JP2001064009A - Inorganic micro-structure and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a porous body or multilayered film having a desired form, narrow particle size distribution or pore size distribution by allowing a solution containing sol obtained by hydrolyzing a metal compound and an amphiphilic organic compound to gel and then heat treating the obtained gel so that the particles having a specified size are obtained. SOLUTION: The inorganic micro-structure is composed of particles having particle size of 10 nm to 1 μm and is obtained by allowing sol in a solution to gel and then heat treating the obtained gel. The solution containing sol is obtained by mixing a solution of a hydrolyzable metal compound or aqueous sol obtained by hydrolyzing a metal compound and a solution which is obtained by forming micelle of an amphiphilic organic compound in an organic solvent. Or, the solution containing sol is obtained by mixing a solution, which is obtained by dissolving the amphiphilic compound into an aqueous solution of a hydrolyzable metal compound or the aqueous sol obtained by hydrolyzing the metal compound, with an organic solvent in order to form W/O-type emulsion containing the aqueous sol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an inorganic microstructure comprising submicron sized particles, a porous body having a large number of submicron sized pores, or a multilayer film having a submicron sized layer. Using a metal compound that can be hydrolyzed such as a metal alkoxide or a metal salt as a starting material, using an amphipathic substance such as a surfactant, and using an emulsion formation technique and a sol-gel method, The present invention relates to a method for producing an inorganic microstructure.

[0002]

2. Description of the Related Art Conventionally, as a method for producing particles, porous materials or multilayer films having an inorganic microstructure, for example, (A) an emulsion of an inorganic aqueous solution is formed in an organic solvent and then precipitated by an interfacial reaction. To obtain spherical particles by forming
And (B) a method of forming a microemulsion of water in an alkoxide solution and mixing with a microemulsion of an aqueous catalyst solution to obtain ultrafine silica spherical particles (Langmuir Vo).
l. 13, p. 6400 (1997)), (C)
A method for obtaining a porous body by allowing a long chain quaternary ammonium salt to be contained in a solution of a Si alkoxide and gelling the same (Science, Vol. 267, SCIENCE).
p. 1138 (1995) etc.), (D) hydrolysis of metal alkoxide in a solution of a nonionic surfactant, gelation, and heat treatment to make it porous (JP-A-10-1)
82261), and (E) a method of preparing a multilayer structure using a bilayer membrane (Journal of American Chemical Society)
American Chemical Society
y) Vol. 103, p. 5401 (1981)).

[0003]

However, each of the above-mentioned conventional methods has the following problems. That is, in the method (A), the types of metals that can be prepared in the inorganic aqueous solution are limited.
Although porous particles can be produced, particles having a particle size of 1 μm or less cannot be obtained, or it is difficult. In the method (B), monodispersed silica particles having a particle size of 10 nm to 1.5 μm can be obtained, but fine particles other than silica cannot be obtained, or it is difficult. Further, the obtained fine particles are not porous. In the method (C), the obtained porous body has a fine pore diameter of 10 nm or less, and 10 nm to 1 μm.
The formation of pores in the range of m cannot be controlled or is difficult, and the resulting porous body is in the form of flakes. In the method (D), production of a porous body having a fine pore diameter of only 1 μm or less is uncontrollable or difficult. In the method (E), the types of substances forming the bilayer film are limited, and the obtained layered structure is in a flake shape.

The present invention has been made in view of the above circumstances, and the type of metal of the metal compound as a starting material is not limited, and the particles having a particle diameter of 10 nm to 1 μm and the fine pore diameter are not limited to 10 nm to 1 μm. A porous body having a thickness of 10 nm to 1 μm and a multilayer film having a thickness of each layer of 10 nm to 1 μm can be obtained, and porous particles can be obtained.
It is also possible to obtain a porous body or a multilayer film having a desired shape, and further provides a method for producing an inorganic microstructure in which a narrow particle size distribution and a fine pore size distribution are obtained, and variations in thickness of each layer are reduced. It is another object of the present invention to provide an inorganic microstructure having excellent characteristics obtained by the manufacturing method.

[0005]

The inorganic microstructure according to the first aspect of the present invention is characterized in that a gel containing a solution containing a sol obtained by hydrolyzing a metal compound and an amphiphilic organic compound is gelled and then gelled. It is obtained by heat treatment, and is formed of particles having a particle size of 10 nm to 1 μm. According to a second aspect of the present invention, there is provided the inorganic microstructure according to the first aspect, wherein the particles are porous.

The invention according to claim 3 is obtained by gelling a solution containing a sol obtained by hydrolyzing a metal compound and an amphiphilic organic compound, and then heating the gel, It is formed of a porous body having a large number of pores having a pore diameter of 10 nm to 1 μm.

According to a fourth aspect of the present invention, there is provided the inorganic microstructure, wherein a solution containing a sol obtained by hydrolyzing a metal compound and an amphiphilic organic compound is applied to the surface of the substrate to gel the coating film. Is repeated several times and the gel film is subjected to a heat treatment, and the thickness of each layer is 10 nm.
It is formed of a multilayer film having a thickness of about 1 μm.

According to a fifth aspect of the present invention, in the method for producing an inorganic microstructure according to the first or second aspect, the aqueous solution of the hydrolyzable metal compound or the metal compound is hydrolyzed. An aqueous sol and a solution in which micelles of an amphipathic organic compound are formed in an organic solvent are mixed, or an aqueous solution of a hydrolyzable metal compound or an aqueous sol obtained by hydrolyzing a metal compound. A step of mixing a solution in which an amphiphilic organic compound is dissolved and an organic solvent to form a W / O emulsion containing an aqueous sol; and gelling the sol in the solution obtained in this step. A step of heating the gel obtained in this step.

According to a sixth aspect of the present invention, in the method for producing an inorganic microstructure according to the first or second aspect, a solution of a hydrolyzable metal compound or a metal compound is hydrolyzed. A solvent-based sol and a solution of a hydrolyzable metal compound or a solvent-based sol obtained by hydrolyzing a metal compound by mixing an aqueous solution in which micelles of an amphiphilic organic compound are formed in water. Mixing a solution in which an amphiphilic organic compound is dissolved with water to form an O / W emulsion containing a solvent-based sol, and gelling the sol in the solution obtained in this step. A step of heating the gel obtained in this step.

[0010] According to a seventh aspect of the present invention, in the method for producing an inorganic microstructure according to the third aspect, a solution of a hydrolyzable metal compound or a solvent-based sol obtained by hydrolyzing a metal compound. A solution in which micelles of an amphipathic organic compound are formed and water, or a solution of a hydrolyzable metal compound or a solvent-based sol obtained by hydrolyzing a metal compound; Forming a W / O-type emulsion containing a solvent-based sol by mixing water in which a reactive organic compound is dissolved, a step of gelling the sol in the solution obtained in this step, and a step of gelling the sol in the solution obtained in this step. And heat-treating the gel obtained in the above.

[0011] According to an eighth aspect of the present invention, in the method for producing an inorganic microstructure according to the third aspect, an aqueous solution of a hydrolyzable metal compound or an aqueous sol obtained by hydrolyzing a metal compound is used. A solution in which micelles of an amphipathic organic compound were formed and an organic solvent were mixed,
Alternatively, an aqueous sol obtained by hydrolyzing an aqueous solution of a hydrolyzable metal compound or a metal compound is mixed with an organic solvent in which an amphiphilic organic compound is dissolved, and an O / W containing an aqueous sol is mixed. A step of forming a mold emulsion, a step of gelling the sol in the solution obtained in this step, and a step of heat-treating the gel obtained in this step.

According to a ninth aspect of the present invention, in the method for producing an inorganic microstructure according to the fourth aspect, there is provided an aqueous sol obtained by hydrolyzing an aqueous solution of a hydrolyzable metal compound or a metal compound. Mixed with a solution forming micelles of an amphiphilic organic compound in an organic solvent,
Alternatively, an aqueous solution of a hydrolyzable metal compound or a solution in which an amphiphilic organic compound is dissolved in an aqueous sol obtained by hydrolyzing a metal compound, and an organic solvent are mixed, and an emulsion containing an aqueous sol is mixed. Forming a;
Applying the solution obtained in this step to the surface of the substrate to gel the sol in the coating film, and repeating this coating and gelling operation a plurality of times to form a gel film of a plurality of layers; and And subjecting the gel film obtained in the above to a heat treatment.

[0013] According to the production method of each of the inventions according to claims 5 to 9, the emulsion is used as a template,
Particles, pores of a porous body or each layer of a multilayer film are formed,
The particles constituting the inorganic microstructure of the invention according to claim 1, the porous bodies constituting the inorganic microstructure of the invention according to claim 3, or the multilayers constituting the inorganic microstructure of the invention according to claim 4 A film is obtained. Then, the obtained particles become porous like the inorganic microstructure of the invention according to claim 2, and the porous body and the multilayer film can have a desired shape. Furthermore, the obtained particles and porous body have a narrow particle size distribution and a narrow pore size distribution, and the multilayer film has small variations in thickness of each layer.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

The inorganic microstructure according to the present invention has a particle diameter of 10 nm to 1 μm and a pore diameter of 10 nm to 1 nm.
It is composed of a porous body having a large number of pores of 1 μm or a multilayer film in which each layer has a thickness of 10 nm to 1 μm. These inorganic microstructures use a metal compound that can be hydrolyzed, such as a metal alkoxide, a metal salt, or a metal complex, as a starting material, and use an amphiphilic substance such as a surfactant to form an emulsion. It is manufactured using a sol-gel method.

That is, to produce particles, first,
An aqueous sol obtained by hydrolyzing an aqueous solution or a metal compound of a hydrolyzable metal compound is mixed with a solution in which a micelle of an amphiphilic organic compound is formed in an organic solvent, and the aqueous sol containing the aqueous sol is mixed. An aqueous solution of a hydrolyzable metal compound or a solution in which an amphiphilic organic compound is dissolved in an aqueous sol obtained by hydrolyzing a metal compound, and an organic solvent; Are mixed to form a W / O emulsion containing an aqueous sol, and a solution of a hydrolyzable metal compound or a solvent sol obtained by hydrolyzing a metal compound, and an amphiphilic organic compound in water. To form an O / W type (oil-in-water) emulsion containing a solvent-based sol, or a solution or metallization of a hydrolyzable metal compound. A solution obtained by dissolving an amphiphilic organic compound to the sol of the solvent system obtained by hydrolyzing an object,
By mixing with water, an O / W emulsion containing a solvent-based sol is formed. Next, a catalyst (ammonia, inorganic electrolyte salt, acid, or the like) or a solution in which the catalyst is dissolved in water or an organic solvent is added to the emulsion solution to gel the sol. The degree of shrinkage of the particles during this gelation is slight. Therefore, since gelation is performed while maintaining the original particle size to some extent, the water or solvent portion remaining in the gel becomes pores, and finally porous particles are obtained. . After the gelation, the organic solvent and water are evaporated and removed by a drying treatment. At this time, the particles slightly shrink. Thereafter, the obtained gel is subjected to a heat treatment to thermally decompose the organic substance and the like, and the metal oxide gel is fired. With this, the emulsion is used as a template, the particle size is 10 nm to 1 μm, the material is porous,
Particles of a metal oxide having a narrow particle size distribution are obtained.

In order to produce a porous body having a large number of pores, an amphiphilic organic compound is first dissolved in a solution of a hydrolyzable metal compound or a solvent-based sol obtained by hydrolyzing a metal compound. A solution in which a micelle of a compound is formed is mixed with water to form a W / O emulsion containing a solvent-based sol, and a solution of a hydrolyzable metal compound or a solvent obtained by hydrolyzing a metal compound. A water-based emulsion containing a solvent-based sol is formed by mixing a water-based sol and water in which an amphiphilic organic compound is dissolved, and hydrolyzing an aqueous solution of a hydrolyzable metal compound or a metal compound. A solution in which micelles of an amphipathic organic compound are formed in an aqueous sol obtained by mixing with an organic solvent to form an O / W emulsion containing an aqueous sol, or Sol aqueous obtained an aqueous solution or a metal compound of group compound is hydrolyzed by combining an organic solvent dissolving the amphiphilic organic compound, to form an O / W type emulsion containing a sol of water. Next, a catalyst (ammonia, inorganic electrolyte salt, acid, or the like) or a solution in which the catalyst is dissolved in water or an organic solvent is added to the emulsion solution to gel the sol. The degree of shrinkage of the solid during the gelation is slight. After the gelation, the organic solvent and water are evaporated and removed by a drying treatment. Thereafter, the obtained gel is subjected to a heat treatment to thermally decompose the organic substance and the like, and the metal oxide gel is fired. Thus, a large number of pores having a pore diameter of 10 nm to 1 μm are formed in a matrix using the emulsion as a template, and a porous body made of a metal oxide having a narrow pore diameter distribution is obtained.

In order to produce a multilayer film, first, an aqueous solution of a hydrolyzable metal compound or an aqueous sol obtained by hydrolyzing a metal compound and micelles of an amphiphilic organic compound in an organic solvent are used. Mixing with the formed solution to form an emulsion containing an aqueous sol, or
An aqueous solution of a hydrolyzable metal compound or a solution in which an amphiphilic organic compound is dissolved in an aqueous sol obtained by hydrolyzing a metal compound is mixed with an organic solvent to form an emulsion containing an aqueous sol. I do. Next, an emulsion solution containing an aqueous sol is applied to the surface of the hydrophobic substrate and dried. By this coating operation, a coating film in which the hydrophobic groups of the amphiphilic organic compound are oriented on the interface side with the substrate and on the interface side with the air is obtained, and the organic solvent and water are evaporated and removed from the coating film by drying. Then, a gel film is formed with shrinkage. After this coating and drying operation is repeated a plurality of times, the gel film is subjected to heat treatment to thermally decompose the organic substance and the like, and the metal oxide gel is fired. As a result, a multilayer film made of a metal oxide having a thickness of each layer of 10 nm to 1 μm and a small variation in the thickness of each layer is obtained.

In each of the above production methods, the metal compound as a starting material may be any hydrolyzable metal compound, such as a metal alkoxide or a metal salt. The type of metal is not particularly limited, and Li, Be, B,
Na, Mg, Al, Si, K, Ca, Sc, Ti, V,
Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, G
e, Rb, Sr, Y, Zr, Nb, Mo, Cd, In,
Sn, Sb, Cs, Ba, La, Hf, Ta, W, T
1, Pb, Bi, Ce, Pr, Nd, Pm, Sm, E
u, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu
Compounds of such metals can be used, and the starting materials may be a combination of two or more metal compounds. As the metal alkoxide, one having an alkoxyl group having 1 to 5 carbon atoms is usually used, and more preferably one having an alkoxyl group having 2 to 4 carbon atoms is used. As the metal salt, an inorganic salt such as nitrate or chloride, or an organic acid salt such as acetate or oxalate is used.

The method for preparing the sol using the above-mentioned metal compound as a raw material is not particularly limited. Solvents for dissolving metal alkoxides and metal salts include methanol,
Alcohols such as ethanol, propanol and butanol, organic acid esters such as ethyl acetate, acetonitrile, ketones such as acetone and methyl ethyl ketone, cycloethers such as tetrahydrafuran (THF) and dioxane, formamide (FA), N, N- Acid amides such as dimethylformamide (DMF), hydrocarbons, and aromatics such as toluene are used. An acid catalyst and / or a base catalyst may be used for the hydrolysis of a solution containing a metal alkoxide or a metal salt, and a mineral acid such as hydrochloric acid, an organic acid such as acetic acid, or aqueous ammonia is used. .

The method for preparing the sol will be described in a more specific example. A metal alkoxide is added to an alcohol or an aromatic hydrocarbon in an amount of 0.01 M to 1 M, more preferably 0.1 M to
Dissolve to a concentration of 0.5M. To this alkoxide solution, add water or 0.01M to 0.5M, more preferably 0.05M to 0.2M aqueous ammonia or 0.1M to 0.2M aqueous ammonia.
01M to 1M, more preferably 0.05M to 0.2M hydrochloric acid is added at a ratio of 2 to 200M / metal alkoxide to cause hydrolysis. Alternatively, 0.01 mole of metal alkoxide is added to 10 ml to 1,000 ml, more preferably 20 ml to 100 ml of water or 0.1 M to
It is added to 2.0M, more preferably 0.5M to 1.5M hydrochloric acid to cause hydrolysis.

As the amphiphilic organic compound, nonionic, cationic and anionic surfactants are used. This amphiphilic organic compound is added to water or an organic solvent at a ratio of 10% to 99%, preferably 40% to 80% to form micelles in water or an organic solvent. As the organic solvent for dissolving the amphiphilic organic compound, an alcohol, an aromatic hydrocarbon, a long-chain hydrocarbon, or the like is used. The temperature and time of the heat treatment of the gel vary depending on the type of the metal oxide.
Heat treatment at a temperature of 00 ° C. for several hours.

[0023]

Next, a specific embodiment to which the present invention is applied will be described.

Example 1 A solution is prepared by dissolving 15 g of polyoxyethylene sorbitan trioleate in 30 g of decanol. Also, 10 ml of tetraethoxysilane was dissolved in 150 ml of ethanol, and this solution was added to a mixed solution of 150 ml of ethanol, 150 ml of water and 0.28 g of ammonia to hydrolyze the tetraethoxysilane, and then concentrated by ethanol. Is removed to prepare a SiO ₂ sol (solution B).

The solution A and the solution B are mixed, 5 ml of a 1.5 M NH ₄ Cl aqueous solution is added to the mixture, and the mixture is allowed to stand overnight. Then, a filtration operation is performed, and the filtrate is washed with ethanol and dried. Then, the obtained solid is heated at a temperature of 700 ° C. for 3 hours. Thereby, the particle size is 300 n.
As a result, spherical SiO ₂ particles having a porosity of 50% were obtained.

Example 2 10 g of sorbitan monooleate was dissolved in 10 g of liquid paraffin, and this solution was mixed with the above solution B. 1.0 M NH ₄ C was added to this mixed solution.
After adding 10 g of an aqueous solution and allowing the mixture to stand overnight, a filtration operation is performed, and the filtrate is washed with ethanol and dried. Then, the obtained solid is heated at a temperature of 700 ° C. for 3 hours. As a result, a porous SiO ₂ body having a center fine pore diameter of 50 nm and a porosity of 70% was obtained.

Example 3 5 g of cetyltrimethylammonium bromide is dissolved in the above solution B, and this solution is added to 10 g of toluene to form a W / O type (water-in-oil) emulsion. This emulsion solution is dip-coated on a PET (polyethylene terephthalate) substrate and air-dried. This coating and drying operation is
After repeating 0 times, the substrate is heat-treated at a temperature of 700 ° C. for 3 hours. As a result, an SiO ₂ film in which a SiO ₂ layer having a thickness of about 100 nm was laminated on the substrate was obtained.

[0028]

The inorganic microstructure according to the first aspect of the present invention has a particle size of 10 nm to 1 μm, is porous like the inorganic microstructure of the second aspect, and has a narrow particle size distribution. Cosmetics, CM
P is extremely useful as a material for pigments, dyes, catalysts and the like in printing inks.

The inorganic microstructure according to the third aspect of the present invention comprises a porous body having a large number of fine pores having a fine pore diameter of 10 nm to 1 μm formed in a matrix and having a narrow pore diameter distribution. It is extremely useful as a material for chromatography columns, gas selection membranes, separation membranes, filters, soundproofing materials, anti-vibration materials, sensors and the like.

The inorganic microstructure of the invention according to claim 4 is composed of a multilayer film having a thickness of each layer of 10 nm to 1 μm and a small variation in the thickness of each layer, such as a dielectric multilayer film, a battery electrode, a sensor and the like. It is extremely useful as a material for.

According to the production method of each of the inventions according to claims 5 and 6, regardless of the kind of the metal of the metal compound as a starting material, the particle diameter is 10 nm to 1 μm, porous and narrow in particle diameter distribution. An inorganic microstructure composed of particles having the same is obtained.

According to the manufacturing method of each of the inventions according to the seventh and eighth aspects, an inorganic microstructure comprising a porous body having a fine pore diameter of 10 nm to 1 μm, a narrow pore diameter distribution, and a desired shape can be obtained. Can be

According to the manufacturing method of the ninth aspect,
The thickness of each layer is 10 nm to 1 μm, the thickness of each layer is small, and an inorganic microstructure composed of a multilayer film having a desired film form is obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // B01J 20/10 B01J 20/10 A F-term (reference) 4D006 GA01 GA41 MC03X NA39 NA46 NA51 4G065 AA05 AA06 BA15 BB01 BB02 CA04 CA21 EA10 4G066 AA14D AA22B AA32D AA52D AB01D AB06A AB06D AB18A AC22A BA03 BA05 BA09 BA20 BA22 FA14 FA21 4G072 AA28 AA41 BB05 BB09 CC01 CC05 DD05 DD06 HH30 JJ23 TT11 NN11 PP01 NN11 PP01

Claims (9)

[Claims] 1. A method comprising: gelating a solution containing a sol obtained by hydrolyzing a metal compound and an amphiphilic organic compound; and then subjecting the gel to a heat treatment, wherein particles having a particle size of 10 nm to 1 μm are obtained. Inorganic microstructure. 2. The inorganic microstructure according to claim 1, wherein the particles are porous. 3. A solution containing a sol obtained by hydrolyzing a metal compound and an amphipathic organic compound is gelled, and then the gel is heat-treated, and has a pore diameter of 10 nm to 1 μm.
An inorganic microstructure comprising a porous body having a large number of pores. 4. A step of applying a solution containing a sol obtained by hydrolyzing a metal compound and an amphiphilic organic compound to the surface of a substrate and gelling the coating film a plurality of times, and then heating the gel film. And each layer has a thickness of 10 nm to 1
Inorganic microstructure comprising a multilayer film having a thickness of μm. 5. The method for producing an inorganic microstructure according to claim 1, wherein an aqueous sol obtained by hydrolyzing an aqueous solution of a hydrolyzable metal compound or a metal compound; The amphiphilic organic compound is mixed with a solution in which a micelle of the amphiphilic organic compound is formed in a solvent, or an aqueous solution of a hydrolyzable metal compound or an aqueous sol obtained by hydrolyzing the metal compound. Mixing the dissolved solution with an organic solvent to form a W / O emulsion containing an aqueous sol; gelling the sol in the solution obtained in this step; Heating the obtained gel. A method for producing an inorganic microstructure, comprising: 6. The method for producing an inorganic microstructure according to claim 1 or 2, wherein a solution of a hydrolyzable metal compound or a solvent-based sol obtained by hydrolyzing the metal compound; Mixing with an aqueous solution forming micelles of an amphiphilic organic compound in water,
Alternatively, a solution of a hydrolyzable metal compound or a solution in which an amphipathic organic compound is dissolved in a solvent-based sol obtained by hydrolyzing a metal compound, and a mixture of water and a solvent-based sol are included. An inorganic material comprising: a step of forming an O / W emulsion; a step of gelling a sol in a solution obtained in this step; and a step of heat-treating the gel obtained in this step. A method for producing a microstructure. 7. The method for producing an inorganic microstructure according to claim 3, wherein the amphiphilic organic compound is dissolved in a solution of a hydrolyzable metal compound or a solvent-based sol obtained by hydrolyzing the metal compound. A solution in which a micelle of a compound is formed is mixed with water, or a solution of a hydrolyzable metal compound or a solvent-based sol obtained by hydrolyzing a metal compound, and an amphiphilic organic compound are dissolved. Forming a W / O emulsion containing a solvent-based sol by mixing the sol in the solution obtained in this step; and forming a gel in the solution obtained in this step. And b. Performing a heat treatment. 8. The method for producing an inorganic microstructure according to claim 3, wherein the amphiphilic organic compound is contained in an aqueous solution of a hydrolyzable metal compound or in an aqueous sol obtained by hydrolyzing a metal compound. A solution in which micelles were formed and an organic solvent were mixed, or an aqueous sol obtained by hydrolyzing an aqueous solution of a hydrolyzable metal compound or a metal compound, and an amphiphilic organic compound were dissolved. Mixing an organic solvent to form an O / W emulsion containing an aqueous sol; gelling the sol in the solution obtained in this step; heating the gel obtained in this step A method of producing an inorganic microstructure. 9. The method for producing an inorganic microstructure according to claim 4, wherein the aqueous sol obtained by hydrolyzing the metal compound or an aqueous solution of a hydrolyzable metal compound is mixed with an aqueous sol obtained by hydrolyzing the metal compound. A solution in which an amphiphilic organic compound is dissolved in an aqueous sol obtained by mixing an aqueous solution of a hydrolyzable metal compound or an aqueous sol obtained by hydrolyzing a metal compound, And mixing an organic solvent to form an emulsion containing an aqueous sol; applying the solution obtained in this step to the surface of a substrate to gel the sol in the coating film; A step of forming a plurality of layers of gel films by repeating the conversion operation a plurality of times, and a step of heat-treating the gel films obtained in this step. Production method.