JP2000351917A - Coating liquid for forming oxide membrane, formation of oxide membrane and substrate with oxide membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject coating liquid capable of forming a transition metal oxide membrane excellent in abrasion resistance, etc., by incorporating a specific metal salt, an alkoxide of Si, etc., and a resin and making an atomic ratio of Si to the total amount of the total metal of the metallic salt and Si as a specific value. SOLUTION: This coating liquid is obtained by incorporating (A) at least 1 kind of a metal salt selected from Co, Cr, Mn, Fe, Ni, Cu, Zn and a lanthanoid (La to Lu), (B) an alkoxide of Si (a partially hydrogenated material), (C) a resin and (D) an ethylene glycol oligomer of the formula: HO(CH2CH2O)nH [(n) is 2-8] and making >=0.28 atomic ratio of Si to the total amount of the total metal of the metallic salt and Si. As the component A, a nitric salt is preferable. Also, in the case of forming a black color-based colored membrane, as the component A, it is preferable to use a Cu salt with Mn salt simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coating solution for forming an oxide film, a method for forming an oxide film, and a substrate having an oxide film.

[0002]

2. Description of the Related Art Heretofore, many techniques have been proposed for forming an oxide film on a substrate to impart various functions. At present, as a method of forming an oxide film which is frequently used, there are a dry method such as vacuum deposition, sputtering, and CVD, and a wet method such as a sol-gel method and spray pyrolysis. Film formation by the wet method is advantageous in industrial production in that it can be formed at low cost.

The sol-gel method is a typical example of film formation by a wet method. This is a method in which a metal alkoxide is hydrolyzed, a metalloxane bond (M-O-M) is formed in a solution to form a sol, and a film is formed by coating and heating.
Proven in forming low reflection interference films and insulating films. The sol-gel method is the most frequently used method because a uniform film can be formed by appropriately controlling hydrolysis conditions and the like.

When a dense thin film made of a transition metal oxide is coated on a glass surface, the glass is colored variously by ion absorption and becomes a low-permeability colored glass whose transmittance is greatly reduced. In addition, when a dense and uniform thin film is formed, the reflectance of the light-absorbing oxide is increased as a characteristic, and the light-absorbing oxide may have a half mirror shape. Such low-permeability colored glass can protect the internal environment because it can effectively block sunlight,
It also helps protect privacy inside and inside the car.

[0005] When a transition metal oxide film is formed by the sol-gel method described above, transition metal alkoxides are not very common and are extremely expensive materials, so they are not suitable for inexpensive film formation. On the other hand, metal salts such as nitrates, chlorides, and sulfates are readily available, but these metal salts alone cannot provide a uniform and dense thin film unlike the sol-gel method, and therefore have poor wear and chemical resistance. It was difficult to obtain a thin and highly durable thin film.

Japanese Patent Application Laid-Open No. 9-30836 proposes a coating solution for forming an oxide film containing an ethylene glycol oligomer. The film obtained by applying the coating solution for forming an oxide film on a substrate is a relatively homogeneous and dense film, but the adhesion between the film and the substrate is poor. Therefore, it is unsuitable for applications requiring higher wear strength (for example, applications such as a portion of a door glass for an automobile that is repeatedly moved up and down).

[0007]

DISCLOSURE OF THE INVENTION In view of the above problems, the present invention provides a coating solution capable of easily forming a transition metal oxide film having high abrasion resistance and having few appearance defects, and using the coating solution. An object of the present invention is to provide a method for forming an oxide film and a substrate with an oxide film.

[0008]

SUMMARY OF THE INVENTION The present invention provides Co, Cr,
Mn, Fe, Ni, Cu, Zn and lanthanoids (L
a to Lu) a salt of at least one metal selected from the group consisting of: an alkoxide of Si or a partial hydrolyzate thereof;
A coating liquid containing a resin, wherein the atomic ratio of Si to the total amount of all metals and Si in the metal salt in the coating liquid is 0.2.
A coating liquid for forming an oxide film, which is 8 or more (hereinafter referred to as the present coating liquid) is provided.

According to the present coating solution, a uniform and dense transition metal oxide film containing silicon oxide can be formed. Due to its denseness and the properties unique to silicon oxide, high abrasion resistance and low reflectance equivalent to glass are obtained. Is obtained, and the appearance is sufficiently good and there is no practical problem.

Co, Cr, Mn, Fe, Ni, Cu, Z
n and salts of one or more metals selected from the group consisting of lanthanoids (La to Lu) (hereinafter simply referred to as metal salts)
As is not particularly limited as long as it is soluble in the solvent forming the coating solution, there is a high degree of freedom of solvent selection high solubility,
Nitrate is preferred because it has excellent stability when a chelate complex is formed, and the harmfulness of gas generated during thermal decomposition is relatively small. The metal salt is used singly or as a mixture of several types. When a black colored film is formed for the purpose of improving design, it is preferable to use a Cu salt and a Mn salt in combination as metal salts. Cu
And Mn form a black spinel oxide. The black colored film has a spinel oxide peak in X-ray diffraction analysis.

A generally known spinel oxide containing Co or Fe is formed by firing at a high temperature (for example, 800 ° C.) for a long time (for example, one hour or more).
And Mn spinel oxides are easy to form at relatively low temperatures,
This is extremely effective when the upper limit of the heating conditions is limited.

The composition of Cu and Mn in the present coating solution does not always match the composition in the oxide film after film formation. If the liquid composition has the same ratio as the film composition, a spinel oxide film having a sufficient absorbance may not be obtained. This is because even if the metal source of the raw material is stabilized in the present coating solution with ethylene glycol oligomer, alkoxide of Si, etc., it partially sublimates and decreases during the firing process, or in the case of high-temperature firing, the metal becomes It is considered that the ionization and migration into the glass result in a decrease in the content of Cu or Mn in the film.

The temperature at which spinel crystallization is performed, the durability of the film, the transmission color tone, and the like can be adjusted by the type and amount of other metal components added to Cu and Mn. For example, Cr
Is added, the crystals are crystallized under lower firing conditions, giving a dark gray color. In a Cr-added system, a Cr oxide that easily crystallizes at a low temperature becomes a nucleus to promote spinel crystallization of Cu or Mn, thereby forming a spinel crystal composite oxide in which part of Cu or Mn is substituted by Cr. Conceivable. As the amount of Cr added is larger, crystallization is promoted and crystallization is easy at low temperature, and the transmission color tone becomes bluish gray.
The denseness of the film decreases, and the hardness of the film decreases.

The molar ratio of Cr to the total amount of all metals and Si in the metal salt in the coating solution is preferably from 0.01 to 0.3, and particularly preferably from 0.01 to 0.1. . On the other hand, by adding Fe, Co, or the like, the durability of the film can be increased or the transmission color tone can be made closer to brown. The spinel crystallization temperature rises contrary to the case of adding Cr and may require more heating.

Further, in order to increase the absorbance of the oxide film, a noble metal compound such as ruthenium chloride, chloroauric acid, or chloroplatinic acid can be added. Further, since the chemical resistance of the oxide film can be further improved and the refractive index can be adjusted,
An alkoxide or chelate of one or more metals selected from the group consisting of l, Ti and Zr can be added.

This coating solution has a chemical formula of HO (CH ₂ CH ₂ O)
_n H (where n is an integer of 2-8) ethylene glycol oligomer (hereinafter, simply referred to as oligomers) represented by preferably contains one or more. The oligomer in the present invention has etheric oxygen in the molecule and a hydroxyl group at the terminal, and is considered to be coordinated to a metal ion via those oxygens, thereby changing the thermal decomposition behavior of the metal salt. it is conceivable that.

The oligomer in the present invention is a dimer (n = 2 in the above chemical formula) to an octamer (n = 8). With a monomer (n = 1), that is, ethylene glycol, it is difficult to form a homogeneous and dense oxide film, and the effect of addition is small. In the case of a polymer having 9 or more mers, it is difficult to obtain good results, probably because it is difficult to coordinate with metal ions.

The oligomer is used alone or in a mixture of two or more. The effect of addition is small with a propylene glycol polymer (a dense film cannot be obtained, peeling occurs, and the absorbance does not easily increase). This is probably due to the difference in the coordination state to the metal ion due to the difference in the three-dimensional structure.

Specific examples of the oligomer include diethylene glycol (n = 2) and triethylene glycol (n = 2).
3), tetraethylene glycol (n = 4), pentaethylene glycol (n = 5), hexaethylene glycol (n = 6), heptaethylene glycol (n = 7),
Octaethylene glycol (n = 8) is exemplified. In addition, polyethylene glycol # 200 (a mixture of polymers, having an average molecular weight of 200), which contains the aforementioned oligomer as a main component and is commercially available as a mixture of two or more oligomers, and polyethylene glycol # 300 (a mixture of polymers) And an average molecular weight of 300).

As the oligomer, at least one selected from the group consisting of diethylene glycol, triethylene glycol and tetraethylene glycol is preferred from the viewpoints of the density and homogeneity of the obtained oxide film or the availability. preferable. Further, polyethylene glycol # 200 is also preferably used. Oligomer is effective with a very small amount of addition, conversely, if the addition amount is too large,
Perhaps because the number of oligomers that do not participate in coordination with metal ions increases, the homogeneity of the baked oxide film is hindered, and the hardness of the film tends to decrease or the appearance tends to be impaired. In the present invention, the molar ratio of the oligomer to the total amount of all metals and Si in the metal salt in the coating liquid is preferably 0.3 or less. It is preferable that the addition amount of the oligomer be minimized.

[0021] The Si oxide precursor (Si
And the same applies hereinafter. ) Is S with respect to the total amount of all metals and Si of the metal salt.
It is contained so that the molar ratio of i becomes 0.28 or more.
When the ratio is 0.28 or more, the durability of the oxide film (particularly, abrasion resistance, which is often emphasized in practical use) is remarkably improved. The resulting oxide film has durability enough to be used for applications requiring high wear resistance, for example, door glass for automobiles.

Although the wear resistance is improved as the Si content is increased, spinel crystallization of Cu or Mn is less likely to occur. In order to promote crystallization, it is advisable to increase the amount of added Cr or perform more heating. As the content of Si which exhibits sufficient durability and does not inhibit crystallization, the molar ratio of Si to the total amount of all metals and Si in the metal salt is preferably 0.30 to 0.60.

Examples of the Si oxide precursor include monomers such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane; hexaethoxydisiloxane which is a condensate of the alkoxide;
Examples include octaethoxytrisiloxane, decaethoxytetrasiloxane, ethoxypolysiloxane, and ethyl silicate 40 which is a mixture of a monomer and a condensate.

Further, an alkylalkoxysilane in which an alkoxy group is partially substituted with an alkyl group, that is, an alkylalkoxysilane having an alkoxy group and an alkyl group is also used. Examples of the alkyl group include methyl, ethyl, propyl, butyl,
Linear or branched alkyl groups such as -ethylbutyl and octyl, and cycloalkyl groups such as cyclopentyl and cyclohexyl. As a method for synthesizing the hydrolysis product of the alkoxide of Si, a known method is used. In controlling the product, the type and amount of the alkoxide, the type and amount of the hydrolysis catalyst, the amount of water, the reaction method, the reaction time, the reaction temperature, the stirring conditions, and the like are important factors.

When adding water or a catalyst to the Si alkoxide, 1) a method of mixing the Si alkoxide and water, 2) a method of mixing the Si alkoxide and water in the presence of an acid, 3) Si And a method of mixing the alkoxide with water in the presence of an alkali. As the acid in the method 2), sulfuric acid, hydrochloric acid, nitric acid,
Phosphoric acid, acetic acid, formic acid, methanesulfonic acid and the like are preferred. In one embodiment, copper nitrate is added to a mixture of an alkoxide of Si and water to form an acidic solution. Ammonia or the like is used as the alkali in the method 3).

As the solvent used in the coating solution of the present invention, a solvent capable of simultaneously dissolving the metal salt and the oligomer and dissolving the reaction product (complex) of the metal salt and the oligomer is used. It is also effective to use a mixed solvent of two or more types from the viewpoint of leveling property (uniformity) of the coating film and suppression of color unevenness generated during drying. When two or more mixed solvents are used, one or more of them may be a solvent that dissolves the complex, and the other solvent may be a solvent that does not dissolve the complex.

Examples of the solvent include water, lower monohydric alcohols (eg, methanol, ethanol, propanol), water-soluble diols (eg, ethylene glycol, propylene glycol, hexylene glycol), ether alcohols (eg, cellosolves, carbitols), and the like. Ketones (eg, methyl ethyl ketone, methyl isobutyl ketone), esters, ethers, acetals, and the like. In addition, some of them not only serve as a solvent but also coordinate with a metal in a coating solution to form a chelate and contribute to stabilization of a metal source. For example, solvents of ether alcohol and water-soluble diol (particularly hexylene glycol) are exemplified.

In the coating film drying process, due to solvent evaporation, a change in viscosity due to the increase in molecular weight, a change in surface tension, and the like, and foreign matter and the like, unevenness in film thickness, pinholes, craters, etc. Defects are likely to occur. In addition, since the film shrinks greatly even during firing, minute cracks and cracks are likely to be formed particularly when the film is thick. It is important to add a resin to the coating solution for suppressing such appearance defects during drying and baking of the coating film.

The resin used in the present coating solution is not particularly limited as long as it is soluble in a solution comprising a metal salt and a solvent. When a nitrate is used as a metal salt, the coating solution often becomes water-soluble, and thus a water-soluble resin often used as an additive for water-based paints (leveling agent, surface conditioner, viscoelasticity adjuster). The use of is effective in increasing the solubility.

Further, other characteristics of the resin to be considered besides the solubility include the effect on the viscosity of the coating solution and the thermal decomposition temperature. Since the viscosity is closely related to the leveling property of the coating film and the appearance of the coating, it is necessary to adjust the viscosity to the properties of the coating liquid and the desired film thickness. When it is not desired to leave the resin in the film at the stage of drying and baking the coating film, it is preferable to use a resin that decomposes at a relatively low temperature and hardly remains in the film after the final baking. In terms of handling, a resin having low toxicity and safe (for example, polysaccharide) is preferable.

Examples of the water-soluble resin include cellulose derivatives (eg, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose), protein (eg, casein, sodium caseinate, ammonium caseinate), and alginic acid (eg, sodium alginate). ), Polyvinyl (polyvinyl alcohol, polyvinylpyrrolidone, etc.), polyacrylic acid (polyacrylic acid, sodium polyacrylate, etc.), polyether (polyether dialkyl ester, polyether dialkyl ether, modified polyether urethane, polyether) Ether-epoxy modified products), and maleic anhydride copolymers (such as partial esters of vinyl methyl ether-maleic anhydride copolymers).

Examples of resins that can be used in the non-aqueous coating liquid include ethyl cellulose, polyalkyl acrylate, polyalkyl vinyl ether, dimethyl polysiloxane, methyl phenyl polysiloxane, and organic modified polysiloxane (for example, modified silicone oil). And the like. Particularly, the cellulose derivative is widely used because it has various water-soluble and water-insoluble properties, and it is preferably used because it is easily decomposed by firing at 400 ° C. or lower, and is safe without toxicity.

The amount of the resin to be added may be appropriately selected according to the coating method, the drying and baking steps of the coating film, and the physical properties of the finally obtained film, and is not particularly limited. When the resin remains in the film after baking, it becomes a film-forming component.On the other hand, when the amount of the resin remaining in the film is excessive, the physical properties of the film tend to deteriorate. , The weight ratio of the metal salt to the total amount of all metals and Si is 0.001 to 0.001.
8.00, preferably 0.01 to 3.0.
It is preferably 0.

From the viewpoint of suppressing the appearance defects of the coating film, various surfactants used as paint additives can be added. In particular,
Some surfactants such as silicone-based and fluorine-based surfactants are effective in suppressing film thickness unevenness. In the present coating liquid, inorganic additives such as silicate, colloidal silica, and colloidal alumina can also be added.

In the present invention, the present coating solution is applied onto a substrate,
Provided is a method for forming an oxide film, which is fired at a temperature of 00 ° C. or more. At a temperature lower than 300 ° C., decomposition does not easily proceed. There is no particular upper limit on the temperature, and heating can be performed up to the heat-resistant temperature of the substrate, for example, about 650 to 700 ° C. in the case of ordinary soda lime glass. The higher the temperature, the more dense the oxide film.

The thickness (geometric thickness) of the oxide film in the present invention is not particularly limited, but is preferably from 20 to 500 nm, particularly preferably from 50 to 500 nm, from the viewpoint of design and practical durability. 400 nm is preferred. The desired visible light transmittance can be achieved by adjusting the film thickness.

When a film containing a Si oxide is formed on a glass substrate, the glass substrate is likely to be warped due to shrinkage of the film when heated at a high temperature. However, in the present invention, such a problem hardly occurs. This is because the present coating solution contains a metal salt, and as a result, the coefficient of thermal expansion of the resulting film becomes equal to or rather large than that of glass, and even when a thick film is formed, the glass substrate is less likely to warp during high-temperature firing. Conceivable.

Further, the present coating solution is further applied on an oxide film (lower film) formed by applying and heating the present coating solution on a substrate, so that the coating solution is contained in the pores of the lower film. Penetrate. By heating to a temperature of 300 ° C. or higher after the application, a denser and more durable multilayer oxide film can be obtained. The multi-layer oxide film may be formed into a multi-layer film by using a coating solution having the same composition, or may be formed into a multi-layer film using a coating solution having a different composition.

For the purpose of imparting a light-shielding property to a transparent substrate (for example, a glass substrate), it is possible to reduce the transmittance to a target value in one layer and to heat the thinner film in a thinner layer than in one layer.
Since it can be thermally decomposed, a denser film can be obtained. Moreover,
The coating solution penetrates into the pores of the porous film generated by the first layer thermal decomposition, and a denser and more durable film is obtained.

In the case of a multilayer, the total thickness of the oxide film is
Although not particularly limited, from the viewpoint of practical durability, 20
６００600 nm, particularly preferably 50-500 nm.
nm is preferred. In the case of a multilayer film, the thickness of each layer is not particularly limited, and can be formed to a desired thickness. When the second layer is formed thin (for example, about 100 nm or less), the denseness of the surface of the film is increased, and the durability against abrasion and the like is improved. Conversely, a film configuration in which the first layer is formed thin to increase the adhesion between the base and the second layer is also effective.

The method of applying the coating solution to the substrate is not particularly limited, and may be spin coating, dip coating, spray coating,
Meniscus coat, flow coat, transfer printing, screen printing and the like can be mentioned.

The present invention also provides a substrate with an oxide film formed by forming an oxide film on the substrate by the above-described method for forming an oxide film. The substrate preferably has heat resistance of 300 ° C. or higher, and examples thereof include a glass substrate and a ceramic substrate.

The present invention is suitable for forming an oxide film on an automobile window glass (especially, an ascending and descending automobile window glass) by the above-described oxide film forming method to obtain an automobile window glass with an oxide film. .

[0044]

EXAMPLES The details of the present invention will be described below with reference to Examples (Examples 1 to 9 and 1).
2 to 15) and Comparative Examples (Examples 10, 11, and 16), but the present invention is not limited thereto.

The substrate used in Examples 1 to 11 was a 4 mm-thick green heat ray absorbing glass substrate (100 mm × 100 mm in size, visible light transmittance of 7 mm) manufactured by a float method.
9% and a visible light reflectance of 8%).

The raw materials were mixed at the ratios shown in Table 1 (type and amount of metal source (unit: g), type and amount of oligomer (unit: g) and solvent), and the mixture was stirred at 50 ° C. for 2 hours and coated. Liquid. The abbreviations used in Table 1 are shown in Table 3. Si
Metal sources other than OR are nitrates. The molar ratio of Cr to the total amount of all metal and Si in the metal salt in the coating solution (C /
M), the molar ratio of Si to the total amount of metal and Si in the coating solution (S / M), the molar ratio of oligomer to the total amount of metal and Si in the coating solution (EG /
Table 1 also shows M), the type of resin, and the weight ratio (P / W) of the resin to the total amount of all metals and Si in the metal salt in the coating solution.

In Examples 1 to 7, 10 and 11, the substrate was coated with a spin coater and then baked to obtain a reflectance of 10%.
The following samples were obtained. In Examples 8 and 9, as in Example 1,
The lower layer liquid is applied to the substrate using a spin coater,
After baking at 0 ° C. for 2 minutes to form a lower layer, an upper layer liquid was applied using a spin coater and fired to form an upper layer, thereby obtaining a sample having a reflectance of 10% or less.

In Example 12, the substrate was formed of a 4 mm-thick green heat ray absorbing glass (1 m × 2 m, visible light transmittance 79%, visible light reflectance 8%) manufactured by a float method. Using a window glass used for a side door of an automobile, a coating solution shown in Table 1 was applied by flexographic printing, and then fired under the conditions shown in Table 2 to form a film.

In Example 13, the coating liquid shown in Table 1 was applied by using a dip coating method instead of the flexographic printing method in Example 12, and baked under the conditions shown in Table 2, in the same manner as in Example 12. went.

In Examples 14, 15, and 16, the coating liquids shown in Table 1 were applied by using a die coating method instead of the flexographic printing method in Example 12, and baked under the conditions shown in Table 2. The same was done. In addition, for the purpose of improving the appearance, a mixed solvent is used as the solvent, and the weight ratio is
For Examples 14 and 16, HG / PGM / MIBK / M
EK = 12/53/14/21; for Example 15, H
G / IPA / PGMAC = 25/55/20.

The firing conditions and film thickness (total film thickness in the case of multilayer) of the outermost oxide film, and the visible light transmittance T _{v of the} obtained sample
(JIS-R3106), transmission color and abrasion resistance are shown in Table 2. The abrasion resistance was the result of a change in haze value ΔH (%) after a Taber abrasion test (JIS-R3212) with a load of 500 gf and 1000 rotations. Note that ΔH required for practical use is 5.0% or less.

It was confirmed that the automotive side door glass with an oxide film obtained in Examples 12 to 16 had sufficient abrasion resistance for practical use. An oxide film having good appearance and almost no unevenness was obtained. However, in Example 16, there were many pinholes, and it was hard to say that the appearance was practically sufficient.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

According to the coating liquid for forming an oxide film of the present invention, it is possible to easily form a transition metal oxide film having extremely high abrasion resistance and little appearance defects. In addition, high-design glass that can be used for automobile door glass or the like that requires high wear resistance can be produced with good productivity and at low cost.

Continued on the front page F term (reference) 4G059 AA01 AC08 EA01 EA05 EB07 FA05 FA28 FA29 FB05 4J038 AA011 AA012 DL021 DL051 EA011 HA331 HA332 HA441 HA442 JA27 JC32 NA01 NA11 PA19

Claims (9)

[Claims] 1. Co, Cr, Mn, Fe, Ni, Cu, Z
a coating solution containing at least one metal salt selected from the group consisting of n and lanthanoids (La to Lu), an alkoxide of Si or a partial hydrolyzate thereof, and a resin, wherein the metal in the coating solution is The coating liquid for forming an oxide film, wherein the atomic ratio of Si to the total amount of all metals and Si of the salt is 0.28 or more. 2. The coating solution for forming an oxide film according to claim 1, wherein the metal salt comprises a Cu salt and a Mn salt. 3. The method according to claim 1, wherein the metal salt is a nitrate.
3. The coating solution for forming an oxide film according to item 1. 4. The oxidation according to claim 1, comprising at least one ethylene glycol oligomer represented by the chemical formula HO (CH ₂ CH ₂ O) _n H (where n is an integer of 2 to 8). Coating solution for material film formation. 5. The coating liquid for forming an oxide film according to claim 4, wherein the ethylene glycol oligomer is at least one selected from the group consisting of diethylene glycol, triethylene glycol and tetraethylene glycol. 6. The coating solution for forming an oxide film according to claim 4, wherein the molar ratio of the ethylene glycol oligomer to all metals of the metal salt in the coating solution is 0.3 or less. 7. The coating liquid for forming an oxide film according to claim 1, wherein the resin is a water-soluble resin. 8. A method for forming an oxide film, comprising applying the coating solution for forming an oxide film according to claim 1 on a substrate and firing at a temperature of 300 ° C. or higher. 9. A substrate with an oxide film, wherein an oxide film is formed on the substrate by the method for forming an oxide film according to claim 8.