JPS6144948B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming titanium oxide from an alkyl titanate. More specifically, the present invention relates to a method for forming titanium oxide from an alkyl titanate. The present invention relates to a method for forming a film. Titanium oxide thin films are important components of transparent conductive coatings or selective light transmission coatings as high refractive dielectric layers. Conventionally, as a method for forming these titanium oxide thin film layers, for example, a vacuum evaporation method, a cathode sputtering method, etc. have been used. However, these methods have drawbacks such as difficulty in forming a thin film of uniform thickness and low productivity. In order to improve these drawbacks, attempts have been made to coat a solution containing an alkyl titanate and obtain a thin titanium oxide layer by heat treatment, etc. However, due to the poor stability of the alkyl titanate to water, It is difficult to obtain a uniform and transparent coating layer in the alkyl titanate coating process, and it is difficult to form a desired titanium oxide thin film. Therefore, attempts have been made to convert alkyl titanates into complex salts to obtain stable coating solutions in order to improve their instability with water and ease of handling. For example, there is a method of adding acetylacetone or ethyl acetoacetate to an alkyl titanate. Forming a complex salt of a titanium compound in this way can stabilize the coating solution and improve the operability of the coating itself, but the titanium oxide thin film formed by heat-treating the coating layer after coating is However, the organic compound used to form the complex salt and the alkyloxy component of the raw alkyl titanate remain, making it impossible to form a fully satisfactory titanium oxide thin film layer. The present invention relates to a method of coating an alkyl titanate to form a titanium oxide thin film, which is stable against moisture in the alkyl titanate coating process and quickly forming a titanium oxide thin film in the heat treatment process. After extensive research, we discovered a new method that meets these objectives. That is, the present invention provides a transparent titanium oxide film, which is characterized by treating an alkyl titanate or a solution thereof with an acid and then heating the same to cause solvent removal and/or crosslinking reaction to form a transparent titanium oxide film. This is a method for manufacturing a titanium film. The coating solution prepared by the method of the present invention is stable against moisture and can be easily coated in a uniform layer on the surfaces of glass plates, films, metal plates, etc. in air at room temperature. Furthermore, it has the characteristic that the desired titanium oxide thin film can be quickly formed by heating the coated substrate in, for example, a hot air dryer. Furthermore, by adjusting the concentration and amount of the coating liquid to be prepared, the thickness of the titanium oxide thin film produced can be easily controlled. The alkyl titanate used in the present invention has the general formula Ti _l O _n R _o (where R is an alkyl group, l,
m and n are positive integers). Among the alkyl titanates represented by the above general formula, those where m=3l+1, n=2l+2, and l=1 to 40 are preferably used from the viewpoint of ease of coating. The value of l may not be uniform but may have a distribution, but alkyl titanates having a distribution of l values with a maximum value of 25 or less are particularly preferred in coating operations. In the above general formula, R has 1 to 20 carbon atoms.
Preferably. In particular, those having an alkyl group having 2 to 15 carbon atoms are desirable from the viewpoint of film forming operations. When the alkyl titanate reacts with an acid, some or all of the titanium atoms become ionized titanium, and when applied to the surface of a molded object as a solution, most of the titanium is ionized through reactions such as hydrolysis and subsequent condensation reactions. It is thought that titanium oxide has a network structure. Examples of the alkyl titanate used in the present invention include tetrabutyl titanate, tetraethyl titanate, tetrapropyl titanate, tetrastearyl titanate, and condensates thereof. By using an acid-modified alkyl titanate solution as in the method of the present invention, it has become possible to stabilize the coating solution in the coating process and form a uniform and transparent coating film. In addition, a titanium oxide thin film is formed by applying heat treatment to the surface of the molded product described above, but the titanium oxide thin film from alkyl titanate treated with acid according to the present invention forms a sufficient network of titanium oxide, and It is characterized by very little organic matter originating from the titanate and the acid components used. The acids used in the present invention include inorganic acids and organic acids. Examples of inorganic acids include those that give H ⁺ when dissolved in water, such as hydrogen chloride (hydrochloric acid), hydrogen bromide (hydrobromic acid), sulfuric acid, phosphoric acid, phosphorous acid, metaphosphoric acid, polyphosphoric acid, and boron. acid, benzenesulfonic acid, etc. The organic acid has the general formula shown below. R(CO ₂ H) _o [However, in the formula, R represents an n-valent organic residue, and n
represents a positive number of 1 or more. ] Examples of such organic acids include formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, undecanoic acid, oleic acid, cyclohexanecarboxylic acid,
Examples include monochloroacetic acid, benzoic acid, oxalic acid, succinic acid, and adipic acid. Among these, particularly preferred are hydrochloric acid, formic acid, acetic acid, propionic acid, butyric acid, monochloroacetic acid and the like. The amount of acid used in the present invention is preferably such that the carboxyl group equivalent, expressed as an organic acid, is in the range of 0.1 to 4, particularly preferably in the range of 0.2 to 20, relative to the titanium atom of the alkyl titanate used. If the acid treatment is below the lower limit of this range, the effect of acid treatment is small, and if it exceeds the upper limit of this range, the coating solution often becomes cloudy or the titanium oxide film formed does not have a sufficient crosslinked (network) structure. . The solvent generally used in forming the film of the present invention is one that sufficiently dissolves the titanium compound for coating, has an affinity for the surface of the molded object to be coated, is easy to coat, and is suitable for use after coating. A solvent that dries easily is preferred. Such solvents include hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene, xylene,
Methanol, ethanol, isopropyl alcohol, propyl alcohol, butanol, cyclohexanol, tetrahydrofuran, dioxane,
Examples include acetone, ethyl acetate, butyl acetate, chloroform, methyl cellosolve, and the like. These solvents may be used alone or in combination of two or more. The preparation after coating in the present invention is carried out by dissolving the alkyl titanate in a suitable solvent and reacting it with a predetermined proportion of acid. At this time, the concentration of the applied titanium solution can be changed depending on the thickness of the finally formed titanium oxide thin film, the application method, the molded object to be applied, etc. For example, in order to uniformly provide a titanium oxide thin film layer with a thickness of several hundred angstroms or less, the concentration is particularly preferably adjusted to 1 to 7.5% by weight. When applying this solution to the surface of a molded article, for example, a dipping method, a spraying method, a method using a coating machine, etc. are used. The desired titanium oxide thin film layer can be obtained by heat-treating the solution at the same time or after coating. This heat treatment is performed at a temperature of 50 to 220°C for about 10 seconds to 1 hour. The effects of forming a titanium oxide thin film by the method of the present invention are as follows. 1. The coated titanium solution became stable against moisture and had a longer pot life. 2. As a result of the coating liquid becoming more stable, strict control during the coating process is no longer necessary. 3. The titanium oxide thin film formed has a highly transparent network structure with good performance. Examples will be described below. Examples 1 to 4 A 3.0% by weight solution of the alkyl titanate was prepared using the following T ₄ or T ₁₀ alkyl titanate and the solvent shown in the table below. A specified acid shown in the table below was added to this and reacted to obtain an acid-treated alkyl titanate coating solution. This was coated on a polyethylene terephthalate film with a light transmittance of 86% and a thickness of 75 μm using a bar coater to a thickness of several microns, and then heated for 2 minutes in a hot air dryer at 130°C to form a titanium oxide thin film. Ta. The results obtained are also shown in the table below. In addition, Pr in the same table represents a prokyl group. [However, Bu represents a butyl group. 〕 【table】

Claims (1)

[Claims] 1. A method for forming a transparent titanium oxide film by removing the solvent and/or causing a crosslinking reaction from an alkyl titanate or a solution thereof by heat treatment, wherein the alkyl titanate or a solution thereof is heated before the heat treatment. A method for producing a transparent titanium oxide film, characterized in that it is treated with an acid. 2. The manufacturing method according to claim 1, wherein the acid is an organic acid having 20 or less carbon atoms. 3. Claim 1, wherein the acid is at least one inorganic acid selected from hydrogen chloride (hydrochloric acid), hydrobromic acid, sulfuric acid, phosphorous acid, metaphosphoric acid, polyphosphoric acid, and boric acid. manufacturing method.