JPS6339670B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention uses group A metals (Ti, Ti, etc.) on a substrate such as glass.
This invention relates to a composition that forms a transparent thin film of oxides of Zr, Hf). Titanium oxide thin films are valuable components of transparent conductive coatings or permselective coatings as high refractive index dielectric layers. Zirconium oxide thin films are also used for correcting chromatic aberration in camera lenses and preventing diffused reflection in eyeglass lenses. Hafnium oxide thin films can also be used in the same way as zirconium oxide. Traditionally, these thin films have been formed by, for example, vacuum evaporation,
This is carried out by sputtering, CVD, etc., but these methods have poor raw material utilization, expensive equipment, and are unsatisfactory as production technology, so they are not suitable for mass production with simple equipment. ,
Various methods have been attempted in which a solution of a group A metal compound is applied to a substrate by dipping or coating, and the solution is heated to convert it into an oxide. Organic solvent solutions of metal alkoxides have been proposed as coating liquids, but alkoxides are strongly hydrolyzable and have a short shelf life, such as precipitation due to moisture absorption, or poor operability and film formation. There were drawbacks such as precipitation, etc. occurring during liquid application, making it impossible to form a uniform film. To improve this, attempts have been made to convert alkoxides into complex salts to obtain stable solutions. For example, acetylacetone is added to titanium alkoxide. Although this coating solution has improved stability against water and operability, it has the disadvantage that pot-shaped crystals of metal acetylacetone salt remain in the film obtained by heat treatment after coating. It also has the disadvantage that it has low solubility in alcohols and the like, making it impossible to form thick films. A hydroalcoholic solution of a β-diketone complex of a group A metal is stable without deterioration due to moisture absorption during the coating process for forming a transparent film of a group A metal oxide, and can increase the concentration of the metal complex in the coating solution. In the heat treatment step, a group A metal oxide transparent film is quickly formed. Although the β-diketone complex of Group A metal has low solubility in alcohol, the present inventors have found that the solubility increases by introducing water into this system. β-diketone complexes are well known as chelate compounds. The present inventors have discovered that β-
We prepared a coating solution for forming an oxide film of the metal using a diketone complex, and conducted intensive research to increase the concentration in the coating solution and form an excellent transparent oxide film, but the results were not always satisfactory. I wasn't getting it. However, I happened to get good results, so
When the cause was investigated, it was discovered that the alcohol used contained a considerable amount of water. This was a surprising experience for the inventors, as it was generally believed that β-diketone complexes are also easily hydrolyzed and should not be exposed to water. Using this as a starting point, we continued our research and found that β-diketone complexes have low solubility in alcohol, but the solubility increases when water is added, and that they are surprisingly stable against hydrolysis. . The present invention is based on these findings. According to the present invention, a transparent oxide film of a group A metal is obtained by dissolving a β-diketone complex of the metal in a mixture of water and a saturated monovalent alkanol having 4 or less carbon atoms containing 0.5 to 45% by weight of water. A forming composition is provided. I am not aware of any example in which a β-diketone complex has been dissolved in water or an aqueous alcohol. The β-diketone complexes of Group A metals used in the present invention include acetylacetone complexes, benzoylacetone complexes (benzoyltrifluoroacetone complexes, trifluoroacetylacetone complexes, dibenzoylmethane complexes), and the like. The coating liquid of the present invention is obtained by mixing this complex with alcohol and water. The mixture may be mixed in any order. Alcohols used in the present invention include methyl, ethyl,
It is a saturated monohydric alkanol having up to 4 carbon atoms that is compatible with water, such as propyl and butyl alcohol. This can be used alone or as a mixture of these.
The weight concentration of water in the alcohol ranges from 0.5 to 45%, preferably from 1 to 40%, more preferably from 15 to 35%. Otherwise, a healthy membrane cannot be formed. Further, the concentration of this complex is determined depending on the desired film thickness. The coating liquid thus obtained has a long shelf life. This coating liquid was put into a reagent bottle, and no change occurred even after it was left for 6 months. Under similar conditions, precipitation occurred in metal alkoxide solutions. The coating solution can be applied to a substrate such as glass by dipping, spray spinner, brushing, etc., but dipping is preferred. Next, the method for drying the solvent is to leave it in the air and then forcefully heat it (50°C to 150°C) (for example, leave it in the air for 30 minutes,
Dry at 100°C for approximately 15 minutes). However, the drying time is not limited. Next, the coated material is baked together with the substrate at 300° C. to 600° C. in an air atmosphere or an oxygen atmosphere to bake the oxide, thereby obtaining a transparent film of the Group A metal oxide. At temperatures below 300°C, acetylacetone, etc. remain, making it difficult to obtain a complete oxide film. The baking time may be about 10 seconds to 1 hour, depending on the coating thickness and baking temperature. The base material (substrate) for film formation of the composition of the present invention may be soda lime glass, borosilicate glass, quartz glass, quartz, alumina, various optical glasses, etc., which have wettability to the composition and which are suitable for forming a coating film. There is no particular limitation as long as it can withstand the oxidation firing temperature. Next, the present invention will be specifically explained using experimental examples and examples. FIG. 1 is a diagram showing the relationship between the composition and solubility of acetylacetone-Zr salt in an isopropyl alcohol-water binary solvent. A similar tendency was observed for acetylacetone salts of Ti and Hf.
It was also found that water not only increases solubility but also suppresses the precipitation of coarse bowl-shaped crystals of acetylacetone salt during film formation. Examples 1 to 6 Acetylacetone salt of Zr using a 200ml beaker
Zr(C ₅ H ₇ O ₂ ) ₄ was dissolved in 100 ml of a mixture of isopropyl alcohol and distilled water shown in Table 1 to prepare a coating solution. As shown in Table 1, the weight concentration of Zr acetylacetone salt was changed to 2, 4, 6, 8, and 10%. A 25 x 75 mm soda lime glass plate with a well-washed surface was immersed in this coating solution, pulled out, left in the air for 30 minutes, dried at 100℃ for 15 minutes, and then heated at 500℃ for 30 minutes. A zirconium oxide film was formed on the surface. The properties of the films formed are shown in Table 1 using symbols. Examples 7-12 Acetylacetone salt of Ti using a 200ml beaker
TiO(C ₅ H ₇ O ₂ ) ₂ was dissolved in 100 ml of a mixture of ethyl alcohol and distilled water shown in Table 1 to prepare a coating solution. The weight concentration of acetylacetone salt of Ti is
As shown in Table 1, it was changed to 2, 4, 6, 8, and 10%. The same operations as in Example 1 were carried out, and as a result, a titanium oxide film was formed on the surface of the glass plate. The properties of the films formed are shown in Table 1 using symbols. Examples 13-18 The acetylacetone salt of Hf (C ₅ H ₇ O ₂ ) ₄ is shown in Table 1.
A coating solution was prepared by dissolving it in 100 ml of the mixture of isopropyl alcohol and distilled water shown in , using a 200 ml beaker. The weight concentration of Hf acetylacetone salt was changed to 2, 4, 6, 8, and 10% as shown in Table 1.

[Table] As a result of performing the same operations as in Example 1, a colorless and transparent hafnium oxide film was formed on the surface of the glass plate. The properties of the formed film are shown in Table 1.
It is indicated with a symbol inside. Examples 19-22 Using a 200 ml beaker, dissolve the benzoylacetone salt of Zr (C ₁₀ H ₉ O ₂ ) ₄ in 100 ml of the mixture of isopropyl alcohol and distilled water shown in Table 1 to prepare a coating solution. did. As shown in Table 1, the weight concentrations of Zr benzoylacetone salt are 2, 4, 6,
It was changed to 8.10%. The same operations as in Example 1 were then carried out, and as a result, a zirconium oxide film was formed on the surface of the glass plate. The properties of the films formed are shown in Table 1 using symbols. As described above, by using a solvent prepared by adding water to a lower saturated monovalent alkanol, a coating liquid with excellent stability and thin film forming properties for forming a group A metal oxide thin film can be obtained.

[Brief explanation of the drawing]

The attached drawing is a graph showing the relationship between the water content and the solubility of Zr acetylacetone salt in an isopropyl alcohol-water binary system.

Claims (1)

[Scope of Claims] 1. A transparent oxide of a group A metal obtained by dissolving a β-diketone complex of the metal in a mixture of water and a saturated monovalent alkanol having 4 or less carbon atoms containing 0.5 to 45% by weight of water. Composition for film formation. 2. The composition according to claim 1, wherein the amount of water in the alkanol-water mixture is 1 to 1.
A composition that is 40% by weight. 3. The composition according to claim 2, wherein the amount of water in the alkanol-water mixture is from 15 to
A composition that is 35% by weight. 4. A composition according to any one of claims 1 to 2, wherein β of a group A metal is
- A composition in which the diketone complex is selected from acetylacetone complexes, benzoylacetone complexes, benzoylfluoroacetone complexes, trifluoroacetylacetone complexes, and dibenzoylmethane complexes of Ti, Zr, and Hf.