JPS6058308B2 - Method for manufacturing titanium oxide film - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a titanium oxide film.

Transparent titanium oxide thin films are used as high refractive index dielectric thin films in various applications, such as as a component of transparent conductive coatings or selective light transmitting coatings. Conventionally, these titanium oxide thin films have been formed by physical means such as vacuum evaporation and cathode sputtering.

However, these methods have drawbacks such as difficulty in forming a thin film of uniform thickness and low productivity.
In an attempt to improve these drawbacks, a method has been proposed in which a solution containing an alkyl titanate is applied, hydrolyzed and condensed to form a titanium oxide thin film.
Due to the poor stability of alkyl titanates against water and moisture, it is difficult to obtain a uniform and transparent coating layer during the coating process of alkyl titanate solutions.For this reason, a coating process that strictly controls moisture during the process is adopted. However, problems still occur frequently, and it is currently extremely difficult to form the desired robust titanium oxide thin film.

In view of this situation, the inventor of the present invention conducted intensive research on the formation of a titanium oxide thin film layer that is not affected by moisture, and found that unnecessary hydrolysis due to moisture could be prevented by reducing the electron density on titanium atoms. After conducting research based on the hypothesis, it was found that the stability of alkyl titanate compounds against moisture is improved by arranging an atom and/or group with higher electronegativity than an alkoxy group on the titanium atom of the alkyl titanate compound. They discovered this and arrived at the present invention.

That is, the present invention provides the following general formula [I] Z1, Ti-~0]ji-R...[I](OR
)m[However, in the formula, It is an atom or group with higher electronegativity than OR, l and m are 0 or 2 and satisfy 1+m=2, and n is an integer of 1 to 30.

Further, a method for producing a titanium oxide film, characterized in that the titanium compound represented by n l (5 m satisfies Σl/Σm = 0.1 to 2.5) is formed by heat treatment. It is.

The titanium compound represented by the above general formula [1] will be explained in more detail. As described above, X is an atom or group having a higher electronegativity than the group -0R, and the n X's may be the same or different.

Examples of such X include residues of compounds that normally exhibit stronger acidity than alcohol HOR. More preferable examples of X include residues of organic acids and inorganic acids, such as R″COO
-, /ClO4-, B4O7, etc. can be mentioned.

\If there are two or more bonds in X, it will bond with Ti atoms within the same molecule or between different molecules,
Can be reticulated.

In the above, R'' is not particularly limited, but from the viewpoint of reactivity and steric hindrance, it is preferably an organic group having 6 or less carbon atoms, and more preferably a straight chain. n X's may be the same or different. In addition, -R in formula [1] is an alkyl group, preferably having 1 to 5 carbon atoms, particularly preferably 2 to m carbon atoms.

Examples of such groups include ethyl, propyl, butyl, and the like. (Nxm+1) -Rs may be the same or different. Z is as described above and is the group mentioned in X or -0R.

Further, l and m are O, 1, or 2, and satisfy 1+m=2. In addition, in the case of n-mers, n l and m
satisfies Σ1/Σm=0.1 to 2.5.
If Σl/Σm is smaller than this range, the stability of the titanium compound will not improve much and it will be difficult to form a coating, and if it exceeds this range, the performance of the formed titanium oxide thin film will deteriorate. n is an integer from 1 to 30. Although the value of n does not have to be single, it is preferable for the distribution of n to have a maximum value of 25 or less in terms of coating operation. The titanium compound represented by the formula [1] is not limited by its manufacturing method, but an easy method for manufacturing the titanium compound includes a method of reacting an alkyl titanate with an acid having the component x. .

In many cases, l and m in formula [1] can be controlled by adjusting the amount of acid used in the reaction. Alkyl titanates applicable to such a reaction are represented by the general formula TipOqRr [wherein R is as described above, and P, q, and r are positive integers]. Among such alkyl titanates, P, Those in which q and r satisfy the following three formulas are convenient for use in the present invention.

The acid to be reacted with the alkyl titanate is a compound capable of providing the above-mentioned component x, such as (1)
Phenol, thiophenol (Ii) formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid,
Valeric acid, undecanoic acid, oleic acid, cyclohexanecarboxylic acid, monochloroacetic acid, benzoic acid, oxalic acid, succinic acid, adipic acid (Ili), hydrogen chloride, hydrogen bromide, sulfuric acid, phosphoric acid, polyphosphoric acid, boric acid, perchloric acid , benzenesulfonic acid, among which those listed under (Ii) and (IiO) are preferred, those with a low boiling point are particularly preferred, and formic acid, acetic acid, propionic acid, butyric acid, and hydrogen chloride are preferred.

In addition to the above-mentioned method, there is also a method of synthesizing a titanium halide by substituting a part of the halogen atoms with an alkoxy group.

In order to form a titanium oxide film from the titanium compound represented by the above formula [1], one or more of the titanium compounds are usually dissolved in a suitable solvent to form a solution, and the solution is applied to a suitable base material. This can be achieved by pouring it onto the surface to form a liquid film and then heating it in the presence or absence of moisture.

Moisture requirements vary depending on the type of titanium compound. Further, in order to efficiently remove by-products, it is usually heated in a stream of air or inert gas. As such a solvent, a wide range of aliphatic, alicyclic, aromatic, and heterocyclic solvents can be used, and solvents such as alcohols, ketones, esters, and ethers can also be used. Examples of such solvents include hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, methanol, ethanol, isopropyl alcohol, propyl alcohol, butanol, cyclohexanol, tetrahydrofuran, dioxane, acetone, methyl ethyl ketone, ethyl acetate, butyl acetate. , chloroform, methylcellosomb, etc., and these may be used alone or as a mixture of two or more.

Further, the solvent and additives are appropriately selected depending on the desired conditions of the titanium oxide film (for example, adhesion to the substrate or formation of a self-supporting film). Further, the concentration of the titanium compound may also vary depending on the purpose, but 0.5 to 30 Wt% is usually applied, and 1 to 10 Wt% is preferable when forming a thin film. Any conventionally known means can be applied for the licking, and the heat treatment is usually performed at a temperature of 90 to 220
The objective can be achieved in 10 seconds to 6 seconds at °C. Hereinafter, further explanation will be given with reference to Examples.

Examples 1 to 4 The following formula [where R is -CH2.CH2.CH3 or -CH2.
CH2, CH2, CH3, and n is 4 or 10.

See Table 1 for combinations of R and n. ] was dissolved in a predetermined solvent to a concentration of 3.5 wt%, and a predetermined amount of acid HX (see Table 1 for X) was dissolved.

) was added dropwise under stirring at a temperature of room temperature to 50° C., and reacted to form the following formula [where X, R, Z, I, m, and n are shown in Table 1].

Note that I and m are average values. ] A solution of a titanium compound represented by the following formula was obtained.

This solution was coated on aluminum foil and polyethylene terephthalate film to a thickness of several microns using a percoater, and heated in a hot air dryer at 140° C. for 5 minutes to form a titanium oxide thin film.

Depending on the presence or absence of cloudiness of the coating liquid applied on the aluminum foil,
The quality of the coating film was determined, and the carbon content in the thin film was measured using the titanium oxide thin film formed thereon.

Claims (1)

[Claims] 1 The following general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [However, in the formula, X is an atom and/or group with higher electronegativity than the group -OR, and R is the number of carbon atoms. 1 to 20 alkyl groups, Z is a group -OR or an atom or group with higher electronegativity than the group -OR, and 1 and m are 0 or 1
or 2, satisfying l+m=2, and n is an integer from 1 to 30. It is also assumed that n l's and m's satisfy Σl/Σm=0.1 to 2.5. ] A method for producing a titanium oxide film, which comprises forming a titanium compound represented by the following by heat treatment.