JP3887926B2 - Production method of transparent thick film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the production how transparent thick film by electrophoretic deposition of organic-inorganic composite particles, in particular, the protective film of the substrate, an optical film, or useful as a substitute for the thin glass by conventional polishing method, micro-optical application of the device is about the high-quality production how transparent thick as possible.
[0002]
[Prior art]
Conventionally, various proposals have been made for a method for producing a thick film by electrophoretic electrodeposition. For example, in JP-A-5-246701, tetraethoxysilane is dissolved in isopropyl alcohol, and diluted aqueous ammonia is added thereto. Furthermore, it has been reported that a thick silica film having a thickness of about several tens of μm is formed on an anodized aluminum substrate by using a further stirred solution as an electrophoretic electrodeposition bath.
[0003]
In addition, dilute aqueous ammonia is added to an ethanol solution of tetraethoxysilane, sodium dodecyl sulfate is added for the purpose of controlling the particle size, charge and dispersibility, and a solution in which 1,4-dioxane is further added as a drying inhibitor. It has also been reported that a silica thick film having a thickness of several μm is formed on a stainless steel substrate as an electrophoretic electrodeposition bath (1994 Ceramic Society of Japan Annual Meeting Proceedings 2H08, p513).
[0004]
[Problems to be solved by the invention]
However, in the conventional method, the resulting thick film is clouded due to particle scattering, and it is difficult to obtain a transparent thick film. In addition, the conventional method has a limitation that the thickness of the thick film to be formed is limited, and when a thick film is formed, the quality of the film tends to deteriorate.
[0005]
For this reason, the thick film by the conventional method is unsuitable for application to the protective film of the substrate, the optical film, the thin glass by the conventional polishing method, and further to the micro optical element.
[0006]
The present invention solves the above-mentioned conventional problems and greatly improves the transparency of the obtained electrodeposition film in the formation of a thick film by the electrophoretic electrodeposition method, and can be formed without causing film deterioration. Transparent thick film that can increase the film thickness and can be obtained as a protective film for a substrate with a transparent thick film, an optical film, a thin glass substitute by a conventional polishing method, and a micro optical element an object of the present invention is to provide a manufacturing how.
[0007]
[Means for Solving the Problems]
In the method for producing a transparent thick film of the present invention, at least a surface of a conductive substrate is immersed in a dispersion of organic-inorganic composite particles, and a voltage is applied between the counter electrode installed in the solution and the substrate. Applying the electrophoretic electrodeposition of the organic-inorganic composite particles to the conductive surface of the substrate, and then uniformly melting the electrodeposited film formed on the substrate to obtain a transparent thickness of 3 to 20 μm. A method of forming a film, wherein the organic-inorganic composite particles have the general formula PhMR ′ _{x + y−1} (where Ph is a phenyl group, M is a positive ion of valence (x + y), and R ′ is hydrolytic polycondensable. A composite particle having one or more compounds represented by (a functional group) as a starting material.
[0008]
The electrodeposited film formed by the electrophoretic electrodeposition method using the organic-inorganic composite particles according to the present invention can be uniformly melted by applying external energy such as heat, light, plasma, pressure, and reactive gas. As a result, the electrodeposited film is made non-porous and becomes a very homogeneous transparent thick film without micropores.
[0009]
Further, as a method for uniformly melting the electrodeposition film, a method by heat treatment is suitable .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described in detail below.
[0011]
First, the starting material for the organic-inorganic composite particles according to the present invention will be described. In the compound represented by the general formula PhMR ′ _{x + y−1} used as the starting material (hereinafter sometimes simply referred to as “starting material”), Ph is a phenyl group. Examples of the functional group R ′ capable of hydrolysis and polycondensation include alkoxy groups such as ethoxy group and methoxy group, and halogens such as chloro and bromo. Examples of positive ions M include Si, Ti, Al, B, P, Ta, Zr, V, and W.
[0012]
Specific examples of the starting material include phenyltriethoxysilane, phenyltrimethoxysilane, phenyltrichlorosilane, benzyltrichlorosilane, benzyltriethoxysilane, p-aminophenyltriethoxysilane, and tolyltrichlorosilane. Of these, phenyltriethoxysilane, phenyltrimethoxysilane, phenyltrichlorosilane and the like are preferable.
[0013]
The said starting material can be used individually by 1 type or in combination of 2 or more types. In addition to the above starting materials, a compound represented by the general formula MR ′ _{x + y} (M, R ′, x, y are the same as defined above) may be used in combination.
[0014]
The method for producing the organic-inorganic composite particles according to the present invention from the starting material is not particularly limited. For example, a method for producing the particles under basic conditions after hydrolyzing the starting material under acidic conditions. (Abstracts of the 32nd Glass and Photonics Material Discussion Meeting (1991) p139-140). Specifically, an acid such as hydrochloric acid is added to the starting material at a pH of about 2 to 3, and water is added at a molar ratio of about 4 to 10 times with respect to the starting material for hydrolysis, and ammonia or the like is added to the resulting sol. The alkali is added and the particles are grown at a pH of about 11-13.
[0015]
The particle diameter of the organic / inorganic composite particles is preferably 0.1 to 1.0 μm. Therefore, when the particle diameter is large, the organic / inorganic composite particles are appropriately pulverized.
[0016]
In preparing the electrodeposition liquid, various dispersion media for dispersing the organic-inorganic composite particles can be used depending on the purpose, and the solution used for preparing the organic-inorganic composite particles is used as it is as the electrodeposition liquid. You can also. In addition, the prepared organic-inorganic composite particles are once collected using a technique such as centrifugation, and after drying, heat treatment, pulverization, etc., if necessary, redispersed in an appropriate dispersion medium and electrodeposition. It can also be used as a liquid. In this case, as the dispersion medium, for example, a mixed solution of water and alcohols such as methanol, ethanol and propanol, ketones such as acetone and methyl ethyl ketone, ethers such as methyl ether, or methyl cellosolve is used. In particular, water: alcohol = 1: 1 to 2 (volume ratio) is preferable. In addition, it is preferable that the density | concentration of the organic inorganic composite particle in an electrodeposition liquid shall be 0.1-10 vol%. In addition, a surfactant can be added to the electrodeposition liquid for the purpose of controlling the surface charge of the organic-inorganic composite particles. In this case, examples of the surfactant include sodium dodecylbenzenesulfonate and sodium dodecylsulfate, and the addition concentration is preferably 0.01 to 0.08 wt%.
[0017]
In the present invention, as a substrate on which an electrodeposition film is formed by electrophoretic electrodeposition, a metal or alloy such as iron, steel, aluminum, copper or nickel, or a glass or plastic having a conductive thin film such as ITO formed on the surface Is used. In particular, in order to fully utilize the characteristics of the transparent thick film obtained in the present invention, it is expected to be applied to display elements and optical elements using glass substrates. It is preferable to use a glass plate on which a conductive thin film is formed. In this case, examples of the glass material of the glass substrate include quartz glass, soda lime glass, alkali aluminosilicate glass, alkali borosilicate glass, multicomponent non-alkali glass, and low expansion crystallized glass.
[0018]
On the other hand, as the counter electrode, platinum, stainless steel, graphite, titanium or the like which is not easily eroded by alkali or acid can be used.
[0019]
The applied voltage is preferably in the range of 5 to 200 V, and a direct current or pulse voltage is applied so that the substrate side becomes the anode.
[0020]
After the electrodeposition film is formed on the substrate by applying such a voltage, the substrate is pulled up from the electrodeposition solution to uniformly melt the electrodeposition film. That is, the composite particles aggregated and laminated on the substrate by electrophoretic electrodeposition are uniformly melted by applying external energy such as heat, light, plasma, pressure, and reactive gas. Thereby, the electrodeposition film is made nonporous and a transparent thick film is formed.
[0021]
This melting is particularly preferably carried out by heat treatment. In this case, the heat treatment conditions generally vary depending on the thickness of the transparent thick film to be formed, the kind of the organic-inorganic composite particles used, etc., but generally at 200 to 500 ° C. About 20 minutes.
[0022]
According to such a method of the present invention, it is possible to form a transparent thick film having good transparency with a light transmittance in the visible range of 70% or more. Further, the film thickness can be increased to 3 to 20 μm by adjusting electrodeposition conditions such as applied voltage and electrodeposition time during electrodeposition.
[0023]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0024]
Example 1
Phenyltriethoxysilane was hydrolyzed at room temperature for 10 hours in the presence of a hydrochloric acid catalyst (pH 2.8). Here, the diluted hydrochloric acid used for the hydrolysis was 0.01 wt%, and water was 20 times in molar ratio with respect to phenyltriethoxysilane. The transparent homogeneous sol obtained by the above hydrolysis was slowly added to 10 times amount of 4 wt% ammonia water (pH 12), and further stirred at room temperature for 10 hours. By this operation, the solution was suspended in white, and formation of particles was confirmed.
[0025]
The resulting phenyl-modified silica particles were collected by centrifugation and dried in a vacuum oven for 3 hours. The particle size of the phenyl group-modified silica particles after the drying operation was about 0.1 to 1 μm. The particles were easily pulverized in an agate mortar to a particle size of 0.1 to 1 μm, then added to a mixed solvent of water-ethanol = 1: 1 volume ratio so as to be 1.0 vol%, and subjected to ultrasonic irradiation The electrodeposition bath in which the phenyl group-modified silica particles are uniformly dispersed was prepared.
[0026]
A soda lime glass substrate having an ITO conductive film formed on the surface was immersed in this electrodeposition bath facing the counter electrode, and a DC voltage of 40 V was applied for 5 minutes so that the substrate would be an anode. On the conductive film of the substrate, a white opaque electrodeposition film in which phenyl group-modified silica particles were deposited was formed. The substrate on which the electrodeposition film was formed was oven-heated at 200 ° C. for 2 hours, whereby the white opaque electrodeposition film became a transparent thick film. When the thick film before and after the heat treatment was observed with an electronic scanning microscope, it was observed that spherical particles having a particle size of 0.1 to 1 μm were deposited on the substrate before the heat treatment. It was confirmed that the film was melted to form a dense homogeneous film. The thick film after the heat treatment had a film thickness of about 5 μm, and showed a high light transmittance of 80% in the visible region.
[0027]
The film thickness could be further increased by controlling the electrodeposition conditions.
[0028]
Example 2
Phenyltriethoxysilane and tetraethoxysilane were hydrolyzed at room temperature for 10 hours in the presence of hydrochloric acid catalyst (pH 2.5). Here, the molar ratio of phenyltriethoxysilane and tetraethoxysilane was 90:10. The dilute hydrochloric acid used for the hydrolysis was 0.01 wt%, and water was 20 times in molar ratio with respect to the total amount of phenyltriethoxysilane and tetraethoxysilane. The transparent homogeneous sol obtained by the above hydrolysis was slowly added to 10 times amount of 4 wt% ammonia water (pH 12), and further stirred at room temperature for 10 hours. By this operation, the solution was suspended in white, and formation of particles was confirmed.
[0029]
The resulting phenyltriethoxysilane-tetraethoxysilane derived phenyl group modified silica particles were collected by centrifugation and dried in a vacuum oven for 3 hours. The particle size of the phenyltriethoxysilane-tetraethoxysilane-derived phenyl group-modified silica particles after the drying operation was about 0.1 to 1 μm. Using these particles, an electrodeposition bath was prepared in the same manner as in Example 1, and electrophoretic electrodeposition was performed on a soda lime glass substrate on which an ITO transparent conductive film was similarly formed.
[0030]
The electrodeposition film formed by electrodeposition on which phenyltriethoxysilane-tetraethoxysilane-derived phenyl group-modified silica particles were deposited was also white opaque, but it became white opaque by performing oven heating at 500 ° C. for 2 hours. The electrodeposition film became a transparent thick film. When the thick film before and after the heat treatment was observed with an electronic scanning microscope, it was observed that spherical particles having a particle diameter of 0.1 to 1 μm were deposited on the substrate before the heat treatment, but these particles were melted after the heat treatment. It was confirmed that the film was a dense homogeneous film. The thick film after the heat treatment had a film thickness of about 5 μm, and showed a high light transmittance of 73% in the visible region.
[0031]
The film thickness could be further increased by controlling the electrodeposition conditions.
[0032]
Comparative Example 1
Methyltriethoxysilane was hydrolyzed for 1 hour at room temperature in the presence of hydrochloric acid catalyst. Here, dilute hydrochloric acid used for hydrolysis was 0.01 wt%, and water was 20 times in molar ratio with respect to methyltriethoxysilane. The transparent homogeneous sol obtained by the above hydrolysis was slowly added to 10 times amount of 4 wt% ammonia water, and further stirred at room temperature for 10 hours. By this operation, the solution was suspended in white, and formation of particles was confirmed.
[0033]
The resulting methyl group-modified silica particles were collected by centrifugation and dried in a vacuum oven for 3 hours. The particle size of the methyl group-modified silica particles after the drying operation was about 0.1 to 1 μm. Using these particles, an electrodeposition bath was prepared in the same manner as in Example 1, and electrophoretic electrodeposition was performed on a soda lime glass substrate on which an ITO transparent conductive film was similarly formed.
[0034]
The electrodeposition film formed by electrodeposition and deposited with methyl group-modified silica particles was white and opaque.
[0035]
Although the thickness of the thick film obtained by this operation was about 5 μm, the thick film remained white and opaque even after being heated at 200 ° C., 400 ° C., and 600 ° C. for 2 hours. A film could not be obtained.
[0036]
Comparative Example 2
Tetraethoxysilane was hydrolyzed in an ethanol-water solvent at room temperature for 10 hours in the presence of an ammonia catalyst. Here, ammonia used for hydrolysis was 1 wt%, ethanol and water were both 50 times in molar ratio with respect to tetraethoxysilane, and 0.02 vol% sodium dodecyl sulfate was used to control the particle size. Added. Silica particles obtained by the above hydrolysis were collected by centrifugation, dried in a vacuum oven for 3 hours, and further heat-treated at 600 ° C. Using the obtained particles, an electrodeposition bath in which the silica particles are 1 vol% is prepared in the same manner as in Example 1, and further, a cationic polymer surfactant polyethyleneimine is added to the electrodeposition bath in an amount of 0.1 to 1 vol%. Electrophoretic electrodeposition was performed in the same manner except that the soda lime glass substrate on which the ITO transparent conductive film was added became a cathode. The silica particle-polymer surfactant polyethyleneimine composite film formed by electrodeposition had a film thickness of about 5 μm, but was cloudy, and this was oven-heated at 400 ° C. and 600 ° C. for 2 hours, respectively. It remained cloudy afterwards and did not become transparent.
[0037]
【The invention's effect】
As described above in detail, according to the present invention, a good transparent thick film excellent in homogeneity and transparency can be formed by the electrophoretic electrodeposition method.
[0038]
Therefore, according to the present invention, a substrate with a transparent thick film by electrophoretic electrodeposition can be applied to a display element and an optical element.

Claims (1)

In the dispersion liquid of organic-inorganic composite particles, at least the surface of the conductive substrate is immersed, and a voltage is applied between the counter electrode and the substrate placed in the liquid to form the conductive surface of the substrate. A method of electrophoretic electrodeposition of the organic-inorganic composite particles, and then uniformly melting the electrodeposition film formed on the substrate to form a transparent thick film having a thickness of 3 to 20 μm,
The organic-inorganic composite particle is a compound represented by the general formula PhMR ′ _{x + y−1} (where Ph is a phenyl group, M is a positive ion of valence (x + y), and R ′ is a functional group capable of hydrolysis polycondensation). A method for producing a transparent thick film, which is a composite particle using one or more of the above as starting materials.