JPH0586251B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for producing a powder of inorganic fine particles having excellent dispersibility in various solvents. More specifically, the present invention uses a specific device to produce a powder of inorganic particles that has very few aggregated particles and can be easily dispersed in various solvents, using a slurry of inorganic particles containing water in a solvent as a raw material. Relating to a method of manufacturing a body. <Prior art and its problems> Conventionally, methods for producing inorganic fine powder include mechanical pulverization of lumpy powder in a pulverizer in a solvent or non-solvent, and pulverization of a vaporizable metal compound in a vapor phase. A dry synthesis method in which fine particle powder is obtained by sputtering etc. from a metal plate, etc. that is a raw material for fine particles, hydrolyzing a hydrolyzable metal compound in a solution, or a raw metal compound in a solution. A known method is to produce a microparticle slurry by a so-called wet synthesis method in which microparticles are obtained in a solution by adding a precipitant or by ion exchange, and then separating and drying the particles from the slurry. Mechanical pulverization requires a large amount of energy for pulverization, and there are limits to particle size control.The particles obtained by this method have irregular shapes and a wide particle size distribution.
There is a problem in that the smaller the particle size, the more likely it is to aggregate. Particularly, when no solvent is used, particles agglomerate significantly. The dry synthesis method can produce very small primary particles, but the resulting powder is composed of secondary particles that are aggregates of primary particles, and has the problem of not being able to obtain dense particles and having a very large bulk specific gravity. . Although the wet synthesis method has the advantage that it is easy to obtain monodispersed fine particles in the slurry, it requires complicated steps of separating and drying the particles, and since water is present in the slurry,
There was a problem in that the particles tended to aggregate in each step, requiring a great deal of labor and expense to produce powder with excellent dispersibility. As a method for preventing the agglomeration of particles among the above problems, for example, after adding an organic solvent to a fine particle slurry and dehydrating it by heating it above the water distillation temperature, separating the particles from the organic solvent slurry of the particles. A drying method has been proposed. Although this method has the effect of preventing agglomeration of particles, it requires a large amount of organic solvent, and separate steps of separating the particles from the slurry and drying are required, and depending on the fine particles, aggregation may occur in each step. There was a problem. In addition, Japanese Patent Application Laid-open No. 138310/1983 describes a method for obtaining particle powder without agglomeration by supercritically treating a slurry of metal oxide fine particles obtained using metal alkoxide as a raw material with carbon dioxide gas. is proposed. However, this method has the disadvantage of being difficult to operate and requiring high equipment costs. On the other hand, as an economically advantageous method for producing powder of various pigment fine particles from a slurry of the fine particles,
It has been proposed to use a powdering device similar to that used in the present invention (Japanese Patent Publication No. 52-38272).
However, this method has a problem in that when the slurry contains water, the resulting powder contains many aggregated particles. As a method for solving the above problem, a method has been proposed in which, when water is contained in a slurry of fine pigment particles, a volatile organic solvent insoluble in water is allowed to coexist (Japanese Patent Publication No. 55-38588). However, when the present inventors conducted additional tests on the above-mentioned improvement method, they found that when the pigment particles are inorganic particles, even if a water-insoluble organic solvent coexists in the slurry, it is not very effective in preventing agglomeration. The result was that it was weak. In particular, in the case of fine particles of a metal oxide with a very active particle surface, such as those obtained by a wet synthesis method, this effect was not clearly observed. The treatment method for organicizing the surface of inorganic particles includes adding organic polymer compounds, alcohols, etc. to slurry of inorganic particles obtained by various manufacturing methods.
A known method is to add a surface treatment agent such as a coupling agent, perform surface treatment by heating or other means, and then evaporate the solvent to obtain a powder. However, in general, the surface of untreated inorganic fine particles is highly hydrophilic, and a large amount of water is adsorbed on the surface. Further, in the slurry, water or a strongly hydrophilic solvent is used as the dispersion medium due to the above-mentioned surface properties. Therefore, a large amount of water is present in the slurry in addition to the water adsorbed to the fine particles. These adsorbed water and coexisting water have become a factor that reduces the effectiveness of surface treatment of fine particles by a surface treatment agent that reacts with and binds to the surface of fine particles. Therefore,
Conventionally, inefficient methods have been adopted, such as using a large amount of surface treatment agent or performing surface treatment with a surface treatment agent after reducing adsorbed water and coexisting water. Furthermore, if you attempt to obtain surface-treated fine particles as a powder in the presence of the above-mentioned adsorbed water and coexisting water, the fine particles tend to aggregate under the influence of the water, making it difficult to obtain a powder with good dispersibility. There was a problem that I couldn't do it. Among the above problems, as a method for surface treatment without agglomerating particles, for example, Japanese Patent Publication No. 58-35736 discloses a method in which fine particles are dispersed in a solution of a surface coating treatment agent.
A method has been proposed in which the obtained dispersion solution is subjected to a surface coating treatment of fine particles using a powdering apparatus similar to that used in the present invention. However, in this method, the surface of the fine particles and the coating treatment agent are not bonded and the treatment agent is simply deposited or coated on the surface physically, so the surface-treated fine particles are redispersed in a desired solvent. When used as a treatment agent, depending on the solvent, the treatment agent may dissolve and peel off, and the effect of the treatment will not be apparent, resulting in a problem that the range of use is very narrowly limited. The basic difference between the method of the present invention and the above-mentioned known techniques is that the surface treatment in the former means that the surface of the fine particles is chemically bonded with a compound that is reactive therewith. Moreover, the above-mentioned document does not disclose anything about the possibility of reaction with a compound that can react and bond with the surface of inorganic fine particles under the condition that a large amount of water is present in the raw material slurry, and the manufacturing conditions for this reaction. Not yet. <Means for Solving the Problems> Therefore, an object of the present invention is to provide a method for producing a powder of inorganic fine particles that has better dispersibility in various solvents than a slurry of inorganic fine particles containing water in a solvent. , to the slurry (A) methanol and (B)
The solubility of water for organic compounds at 20℃ is
From the group consisting of organic compounds that are 1.0% by weight or more and can be azeotropically distilled with water, and the azeotropic composition of water in a binary azeotropic mixture of water and the organic compound is 4.0% by weight or more. A raw material slurry made of at least one selected material is coexisted with a tube that can be heated externally. One end of the tube is a raw material slurry supply port, and the other end is a steam-powder separation device maintained at reduced pressure. This is achieved by a method for producing powder of inorganic fine particles, which comprises powdering using a powdering device in which a powder collection chamber is connected to the separation device. The powder obtained by the method of the present invention has excellent dispersibility, so it can be used in various paints, inks, resins, etc.
When used as a filler in cosmetics, etc., the fine particles are easily and homogeneously dispersed or highly filled, so that the functions in those applications can be efficiently enhanced. Furthermore, when used as a raw material for various inorganic molded bodies, dense molded bodies with extremely low void ratios can be easily obtained, and thus have industrial value. The powder of inorganic fine particles produced according to the method of the present invention can be produced even if the slurry of the fine particles that is the raw material contains a large amount of water, ranging from several percent to several tens of percent. By coexisting the specified organic compound in the slurry, preferably in the specified amount, and by using the specified powdering equipment, it is possible to produce the slurry stably and with high productivity. be. The method of the present invention is particularly effective when producing a powder of metal oxide fine particles with almost no agglomerated particles. Furthermore, according to the method of the present invention, a compound capable of reacting with the surface of the inorganic fine particles is bound to the surface of the inorganic fine particles to make the fine particles organic, and the organic fine particles are stable under various usage conditions. Powder of inorganic fine particles with surface treatment is produced with high productivity. The inorganic fine particle powder produced according to the method of the present invention has a shape, an average particle diameter,
The particle size distribution is substantially the same as that of the fine particles in the slurry used as a raw material. The specific powdering device referred to in the present invention is:
A long pipe that is heated externally is provided, and one end (inlet) of the long pipe is a feed port for raw material slurry, and the other end (outlet) is connected to a powder separation device maintained at reduced pressure. ing. A powder collection chamber is attached to the separation device. The separating device is, for example, a bag filter. A specific method for pulverizing a raw material slurry prepared by coexisting with a specified organic compound using this pulverizing apparatus is as follows. A raw material slurry is continuously or intermittently supplied from the inlet of the long tube by a metering pump, and the slurry is converted into a mixture of fine particle powder and solvent vapor within the long tube. In the separator, only the powder in the mixture is separated, and the separated powder is collected in a powder collection chamber. On the other hand, the solvent vapor that has passed through the separation device is liquefied and separated by a condenser provided afterwards. A pressure reduction device, such as a vacuum pump, is provided after the condenser, thereby maintaining the entire powdering apparatus at reduced pressure. The inorganic fine particles in the present invention include silver, copper,
Fine metal particles such as iron and aluminum, fine particles of non-oxide inorganic compounds such as silicon carbide, silicon nitride, aluminum nitride, and boron nitride, silicon, aluminum,
Zirconium, magnesium, calcium, strontium, barium, yttrium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, iron, cobalt; nickel, copper, silver, zinc, cadmium, boron, gallium, indium, germanium, tin, Metal oxide or metal hydroxide fine particles containing antimony, bismuth, etc. as main components (hereinafter, in the present invention, metal hydroxides are also included in metal oxides,
(generally referred to as metal oxide fine particles); composite oxide fine particles consisting of two or more oxides of the above metals, such as barium titanate, lead titanate, and zeolite; organic groups in compounds of inorganic elements, such as silicon fine particles. so-called inorganic-organic composite systems, such as microparticles in which organic particles are bound together, microcapsule particles in which the outer surface of organic particles is coated with an inorganic compound, and microparticles in which an inorganic compound and an organic compound are simply mixed. Includes fine particles; etc. Among these fine particles, metal oxide fine particles and inorganic-organic composite fine particles are cited as those that exhibit the effects of the present invention significantly. A slurry of inorganic fine particles in a solvent containing at least water, which is a raw material for fine particle powder, can be prepared by wet-pulverizing coarse inorganic particles in a solvent containing water, by classifying inorganic fine particles in a solvent containing water,
A method in which powder obtained by a dry synthesis method is collected in a solvent containing water, and a wet synthesis method in which a slurry of inorganic fine particles is produced by hydrolyzing a metal compound in a solution containing water, adding a precipitant, ion exchange, etc. Obtained by other methods. Among these, it is preferable to use a wet synthesis method as a raw material for the fine particle powder, since the fine particles in the slurry are highly dispersed and it is easy to obtain a product with a uniform particle system. In particular, by a method of hydrolyzing and condensing an organometallic compound capable of hydrolysis and condensation in an organic solvent in the presence of water exceeding the hydrolysis equivalent to obtain a water-containing organic solvent slurry of metal oxide or metal hydroxide fine particles. Particularly preferred are those obtained. The method is described, for example, in the Journal of Colloid and Interface Science26.
Vol., pp. 62-69 (1968), and JP-A-62-148316. The organometallic compound has a hydrolyzable organic group,
Hydrolyzed and condensed into three dimensions (metal-oxygen)
As compounds capable of forming bonded chains, alkoxy metal compounds such as silicon, titanium, and zirconium are preferably used as they are industrially easily available and inexpensive. They have the general formula I R ¹ _n M (OR ² ) _o (I) (where M is a metal element, R ¹ is a hydrogen atom, an alkyl group with up to 10 carbon atoms which may have a substituent, an aryl group, At least one group selected from the group of unsaturated aliphatic residues, R ² represents an alkyl group.
m is 0 or a positive integer, n is an integer of 1 or more, and satisfies the valence of m+n=metal element M. Furthermore, m R ¹ may be different, and n
The same goes for ^R2 . ), but the metal element M is preferably silicon, titanium, zirconium, or aluminum. R ² is preferably a lower alkyl group having up to 8 carbon atoms. Alkoxy metal compounds where n is 3 or more can be used alone, but when n=1 or 2
The compound represented by can be used together with a raw material having three or more hydrolyzable organic groups. The above general formula R ¹ _n M
(OR ² ) Specific examples of the organometallic compound represented by _o include tetramethoxysilane, tetraethoxysilane, tetraisoproboxysilane, tetrabutoxysilane, trimethoxysilane, triethoxysilane, trimethylmethoxysilane, trimethoxyvinylsilane, triethoxyvinylsilane, 3-
Glycidoxypropyltrimethoxysilane, 3-
Chloropropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-(2-aminoethylaminopropyl)trimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethoxydimethylsilane, dimethoxymethylsilane, diethoxy Methylsilane, diethoxy-3-glycidoxypropylmethylsilane, 3-chloropropyldimethoxymethylsilane, dimethoxydiphenylsilane, dimethoxymethylphenylsilane, trimethylmethoxysilane, trimethylethoxysilane, dimethylethoxysilane, dimethoxydiethoxysilane, Titanium tetramethoxide, titanium tetraethoxide, titanium tetraisopropoxide, titanium tetrabutoxide, titanium diethoxydibutoxide, zirconium tetramethoxide, zirconium tetraethoxide, zirconium tetraisopropoxide, titanium tetra(2-ethylhexyl oxide) , aluminum triethoxide, aluminum triisopropoxide, aluminum tri-n-butoxide, aluminum tri-sec-butoxide, aluminum tri-tert-butoxide, and the like. Other preferred organometallic compounds include derivatives of these alkoxy metal compounds. An example is a compound in which some of the alkoxy groups (OR ² ) are substituted with a group that can form a chelate compound, such as a carboxyl group or a β-dicarbonyl group, or a partially hydrated alkoxy metal compound or alkoxy group-substituted compound. These include low condensates obtained by decomposition. Other organometallic compounds include, for example, titanium or zirconium acylate compounds such as zirconium acetate, zirconium oxalate, zirconium lactate, and titanium lactate; titanium acetylacetonate, zirconium acetylacetonate, titanium octyl glycolate, and titanium triethanolaminate. titanium or zirconium glycols, β-diketones, hydroxycarboxylic acids, etc.
Examples include chelate compounds such as ketoesters, ketoalcohols, aminoalcohols, and quinolines. In addition to the organometallic compounds mentioned above, sodium,
Composite oxidation with silicon, titanium, and/or zirconium by coexisting organometallic compounds or inorganic salts such as potassium, rubidium, cesium, magnesium, calcium, strontium, barium, boron, aluminum, gallium, and isodium and hydrolyzing them. It can also be a thing. In that case, the atomic ratio of silicon, titanium, and zirconium oxides is 70%.
It is preferable to set it as above. The above-mentioned organometallic compound is added and mixed into a solvent in which at least one of water and the organometallic compound is soluble and is hydrolyzed to produce a slurry of metal oxide fine particles. Examples of solvents include methanol, ethanol, n
-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, tert
-butanol, acetone, methyl ethyl ketone,
Tetrahydrofuran, dioxane, ethylene glycol, propylene glycol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, methyl lactate, ethyl lactate, n-hexane, cyclohexane, benzene, toluene,
Xylene and the like can be used alone or in mixtures. The amount of water supplied to the reaction can be calculated using the following equation: When the organometallic compound is represented by the above-mentioned general formula R ¹ _n M (OR ² ) _o , the hydrolysis reaction formula can be expressed as R ¹ _n M (OR ² ) _o +n/2H The amount should be greater than the equivalent of water when expressed as ₂ O→ R ¹ _n MO _o/2 + nR ² OH. By employing this method, a slurry is obtained which is dispersed in various organic solvents including water, and the fine particles therein become metal oxide spherical fine particles whose diameter is arbitrarily controlled in the range of 0.1 to 30 μm, and they are hydrolyzed. By suitably selecting these conditions, it becomes possible to have a narrow particle size distribution without agglomerated particles and with a coefficient of variation of the particle system in the range of 2 to 30%. The method of the present invention is most suitable as a method for obtaining a powder of metal oxide fine particles having no agglomerated particles and having a narrow particle size distribution from such a slurry of fine particles. In this case, as the fine particles, oxides of silicon, aluminum, zirconium, titanium, etc., composite oxides thereof, and composite oxides containing other metals such as alkali metals and alkaline earth metals can be manufactured. The slurry of inorganic fine particles obtained by the wet synthesis method contains water in the solvent, and as a result, when the fine particles are separated from the slurry and dried, the formation of aggregated particles is unavoidable. Particularly, in the case of fine particle powder having a narrow particle size distribution as described above, even the slightest amount of agglomerated particles is not allowed. A slurry of metal oxide fine particles obtained by hydrolyzing an organometallic compound has a concentration of fine particles of 1 to 15% by weight.
The slurry can be made to coexist with methanol (A) and/or an organic compound (B) and then used as a raw material slurry to be passed to the powdering device, but it is possible to make the slurry more susceptible to the formation of aggregated particles during powderization. In order to reliably prevent this, it has been found that it is preferable to heat the slurry after the reaction before passing it through the apparatus. The reason for this is to complete the hydrolysis and condensation reaction of the organometallic compound remaining in the slurry. This is because if the reaction is not completed and the organometallic compound or its low condensate is dissolved in the slurry, they will act as a binder and aggregate the particles during pulverization. The degree of completion of the hydrolysis reaction varies depending on the type of organometallic compound, amount of water, catalyst, etc., so an appropriate heating temperature cannot be specified, but it is preferably 30°C or higher, preferably 50°C. The temperature is above ℃. Most preferably, heating is carried out to the extent that a portion of the solvent in the slurry is evaporated in order to complete the reaction. It has also been found that if the fine particle concentration in the slurry is set to 10 to 40% by weight, powder free of agglomerated particles can be obtained even if the productivity of the powder is increased. A method to more reliably prevent the formation of agglomerated particles is as follows:
The goal is to limit the amount of water in the raw slurry to 3-30% by weight. Considering the amount of water inevitably contained in a slurry of fine particles obtained by a conventional wet synthesis method, it is economically disadvantageous to reduce the amount below the lower limit. If the amount exceeds the upper limit, the productivity of the powder will decrease, which is not preferable. When using the thus obtained slurry of metal oxide fine particles, the characteristics of the method shown in the present invention are best exhibited. The present inventors have discovered that when inorganic fine particle powder with no or very few aggregated particles is passed through a slurry containing water obtained by the above-mentioned manufacturing method through the above-mentioned apparatus, a specific organic compound They discovered that by coexisting with the slurry, it can be manufactured reliably and with high productivity. The organic compound is (A) methanol, and/or (B)
The solubility of water for organic compounds at 20℃ is
It is an organic compound which has an azeotropic composition of 1.0% by weight or more, and which is azeotropic with water and has an azeotropic composition of water of a binary azeotrope of water and an organic compound of 40% by weight or more. In addition to the above-mentioned properties, more preferable organic compounds (B) have a normal pressure boiling point of 120°C or lower, and even more preferable organic compounds (B) have a normal pressure boiling point of 100°C or lower. This is because the lower the boiling point of the organic compound (B), the higher the productivity of the powder. The present inventors believe that those with low boiling points are
We believe that this is related to the fact that the azeotropic temperature with water tends to be low. Therefore, a preferable organic compound (B) whose normal pressure boiling point is within the above range
is the azeotropic temperature in the binary azeotrope with water.
In other words, it means that the temperature is below 95℃. The type of organic compound that is azeotropic with water as referred to in the present invention, the azeotropic composition, azeotropic temperature, and normal pressure boiling point of water in a binary azeotrope mixture thereof with water are, for example, Advances In Chemistry Seyies
Volume 116, Azeotyopic Pata− (American
Chemical Society, 1973). If the water solubility of the organic compound (B) is less than 1.0% by weight, even if the organic compound has an azeotropic composition within the above range, there will be many aggregated particles in the powder. Furthermore, even if the solubility of water in the organic compound is 1.0% by weight or more, if it does not azeotrope with water or if the azeotropic composition of water is less than 4.0% by weight, it may aggregate in the powder. If the number of particles increases,
The productivity of trying to prevent the formation of aggregated particles is reduced. Data on the solubility of water for organic compounds can be found, for example, in Solubilities of Inorganic and Organic
Compounds (Pergamon Press, 1963) and
Listed in The Merck Index of Chemicals and Drugs. Specific examples of the organic compound (B) include ethanol,
n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol,
tert-butanol, sec-amyl alcohol, n
-bentanol, isoamyl alcohol, tert-
Amyl alcohol, n-hexanol, cyclohexanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 3-
Aliphatic lower alcohols with 2 or more carbon atoms such as methoxy-1-butanol and furfuryl alcohol; alicyclic alcohols; methyl ethyl ketone,
Ketones such as diethyl ketone and cyclohexanone; lower carboxylic acid esters such as ethyl formate, methyl acetate, ethyl acetate, ethylene glycol diacetate, diethyl maleate, 2-methoxyethyl acetate, and 2-ethoxyethyl acetate; tetrahydrofuran , cyclic ethers such as dioxane and tetrahydropyran, nitriles such as acetonitrile and propionitrile; amines such as cyclohexylamine, formic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, crotonic acid, methacrylic Examples include organic acids such as acids. Among these, specific examples of preferable organic compounds (B) include ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec.
-butanol, tert-butanol, sec-amyl alcohol, tert-amyl alcohol, 2-methoxyethanol, methyl ethyl ketone, diethyl ketone, methyl acetate, ethyl acetate, tetrahydrofuran, naoxane, tetrahydropyran, acetonitrile, propylonitrile, and the like. When the organic compound is methanol (A), the amount of the organic compound to be allowed to coexist is 1.0 times or more, preferably 2.0 times or more by weight the amount of water contained in the slurry. When the organic compound is organic compound (B), the amount of organic compound (B) calculated to form a binary azeotrope composition is 0.6 times or more by weight, preferably 0.8 times the amount of water contained in the slurry. The amount should be more than twice the weight.
It can also be made to coexist with methanol (A) and organic compound (B). Even if the amount is less than the above-mentioned amount, the effect of preventing agglomeration can be observed, but it is necessary to reduce the productivity of the powder.
There is no particular restriction on the upper limit of the amount that can coexist;
As long as the amount is at least within the above-mentioned range, the effect of preventing aggregation will not change even if the amount is large. In carrying out the method of the present invention, in addition to coexisting the above-mentioned methanol (A) and/or organic compound (B) in the raw material slurry, the solubility of water at 20°C is 1.0% by weight or more. Furthermore, an organic compound having a boiling point in the range of 105 to 300°C at normal pressure.
When (C) is allowed to coexist, the formation of agglomerated particles in the powder may be further prevented. In that case, the amount of the organic compound (C) to be allowed to coexist is preferably 0.1 times the amount of water contained in the slurry by weight. If the coexisting amount exceeds 1.0 times by weight, it is not preferable because the productivity of producing a powder free of agglomerated particles decreases. If the organic compound (C) is not azeotropic with water, it is necessary to reduce the coexisting amount as much as possible. Specific examples of the organic compound (C) include polyols such as ethylene glycol, propylene glycol, 1,3-propanediol, glycerin, 1,4-butanediol, 1,3-butanediol, diethylene glycol, and triethylene glycol; Examples include carboxylic acid esters such as methyl lactate and ethyl lactate; organic acids such as acetic acid and acrylic acid. In carrying out the method of the present invention, in addition to the above-mentioned organic compounds, a compound (D) having a group capable of reacting with the surface of the inorganic fine particles is coexisting in the raw material slurry. A powder of organicized inorganic fine particles in which the compound (D) is bonded to the surface of the powder and has very few aggregated particles can be produced with high productivity. As compound (D), an organic compound having at least one hydroxyl group in the molecule or a coupling agent is preferable. Examples of organic compounds having at least one hydroxyl group in the molecule include methanol, ethanol, n-propanol, isopropanol, n-
butanol, isobutanol, sec-butanol,
tert-butanol, amino alcohol, sec-amyl alcohol, n-pentanol, 2-methyl-1-butanol, isoamyl alcohol, tert
-amyl alcohol, n-hexanol, 2-decyl alcohol, lauryl alcohol, cyclohexanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 3-
Methoxy-1-butanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)ethanol, diacetone alcohol, furfuryl alcohol, benzyl alcohol, phenol, o-cresol, m-cresol, p-cresol , allyl alcohol, trans-2-buten-1-ol, propargyl alcohol, ethylene glycol, propylene glycol, 1,3-
Propanediol, 1,4-butanediol,
1,3-butanediol, cis-butanediol,
trans-butenediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, glycerol, monoethanolamine,
Diethanolamine, (±)-3-(dimethylamino)-1,2-propanediol, dimethylethanolamine, 1-dimethylamino-2-propanol, 3-dimethylamino-1-propanol, 2-cyanoethanol, 2,2 There may be a substituent such as '-thiodiethanol. These are aliphatic, aromatic, and alicyclic hydrocarbon alcohols. These organic compounds can be the same as the above-mentioned organic compounds (B) or (C) coexisting in the present invention when they are alcohols. Coupling agents include silane-based, titanate-based,
Aluminum-based coupling agents are preferred because they are easily available industrially. They are, for example, methyltrimethoxysilane, phenyltrimethoxysilane, benzyltrimethoxysilane, methyltriisopropoxysilane, 3-chloropropyltrimethoxysilane, dimethoxydimethylsilane, diethoxymethylphenylsilane, ethoxytrimethylsilane, 3-aminopropyltriethoxysilane, 3-(2-aminomethylaminopropyl)trimethoxysilane, (N,
Alkoxysilanes such as N-dimethyl-3-aminopropyl)trimethoxysilane, 3-glycidoxypropyltrimethoxysilane, allyltriethoxysilane, vinyltriethoxysilane, chlorosilanes such as trimethylchlorosilane and diethyldichlorosilane, acetoxy Silane couplings having one or more (substituted) alkyl groups, (substituted) phenyl groups, vinyl groups, etc. in the molecule, such as acetoxysilanes such as triethylsilane, diacetoxydiphenylsilane, and triacetoxyvinylsilane. Examples include, but are not limited to, titanate-based coupling agents such as isopropyl triisostearoyl titanate and bis(dioctylpyrophosphate) oxyacetate, and aluminum-based coupling agents such as acetalkoxyaluminum diisopropylate. . These compounds (D) may be used alone or in combination with two
It is used in combination of more than one species. The type and amount of compound (D) used vary depending on the type and concentration of fine particles in the slurry. Compound (D)
When the alcohol is used, the amount used should be 0.01 or more by weight relative to the fine particles, and in the case of a coupling agent, the weight ratio is preferably 0.001 to 0.1. If it is below the lower limit, the surface treatment effect will be small, and if it is above the upper limit, it will be effective but not economical. In the present invention, the surface treatment refers to the surface treatment of fine particles.
M ¹ −OH group (M ¹ is the metal element that makes up the fine particles)
and Compound (D) to carry out a reaction involving chemical bonding, such as esterification or condensation reaction. The slurry of fine particles obtained by the wet synthesis method contains water in the solvent, and as a result, compound (D) is present in the slurry.
Even if you add it and heat it as is, it will not be easily surface treated.
Moreover, the powder obtained from the slurry containing compound (D) contains many aggregated particles. The reason for this is that when the fine particles become powder, −M ¹ −
This is thought to be because a large amount of OH groups still exists. The present inventors added a slurry containing fine water particles to a slurry containing fine particles of water.
By using a raw material slurry in which the above-mentioned organic compound and compound (D) coexist, and by pulverizing the raw material slurry using a specified powdering device, it is possible to check whether there are any agglomerated particles. It has been found that an inorganic fine particle powder whose surface is treated with compound (D) can be easily produced in a very small amount. Furthermore, the present inventors found that the slurry of fine particles was obtained by hydrolyzing an organometallic compound in a solvent containing water, and the powder was obtained according to the method described above. When the powder is made of treated metal oxide fine particles, the powder can be fired at a temperature higher than the temperature at which the organic groups bonded to the surface of the fine particles decompose. It was also confirmed that the present invention is an industrially advantageous raw material for porous metal oxide fine particle powder that satisfies all of the physical properties shown below and has very few aggregated particles. That is,
The physical properties are that the fine particles are spherical, the diameter is in the range of 0.1 to 3.0 μm, the coefficient of variation of the particle system is in the range of 2 to 30%, and S × d × ρ>
30 (However, S is the specific surface area (m ² /g) of the fine particle powder measured by the BET method, d is the number average particle diameter (m) measured by electron microscopy, and ρ is the true density of the fine particle powder ( g/m ³ ). In this case, it is preferable that the alcohol has two or more carbon atoms. In general, for true spherical fine particles that have smooth, non-porous particle surfaces with no irregularities, S×d×ρ=
There are 6 relationships. The temperature at which an organic group decomposes varies depending on the type of organic group, but is at least 300°C, preferably 800°C.
The temperature is as follows. The operating conditions of the powdering apparatus in the present invention are not limited, but the temperature may be at least the dew point at the operating pressure of the solvent contained in the raw material slurry, the organic compound coexisting, and compound (D). The operating pressure is below atmospheric pressure, which enables stable operation at low cost, and preferably the pressure in the powder collection chamber is 20 to 500 Torr.
It is. (Examples) The present invention will be explained by examples, but the scope of the present invention is not limited by these.
In addition, in the reference examples and examples, the shape and average particle diameter of the fine particles, the coefficient of variation of the fine particles, the particle size distribution,
The specific surface area and density of the powder, the concentration of fine particles in the slurry, and the water content were measured as follows. ● Shape and average particle diameter of fine particles We observed the shape of fine particles using a transmission electron microscope image magnified 50,000 times, and then measured the individual particle diameter (Di) of more than 100 particles (number of measured particles = n). The average particle diameter (d) was calculated based on the following formula. Here, the particle diameter of each particle was the average value of the longest diameter and the shortest diameter of the particles. In addition, when the particles were aggregated, the aggregate of the aggregated particles was regarded as one particle.

[C] ● Coefficient of variation of particle size From Di and d measured by the method described above,
Calculated based on the following formula

[C] ●Particle size distribution The slurry obtained in the reference example and the slurry obtained by dispersing the powder obtained in the example or comparative example in various solvents were measured using a centrifugal sedimentation particle size distribution analyzer (SA-CP3 model manufactured by Shimadzu Corporation). ). ●Specific surface area of powder The powder obtained in the examples and comparative examples was
The samples were baked in an air atmosphere at a temperature range of 5 hours and then measured by the BET method. ●Density of powder Powder density was measured using an autopycnometer 1320 manufactured by Shimadzu Corporation on the same sample as used for measuring the specific surface area. ●Concentration of fine particles in alcohol Regarding the fine particle slurry obtained in the reference example,
After evaporating the solvent in the precisely weighed slurry,
Precisely weigh the residue after firing at 1000℃ as the amount of fine particles,
Calculated as weight %. ●Water content in slurry Regarding the slurry of fine particles obtained in the reference example,
Measured by Karl Fischer method. Production of Slurry of Inorganic Fine Particles Table 1 shows the water content in the slurry obtained in each reference example and the physical properties of the fine particles therein. Reference Example 1-(1) A mixture of 25 kg of silicon carbide coarse powder and 50 kg of water was wet-pulverized using an eccentric vibrating mill to obtain a slurry of silicon carbide fine particles. The obtained fine particles have an average particle size of
2.5 μm, the coefficient of variation of particle size is 47%,
Particle size distribution on the coarse particle side is 10 μm or more, 10% by weight,
It was 20 μm or more and 2% by weight. Reference example 1-(2) 25 kg of coarse mullite powder, 3 kg of water and ethyl acetate
A mixture of 97 kg was wet-pulverized using an eccentric vibrating mill to obtain a slurry of fine mullite particles. Reference Example 1-(3) A slurry of fine mullite particles was obtained in the same manner as in Reference Example 1-(2) except that acetone was used instead of ethyl acetate. Reference Example 1-(4) Add ammonia water to an aqueous solution (0.1 mol/) of yttrium chloride and zirconium chloride to perform hydrolysis, and produce fine particles of yttrium-zirconia composite hydrate (10 mol/yttrium in terms of oxide).
) was obtained. The suspension was filtered and thoroughly washed with pure water to form a cake. The cake was again dispersed in pure water to obtain a slurry of fine particles. Reference Example 1-(5) A solution consisting of 50 kg of partial condensate of tetramethoxysilane (average tetramer) and 160 kg of acetone was
%Ammonia water 45Kg, water 35Kg and acetone 160Kg
In addition to the solution consisting of silica, spherical fine particles (5.6% by weight), acetone (69.8% by weight), water (14.3% by weight), methanol (7.4% by weight), and ammonia (2.9% by weight) were mixed uniformly and left to stand. %) was obtained. Reference Example 1-(6) 6 kg of ammonia was dissolved in a mixed solution of 26 kg of water and 102 kg of methanol. The solution has an average particle size of
1 kg of monodispersed silica spherical fine particles of 5.0 μm were added and completely dispersed. 66 kg of tetramethoxysilane was gradually added to the dispersion to grow fine particles to obtain a slurry of fine silica particles. The composition of the slurry was spherical fine particles of silica (13.4% by weight), methanol (78.4% by weight), water (5.2% by weight), and ammonia (3.0% by weight). Reference Example 1-(7) While stirring a solution of 228 kg of water and 72 kg of ammonia mixed in 1640 isopropyl alcohol, 130 kg of triisopropoxyaluminum was gradually added to the solution to perform hydrolysis and condensation reactions to form spherical alumina. A slurry consisting of fine particles (1.9% by weight), water (12.2% by weight), ammonia (4.2% by weight), and isopropyl alcohol (81.7% by weight) was obtained. Reference Example 1-(8) While stirring the solution, 82 kg of tetra-n-butoxyzirconium was added to a solution consisting of 44 kg of water and 1880 n-propanol to perform a hydrolysis and condensation reaction, resulting in spherical fine particles of zirconia ( 3.5% by weight), water (1.4% by weight), n-propanol (86.5% by weight)
A slurry consisting of n-butanol (8.5% by weight) and n-butanol (8.5% by weight) was obtained. Reference Example 1-(9) While stirring the solution, 86 kg of tetraisopropoxy titanium was gradually added to a solution consisting of 36 kg of water and 1880 methanol to carry out a hydrolysis and condensation reaction. %),
A slurry consisting of water (1.6% by weight), methanol (92.5% by weight), and isopropanol (4.4% by weight) was obtained. Reference Example 1-(10) 600 kg of methyltrimethoxysilane was poured into a homogeneous solution consisting of 4000 kg of water and 50 kg of 28% aqueous ammonia to form two layers, the lower layer being an aqueous phase and the upper layer being methyltrimethoxysilane. Next, the mixture was gently stirred while maintaining the two-layered state, and hydrolysis and condensation reactions were carried out at the interface, and after 5 hours, the upper layer disappeared to obtain a single-phase slurry. The composition of the slurry is: polymethylsilsesquioxane (CH ₃ SiO _3/2 ) spherical fine particles (6.4% by weight), water (84.2% by weight), ammonia (0.3% by weight), methanol (9.1% by weight).
It was hot. Production of powder raw material slurry In Reference Example 2, the name of the organic compound coexisting in the raw material slurry, the weight ratio of the organic compound to water present in the slurry, the solubility of water to the organic compound at 20°C (i.e., the solubility of water at 20°C) , indicates the weight (grams) of water contained in 100 g of the organic compound phase in which water is saturated and dissolved, expressed in Sw), the normal pressure boiling point of the organic compound (expressed in Bp),
When an organic compound forms a binary azeotrope with water, the composition of water in the azeotrope (expressed in Cw) is calculated as the amount of water coexisting in the raw material slurry and the composition of the binary azeotrope. The weight ratio (expressed as k) of the amount of the organic compound coexisting with respect to the amount of the organic compound contained in the raw material slurry, the fine particle concentration (% by weight) in the raw material slurry, etc. are listed in Table 2. Reference Example 2-(1) 75 kg of the silicon carbide fine particle slurry obtained in Reference Example 1 was mixed with 40 kg of methanol to produce a uniform silicon carbide raw material slurry. Example 2-(2) A silicon carbide raw material slurry was produced in the same manner as in Reference Example 2-(1) except that the amount of methanol was changed to 90 kg. Reference Example 2-(3) A silicon carbide raw material slurry was obtained in the same manner as Reference Example 2-(1) except that the same amount of water was mixed instead of methanol in Reference Example 2-(1). Reference Example 2-(4) In Reference Example 2-(1), except that the same amount of ethylene glycol was mixed instead of methanol, the same procedure as Reference Example 2-(1) was carried out to obtain a silicon carbide raw material slurry. Ta. Reference Example 2-(5) The slurry of fine mullite particles obtained in Reference Example 1-(2) was used as a raw material slurry. Reference Example 2-(6) A raw material slurry was prepared by mixing 125 kg of the slurry of fine mullite particles obtained in Reference Example 1-(3) with 30 kg of toluene. Reference Example 2-(7) 60 kg of the slurry of yttria-zirconia composite hydrate fine particles obtained in Reference Example 1-(4) was mixed with 220 kg of methyl ethyl ketone to obtain a uniform raw material slurry. Reference Example 2-(8) A raw material slurry was produced in the same manner as in Reference Example 2-(7) except that the amount of methyl ethyl ketone was changed to 102 kg. Reference Example 2-(9) In Reference Example 2-(7), methyl ethyl ketone
2-methoxyethyl acetate instead of 220Kg
A raw material slurry was produced in the same manner as in Reference Example 2-(7) except that 25.8 kg was used. Reference example 2-(10) In reference example 2-(7), methyl ethyl ketone 220
A raw material slurry was produced in the same manner as in Reference Example 2-(7) except that 66.5 kg of n-propanol was used instead of 66.5 kg of n-propanol. Reference example 2-(11) In reference example 2-(7), methyl ethyl ketone 220
A raw material slurry was produced in the same manner as in Reference Example 2-(7) except that 50 kg of methanol was used instead of 50 kg. Reference Example 2-(12) A slurry obtained by carrying out the same procedure as Reference Example 2-(11) except that acetone was used instead of methanol was used as a raw material slurry. Reference Example 2-(13) 110 kg of the slurry obtained in Reference Example 2-(12) was mixed with 50 kg of propylene glycol to prepare a raw material slurry. Reference Example 2-(14) 50 kg of cyclohexanone was mixed with 110 kg of the slurry obtained in Example 2-(12) to obtain a raw material slurry. Reference Example 2-(15) The slurry of spherical fine silica particles obtained in Example 1-(5) was used as a raw material slurry. Reference Example 2-(16) The slurry of spherical fine silica particles obtained in Reference Example 1-(6) was used as a raw material slurry. Reference Example 2-(17) The slurry of spherical fine particles of silica obtained in Reference Example 1-(6) was charged into an evaporation pot equipped with a stirrer that could be heated from the outside, and heat-treated by heating the slurry at a temperature of 60°C or higher for 2 hours. During this time, the evaporating solvent was condensed and taken out of the system. In this way, spherical fine particles of silica (23.4% by weight), methanol (63.2% by weight), water (13.3% by weight), ammonia (0.1% by weight)
A raw material slurry consisting of Reference Example 2-(18) In Reference Example 2-(17), ethylene glycol was added to the slurry of spherical fine particles of silica obtained by heat treatment in an amount of 0.3 times the weight of the silica to obtain a raw material slurry. Reference Example 2-(19) The slurry of spherical fine particles of alumina obtained in Reference Example 1-(7) was charged into an evaporation pot equipped with an externally heated stirrer, and the slurry was heated for 2 hours at a temperature of 81°C.
A portion of the solvent was distilled off and heat treatment was performed.
In this way, a raw material slurry consisting of spherical fine particles of alumina (10.5% by weight), water (16.0% by weight), and isopropyl alcohol (73.5% by weight) was produced. Reference Example 2-(20) The slurry of zirconia spherical fine particles obtained in Reference Example 1-(8) was used as a raw material slurry. Reference Example 2-〓 The slurry of titania spherical fine particles obtained in Reference Example 1-(9) was placed in an evaporation pot that could be heated externally and was equipped with a stirrer, and heated to 50°C or higher for 1 hour to evaporate some of the solvent. A heat treatment was performed at the same time as distillation. In this way, a raw material slurry consisting of titania spherical fine particles (8.0% by weight), water (4.8% by weight), methanol (82.4% by weight), and isopropyl alcohol (4.8% by weight) was produced. Reference Example 2-(22) The slurry of spherical fine particles of polymethylsilsesquioxane obtained in Reference Example 1-(10) was heat-treated in the same manner as in Reference Example 2-(21) to obtain a concentrated slurry. . The composition of the slurry is: fine particles (26.5% by weight),
They were water (72.3% by weight) and methanol (1.2% by weight). For 100 kg of slurry, propionic acid
11.0Kg was added and mixed to form a raw material slurry. Reference Example 2-(23) 0.27 kg of phenyltrimethoxysilane is added to 55 kg of the slurry of fine particles of the yttria-zirconia composite hydrate mixed with methanol obtained in Reference Example 2-(11).
was added and thoroughly mixed to produce a raw material slurry. Reference Example 2-(24) In Reference Example 2-(17), 3-aminopropyltriethoxysilane was added 0.05 times the weight of the silica to the slurry of spherical fine particles of silica obtained by heat treatment to produce a raw material slurry. did. Production of Powders of Inorganic Fine Particles The dispersibility of the powders obtained in the following Examples and Comparative Examples in various solvents was evaluated as follows. That is, after adding 5 g of each powder sample to 100 ml each of methyl ethyl ketone (MEK), toluene, methyl methacrylate (MMA), and water as solvents, the powders were incubated under the same conditions for 20 minutes using an ultrasonic homogenizer. The particle size distribution of each slurry obtained in Reference Example 1 is almost the same as that of the slurry obtained in Reference Example 1, and there is no aggregation of particles due to pulverization. The evaluation was made by marking ◎, ○ if the particle size distribution slightly shifted toward the larger particle size and slight agglomeration, and × if the particle size distribution shifted significantly and showed a lot of aggregation. The particle size distribution in Table 4 indicates that the powder
This is the measured value when dispersed in MEK. The inorganic fine particles are metal oxide fine particles,
When Compound (D) coexists in the raw material slurry, it can be determined from its absorption spectrum using a Fourier infrared spectrophotometer that Compound (D) is bound to the surface of the fine particles of the obtained powder. confirmed. On the other hand, the bound compound (D) was quantified by the following method. In other words, about 10g of precisely weighed powder sample is heated to 0.05N−
Add to NaOH aqueous solution and allow to perform hydrolysis at room temperature for 10 hours. Since the hydrolyzed liberated Compound (D) was extracted into an aqueous solution, Compound (D) in the aqueous solution was quantified by gas chromatography. Furthermore, after contacting the powder in various solvents at room temperature for one week with stirring, it is confirmed that the physical properties of the powder from which the fine particles have been separated are unchanged from the original powder. It was proved that compound (D) was bound to the surface of the microparticles. Example 1 A long stainless steel pipe with an inner diameter of 8 mm and a length of 8 m is heated by passing pressurized steam through a jacket covered with it, and from one end of the long pipe (raw material slurry supply port) The raw material slurry of silicon carbide fine particles obtained in Reference Example 2-(1) was continuously fed using a metering pump. The other end of the long pipe is
It is held at a certain degree of vacuum and connected to a bag filter that separates the powder and the evaporated solvent, and the silicon carbide fine particle powder separated there is transferred to the powder collector at the same degree of vacuum. Collected in the room. The operating conditions for pulverization are shown in Table 3. Although the system was operated continuously for 5 hours in this manner, fine particles were found to have adhered and precipitated inside the long tube, which was the evaporation tube. By cleaning the long pipes, we were able to operate again under the same conditions. Table 4 shows the physical properties of the obtained powder. Comparative Example 1 A semi-cylindrical kneader with a capacity of 30 mm and equipped with a horizontal stirring device in which spiral stirring blades were attached to the stirring shaft was used as a powdering device. The kneader is equipped with a jacket and serves as a heat source to evaporate the solvent in the slurry through pressurized steam (200°C). Further, the inside of the kneader can be maintained at a constant degree of reduced pressure. After first charging the raw material slurry of silicon carbide fine particles obtained in Reference Example 2-(1) into the kneader, the system was maintained at 200 Torr and pressurized steam was passed through the jacket to evaporate the solvent. Next, the raw material slurry was supplied using a metering pump to maintain the liquid level of the slurry in the kneader. After operating in this way for 3 hours, the supply of the raw material slurry was stopped while the kneader continued to be heated. The temperature of the powder
When the temperature reached 150°C, heating and depressurization were stopped to obtain a powder of silicon carbide particles. Table 4 shows the physical properties of the powder. Example 2 Silicon cocarbide powder was produced in the same manner as in Example 1, except that the slurry obtained in Reference Example 2-(2) was used as the raw material slurry. Although the operation continued for 5 hours, no fine particles were deposited and attached to the long tube. The operating conditions and physical properties of the powder are shown in Tables 3 and 4. Comparative Examples 2 and 3 Silicon carbide powder was prepared in the same manner as in Example 1, except that the slurry obtained in Reference Example 2-(3) or Reference Example 2-(4) was used as the raw material slurry. Obtained. However, after 30 minutes in each case, it became impossible to supply the raw material slurry. When the system was stopped and the inside of the long tube was observed, a large amount of fine particles were deposited and adhered to the inlet. Furthermore, the obtained powder contained many aggregated particles. The operating conditions and physical properties of the powder are shown in Tables 3 and 4. Example 3 Mullite powder was produced in the same manner as in Example 1, except that the slurry obtained in Reference Example 2-(5) was used as the raw material slurry. Even after 5 hours of operation, no fine particles were observed to adhere or precipitate inside the long tube. The operating conditions and physical properties of the powder are shown in Tables 3 and 4. Comparative Example 4 Reference Example 2 was used as the raw material slurry in Example 1.
- Mullite powder was obtained in the same manner except that the slurry obtained in (6) was used. However, after one hour, it became impossible to supply the raw material slurry. When the system was stopped and the inside of the long tube was observed, a large amount of fine particles were deposited and fixed at the inlet. Furthermore, the obtained powder contained many aggregated particles. The operating conditions and physical properties of the powder are shown in Tables 3 and 4. Examples 4 to 9 The same procedure as in Example 1 was carried out except that each of the raw material slurries obtained in Reference Examples 2-(7) to (11) and 2-(14) was used as the raw material slurry. A powder of yttria-zirconia composite hydrate fine particles was produced. In all of these Examples, stable continuous operation was possible, and the resulting powders were well dispersed. However, Examples 5 and 6 using the raw material slurries obtained in Reference Examples 2-(8), 2-(9), and 2-(14)
and 9, it was necessary to lower the powder yield compared to other examples in order to obtain powder without agglomeration. The operating conditions and physical properties of the powder are shown in Table-3 and Table-
4 and Table 5. Comparative Examples 5 to 6 In Comparative Example 1, powder was obtained in the same manner as in Comparative Example 1, except that the raw material slurries obtained in Reference Examples 2-(7) and 2-(10) were used as the raw material slurry. The physical properties of the obtained powder are shown in Tables 4 and 5. Comparative Examples 7-8 Reference Example 2 was used as the raw material slurry in Example 1.
- Each powder was obtained in the same manner as in Example 1, except that the raw material slurries obtained in (12) and (13) were used. However, in both cases, fine particles were stuck inside the long tube, so 1.
I couldn't drive for more than an hour. The operating conditions and physical properties of the powder are shown in Tables 3 and 4. Example 10 Reference example 2 as raw material slurry in Example 1
− Proceed in the same manner except using the slurry obtained in (15).
Silica powder was produced. Under the operating conditions shown in Table 3, the dispersibility of the powder was good, but
If the feed rate of raw material slurry is 1.3 times that rate,
The dispersibility of the powder became poor. However, continuous operation was possible even in that case. The physical properties of the powder are shown in Tables 4 and 5. Examples 11 to 19 Reference example 2 was used as the raw material slurry in Example 1.
- Each powder was produced in the same manner as in Example 1, except that each raw material slurry obtained in (16) to (24) was used. In each example, it was found that there was no trouble even after 5 hours of continuous operation, and that even longer operation was possible. The operating conditions and physical properties of the powders are shown in Tables 3, 4, and 5. Comparative Examples 9, 10 Reference Example 2 was used as the raw material slurry in Comparative Example 1.
Silica powder was obtained in the same manner as in Comparative Example 1, except that the slurry obtained in -(17) or 2-(18) was used. The physical properties of the powder are shown in Tables 4 and 5. Example 20 The silica spherical fine particle powder obtained in Example 11 was
A porous powder of the fine particles was produced by firing at 400° C. for 5 hours in an air atmosphere. The powder had almost no agglomerated particles and had excellent dispersibility. The results are shown in Table-6. Examples 21 to 24 The spherical fine particles of silica, alumina, zirconia, and titania obtained in Examples 13 to 16 were used in Example 20.
Each porous powder was produced by firing in the same manner as above. The results are shown in Table-6. Comparative Example 11 The silica spherical fine particle powder obtained in Comparative Example 10 was fired in the same manner as in Example 20. The results are shown in Table-6.

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Claims (1)

[Scope of Claims] 1. A method for producing a powder of inorganic fine particles that has better dispersibility in various solvents than a slurry of inorganic fine particles containing water in a solvent, in which (A) is added to the slurry.
methanol and (B) an organic compound whose solubility in water at 20°C is 1.0% by weight or more and which can be azeotropically distilled with water;
One end of a tube capable of externally heating a raw material slurry comprising at least one organic compound selected from the group consisting of organic compounds having an azeotropic composition of water of 4.0% by weight or more in a component azeotropic mixture. is a raw material slurry supply port, and the other end is a device for separating steam and powder held at reduced pressure, and a powder collection chamber is connected to the separation device. A method for producing a powder of inorganic fine particles, which comprises inorganic fine particle powder. 2 If the organic compound is methanol (A), the amount of the organic compound to be allowed to coexist is 1.0 times or more by weight the amount of water contained in the slurry, and if the organic compound is an organic compound (B), the amount of water contained in the slurry is 2. The method according to claim 1, wherein the amount of the organic compound (B) is 0.6 times or more by weight the amount of the organic compound (B) calculated to form a two-component azeotrope composition with respect to the amount of water contained. 3. The method according to claim 1, wherein the organic compound (B) has a normal pressure boiling point of 120°C or less. 4. The method according to claim 1, wherein the organic compound (B) has a normal pressure boiling point of 100°C or less. 5. The method according to claim 1, wherein the inorganic fine particle slurry is a metal oxide slurry obtained by a wet synthesis method, and the inorganic fine particle powder is a metal oxide fine particle powder. 6. The method according to claim 5, wherein the metal oxide fine particle slurry is a slurry obtained by hydrolyzing and condensing an organometallic compound capable of hydrolysis and condensation in an organic solvent in the presence of water exceeding the hydrolysis equivalent. . 7. The method according to claim 5, wherein the slurry obtained by hydrolysis and condensation is heated and concentrated to obtain a slurry having a fine particle concentration of 10 to 40% by weight. 8 The fine particles in the powder are spherical, and the average particle size is
The method according to claim 6, wherein the particle size is in the range of 0.1 to 30 μm and the coefficient of variation of the particle size is in the range of 2 to 30%. 9. The method according to claim 6, wherein the organometallic compound is an alkoxy compound. 10 The alkoxy compound has the general formula I R ¹ _n M (OR ² ) _o (I) (where M is a metal element, R ¹ is a hydrogen atom, an alkyl group having up to 10 carbon atoms, which may have a substituent, or an aryl group) , and at least one group selected from the group consisting of unsaturated aliphatic residues, R ² represents an alkyl group, m is 0 or a positive integer, n is an integer of 1 or more, and m + n = metal 10. The method according to claim 9, which satisfies the valence of element M. Furthermore, m R ¹ may be different, and the same applies to n R ² . 11. The method according to claim 10, wherein the metal element is at least one selected from the group consisting of silicon, titanium, zirconium, and aluminum. 12 Metal oxide fine particles include silica, titania,
The method according to claim 5, wherein the main component is at least one selected from the group consisting of zirconia and alumina. 13. The method according to claim 1, wherein the water content in the raw material slurry is 3 to 30% by weight. 14 By coexisting in the raw material slurry a compound (D) having a group that can react with the surface of the inorganic fine particles, the inorganic fine particle powder is organicized by bonding the compound (D) to the surface of the fine particles. 2. The method of claim 1. 15. The method according to claim 14, wherein the compound (D) is an organic compound having at least one hydroxyl group in its molecule. 16. The method according to claim 14, wherein the compound (D) is a coupling agent. 17. The method according to claim 15, wherein the amount of the organic compound coexisting is 0.01 or more in weight ratio to the fine particles in the raw material slurry. 18. The method according to claim 16, wherein the amount of the coupling agent coexisting is in the range of 0.001 to 0.1 in weight ratio to the fine particles in the raw material slurry. 19. The method according to claim 15, wherein the organic compound is methanol (A) or an organic compound (B). 20. The method of claim 16, wherein the coupling agent is a silane, titanate or aluminate coupling agent. 21 A claim in which an organic compound having at least one hydroxyl group in the molecule is made to coexist in the raw material slurry of the metal oxide fine particles, so that the organic compound is bonded to the surface of the fine particle powder. Fine particles obtained by firing the powder obtained by the method described in Item 6 at a temperature higher than the temperature at which the bound organic compound decomposes are spherical,
The average particle size is in the range of 0.1 to 30 μm, the coefficient of variation of the particle size is in the range of 2 to 30%, and the general formula () S×d×ρ>30 () (where S is BET The specific surface area (m ² /g) of the fine particle powder measured by the method, d represents the number average particle diameter (m) measured by electron microscopy, and ρ represents the density (g / m ³ ) of the fine particle powder. ) A method for producing microparticle powder of porous metal oxide with excellent dispersibility that satisfies the following. 22. The method according to claim 21, wherein the organic compound has two or more carbon atoms. 23. The method according to claim 21, wherein the firing temperature is in the range of 300 to 800°C. 24 Claim 1 further comprising an organic compound (C) having a solubility of water in the organic compound at 20°C of 1.0% by weight or more and a boiling point in the range of 105 to 300°C at normal pressure. The method described in. 25 Organic compounds (A) and/or (B) to coexist
When the organic compound is methanol (A), the amount is 1.0 times or more by weight the amount of water contained in the slurry,
In addition, if the organic compound is an organic compound (B), the amount of the organic compound (B) calculated to have a binary azeotrope composition with respect to the amount of water contained in the slurry.
25. The method according to claim 24, wherein the amount is 0.6 times or more by weight. 26. The method according to claim 24, wherein the organic compound (B) has a normal pressure boiling point of 120°C or less. 27. The method according to claim 24, wherein the organic compound (B) has a normal pressure boiling point of 100°C or less. 28. The method according to claim 24, wherein the inorganic fine particle slurry is a metal oxide slurry obtained by a wet synthesis method, and the inorganic fine particle powder is a metal oxide fine particle powder. 29. The method according to claim 28, wherein the metal oxide fine particle slurry is a slurry obtained by hydrolyzing and condensing an organometallic compound capable of hydrolysis and condensation in an organic solvent in the presence of water exceeding the hydrolysis equivalent. . 30. The method according to claim 28, wherein the slurry obtained by hydrolysis and condensation is heated and condensed to obtain a slurry having a fine particle concentration of 10 to 40% by weight. 31. The method according to claim 29, wherein the fine particles in the powder are spherical, have an average particle diameter in the range of 0.1 to 30 μm, and have a coefficient of variation of the particle diameter in the range of 2 to 30%. 32. The method according to claim 29, wherein the organometallic compound is an alkoxy compound. 33 Alkoxy compounds have the general formula I R ¹ _n M (OR ² ) _o (I) (where M is a metal element, R ¹ is a hydrogen atom, an alkyl group having up to 10 carbon atoms, which may have a substituent, or an aryl group) , and at least one group selected from the group consisting of unsaturated aliphatic residues, R ² represents an alkyl group, m is 0 or a positive integer, n is an integer of 1 or more, and m + n = metal 33. The method according to claim 32, which satisfies the valence of element M. Furthermore, m R ¹ may be different, and the same is true for n R ² . 34. The method according to claim 33, wherein the metal element is at least one selected from the group consisting of silicon, titanium, zirconium, and aluminum. 35 Metal oxide fine particles include silica, titania,
The method according to claim 28, wherein the main component is at least one selected from the group consisting of zirconia and alumina. 36. The method according to claim 24, wherein the water content in the raw material slurry is 3 to 30% by weight. 37 Inorganic fine particle powder is organicized by bonding the compound (D) to the surface of the fine particles by coexisting in the raw material slurry a compound (D) having a group capable of reacting with the surface of the fine inorganic particles. 25. The method of claim 24. 38. The method according to claim 37, wherein the compound (D) is an organic compound having at least one hydroxyl group in its molecule. 39. The method according to claim 37, wherein the compound (D) is a coupling agent. 40. The method according to claim 38, wherein the amount of the organic compound coexisting is 0.01 or more in weight ratio to the fine particles in the raw material slurry. 41. The method according to claim 39, wherein the amount of the coupling agent coexisting is in the range of 0.001 to 0.1 in weight ratio to the fine particles in the raw material slurry. 42. The method according to claim 38, wherein the organic compound is an organic compound (C). 43. The method of claim 39, wherein the coupling agent is a silane, titanate or aluminate coupling agent. 44 A claim in which an organic compound having at least one hydroxyl group in the molecule is made to coexist in the raw material slurry of the metal oxide fine particles, so that the organic compound is bonded to the surface of the fine particle powder. Fine particles obtained by firing the powder obtained by the method described in Item 29 at a temperature higher than the temperature at which the bound organic compound decomposes are spherical and have an average particle size in the range of 0.1 to 30 μm. can be,
The coefficient of variation of the particle size is in the range of 2 to 30%,
Moreover, the general formula () S×d×ρ>30 () (where S is the specific surface area (m ² /g) of the fine particle powder measured by the BET method, and d is the number average particle diameter measured by electron microscopy. (m) and ρ represent the density (g/m ³ ) of the fine particle powder, respectively) and have excellent dispersibility. 45. The method according to claim 44, wherein the organic compound has two or more carbon atoms. 46. The method according to claim 44, wherein the firing temperature is in the range of 300 to 800°C.