JPS6311300B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates generally to pyrolytic deposition techniques for metal oxide coatings, and more particularly to pyrolytic deposition of metal oxide coatings from aqueous solutions of coating reactants. Pyrolytic deposition of metal oxides on glass surfaces is described in US Pat. No. 3,660,061. The organometallic salt, preferably acetylacetonate, is dissolved in an organic vehicle such as methylene chloride. Other suitable solvents include aliphatic and olefinic halocarbons, halogenated hydrocarbons, alcohols and nonpolar aromatic compounds such as benzene and toluene. The organic solution is sprayed onto the hot glass surface where it pyrolyzes to produce a metal oxide film that alters the solar energy reflectance and transmittance of the glass. US Pat. No. 3,411,934 discloses that cobalt oxide is particularly suitable for use as a coating on glass due to its good solar protection properties. However, cobalt oxide coatings are not as uniform or adherent as desired. The patent states that the adhesion, durability, and optical properties of the cobalt oxide coating can be improved by applying a thin tin oxide undercoating to the glass surface and then coating the glass surface with cobalt oxide by thermal decomposition of a cobalt compound such as cobalt acetylacetonate. It is taught that this can be improved by
Preferably, the cobalt oxide coating also contains oxides of iron and chromium. If anything,
These oxides improve the drag resistance of the coating without reducing the solar protection properties of the cobalt oxide. Preferred solvent systems for the metal coating reactants include polar organic compounds and non-polar aromatic compounds, particularly methanol in combination with benzene or toluene. Modern concerns in eliminating the health and environmental hazards of using large amounts of organic solvents have encouraged the development of aqueous coating compositions. US Pat.
It is known from specification No. 2688565. However, such coatings have a particulate, irregular texture and are highly porous, resulting in low acid resistance evidenced by peeling of the coating. The present invention involves the pyrolytic deposition of spinel-type coatings containing cobalt oxide and tin oxide by pyrolysis of aqueous solutions of water-soluble cobalt salts and water-soluble tin compounds. The resulting coating is more uniform in appearance and less porous than a cobalt oxide coating that does not contain tin oxide. Also, due to the fact that cobalt/tin oxide coatings withstand immersion in 0.5% hydrofluoric acid solution for 8 minutes without peeling of the coating, whereas cobalt oxide coatings fail this durability test. Greater durability as proven. Dissolve the cobalt and tin coating reactants in water. This aqueous solution is then applied to the glass surface at a temperature high enough to pyrolyze the coating reactants and form a metal oxide film. Aqueous solutions of water-soluble cobalt salts, preferably cobalt acetate, and water-soluble tin compounds, preferably dimethyltin dichloride, are prepared over a wide range of cobalt to tin ratios. The weight ratio of cobalt to tin is approximately 2:1~
Preferably it is 20:1, more preferably about 5:1 to 12:1. The total metal concentration of the solution is approximately 1
Preferably it is ~12% by weight, more preferably about 5-6% by weight. Preferred cobalt salts include cobalt nitrate and perchlorate and cobalt acetate. Preferred water-soluble tin compounds include tin chlorides such as SnCl ₂ and SnCl ₄ and other alkyltin chlorides such as methyltin trichloride, trimethyltin chloride, diethyltin dichloride, diisopropyltin dichloride, bisacetylacetone stannic bisacetylacetone dichloride) and stannic acetate. The aqueous solution of cobalt and tin coating reactants is heated to a temperature sufficient to thermally decompose the coating reactants to form an oxide film, preferably at least about 500°C, more preferably at least about 1000°C.
It is applied to the surface of a glass substrate maintained at 1200°C (approximately 538-650°C). In a particularly preferred embodiment of the invention, a stock solution of cobalt acetate containing 5.0% by weight of cobalt is
It is prepared by dissolving cobalt acetate in water, preferably containing about 5% by weight glacial acetic acid to provide a long shelf life. The selected hydrolyzable tin compound is separately dissolved in water. Coating solutions with different cobalt/tin ratios are prepared by mixing these two solutions in different proportions. A particularly preferred method of applying the solution to a hot glass surface is to remove the solution formed on the metal bath after the continuous glass ribbon is raised from the molten metal bath in a refractory tank and conveyed over a reducing atmosphere that protects the metal bath. The method is to spray the aqueous solution onto the surface of the ribbon. A detailed description of a preferred method of pyrolytically depositing metal oxide films on glass is found in US Pat. No. 3,660,061, which is incorporated herein by reference. The invention will be further understood by the following specific examples. The spectral properties of glasses coated according to those examples are shown in Table 1. In Table 1, the luminous transmittance is the ratio (percentage) of the luminous flux incident on an object to the luminous flux transmitted through the object, and the luminous reflectance is:
It is the ratio (percentage) of the luminous flux incident on an object to the luminous flux reflected from the object. In monochromatic display, chromaticity is generally displayed in terms of dominant wavelength and excitation purity. Stimulus purity is the saturation of a color expressed as a percentage. Example 1 21.13% by weight of cobalt acetate tetrahydrate Co
(C ₂ H ₃ O ₂ ) _{2.4H 2} O, 5.25% by weight glacial acetic acid and
A cobalt acetate stock solution is prepared by combining 73.62% by weight of water. This cobalt stock solution is 5.0
% cobalt by weight. A tin stock solution is prepared by dissolving 23.13% by weight of dimethyltin dichloride (CH ₃ ) ₂ SnCl ₂ in 76.87% by weight of water. This tin stock solution contains 12.5% tin by weight. A coating solution for depositing a cobalt/tin oxide spinel type coating is prepared by combining 100 parts by volume of a cobalt stock solution with 11.08 parts by volume of a tin stock solution. The cobalt to tin ratio is 3.5-1.0 and the total metal concentration is 5.85% by weight. Spray the coating solution onto the glass surface at 1050-1070㎓ (approximately 566-577℃). The coating reactant thermally decomposes to form a durable, uniform cobalt/tin oxide spinel-type film on the glass surface.

【table】

TABLE The above examples are provided to illustrate the invention.
Various modifications apparent to those skilled in the art are within the scope of the invention. Other water-soluble metal compounds can be used as well as proportions and concentrations of metals outside the range of the specific examples. Cobalt/tin oxide spinel type coatings can be deposited with other coatings and on a variety of substrates other than glass, especially non-metallic substrates such as ceramics and other refractory materials. The scope of the invention is defined by the claims.

Claims (1)

[Claims] 1. A method for depositing a spinel-type film containing oxides of cobalt and tin, characterized by comprising the following steps: a. Bringing a substrate to a temperature of 260°C (500°C) or higher in an oxidizing atmosphere; maintaining the substrate surface at the above temperature with a water-soluble cobalt salt selected from the group consisting of cobalt acetate, cobalt nitrate and cobalt perchlorate, and the group consisting of tin chloride, alkyltin chloride and tin acetate. An aqueous solution containing a water-soluble tin compound selected from the following, wherein the weight ratio of cobalt to tin is 2:1 to 20:
1, and the total metal concentration is 1 to 12% by weight of the aqueous solution.
A process of contacting with an aqueous solution. 2 a tin compound and cobalt acetate whose aqueous solution is selected from the group consisting of tin chloride and alkyltin chloride;
2. The method of claim 1, comprising a cobalt salt selected from the group consisting of cobalt nitrate and cobalt perchlorate. 3. The method of claim 2, wherein the aqueous solution comprises dimethyltin dichloride and cobalt acetate. 4. The method of claim 3, wherein the cobalt to tin ratio is between 5:1 and 12:1 and the total concentration of metals in the solution is between 5 and 6%. 5. The method of claim 3, wherein the substrate is a non-metallic refractory material. 6. The method according to claim 5, wherein the substrate is glass.