WO2006123425A1

WO2006123425A1 - Process for producing solution for forming titanium oxide film

Info

Publication number: WO2006123425A1
Application number: PCT/JP2005/009276
Authority: WO
Inventors: Mihoko Okada
Original assignee: Axtis Company
Priority date: 2005-05-20
Filing date: 2005-05-20
Publication date: 2006-11-23

Abstract

[PROBLEMS] To provide a process for producing a solution for forming a titanium oxide film that enables reduction of production cost by reusing at least part of water to be used upon washing and effective utilization of water to be used upon washing or the like by recycling the water. [MEANS FOR SOLVING PROBLEMS] The process for producing a solution for forming a titanium oxide film according to the present invention comprises a deposition step of depositing and precipitating a peroxotitanium hydrate; a washing step of washing the solution containing the precipitate of peroxotitanium hydrate with water and then removing an ionic substance and impurities by filtration; and a dispersion step of dispersing the precipitate of the peroxotitanium hydrate in water, and is characterized in that in the washing step, at least part of water used for washing is passed through a filter formed of a porous ceramic or sponge cucumber, and the water passed through the filter is reused.

Description

Specification

Method for producing titanium oxide film forming solution

Technical field

TECHNICAL FIELD [0001] The present invention relates to a method for producing a titanium oxide film forming solution, and more particularly to a method for producing an aqueous titanium oxide film forming solution containing peroxotitanic acid modified with a peroxo group.

Background art

[0002] As a method for forming a titanium oxide film, a method of coating, drying, firing, etc., a dispersion containing fine particles of titanium oxide is known. As such a method, for example, a method in which a dispersion prepared by sol-gel method from titanium alkoxide on a substrate is applied and dried, a method in which titanium alkoxide is directly applied, dried and then fired is known. In these methods, since acids and organic substances are included in the dispersion, etc., it was necessary to remove these organic substances by heating to high temperatures when firing the coating film.

[0003] In addition, the above dispersion must use an acid such as hydrochloric acid or an organic dispersant as a dispersant. Gelation and agglomeration occurred, and their stability was bad. In addition, since the dispersion contains acid, the materials that can be applied are limited, and harmful halogen compounds are produced during the firing stage. Furthermore, in order to improve the adhesion of the coating film and obtain a dense film, the firing temperature requires an abnormality of several hundred degrees, and there are restrictions on its use in materials such as plastics, metals, low melting glass, and building materials. The

[0004] In order to solve such problems, a solution for forming a peroxotitanium-based oxide-titanium film

(Eg, peroxotitanic acid aqueous solution, peroxo-modified anatase sol, and mixtures thereof). Such a solution for forming a titanium oxide film is produced, for example, by a method as described in Patent Document 1.

[0005] In Patent Document 1, as a method for producing a solution for forming a titanium oxide film, (1) a peroxotitanium hydrate polymer precipitation step, (2) an ionic substance or impurity removal step, and ( 3) Formation process of aqueous solution of peroxotitanium hydrate A manufacturing method is described.

[0006] In the above step (2), the liquid containing the precipitate of the peroxotitanium hydrate polymer is washed or subjected to a treatment such as filtration and washing, so that it is contained in the liquid. Nitrogen ions, chlorine ions, or impurities derived from raw materials are removed.

[0007] Patent Document 1: Japanese Patent No. 3490013

Disclosure of the invention

Problems to be solved by the invention

[0008] However, when filtering and washing as described above, for example, about 10 to 12 tons of water is required to wash a precipitate containing about 1 ton of titanium oxide. However, there were problems in terms of cost and effective use of resources.

[0009] Therefore, the present invention has been made in view of such problems, and its object is to reduce the manufacturing cost by reusing at least a part of water used for cleaning.

Therefore, an object of the present invention is to provide a new and improved method for producing a solution for forming a titanium oxide film that can recycle and effectively use water used for cleaning.

Means for solving the problem

[0010] In order to reduce manufacturing costs and effectively use water, which is a limited resource, the present inventor has conducted intensive research to recycle and reuse water used in, for example, washing and filtration. As a result, it has been found that water can be reused by using a filter formed of porous ceramics such as ceramic unglazed, and the present invention has been completed based on this finding.

[0011] That is, according to one aspect of the present invention, an ionic substance is obtained by passing through a precipitation step of precipitating peroxotitanium hydrate and washing the solution containing the peroxotitanium hydrate precipitate with water. And a washing step for removing impurities, and a dispersion step for dispersing the precipitate of peroxotitanium hydrate in water. In the washing step, at least a part of the water used for washing is made of porous ceramics or The present invention provides a method for producing a solution for forming a titanium oxide film, which is characterized in that water passed through a filter formed by hechima is reused.

[0012] In the cleaning step, at least a part of the water used for cleaning is passed through a filter. Before passing, it may be passed through a second filter different from the filter. Examples of such a second filter include a carbon fiber with a photocatalytic coating, a reverse osmosis membrane, and a filter made of the same material (made of ceramic or hechima).

[0013] Further, the filter is coated with a peroxotitanic acid aqueous solution, a peroxo-modified anatase solution, and a mixture thereof, and at least a part of the water used for cleaning is passed through the filter in the cleaning step or When passing through the filter, UV light may be irradiated to the filter coated with aqueous peroxotitanic acid solution, peroxo-modified anatase sol, or a mixture of these.

The invention's effect

[0014] According to the present invention, at least a part of water used for cleaning is reused after passing through a filter formed of a predetermined material, thereby reducing manufacturing costs and cleaning. In this case, it is possible to provide a method for producing a solution for forming a titanium oxide film capable of recycling and effectively using water.

BEST MODE FOR CARRYING OUT THE INVENTION

[0015] Hereinafter, preferred embodiments of the present invention will be described in detail.

[0016] As described above, the present invention includes a precipitation step of precipitating peroxotitanium hydrate, and washing and washing the solution containing the peroxotitanium hydrate precipitate with water, followed by filtration. A cleaning step for removing impurities and a dispersion step for dispersing the precipitate of peroxotitanium hydrate in water. In the cleaning step, at least part of the water used for cleaning is formed by porous ceramics or hechima. This is a method for producing a solution for forming a titanium oxide film, characterized by reusing the water passed through the filter.

Specifically, the method for producing a titanium oxide film forming solution according to an embodiment of the present invention includes the following steps.

[0018] (1) Precipitation step of precipitating peroxotitanium hydrate

In this process, first, soluble titanium compounds such as tetrasalt and titanium are diluted with water, and an appropriate amount of peroxy hydrogen water is added to form a brown peroxo complex. Next, a basic substance such as ammonia is added to prepare an aqueous solution of yellow peroxotitanium hydrate. This aqueous solution is allowed to stand at room temperature or heated to precipitate peroxotitanium hydrate.

[0019] (2) Cleaning step for removing ionic substances and impurities

Next, the solution containing the precipitate of peroxotitanium hydrate obtained in the above step (1) is washed or filtered and washed to obtain ammonia ions and chlorine ions contained in the solution. To remove impurities derived from ionic substances and raw materials

[0020] In this embodiment, in the cleaning step, at least a part of the water used for cleaning is passed through a filter formed of porous ceramics or hechima, and the water passed through the filter is reused. The details are described later.

[0021] (3) Dispersing step of dispersing peroxotitanium hydrate precipitate in water

Next, peroxotitanium hydrate, from which ionic substances and impurities have been removed by washing treatment, is cooled to room temperature or below, and hydrogen peroxide water is added. A solution in which substances are dispersed in water can be obtained.

Here, examples of the soluble titanium compound used as a raw material in the step (1) include titanium tetrachloride, titanium sulfate, titanium nitrate, and alkoxy titanium. In addition, the amount of peracid-hydrogen water to be added to the aqueous solution of soluble titanium-based compound must be at least 1 in terms of mole ratio. Peroxo is not completed. In addition, since some of the added peracid-hydrogen water decomposes without participating in the reaction, the peracid-hydrogen is adjusted so that the molar ratio of peracid-hydrogen-Z titanium is more than 1. It is preferable to add.

[0023] In addition, when hydrogen peroxide solution is added to a solution containing soluble titanium, peroxidation occurs almost instantaneously, and when pH is 3 or less, it is dissolved mainly as a cation. It exists as an anion of peroxotitanium hydrate. This is thought to be because the higher the pH, the faster the condensation and the precipitation of amorphous peroxotitanium hydrate. Even when a basic substance is added, it takes longer to precipitate peroxotitanium hydrate if the pH is low. It is preferable to add it, and it is more preferable to adjust the pH so that it becomes neutral by adding a basic substance.

[0024] The yellow transparent liquid force of peroxotitanium hydrate produced by adding a basic substance may also be allowed to stand at room temperature when it produces a yellow precipitate, but it precipitates by heating. Can be promoted. Precipitation can be further promoted by stirring. However, heating to 80 ° C or higher may produce anatase-type crystals, so heating is preferably performed at a temperature of 80 ° C or lower! /.

[0025] Further, in the above step (2), when removing ionic substances such as ammonium ions and chlorine ions contained in the solution and impurities derived from the raw material from the solution containing the deposited precipitate, For example, cleaning methods using water such as decantation and filtration cleaning can be used. In addition to these cleaning methods, it is possible to use a method that removes ionic substances using reverse osmosis or ion exchange.

[0026] If there is a large amount of residual impurities, the stability and properties of the finally obtained peroxotitanium hydrate aqueous solution will be adversely affected, so it is desirable to treat it sufficiently. In particular, if the removal of anions such as chloride ions is insufficient, the solution may become cloudy instead of being completely transparent. From this point of view, the cleaning requires a large amount of water. For example, about 10 to 12 tons of water was required to wash a precipitate containing about 1 ton of peroxotitanium, which was problematic in terms of cost and effective use of resources. It should be noted that in the processing of the precipitate, it is necessary to prevent the precipitate from drying because it dehydrates and solidifies when the precipitate is dried, and adversely affects the subsequent process (dispersion process).

[0027] Next, in the above step (3), when hydrogen peroxide solution is added to the liquid containing the deposited precipitate, the amount of the peroxygen-hydrogen water to be added is The ratio of hydrogen oxide Z titanium is preferably 1 or more, and if it is less, it may not be completely dispersed. In addition, if the temperature is preliminarily cooled to 40 ° C or lower, it is possible to prevent overheating of the liquid due to reaction heat, etc., and to prevent re-aggregation of the dispersed peroxotitanium hydrate. . When the temperature of the solution during the reaction is 40 ° C or higher, the solution will be very thickened. Therefore, the solution temperature should be 40 ° C or lower, and preferably cooled to 20 ° C or lower.

[0028] In the above-described embodiment, peroxotitanium hydration that has already been peroxotized. Although a solution for forming an acid / titanium film is produced by dispersing an object in water, the method for producing an acid / titanium film forming solution is not limited to this method. For example, titanium hydroxide or acid Alternatively, it may be produced by directly adding hydrogen peroxide water to titanium hydrate. However, when the latter method is used, the peroxidation and dissolution occur continuously, resulting in large heat generation. However, with the former method, the reaction proceeds relatively slowly without so much heat generation. An aqueous solution (dispersion) of peroxotitanium hydrate with excellent quality can be obtained.

[0029] The titanium oxide film forming solution according to the present embodiment is an amorphous titanium oxide film when heat-treated at less than 200 ° C after being applied as a coating agent, and crystalline when heat-treated at 200 ° C or higher. A (anatase type) dense acid-titanium film can be formed. These films have excellent acid resistance and can be used as various anticorrosion coatings.

[0030] In addition, since anatase sol that has been heat-treated at 80 ° C or higher can form a crystalline titanium oxide titanium film simply by coating, the heat treatment cannot be performed. Useful as a coating agent. In such a method, it can be used for various applications such as protective coatings and photocatalysts, and it is possible to obtain a material having a relatively high density and good adhesion at a relatively low temperature.

[0031] In addition, as a base material to which the titanium oxide film forming solution manufactured as described above is applied, ceramics, ceramics, metals, plastics, fibers, building materials, glass, etc. can withstand heat treatment according to applications. It can be applied to any substrate as long as it is made of a material that can be obtained, and it is also possible to carry out surface treatment of the inside of other antibodies and powder.

[0032] Next, features of the method for producing a titanium oxide film forming solution according to the present embodiment will be described in detail.

[0033] As described above, a large amount of water is required for washing in the step (2). For example, about 10 to 12 tons of water is required to wash the precipitate containing about 1 ton of peroxotitanium, and there has been a problem in terms of cost and effective use of resources.

[0034] In addition, when a peroxotitanic acid aqueous solution containing amorphous acid-titanium having no photocatalytic activity is heated to prepare a crystalline (anatase-type) peroxo-modified anatase sol, heat is applied. Since this is not constant, the size of the crystal Variation of Therefore, in order to improve the dispersibility, filtration is performed in order to separate only crystals with small particle diameters and small variations, but a large amount of water is also required for this filtration.

. The particle size of the titanium oxide crystal after filtration is very fine, 10nm to 20nm, and there is little variation in particle size.

[0035] Therefore, in the method for producing a titanium oxide film forming solution according to the present embodiment, at least a part of the water used for cleaning in the cleaning step (step (2)) is porous ceramics or The water passed through this filter is reused through a filter formed by hechima.

[0036] Specifically, in the above washing step, about 10 to 12 tons of water is used at one time to wash the precipitate containing about 1 ton of peroxotitanium. After passing 5 tons through the filter, save it. A small amount of ammonia may be added during storage.

[0037] Cleaning to remove ionic substances and impurities is usually performed a plurality of times in order to remove them as completely as possible, but by using the water stored as described above for subsequent cleanings, Can be used effectively, and costs can be reduced, which in turn can improve productivity.

[0038] Here, as the filter, it is preferable to use a filter formed of porous ceramic or hechima. By using these materials, the ionic substances and impurities contained in the water used for the above cleaning can be suitably removed, and they can be used for the next cleaning.

[0039] If a porous ceramic is used as the filter, the shape and pore diameter of the filter can be easily changed. More specifically, impurities can be collected when manufacturing a filter using ceramic, but as the amount of impurities increases, a filter with a larger pore diameter can be manufactured. The smaller the number, the smaller the pore diameter can be produced. This makes it possible to easily manufacture a filter according to the particle size of the target substance removed by filtration. Furthermore, if porous ceramic is used as a filter, even if impurities accumulate in the pores of the filter and cause clogging, the ceramic filter can be heated to burn and evaporate the impurities. To remove impurities. You can remove the clogging. This allows the filter to be reused by heating and firing without replacing the filter.

[0040] Further, if hechima is used as a filter, a large surface area can be secured by the fibres in which hechima is entangled. Thus, by securing a large surface area, impurities can be allowed to pass through the filter. Furthermore, as will be described later, the surface of the filter may be coated with a photocatalytic effect. Even in such a case, the photocatalytic reaction can be performed efficiently by ensuring a large surface area. Caro, because hechima is a natural fiber, it is heat resistant. For example, it can sufficiently withstand heating up to about 120 ° C.

[0041] In addition, there is an advantage that even if ceramic or hechima is used as a filter, the environment is not harmed during the cleaning process.

[0042] The shape of the filter can be, for example, a cylindrical shape or a cup shape. In the case of a cylindrical filter, an opening is formed at the top to allow the water after washing to enter the filter, and the bottom is closed. On the other hand, in the case of a cup-shaped filter, it is preferable to form a mold with a mesh-like material made of stainless steel or the like so that it can withstand water pressure. In the case of cup-shaped filters, for example, 1 to 10 filters can be used in layers, depending on the amount of water to be filtered and the filtration time.

[0043] Further, in order to apply a coating having a photocatalytic effect on the surface of the filter, a peroxotitanic acid aqueous solution, a peroxo-modified anatase sol, and a mixture thereof were applied and used for cleaning in the cleaning step. Before or when the water is passed through the filter, the filter coated with the peroxotitanic acid aqueous solution, the peroxo-modified anatase sol, or a mixture thereof may be irradiated with ultraviolet rays.

[0044] In this way, an aqueous peroxotitanic acid solution, a peroxo-modified anatase sol, and a mixture thereof are applied to the surface of the filter, and at least a part of the water used for washing in the washing step is passed through the filter or When passing through the filter, the applied coating is exposed to ultraviolet light so that the applied coating has photocatalytic activity. Become. Therefore, contamination of the filter itself can be prevented by the photocatalytic effect (self-cleaning function), and impurities contained in the water after passing through the filter can be decomposed by the effect of the photocatalyst. The effect can be further enhanced.

[0045] Specifically, the effect of removing the salt and the like contained in the washed water used in the washing step and purifying the water is enhanced. In addition, even when this water is drained without being reused in the next washing process, environmental standards can be met by reducing the concentration of salt and other substances. It can also remove microorganisms contained in fresh water, seawater, and air to prevent breeding.

In the present embodiment, in the cleaning step, at least a part of the water used for cleaning may be passed through another filter before passing through the filter as described above. As such a filter, carbon fiber coated with the above-mentioned photocatalytic effect or a reverse osmosis membrane can be used, but it is preferable to use a carbon fiber filter. This is because carbon fiber can secure a large surface area as in the case of Hechima described above, and impurities can be made difficult to pass through the filter, and photocatalytic reaction can be carried out effectively! It is because it has.

[0047] In this way, by passing through another filter, the effect of removing ionic substances and impurities can be further enhanced. Here, in general, reverse osmosis membranes that use carbon fiber are often used for desalination of seawater. By using reverse osmosis membranes in this way, seawater that exists in large quantities on the earth is used. Can be used for cleaning in the present embodiment.

[0048] A filter of the same material may be used instead of another filter. In this case, for example, the filter through which water passes first has a large pore size (coarse), and the filter through which water passes next has a small pore size (fine mesh). It can be applied with coating. By adopting such a configuration, it is possible to remove large dusts and germs (those that are large enough to be confirmed with the naked eye) with the first filter, and then secondly remove small impurities and ionic substances that cannot be confirmed with the naked eye. The removal effect can be drastically improved by removing impurities in two stages, such as removal with a filter with a photocatalyst coating. [0049] While the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

Industrial applicability

[0050] The present invention is applicable to a method for producing a solution for forming a titanium oxide film, and particularly applicable to a method for producing an aqueous solution for forming a titanium oxide film containing peroxotitanic acid modified with a peroxo group. is there.

Claims

The scope of the claims

[1] a precipitation step of precipitating peroxotitanium hydrate;

A washing step for removing ionic substances and impurities by washing the solution containing the precipitate of peroxotitanium hydrate with water and then filtering;

Dispersing the precipitate of the peroxotitanium hydrate in water;

In the cleaning step, at least a part of the water used for the cleaning is passed through a filter formed of porous ceramics or hechima, and the water passed through the filter is reused. A method for producing a forming solution.

[2] The method according to claim 1, wherein in the cleaning step, at least part of the water used for the cleaning is passed through a second filter different from the filter before passing through the filter. A method for producing a solution for forming titanium oxide.

[3] The filter is coated with a peroxotitanic acid aqueous solution, a peroxo-modified anatase sol, and a mixture thereof.

2. The titanium oxide according to claim 1, wherein in the cleaning step, at least a part of water used for the cleaning is irradiated with ultraviolet rays before or when the water is passed through the filter. A method for producing a film-forming solution.