JP3381429B2 - Method for producing substrate with metal oxide film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a substrate having a metal oxide film formed thereon by electrophoresis.

[0002]

Conventionally, metal oxide onto a substrate (such as silica, titania, etc. A) As a method for forming a film, for example, in JP-A-5-246701, tetraethoxysilane dissolved in isopropyl alcohol, to It has been reported that a thick silica film having a thickness of about several tens of μm can be formed on an anodized aluminum substrate by using a solution obtained by adding diluted ammonia water and further stirring it as an electrophoretic electrodeposition bath.

Dilute aqueous ammonia was added to an ethanol solution of tetraethoxysilane, sodium dodecyl sulfate was added for the purpose of controlling particle size, charge and dispersibility, and 1,4-dioxane was added as a drying inhibitor. It has been reported that a solution can be used as an electrophoretic electrodeposition bath to form a silica film having a thickness of several μm on a stainless steel substrate (1994 Proceedings of the Ceramic Society of Japan Annual Meeting 2H08 P.513).

[0004]

However, the metal oxide film obtained by the above-mentioned electrophoretic electrodeposition method often has insufficient adhesion to the substrate, and the film is opaque. Many. These tendencies are more remarkable when a thick film is formed, and it is difficult to obtain a film having a sufficient thickness. This was a big problem in putting the obtained film into practical use.

The present invention improves the adhesion of a metal oxide film obtained by an electrophoretic electrodeposition method on various conductive substrates and dielectric substrates to which conductivity is imparted, and also provides a transparent metal oxide film. Is intended to be formed.

[0006]

The present invention provides a method for electrophoretic electrodeposition of metal oxide colloids in a water-organic solvent system solution, in particular using metal colloids with controlled particle size , And the finding that it is effective in improving the transparency, and the addition of an organometallic compound such as methyltriethoxysilane into the solution exerts a remarkable drying suppressing effect on the obtained electrodeposition film, It was achieved by the knowledge.

In the present invention, in particular, a metal oxide colloid having a controlled particle size, an organic metal compound having an effect of suppressing the drying of the film, a solution containing water, alcohol and a base as a component is electrically conductive to the conductive substrate or its surface. The dielectric substrate provided with the property is immersed. Then, a voltage is applied between the counter electrode and the counter electrode placed in the solution to mainly deposit the metal oxide colloid on the conductive substrate or the dielectric substrate having conductivity on its surface. By heat treating, it is possible to obtain a transparent substrate with a metal oxide electrodeposition film, which has high adhesion to the substrate.

The metal oxide colloid used in the present invention includes SiO ₂ , TiO ₂ , ZrO ₂ and Al.
₂ O ₃ , Sb ₂ O _{5 and the} like can be mentioned. These metal oxide fine particles can be obtained by preparing in the gas phase by the CVD method or the like. Also, the hydrolyzed sol is grown in the liquid phase and collected by centrifugation or filtration. The collected particles are optionally calcined to control surface properties. The fine particles obtained from the gas phase and the liquid phase are dispersed in a solvent by a predetermined method and used as a metal oxide colloid. Among the metal oxides, SiO
₂ Colloids are preferable because those having a controlled particle size are easy to prepare.

The metal oxide colloid having an arbitrary particle size can be used according to the purpose. Especially in the case of silica particles,
It is preferable that the average particle diameter is about 1 to 500 nm.
If the average particle size is larger than 500 nm, it becomes difficult to obtain a transparent film. Further, generally, as the size of the particles increases, the surface area per unit mass decreases, and therefore the amount of charge per unit mass also decreases, making it difficult to perform electrophoretic electrodeposition.

Further, when the silica particles are hydrolyzed and polycondensed with tetraethoxysilane in a liquid phase, collected by centrifugation, and then calcined, when the calcining is performed after electrophoretic electrodeposition, The silica particle electrodeposition film is characterized by small shrinkage and few cracks.

The metal oxide colloid may have any particle size depending on the purpose, but it is desirable that the particle size is as uniform as possible. This is because, as with the above-mentioned reason, if the particle diameter of the metal oxide colloid is uniform, the charge thereof is also uniform, and thus good electrophoresis can be performed. As a result, a film having good adhesion can be obtained.

The concentration of the metal oxide colloid in the electrophoretic electrodeposition solution is preferably in the range of 0.1% by weight to 15% by weight. Further, about 1% by weight is practically preferable.

In the present invention, the organometallic compound added to the electrophoretic electrodeposition solution is preferably a silicon organometallic compound having a hydrolysis-condensation-polymerizable functional group and a hydrolysis-polycondensation-inactive functional group.

As the organometallic compound of silicon,
Monoalkyltrialkoxysilanes such as methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, and ethyltripropoxysilane, and dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxy. Examples thereof include dialkyldialkoxysilanes such as silane, diethyldimethoxysilane, diethyldiethoxysilane, and diethyldipropoxysilane. Further, monophenyltrialkoxysilane and monovinyltrialkoxysilane can also be used.

Further, monoalkyltrichlorosilane such as methyltrichlorosilane, ethyltrichlorosilane and propyltriethoxysilane, and dialkyldichlorosilane such as dimethyldichlorosilane, diethyldichlorosilane and dipropyldiethoxysilane can also be used.

The concentration of the organometallic compound in the electrophoretic electrodeposition solution is preferably in the range of 0.1% by weight to 10% by weight. Further, about 1% by weight is practically preferable.

The reason for adding this organometallic compound to the electrophoretic electrodeposition solution is as follows. It is considered that this organometallic compound is adsorbed in a small amount on the metal oxide colloid in the solution, and when the metal oxide film is electrodeposited on the substrate in the solution and the substrate is pulled out from the solution. In addition, it is considered that the electrodeposited film is prevented from being rapidly dried in the air to prevent the film surface from being cracked.

The organic solvent is used for dispersing the metal oxide fine particles and is not particularly limited as long as it is compatible with the organometallic compound, water and base. Alcohols such as methanol, ethanol, propanol, butanol,
Ketones such as acetone and methyl ethyl ketone are used.

The base is added so that the water added to the electrophoretic electrodeposition solution becomes alkaline. Specifically, pH = 1
Ammonia water of 0 to 13 is added to the organic solvent in a molar ratio of about 1: 1. Particularly, ammonia water added has a pH of 11.7.
The thing of a grade is suitable.

In the substrate provided with the metal oxide electrodeposition film by the electrophoretic method of the present invention, the metal oxide colloid containing a trace amount of the organometallic compound is strongly deposited and adhered to the substrate immediately after the film formation. The trace amount of organometallic compound means an amount on the order of ppm. This organometallic compound has a decomposition temperature of the organic functional group around 500 ° C., although it depends on the kind. Therefore, below the decomposition temperature, organic functional groups are present in the film, and above the decomposition temperature, the electrodeposited film is a complete metal oxide.

Metals such as iron, steel, aluminum, copper, nickel, chromium and titanium, and alloys thereof can be used as the substrate for forming the metal oxide electrodeposition film by the electrophoresis method. Further, a dielectric substrate such as glass or plastic having a conductive film such as ITO, metal or alloy formed on its surface can be used. These coatings are known C
It can be formed by various methods such as the VD method, the sputtering method and the vapor deposition method.

As the counter electrode used in the present invention, platinum, stainless steel, graphite, titanium or the like which is not easily corroded by alkali can be used.

When electrodepositing negatively charged metal oxide fine particles in a solution of SiO ₂ , TiO ₂ , ZrO ₂ or the like on a substrate, an electric field is applied so that the substrate serves as an anode. On the other hand, Al
_When electrodepositing metal oxide fine particles that are positively charged in a solution such as ₂ O ₃ or ITO, an electric field is applied so that the substrate serves as a cathode. The voltage is in the range of 5 to 200 V, and may be DC voltage or pulse voltage.

Further, a surfactant may be added to the electrophoretic electrodeposition solution, if necessary, for the purpose of controlling the surface charge of the metal oxide colloid.

[0025]

In the present invention, a metal oxide electrodeposition film is formed by an electrophoretic method using a metal oxide colloid having a controlled particle size and a solution containing an organometallic compound having a film drying suppressing effect. Therefore, it is possible to obtain a transparent substrate with a metal oxide electrodeposition film, which has high adhesion to the substrate.

[0026]

【Example】

(Example 1) After tetraethoxysilane was hydrolyzed and polycondensed in a liquid phase, it was collected by centrifugation and calcined at 600 ° C. The obtained silica particles have an average particle size of about 140 nm.
It was. Methyltriethoxysilane 3.
A dispersion solvent consisting of 64 g, 1% by weight aqueous ammonia (18.59 g) and ethanol (47.06 g) was stirred at room temperature for 1 hour to uniformly disperse the solution to obtain an electrophoretic electrodeposition solution.

A stainless steel substrate (SUS430) was used as a substrate in the obtained solution, and this was immersed as an anode,
A DC voltage of 10 V was applied for 2 minutes. Here, a stainless wire (SUS304, φ0.9 mm) in the form of a coil was used as the counter electrode.

By the above operation, a stainless steel substrate with a silica particle electrodeposition film having a film thickness of about 5 μm was obtained. The obtained thin film was transparent and had a high adhesive force to the substrate, and no crack was observed when the film was dried. From the results of thermal analysis and IR spectrum measurement, it was found that several ppm of methyl groups were present inside the film after electrodeposition.

The SUS substrate with the electrodeposited silica film was
By baking at 0 ° C. for 1 hour and further at 800 ° C. for 1 hour, a slight amount of methyl groups present in the film were completely decomposed by combustion, and the film thickness was about 4 μm by sintering. However, generation of film cracks due to shrinkage and deterioration of transparency were not observed at all.

Example 2 The same operation as in Example 1 was performed using a quartz glass substrate having a transparent conductive ITO film as a base.

As a result, a silica glass substrate with a silica particle electrodeposition film having a film thickness of about 5 μm after drying was obtained. The film obtained in the same manner as in Example 1 was transparent, had high adhesiveness to the substrate, and no cracks were observed when the film was dried. From the results of thermal analysis and IR spectrum measurement, it was found that several ppm of methyl groups were present inside the film after electrodeposition.

The quartz glass substrate with the electrodeposited silica film is
By baking at 400 ° C. for 1 hour and further at 800 ° C. for 1 hour, the methyl groups present in the trace amount film were completely burned and decomposed, and the film thickness became about 4 μm by sintering. However, generation of film cracks due to shrinkage and deterioration of transparency were not observed at all.

(Example 3) Silica particles (average particle size 10 nm) prepared by the vapor phase method were mixed with 3.64 g of methyltriethoxysilane, 18.59 g of 1% by weight aqueous ammonia,
1 at room temperature in a dispersion solvent consisting of 47.06 g of ethanol.
The solution was uniformly dispersed by stirring for a time to obtain an electrophoretic electrodeposition solution.

A stainless steel substrate (SUS430) was used as a substrate in the obtained solution, which was immersed as an anode, and a DC voltage of 10 V was applied for 2 minutes. Here, in the counter electrode,
A coil of stainless steel wire (SUS304, φ0.9 mm) was used.

By the above operation, a stainless steel substrate with an electrodeposition film made of silica particles having a thickness of about 5 μm was obtained. The obtained film was transparent, had high adhesiveness to the substrate, and no cracks were observed when the film was dried. From the results of thermal analysis and IR spectrum measurement, it was found that several ppm of methyl groups were present inside the film after electrodeposition.

S with an electrodeposited silica film by the above-mentioned electrophoresis method
When the US substrate was baked at 400 ° C. for 1 hour and further at 1000 ° C. for 1 hour, the methyl groups, which were present in a trace amount in the film, were completely combusted and decomposed, and the film thickness was about 1 μm by sintering. However, the occurrence of film cracks due to shrinkage,
No decrease in transparency was observed.

(Example 4) Transparent conductive ITO as a substrate
Example 3 except that a quartz glass substrate having a film formed thereon was used.
The same operation was performed.

As a result, a silica glass substrate with a silica particle electrodeposition film having a film thickness of about 5 μm after drying was obtained. The film obtained in the same manner as in Example 3 was transparent, had a high adhesive force to the substrate, and no cracks were observed when the film was dried. It was also found that the film after electrodeposition had several ppm of methyl groups present inside the film.

The quartz glass substrate with the electrodeposited silica film is
By firing at 400 ° C. for 1 hour and further at 1000 ° C. for 1 hour, a slight amount of methyl groups present in the film was completely combusted and decomposed, and the film thickness became about 1 μm by sintering. However, generation of film cracks due to shrinkage and deterioration of transparency were not observed at all.

(Comparative Example 1) Tetraethoxysilane was hydrolyzed and polycondensed in a liquid phase, collected by centrifugation, and calcined at 600 ° C.
The obtained silica particles had an average particle size of about 140 nm. This was uniformly dispersed in a dispersion solvent consisting of 18.59 g of 1% by weight ammonia water and 47.06 g of ethanol at room temperature for 1 hour to prepare an electrophoretic electrodeposition solution.

A stainless steel substrate (SUS430) was used as a substrate in the obtained solution, and this was immersed as an anode,
A DC voltage of 10 V was applied for 2 minutes. Here, a stainless wire (SUS304, φ0.9 mm) in the form of a coil was used as the counter electrode.

By the above operation, a stainless steel substrate with a silica particle electrodeposition film having a thickness of about 5 μm was obtained. However, the obtained film had weak adhesion to the substrate, and cracks were generated on the entire surface of the film when the film was dried.

From the comparison with Example 1, it was found that a slight amount of methyl groups in the film due to methyltriethoxysilane added in the dispersion solvent played a large role in improving the film adhesion and preventing the occurrence of cracks. Became clear.

[0044]

In the present invention, since the metal oxide electrodeposition film is formed from a solution containing a metal oxide colloid with a controlled particle size and an organometallic compound having a film drying suppressing effect, It was possible to obtain a transparent substrate with a metal oxide electrodeposition film, which had a high adhesion to the substrate. Further, if the metal oxide colloid is silica particles prepared by a liquid phase method, there is an advantage that film shrinkage due to firing is small and cracks do not occur.

This substrate with a metal oxide electrodeposition film remarkably improves the corrosion resistance and weather resistance when the substrate is, for example, a metal, and can be widely used in fields requiring reliability. Is. Furthermore, since the metal oxide film obtained by the method of the present invention has good transparency, it is possible to form this metal oxide film on a transparent substrate such as a glass substrate to which conductivity is imparted by a transparent conductive film or the like. The present technology can be applied to optical elements.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method for producing a substrate with a metal oxide electrodeposition film according to the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Kishimoto 3-5-11 Doshomachi, Chuo-ku, Osaka City, Osaka, Japan Sheet Glass Co., Ltd. (56) Reference JP-A-58-81995 (JP, A) ( 58) Fields investigated (Int.Cl. ⁷ , DB name) C25D 13/10 C01B 33/12 C04B 41/85 C25D 13/00 307 C25D 13/02

Claims (3)

(57) [Claims] 1. A metal oxide colloid, an organometallic compound,
A conductive substrate or a dielectric substrate whose surface has been made conductive is immersed in a solution containing water, alcohol and a base, and a voltage is applied between the conductive substrate and a counter electrode placed in the solution to conduct the conductivity. A method for producing a substrate with a metal oxide film, characterized in that the metal oxide colloid is electrophoresed on the surface of a conductive substrate or the dielectric substrate to form an electrodeposition film, and the deposited film is heat-treated. 2. The metal oxide colloid has an average particle size of 1 to 5.
The method for producing a substrate with a metal oxide film according to claim 1, wherein the substrate is composed of 00 nm silica particles, and the organometallic compound is a monoalkyltrialkoxysilane. 3. The method for producing a substrate with a metal oxide film according to claim 2, wherein the silica particles are silica particles obtained by hydrolyzing and polycondensing tetraethoxysilane in a liquid phase, and then collecting and calcining. .