solvent is evaporated away.
However, in this production method, the operation of mixing the water-insoluble organic solvent and the amphoteric organic solvent and removing them by evaporation is repeated 5 to 6 times. Therefore, it is difficult to completely remove the organic solvent even by evaporation. In addition, since the organic compound for surface coating is limited to a carboxylic acid having 4 or more carbon atoms, it is difficult to match compatibility in the case of a mixture containing various monomers and resins alone or several types.

In Patent Document 14, since a zirconia-containing epoxy resin composition is obtained by the same production method as in Patent Document 13, there are problems similar to those in Patent Document 13. In addition, zirconia particles synthesized by a wet method as described in Patent Document 14 have low crystallinity and contain many impurities such as chloride ions and sulfate ions. Furthermore, since zirconia is synthesized from a zirconia precursor by heat treatment, the particles are bonded or agglomerated, and there is a problem that the transparency and weather resistance of the zirconia-containing epoxy resin composition are adversely affected.

In Patent Document 15, SiO ₂ nanoparticles are heat-treated in a monomer liquid while stirring to form a monomer-derived molecular film having a thickness of 1 nm or less on the surface, and then another monomer and catalyst are added and heated. proposed a transparent composite material made of a silicone-based polymer crosslinked by
However, in this manufacturing method, the compatibility with silicone-based polymers is important, which limits the use of _SiO2 nanoparticles as inorganic fine particles. In the case of using other inorganic fine particles, it is necessary to apply a surface coating to the particle surface, so this method cannot be applied. In addition, since the refractive index of the _SiO2 nanoparticles is close to that of the silicone-based polymer, transparency is obtained even if the particles are not uniformly dispersed in the resin. It is difficult to maintain transparency when _SiO2 nanoparticles are dispersed in a high concentration or in the case of other inorganic fine particles.

In addition, Patent Documents 16 to 19 provide a composite material in which a powder of inorganic fine particles surface-coated with a silane coupling agent, methacrylate, or the like is directly dispersed in a resin, and a method for producing the same. is dispersed, the surface is coated, and the organic solvent is removed by evaporation. Therefore, it is difficult to completely remove the organic solvent. In addition, since a dispersing step using a dispersing machine such as a bead mill for inorganic fine particles and a removing step of the organic solvent are required, industrial-scale production is difficult due to the energy load and waste liquid treatment of the organic solvent.

JP-A-2003-73558 JP 2006-299126 A JP 2008-156390 A JP 2009-185185 A JP 2010-209186 A JP 2011-79927 A JP 2014-28873 A JP 2016-28998 A JP 2005-251631 A JP 2014-201617 A JP 2007-308345 A JP 2010-6647 A JP 2011-105553 A JP 2014-221866 A Japanese Unexamined Patent Application Publication No. 2012-251110 JP 2008-280443 A JP 2009-40938 A JP 2009-74023 A JP 2011-524444 A

The present invention has been made in view of the above circumstances, and provides coated inorganic fine particles suitable for transparent nanocomposite materials used in optical members, electronic members, coating materials, dental materials, and the like, and a method for producing the same. intended to

（式（Ａ－１）、（Ａ－２）、（Ｂ－１）、（Ｂ－２）、（Ｃ）、（Ｄ－１）、及び（Ｄ－２）中、Ｒ^１はそれぞれ独立してヘテロ原子を含んでいてもよい炭素原子数１～２０の炭化水素基を、Ｒ^２はヘテロ原子を含んでいてもよい炭素原子数１～２０のｊ価の炭化水素基、又はケイ素原子数１～２０のｊ価の（ポリ）シロキシ基を、Ｒ^３及びＲ^４はそれぞれ独立して下記式（ｂｃ－１）～（ｂｃ－６）の何れかで表される構造を、Ｒ^５はヘテロ原子を含んでいてもよい炭素原子数４～３０の炭化水素基を、Ｒ^６はヘテロ原子を含んでいてもよい炭素原子数１～２０のｎ価の炭化水素基を、Ｘ^１はそれぞれ独立して炭素原子数１～１０のアルコキシ基、水素原子、塩素原子、臭素原子、又はヨウ素原子を、Ｘ^２及びＸ^３はそれぞれ独立して炭素原子数１～１０のアルコキシ基、ヘテロ原子を含んでいてもよい炭素原子数１～１０のアシロキシ基、塩素原子、臭素原子、又はヨウ素原子を、ｈは１～４の整数を、ｉはそれぞれ独立して１～３の整数を、ｊは２～１０の整数を、ｋは１～４の整数を、ｌは１～３の整数を、ｍは１～３の整数を、ｎは２～１０の整数を表す。但し、Ｘ^２及びＸ^３のアルコキシ基及び／又はアシロキシ基は、それぞれＸ^２及びＸ^３の他のアルコキシ基及び／又はアシロキシ基と結合して環状構造を形成していてもよい。）

（式（ｂｃ－１）～（ｂｃ－６）中、Ｒ^７はそれぞれ独立してヘテロ原子を含んでいてもよい炭素原子数１～３０の炭化水素基を、Ｒ^８はヘテロ原子を含んでいてもよい炭素原子数１～３０の炭化水素基を、Ｒ^９はそれぞれ独立してヒドロキシル基、ヘテロ原子を含んでいてもよい炭素原子数１～２０のアルコキシ基、ヘテロ原子を含んでいてもよい炭素原子数１～２０の炭化水素基、又は水素原子を表す。）
［２］ 前記揮発性有機化合物の含有量が、１ｐｐｍ以上８０ｐｐｍ未満である、［１］に記載の被覆無機微粒子。
［３］ 屈折率が１．５以上である、［１］又は［２］に記載の被覆無機微粒子。
［４］ 前記無機微粒子が、屈折率１．５以上の金属酸化物からなる群より選択される少なくとも１種である、［１］～［３］の何れかに記載の被覆無機微粒子。
［５］ 前記無機微粒子が、二酸化ジルコニウム（ＺｒＯ_２）及び二酸化チタン（ＴｉＯ_２）からなる群より選択される少なくとも１種である、［１］～［４］の何れかに記載の被覆無機微粒子。
［６］ 前記被覆層が、前記式（Ａ－１）で表される化合物又は前記式（Ａ－２）で表される化合物を反応させて形成される層である、［１］～［５］の何れかに記載の被覆無機微粒子。
［７］ 前記式（Ａ－１）、（Ａ－２）、（Ｂ－１）、（Ｂ－２）、（Ｃ）、（Ｄ－１）、及び（Ｄ－２）の何れかで表される化合物が、前記無機微粒子１００重量部に対して、３重量部以上１００重量部以下添加されて反応させられる、［１］～［６］の何れかに記載の被覆無機微粒子。
［８］ 前記被覆層の含有量が、１重量％以上４５重量％以下である、［１］～［７］の何れかに記載の被覆無機微粒子。
［９］ 金属水酸化物及び／又は金属水酸化物の縮合物が溶解及び／又は分散する水溶液を準備する準備工程、（２）前記準備工程で準備した前記水溶液を温度２００℃以上、圧力２０ＭＰａ以上、反応時間０．１分以上で水熱反応させて無機微粒子を生成する水熱反応工程、（３）前記水熱反応工程で生成した前記無機微粒子を単離する単離工程、（４）前記単離工程で単離した前記無機微粒子と下記式（Ａ－１）、（Ａ－２）、（Ｂ－１）、（Ｂ－２）、（Ｃ）、（Ｄ－１）、及び（Ｄ－２）の何れかで表される化合物の少なくとも1種を水溶媒中で反応させる被覆工程、を含むことを特徴とする被覆無機微粒子の製造方法。

（式（Ａ－１）、（Ａ－２）、（Ｂ－１）、（Ｂ－２）、（Ｃ）、（Ｄ－１）、及び（Ｄ－２）中、Ｒ^１はそれぞれ独立してヘテロ原子を含んでいてもよい炭素原子数１～２０の炭化水素基を、Ｒ^２はヘテロ原子を含んでいてもよい炭素原子数１～２０のｊ価の炭化水素基、又はケイ素原子数１～２０のｊ価の（ポリ）シロキシ基を、Ｒ^３及びＲ^４はそれぞれ独立して下記式（ｂｃ－１）～（ｂｃ－６）の何れかで表される構造を、Ｒ^５はヘテロ原子を含んでいてもよい炭素原子数４～３０の炭化水素基を、Ｒ^６はヘテロ原子を含んでいてもよい炭素原子数１～２０のｎ価の炭化水素基を、Ｘ^１はそれぞれ独立して炭素原子数１～１０のアルコキシ基、水素原子、塩素原子、臭素原子、又はヨウ素原子を、Ｘ^２及びＸ^３はそれぞれ独立して炭素原子数１～１０のアルコキシ基、ヘテロ原子を含んでいてもよい炭素原子数１～１０のアシロキシ基、塩素原子、臭素原子、又はヨウ素原子を、ｈは１～４の整数を、ｉはそれぞれ独立して１～３の整数を、ｊは２～１０の整数を、ｋは１～４の整数を、ｌは１～３の整数を、ｍは１～３の整数を、ｎは２～１０の整数を表す。但し、Ｘ^２及びＸ^３のアルコキシ基及び／又はアシロキシ基は、それぞれＸ^２及びＸ^３の他のアルコキシ基及び／又はアシロキシ基と結合して環状構造を形成していてもよい。）

（式（ｂｃ－１）～（ｂｃ－６）中、Ｒ^７はそれぞれ独立してヘテロ原子を含んでいてもよい炭素原子数１～３０の炭化水素基を、Ｒ^８はヘテロ原子を含んでいてもよい炭素原子数１～３０の炭化水素基を、Ｒ^９はそれぞれ独立してヒドロキシル基、ヘテロ原子を含んでいてもよい炭素原子数１～２０のアルコキシ基、ヘテロ原子を含んでいてもよい炭素原子数１～２０の炭化水素基、又は水素原子を表す。）
［１０］ ［１］～［８］の何れかに記載の被覆無機微粒子を透明な有機化合物に分散させてなるナノコンポジット材料。
［１１］ 前記有機化合物が、前記有機化合物が、重合性のモノマー及び／又はオリゴマーであり、前記モノマー及び／又はオリゴマーを重合させたときの重合体の波長４００ｎｍの光の分光透過率が６５％以上である、［１０］に記載のナノコンポジット材料。
［１２］ 前記有機化合物が、熱可塑性樹脂、熱硬化性樹脂、紫外線硬化性樹脂、及び電子線硬化性樹脂からなる群より選択される少なくとも１種であり、波長４００ｎｍの光の分光透過率が６５％以上である、［１０］のナノコンポジット材料。
［１３］ 前記被覆無機微粒子の含有量が、１０重量％以上８５重量％以下である、［１０］～［１２］の何れかに記載のナノコンポジット材料。The inventors of the present invention conducted intensive studies to solve these problems, and found that coated inorganic fine particles having a coating layer obtained by reacting a specific compound on the surface of the inorganic fine particles (hereinafter referred to as "coated inorganic fine particles") It may be omitted.), and the coated inorganic fine particles that satisfy specific conditions and suppress the content of volatile organic compounds are excellent in mass production, do not aggregate even at high concentrations, and uniformly disperse inorganic fine particles. The inventors have found that a transparent nanocomposite material can be realized, and completed the present invention.
That is, according to the present invention, the following embodiments are provided.
[1] The following formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2) are applied to the surface of the inorganic fine particles A coated inorganic fine particle having a coating layer obtained by reacting at least one of a compound represented by any of and a salt thereof,
The inorganic fine particles have an average particle diameter of 1 nm or more and less than 100 nm, and a specific surface area of 1 m ² /g or more and less than 3,000 m ² /g,
Coated inorganic fine particles, characterized in that the content of volatile organic compounds is less than 100 ppm.

(In formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2), R ¹ is is a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, R ² is a j-valent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, or the number of silicon atoms 1 to 20 j-valent (poly)siloxy groups, R ³ and R ⁴ each independently have a structure represented by any one of the following formulas (bc-1) to (bc-6), R ⁵ R 6 is a hydrocarbon group having 4 to 30 carbon atoms which may contain a heteroatom, R ⁶ is an n-valent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, and X ¹ is each X ² and X ³ are each independently an alkoxy group having 1 to 10 carbon atoms, a hydrogen atom, a chlorine atom, a bromine atom, or an iodine atom, and each independently an alkoxy group having 1 to 10 carbon atoms or a hetero atom may contain an acyloxy group having 1 to 10 carbon atoms, a chlorine atom, a bromine atom, or an iodine atom, h is an integer of 1 to 4, i is each independently an integer of 1 to 3, and j is an integer of 2 to 10, k an integer of 1 to 4, l an integer of 1 to 3, m an integer of 1 to 3, and n an integer of 2 to 10, provided that X ² and X The alkoxy group and/or acyloxy group of ³ may combine with other alkoxy group and/or acyloxy group of X2 and ^{X3 respectively} to form a cyclic structure.)

(In formulas (bc-1) to (bc-6), R ⁷ is each independently a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom, and R ⁸ contains a heteroatom. Each R ⁹ is independently a hydroxyl group, an alkoxy group with 1 to 20 carbon atoms which may contain a heteroatom, and a It represents a good hydrocarbon group with 1 to 20 carbon atoms, or a hydrogen atom.)
[2] The coated inorganic fine particles according to [1], wherein the content of the volatile organic compound is 1 ppm or more and less than 80 ppm.
[3] The coated inorganic fine particles according to [1] or [2], which have a refractive index of 1.5 or more.
[4] The coated inorganic fine particles according to any one of [1] to [3], wherein the inorganic fine particles are at least one selected from the group consisting of metal oxides having a refractive index of 1.5 or more.
[5] The coated inorganic fine particles according to any one of [1] to [4], wherein the inorganic fine particles are at least one selected from the group consisting of zirconium dioxide (ZrO ₂ ) and titanium dioxide (TiO ₂ ). .
[6] The coating layer is a layer formed by reacting the compound represented by the formula (A-1) or the compound represented by the formula (A-2), [1] to [5] ].
[7] Represented by any of the formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2) The coated inorganic fine particles according to any one of [1] to [6], wherein the compound is added to 100 parts by weight of the inorganic fine particles in an amount of 3 parts by weight or more and 100 parts by weight or less to react.
[8] The coated inorganic fine particles according to any one of [1] to [7], wherein the content of the coating layer is 1% by weight or more and 45% by weight or less.
[9] A preparatory step of preparing an aqueous solution in which metal hydroxides and/or metal hydroxide condensates are dissolved and/or dispersed; (3) an isolation step of isolating the inorganic fine particles produced in the hydrothermal reaction step; (4) The inorganic fine particles isolated in the isolation step and the following formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and ( A method for producing coated inorganic fine particles, comprising a coating step of reacting at least one compound represented by any one of D-2) in an aqueous solvent.

(In formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2), R ¹ is is a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, R ² is a j-valent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, or the number of silicon atoms 1 to 20 j-valent (poly)siloxy groups, R ³ and R ⁴ each independently have a structure represented by any one of the following formulas (bc-1) to (bc-6), R ⁵ R 6 is a hydrocarbon group having 4 to 30 carbon atoms which may contain a heteroatom, R ⁶ is an n-valent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, and X ¹ is each X ² and X ³ are each independently an alkoxy group having 1 to 10 carbon atoms, a hydrogen atom, a chlorine atom, a bromine atom, or an iodine atom, and each independently an alkoxy group having 1 to 10 carbon atoms or a hetero atom may contain an acyloxy group having 1 to 10 carbon atoms, a chlorine atom, a bromine atom, or an iodine atom, h is an integer of 1 to 4, i is each independently an integer of 1 to 3, and j is an integer of 2 to 10, k an integer of 1 to 4, l an integer of 1 to 3, m an integer of 1 to 3, and n an integer of 2 to 10, provided that X ² and X The alkoxy group and/or acyloxy group of ³ may combine with other alkoxy group and/or acyloxy group of X2 and ^{X3 respectively} to form a cyclic structure.)

(In formulas (bc-1) to (bc-6), R ⁷ is each independently a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom, and R ⁸ contains a heteroatom. Each R ⁹ is independently a hydroxyl group, an alkoxy group with 1 to 20 carbon atoms which may contain a heteroatom, and a It represents a good hydrocarbon group with 1 to 20 carbon atoms, or a hydrogen atom.)
[10] A nanocomposite material obtained by dispersing the coated inorganic fine particles according to any one of [1] to [8] in a transparent organic compound.
[11] The organic compound is a polymerizable monomer and/or oligomer, and the polymer obtained by polymerizing the monomer and/or oligomer has a spectral transmittance of 65% for light at a wavelength of 400 nm. The nanocomposite material according to [10], which is the above.
[12] The organic compound is at least one selected from the group consisting of thermoplastic resins, thermosetting resins, ultraviolet curable resins, and electron beam curable resins, and has a spectral transmittance of light having a wavelength of 400 nm. 65% or more, the nanocomposite material of [10].
[13] The nanocomposite material according to any one of [10] to [12], wherein the content of the coated inorganic fine particles is 10% by weight or more and 85% by weight or less.

According to the present invention, it is possible to provide coated inorganic fine particles that are excellent in mass productivity, do not aggregate even at a high concentration, and can realize a transparent nanocomposite material in which the inorganic fine particles are uniformly dispersed. In addition, the method for producing the material of the present invention has a high energy load and poor work efficiency, and can omit the steps of dispersing in an organic solvent and removing the organic solvent, so that the production cost is relatively reduced, and the scale of industrialization is useful for the production of

FIG. 1 is a transmission electron microscope (TEM) photograph (×200,000) showing the particle morphology of zirconia fine particles of 10 nm shown in Production Example 1. FIG. 2 is a transmission electron microscope (TEM) photograph (×200,000) showing the particle morphology of 10 nm titania fine particles shown in Production Example 2. FIG. FIG. 3 is a transmission electron microscope (TEM) photograph (×200,000) showing the particle morphology of zirconia fine particles of 10 nm each having a coating layer obtained in Example 1. FIG. 4 is a transmission electron microscope (TEM) photograph (×200,000) showing the particle morphology of 10 nm titania fine particles having a coating layer obtained in Example 10. FIG.

MODE FOR CARRYING OUT THE INVENTION

The present invention will be described below based on preferred embodiments, but the present invention is not limited to these descriptions.

（式（Ａ－１）、（Ａ－２）、（Ｂ－１）、（Ｂ－２）、（Ｃ）、（Ｄ－１）、及び（Ｄ－２）中、Ｒ^１はそれぞれ独立してヘテロ原子を含んでいてもよい炭素原子数１～２０の炭化水素基を、Ｒ^２はヘテロ原子を含んでいてもよい炭素原子数１～２０のｊ価の炭化水素基、又はケイ素原子数１～２０のｊ価の（ポリ）シロキシ基を、Ｒ^３及びＲ^４はそれぞれ独立して下記式（ｂｃ－１）～（ｂｃ－６）の何れかで表される構造を、Ｒ^５はヘテロ原子を含んでいてもよい炭素原子数４～３０の炭化水素基を、Ｒ^６はヘテロ原子を含んでいてもよい炭素原子数１～２０のｎ価の炭化水素基を、Ｘ^１はそれぞれ独立して炭素原子数１～１０のアルコキシ基、水素原子、塩素原子、臭素原子、又はヨウ素原子を、Ｘ^２及びＸ^３はそれぞれ独立して炭素原子数１～１０のアルコキシ基、ヘテロ原子を含んでいてもよい炭素原子数１～１０のアシロキシ基、塩素原子、臭素原子、又はヨウ素原子を、ｈは１～４の整数を、ｉはそれぞれ独立して１～３の整数を、ｊは２～１０の整数を、ｋは１～４の整数を、ｌは１～３の整数を、ｍは１～３の整数を、ｎは２～１０の整数を表す。但し、Ｘ^２及びＸ^３のアルコキシ基及び／又はアシロキシ基は、それぞれＸ^２及びＸ^３の他のアルコキシ基及び／又はアシロキシ基と結合して環状構造を形成していてもよい。）

（式（ｂｃ－１）～（ｂｃ－６）中、Ｒ^７はそれぞれ独立してヘテロ原子を含んでいてもよい炭素原子数１～３０の炭化水素基を、Ｒ^８はヘテロ原子を含んでいてもよい炭素原子数１～３０の炭化水素基を、Ｒ^９はそれぞれ独立してヒドロキシル基、ヘテロ原子を含んでいてもよい炭素原子数１～２０のアルコキシ基、ヘテロ原子を含んでいてもよい炭素原子数１～２０の炭化水素基、又は水素原子を表す。）
本発明者らは、揮発性有機化合物の含有量を抑制した前述の被覆無機微粒子が、量産性に優れ、高濃度でも凝集せず、無機微粒子が均一に分散した透明なナノコンポジット材料を実現できることを見出したのである。
なお、本発明における「無機微粒子」は、例えば高温高圧条件下の水熱反応によって調製することができる。高温高圧条件下の水熱反応によって調製した無機微粒子は、従来の固相反応法、湿式反応法、気相法、低温低圧条件下の水熱反応法と比較して、どのような溶媒に対しても分散性に優れ、粒子形状が均一で比表面積が大きくなる特長を有する。また、粒子表面の反応性が高く、「被覆剤」と均一に反応するため、揮発有機化合物が残存しにくくなるものと考えられる。その結果、モノマー、オリゴマー、樹脂等の有機化合物との相溶性に優れ、無機微粒子の粉末を無溶剤系の有機化合物に直接分散することが可能になり、揮発性有機化合物の含有量が少なく、透明ナノコンポジットにおいても硬化の際に揮発性有機化合物を殆ど生じないものと考えられる。
また、本発明における「無機微粒子」の表面と「被覆剤」との反応は、例えば水溶媒中で行うことができる。従来の無機微粒子の表面処理方法として、ビーズミル等の湿式分散機により、無機微粒子の粉末を有機溶剤中に均一分散してから、又は分散しながらシランカップリング剤等により表面被覆を行っているが、無機微粒子が粉砕されたり、二次凝集したりした状態での表面処理となるため、粒子表面に有機化合物を均一に被覆することが困難である。また、ビーズミルの場合では使用する数十μｍ程度のビーズに有機化合物が多く付着してしまうため、精密な制御が困難であり、製造コストの増加を招く。さらに表面処理の際に有機溶剤を使用すると、その後乾燥処理を行っても完全に有機溶剤を取り除くことができず、無機微粒子の被覆層由来の揮発性有機化合物を多く含んでしまうのである。
即ち、本発明の被覆無機微粒子は、どのような溶媒に対しても分散性に優れ、粒子形状が均一で比表面積が高く、さらに揮発性有機化合物の含有量を抑制するように調製された被覆無機微粒子なのである。
なお、式（ｂｃ－１）～（ｂｃ－６）中の波線は、その先でチタン原子（Ｔｉ）やアルミニウム原子（Ａｌ）に結合していることを意味し、式（ｂｃ－４）はリン原子（Ｐ）の孤立電子対等でチタン原子（Ｔｉ）やアルミニウム原子（Ａｌ）に配位していることを意味するものとする。
以下、「無機微粒子」、「被覆剤」、「被覆層」、「揮発性有機化合物」等について詳細に説明する。<Coated inorganic fine particles>
Coated inorganic fine particles (hereinafter, sometimes abbreviated as "coated inorganic fine particles of the present invention"), which is one embodiment of the present invention, are provided on the surfaces of inorganic fine particles (hereinafter, sometimes abbreviated as "inorganic fine particles") as follows. Compounds represented by any of formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2) and It is coated inorganic fine particles having a coating layer, obtained by reacting at least one salt thereof (hereinafter sometimes abbreviated as “coating agent”). The inorganic fine particles have an average particle diameter of 1 nm or more and less than 100 nm, a specific surface area of 1 m ² /g or more and less than 3,000 m ² /g, and a volatile organic compound content of less than 100 ppm. do.

(In formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2), R ¹ is is a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, R ² is a j-valent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, or the number of silicon atoms 1 to 20 j-valent (poly)siloxy groups, R ³ and R ⁴ each independently have a structure represented by any one of the following formulas (bc-1) to (bc-6), R ⁵ R 6 is a hydrocarbon group having 4 to 30 carbon atoms which may contain a heteroatom, R ⁶ is an n-valent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, and X ¹ is each X ² and X ³ are each independently an alkoxy group having 1 to 10 carbon atoms, a hydrogen atom, a chlorine atom, a bromine atom, or an iodine atom, and each independently an alkoxy group having 1 to 10 carbon atoms or a hetero atom may contain an acyloxy group having 1 to 10 carbon atoms, a chlorine atom, a bromine atom, or an iodine atom, h is an integer of 1 to 4, i is each independently an integer of 1 to 3, and j is an integer of 2 to 10, k an integer of 1 to 4, l an integer of 1 to 3, m an integer of 1 to 3, and n an integer of 2 to 10, provided that X ² and X The alkoxy group and/or acyloxy group of ³ may combine with other alkoxy group and/or acyloxy group of X2 and ^{X3 respectively} to form a cyclic structure.)

(In formulas (bc-1) to (bc-6), R ⁷ is each independently a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom, and R ⁸ contains a heteroatom. Each R ⁹ is independently a hydroxyl group, an alkoxy group with 1 to 20 carbon atoms which may contain a heteroatom, and a It represents a good hydrocarbon group with 1 to 20 carbon atoms, or a hydrogen atom.)
The inventors of the present invention have found that the above-described coated inorganic fine particles with a suppressed content of volatile organic compounds can realize a transparent nanocomposite material in which the inorganic fine particles are uniformly dispersed without agglomerating even at a high concentration, which is excellent in mass production. I found this.
The "inorganic fine particles" in the present invention can be prepared, for example, by hydrothermal reaction under high temperature and high pressure conditions. Inorganic fine particles prepared by hydrothermal reaction under high temperature and high pressure conditions are more resistant to solvents than conventional solid phase reaction methods, wet reaction methods, gas phase methods, and hydrothermal reaction methods under low temperature and low pressure conditions. It is characterized by excellent dispersibility, uniform particle shape, and large specific surface area. In addition, since the particle surface has high reactivity and uniformly reacts with the "coating agent", it is considered that the volatile organic compounds are less likely to remain. As a result, it has excellent compatibility with organic compounds such as monomers, oligomers, and resins, and it is possible to directly disperse the powder of inorganic fine particles in solvent-free organic compounds, and the content of volatile organic compounds is low. It is believed that even the transparent nanocomposite hardly produces volatile organic compounds during curing.
Further, the reaction between the surface of the "inorganic fine particles" and the "coating agent" in the present invention can be carried out, for example, in an aqueous solvent. As a conventional surface treatment method for inorganic fine particles, the surface is coated with a silane coupling agent or the like after uniformly dispersing the powder of inorganic fine particles in an organic solvent using a wet dispersing machine such as a bead mill or while the particles are being dispersed. Since the surface treatment is performed while the inorganic fine particles are pulverized or secondary agglomerated, it is difficult to evenly coat the surface of the particles with the organic compound. Moreover, in the case of a bead mill, a large amount of the organic compound adheres to beads of about several tens of micrometers, which makes precise control difficult and increases manufacturing costs. Furthermore, if an organic solvent is used in the surface treatment, the organic solvent cannot be completely removed even if the subsequent drying treatment is performed, resulting in a large amount of volatile organic compounds derived from the coating layer of the inorganic fine particles.
That is, the coated inorganic fine particles of the present invention are excellent in dispersibility in any solvent, have a uniform particle shape and a high specific surface area, and are coated so as to suppress the content of volatile organic compounds. They are inorganic fine particles.
Note that the wavy lines in the formulas (bc-1) to (bc-6) mean that they are bonded to a titanium atom (Ti) or an aluminum atom (Al) at the tip, and the formula (bc-4) is It means that a lone electron pair of a phosphorus atom (P) is coordinated to a titanium atom (Ti) or an aluminum atom (Al).
Hereinafter, "inorganic fine particles", "coating agent", "coating layer", "volatile organic compound" and the like will be described in detail.

The material and particle shape of the inorganic fine particles are not particularly limited as long as they have an average particle diameter of 1 nm or more and less than 100 nm and a specific surface area of 1 m ² /g or more and less than 3,000 m ² /g. , metal oxides, metal hydroxides, metal nitrides, metal carbides, metals, and the like.
Metal oxides, metal hydroxides, metal nitrides, metal carbides, metal elements of metals are not limited to one type, and composite metal oxides containing two or more types of metal elements, composite metal nitrides, composite metal carbides, It may be an alloy or the like.
As metal elements such as metal oxides, metal nitrides, metal carbides and metals,
Periodic Table Group 1 elements (alkali metal elements) such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs);
Periodic Table Group 2 elements (alkaline earth metal elements) such as beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba);
Group 3 elements of the periodic table such as scandium (Sc), yttrium (Y), lanthanides, actinides;
Periodic Table Group 4 elements such as titanium (Ti), zirconium (Zr), hafnium (Hf);
Periodic Table Group 5 elements such as vanadium (V), niobium (Nb), tantalum (Ta);
Periodic Table Group 6 elements such as chromium (Cr), molybdenum (Mo), tungsten (W);
Periodic Table Group 7 elements such as manganese (Mn), technetium (Tc), rhenium (Re);
Periodic Table Group 8 elements such as iron (Fe), ruthenium (Ru), osmium (Os);
Periodic Table Group 9 elements such as cobalt (Co), rhodium (Rh), iridium (Ir);
Periodic Table Group 10 elements such as nickel (Ni), palladium (Pd), platinum (Pt);
Periodic Table Group 11 elements such as copper (Cu), silver (Ag), gold (Au);
Periodic Table Group 12 elements such as zinc (Zn), cadmium (Cd), mercury (Hg);
Periodic Table Group 13 elements such as aluminum (Al), gallium (Ga), indium (In);
Group 14 elements of the periodic table such as silicon (Si), germanium (Ge), tin (Sn) and lead (Pb) can be mentioned.
Materials for the inorganic fine particles include magnesium oxide (MgO), magnesium hydroxide (Mg(OH) ₂ ), calcium oxide (CaO), calcium hydroxide (Ca(OH) ₂ ), aluminum oxide (Al ₂ O ₃ ), Aluminum hydroxide (Al(OH) ₃ ), aluminum hydroxide oxide (AlO(OH)), titanium dioxide (TiO ₂ ), barium titanate (BaTiO ₃ ), manganese oxide (II, III) (Mn ₃ O ₄ ) , iron oxide (II, III) (Fe ₃ O ₄ ), iron oxide (III) (Fe ₂ O ₃ ), iron hydroxide (FeO(OH)), nickel oxide (II) (NiO), zinc oxide (II ) (ZnO), yttrium (III) oxide (Y ₂ O ₃ ), zirconium dioxide (ZrO ₂ ), calcium oxide-stabilized zirconium dioxide, yttrium oxide-stabilized zirconium dioxide, zirconium tungstate (ZrW ₂ O ₈ ), tungsten oxide (VI) (WO ₃ ), cerium oxide (IV) (CeO ₂ ), and ITO. Among these, zirconium dioxide (ZrO ₂ ) and titanium dioxide (TiO ₂ ) are particularly preferred.

The "average particle diameter" of the inorganic fine particles is "1 nm or more and less than 100 nm", preferably 5 nm or more, preferably 50 nm or less, more preferably 35 nm or less. When the average particle size of the inorganic fine particles is 1 nm or more, the particle shape is uniform and highly dispersible.
Incidentally, the "average particle size" of the inorganic fine particles is obtained by measuring the particle size length of any 200 or more particles from a transmission electron microscope (TEM) at a magnification of 30,000 to 200,000 times, and measuring the average value. It means a numerical value obtained from

The “specific surface area” of the inorganic fine particles is 1 m ² /g or more and less than 3,000 m ² /g, preferably 15 m ² /g or more, more preferably 20 m ² /g or more, and preferably 500 m ² /g. It is below. If the specific surface area is less than 1 ^{m 2} /g, the particles will have a large particle size, resulting in poor transparency when dispersed in a solvent-free organic compound. If it is large, the particle size is small, the dispersibility is poor due to aggregation, and the filling property when dispersed in a solventless organic compound is poor.
The "specific surface area" of the inorganic fine particles means the numerical value of the measurement result by the BET method when nitrogen gas adsorption is performed at liquid nitrogen temperature.

The inorganic fine particles are preferably metal oxides having a refractive index of 1.5 or more. The refractive index of the inorganic fine particles is more preferably 1.6 or higher, more preferably 2.0 or higher.

式（Ａ－１）で表される化合物及び式（Ａ－２）で表される化合物は、加水分解等の反応性を有する反応性官能基を含む、いわゆる「シランカップリング剤」であり、式（Ａ－１）で表される化合物は１つのシリル基を、式（Ａ－２）で表される化合物は２～１０のシリル基を有する化合物である。
また、式（Ａ－１）で表される化合物は、下記式（Ａ－１－１）～（Ａ－１－４）の何れかで表される化合物をまとめた記載である。

また、式（Ａ－２）で表される化合物は、下記式（Ａ－２－１－１）で表される化合物、下記式（Ａ－２－２－１）で表される化合物等をまとめた記載である。

The coating agent is any one of the following formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2) Although it is at least one of the represented compounds and salts thereof, the specific kind is not particularly limited and can be appropriately selected according to the intended coated inorganic fine particles. Hereinafter, “represented by any of the formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2) “Compounds” will be described in detail.

The compound represented by formula (A-1) and the compound represented by formula (A-2) contain a reactive functional group having reactivity such as hydrolysis, and are so-called "silane coupling agents", The compound represented by formula (A-1) has one silyl group, and the compound represented by formula (A-2) has 2 to 10 silyl groups.
Further, the compound represented by the formula (A-1) is a collective description of the compounds represented by any one of the following formulas (A-1-1) to (A-1-4).

Further, the compound represented by the formula (A-2) includes a compound represented by the following formula (A-2-1-1), a compound represented by the following formula (A-2-2-1), and the like. This is a summary description.

The compound represented by the formula (B-1) and the compound represented by the formula (B-2) are so-called "titanate coupling agents" containing a reactive functional group having reactivity such as hydrolysis, The compound represented by formula (B-1) has one titanate structure, and the compound represented by formula (B-2) has two titanate structures.
The compound represented by formula (C) is a so-called "aluminate coupling agent" containing a reactive functional group having reactivity such as hydrolysis.

The compound represented by formula (D-1) and the compound represented by formula (D-2) are "organic acids" having a carboxyl group, and the compound represented by formula (D-1) is one A compound represented by formula (D-2) as a carboxyl group is a compound having 2 to 10 carboxyl groups.
Further, the compound represented by the formula (D-2) is a summary description of the compound represented by the following formula (D-2-1), the compound represented by the following formula (D-2-2), and the like. be.

R ¹ in formulas (A-1) and (A-2) each independently represents a “hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom”, "Hydrogen group" may have a branched structure, a cyclic structure, and a carbon-carbon unsaturated bond (carbon-carbon double bond, carbon-carbon triple bond), saturated hydrocarbon group, unsaturated carbon It may be a hydrogen group, an aromatic hydrocarbon group, or the like.
Further, the phrase "may contain a heteroatom" means that the hydrogen atoms of the hydrocarbon group are substituted with a heteroatom, i.e., a monovalent functional group containing a nitrogen atom, an oxygen atom, a sulfur atom, a halogen atom, etc. In addition, it means that the carbon atoms inside the carbon skeleton of the hydrocarbon group may be substituted with a divalent or higher functional group (linking group) including a nitrogen atom, an oxygen atom, a sulfur atom, a halogen atom, etc. do.
The number of carbon atoms in the hydrocarbon group for R ¹ is usually 15 or less, preferably 10 or less, more preferably 8 or less, and when R ¹ is an aromatic hydrocarbon group, the number of carbon atoms is usually 6 or more. .
Functional groups and linking groups contained in R ¹ include amino group (-N<), isocyanate group (-NCO), oxa group (-O-), carbonyl group (-C(=O)-), epoxy group , mercapto group (thiol group, -SH), thia group (-S-), fluoro group (fluorine atom, -F), chloro group (chlorine atom, -Cl), bromo group (bromine atom, -Br), iodine groups (iodine atom, -I) and the like.
R ¹ includes a methyl group (--CH ₃ , --Me), an ethyl group (--C ₂ H ₅ , --Et), an n-propyl group ( ^-n C ₃ H ₇ , ^--n Pr) and an i-propyl group. (- ⁱ C ₃ H ₇ , - ⁱ Pr), n-butyl group (- ⁿ C ₄ H ₉ , - ⁿ Bu), t-butyl group (- ^t C ₄ H ₉ , - ^t Bu), n-pentyl group (- ⁿ C ₅ H ₁₁ ), n-hexyl group (- ⁿ C ₆ H ₁₃ , - ⁿ Hex), cyclohexyl group (- ^c C ₆ H ₁₁ , -Cy), allyl group (-CH ₂ CH=CH ₂ ), vinyl group (-CH=CH ₂ ), phenyl group (-C ₆ H ₅ , -Ph), 3-glycidoxypropyl group, 3-methacryloxypropyl group, 3-acryloxypropyl group, N- 2-(aminoethyl)-3-aminopropyl group and the like.

"R ² is a j-valent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom" or "j-valent (poly) having 1 to 20 silicon atoms" in formula (A-2) "siloxy group", "optionally containing a heteroatom" and "hydrocarbon group" are the same as those described above, and "j-valent hydrocarbon group" has j bonding sites. It means that it is a hydrocarbon group having. Further, the “(poly)siloxy group” means a siloxy group having 1 silicon atom or a polysiloxy group having 2 to 20 silicon atoms, and —OSi means a (poly)siloxy group attached as The "j-valent (poly)siloxy group" means a (poly)siloxy group having j bonding sites.
The number of carbon atoms in the hydrocarbon group for R ² is usually 15 or less, preferably 10 or less, more preferably 8 or less, and when R ² is an aromatic hydrocarbon group, the number of carbon atoms is usually 6 or more. .
The number of silicon atoms in the (poly)siloxy group of R ² is usually 15 or less, preferably 10 or less, more preferably 8 or less. In addition, the number of carbon atoms in the hydrocarbon group contained in the (poly)siloxy group is usually 15 or less, preferably 10 or less, more preferably 8 or less as the number of carbon atoms in one hydrocarbon group. The hydrogen group usually has 6 or more carbon atoms.
Functional groups and linking groups contained in R ² include oxa group (-O-), carbonyl group (-C(=O)-), epoxy group, mercapto group (thiol group, -SH), thia group (- S—), fluoro group (fluorine atom, —F), chloro group (chlorine atom, —Cl), bromo group (bromine atom, —Br), iodine group (iodine atom, —I), and the like.
R ² includes a methylene group (-CH ₂ -), an ethylene group (-C ₂ H ₄ -), an n-propylene group (- ⁿ C ₃ H ₆ -), an i-propylene group (- ⁱ C ₃ H ₆ -), n-butylene group (- ⁿ C ₄ H ₈ -), n-pentylene group (- ⁿ C ₅ H ₁₀ -), n-hexylene group (- ⁿ C ₆ H ₁₂ -), phenylene group (-C ₆ H ₄ —), methine group (—CH<), dimethylsiloxy group (—OSi(CH ₃ ) ₂ O—), tetramethyldisiloxy group (—OSi(CH ₃ ) ₂ OSi(CH ₃ ) ₂ O— ) and the like.

Ｒ^７の炭化水素基の炭素原子数は、通常１１以上であり、通常２５以下、好ましくは２０以下である。
Ｒ^７に含まれる官能基や連結基としては、オキサ基（－Ｏ－）、カルボニル基（－Ｃ（＝Ｏ）－）、メルカプト基（チオール基、－ＳＨ）、チア基（－Ｓ－）、フルオロ基（フッ素原子，－Ｆ）、クロロ基（塩素原子，－Ｃｌ）、ブロモ基（臭素原子，－Ｂｒ）、ヨード基（ヨウ素原子，－Ｉ）等が挙げられる。
Ｒ^７としては、ｎ－ウンデシル基（－^ｎＣ_１１Ｈ_２３）、ｎ－ドデシル基（－^ｎＣ_１２Ｈ_２５）、ｎ－トリデシル基（－^ｎＣ_１３Ｈ_２７）、ｎ－テトラデシル基（－^ｎＣ_１４Ｈ_２９）、ｎ－ペンタデシル基（－^ｎＣ_１５Ｈ_３１）、ｎ－ヘキサデシル基（－^ｎＣ_１６Ｈ_３３）等が挙げられる。R ³ in formulas (B-1) and (B-2) and R ⁴ in formula (C) are each independently represented by any of the following formulas (bc-1) to (bc-6) represented structure”, and R ⁷ in formulas (bc-1) and (bc-2) is each independently a “hydrocarbon group having 11 to 30 carbon atoms which may contain a heteroatom” However, the terms “optionally containing a heteroatom” and “hydrocarbon group” have the same meanings as those described above.

The number of carbon atoms in the hydrocarbon group for ^R7 is usually 11 or more, and usually 25 or less, preferably 20 or less.
Functional groups and linking groups contained in R ⁷ include an oxa group (-O-), a carbonyl group (-C(=O)-), a mercapto group (thiol group, -SH), and a thia group (-S-). , fluoro group (fluorine atom, -F), chloro group (chlorine atom, -Cl), bromo group (bromine atom, -Br), iodine group (iodine atom, -I) and the like.
R ⁷ includes n-undecyl group (- ⁿ C ₁₁ H ₂₃ ), n-dodecyl group (- ⁿ C ₁₂ H ₂₅ ), n-tridecyl group (- ⁿ C ₁₃ H ₂₇ ), n-tetradecyl group (- ⁿ C ₁₄ H ₂₉ ), n-pentadecyl group (- ⁿ C ₁₅ H ₃₁ ), n-hexadecyl group (- ⁿ C ₁₆ H ₃₃ ), and the like.

Each R ⁸ in formula (bc-3) independently represents a “hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom”, but “a hydrocarbon group which may contain a heteroatom "good" and "hydrocarbon group" are synonymous with those described above.
The number of carbon atoms in the hydrocarbon group for R ⁸ is usually 25 or less, preferably 20 or less, more preferably 10 or less, and when R ⁸ is an aromatic hydrocarbon group, the number of carbon atoms is usually 6 or more. .
Functional groups and linking groups contained in R ⁸ include an oxa group (-O-), a carbonyl group (-C(=O)-), a mercapto group (thiol group, -SH), and a thia group (-S-). , fluoro group (fluorine atom, -F), chloro group (chlorine atom, -Cl), bromo group (bromine atom, -Br), iodine group (iodine atom, -I) and the like.
R ⁸ includes a methyl group (--CH ₃ , --Me), an ethyl group (--C ₂ H ₅ , --Et), an n-propyl group ( ^-n C ₃ H ₇ , ^--n Pr) and an i-propyl group. (- ⁱ C ₃ H ₇ , - ⁱ Pr), n-butyl group (- ⁿ C ₄ H ₉ , - ⁿ Bu), t-butyl group (- ^t C ₄ H ₉ , - ^t Bu), n-pentyl group (- ⁿ C ₅ H ₁₁ ), n-hexyl group (- ⁿ C ₆ H ₁₃ , - ⁿ Hex), cyclohexyl group (- ^c C ₆ H ₁₁ , -Cy), phenyl group (-C ₆ H ₅ , -Ph) and the like.

R ⁹ in formulas (bc-4) to (bc-6) each independently represents a “hydroxyl group”, an “alkoxy group having 1 to 20 carbon atoms which may contain a heteroatom”, a “heteroatom A hydrocarbon group having 1 to 20 carbon atoms that may contain ", or a "hydrogen atom", but "optionally containing a heteroatom" and "hydrocarbon group" are the same as those described above. Synonymous. Further, the hydrocarbon group in the "alkoxy group" may have a branched structure, a cyclic structure, and a carbon-carbon unsaturated bond (carbon-carbon double bond, carbon-carbon triple bond). Any of a hydrocarbon group, an unsaturated hydrocarbon group, an aromatic hydrocarbon group and the like may be used.
The number of carbon atoms in the alkoxy group for R ⁹ is usually 15 or less, preferably 10 or less, and when the hydrocarbon group of the alkoxy group for R ⁹ is an aromatic hydrocarbon group, the number of carbon atoms is usually 6 or more. .
The number of carbon atoms in the hydrocarbon group for R ⁹ is usually 15 or less, preferably 10 or less, and when the hydrocarbon group for R ⁹ is an aromatic hydrocarbon group, the number of carbon atoms is usually 6 or more.
R ⁹ includes a hydroxyl group (--OH), a methoxy group (--OCH ₃ , --OMe), an ethoxy group (--OC ₂ H ₅ , --OEt), an n-propoxy group (--O ⁿ C ₃ H ₇ , -- O ⁿ Pr), i-propoxy group (—O ⁱ C ₃ H ₇ , —O ⁱ Pr), n-butoxy group (—O ⁿ C ₄ H ₉ , —O ⁿ Bu), t-butoxy group (—O ^t C ₄ H ₉ , —O ^t Bu), phenoxy group (—OC ₆ H ₅ , —OPh), methyl group (—CH ₃ , —Me), ethyl group (—C ₂ H ₅ , —Et), n _-propyl group ( _-nC3H7 , ^-nPr ), ⁱ _- propyl group ⁽ _-iC3H7 , ^-iPr ), ⁿ -butyl group _{( -nC4H9} , ^-nBu ), t-butyl group (- ^t C ₄ H ₉ , - ^t Bu), n-pentyl group (- ⁿ C ₅ H ₁₁ ), n-hexyl group (- ⁿ C ₆ H ₁₃ ,- ⁿ Hex), cyclohexyl group (- ^-c C ₆ H ₁₁ , -Cy), phenyl group (-C ₆ H ₅ , -Ph), hydrogen atom and the like.

Each R ⁵ in formula (D-1) independently represents a “hydrocarbon group having 4 to 30 carbon atoms which may contain a heteroatom”, but “a hydrocarbon group which may contain a heteroatom "good" and "hydrocarbon group" are synonymous with those described above.
The number of carbon atoms in the hydrocarbon group for R ⁵ is usually 25 or less, preferably 20 or less, more preferably 10 or less, and when R ⁵ is an aromatic hydrocarbon group, the number of carbon atoms is usually 6 or more. .
Functional groups and linking groups contained in R ⁵ include an oxa group (-O-), a carbonyl group (-C(=O)-), a mercapto group (thiol group, -SH), and a thia group (-S-). , fluoro group (fluorine atom, -F), chloro group (chlorine atom, -Cl), bromo group (bromine atom, -Br), iodine group (iodine atom, -I) and the like.
R ⁵ includes n-butyl group (- ⁿ C ₄ H ₉ , - ⁿ Bu), t-butyl group (- ^t C ₄ H ₉ , - ^t Bu), n-pentyl group (- ⁿ C ₅ H ₁₁ ), ⁿ _- hexyl group ( _-nC6H13 , _-nHex ), cyclohexyl group ( ^-cC6H11 , ^-Cy ), phenyl group _{( -C6H5} , _-Ph ), and the like.

R ⁶ in formula (D-2) represents “an n-valent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom”, but “an n-valent hydrocarbon group which may contain a heteroatom and "hydrocarbon group" are the same as those described above, and "n-valent hydrocarbon group" means a hydrocarbon group having n bonding sites.
The number of carbon atoms in the hydrocarbon group for R ⁶ is usually 15 or less, preferably 10 or less, more preferably 8 or less, and when R ⁶ is an aromatic hydrocarbon group, the number of carbon atoms is usually 6 or more. .
Functional groups and linking groups contained in R ⁶ include oxa group (-O-), carbonyl group (-C(=O)-), thia group (-S-), fluoro group (fluorine atom, -F). , chloro group (chlorine atom, —Cl), bromo group (bromine atom, —Br), iodine group (iodine atom, —I) and the like.
R ⁶ includes methylene group (-CH ₂ -), ethylene group (-C ₂ H ₄ -), n-propylene group (- ⁿ C ₃ H ₆ -), i-propylene group ( ^-i C ₃ H ₆ -), n-butylene group (- ⁿ C ₄ H ₈ -), n-pentylene group (- ⁿ C ₅ H ₁₀ -), n-hexylene group (- ⁿ C ₆ H ₁₂ -), phenylene group (-C ₆ H ₄ -) and the like.

X ¹ in formulas (A-1) and (A-2) each independently represents an “alkoxy group having 1 to 10 carbon atoms”, a “hydrogen atom”, a “chlorine atom”, a “bromine atom”, or Although "iodine atom" is represented, "alkoxy group" has the same meaning as described above.
The number of carbon atoms in the alkoxy group of X ¹ is usually 8 or less, preferably 6 or less, more preferably 3 or less, and when the hydrocarbon group of the alkoxy group of X ¹ is an aromatic hydrocarbon group, the number of carbon atoms is , usually 6 or more.
X ¹ includes a methoxy group (--OCH ₃ , --OMe), an ethoxy group (--OC ₂ H ₅ , --OEt), an n-propoxy group (--O ⁿ C ₃ H ₇ , --O ⁿ Pr), i- propoxy group (-O ⁱ C ₃ H ₇ , -O ⁱ Pr), n-butoxy group (-O ⁿ C ₄ H ₉ , -O ⁿ Bu), t-butoxy group (-O ^t C ₄ H ₉ ,- O ^t Bu), phenoxy group (--OC ₆ H ₅ , --OPh), hydrogen atom, chlorine atom, bromine atom and iodine atom. Among these, alkoxy groups such as a methoxy group and an ethoxy group are preferable. If X1 is ^an alkoxy group, the reaction will produce a volatile organic compound such as methanol or ethanol, and the effects of the present invention can be utilized more effectively.

Ｘ^２及びＸ^３のアルコキシ基とアシロキシ基の炭素原子数は、通常８以下、好ましくは６以下、より好ましくは３以下であり、Ｘ^２及びＸ^３のアルコキシ基とアシロキシ基の炭化水素基が芳香族炭化水素基の場合の炭素原子数は、通常６以上である。
Ｘ^２及びＸ^３に含まれる官能基や連結基としては、オキサ基（－Ｏ－）、カルボニル基（－Ｃ（＝Ｏ）－）、チア基（－Ｓ－）、フルオロ基（フッ素原子，－Ｆ）、クロロ基（塩素原子，－Ｃｌ）、ブロモ基（臭素原子，－Ｂｒ）、ヨード基（ヨウ素原子，－Ｉ）等が挙げられる。
Ｘ^２及びＸ^３としては、メトキシ基（－ＯＣＨ_３，－ＯＭｅ）、エトキシ基（－ＯＣ_２Ｈ_５，－ＯＥｔ）、ｎ－プロポキシ基（－Ｏ^ｎＣ_３Ｈ_７，－Ｏ^ｎＰｒ）、ｉ－プロポキシ基（－Ｏ^ｉＣ_３Ｈ_７，－Ｏ^ｉＰｒ）、ｎ－ブトキシ基（－Ｏ^ｎＣ_４Ｈ_９，－Ｏ^ｎＢｕ）、ｔ－ブトキシ基（－Ｏ^ｔＣ_４Ｈ_９，－Ｏ^ｔＢｕ）、フェノキシ基（－ＯＣ_６Ｈ_５，－ＯＰｈ）、アセチル基、アセチルアセトナート基、塩素原子、臭素原子、ヨウ素原子が挙げられる。この中でも、メトキシ基、エトキシ基等のアルコキシ基、アセチル基、アセチルアセトナート基等のアシロキシ基が好ましい。Ｘ^１がアルコキシ基やアシロキシ基であると、反応させることによってメタノール、エタノール、アセチルアセトン等の揮発性有機化合物が生成することになり、本発明の効果をより有効に活用することができる。X ² and X ³ in formulas (B-1), (B-2), and (C) each independently represent an “alkoxy group having 1 to 10 carbon atoms” or “a heteroatom-containing "Good acyloxy group having 1 to 10 carbon atoms", "chlorine atom", "bromine atom" or "iodine atom", but "optionally containing a heteroatom" and "alkoxy group" is synonymous with Further, "acyloxy group" means a structure represented by -OC(=O)R, and the hydrocarbon group in the acyloxy group includes a branched structure, a cyclic structure, and a carbon-carbon unsaturated bond (carbon-carbon two double bond, carbon-carbon triple bond), and may be any of a saturated hydrocarbon group, an unsaturated hydrocarbon group, an aromatic hydrocarbon group, and the like. Furthermore, the structure in which "the alkoxy groups and/or acyloxy groups of X ² and X ³ are bonded to other alkoxy groups and/or acyloxy groups of X ² and X ³ , respectively, to form a cyclic structure" refers to an alkoxy It means that the hydrocarbon groups of groups and acyloxy groups are bonded together to form a cyclic structure (see below). The number of carbon atoms in the hydrocarbon group forming the cyclic structure is 1 to 10 in total.

The number of carbon atoms in the alkoxy and acyloxy groups of X ² and X ³ is usually 8 or less, preferably 6 or less, more preferably 3 or less, and the hydrocarbon groups of the alkoxy and acyloxy groups of X ² and X ³ are The number of carbon atoms in the aromatic hydrocarbon group is usually 6 or more.
Functional groups and linking groups contained in X ² and X ³ include oxa group (-O-), carbonyl group (-C(=O)-), thia group (-S-), fluoro group (fluorine atom, -F), chloro group (chlorine atom, -Cl), bromo group (bromine atom, -Br), iodo group (iodine atom, -I) and the like.
X ² and X ³ include a methoxy group (--OCH ₃ , --OMe), an ethoxy group (--OC ₂ H ₅ , --OEt) and an n-propoxy group (--O ⁿ C ₃ H ₇ , --O ⁿ Pr). , i-propoxy group (-O ⁱ C ₃ H ₇ , -O ⁱ Pr), n-butoxy group (-O ⁿ C ₄ H ₉ , -O ⁿ Bu), t-butoxy group (-O ^t C ₄ H ₉ , —O ^t Bu), phenoxy group (—OC ₆ H ₅ , —OPh), acetyl group, acetylacetonato group, chlorine atom, bromine atom, and iodine atom. Among these, an alkoxy group such as a methoxy group and an ethoxy group, and an acyloxy group such as an acetyl group and an acetylacetonate group are preferable. If X1 is ^an alkoxy group or an acyloxy group, the reaction will produce a volatile organic compound such as methanol, ethanol, acetylacetone, etc., and the effects of the present invention can be utilized more effectively.

The coating agent is represented by any of formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2). and at least one of the compounds and salts thereof, but the “salt thereof” refers to formulas (A-1), (A-2), (B-1), (B-2), (C), ( D-1) and means a salt formed by a compound represented by (D-2). For example, compounds represented by formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2) has a basic functional group such as an amino group, it may combine with hydrogen chloride (HCl) to form a hydrochloride, and the organic acid such as the compound represented by the formula (D-1) is an alkali metal may form metal salts with cations such as A coating agent may be such a salt.

Examples of the compound represented by formula (A-1) and the compound represented by formula (A-2) include vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, 2-(3,4-epoxycyclohexyl ) Ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryl trimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3 -aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1 ,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3-ureidopropyltri Ethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane silane, propyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, phenyltrimethoxysilane, trifluoropropyltrimethoxysilane, cyclohexylmethyldimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, phenyltrimethoxysilane ethoxysilane, hexyltriethoxysilane, hexamethyldisilazane, and the like.

Examples of the compound represented by formula (B-1) and the compound represented by formula (B-2) include tetraisopropyl titanate, tetra-n-butyl titanate, titanium butoxide dimer, tetra-2-ethylhexyl titanate, and titanium di-2. - ethylhexoxybis(2-ethyl-3-hydroxyhexoxide), isopropyl triisostearoyl titanate, isopropyl tris(dioctylpyrophosphate) titanate, bis(dioctylpyrophosphate)oxyacetate titanate, tris(dioctylpyrophosphate)ethylene titanate, isopropyl dioctylpyrophosphate titanate, isopropyl tris(dodecylbenzenesulfonyl) titanate, tetraisopropylbis(dioctylphosphite) titanate, tetraoctylbis(ditridecylphosphite) titanate, tetra(2,2-diallyloxymethyl-1- butyl)bis(ditridecyl)phosphite titanate and the like.

Examples of compounds represented by formula (C) include alkylacetoacetate aluminum diisopropylate, aluminum trisecondary butoxide, aluminum tris(acetylacetonate), aluminum bisethylacetoacetate monoacetylacetonate, aluminum tris(ethylacetoacetate). , aluminum alkylacetoacetate diisopropylate, and the like.

Examples of the compound represented by formula (D-1) and the compound represented by formula (D-2) include butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, Examples include organic acids such as tetradecanoic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, oleic acid, vaccenic acid, linoleic acid, and linolenic acid.

The coated inorganic fine particles of the present invention are coated inorganic fine particles having a coating layer obtained by reacting the surface of the inorganic fine particles with a coating agent. On the other hand, it is usually 3 parts by weight or more, preferably 5 parts by weight or more, and usually 100 parts by weight or less, preferably 55 parts by weight or less. If the amount of the coating agent added is less than 3 parts by weight, the coated inorganic fine particles are difficult to uniformly disperse in the solvent-free organic compound and contain secondary agglomerated particles. When the coating amount of the organic compound is more than 100 parts by weight, it is possible to uniformly disperse the organic compound, but the ratio of the coating agent becomes larger than that of the inorganic fine particles, and the original function of the inorganic fine particles is deteriorated.

The coating layer of the coated inorganic fine particles of the present invention means a layer formed by reacting (surface-modifying) the coating agent on the surface of the inorganic fine particles, or by reacting the coating agents with each other and adsorbing to the surface of the inorganic fine particles. , its composition is derived from the type of coating.
The content of the coating layer in the coated inorganic fine particles of the present invention (when the entire coated inorganic fine particles is 100% by weight) is usually 1% by weight or more, preferably 3% by weight or more, and usually 45% by weight or less, preferably 30% by weight or less. If the coating layer is less than 1% by weight, it is difficult for the coated inorganic fine particles to disperse uniformly in the solventless organic compound, and secondary agglomerated particles are included. If the coating layer is larger than 45% by weight, it is possible to uniformly disperse the particles, but the ratio of the coating layer to the inorganic fine particles is increased, and the original function of the inorganic fine particles is deteriorated.
The content of the coating layer can be determined by quantifying the amounts of silicon element, titanium element, aluminum element, organic group, etc. contained in the coating layer by various elemental analyses.

The content of volatile organic compounds in the coated inorganic fine particles of the present invention is less than 100 ppm. It means all the organic compounds that volatilize when the coated inorganic fine particles are heated at 120° C. for 10 minutes, and is the amount measured as the toluene-equivalent volume concentration of all the volatile organic compounds generated.
Volatile organic compounds include alcohols such as methanol, ethanol, n-propanol, and i-propanol generated by decomposition of coating agents; hydrocarbon solvents such as hexane, cyclohexane, toluene, xylene, ethylbenzene, and decane; dichloromethane and trichlorethylene. Ether solvents such as tetrahydrofuran; Ester solvents such as ethyl acetate;

The content of volatile organic compounds is usually 1 ppm or more, preferably less than 80 ppm, more preferably less than 50 ppm. If the content of the volatile organic compound is 100 ppm or more, outgassing is generated when the nanocomposite material is cured, which adversely affects the life of the light emitting device in applications such as organic EL and LED. In addition, a drying process or the like is required to remove volatile organic compounds during molding, which leads to an increase in manufacturing costs.
The content of volatile organic compounds can be measured using a commercially available volatile organic compound measuring device.

The coated inorganic fine particles of the present invention are preferably metal oxides having a refractive index of 1.5 or more. The refractive index of the coated inorganic fine particles of the present invention is preferably 1.5 or higher, more preferably 1.6 or higher, and still more preferably 2.0 or higher. When used for transparent nanocomposite materials such as optical members such as liquid crystal displays, organic ELs, LEDs, and lenses, if the refractive index is less than 1.5, such as _SiO2 , it is equivalent to or equal to the refractive index of organic compounds such as resins. Since it becomes low, it is difficult to adjust the refractive index.

<Method for producing coated inorganic fine particles>
The production method of the coated inorganic fine particles of the present invention is not particularly limited, but a preferred production method includes the following steps (1) to (4). A method for producing coated inorganic fine particles, which includes steps (1) to (4), is also an aspect of the present invention.
(1) A preparatory step of preparing an aqueous solution in which metal hydroxides and/or condensates of metal hydroxides are dissolved and/or dispersed (hereinafter sometimes abbreviated as "preparatory step").
(2) A hydrothermal reaction step of generating inorganic fine particles by hydrothermally reacting the aqueous solution prepared in the preparation step at a temperature of 200 ° C. or higher, a pressure of 20 MPa or higher, and a reaction time of 0.1 minute or longer (hereinafter referred to as "hydrothermal reaction step ” may be abbreviated.)
(3) an isolation step of isolating the inorganic fine particles produced in the hydrothermal reaction step (hereinafter sometimes abbreviated as “isolation step”);
(4) the inorganic fine particles isolated in the isolation step and the formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2) in a water solvent reacting at least one of the compounds (hereinafter sometimes abbreviated as "coating step")
The “preparation step”, the “hydrothermal reaction step”, the “isolation step”, the “coating step” and the like will be described in detail below.

(Preparation process)
In the preparation step, an aqueous solution (hereinafter referred to as It may be abbreviated as "aqueous solution of metal hydroxide, etc."). The term "condensate" means a precursor in which metal hydroxides are condensed with each other to form an MOM (metal atom-oxygen atom-metal atom) bond. Moreover, the "aqueous solution" is not limited to a state in which metal hydroxides and the like are uniformly dispersed (dissolved) at the molecular level, but also includes a state of suspension (slurry).
That is, in the aqueous solution, even if the metal hydroxide is dissolved in the state of a monomer, the precursor of the inorganic fine particles is in a state in which the metal hydroxide is aggregated (hereinafter referred to as "aggregate of metal hydroxide"). It may be abbreviated as ), the metal hydroxide condensate may be dispersed (suspended), or they may be mixed. means.
The type of metal element such as a metal hydroxide should be selected according to the type of the target inorganic fine particles. The above metal elements should be selected.
Aggregates of metal hydroxides and condensates of metal hydroxides may be crystalline or amorphous (amorphous substances), but they are homogeneously nucleated and grained. It is preferably amorphous from the viewpoint of growth. When the metal hydroxide aggregate and the metal hydroxide condensate have crystallinity, the average particle size is preferably 0.1 μm or less. If the particle size exceeds 0.1 μm or less, it is difficult to uniformly disperse the metal hydroxide or the like, and the particles settle in the hydrothermal reaction step, resulting in a non-uniform reaction. Therefore, it is difficult to obtain highly dispersible and highly crystalline inorganic fine particles. In addition, when the metal hydroxide or the like settles, clogging is likely to occur in the reactor.

The concentration of the metal oxide or the like in the aqueous solution of the metal hydroxide or the like is usually 0.01 mol/L or more, preferably 0.05 mol/L or more, 0.1 mol/L or more, as the substance amount of the metal element (main component element). L or more, usually 1.0 mol/L or less, preferably 0.5 mol/L or less. The concentration of the metal hydroxide and/or the condensate of the metal hydroxide greatly affects the viscosity of the aqueous solution, and when it exceeds 1.0 mol/L, the product tends to clog the reactor due to the high viscosity, This leads to lower yield and contamination.

A method for preparing an aqueous solution of a metal hydroxide or the like is not particularly limited, but examples thereof include a method of hydrolyzing a raw material compound containing the target metal element in an acidic or basic aqueous solution. In particular, a method of hydrolyzing by adding a base to an aqueous solution in which the raw material compound is dissolved and/or dispersed (hereinafter sometimes abbreviated as "aqueous solution of raw material compound") is preferred. When the raw material compound is an acidic compound having Lewis acidity or the like, it is usually "neutralized" by adding a base to the aqueous solution.
The raw material compound is not particularly limited as long as it contains the target metal element and produces a metal hydroxide or the like by hydrolysis, but it is a metal chloride, metal sulfate, metal nitrate, or the like that includes the target metal element. metal hydroxides, metal oxides and the like having different compositions from the metal salts, metal alkoxides and metal hydroxides of
The concentration of the raw material compound in the aqueous solution can be appropriately selected according to the type of metal element, etc., but is usually 0.05 mol/L or more, preferably 0.1 mol/L or more, and usually 3.0 mol/L. Below, preferably 0.5 mol/L or less.
Bases include sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonia ( _NH3 ), ammonium hydrogen carbonate ( _NH4HCO3 ), sodium carbonate _{( Na2CO3} ) _, potassium carbonate _{( K2CO3} ), sodium hydrogencarbonate (NaHCO ₃ ), potassium hydrogencarbonate (KHCO ₃ ), etc., and two or more of them may be used in combination. The base is preferably dissolved in water and added to the aqueous solution of the raw material compound in the form of a basic aqueous solution (aqueous alkaline solution).
The amount of the basic aqueous solution to be added is preferably such that the pH at the end of the addition is 3.0 to 14.0, more preferably 6.0 to 13.0. The weight ratio of the amount of the basic aqueous solution and the aqueous solution of the raw material compound (former:latter) is preferably 100:1 to 1:100, more preferably 10:1 to 1:10.

A dispersing agent may be added to the liquid phase of the starting compound aqueous solution and/or the basic aqueous solution in order to achieve a uniform state. Dispersants include, for example, surfactants, citric acid, amines, organic solvents, polyethylene glycol (PEG), or organic compounds such as polyvinyl alcohol (PVA). Addition of these dispersants has the effect of improving the dispersibility of the inorganic fine particles, controlling the particle morphology, and increasing the crystallization. Among such dispersants, surfactants are particularly preferable because they can further improve the dispersibility and have a great effect on the uniformity of the particle form. Examples of surfactants that can be used include higher fatty acids and salts thereof, alkyl sulfate ester salts, fatty acid amine compounds, and alkyl sulfosuccinates.
The amount of the dispersant added is usually 0.01% by weight or more, preferably 0.1% by weight or more, and usually 10.0% by weight or less, preferably 5% by weight, based on the theoretical amount of inorganic fine particles to be produced. 0% by weight or less. If the amount of the dispersant added is less than 0.01% by weight, the effect of the dispersant on homogenization of the inorganic alkaline salt aqueous solution or slurry, and on the high dispersibility, high crystallinity, and high uniformity of the inorganic fine particles produced is small. If it exceeds 10.0% by weight, the produced inorganic fine particles tend to aggregate.

(Hydrothermal reaction step)
The hydrothermal reaction step is a step of hydrothermally reacting the aqueous solution prepared in the preparation step at a temperature of 200° C. or higher, a pressure of 20 MPa or higher, and a reaction time of 0.1 minute or longer to generate inorganic fine particles. , a pressure of 20 MPa or more, and a reaction time of 0.1 minute or more”, the inorganic fine particles produced can be produced by conventional solid phase reaction methods, wet reaction methods, gas phase methods, and hydrothermal reaction methods under low temperature and low pressure conditions. Compared to , it has excellent dispersibility in any solvent, uniform particle shape, large specific surface area, and high reactivity of the particle surface.
The temperature of the hydrothermal reaction is 200° C. or higher, preferably 250° C. or higher, and usually 450° C. or lower, preferably 400° C. or lower. The temperature of the hydrothermal reaction varies depending on the microparticles to be produced, but similarly to the pressure, if the temperature is less than 200° C., particle formation is difficult, crystallinity is poor, and impurities derived from raw materials are likely to be incorporated. The upper limit of the temperature is not particularly limited and is limited by the specifications of the apparatus, but if it exceeds 500 ° C. as with the pressure, the product tends to adhere in the reaction tube, resulting in a decrease in yield and contamination. .

The pressure of the hydrothermal reaction is 20 MPa or more, but usually 50 MPa or less, preferably 40 MPa or less. The pressure of the hydrothermal reaction varies depending on the microparticles to be produced, but if the pressure is less than 20 MPa, particle formation is difficult, crystallinity is poor, and impurities derived from raw materials are likely to be incorporated. The upper limit of the pressure is not particularly limited and is limited by the specifications of the apparatus, but if it exceeds 50 MPa, the product tends to adhere in the reaction tube, resulting in a decrease in yield and contamination.

The reaction time of the hydrothermal reaction (residence time in the reactor) is 0.1 minute or more, but usually 60 minutes or less, preferably 30 minutes or less. Although the reaction time varies depending on the microparticles to be produced, if the reaction time is less than 0.1 minute, it is difficult to form particles, the crystallinity is poor, and impurities derived from raw materials are likely to be incorporated.

The hydrothermal reaction step is not particularly limited as long as it satisfies the above conditions, but when producing metal fine particles as inorganic fine particles, for example, the reaction is performed in the presence of a reducing agent such as hydrogen gas, Proceeding the reduction reaction can be mentioned. In addition, various kinds of inorganic fine particles can be produced by appropriately controlling the conditions of the hydrothermal reaction step. In addition, depending on the conditions, the particle shape can be controlled to be spherical, cubic, plate-like, flake-like, needle-like, rod-like, fiber-like, and the like.

(Isolation step)
The isolation step is a step of isolating the inorganic fine particles produced in the hydrothermal reaction step, but the isolation method is not particularly limited, and a known method can be appropriately employed. Usually, the aqueous solution after the hydrothermal step is cooled, the pressure is reduced, and the recovered product is filtered, washed with water, and dried.

(Coating process)
The coating step is a step of reacting the inorganic fine particles isolated in the isolation step with the coating agent in an aqueous solvent. It has the advantage that volatile organic compounds are less likely to remain and that the surface of the inorganic fine particles can be uniformly coated with the coating agent.
The operating method of the coating step is not particularly limited, but usually includes a method of uniformly dispersing inorganic fine particles in an aqueous solvent, adding a coating agent, and heating to the reaction temperature to react.

The amount of the aqueous solvent used in the coating step is such that the concentration of the inorganic fine particles is usually 1% by weight or more, preferably 3% by weight or more, more preferably 5% by weight or more, and is usually 45% by weight or less, preferably 35% by weight or less. , more preferably 25% by weight or less.
In order to uniformly disperse the inorganic fine particles in the water solvent, it is usually preferable to add an acid or a base to adjust the pH. The acid or base is preferably added so that the pH at the time of addition is 1.0 to 14.0, more preferably 3.0 to 10.0.
In order to uniformly disperse the inorganic fine particles in the water solvent, it is preferable to stir the mixture with a dispersing machine such as an ultrasonic homogenizer, planetary ball mill, Henschel mixer, colloid mill, wet jet mill, or wet bead mill.

The amount of the coating agent added is usually 3 parts by weight or more, preferably 5 parts by weight or more, and usually 100 parts by weight or less, preferably 55 parts by weight or less, relative to 100 parts by weight of the inorganic fine particles.

The reaction temperature in the coating step is usually room temperature or higher, preferably 25° C. or higher, and usually 80° C. or lower, preferably 60° C. or lower.
The reaction time (residence time in the reactor) in the coating step is 5 minutes or more, but usually 24 hours or less, preferably 8 hours or less.

The method for producing coated inorganic fine particles of the present invention may include steps other than the above-described preparatory steps, etc. Generally, the suspension that has undergone the coating step is dried at a temperature of 200° C. or less and pulverized. coated inorganic fine particles are obtained.

<Nanocomposite material>
As mentioned above, the coated inorganic fine particles of the present invention are useful for realizing a transparent nanocomposite material. Nanocomposite materials (hereinafter referred to as " may be abbreviated as "the nanocomposite material of the present invention") is also an aspect of the present invention.
The “transparent organic compound” and the like will be described in detail below.

The nanocomposite material of the present invention is a material obtained by dispersing the coated inorganic fine particles of the present invention in a transparent organic compound. Examples of the organic compound include organic solvents; polymerizable monomers and oligomers; Thermoplastic resins such as polystyrene, acrylic, polyvinyl chloride, polycarbonate, nylon, urethane, PBT, PET, and ABS, thermosetting resins such as melamine, phenol, epoxy, urethane, polyimide, diallyl phthalate, unsaturated polyester, furan, and silicone Examples thereof include resins, elastomers, rubbers, radical polymerizable or cationic polymerizable UV-curable resins, visible light-, infrared-, electron-beam-curable resins, and the like. They may be used alone or in combination, and the nanocomposite material can be appropriately selected depending on the application.

The nanocomposite materials of the present invention are preferably "transparent". It should be noted that the term “transparent” means that light in a predetermined wavelength band such as visible light, near-infrared rays, and near-ultraviolet rays can be transmitted. is preferably 85% or more. In applications such as optical members, if the spectral transmittance is less than 65%, it is not preferable because it directly affects the deterioration of the performance of the optical device. In addition, even in applications other than optical members, there is a demand for a uniformly dispersed state of inorganic fine particles with a transmittance of 65% or more.

The content of the coated inorganic fine particles in the nanocomposite material of the present invention is usually 10% by weight or more, preferably 20% by weight or more, and usually 85% by weight or less, preferably 75% by weight or less. When the content of the coated inorganic fine particles is less than 10% by weight, it is difficult to develop the functionality of the inorganic fine particles. If the content of the coated inorganic fine particles is more than 85% by weight, the original functionality of the organic compound cannot be exhibited, and the viscosity of the composite material becomes extremely high, adversely affecting handling during molding.

Ribbon mixers, co-kneaders, extruders, internal mixers, kneaders, pug mills, galacon pounders, augers, pin mixers, rod mixers, sand mills and crutchers are used to uniformly disperse the coated inorganic fine particles of the present invention in organic compounds. , High-speed fluidized mixer, Henschel mixer, Shugi mixer, Simpson mill, Whirlmix, Eirich mill, Universal mixer, Rai kneader, Planetary mixer, 3 roll mill, Taper roll mill, Wet bead mill, Wet jet mill , a dispersing machine such as an ultrasonic homogenizer, a high-speed stirring or pressure emulsifying machine, a stirrer, or a mixer. It is possible to disperse more uniformly by heating or applying vacuum during the dispersion treatment to lower the viscosity or defoam.

Various types of additives may be used alone or in combination in the nanocomposite material of the present invention as required. Additives include heat stabilizers, antioxidants, light stabilizers, weather stabilizers, stabilizers for ultraviolet absorption and near-infrared absorption, lubricants, plasticizers, anti-clouding agents, dispersants, colorants, and antistatic agents. , flame retardants, release agents, curing agents, initiators, and the like.
The shape of the nanocomposite material of the present invention can be appropriately selected from liquid, bulk, film, sheet, thin film, and the like, depending on the application.

The coated inorganic fine particles and the method for producing the same according to the present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[Production Example 1 (zirconia fine particles)]
Using an aqueous solution of zirconium oxychloride as an aqueous solution of zirconium salt and an aqueous solution of sodium hydroxide as an aqueous alkali solution, the amount of Zr is 0.40 mol and the amount of alkali is 0.8 mol [degree of neutralization = alkali amount / (2 × Zr amount) = 1 .0]. Next, an aqueous sodium hydroxide solution was added to the aqueous zirconium salt solution at room temperature in the atmosphere in the raw material tank to prepare an aqueous solution containing amorphous zirconium hydroxide as a reaction precursor. The pH value of the reaction precursor after preparation was 12.5. The prepared reaction precursor was subjected to a hydrothermal reaction in a hydrothermal reactor at a temperature of 300° C., a pressure of 20 MPa, and a residence time of 0.25 minutes, followed by filtration, washing with water and drying to obtain zirconia fine particles.
The obtained zirconia fine particles were evaluated for average particle size and specific surface area. A transmission electron microscope (TEM) photograph (200,000 times) is shown in FIG. The average particle size was 10 nm, the relative standard deviation of the average particle size was 0.20, and the specific surface area was 140 m ² /g. Good uniformity of particle morphology is observed by TEM.

[Production Example 2 (titania fine particles)]
Using an aqueous solution of titanium tetrachloride as an aqueous titanium salt solution and an aqueous sodium hydroxide solution as an alkaline aqueous solution, the amount of Ti is 0.40 mol and the amount of alkali is 1.2 mol [degree of neutralization = alkali amount / (4 × Ti amount) = 1 .0]. Next, an aqueous nitric acid solution was added to the aqueous titanium salt solution at room temperature in the atmosphere in the raw material tank to prepare an amorphous titanium hydroxide-containing aqueous solution as a reaction precursor. The pH value of the reaction precursor after preparation was 5.0. The prepared reaction precursor was subjected to a hydrothermal reaction in a hydrothermal reactor at a temperature of 350° C., a pressure of 20 MPa, and a residence time of 0.25 minutes.
The obtained titania fine particles were evaluated for average particle size and specific surface area. A transmission electron microscope (TEM) photograph (200,000 times) is shown in FIG. The average particle size was 10 nm, the relative standard deviation of the average particle size was 0.24, and the specific surface area was 160 m ² /g. Good uniformity of particle morphology is observed by TEM.

[Preparation of coated inorganic fine particles]
<Examples 1 to 9>
300 g of the zirconia fine particles of Production Example 1 were dispersed in 2700 g of water, and 24 g of acetic acid was added and uniformly dispersed. While stirring this aqueous dispersion, an organosilicon compound was added according to Table 1, and the mixture was stirred at 50° C. for 4 hours. After that, the mixed dispersion was dried at 80° C. to obtain zirconia fine particles coated with an organosilicon compound.

<Example 10>
300 g of the titania fine particles of Production Example 2 were dispersed in 2700 g of water, and 24 g of acetic acid was added and uniformly dispersed. While stirring this aqueous dispersion, an organosilicon compound was added according to Table 1, and the mixture was stirred at 50° C. for 4 hours. After that, the mixed dispersion was dried at 80° C. to obtain fine titania particles coated with the organosilicon compound.

<Comparative Example 1>
300 g of zirconia fine particles of Production Example 1 were uniformly dispersed in 2700 g of ethanol. While stirring this ethanol dispersion, 66.9 g of 3-methacryloxypropyltrimethoxysilane (“A-174” manufactured by Momentive Performance Materials) was added and stirred at 50° C. for 4 hours. After that, the mixed dispersion was dried under reduced pressure at 60° C. to obtain zirconia fine particles coated with an organosilicon compound.

<Comparative Example 2>
300 g of commercially available zirconia fine particles having an average particle diameter of 15 nm and a specific surface area of 90 m ² /g synthesized by a wet method were dispersed in 2700 g of water, and 24 g of acetic acid was added to uniformly disperse. While stirring this aqueous dispersion, 66.9 g of 3-methacryloxypropyltrimethoxysilane (“A-174” manufactured by Momentive Performance Materials) was added and stirred at 50° C. for 4 hours. After that, the mixed dispersion was dried at 80° C. to obtain zirconia fine particles coated with an organosilicon compound.

<Comparative Example 3>
300 g of commercially available zirconia fine particles synthesized by a wet method having an average particle diameter of 15 nm and a specific surface area of 90 m ² /g were uniformly dispersed in 2700 g of ethanol. While stirring this ethanol dispersion, 66.9 g of 3-methacryloxypropyltrimethoxysilane (“A-174” manufactured by Momentive Performance Materials) was added and stirred at 50° C. for 4 hours. After that, the mixed dispersion was dried under reduced pressure at 60° C. to obtain zirconia fine particles coated with an organosilicon compound.

The coated inorganic fine particles obtained in Examples 1 to 10 and Comparative Examples 1 to 3 were subjected to the following property evaluations (3) to (5), and the results are shown in Table 1.
<Evaluation method>
(1) Measurement of average particle size, evaluation of particle shape and uniformity Using a Hitachi High-Technologies transmission electron microscope (H-7600), an image of particles is obtained at a magnification of 30,000 to 200,000 times, and 200 or more The average particle diameter was measured by measuring the long diameter of the particles and obtaining the average value. The particle shape was evaluated by observation of TEM images, and the uniformity was evaluated by the relative standard deviation of the measured values of the average particle size.

(2) Measurement of specific surface area Using coated inorganic fine particles degassed at 150 ° C., using a fully automatic BET specific surface area measuring device (Macsorb HM Model-1210) manufactured by Mountech, BET method from adsorption and desorption of nitrogen gas. to measure the specific surface area.

(3) Measurement of amount of volatile organic compounds S. P. Inc. Volatile organic compound measuring device (VOC-401P) manufactured by Co., Ltd. is used to heat 0.500 g of coated inorganic fine particles at 120 ° C. for 10 minutes. (ppm in terms of toluene) was measured. All volatile organic compounds that volatilize at the heating temperature, including 100 major VOCs indicated by the Ministry of the Environment, were measured.

（（式１）中、Ｗ_Ｃは被覆剤の添加量を、Ｗ_Ｐは無機微粒子量を、Ｍ_Ｃは被覆剤の分子量を、Ｍ_Ｃ’は被覆剤が反応した後の構造の分子量を、ｐは下記式２で示される被覆剤の反応率を表す。）

（（式２）中、Ｃ”_ＸＲＦは被覆剤に含まれるＳｉ又はＴｉ又はＡｌ元素のＸＲＦにおける定量値を、Ｐ_ＸＲＦは原料となる無機微粒子を構成する金属もしくは金属酸化物のＸＲＦにおける定量値を、Ｗ_Ｃは被覆剤の添加量を、Ｗ_Ｐは無機微粒子量を、Ｍ_Ｃは被覆剤の分子量を、Ｍ_Ｃ”は被覆剤に含まれるＳｉ又はＴｉ又はＡｌ元素原子量を表す。）(4) Measurement of Coating Layer Amount in Coated Inorganic Fine Particles Using a fluorescent X-ray spectrometer (S8 TIGER) manufactured by Bruker AXS, the amount of each element in the coated inorganic fine particles was quantified. From the obtained quantitative values, the weight fraction X of the coating layer with respect to the coated inorganic fine particles was calculated based on the following formula 1.

(In (Formula 1), W _C is the amount of the coating agent added, W _P is the amount of the inorganic fine particles, M _C is the molecular weight of the coating agent, and M _C′ is the molecular weight of the structure after the reaction of the coating agent. p represents the reaction rate of the coating material represented by the following formula 2.)

(In (Formula 2), C″ _XRF is the quantitative value of the Si or Ti or Al element contained in the coating agent in XRF, and P _XRF is the quantitative value in XRF of the metal or metal oxide that constitutes the raw material inorganic fine particles. , _WC is the amount of coating agent added, _WP is the amount of inorganic fine particles, M _C is the molecular weight of the coating agent, and M _C” is the atomic weight of Si, Ti or Al element contained in the coating agent.)

(5) Measurement of refractive index of transparent nanocomposite material and coated inorganic fine particles A cured test piece was prepared using a high pressure mercury lamp (Handicure 100). The refractive index of the transparent nanocomposite material was evaluated by measuring the refractive index of this test piece at a temperature of 25° C. and a wavelength of 589 nm using a multi-wavelength Abbe refractometer (DR-M4) manufactured by Atago. Further, the refractive index of the coated inorganic fine particles was calculated from the refractive index of the obtained transparent nanocomposite material and the refractive index of a test piece prepared solely from ethoxylated o-phenylphenol acrylate.

From the results of Examples 1 to 10, in the present invention, by coating the surface of inorganic fine particles synthesized by a hydrothermal reaction under high temperature and high pressure conditions with a coating agent in an aqueous solvent, a coating with a volatile organic compound content of 100 ppm or less can be obtained. Inorganic fine particles could be obtained.
The coated inorganic fine particles of Comparative Examples 1 and 3 are produced by dispersing the inorganic fine particles in an organic solvent to coat the surface, and then removing the organic solvent. Therefore, they contain volatile organic compounds derived from the dispersion medium. Coated inorganic fine particles were obtained. The coated inorganic fine particles of Comparative Example 2 are coated inorganic fine particles surface-coated in an aqueous solvent. Since the reactivity of the coating agent was low, the coated inorganic fine particles contained 100 ppm or more of volatile organic compounds.

[Preparation of transparent nanocomposite material]
<Example 11>
To 100 g of the coated inorganic fine particles described in Example 1, 100 g of ethoxylated-o-phenylphenol acrylate (“NK Ester A-LEN-10” manufactured by Shin-Nakamura Chemical Co., Ltd.), 1-hydroxycyclohexylphenyl ketone (manufactured by BASF “ 6 g of IRGACURE 184”) was added, and dispersion treatment was performed using a high-speed stirrer at 16,000 rpm for 1 hour to obtain a nanocomposite material containing 50% by weight of coated zirconia fine particles. After applying a transparent nanocomposite material containing coated inorganic fine particles to a film thickness of 40 μm on a PET film (“Lumirror T60” manufactured by Toray Industries, Inc., 12 mm × 80 mm × 100 μm), a high-pressure mercury lamp manufactured by Sen Special Light Source Co., Ltd. (Handicure 100 ) was used to prepare a cured test piece. The transmittance of this test piece at a wavelength of 400 nm was measured using a PET film as a reference and a ratio beam ultraviolet-visible spectrophotometer (U-5100) manufactured by Hitachi High-Tech Science Co., Ltd., and was 83.4% T. . In addition, after pouring the obtained nanocomposite material into a PTFE mold with a volume of 15 mm × 30 mm × 0.5 mm, a test piece cured using a high-pressure mercury lamp (Handicure 100) manufactured by Sen Special Light Source Co., Ltd. made. The refractive index of this test piece at a temperature of 25° C. and a wavelength of 589 nm was 1.649 when measured using a multi-wavelength Abbe refractometer (DR-M4) manufactured by Atago Co., Ltd.

<Comparative Example 4>
To 100 g of the coated inorganic fine particles described in Comparative Example 1, 100 g of ethoxylated-o-phenylphenol acrylate (“NK Ester A-LEN-10” manufactured by Shin-Nakamura Chemical Co., Ltd.), 1-hydroxycyclohexylphenyl ketone (manufactured by BASF “ 6 g of IRGACURE 184”) was added, and dispersion treatment was performed using a high-speed stirrer at 16,000 rpm for 1 hour to obtain a nanocomposite material containing 50% by weight of coated zirconia fine particles. The obtained nanocomposite was evaluated for transparency and refractive index in the same manner as in Example 11, and the transmittance at a wavelength of 400 nm was 29.3% T and the refractive index was 1.652.

From the results of Example 11, the coated inorganic fine particles of the present invention have good dispersibility in organic compounds, so that a solvent-free nanocomposite material with high transparency can be obtained.
The nanocomposite material of Comparative Example 4 uses coated inorganic fine particles using commercially available zirconia fine particles synthesized by a wet method. It becomes a nanocomposite material with low transparency.

The coated inorganic fine particles of the present invention can be suitably used for transparent nanocomposite materials used in liquid crystal displays, organic ELs, LEDs, optical members such as lenses, electronic members, coating materials, dental materials, and the like.

Claims (13)

Any one of the following formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2) on the surface of the inorganic fine particles A coated inorganic fine particle having a coating layer obtained by reacting at least one of a compound represented by and a salt thereof,
The inorganic fine particles have an average particle diameter of 1 nm or more and less than 100 nm, and a specific surface area of 1 m ² /g or more and less than 3,000 m ² /g,
Coated inorganic fine particles, characterized in that the content of a volatile organic compound is 89 ppm or less .

(In formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2), R ¹ is is a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, R ² is a j-valent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, or the number of silicon atoms 1 to 20 j-valent (poly)siloxy groups, R ³ and R ⁴ each independently have a structure represented by any one of the following formulas (bc-1) to (bc-6), R ⁵ R 6 is a hydrocarbon group having 4 to 30 carbon atoms which may contain a heteroatom, R ⁶ is an n-valent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, and X ¹ is each X ² and X ³ are each independently an alkoxy group having 1 to 10 carbon atoms, a hydrogen atom, a chlorine atom, a bromine atom, or an iodine atom, and each independently an alkoxy group having 1 to 10 carbon atoms or a hetero atom may contain an acyloxy group having 1 to 10 carbon atoms, a chlorine atom, a bromine atom, or an iodine atom, h is an integer of 1 to 4, i is each independently an integer of 1 to 3, and j is an integer of 2 to 10, k an integer of 1 to 4, l an integer of 1 to 3, m an integer of 1 to 3, and n an integer of 2 to 10, provided that X ² and X The alkoxy group and/or acyloxy group of ³ may be combined with other alkoxy group and/or acyloxy group of X ² and X ³ respectively to form a cyclic structure.
)

(In formulas (bc-1) to (bc-6), R ⁷ is each independently a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom, and R ⁸ contains a heteroatom. Each R ⁹ is independently a hydroxyl group, an alkoxy group with 1 to 20 carbon atoms which may contain a heteroatom, and a It represents a good hydrocarbon group with 1 to 20 carbon atoms, or a hydrogen atom.) 2. The coated inorganic fine particles according to claim 1, wherein the content of said volatile organic compound is 1 ppm or more and less than 50 ppm. 3. The coated inorganic fine particles according to claim 1, which have a refractive index of 1.5 or more. The coated inorganic fine particles according to any one of claims 1 to 3, wherein the inorganic fine particles are at least one selected from the group consisting of metal oxides having a refractive index of 1.5 or more. The coated inorganic fine particles according to any one of claims 1 to 4, wherein the inorganic fine particles are at least one selected from the group consisting of zirconium dioxide (ZrO ₂ ) and titanium dioxide (TiO ₂ ). The coating layer is a layer formed by reacting at least one selected from the group consisting of the compound represented by the formula (A-1) and the compound represented by the formula (A-2). The coated inorganic fine particles according to any one of claims 1 to 5. Compounds represented by any of the formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2) The coated inorganic fine particles according to any one of claims 1 to 6, wherein 3 parts by weight or more and 100 parts by weight or less are added to 100 parts by weight of the inorganic fine particles to react. The coated inorganic fine particles according to any one of claims 1 to 7, wherein the content of the coating layer is 1% by weight or more and 45% by weight or less. (1) a preparatory step of preparing an aqueous solution in which metal hydroxides and/or condensates of metal hydroxides are dissolved and/or dispersed; (3) an isolation step of isolating the inorganic fine particles produced in the hydrothermal reaction step; (4) The inorganic fine particles isolated in the isolation step and the following formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and ( Manufacture of coated inorganic fine particles, comprising a coating step of reacting at least one of the compounds represented by any of D-2) in an aqueous solvent, and having a volatile organic compound content of 89 ppm or less. Method.

(In formulas (A-1), (A-2), (B-1), (B-2), (C), (D-1), and (D-2), R ¹ is is a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, R ² is a j-valent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, or the number of silicon atoms 1 to 20 j-valent (poly)siloxy groups, R ³ and R ⁴ each independently have a structure represented by any one of the following formulas (bc-1) to (bc-6), R ⁵ R 6 is a hydrocarbon group having 4 to 30 carbon atoms which may contain a heteroatom, R ⁶ is an n-valent hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, and X ¹ is each X ² and X ³ are each independently an alkoxy group having 1 to 10 carbon atoms, a hydrogen atom, a chlorine atom, a bromine atom, or an iodine atom, and each independently an alkoxy group having 1 to 10 carbon atoms or a hetero atom may contain an acyloxy group having 1 to 10 carbon atoms, a chlorine atom, a bromine atom, or an iodine atom, h is an integer of 1 to 4, i is each independently an integer of 1 to 3, and j is an integer of 2 to 10, k an integer of 1 to 4, l an integer of 1 to 3, m an integer of 1 to 3, and n an integer of 2 to 10, provided that X ² and X The alkoxy group and/or acyloxy group of ³ may combine with other alkoxy group and/or acyloxy group of X2 and ^{X3 respectively} to form a cyclic structure.)

(In formulas (bc-1) to (bc-6), R ⁷ is each independently a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom, and R ⁸ contains a heteroatom. Each R ⁹ is independently a hydroxyl group, an alkoxy group with 1 to 20 carbon atoms which may contain a heteroatom, and a It represents a good hydrocarbon group with 1 to 20 carbon atoms, or a hydrogen atom.) A nanocomposite material obtained by dispersing the coated inorganic fine particles according to any one of claims 1 to 8 in a transparent organic compound. 11. The method according to claim 10, wherein the organic compound is a polymerizable monomer and/or oligomer, and the polymer obtained by polymerizing the monomer and/or oligomer has a spectral transmittance of 65% or more for light having a wavelength of 400 nm. A nanocomposite material as described. The organic compound is at least one selected from the group consisting of thermoplastic resins, thermosetting resins, ultraviolet curable resins, and electron beam curable resins, and has a spectral transmittance of 65% or more for light with a wavelength of 400 nm. The nanocomposite material according to claim 10, wherein The nanocomposite material according to any one of claims 10 to 12, wherein the content of said coated inorganic fine particles is 10% by weight or more and 85% by weight or less.

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