JPS5936955B2 - Titanium oxide film formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a uniform, dense, transparent continuous titanium oxide film on the surface of a substrate, and more specifically, the present invention relates to a method for forming a uniform, dense, transparent, continuous titanium oxide film on the surface of a substrate. The present invention relates to a method of forming a titanium oxide film, which is characterized by coating the titanium oxide film.

Forming a titanium oxide film on the surface of substrates such as glass, metals, and ceramics is not only effective as a method of imparting corrosion resistance, insulation, and high surface hardness to substrates, but also as a method for providing optical and electronic materials. This is an effective means for adding functionality. In particular, by forming a transparent titanium dioxide coating on the inner surface of a glass tube for high-output fluorescent lamps, which has a higher refractive index for ultraviolet rays than glass, it prevents contact between the glass tube surface, which is rich in alkali metals, and the phosphor film. This prevents deterioration of the phosphor, and since the refractive index of the titanium dioxide film is higher than that of the base glass, UV rays are reflected inside the lamp, increasing the efficiency of UV rays and reducing the rate of UV rays reaching the glass tube. By doing so, it is possible to prevent the glass from being colored by ultraviolet irradiation and reduce luminous flux deterioration. Tetler n is an organic titanium used to form a titanium oxide film by coating an organic titanium compound.
Titanate ester compounds represented by the general formula (wherein R is a hydrocarbon group) such as butyl titanate and tetraisopropyl titanate are commonly used; This causes problems such as the coating film becoming cloudy due to absorption of water, and the coated film undergoing rapid hydrolysis due to moisture in the atmosphere, producing particulate titanium dioxide and becoming opaque.

Therefore, a method using organic titanium compounds that are less likely to cause hydrolysis has been proposed (Japanese Patent Application Laid-Open No. 122519-1989).
Public Law No. 49-122520). These patents describe a method of applying an organic titanium solution represented by the general formula (wherein R is a hydrocarbon group) using an alcohol having 5 to 9 carbon atoms or an acetate ester of the alcohol as a solvent, and A method of applying titanate has been proposed.

In the former method, hydrolysis resistance is improved to some extent by producing a titanate ester having an alkyl group with a large number of carbon atoms through the transesterification reaction, but the decomposition shrinkage rate when the film decomposes into titanium dioxide is high. This may cause cracks to occur in the coating.

In addition, in either method, the hydrolysis resistance of these solutions is not sufficient, and when the solutions are handled in the atmosphere, they become cloudy. The inventors of the present invention have conducted intensive research in order to find an organic titanium compound that can be handled stably in the atmosphere and that can form a transparent and dense film, and as a result, they have found that a solution of a polytitanoxane chelate compound is extremely effective. They discovered this and completed the present invention.

To explain the present invention in more detail, a substrate such as glass, metal, or ceramics is coated with a structural unit having a general formula (wherein, (2 or more types), general formula (in the formula, X is 12 carbon atoms forming a chelate ring with titanium)
One or more of the following organic compound residues, Y is one or more of the following hydrocarbon compound residues having 10 or less carbon atoms, alkoxy groups, or carboxylic acid residues), and general formulas (wherein, Y is consisting of one or more types of hydrocarbon compound residues, alkoxy groups, or carboxylic acid residues having 10 or less carbon atoms, and the molar ratio of X and Y is 1≧IXl/0
A titanium oxide film forming method characterized by applying a solution of a polytitanoxane chelate compound in which It can be handled stably with
Moreover, the formed film can be a uniform, dense, and transparent titanium oxide film.

The polytitanoxane chelate compound has the general formula (wherein Y
is a general formula (In the formula, X is one or more organic substituents that form a chelate ring with titanium.) It can be produced by reacting a chelate-forming compound represented by, for example, according to formula (1). Since the reaction easily proceeds at room temperature, it can be produced by simply mixing the chelate-forming compound with a solution of a polytitanoxane compound having a structural unit represented by the general formula dissolved in an organic solvent, and the reaction solution can be used as it is or If necessary, it can be further diluted with a suitable organic solvent and used as a coating solution for film formation.

Here, 2≧j>0.5, k+l+m=I, l≧( 2
k+l)/2(k+l+m)≧0.2.

In addition, as another production method, the general formula (where n = 0, 1 or 2, X is 12 carbon atoms forming a chelate ring with titanium)
In a solution of one or more organic titanium compounds represented by one or more of the following organic compound residues (Y is a hydrocarbon compound residue having 10 or less carbon atoms, an alkoxy group, or a carboxylic acid residue), It can be produced, for example, by adding approximately the same molar amount (80 to 130 m01e%) of water to the organic titanium compound, for example, according to formula (2).

Chelate-forming compounds represented by the general formula
Ketone acids, esters of the ketone acids such as methyl, ethyl, n-propyl, IsO-propyl, n-butyl, IsO-butyl, tert-butyl, glycolic acid,
Esters such as methyl, ethyl, n-propyl, IsO-propyl, n-butyl, tert-butyl, etc. of α- or β-oxyacids such as lactic acid, α-oxybutyric acid, hydroacrylic acid, and salicylic acid; α- or β-oxyketones such as diacetone alcohol and acetoin, α- or β-oxyaldehydes such as glycolaldehyde and aldol, α-amino acids such as glycine and alanine, and α- such as aminoethyl alcohol.
Alternatively, all compounds capable of forming a chelate ring with titanium, including β-amino alcohols, etc., can be used alone or as a mixture of two or more, and polytitanoxane chelate compounds produced using these compounds. Acetylacetone, ethyl acetoacetate,
Diacetone alcohol and the like are particularly preferred. The substrate to which the film forming method according to the present invention can be applied may be any material such as glass, metal, ceramics, etc., as long as it can withstand the heat treatment temperature during film formation.

The film forming method consists of a coating process of the polytitanoxane chelate compound solution and a film forming process by decomposing the polytitanoxane chelate compound, and existing coating methods such as dipping, spraying, and casting are used as the coating method. The titanium oxide film formed by decomposition can be achieved by heat treatment at 400°C or higher and 1400°C or lower, or by heat treatment at 490°C or higher after hydrolysis with atmospheric moisture, steam, or water. .

Alternatively, it is also possible to use a method in which the polytitanoxane chelate compound solution is applied to the surface of a substrate heated to 400° C. or higher, and simultaneously thermally decomposed on the substrate surface to form a titanium oxide film. As the solvent for the polytitanoxane chelate compound solution for coating, any organic solvent that is also used in the production of the polytitanoxane chelate compound can be used. However, for ease of solvent removal after coating, boiling point Organic solvents having a temperature of 180° C. or lower, particularly lower alcohols having 8 or less carbon atoms, ethers, ketones, aliphatic hydrocarbons, aromatic hydrocarbons, and halides thereof are preferred.

The concentration of the polytitanoxane chelate compound in the polytitanoxane chelate compound solution for coating is 7.5 wt%.
Any value below can be selected, but a film formed with a highly concentrated solution has the disadvantage that it becomes too thick and cracks are likely to occur. It is preferable to use it within the range of . In order to form a thick film without cracks, a film having an arbitrary thickness can be obtained by repeating the film forming process and overcoating. The present invention will be explained below with reference to Examples.

Example 1 An equivalent amount of acetylacetone was added to an n-butanol solution of polytitanoxane, whose structural unit is represented by the formula (the average value of n is 11.2), obtained by reacting tetra-n-butyl titanate with the same mole of water. Concentration 1 of a polytitanoxane chelate compound whose structural unit is represented by the formula (k=m)
A 0% by weight n-butanol solution was prepared.

For comparison, a 10% by weight n-butanol solution of tetra-n-butyl titanate and a 10% by weight n-butanol solution of polytitanoxane whose structural unit is represented by the formula (the average value of n is 11.2) were prepared. did.

50 d of each of these bath liquids was heated to an inner diameter of 40 m 1 L at room temperature and in the atmosphere.
When stored in a glass weighing bottle with a lid of S depth 70 mm, the solution of tetra-n-butyl titanate and the solution of a polytitanoxane compound having an n-butoxy group became cloudy on the 13th and 14th day after preparation, respectively. However, the solution of the polytitanoxane chelate compound remained a clear solution with a yellowish tinge even after 3 months had passed.

Using these solutions, a titanium dioxide film was formed on a 40 x 60 x 111 glass plate.

First, a glass plate was immersed in the solution, then slowly pulled up so as not to create flow marks, left in air at room temperature for 1 hour, and then heated in air at 100 °C/C.
The temperature was raised to 500°C at a temperature increase rate of 1 hour, and fired at 500°C for 1 hour. The surface condition of the coating was the best when the polytitanoxane chelate compound solution was used, with no cracks at all, but cracks occurred partially when the other two solutions were used. The film composition was determined to be TiO2 in each case by ESCA measurement, and the film thickness was approximately 2000 nm by electron microscopic observation.
Example 2 A tetrahydrofuran solution having a concentration of 4.8% by weight of a polytitanoxane chelate compound whose structural unit is represented by the formula was prepared.

This solution was yellow and transparent, but when stored in air at room temperature, no change was observed even after 6 months had passed. The solution was applied to a glass plate and fired in the same manner as in Example 1 to form a TlO2 film.

Claims (1)

[Claims] 1. The base material has a structural unit having a general formula ▲a mathematical formula, a chemical formula, a table, etc.▼ (wherein,
One or more of the following organic compound residues), general formula ▲ mathematical formula, chemical formula, table, etc. ▼ (wherein, X is the number of carbon atoms 12 forming a chelate ring with titanium
One or more of the following organic compound residues, Y is one or more of the following hydrocarbon compound residues, alkoxy groups, or carboxylic acid residues) and general formulas ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (In the formula, Y consists of one or more types of hydrocarbon compound residues, alkoxy groups, or carboxylic acid residues having 10 or less carbon atoms), and the molar ratio of X and Y is 1≧[X ]/(
A method for forming a titanium oxide film, comprising applying a solution of a polytitanoxane chelate compound in which [X]+[Y]≧0.2.