JP2002362923A - Method for producing metallic oxide particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing fine metallic oxide particles which consist not only of single metallic oxide, but also of solid solution oxide or compound oxide, and further has excellent dispersibility. SOLUTION: In the method for producing metallic oxide particles, a mixture containing metallic alkoxide and a carboxyl group-containing compound is heated, and they are reacted. The production method is characterized in that (1) the mixture does not substantially contain moisture and (2) the molar ratio of the carboxyl group-containing compound to the metallic alkoxide in the mixture is >0.8n (wherein, n is the valence of metallic atoms in the metallic alkoxide).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing fine metal oxide particles having excellent dispersibility.

[0002]

2. Description of the Related Art Metal oxide particles are used in vulcanization accelerators for rubber, various paints, printing inks, paints, glass, catalysts, pharmaceuticals, pigments, ferrites, and other raw materials.
Particles having a particle diameter of 0.1 μm or less and having high dispersibility are required.

[0003] Metal oxide particles can be obtained, for example, by subjecting a metal alkoxide to liquid phase hydrolysis in an alcohol in the presence of water and, if necessary, a basic catalyst such as ammonia. However, the particles obtained by this production method are generally spherical particles in the submicron to micron region that are secondary aggregated, and it is difficult to obtain fine particles of 100 nm or less. In addition, depending on the type of metal contained in the metal alkoxide, there is a remarkable difference in the hydrolysis rate of the metal alkoxide, and it is also difficult to directly obtain solid solution oxide particles or composite oxide particles.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide not only a single metal oxide but also a solid solution oxide or a composite oxide, and a fine metal oxide having excellent dispersibility. To provide a method for producing physical particles.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and by reacting a carboxyl group-containing compound with a metal alkoxide instead of the conventional alkaline hydrolysis method, a single metal is obtained. It has been found that metal oxide-based particles composed of not only oxides but also solid solution oxides and composite oxides are obtained. Furthermore, the present inventor has studied diligently to enhance the dispersibility of the obtained metal oxide-based particles and to reduce the particle size, and the amount of water contained in the reaction system, or
By focusing on the content of the carboxyl group-containing compound in the mixture and setting the reaction conditions, it has been found that excellent dispersibility and fine metal oxide-based particles can be obtained, and the present invention has been completed.

That is, a method for producing metal oxide particles according to the present invention is a method for producing metal oxide particles, in which a mixture containing a metal alkoxide and a carboxyl group-containing compound is reacted by heating. Is substantially free of moisture.

[0007] The method for producing metal oxide particles according to the present invention is a method for producing metal oxide particles in which a mixture containing a metal alkoxide and a carboxyl group-containing compound is heated and reacted. Wherein the molar ratio of the carboxyl group-containing compound to the metal alkoxide is more than 0.8n (where n is the valence of a metal atom in the metal alkoxide).

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing metal oxide particles according to the present invention is a method in which a mixture containing a metal alkoxide (compound containing a metal alkoxy group) and a compound containing a carboxyl group is heated and reacted.

As the metal alkoxide used in the above production method, a compound represented by the following general formula (1) is preferable.

M (OR^a)_nmR^b _m (1) (where M is a metal atom; R^aIs a hydrogen atom, is substituted
Alkyl group, cycloalkyl group, acyl
Group, aralkyl group, aryl group
1 type; R^bIs a hydrogen atom, an optionally substituted alkyl
Group, cycloalkyl group, acyl group, aralkyl group,
A reel group, an unsaturated aliphatic residue, and OR ^aNon-base
At least one selected from organic groups containing a functional group;
Valence of metal atom M; m is an integer in the range of 0 to n-1
You. ) In the general formula (1), R^aIncludes a hydrogen atom and / or
Is an optionally substituted group such as an alkoxyalkyl group.
Alkyl groups are preferred. Also, R^bAs being replaced
An alkyl group, a cycloalkyl group, an acyl group,
Aralkyl groups, aryl groups, unsaturated aliphatic residues, and
And OR of β-diketone compounds, etc.^aFunctional groups other than
At least one selected from organic groups
New

In the general formula (1), M is a symbol in the periodic table.
Ia, IIa, IIIa, IVa, Va, VIa, VIIa, V
Examples include all metal atoms contained in Group III, Group Ib, Group IIb, Group IIIb, and Group IVb, and may be lanthanoid-based or actinoid-based metal atoms. Further, as M other than the above, for example, P, Si, G
Examples thereof include group Vb metal atoms such as e, Sn, and Pb, group VIb metal atoms such as Se, Te, and Po, and group VIIb metal atoms such as At.

In the general formula (1), examples of the metal alkoxide with m = 1, 2 or 3 include various organosilicon compounds (m = 1, 2 or 3), titanate coupling agents (m = 1) , 2 or 3), an aluminate coupling agent (m = 1 or 2), and the like.

As the organosilicon compound, for example, vinyltrimethoxysilane, vinyltriethoxysilane,
Vinyl silane coupling agents such as vinyl tris (β-methoxyethoxy) silane and vinyl triacetoxy silane; N- (2-aminoethyl) -3-aminopropylmethyldimethoxy silane, 3-N-phenyl-γ-aminopropyl tri Methoxysilane, N, N'-bis [3-
(Trimethoxysilyl) propyl] amino-based silane coupling agents such as ethylenediamine; epoxy-based silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and β- (3,4-ethoxycyclohexyl) ethyltrimethoxysilane; Chlorosilane coupling agents such as 3-chloropropyltrimethoxysilane; methacryloxysilane coupling agents such as 3-methacryloxypropyltrimethoxysilane; mercaptosilane coupling agents such as 3-mercaptopropyltrimethoxysilane; N -(1,3-dimethylbutylidene) -3-
Ketimine silane coupling agents such as (triethoxysilyl) -1-propanamine; cationic silane coupling agents such as N- [2- (vinylbenzylamino) ethyl] -3-aminopropyltrimethoxysilane hydrochloride Alkyl silane coupling agents such as methyltrimethoxysilane, trimethylmethoxysilane, decyltriethoxysilane, and hydroxyethyltrimethoxysilane; and γ-ureidopropyltriethoxysilane.

Examples of titanate-based coupling agents include isopropyl triisostearoyl titanate, isopropyl trioctaloyl titanate, tetraoctyl bis (ditridecyl phosphite) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetraisopropyl tris ( Dioctyl pyrophosphate) titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, bis (dioctylpyrophosphate) ethylene titanate, isopropyl tri (dioctyl phosphate) titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, tetra (2, 2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, isopro Distearate isostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, and it can include isopropyl tricumylphenyl titanate.

As the aluminate coupling agent,
For example, diisopropoxyaluminum ethyl acetoacetate, diisopropoxyaluminum alkyl acetoacetate, diisopropoxyaluminum monomethacrylate, isopropoxyaluminum alkyl acetoacetate mono (dioctyl phosphate), cyclic aluminum oxide isopropylate, and the like can be given. .

The metal alkoxide used in the present invention may be other than those described above, and may be, for example, a heterometal alkoxide (including a compound containing a heterometallic oxoalkoxy group). Note that a heterometal alkoxide refers to a metal alkoxide having two or more different metal atoms and linked via an alkoxy group or an oxygen atom or by a metal-metal bond or the like. When a heterometal alkoxide is used, metal oxide-based particles composed of a composite oxide can be obtained.

Next, the carboxyl group-containing compound used in the above production method is a compound having at least one carboxyl group in the molecule, for example, formic acid, acetic acid,
Saturated fatty acids (saturated monocarboxylic acids) such as propionic acid, isobutyric acid, caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, acrylic acid,
Unsaturated fatty acids (unsaturated monocarboxylic acids) such as methacrylic acid, crotonic acid, oleic acid, linolenic acid, oxalic acid,
Malonic acid, succinic acid, adipic acid, suberic acid, β, β
-Chain polycarboxylic acids such as unsaturated polycarboxylic acids such as dimethylglutaric acid, unsaturated polycarboxylic acids such as maleic acid and fumaric acid, cyclic saturated carboxylic acids such as cyclohexanecarboxylic acid, benzoic acid, phenylacetic acid, toluyl Aromatic monocarboxylic acids such as acids, aromatic carboxylic acids such as unsaturated polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid and trimellitic acid, acetic anhydride, maleic anhydride, and pyromellitic acid Carboxylic anhydrides such as anhydrides, trifluoroacetic acid, o-chlorobenzoic acid, o-nitrobenzoic acid, anthranilic acid, p-aminobenzoic acid, anisic acid (p-methoxybenzoic acid), toluic acid, lactic acid, salicylic acid (O-hydroxybenzoic acid) and other hydroxyl groups other than carboxyl groups, amino groups, nitro groups, alkoxy groups Group, a sulfonic acid group, a cyano group, a compound having a functional group such as a halogen atom or an atomic group, an acrylic acid homopolymer, an acrylic acid-methyl methacrylate copolymer, and the like. And a polymer having the same. Among these carboxyl group-containing compounds, in order to obtain particles having excellent dispersibility, a saturated carboxylic acid is preferred, and acetic acid is most preferred. When the carboxyl group-containing compound is a liquid, it can be used as a reaction solvent described later.

In the present invention, a mixture containing the above-mentioned metal alkoxide and the above-mentioned carboxyl group-containing compound is heated and reacted, but this mixture may further contain a reaction solvent and the like.

The amount of the reaction solvent is not particularly limited, but the concentration of the metal alkoxide is preferably 1 to 50% by weight based on the total amount of the metal alkoxide, the carboxyl group-containing compound and the reaction solvent. Next, the used amount of the reaction solvent is set. Thereby, highly dispersible particles can be obtained economically.

As a reaction solvent, a solvent other than water, that is, a non-aqueous solvent is preferable. Non-aqueous solvents include, for example, hydrocarbons; halogenated hydrocarbons; alcohols, phenols, polyhydric alcohols and derivatives thereof having a hydroxyl group; ethers and acetals; ketones and aldehydes; esters; Derivative compounds in which active hydrogen is substituted with an alkyl group or an acetoxy group; silicone oils, mineral oils and the like.

Examples of the hydrocarbon include amylbenzene, isopropylbenzene, ethylbenzene, octane, gasoline, xylenes, diethylbenzene, cyclohexane, cyclohexylbenzene, cyclohexene, cyclopentane, dimethylnaphthalene, cymenes,
Show brain oil, styrene, petroleum ether, petroleum benzine,
Solvent naphtha, decalin, decane, tetralin, turpentine, kerosene, dodecane, dodecylbenzene, toluene, naphthalene, nonane, pine oil, pinene, biphenyl, butane, propane, hexane, heptane, benzene, pentane, mesitylene, methylcyclohexane,
Examples include methylcyclopentane, p-menthane, ligroin, liquid paraffin, and the like.

Examples of the above-mentioned halogenated hydrocarbon include allyl chloride, 2-ethylhexyl chloride, amyl chloride, isopropyl chloride, ethyl chloride, naphthalene chloride, butyl chloride, hexyl chloride, methyl chloride, methylene chloride, o -Chlorotoluene, p-chlorotoluene,
Chlorobenzene, chloroform, carbon tetrachloride, 1,1-
Dichloroethane, 1,2-dichloroethane, 1,1-dichloroethylene, 1,2-dichloroethylene, 2,3-
Dichlorotoluene, 2,4-dichlorotoluene, 2,5
-Dichlorotoluene, 2,6-dichlorotoluene, 3,
4-dichlorotoluene, 3,5-dichlorotoluene, dichlorobutanes, dichloropropane, m-dichlorobenzene, o-dichlorobenzene, p-dichlorobenzene,
Dibromoethane, dibromobutane, dibromopropane,
Dibromobenzene, dibromopentane, allyl bromide, isopropyl bromide, ethyl bromide, octyl bromide, butyl bromide, propyl bromide, methyl bromide, lauryl bromide, 1,
1,1,2-tetrachloroethane, 1,1,2,2-tetrachloroethane, tetrachloroethylene, tetrabromoethane, tetramethylenechlorobromide, 1,1,1
-Trichloroethane, 1,1,2-trichloroethane,
Trichloroethylene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, bromochloroethane, 1-bromo-
Examples thereof include 3-chloropropane, bromonaphthalene, hexachloroethane, pentamethylenechlorobromide and the like.

As the alcohol, for example, n-
Amyl alcohol, s-amyl alcohol, t-amyl alcohol, allyl alcohol, isoamyl alcohol, isobutyl alcohol, isopropyl alcohol,
Undecanol, ethanol, 2-ethylbutanol,
2-ethylhexanol, 2-octanol, n-octanol, glycidol, cyclohexanol, 3,5
-Dimethyl-1-hexyn-3-ol, n-decanol, tetrahydrofurfuryl alcohol, α-terpineol, neopentyl alcohol, nonanol, fusel oil, n-butanol, s-butanol, t-butanol, furfuryl alcohol, propargyl alcohol,
1-propanol, n-hexanol, 2-heptanol, 3-heptanol, n-heptanol, benzyl alcohol, 3-pentanol, methanol, methylcyclohexanol, 2-methyl-1-butanol, 2-methyl-1-butanol, 3-methyl-2-butanol,
3-methyl-1-butyn-3-ol, 4-methyl-2
-Pentanol, 3-methyl-1-pentyn-3-ol and the like.

Examples of the phenol include ethylphenol, octylphenol, catechol, xylenol, guaiacol, p-cumylphenol, cresol, m-cresol, o-cresol, p-cresol, dodecylphenol, naphthol, nonylphenol, phenol, Benzyl phenol, p-methoxyethyl phenol and the like can be mentioned.

Examples of the above-mentioned polyhydric alcohols and derivatives thereof having a hydroxyl group include ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monoethyl ether, ethylene glycol monophenyl ether, and ethylene glycol monobutyl ether. , Ethylene glycol monohexyl ether, ethylene glycol monomethyl ether, ethylene glycol monomethoxymethyl ether, ethylene chlorohydrin, 1,3-octylene glycol, glycerin, glycerin glycidyl ether, glycerin 1,3-diacetate, glycerin dialkyl ether, glycerin Fatty acid ester, glycerin monoacetate, 2-chloro-1,3-propanedi Lumpur, 3-chloro-1,2-propanediol, diethylene glycol, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, cyclohexanediol, dipropylene glycol, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether,
Dipropylene glycol monopropyl ether, dipropylene glycol monomethyl ether, tetraethylene glycol, triethylene glycol, triethylene glycol monoethyl ether, triethylene glycol monomethyl ether, tripropylene glycol, tripropylene glycol monomethyl ether, trimethylene glycol, trimethylol Ethane, trimethylolpropane, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,4-butenediol, propylene glycol, propylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol Monomethyl ether, propylene chlorohydrin, hexylene glycol, pentaerythritol 1,5-pentanediol, polyethylene glycol, fatty acid monoesters of polyethylene glycol, a polyoxyethylene derivative having a hydroxyl group at least one terminal, polyoxypropylene derivatives having a hydroxyl group at at least one end, and polypropylene glycol.

As the above ether and acetal,
For example, anisole, ethyl isoamyl ether, ethyl t-butyl ether, ethyl benzyl ether, epichlorohydrin, epoxybutane, crown ethers, cresyl methyl ether, propylene oxide, diisoamyl ether, diisopropyl ether, diethyl acetate, diethyl ether , Dioxane, diglycidyl ether, 1,8-cineole, diphenyl ether, dibutyl ether, dipropyl ether, dibenzyl ether, dimethyl ether, tetrahydropyran,
Tetrahydropifuran, trioxane, bis (2-chloroethyl) ether, vinylethylether, vinylmethylether, phenetole, butylphenylether, furan, furfural, methylal, methyl-t-
Examples thereof include butyl ether, methyl furan, monochlorodiethyl ether and the like.

Examples of the above ketones and aldehydes include acrolein, acetylacetone, acetaldehyde, acetophenone, acetone, isophorone, ethyl-n-butylketone, diacetone alcohol, diisobutylketone, diisopropylketone, diethylketone, cyclohexanone, di-n-propyl Ketone, holon, mesityl oxide, methyl-n-amyl ketone, methyl isobutyl ketone, methyl ethyl ketone, methyl cyclohexanone, methyl-n-butyl ketone, methyl-
Examples thereof include n-propyl ketone, methyl-n-hexyl ketone, and methyl-n-heptyl ketone.

Examples of the ester include diethyl adipate, dioctyl adipate, triethyl acetylcitrate, tributyl acetylcitrate, allyl acetoacetate, ethyl acetoacetate, methyl acetoacetate, methyl abietate, isoamyl benzoate, and benzoic acid. Ethyl, butyl benzoate, propyl benzoate, benzyl benzoate, methyl benzoate, isoamyl isovalerate, ethyl isovalerate, isoamyl formate, isobutyl formate, ethyl formate, butyl formate, propyl formate, hexyl formate, benzyl formate, formic acid Methyl, tributyl citrate, ethyl cinnamate, methyl cinnamate, amyl acetate, isoamyl acetate, isobutyl acetate, isopropyl acetate, ethyl acetate,
2-ethylhexyl acetate, cyclohexyl acetate, acetate n
-Butyl, s-butyl acetate, propyl acetate, benzyl acetate, methyl acetate, methyl cyclohexyl acetate, isoamyl salicylate, benzyl salicylate, methyl salicylate, diamyl oxalate, diemyl oxalate, dibutyl oxalate, diethyl tartrate, dibutyl tartrate, stearic acid Amyl, ethyl stearate, butyl stearate,
Dioctyl sebacate, dibutyl sebacate, diethyl carbonate, diphenyl carbonate, dimethyl carbonate, amyl lactate, ethyl lactate, butyl lactate, methyl lactate, diethyl phthalate, dioctyl phthalate, dibutyl phthalate, dimethyl phthalate, γ-butyrolactone, propion Isoamyl acid, ethyl propionate, butyl propionate, benzyl propionate, methyl propionate, borates, dioctyl maleate, diisopropyl maleate, diethyl malonate, dimethyl malonate, isoamyl butyrate, isopropyl butylate, ethyl butyrate, butyric acid Examples thereof include butyl, methyl butyrate, and phosphates.

The derivative compounds in which the active hydrogens of all the hydroxyl groups of the above polyhydric alcohols are substituted with an alkyl group or an acetoxy group include, for example, ethylene carbonate,
Ethylene glycol diacetate, ethylene glycol diethyl ether, ethylene glycol diglycidyl ether, ethylene glycol dibutyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol ethyl methyl ether, diethylene glycol diacetate , Diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol dibenzoate, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, triethylene glycol di-2-ethyl butyrate, triethylene glycol Lumpur dimethyl ether, polyethylene glycol fatty acid diesters, polyoxyethylene derivatives having no hydroxyl group at both ends, can be mentioned polyoxypropylene derivatives having no hydroxyl group at both terminals.

In the production method of the present invention, a mixture containing a metal alkoxide and a carboxyl group-containing compound, preferably further containing a non-aqueous solvent, is heated and reacted to obtain metal oxide particles. The heating temperature is usually 50 ° C. or higher, and is preferably 100 ° C. or higher in order to obtain particles having high crystallinity, and is in the range of 100 to 300 ° C. in order to obtain particles having more excellent dispersibility. Is preferred.

In the production method of the present invention, it is preferable that the mixture does not substantially contain water, and the metal oxide particles having a small particle size and a high dispersibility, for example, 10
Metal oxide particles having a fine particle diameter of 0 nm or less and having less secondary aggregation can be obtained. In addition, when the reaction solvent is contained in the mixture, it is preferable to use the above-mentioned non-aqueous solvent as the reaction solvent because it is easy to make the mixture substantially free of water.

In the production method of the present invention, the water content in the mixture is preferably a slight water content of less than 1 in a molar ratio to the metal atom in the metal alkoxide, more preferably. Is less than 0.2, even more preferably less than 0.1. If the above content, metal oxide particles having a small particle size and high dispersibility,
For example, metal oxide particles having a fine particle diameter of 100 nm or less and having less secondary aggregation can be obtained. When the reaction solvent is contained in the mixture,
It is preferable to use the above-mentioned non-aqueous solvent as the reaction solvent because it is easy to adjust the water content of the mixture to the above range. Further, the above-mentioned "the mixture does not substantially contain water" may preferably mean that the water contained in the mixture is within the above range of the content, which is preferable.

In the production method of the present invention, the mixing ratio of the metal alkoxide and the carboxyl group-containing compound in the mixture (carboxyl group-containing compound / metal alkoxide), that is, the metal alkoxide (metal alkoxyl group-containing compound) in the mixture About the molar ratio (carboxyl group-containing compound / metal alkoxide) obtained from the number of moles of the metal carboxyl group-containing compound to the number of moles, the lower limit is preferably set using the valence n of the metal atom M contained in the metal alkoxide. It is more than 0.8n, more preferably more than 2n, and preferably the upper limit is less than 10n.

The specific operation procedure of the production method of the present invention is not particularly limited, and includes, for example, 1) a method in which the above mixture is prepared at room temperature or 50 ° C. or lower, and the temperature is raised and heated; And a preheating method in which at least one of the carboxyl group-containing compound is heated and the other is mixed with the heated compound. As the preheating method, specifically, for example, a method in which a non-aqueous solvent and a carboxyl group-containing compound are heated and a metal alkoxide is added, and a method in which the non-aqueous solvent and the metal alkoxide are heated and Preferred examples include a method of adding a compound containing, a method of separately heating a metal alkoxide and a carboxyl group-containing compound and mixing them. Among the above methods 1) and 2), the preheating method is more preferable, the reaction temperature can be easily selected, and the control of the particle diameter and the composition can be easily performed. The preheating method is particularly effective for obtaining a solid solution having a high content of a composite oxide or a dopant metal having a desired composition. In this case, the lower the water content is, the more preferable it is.

The preheating temperature in the case of performing the above preheating method is such that the temperature is lowered by the subsequent mixing, and the minimum temperature is higher than 100 ° C., preferably higher than 150 ° C.
It is preferable to set in consideration of the heating capacity of the reactor and the like.

The heating reaction may be carried out under any of normal pressure, increased pressure and reduced pressure. When the boiling point of the non-aqueous solvent or the like is lower than the reaction temperature, the reaction may be carried out using a pressure-resistant reactor. Good. Usually, the reaction temperature and the gas phase pressure during the reaction are lower than the critical point of the solvent, but the reaction can be performed under supercritical conditions.

The metal oxide particles obtained by the production method of the present invention will be described in detail below.

It is preferable that the metal oxide-based particles show crystallinity based on the metal oxide by X-ray diffraction or electron beam diffraction. In general, when the primary particle diameter is 5 nm or more, X-ray diffraction is used. When the primary particle diameter is 5 nm or less, electron diffraction is used. Crystal structure and composition can be identified.

The metal oxide particles preferably have a primary particle diameter of 1 to 100 nm. The primary particle diameter can be confirmed, for example, by any of the following methods.

The crystallite size D obtained by Wilson analysis or electron beam diffraction in X-ray diffraction is used.
w.

The primary particle diameter De obtained by observing a projected image of a particle with a transmission electron microscope (TEM), preferably a high-resolution TEM, for example, a field emission TEM, and observing its crystal lattice image and size. De is 5 according to the particle projection image.
The particle diameter of zero particles is measured and calculated as a number average particle diameter based on the arithmetic average. In the measurement of De, the reactant or the fine particle dispersion was dispersed with alcohol at a fine particle concentration of 0.1%.
It is preferable to use a sample diluted to wt% as a sample.

Specific surface area diameter Ds calculated by the following equation.

Ds = 6 / (ρ × s) (where ρ: true specific gravity of metal oxide particles, s: BE
T. Specific surface area (m ²
/ G)) Both Dw and De are more preferably 1 nm ≦
Dw (or De) ≦ 50 nm, and preferably 1 nm ≦ Dw (or De) ≦ 30 nm for excellent electronic properties, and 1 nm ≦ Dw (or De) ≦ 5 nm is preferred. If Dw and De are too small, ultraviolet shielding properties, conductivity, etc., will be reduced. On the other hand, if it is too large, transparency to visible light decreases.

The above Ds is more preferably Ds <30n
m, more preferably Ds <15 nm, and when the quantum effect is required in terms of function, it is preferable that Ds <5 nm. If Ds is too small, the ultraviolet shielding property, the conductivity and the like are reduced. On the other hand, if it is too large, transparency to visible light decreases.

Further, since the metal oxide-based particles are used as a fine particle material having excellent optical, electronic physical properties and magnetic functions, they have a high transparency and substantially affect the hue of the composition containing the particles. In order not to give it, it is preferable to have excellent monodispersity. That is, it is important that the particle size distribution of the primary particle size is uniform, the degree of secondary agglomeration is low, and the like. More specifically, the variation coefficient of the primary particle size is 30% or less. And particularly preferably 10% or less.
Further, the secondary aggregation degree is preferably 10 or less, more preferably 5 or less, further preferably 2 or less, and particularly preferably 1. The secondary agglomeration refers to particles (secondary particles) in which primary particles are associated, and the degree of secondary agglomeration refers to the number of primary particles constituting the secondary particles. As another method of evaluating the secondary cohesiveness, there is a method of measuring the dispersed particle diameter (average dispersed particle diameter). The average dispersed particle diameter is preferably 200 nm or less, more preferably 70 nm or less. Yes, even more preferably 3
0 nm or less. The average dispersed particle size is measured by a device using a light scattering method. As a particularly preferred measuring device, a dynamic light scattering type particle size distribution measuring device LB-500 (manufactured by Horiba Ltd.) can be mentioned.

The particle shape of the metal oxide particles is not particularly limited. Specific examples of the shape include a flaky shape such as a spherical shape, an elliptical spherical shape, a cubic shape, a cuboid shape, a pyramid shape, a needle shape, a column shape, a rod shape, a tubular shape, a scale shape, a (hexagonal) plate shape, and the like.

It is preferable that the metal oxide-based particles are formed by bonding an alkoxy group or a carboxyl group, because of excellent dispersibility.

Metal oxide-based particles include semiconductor materials, conductive materials, light absorbing materials, luminescent materials, (optical) magnetic recording materials,
It can be used as ultrafine particles having various functions such as a nonlinear optical material and a ferroelectric material.

Hereinafter, classification examples of the electron valence of the metal atom M contained in the metal oxide-based particles obtained by the production method of the present invention will be described. Specific oxides and mixed valence oxides such as Fe ₃ O ₄ are also included. In addition, amorphous (hydr) oxides such as amorphous silica, oxide hydrates, and the like are also included. <Single oxide> (1) Oxide having three-dimensional lattice structure 1) M ₂ O-type oxide a. Oxides having an antifluorite-type crystal structure such as Li ₂ O, Na ₂ O, K ₂ O, and Rb ₂ O b. Oxides having a Cu ₂ O type crystal structure such as Cu ₂ O and Ag ₂ O 2) MO type oxides a. Alkaline earth metal oxides such as MgO, CaO, SrO and BaO; divalent first transition metal oxides such as FeO, CoO, NiO and MnO; oxides having a rock salt type crystal structure such as TiO and VO; b. Oxides having a wurtzite crystal structure, such as BeO and ZnO c. Oxide having a defective rock salt type crystal structure such as NbO d. Oxides having a PdO type crystal structure, such as PdO, PtO, CuO, AgO, etc. 3) M ₂ O ₃ type oxide a. Al ₂ O ₃ , Ti ₂ O ₃ , V ₂ O ₃ , Fe ₂ O ₃ , Cr
Oxides having a corundum crystal structure, such as ₂ O ₃ , Rh ₂ O ₃ , and Ga ₂ O ₃ b. Mn ₂ O ₃ , Sc ₂ O ₃ , Y ₂ O ₃ , In ₂ O ₃ , Tl ₂ O
An oxide having a c-M ₂ O ₃ type crystal structure such as ₃ c. oxides having a complex c-M ₂ O ₃ type crystal structure such as α-Bi ₂ O ₃ , β-Bi ₂ O ₃ , γ-Bi ₂ O ₃ d. Oxides e having B ₂ O ₃ type crystal structure such as a B ₂ O _3. Oxides having 4f and 5f oxides such lanthanide metal oxide 4) MO ₂ type oxide a. Oxides having a fluorite-type crystal structure, such as ZrO ₂ , HfO ₂ , CeO ₂ , ThO ₂ , and UO ₂ b. TiO ₂ , SnO ₂ , VO ₂ , CrO ₂ , MoO ₂ , W
Oxides having a rutile-type crystal structure, such as O ₂ , MnO ₂ , and GeO ₂ c. Oxides having a silica type crystal structure such as SiO ₂ and GeO ₂ 5) MO ₃ type oxides a. Oxides having ReO ₃ type crystal structure such as ReO ₃ and WO ₃ (2) Oxides having low dimensional lattice structure (2-1) Layered lattice structure oxide 1) M ₂ O type oxide a. Oxides having a cadmium antiiodide type crystal structure such as Ca ₂ O 2) MO type oxides a. Oxides having a PbO type crystal structure such as PbO and SnO 3) M ₂ O ₅ type oxides a. V ₂ O ₅ 4) MO ₃ type oxide a. MoO ₃ (2-2) Chain lattice structure oxide a. _{HgO, SeO 2, CrO 3,} Sb 2 O 3 (2-3) molecular lattice structure oxide a. RuO ₄ , OsO ₄ , Tc ₂ O ₇ , Sb ₄ O ₆ Next, as an oxide composed of two or more metal components,
Complex oxide, solid solution oxide, metal oxyacid (ion, salt)
Can be mentioned. The metal oxyacids (salts) are included in the composite oxide and exemplified below. <Composite oxide> 1) ABO ₂ type composite oxide MaMbO ₂ composed of monovalent metal Ma and trivalent metal Mb
Many of the type oxides are included in this, and for example, the following are exemplified.

A. An oxide having a crystal structure of a sphalerite-type superstructure such as LiBO ₂ b. Oxides having a wurtzite-type superstructure crystal structure such as LiGaO ₂ c. an oxide having a β-BeO type crystal structure such as γ-LiAlO ₂ d. LiFeO ₂ , LiInO ₂ , LiScO ₂ , LiE
uO ₂ , LiNiO ₂ , LiVO ₂ , NaFeO ₂ , NaI
oxides having a rock salt type superstructure crystal structure such as nO ₂ e. Ma = Cu, A such as CuCrO ₂ , CuFeO ₂
g, Mb = a semiconductive oxide composed of a combination of Al, Cr, Co, Fe, Ga, Rh, etc .; PdCoO ₂ , Pd
Ma = Pd such as CrO ₂ , PdRhO ₂ , PtCoO ₂ ,
HNaFO such as oxide made of Pt and having excellent metal conductivity
Oxide having ₂ type crystal structure 2) ABO ₃ type composite oxide a. Oxides having a c-M ₂ O ₃ type crystal structure such as ScTiO ₃ and ScVO ₃ b. FeVO ₃ , MnFeO ₃ , FeCrO ₃ , TiVO ₃
Or FeTiO ₃ , CoMnO ₃ , CoVO ₃ , NiTi
Ilmenite type structures such as O ₃ and CdTiO ₃ , LiNb
An oxide having a corundum type crystal structure such as a LiNbO ₃ type structure represented by O ₃ c. Oxides having LiSbO ₃ type crystal structure typified by LiSbO ₃ d. PbReO _3, other oxides having a defect pyrochlore type crystal structure such as BiYO _3, as ABO ₃ type oxide having a close-packed plane of the AO _3, BaNiO _3, perovskite _{oxides, BaMnO 3, SrTiO 3, Sr} 4 Re ₂ Sr
O ₁₂ and BaRuO ₃ can be exemplified. As the perovskite oxide, KTaO ₃ , NaNbO ₃ ,
Cubic perovskites such as BaMnO ₃ and SrTiO ₃ ;
BiAlO ₃ , PbSnO ₃ , BaTiO ₃ , PbTiO ₃
And other tetragonal perovskites; LaAlO ₃ , LiNi
Oxides having a LaAlO ₃ type structure, such as O ₃ , BiFeO ₃ , KNbO ₃ ; GdFeO ₃ , YFeO ₃ , NdGa
O _3, it may be mentioned oxides having a CaTiO ₃ type structure.

3) ABO ₄ type composite oxide The following composite oxides and oxyacid salts can be mentioned.

A. Oxides having a silica-like structure such as PBO ₄ and BeSO ₄ b. CrVO _4, ZnCrO ₄ oxides having CRVO ₄ type crystal structure such as c. oxides having α-MnMoO ₄ type crystal structure such as α-MnMoO ₄ d. Sealight such as CaWO ₄ and CaMoO ₄ (CaWO
₄ ) oxide having a type crystal structure e. Oxides having a defective celite type crystal structure, such as Bi ₂ (MoO ₄ ) ₃ and Eu ₂ (WO ₄ ) ₃ f. Oxides having a ferrugsonite type crystal structure such as MNbO ₄ and MTaO ₄ (M: trivalent) g. Zircons such as CaCrO ₄ and YVO ₄ (ZrSi
An oxide having an O ₄ ) type crystal structure h. Oxides having a rutile-type crystal structure such as CrVO ₄ and AlAsO ₄ i. Oxides having a Wolframite-type crystal structure, such as FeVO ₄ , FeWO ₄ , MnWO ₄ , and NiWO ₄ j. Oxides having a strained wolframite type crystal structure such as CuWO ₄ k. Oxides having CoMoO ₄ type crystal structure CoMoO ₄ etc. ₄₎ AB ₂ O 4 type composite oxide _{NiCr 2 O 4, CoCr 2 O} 4, MnCr 2 O 4, NiFe
_{In addition} to oxides having a spinel-type crystal structure such as ₂ O ₄ , CoFe ₂ O ₄ , MnFe ₂ O ₄ , and ZnFe ₂ O _4, oxides having a phenasite-type crystal structure such as Be ₂ SiO ₄ , and Ca
Fe ₂ O ₄ , CaTi ₂ O _{4 and the} like can be mentioned.

In addition to the above-mentioned oxides, silicates and aluminosilicates; polyacids such as Mo, W, V, Nb, Ta, etc., which are heteropolyacids incorporating heteroatoms; Mixed heteropolyacids in which a part of W, V and the like are substituted with different metals, salts thereof, and the like are also included in the oxides constituting the metal oxide-based particles obtained in the present invention. <Solid Solution Oxide> An interstitial or substitutional solid solution oxide obtained by dissolving a different metal in the above-described various single oxides or composite oxides can be used. For example, an In-based solid solution obtained by doping indium oxide with a tetravalent metal such as Sn or Ti, which is known as a white conductive oxide, or a tin oxide doped with a pentavalent metal such as Sb or P is used. Tin oxide-based solid solutions, zinc oxide solid solutions obtained by doping ZnO with a trivalent or tetravalent metal such as Al, In, Si, Mn, and zirconium oxide known as an ionic conductor include Y and Sc.
And a solid solution oxide such as a zirconium oxide-based solid solution doped with such a metal.

[0054]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the following, “parts by weight” may be simply referred to as “parts” for convenience.

Example 1 A pressure-resistant Hastelloy reactor (capacity: 100 liters) equipped with a stirrer, an addition port, a thermometer, a distillate gas outlet, and a nitrogen gas inlet, which can be heated from the outside, and addition. A reactor equipped with an addition tank directly connected to a mouth via a ball valve, a cooler directly connected to a distillate gas outlet, and a distillate trap was prepared. After the inside of the reactor was replaced with nitrogen, propylene glycol methyl ether acetate 4 was used as a non-aqueous solvent.
00 parts, acetic acid 48 as a carboxyl group-containing compound
And 68 parts of titanium n-tetrabutoxide as a metal alkoxide were sequentially charged, and the resulting solution (1) was heated while stirring. The water content of the solution (1) was below the measurement limit. After the internal temperature of the reactor reached 260 ° C., the temperature was maintained for 5 hours, and then cooled to obtain a reaction liquid containing fine particles.

The obtained reaction solution was a dispersion in which ultrafine particles of anatase type titanium oxide having a crystallite size of 7 nm were highly dispersed. The oxide concentration in the particles was 83% by weight based on the particles, and the yield based on the charged raw materials was 99%.
% Or more. As a result of analyzing the reaction solution, 85 parts of butyl acetate which was not a raw material and 7 parts of water were contained, but free acetic acid was not detected.

Comparative Example 1 Example 1 was repeated except that acetic acid was not used.
However, no fine particles were obtained.

Comparative Example 2 Except that, in Example 1, the solution (1) contained 1.7 parts of ion-exchanged water (about twice the molar ratio to Ti atoms in titanium n-tetrabutoxide). Was operated in the same manner as in Example 1. Although the obtained reaction solution contained anatase-type titanium oxide, it was an aggregate slurry and a large amount of deposits adhered to the wall surface of the reactor.

[0059]

According to the process for producing metal oxide particles of the present invention, fine metal oxide particles excellent in dispersibility can be obtained not only from a single metal oxide but also from a solid solution oxide or a composite oxide. Can be done.

Claims (3)

[Claims] 1. A method for producing metal oxide particles, in which a mixture containing a metal alkoxide and a carboxyl group-containing compound is heated and reacted, wherein the mixture does not substantially contain moisture. And a method for producing metal oxide-based particles. 2. A method for producing metal oxide particles, in which a mixture containing a metal alkoxide and a carboxyl group-containing compound is heated and reacted, wherein the molar ratio of the carboxyl group-containing compound to the metal alkoxide in the mixture is Is more than 0.8n (where n is the valence of a metal atom in the metal alkoxide). 3. The method for producing metal oxide-based particles according to claim 2, wherein the mixture contains less than 1 water in a molar ratio to a metal atom in the metal alkoxide.