JP4839785B2 - Method for producing metal oxide film - Google Patents

Description

  The present invention relates to a method for producing a metal oxide film which is a wet coat and can obtain a dense metal oxide film with respect to a substrate having a structure portion.

  Conventionally, it has been known that metal oxide films exhibit various excellent physical properties. Taking advantage of these properties, metal oxide films have been used in a wide range of fields such as transparent conductive films, optical thin films, and fuel cell electrolytes. As a method for producing such a metal oxide film, for example, a sol-gel method, a sputtering method, a CVD method, a PVD method, a printing method and the like are known.

  A problem in such a method for producing a metal oxide film is that it is difficult to provide a uniform metal oxide film on a substrate having a structure. For example, in the sputtering method, shape followability is poor due to its principle, and in the printing method, it is difficult to form a film on a fine structure portion smaller than the ceramic fine particles contained in the ink. The CVD method, which is said to be relatively excellent in shape followability, is effective for structural parts such as shallow grooves with simple shapes, but uniform metal oxidation for complex structural parts. It was difficult to provide a material film. In addition, wet coating such as sol-gel method is an inexpensive method, but it is difficult not only to form a film on a substrate having a complicated structure, but also to obtain a dense metal oxide film. there were.

  In order to solve such a problem, a soft solution process in which a metal oxide film is directly formed on a substrate from a solution has been proposed (Non-patent Document 1). In such a soft solution process, since the substrate is brought into contact with the metal oxide film forming solution, even if the substrate has a structure part, the solution can easily enter the structure part, and the uniform solution Advantageous metal oxide films can be obtained.

As an attempt to use such a soft solution process, for example, in Patent Document 1, a reaction solution containing a constituent element of a thin film to be formed between an anode electrode and a cathode electrode to which a predetermined voltage is applied is specified. A method of forming a thin film by flowing at a flow rate is disclosed.
However, the method in Patent Document 1 has a problem that the substrate is limited to a conductor, and the obtained thin film has a coarse particle quality and a dense metal oxide film cannot be obtained. Furthermore, there is a problem that the metal oxide film obtained is a thin film and a metal oxide film having a sufficient film thickness cannot be obtained.

  On the other hand, spray pyrolysis has been proposed as another method for obtaining a metal oxide film (Patent Document 2 and Patent Document 3). The spray pyrolysis method is a method in which a metal oxide film is obtained by spraying a solution containing a metal source constituting the metal oxide film onto a high temperature substrate, and a substrate heated to about 500 ° C. is usually used. Since it is used, the solvent instantly evaporates and the metal source undergoes a thermal decomposition reaction, so that the metal oxide film can be obtained in a short and simplified process.

As a research on such spray pyrolysis method, for example, in Patent Document 2, a raw material solution is prepared by adding hydrogen peroxide or aluminum acetylacetonate to a solution containing a TiO ₂ precursor, and the temperature is as high as about 500 ° C. A method is disclosed in which a TiO ₂ precursor is thermally decomposed into TiO ₂ by intermittently spraying the raw material solution onto a held substrate to obtain a porous TiO ₂ thin film on the substrate. Further, for example, Patent Document 3 is a method for obtaining a porous TiO ₂ thin film by a thermal decomposition spray method as in Patent Document 2, but by adding a solution obtained by adding a soluble titanium compound to a raw material solution, TiO ₂ is obtained. ₍₂₎ The adhesion between the thin film and the substrate was improved.

  As described above, although the spray pyrolysis method is a method that can obtain a metal oxide film in a short time and a simplified process, it is easily influenced by the surface of the base material, and particularly the crystallinity of the surface of the base material For example, when the base material has a complicated structure or is a porous material, a metal oxide film having a dense and excellent crystallinity cannot be obtained. there were.

Resources and materials Vol. 116 p. 649-655 (2000) Japanese Patent No. 3353070 JP 2002-145615 A JP 2003-176130 A

  The present invention has been made in view of the above problems, and is an inexpensive Wet coat using a solution for forming a metal oxide film, and includes a substrate having a structural portion, such as a porous substrate or a porous film. It is a main object to provide a method for producing a metal oxide film that can obtain a metal oxide film that is uniform, dense, and has a sufficient film thickness without being affected by the surface crystallinity of the substrate having the same. It is the purpose.

  In order to solve the above-mentioned problems, a metal salt or metal complex as a metal source, a solution for forming a first metal oxide film in which at least one of an oxidizing agent and a reducing agent is dissolved, and a substrate are brought into contact with each other. A first metal oxide film forming step of forming a first metal oxide film on the substrate, and heating the substrate including the first metal oxide film to a temperature equal to or higher than a metal oxide film forming temperature, A method for producing a metal oxide film comprising a second metal oxide film forming step of obtaining a second metal oxide film by contacting with a solution for forming a second metal oxide film in which a metal salt or metal complex is dissolved as a source I will provide a.

  According to the present invention, in the first metal oxide film forming step, by using the first metal oxide film forming solution, for example, even when the substrate has a structure part, the solution has a structure. Since it can penetrate | invade easily in a part, a 1st metal oxide film can be obtained in a structure part inside or a surface. In the second metal oxide film forming step, the substrate provided with the first metal oxide film is heated to a temperature equal to or higher than the metal oxide film forming temperature and brought into contact with the second metal oxide film forming solution. By doing so, a second metal oxide film can be provided on the first metal oxide film, and as a result, a metal oxide film having a uniform, dense and sufficient film thickness can be obtained. In addition, by changing the type of metal source contained in the first metal oxide film forming solution and the second metal oxide film forming solution, for example, different types of metal oxides can be used in the porous material inside and on the surface portion. A physical film can be formed.

  Moreover, in the said invention, when making the said 1st metal oxide film formation solution and the said base material contact, it is preferable to mix oxidizing gas, and especially said oxidizing gas is oxygen or ozone. It is more preferable. This is because the generation rate of the first metal oxide film can be improved by mixing the oxidizing gas.

  Moreover, in the said invention, when making the said 1st metal oxide film formation solution and the said base material contact, it is preferable to irradiate with an ultraviolet-ray. It is considered that the reaction corresponding to the electrolysis of water can be induced by irradiating with ultraviolet rays. The generated hydroxide ions raise the pH of the first metal oxide film forming solution, and It is because it can be set as the environment where a monometallic oxide film is easy to form. Furthermore, the crystallinity of the obtained first metal oxide film can be improved by irradiating with ultraviolet rays.

  Moreover, in the said invention, it is preferable to make it contact with the base material provided with the said 1st metal oxide film by spraying the said solution for 2nd metal oxide film formation. By spraying the second metal oxide forming solution, the second metal oxide forming solution can be contacted without lowering the temperature of the base material provided with the first metal oxide film. It is.

  Moreover, in the said invention, it is preferable that the said 2nd metal oxide film formation solution contains at least one of an oxidizing agent and a reducing agent. By containing at least one of an oxidizing agent and a reducing agent in the second metal oxide film forming solution, a metal oxide film can be obtained at a lower substrate heating temperature compared to the conventional spray pyrolysis method. Because it can. Further, according to the present invention, even when the oxidizing agent and the reducing agent are used in combination, a metal oxide film can be obtained at a low substrate heating temperature.

  Moreover, in the said invention, it is preferable that the said 2nd metal oxide film formation solution contains hydrogen peroxide or sodium nitrite as an oxidizing agent. This is because the heating temperature of the base material provided with the first metal oxide film can be lowered, and the metal oxide film can be obtained at a lower base material heating temperature as compared with the conventional spray pyrolysis method.

  Moreover, in the said invention, it is preferable that the said 2nd metal oxide film formation solution contains a borane complex as a reducing agent. This is because the heating temperature of the base material provided with the first metal oxide film can be lowered, and the metal oxide film can be obtained at a lower base material heating temperature as compared with the conventional spray pyrolysis method.

  In the above invention, the metal source used for the first metal oxide film forming solution is Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Y, It is preferable to contain at least one metal element selected from the group consisting of Zr, Ag, In, Sn, Ce, Sm, Pb, La, Hf, Sc, Gd, and Ta. Since the metal element has a metal oxide region or a metal hydroxide region in the Pourbaille diagram, it is suitable as a main constituent element of the first metal oxide film.

  In the above invention, the metal source used in the second metal oxide film forming solution is Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Y, Selected from the group consisting of Zr, Ag, In, Sn, Ce, Sm, Pb, La, Hf, Sc, Gd, Ta, Cr, Ga, Sr, Nb, Mo, Pd, Sb, Te, Ba, and W It is preferable to contain at least one metal element. Since the metal element can produce a stable metal oxide, it is suitable as a main constituent element of the second metal oxide film.

  In the above invention, at least one of the first metal oxide film forming solution and the second metal oxide film forming solution is a chlorate ion, a perchlorate ion, a chlorite ion, or a hypochlorite. It is preferable to contain at least one ionic species selected from the group consisting of acid ions, bromate ions, hypobromate ions, nitrate ions, and nitrite ions. The ionic species can generate hydroxide ions by reacting with electrons, raise the pH of the metal oxide film forming solution, and make it easy to form a metal oxide film or the like. Because it can.

  Moreover, in the said invention, it is preferable that the said 2nd metal oxide film formation solution contains ceramic fine particle further. This is because by using the ceramic fine particles, a metal oxide film is formed so as to surround the ceramic fine particles, and a mixed film of different ceramics can be obtained and the volume of the metal oxide film can be increased.

  The present invention has an effect that a metal oxide film having a uniform, dense and sufficient film thickness can be obtained on a substrate having a complicated structure or a substrate made of a porous material.

  Hereinafter, the manufacturing method of the metal oxide film of this invention is demonstrated in detail.

  In the method for producing a metal oxide film of the present invention, a metal salt or metal complex as a metal source, a solution for forming a first metal oxide film in which at least one of an oxidizing agent and a reducing agent is dissolved, and a substrate are contacted A first metal oxide film forming step for forming a first metal oxide film on the base material, and a base material provided with the first metal oxide film up to a temperature equal to or higher than a metal oxide film forming temperature. A second metal oxide film forming step of obtaining a second metal oxide film by heating and contacting with a solution for forming a second metal oxide film in which a metal salt or metal complex is dissolved as a metal source .

In the present invention, for example, a conductive film having a uniform, dense and sufficient film thickness can be applied to a substrate which is a porous material. Specifically, a dense ITO transparent conductive film can be applied to a substrate provided with porous titanium oxide on the surface.
Moreover, in this invention, a nonmetallic property can be provided with respect to the metal base material which performed the fine process with the etching technique, for example. Specifically, it is possible to provide insulation, and it can be used at a higher temperature than the conventional resin insulation method. Furthermore, since the metal oxide film manufactured by such a method has excellent adhesion to the metal substrate and is dense, the conventional insulation method using a resin requires a film thickness of about 10 μm. Even a metal oxide film having a thickness of about 1 μm can provide the same insulating property.
Moreover, in this invention, corrosion resistance can be provided with respect to the metal base material which performed the fine process with the etching technique, for example. Specifically, by forming a metal oxide film that is resistant to acids and alkalis and that has electrical conductivity, it is possible to obtain a usable member even in an environment that cannot be used only with metal. it can. Furthermore, in the present invention, since the colored metal oxide film having the above corrosion resistance can be obtained, it can be used for a member requiring design properties, specifically, a member for measures against acid rain in a building or a plant. it can.
The present invention can also be applied to a resin base material or the like that has been subjected to fine processing. By using the present invention, an inexpensive and easy-to-process resin can be finely processed to impart organic solvent resistance, hydrophilicity, and biocompatibility, so that an organic solvent plant, organic solvent container, biochip, physics and chemistry equipment Can be used in general.

  Next, the manufacturing method of the metal oxide film of this invention is demonstrated using figures. For example, as shown in FIG. 1, in the first metal oxide film forming step, the base material 1 is brought into contact with the first metal oxide film forming solution 2 by immersion (FIG. 1 (a)). 1 is formed with a first metal oxide film 3 (FIG. 1B). Subsequently, in the second metal oxide film formation step, the base material 1 provided with the first metal oxide film 3 is heated to a temperature equal to or higher than the metal oxide film formation temperature, and the second metal oxide film formation solution 4 is brought into contact by spraying with a spray device 5 (FIG. 1C), a second metal oxide film is provided on the first metal oxide film, and as a result, a dense metal oxide film 6 is obtained. It is.

Next, regarding the change in the valence of the metal source in the method for producing a metal oxide film of the present invention, cerium oxide (CeO) from the first and second metal oxide film forming solutions containing cerium ions Ce ³⁺ as the metal source. ₂ ) A case of obtaining a film will be described. In the present invention, cerium oxide (CeO ₂ ) is used from a metal oxide film forming solution containing cerium ions Ce ³⁺ in both the first metal oxide film forming process and the second metal oxide film forming process. Is formed. FIG. 2 is a pool line diagram of cerium. In the present invention, cerium existing as Ce ³⁺ (corresponding to the Ce ³⁺ region in the figure) in the metal oxide film forming solution has a valence of A CeO ₂ film (corresponding to the CeO ₂ region in the figure) is changed. That is, in the present invention, it can be considered that the cerium ions have reached the CeO ₂ region from the Ce ³⁺ region in the figure by the effect of heat or the like. Further, the oxidant, reducing agent, oxidizing gas, ultraviolet light, and the like that are preferably used in the present invention are considered to make the cerium ions in the Ce ³⁺ region more likely to approach the CeO ₂ region as in the case of heating. be able to. From this, it is considered that a metal oxide film can be similarly manufactured by the manufacturing method of the present invention as long as it is a metal element having a similar metal oxide region. Moreover, even if it is a metal element which has a metal hydroxide area | region, a metal oxide film is obtained by heating a metal hydroxide film | membrane.

Regarding the action of the reducing agent used in the present invention, in the first metal oxide film forming step of the present invention, cerium nitrate (Ce (NO ₃ ) ₃ ) as a metal source and borane-dimethylamine complex (also known as: A case where a cerium oxide (CeO ₂ ) film is formed using dimethylamine borane (DMAB) and water as a solvent will be described.
The cerium oxide film is not yet clear, but is considered to be formed by the following six equations.
(I) Ce (NO ₃ ) ₃ → Ce ³⁺ + 3NO ₃ ⁻
(Ii) (CH ₃ ) ₂ NHBH ₃ + 2H ₂ O → BO ₂ ⁻ + (CH ₃ ) ₂ NH + 7H ⁺ + 6e ⁻
(Iii) 2H ₂ O + 2e ⁻ → 2OH ⁻ + H ₂
(Iv) Ce ³⁺ → Ce ⁴⁺ + e ⁻
(V) Ce ⁴⁺ + 2OH ⁻ → Ce (OH) ₂ ²⁺
(Vi) Ce (OH) ₂ ²⁺ → CeO ₂ + H ₂

At this time, cerium nitrate becomes cerium ions in the aqueous solution (formula (i)), and then the reducing agent DMAB decomposes (formula (ii)) to release electrons. Thereafter, the emitted electrons induce water electrolysis (formula (iii)) to generate hydroxide ions and raise the pH of the metal oxide film forming solution. As a result, the cerium ion changes the valence (formula (iv)) and further reacts with the generated hydroxide ion (formula (v)) to produce Ce (OH) ₂ ²⁺ . Thereafter, Ce (OH) ₂ ^{2+ in the} vicinity of the substrate becomes CeO ₂ due to a local increase in pH (formula (vi)). Then, the cerium oxide film is formed by repeating the reactions of formulas (ii) to (vi).

As for the action of the oxidizing agent used in the present invention, cerium nitrate (Ce (NO ₃ ) ₃ ) is used as the metal source in the first metal oxide film forming step as in the case of the reducing agent, and the oxidizing agent is used. Description will be made using sodium chlorate (NaClO ₃ ) and water as a solvent to form a cerium oxide (CeO ₂ ) film.
Although the cerium oxide film is not yet clear, it is considered to be formed by the following three expressions.
(Vii) Ce (NO ₃ ) ₃ → Ce ³⁺ + 3NO ₃ ⁻
(Viii) 2Ce ³⁺ + ClO ₃ ⁻ → 2Ce ⁴⁺ + ClO ₂ ⁻
(Ix) Ce ⁴⁺ + 2H ₂ O → CeO ₂ + 4H ⁺

At this time, cerium nitrate becomes cerium ion in the aqueous solution (formula (vii)), and then chlorate ion (ClO ₃ ⁻ ) obtained by dissolving the oxidizing agent (NaClO ₃ ) changes the valence of cerium ion. (Formula (viii)), and the resulting Ce ⁴⁺ reacts with water to become CeO ₂ (formula (ix)). Then, the cerium oxide film is formed by repeating the reactions of formulas (viii) to (ix). In addition, Ce ⁴⁺ generated in the formula (viii) can exist only as CeO ₂ or Ce (OH) ₂ ^{2+ in} the Pourbaix diagram, and in the present invention, immediately after Ce ⁴⁺ is generated, it is immediately converted into CeO _2. It is thought that it precipitates.

In the present invention, even when an alcohol, an organic solvent, or the like is used as a solvent instead of water, a metal oxide film is formed by a reaction similar to the above reaction or a trace amount of water contained in the solvent. I think that.
Hereinafter, the method for producing a metal oxide film of the present invention will be described in detail, divided into a first metal oxide film forming step and a second metal oxide film forming step.

A. First metal oxide film forming step In the first metal oxide film forming step of the present invention, the first metal oxide film is formed by dissolving a metal salt or metal complex as a metal source and at least one of an oxidizing agent and a reducing agent. In this step, the first metal oxide film is formed on the substrate by bringing the solution for use into contact with the substrate.

  In this step, since the wet coating uses the first metal oxide film forming solution, for example, even when the substrate has a complicated structure part, the solution easily penetrates into the structure part. Therefore, the first metal oxide film can be obtained inside or on the surface of the structure part. Furthermore, it can be set as the environment where a 1st metal oxide film tends to produce with the oxidizing agent and / or reducing agent which are contained in the said solution for 1st metal oxide film formation. Hereinafter, the first metal oxide film forming solution and the like used in this step will be described in detail.

1. First Metal Oxide Film Forming Solution First, the first metal oxide film forming solution used in the method for producing a metal oxide film of the present invention will be described. The first metal oxide film forming solution used in the present invention contains at least an oxidizing agent and / or a reducing agent, a metal salt or metal complex as a metal source, and a solvent.

(1) Oxidizing agent The oxidizing agent used in the first metal oxide film forming solution of the present invention has a function of promoting oxidation of metal ions or the like formed by dissolving a metal source described later. By changing the valence of metal ions or the like, it is possible to create an environment in which the first metal oxide film is easily generated.
The concentration of the oxidant in the first metal oxide film forming solution used in the present invention is usually 0.001 to 1 mol / l, although it varies depending on the type of the oxidant.
Among these, 0.01 to 0.1 mol / l is preferable. This is because if the concentration is below the above range, the first metal oxide film may not be formed, and if the concentration is above the above range, there will be no significant difference in the obtained effect, which is not preferable in terms of cost.

  Such an oxidizing agent is not particularly limited as long as it can be dissolved in a solvent described later and accelerate the oxidation of the metal source. For example, hydrogen peroxide, sodium nitrite, potassium nitrite Sodium bromate, potassium bromate, silver oxide, dichromic acid, potassium permanganate and the like. Among them, hydrogen peroxide and sodium nitrite are preferably used.

(2) Reducing agent The reducing agent used in the first metal oxide film-forming solution of the present invention releases electrons by a decomposition reaction and generates hydroxide ions by water electrolysis. It has the function of raising the pH of the substance film forming solution. The pH of the solution for forming the first metal oxide film can be raised and guided to the metal oxide region or the metal hydroxide region in the Pourbaix diagram, thereby creating an environment where the first metal oxide film is likely to be generated. .

The concentration of the reducing agent in the first metal oxide film forming solution used in the present invention varies depending on the type of the reducing agent, but is usually 0.001 to 1 mol / l.
Among these, 0.01 to 0.1 mol / l is preferable. This is because if the concentration is below the above range, the first metal oxide film may not be formed, and if the concentration is above the above range, there will be no significant difference in the obtained effect, which is not preferable in terms of cost.

  Such a reducing agent is not particularly limited as long as it can be dissolved in a solvent described later and can release electrons by a decomposition reaction. For example, borane-tert-butylamine complex, borane- Examples thereof include borane complexes such as N, N diethylaniline complex, borane-dimethylamine complex, borane-trimethylamine complex, sodium cyanoborohydride, and sodium borohydride. Among them, borane complex is preferably used.

  In this step, the first metal oxide film can be formed even when a reducing agent and the above-described oxidizing agent are used in combination. Such a combination of a reducing agent and an oxidizing agent is not particularly limited. For example, a combination of hydrogen peroxide or sodium nitrite and an arbitrary reducing agent, or an arbitrary oxidizing agent and a borane complex. The combination etc. are mentioned, Especially, the combination of hydrogen peroxide and a borane-type complex is preferable.

(3) Metal source The metal source used in the first metal oxide film-forming solution of the present invention is dissolved in the first metal oxide film-forming solution, and is first produced by the action of the oxidizing agent, reducing agent and the like described above. Any metal salt or metal complex may be used as long as it provides a metal oxide film. The “metal complex” in the present invention includes a metal ion coordinated with an inorganic substance or an organic substance, or a so-called organometallic compound having a metal-carbon bond in the molecule.
The concentration of the metal source in the first metal oxide film forming solution used in the present invention is usually 0.001 to 1 mol / l, particularly 0.01 to 0.1 mol when the metal source is a metal salt. When the metal source is a metal complex, it is usually 0.001 to 1 mol / l, and particularly preferably 0.01 to 0.1 mol / l. If the concentration is not more than the above range, the first metal oxide film may not be sufficiently formed and may not contribute to densification. If the concentration is not less than the above range, the metal oxide film has a uniform thickness. This is because there is a possibility that cannot be obtained.

  The metal element constituting such a metal source is not particularly limited as long as a desired first metal oxide film can be obtained. For example, Mg, Al, Si, Ca, Ti, V, Mn Fe, Co, Ni, Cu, Zn, Y, Zr, Ag, In, Sn, Ce, Sm, Pb, La, Hf, Sc, Gd, and Ta are preferably selected. Since the metal element has a metal oxide region or a metal hydroxide region in the Pourbaille diagram, it is suitable as a main constituent element of the first metal oxide film.

Specific examples of the metal salt that gives the metal element include chlorides, nitrates, sulfates, perchlorates, acetates, phosphates, bromates, and the like containing the metal elements. Among these, in the present invention, it is preferable to use chloride, nitrate, and acetate. This is because these compounds are easily available as general-purpose products.
Specific examples of the metal complex include magnesium diethoxide, aluminum acetylacetonate, calcium acetylacetonate dihydrate, calcium di (methoxyethoxide), calcium gluconate monohydrate, citric acid Calcium tetrahydrate, calcium salicylate dihydrate, titanium lactate, titanium acetylacetonate, tetraisopropyl titanate, tetranormal butyl titanate, tetra (2-ethylhexyl) titanate, butyl titanate dimer, titanium bis (ethylhexoxy) bis (2 -Ethyl-3-hydroxyhexoxide), diisopropoxytitanium bis (triethanolaminate), dihydroxybis (ammonium lactate) titanium, diisopropoxytitanium bis (ethylacetate) Toacetate), titanium peroxo ammonium citrate tetrahydrate, dicyclopentadienyl iron (II), iron lactate (II) trihydrate, iron (III) acetylacetonate, cobalt (II) acetylacetonate , Nickel (II) acetylacetonate dihydrate, copper (II) acetylacetonate, copper (II) dipivaloylmethanate, copper (II) ethylacetoacetate, zinc acetylacetonate, zinc lactate trihydrate , Zinc salicylate trihydrate, zinc stearate, strontium dipivaloylmethanate, yttrium dipivaloylmethanate, zirconium tetra-n-butoxide, zirconium (IV) ethoxide, zirconium normal propyrate, zirconium normal butyrate , Zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zir Nitroacetylacetonate bisethylacetoacetate, zirconium acetate, zirconium monostearate, penta-n-butoxyniobium, pentaethoxyniobium, pentaisopropoxyniobium, tris (acetylacetonato) indium (III), indium 2-ethylhexanoate (III), tetraethyltin, dibutyltin oxide (IV), tricyclohexyltin (IV) hydroxide, lanthanum acetylacetonate dihydrate, tri (methoxyethoxy) lanthanum, pentaisopropoxytantalum, pentaethoxytantalum, tantalum ( V) Ethoxide, cerium (III) acetylacetonate n-hydrate, lead (II) citrate trihydrate, lead cyclohexanebutyrate and the like. Among them, in the present invention, magnesium diethoxide, aluminum acetylacetonate, calcium acetylacetonate dihydrate, titanium lactate, titanium acetylacetonate, tetraisopropyl titanate, tetranormal butyl titanate, tetra (2-ethylhexyl) titanate , Butyl titanate dimer, diisopropoxy titanium bis (ethylacetoacetate), iron (II) lactate trihydrate, iron (III) acetylacetonate, zinc acetylacetonate, zinc lactate trihydrate, strontium dipivaloyl Methanate, pentaethoxyniobium, tris (acetylacetonato) indium (III), indium (III) 2-ethylhexanoate, tetraethyltin, dibutyltin oxide (IV), lanthanum acetylacetonate dihydrate , It is preferable to use tri (methoxyethoxy) lanthanum, cerium (III) acetylacetonate n-hydrate.
In the present invention, the first metal oxide film forming solution may contain two or more kinds of the above metal elements. By using a plurality of kinds of metal elements, for example, ITO, Gd—CeO ₂ , Sm—CeO ₂ , Ni—Fe ₂ O _{3 and} other composite first metal oxide films can be obtained.

(4) Solvent The solvent used in the first metal oxide film forming solution of the present invention is not particularly limited as long as it can dissolve the reducing agent and the metal source described above. In the case where the metal source is a metal salt, water, methanol, ethanol, isopropyl alcohol, propanol, butanol and other lower alcohols having a total carbon number of 5 or less, toluene, and mixed solvents thereof can be exemplified. When is a metal complex, the above-mentioned lower alcohol, toluene, and a mixed solvent thereof can be exemplified. In this step, the above solvents may be used in combination, for example, an organometallic complex that has low solubility in water but high solubility in organic solvent, and solubility in organic solvent is When using a reducing agent that is low but has high solubility in water, water and an organic solvent are mixed to dissolve both of them, and a uniform metal oxide film forming solution can be obtained.
(5) Additive The solution for forming the first metal oxide film used in the present invention may contain additives such as an auxiliary ion source and a surfactant.
The auxiliary ion source reacts with electrons to generate hydroxide ions, and raises the pH of the first metal oxide film forming solution so that the first metal oxide film can be easily formed. Can do. The amount of the auxiliary ion source used is preferably appropriately selected according to the metal source and the reducing agent to be used.

Specific examples of such auxiliary ion sources include chlorate ions, perchlorate ions, chlorite ions, hypochlorite ions, bromate ions, hypobromate ions, nitrate ions, and nitrite ions. An ionic species selected from the group consisting of These auxiliary ion sources are believed to cause the following reactions in solution.
^{_{ClO 4 - + H 2 O +}} 2e - ⇔ ClO 3 - + 2OH -
^{_{ClO 3 - + H 2 O +}} 2e - ⇔ ClO 2 - + 2OH -
^{_{ClO 2 - + H 2 O +}} 2e - ⇔ ClO - + 2OH -
_{^{2ClO - + 2H 2 O + 2e}} - ⇔ Cl 2 (g) + 4OH -
^{_{BrO 3 - + 2H 2 O +}} 4e - ⇔ BrO - + 4OH -
_{^{2BrO - + 2H 2 O + 2e}} - ⇔ Br 2 + 4OH -
^{_{NO 3 - + H 2 O +}} 2e - ⇔ NO 2 - + 2OH -
NO ₂ ⁻ + 3H ₂ O + 3e ⁻ ＮＨ NH ₃ + 3OH ⁻

The surfactant acts on the interface between the first metal oxide film forming solution and the substrate surface, and has a function of facilitating the formation of a metal oxide film on the substrate surface. The amount of the surfactant used is preferably selected and used in accordance with the metal source and reducing agent used.
Such surfactants are specifically Surfinol 485, Surfinol SE, Surfinol SE-F, Surfinol 504, Surfinol GA, Surfinol 104A, Surfinol 104BC, Surfinol 104PPM, Surfinol 104E, Surfynol series such as Surfinol 104PA (all manufactured by Nissin Chemical Industry Co., Ltd.), NIKKOL AM301, NIKKOL AM313ON (all manufactured by Nikko Chemical Co., Ltd.) and the like can be mentioned.

2. First Metal Oxide Film Next, the first metal oxide film formed in this step will be described. In the present invention, the first metal oxide film is formed by bringing the first metal oxide film forming solution and the substrate into contact with each other.
The first metal oxide film supported on the substrate is not particularly limited as long as a metal oxide film having a desired denseness can be obtained by a second metal oxide film forming step described later. For example, the base material may be completely covered to form a metal oxide film, or the base material may be partially covered. As the first metal oxide film partially covering the base material, for example, when it exists in the shape of a sea island inside the porous base material, it exists in a pattern on the smooth base material surface. And the like.
The first metal oxide film preferably has a crystal system close to that of the metal oxide constituting the second metal oxide film, and is a metal oxide film containing a main element constituting the second metal oxide film. More preferably.

3. Next, the base material used in the method for producing a metal oxide film of the present invention will be described. The material of the substrate used in the present invention is not particularly limited as long as it has heat resistance with respect to the heating temperature in the second metal oxide film forming step described later. For example, glass, SUS , Metal plates, ceramic substrates, heat-resistant plastics, etc., among which glass, SUS, metal plates, ceramic substrates are preferably used. This is because it is versatile and has sufficient heat resistance.
The substrate used in the present invention is not particularly limited. For example, a substrate having a smooth surface, a microstructure, a hole, or a groove is engraved. In the present invention, it is preferable that the base material has a structural part, for example, the base material has a complicated fine structure, and is porous. The substrate is preferably a substrate or a substrate provided with a porous film. The first metal oxide film forming solution penetrates into the inside of the base material to form the first metal oxide film, and has a good shape following property through the second metal oxide film forming process described later. This is because a dense metal oxide film having the above can be obtained.

4). Next, a contact method between the base material and the first metal oxide film forming solution in this step will be described. The contact method in this step is not particularly limited as long as it is a method in which the above-described substrate and the above-described first metal oxide film forming solution are brought into contact with each other. , A dipping method, a single-wafer method, a method of applying the solution in the form of a mist, and the like.
For example, the roll coating method is a method of forming a first metal oxide film on the base material 1 by passing the base material 1 between a roll 7 and a roll 8 as shown in FIG. Suitable for continuous metal oxide film production. The dipping method is a method of forming the first metal oxide film on the base material by immersing the base material in the first metal oxide film forming solution. For example, as shown in FIG. As described above, the first metal oxide film is formed on the entire surface of the base material 1 by immersing the entire base material 1 in the first metal oxide film forming solution 2. Although not shown in FIG. 4A, a patterned first metal oxide film can be provided on the surface of the substrate 1 by providing a shielding portion on the surface of the substrate 1. For example, as shown in FIG. 4B, the first metal oxide film forming solution 2 is allowed to flow at a constant flow rate, and the first metal oxide film forming solution 2 is applied only to the inner peripheral surface of the substrate 1. By contacting, the first metal oxide film can be provided only on the inner peripheral surface. In addition, as shown in FIG. 5, for example, the single-wafer method circulates the first metal oxide film forming solution 2 with a pump 9 and heats only the base material 1, so that This is a method for promoting a reaction for forming a single metal oxide film and forming a first metal oxide film on a substrate.

  Further, in this step, when the above-described base material and the above-described first metal oxide film forming solution are brought into contact with each other, an oxidizing gas is mixed, irradiated with ultraviolet rays, heated, or these By combining these, the production speed of the first metal oxide film can be improved. Hereinafter, these methods will be described.

(1) Improvement of production rate by mixing of oxidizing gas In this step, it is preferable to mix oxidizing gas when the substrate and the first metal oxide film forming solution are brought into contact with each other.
Such an oxidizing gas is not particularly limited as long as it is a gas having an oxidizing ability and can improve the production rate of the first metal oxide film. For example, oxygen, Examples thereof include ozone, nitrous acid gas, nitrogen dioxide, nitrogen dioxide, chlorine dioxide, and halogen gas. Among them, oxygen and ozone are preferably used, and ozone is particularly preferably used. This is because it is easy to obtain industrially and can reduce the cost.

  Further, the mixing method of the oxidizing gas is not particularly limited. For example, when the above-described immersion method is used, the base material and the first metal oxide film forming solution are in contact with each other. For example, a method in which the bubble-like oxidizing gas is brought into contact with the portion that is present. The introduction of such a bubble-like oxidizing gas is not particularly limited, and examples thereof include a method using a bubbler. By using a bubbler, the contact area between the oxidizing gas and the solution can be increased, and the production rate of the first metal oxide film can be improved efficiently. As such a bubbler, a general bubbler can be used, and examples thereof include a Naflon bubbler (manufactured by ASONE). In addition, the oxidizing gas can be normally supplied from a gas cylinder, and ozone can be supplied from the ozone generator to the first metal oxide film forming solution.

(2) Improvement of production rate by irradiation with ultraviolet rays Further, in this step, it is preferable to irradiate ultraviolet rays when the substrate and the first metal oxide film forming solution are brought into contact with each other. By irradiating ultraviolet rays, it is considered that the reaction corresponding to the electrolysis of water can be induced and the decomposition of the reducing agent can be promoted. The generated hydroxide ions form the first metal oxide film. This is because the pH of the working solution can be raised, and an environment in which the first metal oxide film can be easily formed can be obtained. Furthermore, the crystallinity of the obtained first metal oxide film can be improved by irradiating with ultraviolet rays.

The ultraviolet irradiation method in this step is not particularly limited as long as it is a method of irradiating the contact portion between the substrate and the first metal oxide film forming solution. For example, the above-described immersion method is used. In such a case, as shown in FIG. 6, a method of immersing the base material 1 in the first metal oxide film forming solution 2 and irradiating ultraviolet rays 10 from the solution side can be used. In this case, from the viewpoint of accurately irradiating the contact portion between the base material and the metal first oxide film forming solution with ultraviolet rays, the metal oxide film forming surface existing on the substrate surface irradiated with the ultraviolet rays is used. The solution is preferably thin.
Moreover, as a wavelength of the said ultraviolet-ray, it is 185-470 nm normally, and it is preferable that it is 185-260 nm especially. Moreover, as an intensity | strength of the ultraviolet-ray used for this aspect, it is 1-20 mW / cm < ² > normally, and it is preferable that it is 5-15 mW / cm < ² > especially.
As an ultraviolet irradiation apparatus that performs such ultraviolet irradiation, a commercially available UV light irradiation apparatus, laser oscillation apparatus, or the like can be used, and examples thereof include HB400X-21 manufactured by SEN Special Light Source Co., Ltd. Can do.

(3) Improvement of production rate by heating Moreover, in this process, it is preferable to perform heating when the substrate and the first metal oxide film forming solution are brought into contact with each other. This is because the production rate of the first metal oxide film can be improved by heating. The method for heating is not particularly limited as long as it is a method capable of improving the production rate of the first metal oxide film. It is preferable to heat the monometallic oxide film forming solution. This is because the formation reaction of the first metal oxide film in the vicinity of the substrate can be promoted.
Such a heating temperature is preferably appropriately selected according to the characteristics of the first metal oxide film forming solution to be used, etc., but specifically, preferably within a range of 50 to 150 ° C., Especially, it is more preferable that it exists in the range of 70-100 degreeC.

B. Second metal oxide film forming step In the second metal oxide film forming step of the present invention, the substrate provided with the first metal oxide film is heated to a temperature equal to or higher than the metal oxide film forming temperature, The second metal oxide film is obtained by contacting with a solution for forming a second metal oxide film in which a metal salt or metal complex is dissolved. In the present invention, “metal oxide film forming temperature” means that the metal element constituting the metal source contained in the second metal oxide film forming solution is combined with oxygen, and the metal oxide film is formed on the substrate. The temperature at which can be formed is greatly different depending on the type of metal source such as a metal salt or metal complex and the composition of the second metal oxide film forming solution such as a solvent. In the present invention, such “metal oxide film formation temperature” can be measured by the following method. That is, by preparing a solution for forming a second metal oxide film that actually contains a desired metal source, and changing the heating temperature of the base material, it is possible to form a metal oxide film. The substrate heating temperature is measured. This minimum substrate heating temperature can be set as the “metal oxide film forming temperature” in the present invention. At this time, whether or not the metal oxide film is formed is determined from the result obtained from the X-ray diffraction apparatus (Rigaku, RINT-1500). In the case of an amorphous film having no crystallinity, a photoelectron spectrometer is used. It shall be judged from the result obtained from (V. G. Scientific, ESCALAB 200i-XL).

In this step, the first metal oxide film is heated to a temperature equal to or higher than the metal oxide film formation temperature, and the second metal oxide film forming solution is brought into contact with the first metal oxide film. A second metal oxide film can be provided on the oxide film, and as a result, a metal oxide film having a uniform, dense, and sufficient film thickness can be obtained.
Hereinafter, this process is demonstrated in detail for every structure.

1. Second Metal Oxide Film Forming Solution First, the second metal oxide film forming solution used in the method for producing a metal oxide film of the present invention will be described. The solution for forming a second metal oxide film used in the present invention contains at least a metal salt or metal complex as a metal source and a solvent.
Moreover, in this invention, it is preferable that the said solution for 2nd metal oxide film formation contains at least one of an oxidizing agent and a reducing agent. This is because by containing at least one of an oxidizing agent and a reducing agent, the second metal oxide film can be obtained at a lower substrate heating temperature as compared with the conventional spray pyrolysis method. Hereinafter, the configuration of the second metal oxide film forming solution will be described.

(1) Metal source The metal source used in the second metal oxide film-forming solution of the present invention is dissolved in the second metal oxide film-forming solution and on the substrate provided with the first metal oxide film. A second metal oxide film is provided. As long as the said metal source melt | dissolves in the solvent mentioned later, a metal salt may be sufficient and a metal complex may be sufficient.
The concentration of the metal source in the second metal oxide film forming solution used in the present invention is usually 0.001 to 1 mol / l, particularly 0.01 to 0.5 mol when the metal source is a metal salt. When the metal source is a metal complex, it is usually 0.001 to 1 mol / l, and particularly preferably 0.01 to 0.5 mol / l. If the concentration is below the above range, it may take time to form the second metal oxide film on the substrate, which may not be industrially suitable. This is because a bimetallic oxide film may not be obtained.

  The metal element constituting such a metal source is not particularly limited as long as a desired second metal oxide film can be obtained. For example, Mg, Al, Si, Ca, Ti, V, Mn Fe, Co, Ni, Cu, Zn, Y, Zr, Ag, In, Sn, Ce, Sm, Pb, La, Hf, Sc, Gd, Ta, Cr, Ga, Sr, Nb, Mo, Pd, Sb , Te, Ba, and W are preferably selected. Since the metal element can produce a stable metal oxide, it is suitable as a main constituent element of the second metal oxide film.

Specific examples of the metal salt that gives the metal element include chlorides, nitrates, sulfates, perchlorates, acetates, phosphates, bromates, and the like containing the metal elements. Among these, in the present invention, it is preferable to use chloride, nitrate, and acetate. This is because these compounds are easily available as general-purpose products.
Specific examples of the metal complex include the metal complexes mentioned in the above-mentioned first metal oxide film forming solution, and further include calcium acetylacetonate dihydrate, chromium (III ) Acetylacetonate, gallium (III) trifluoromethanesulfonate, strontium dipivaloylmethanate, niobium pentachloride, molybdenylacetylacetonate, palladium (II) acetylacetonate, antimony (III) chloride, sodium tellurate, Examples thereof include barium chloride dihydrate and tungsten chloride (VI).

In the present invention, the second metal oxide film forming solution may contain two or more of the above metal elements. By using a plurality of kinds of metal elements, for example, ITO, Gd—CeO ₂ , Sm—CeO ₂ , Ni—Fe ₂ O _{3 and} other composite metal oxide films can be obtained.

(2) Oxidizing agent The oxidizing agent used in the second metal oxide film forming solution of the present invention has a function of promoting oxidation of metal ions or the like formed by dissolving a metal source described later. By changing the valence of metal ions, etc., it is possible to create an environment in which the second metal oxide is likely to be generated, and the second metal oxide film can be formed at a lower substrate heating temperature compared to the conventional spray pyrolysis method. Can be obtained.
The concentration of the oxidizing agent in the second metal oxide film forming solution used in the present invention is usually 0.001 to 1 mol / l, although it varies depending on the type of the oxidizing agent.
Among these, 0.01 to 0.1 mol / l is preferable. If the concentration is below the above range, the effect of lowering the substrate heating temperature may not be sufficiently exhibited. If the concentration is above the above range, there will be no significant difference in the obtained effect, and the cost This is because it is not preferable. Moreover, since the specific example of such an oxidizing agent is the same as what was described in "A. 1st metal oxide film formation process", description here is abbreviate | omitted.

(3) Reducing agent The reducing agent used in the solution for forming a second metal oxide film of the present invention releases electrons by a decomposition reaction and generates hydroxide ions by electrolysis of water. It has the function of raising the pH of the substance film forming solution. When the pH of the second metal oxide film forming solution is increased, the solution can be guided to a metal oxide region or a metal hydroxide region in the Pourbaix diagram, and an environment in which a metal oxide film is easily generated can be obtained. Compared to the conventional spray pyrolysis method, the second metal oxide film can be obtained at a lower substrate heating temperature.

The concentration of the reducing agent in the second metal oxide film forming solution used in the present invention varies depending on the type of the reducing agent, but is usually 0.001 to 1 mol / l.
Among these, 0.01 to 0.1 mol / l is preferable. If the concentration is below the above range, the effect of lowering the substrate heating temperature may not be sufficiently exhibited. If the concentration is above the above range, there will be no significant difference in the obtained effect, and the cost This is because it is not preferable. Moreover, since the specific example of such a reducing agent is the same as what was described in "A. 1st metal oxide film formation process", description here is abbreviate | omitted.

  In the present invention, the second metal oxide film can be obtained at a lower substrate heating temperature as compared with the conventional spray pyrolysis method even when the reducing agent and the oxidizing agent described above are used in combination. . Such a combination of a reducing agent and an oxidizing agent is not particularly limited as long as it is a combination capable of lowering the substrate heating temperature. For example, hydrogen peroxide or sodium nitrite and any reducing agent can be used. And a combination of an arbitrary oxidizing agent and a borane complex. Among them, a combination of hydrogen peroxide and a borane complex is preferable.

(4) Solvent The solvent used in the solution for forming the second metal oxide film of the present invention is not particularly limited as long as it can dissolve the above-described metal source and the like. Specific examples of the solvent are the same as those described in “A. First Metal Oxide Film Forming Step”, and thus description thereof is omitted here.

(5) Additive The solution for forming a second metal oxide film used in the present invention may contain additives such as ceramic fine particles, an auxiliary ion source, and a surfactant.

When the ceramic fine particles are contained in the second metal oxide film forming solution, a second metal oxide film is formed so as to surround the ceramic fine particles, and a mixed film of different ceramics can be obtained. The volume of the film can be increased. Moreover, it is preferable that the content of the ceramic fine particles is appropriately selected according to the characteristics of the member to be used.
Such ceramic fine particles are not particularly limited as long as the above object can be achieved. For example, ITO, aluminum oxide, zirconium oxide, silicon oxide, titanium oxide, tin oxide , Cerium oxide, calcium oxide, manganese oxide, magnesium oxide, barium titanate and the like.
The auxiliary ion source and the surfactant are the same as those described in “A. First metal oxide film forming step”, and thus description thereof is omitted here.

2. Second Metal Oxide Film Next, the metal oxide film in the present invention will be described. The metal oxide film in the present invention is heated to the second metal oxide film forming solution and the metal oxide film forming temperature in the second metal oxide film forming step, which is the present step. It can be obtained by contacting a substrate provided with a film. By providing the second metal oxide film on the first metal oxide film, a metal oxide film having a uniform, dense and sufficient film thickness can be obtained.
In the present invention, the combination of the first metal oxide film and the second metal oxide film is not particularly limited as long as a metal oxide film having a desired density can be obtained. A combination in which the crystal systems of metal oxides are close to each other is preferable, and a combination in which metal elements constituting the metal oxide film are common is more preferable.
For example, when the second metal oxide film is an ITO film, the first metal oxide film is particularly limited as long as a dense ITO film can be formed as the second metal oxide film. but not, for _{example, ZnO, ZrO 2, Al 2} O 3, Y 2 O 3, Fe 2 O 3, Ga 2 O 3, La 2 O 3, Sb 2 O 3, ITO, in 2 O 3, SnO 2 Among them, Al ₂ O ₃ , Y ₂ O ₃ , Fe ₂ O ₃ , Ga ₂ O ₃ , La ₂ O ₃ from the viewpoint that the crystal system is close to the metal oxide film (ITO film). , Sb ₂ O ₃ , ITO, In ₂ O ₃ , SnO ₂ , and in particular, from the viewpoint that the metal elements (In, Sn) constituting the metal oxide film (ITO film) are common, ITO, It is in ₂ O _3, SnO ₂ Theft is more preferable.

3. Method of contacting base material provided with first metal oxide film and second metal oxide film forming solution Next, base material provided with first metal oxide film and second metal oxide film formation in this step The contact method with the solution for preparation will be described. The contact method in this step is not particularly limited as long as it is a method in which the above-described base material and the above-described second metal oxide film forming solution are brought into contact with each other. It is preferable that the temperature of the base material is not lowered when the solution for use and the base material are in contact with each other. This is because when the temperature of the substrate is lowered, the film formation reaction does not occur and a desired second metal oxide film may not be obtained. Examples of a method for not lowering the temperature of the base material include a method of bringing the second metal oxide film forming solution into contact with the base material as a droplet, and the diameter of the droplet is particularly small. Is preferred. If the droplet diameter is small, the solvent of the solution for forming the second metal oxide film is instantly evaporated, and the decrease in the substrate temperature can be further suppressed. This is because a simple metal oxide film can be obtained.
The method for bringing the droplets of the metal oxide film forming solution having such a small diameter into contact with the substrate is not particularly limited, but specifically, the second metal oxide film forming solution is used. Examples thereof include a method of bringing the substrate into contact with the substrate by spraying, a method of allowing the substrate to pass through a space in which the solution for forming the second metal oxide film is made into a mist.

Examples of the method of bringing the second metal oxide forming solution into contact with the substrate by spraying include a method of spraying using a spray device or the like. When spraying using the above spray apparatus or the like, the diameter of the droplets is usually 0.001 to 1000 μm, preferably 0.01 to 300 μm, and particularly preferably 0.01 to 100 μm. This is because if the droplet diameter is within the above range, the substrate temperature can be prevented from lowering, and a uniform second metal oxide film can be obtained.
Further, the spray gas of the spray device is not particularly limited as long as it does not inhibit the formation of the second metal oxide film, and examples thereof include air, nitrogen, argon, helium, oxygen, and the like. Among these, inert gases such as nitrogen, argon, and helium are preferably used. In addition, the injection amount of the injection gas is preferably 0.1 to 50 l / min, and more preferably 1 to 20 l / min. The spray device may be a fixed device, a movable device, a device that ejects the solution by rotation, a device that ejects only the solution by pressure, or the like. As such a spray device, a commonly used spray device can be used, for example, hand spray (spray gun No. 8012, manufactured by ASONE), ultrasonic nepriser (NE-U17, manufactured by OMRON), etc. Can be used.

  Moreover, in the method of allowing the substrate to pass through the space in which the second metal oxide film forming solution is made into a mist, the diameter of the droplets is usually 0.1 to 300 μm, particularly 1 to 100 μm. preferable. This is because if the droplet diameter is within the above range, the substrate temperature can be prevented from lowering, and a uniform second metal oxide film can be obtained.

In the present invention, the second metal oxide film forming solution and the heated base material are brought into contact with each other. At this time, the base material is heated to a temperature equal to or higher than the above-mentioned “metal oxide film forming temperature”. Is done. Such “metal oxide film formation temperature” depends on the type of the metal source, the composition of the second metal oxide film forming solution such as the solvent, etc., but is oxidized into the upper first electrode layer forming coating liquid. When an agent and / or a reducing agent are not added, the temperature can usually be in the range of 400 to 1000 ° C, and in particular, it is preferably in the range of 450 to 700 ° C. On the other hand, when an oxidizing agent and / or a reducing agent is added to the upper first electrode layer forming coating solution, it can usually be in the range of 150 to 400 ° C, and in particular, in the range of 200 to 400 ° C. Is preferred.
In addition, the heating method for the base material is not particularly limited, and examples thereof include a heating method such as a hot plate, an oven, a firing furnace, an infrared lamp, a hot air blower, etc. A method in which the second metal oxide film forming solution can be contacted while maintaining the temperature at the above temperature is preferable, and specifically, a hot plate or the like is preferably used.

Next, the contact method between the substrate and the second metal oxide film forming solution in the present invention will be specifically described. Examples of the method for bringing the substrate into contact with the substrate by spraying the second metal oxide forming solution described above include, for example, a method of continuously moving and spraying the substrate with a roller, and a method of spraying on a fixed substrate. And a method of spraying on a flow path such as a pipe.
For example, as shown in FIG. 7, the base material 1 provided with the first metal oxide film is heated to a temperature equal to or higher than the metal oxide film formation temperature. In this method, the metal oxide film is formed by spraying the solution 4 for forming the second metal oxide film with the spray device 5 and continuously moving the film using the rollers 11 to 13. This method has an advantage that a metal oxide film can be continuously formed.
Moreover, the method of spraying on the fixed base material is, for example, as shown in FIG. 1C, the base material 1 provided with the first metal oxide film 3 at a temperature equal to or higher than the metal oxide film formation temperature. The substrate 1 is sprayed with the spray device 5 to spray the second metal oxide film forming solution 4 to form a second metal oxide film. As a result, a dense metal oxide is formed. This is a method for obtaining a material film.

  In addition, for example, as shown in FIG. 8, the second metal oxide film forming solution 4 is prepared by passing the substrate through a space in which the second metal oxide film forming solution is made into a mist. In the mist-like space, the metal oxide film is heated to a temperature equal to or higher than the metal oxide film formation temperature, and the second metal oxide film is formed by passing the substrate 1 provided with the first metal oxide film. This is a method of forming an oxide film.

C. In addition, in the method for producing a metal oxide film of the present invention, the metal oxide film obtained by the above-described contact method or the like may be washed. The cleaning of the metal oxide film is performed to remove impurities present on the surface of the metal oxide film, for example, a method of cleaning using a solvent used in the metal oxide film forming solution. Etc.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be specifically described with reference to examples.

[Example 1]
<Zirconium oxide film formation on SUS base material subjected to microfabrication>
In this example, an experiment for imparting insulating properties was performed by forming a zirconium oxide film on a SUS base material subjected to microfabrication.
First, in this example, SUS304 (1 mm thickness) that was finely processed (groove: width 100 μm, length 10 mm, depth 50 μm) by an etching method was used as a base material.
Next, 5 g of borane-trimethylamine complex (manufactured by Kanto Chemical Co., Inc.) as a reducing agent is added to 1000 g of 0.05 mol / l aqueous solution of zirconium nitrate dihydrate (manufactured by Kanto Chemical Co., Ltd.), and the first metal oxide A film forming solution was obtained.
Next, the first metal oxide film forming solution was heated to a temperature of 80 ° C., and air bubbles were generated using a Naflon bubbler (manufactured by ASONE) at a constant temperature of 80 ° C. At this time, the first metal oxide film forming solution was circulated and passed through a filter to eliminate precipitates and contaminated dust.
Next, the substrate was ultrasonically washed with a neutral detergent and further immersed in a 30% aqueous solution of nitric acid and hydrochloric acid (equal amount) for 3 minutes, and 1% was added to the first metal oxide film forming solution. It was immersed for a time to obtain a first metal oxide film on the substrate.
The first metal oxide film obtained by the above method was visually confirmed after washing with pure water. As a result, a film having an interference color observed on both sides of the substrate and the finely processed portion was confirmed.
Next, 10 g of hydrogen peroxide as an oxidizing agent was added to 1000 g of a 0.1 mol / l aqueous solution of zirconium (IV) chloride (manufactured by Kanto Chemical Co., Ltd.) to obtain a second metal oxide film forming solution.
Next, the base material provided with the first metal oxide film is heated to 400 ° C. with a hot plate (manufactured by ASONE), and the second metal oxide film forming solution is hand sprayed (spray gun) onto the base material. No. 8012 (manufactured by AS ONE) was sprayed to form a second metal oxide film, and a metal oxide film was obtained on the substrate.
When the metal oxide film obtained by the above method was measured using an X-ray diffraction apparatus (Rigaku, RINT-1500), it was found to be an amorphous film. Therefore, when the composition of the metal oxide film was analyzed by a photoelectron spectroscopic analyzer (manufactured by V. G. Scientific, ESCALAB 200i-XL), Zr was 32.8 Atomic%, O was 68.1 Aotic%, and oxidation was performed. It was confirmed that a zirconium film was formed. Furthermore, when the surface resistance of the metal oxide film formed on the base material was measured using Loresta (manufactured by Mitsubishi Chemical Corporation), insulation could be confirmed.

[Example 2]
<Zinc oxide film formation on finely processed copper substrate>
In this example, an experiment was performed in which corrosion resistance was imparted while maintaining conductivity by forming a zinc oxide film on a finely processed copper base material.
First, in this example, copper (1 mm thickness) that was finely processed (groove: width 50 μm, length 10 mm, depth 20 μm) by an etching method was used as a base material.
Next, to 1000 g of a 0.05 mol / l ethanol solution of zinc acetate (manufactured by Kanto Chemical Co., Ltd.), a borane-dimethylamine complex (manufactured by Kanto Chemical Co., Ltd.) as a reducing agent was added so as to be 0.08 mol / l, Furthermore, 1 g of potassium nitrite (manufactured by Kanto Chemical Co., Inc.) was added as an auxiliary ion source to obtain a first metal oxide film forming solution.
Next, the first metal oxide film forming solution was heated to a temperature of 70 ° C., and air bubbles were generated using a Naflon bubbler (manufactured by ASONE) at a constant temperature of 70 ° C. At this time, the first metal oxide film forming solution was circulated and passed through a filter to eliminate precipitates and contaminated dust.
Next, the base material ultrasonically cleaned with a neutral detergent is placed on a hot plate heated to 90 ° C., and the solution for forming the first metal oxide film in which bubbles are generated by a bubbler is placed on the base material. Then, the state of circulating again was performed for one hour on each side. Then, when it wash | cleaned with a pure water, the film | membrane of the grade which can observe an interference color on both surfaces of a base material and a fine process part was confirmed.
Next, 10 g of a surfactant (manufactured by Nissin Chemical Industry Co., Ltd., Surfynol 485) is added to 1000 g of a zinc nitrate 0.1 mol / l aqueous solution, and a borane-tert-butylamine complex (manufactured by Kanto Chemical Co., Ltd.) which is a reducing agent. ) Was added to obtain a second metal oxide film forming solution.
Next, the base material provided with the first metal oxide film is heated to 350 ° C. with a hot plate (manufactured by ASONE), and the second metal oxide film forming solution is hand sprayed (spray gun) onto the base material. No. 8012 (manufactured by AS ONE) was sprayed to form a second metal oxide film, and a metal oxide film was obtained on the substrate.
When the metal oxide film obtained by the above method was measured using an X-ray diffractometer (RINT-1500, manufactured by Rigaku), it was confirmed that a zinc oxide film was formed. Furthermore, when the surface resistance of the zinc oxide film formed on the substrate was measured using Loresta (manufactured by Mitsubishi Chemical Corporation), the surface resistance was 100Ω / □, and the conductivity could be confirmed. Moreover, although the base material provided with the said zinc oxide film | membrane was immersed in the iodine (Wako Purechemical) solution for 24 hours, the change was not looked at by the base material and sufficient corrosion resistance was shown. In addition, when it immersed in the iodine (Wako Purechemical) solution for 24 hours similarly with respect to the copper base material which is not provided with the metal oxide film, the porous corrosion was seen.

[Comparative Example 1]
<ITO film formation on a copper substrate finely processed by dip coating>
In this comparative example, the finely processed copper (groove: width 50 μm, length 10 mm, depth 20 μm) used in Example 2 was used as the base material.
Next, a 10% ethanol solution of ITO fine particles (manufactured by Hosokawa Micron) is prepared, applied to the substrate by dip coating, and baked at a temperature of 500 ° C. for 2 hours in an electric muffle furnace (Denken, P90). As a result, an ITO film was obtained on the substrate.
When the ITO film obtained by the above method was immersed in an iodine (Wako Pure Chemicals) solution for 24 hours, pitting corrosion was confirmed as in the case of the untreated substrate, and sufficient corrosion resistance was not exhibited. Furthermore, when surface resistance was measured using Loresta (Mitsubishi Chemical Corporation), it was found to be 10000Ω / □ and poor in conductivity.

[Example 3]
<Formation of ITO transparent electrode film on porous substrate>
In this example, an experiment was performed to give a uniform and dense ITO transparent electrode film to a glass substrate with a porous titanium oxide film.
First, in water and isopropyl alcohol as solvents, titanium oxide fine particles having a primary particle size of 20 nm (P25, manufactured by Nippon Aerosil Co., Ltd.) 37.5% by weight, acetylacetone 1.25% by weight, polyethylene glycol (average molecular weight 3000) 1.88% by weight %, And a homogenizer was used to prepare a slurry in which the sample was dissolved and dispersed. This slurry was applied on a glass substrate by the doctor blade method, left for 20 minutes, and dried at 100 ° C. for 30 minutes. Then, it baked in an atmospheric pressure atmosphere for 30 minutes at 500 degreeC using the electric muffle furnace (made by Denken, P90). Thereby, a glass substrate with a porous titanium oxide film was obtained.
Next, a borane-trimethylamine complex as a reducing agent (manufactured by Kanto Chemical Co., Inc.) was added to 1000 g of an aqueous solution of 0.03 mol / l indium chloride and 0.001 mol / l tin chloride so as to be 0.05 mol / l. Further, 2 g of nitric acid 1.42 (manufactured by Kanto Chemical Co., Inc., 70% aqueous solution of nitric acid) as a nitrate ion source was added to obtain a first metal oxide film forming solution.
Next, the glass substrate with the porous titanium oxide film was immersed in the solution at a temperature of 80 ° C. for 2 minutes to obtain a first metal oxide film on the substrate. At this time, it was visually confirmed that the white color of titanium oxide turned yellow.
Next, 1000 g of ethanol-water mixed solution of 0.1 mol / l indium chloride and 0.05 mol / l tin chloride (ethanol: water = 1: 1), 2 g of sodium bromate as an auxiliary ion source, and oxidation Hydrogen peroxide solution 10 g as an agent was added to obtain a second metal oxide film forming solution.
Next, the base material provided with the first metal oxide film is heated to 300 ° C. with a hot plate (manufactured by ASONE), and the second metal oxide film forming solution is hand sprayed (spray gun) onto the base material. No. 8012 (manufactured by AS ONE) was sprayed to form a second metal oxide film, and a metal oxide film was obtained on the substrate. When the obtained metal oxide film was visually confirmed after washing with pure water, the luster that was thought to be due to the formation of a dense metal oxide film was confirmed.
When the metal oxide film obtained by the above method was measured using an X-ray diffractometer (Rigaku, RINT-1500), it was confirmed that an ITO film was formed. Furthermore, when the surface resistance of the ITO film provided on the porous titanium oxide film of the base material was measured using Loresta (manufactured by Mitsubishi Chemical Corporation), it was 0.4Ω / □. When a similar ITO film was provided only on a glass substrate that does not have a porous titanium oxide film, the surface resistance was 0.4Ω / □, and the total light transmittance on the glass surface was 86%. It was.

[Comparative Example 2]
Using the same glass substrate with a porous titanium oxide film as in Example 3, an ITO transparent conductive film was applied to the porous substrate by a sputtering method. The film formation was performed at an applied power of 1.0 kW and an oxygen gas flow rate of 90 sccm for 5 minutes. As a result, the porous titanium oxide film was peeled off from the glass substrate. This is thought to be due to the high stress of the film formed by sputtering.

[Comparative Example 3]
Using the same glass substrate with a porous titanium oxide film as in Example 3, an ITO transparent conductive film was applied to the porous substrate by a printing method. A 10% ethanol solution of ITO fine particles (manufactured by Hosokawa Micron Corporation) was applied to the titanium oxide surface of the glass substrate with the porous titanium oxide film with a Meyer bar (No. 16), and then 10% at room temperature. It was allowed to stand for 1 minute and then dried at 100 ° C. for 30 minutes. Subsequently, firing was performed in an atmospheric atmosphere at 350 ° C. for 30 minutes using an electric muffle furnace (P90, manufactured by Denken).
When the surface resistance of the titanium oxide surface of the glass substrate with the porous titanium oxide film thus obtained was measured with Loresta (Mitsubishi Chemical Corporation), a resistance of 5000Ω / □ was obtained, but it was not dense. Therefore resistance was high. Moreover, when observed with a scanning electron microscope (Hitachi, S-4500), it was a porous ITO film.

[Example 4]
In this embodiment, glass was used as the substrate, and a titanium oxide film was formed on the glass. First, titanium chloride (TiCl ₄ ) was dissolved as a metal source in a mixed solvent of 80 vol% water and 20 vol% isopropyl alcohol (IPA) to prepare 1000 g of a solution having a concentration of 0.06 mol / l. Thereafter, a borane-dimethylamine complex (manufactured by Kanto Chemical Co., Inc.), which is a reducing agent, was added to the above solution so as to be 0.1 mol / l to obtain a first metal oxide film forming solution.
Next, the first metal oxide film was obtained on the base material by immersing the base metal in the first metal oxide film forming solution at a constant temperature of 90 ° C. for 12 hours.
Next, titanium acetylacetonate ((C ₃ H ₇ O) ₂ Ti (C ₅ H ₇ O ₂ ) ₂ ) as a metal source was added to 1000 g of a mixed solvent of 10 vol% water, 80 vol% IPA, and 10 vol% toluene. The solution was dissolved to 1 mol / l to obtain a second metal oxide film forming solution.
Next, the base material provided with the first metal oxide film is heated to 380 ° C. with a hot plate (manufactured by ASONE), and the second metal oxide film forming solution is hand sprayed (spray gun) onto the base material. No. 8012 (manufactured by ASONE) was sprayed for 3 minutes to form a second metal oxide film, and a metal oxide film was obtained on the substrate.
When the metal oxide film was measured using the X-ray diffraction apparatus, it was confirmed that a titanium oxide film was formed. Furthermore, as a result of measuring the said metal oxide film with the photoelectron spectroscopy analyzer (the product made by VG Scientific, ESCALAB 200i-XL), it has confirmed that the titanium oxide film was forming. Moreover, it was 600 nm when the film thickness of the said metal oxide film was measured using the scanning electron microscope (SEM).

[Examples 5 to 45]
In Examples 5 to 45, a metal oxide film was formed on a substrate under the experimental conditions shown in Tables 1 to 9 below. Note that the method for forming the metal oxide film and the method for measuring physical properties are the same as in Example 4. The oxidizing agent and the reducing agent were added at the time of preparing the metal oxide forming solution, a naflon bubbler (manufactured by ASONE) was used for bubbling, and HB400X-21 manufactured by SEN Special Light Source Co., Ltd. was used as the ultraviolet irradiation device. As a hand spray, spray gun No. 8012 was used, and NE-U17 manufactured by OMRON Corporation was used as an ultrasonic nebulizer.
Further, the glass / TiO ₂ substrate is obtained by applying TiO ₂ fine particles in a paste form on glass. As a specific production method, first, water and isopropyl alcohol as a solvent were mixed with titanium oxide fine particles having a primary particle size of 20 nm (manufactured by Nippon Aerosil Co., Ltd., P25) 37.5% by weight, acetylacetone 1.25% by weight, polyethylene glycol ( (Average molecular weight 3000) was added to 1.88% by weight, and a slurry in which the above sample was dissolved and dispersed using a homogenizer was prepared. This slurry was applied on a glass substrate by the doctor blade method, left for 20 minutes, and dried at 100 ° C. for 30 minutes. Then, it baked in an atmospheric pressure atmosphere for 30 minutes at 500 degreeC using the electric muffle furnace (made by Denken, P90). Thereby, a glass substrate with a porous titanium oxide film was obtained.

  Table 1 shows types of reducing agents, oxidizing agents, auxiliary ion sources, and spray devices used in Tables 2 to 9. Tables 2 to 5 show specific experimental conditions of the first metal oxide film forming step (metal oxide crystal nucleus forming step) using the first metal oxide film forming solution. 9 shows specific experimental conditions for the second metal oxide film forming step (metal oxide film growing step) using the second metal oxide film forming solution. In addition, the film thickness shown to Table 6-Table 9 shows the total value of a 1st metal oxide film and a 2nd metal oxide film. As for any result in Examples 4-45, it was confirmed that the metal oxide film is formed in the photoelectron spectroscopy analyzer (ESCA).

It is explanatory drawing which shows an example of the manufacturing method of the metal oxide film of this invention. It is a relationship figure (Pourbaix diagram) which shows the relationship between pH with respect to cerium, and an electrical potential difference. It is explanatory drawing which shows an example of the manufacturing method of the 1st metal oxide film in a 1st metal oxide film formation process. It is explanatory drawing which shows the other example of the manufacturing method of the 1st metal oxide film in a 1st metal oxide film formation process. It is explanatory drawing which shows the other example of the manufacturing method of the 1st metal oxide film in a 1st metal oxide film formation process. It is explanatory drawing which shows the other example of the manufacturing method of the 1st metal oxide film in a 1st metal oxide film formation process. It is explanatory drawing which shows an example of the manufacturing method of the metal oxide film in a 2nd metal oxide film formation process. It is explanatory drawing which shows the other example of the manufacturing method of the metal oxide film in a 2nd metal oxide film formation process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Solution for 1st metal oxide film formation 3 ... 1st metal oxide film 4 ... Solution for 2nd metal oxide film formation 5 ... Spray apparatus 6 ... Metal oxide film 7, 8 ... Roller 9 ... Pump 10 ... Ultraviolet light 11-13 ... Roller

Claims (12)

A first metal oxide film is formed on the base material by contacting the base material with a solution for forming a first metal oxide film in which at least one of an oxidizing agent and a reducing agent is dissolved as a metal salt or metal complex as a metal source. A first metal oxide film forming step for forming a material film;
The substrate provided with the first metal oxide film is heated to a temperature equal to or higher than the metal oxide film forming temperature at which the metal element constituting the metal source contained in the second metal oxide film forming solution is combined with oxygen. A second metal oxide film forming step of obtaining a second metal oxide film by contacting with the second metal oxide film forming solution in which a metal salt or a metal complex is dissolved as the metal source,
The first metal oxide film forming step is a step of forming the first metal oxide film by wet coating using the first metal oxide film forming solution under a temperature condition of 50 to 150 ° C. ,
In the second metal oxide film forming step, the second metal oxide film formation is performed by bringing the second metal oxide film forming solution into contact with the base material as droplets under a temperature condition of 400 to 1000 ° C. the solvent instantaneously evaporate the use solution, Ri step der of forming the second metal oxide film,
The first metal oxide film, method for producing a metal oxide film, wherein the metal oxide film der Rukoto comprising a main element forming the second metal oxide film.   2. The metal oxide film according to claim 1, wherein when the first metal oxide film-forming solution and the base material are brought into contact with each other, an oxidizing gas is brought into contact with a portion where both are in contact with each other. Manufacturing method.   The method for producing a metal oxide film according to claim 2, wherein the oxidizing gas is oxygen or ozone.   The metal oxide according to any one of claims 1 to 3, wherein ultraviolet rays are irradiated when the first metal oxide film forming solution and the substrate are brought into contact with each other. A method for producing a membrane.   The said 2nd metal oxide film formation solution is sprayed, It is made to contact with the base material provided with said 1st metal oxide film, The claim in any one of Claim 1 to 4 characterized by the above-mentioned. The manufacturing method of the metal oxide film as described in 2.   The metal oxide film according to any one of claims 1 to 5, wherein the second metal oxide film forming solution contains at least one of an oxidizing agent and a reducing agent. Production method.   The method for producing a metal oxide film according to claim 6, wherein the second metal oxide film forming solution contains hydrogen peroxide or sodium nitrite as an oxidizing agent.   The method for producing a metal oxide film according to claim 6 or 7, wherein the second metal oxide film forming solution contains a borane complex as a reducing agent.   Metal sources used for the first metal oxide film forming solution are Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ag, In, Sn. 9. The method according to claim 1, further comprising at least one metal element selected from the group consisting of Ce, Sm, Pb, La, Hf, Sc, Gd, and Ta. The manufacturing method of the metal oxide film as described in a term. Metal sources used in the second metal oxide film forming solution are Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ag, In, Sn At least one metal element selected from the group consisting of Ce, Sm, Pb, La, Hf, Sc, Gd, Ta, Cr, Ga, Sr, Nb, Mo, Pd, Sb, Te, Ba, and W It contains, The manufacturing method of the metal oxide film of any one of Claim 1- Claim 9 characterized by the above-mentioned.   At least one of the first metal oxide film forming solution and the second metal oxide film forming solution is chlorate ion, perchlorate ion, chlorite ion, hypochlorite ion, bromate ion, 11. The metal according to claim 1, comprising at least one ionic species selected from the group consisting of hypobromide ions, nitrate ions, and nitrite ions. Manufacturing method of oxide film.   The method for producing a metal oxide film according to any one of claims 1 to 11, wherein the second metal oxide film forming solution further contains ceramic fine particles.

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