JP2005105138A - Aqueous liquid for formation of photocatalyst film excellent in transparency and stability, method for producing the same and method for producing structure by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous liquid for formation of a photocatalyst film composed of an anatase type titanium peroxide fine particle dispersion and excellent in transparency and stability without being influenced by the content of ammonium ion used in a production process and to provide a method for producing the aqueous liquid for formation of photocatalyst and to provide a method for producing a structure by using the aqueous liquid. <P>SOLUTION: A salt solution of tetravalent titanium is reacted with an aqueous solution of ammonium to form a hydroxide of titanium and the hydroxide is peroxidized with an oxidizing agent and ultrafine-particle amorphous titanium peroxide is formed thereby and the titanium peroxide is dislocated to an anatase form by heat treatment to form an anatase type titanium peroxide fine particle dispersion. In any of the processes for forming the dispersion, a silicon compound such as silica sol is mixed therein to produce the aqueous liquid for formation of photocatalyst film. The aqueous liquid is applied to the surface of a substrate and a film is formed to produce the structure having the photocatalyst film on the surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a photocatalyst film-forming water solution having excellent transparency and stability, a method for producing the water solution, and a method for producing a structure using the water solution. More specifically, a water solution for forming a photocatalyst film that contains anatase-type titanium oxide fine particles and is excellent in transparency and stability without being affected by the content of ammonium ions used in the production process, and the water solution And a structure manufacturing method using the same.

Titanium-containing material is applied to the surface of various materials such as plate glass, plate-like ceramics or tiles to form a photocatalytic film made of titanium oxide (titania). Antifouling, antibacterial, and gas expressed by the photocatalytic film Conventionally, various functions such as decomposition and decomposition of harmful organic substances have been developed.
As a method for forming the titanium oxide film, a method is known in which a dispersion containing a fine particle of titanium oxide or a titanium compound solution is applied to the surface of the substrate, and then dried or further subjected to low-temperature firing if necessary. .

In particular, as titanium oxide used for developing photocatalytic performance, it is known that not only titanium dioxide such as anatase type or rutile type titanium oxide but also titanium oxide having a peroxo group, that is, titanium peroxide can be used. .
As for the titanium peroxide, only the anatase type has catalytic performance, which is also known (see Patent Document 1).
Since the anatase-type titanium peroxide has photocatalytic performance as described above, it is also described in the above publication that a film is formed on the surface of a substrate of various structures and used as a photocatalytic film.

Then, the photocatalyst film-forming aqueous solution composed of the dispersion of the anatase-type titanium oxide fine particles typically reacts a salt solution of tetravalent titanium with a basic solution such as ammonia to hydroxylate titanium. It is manufactured by forming a product, washing the hydroxide with water, then peroxolating with an oxidizing agent, thereby forming an ultra-fine particle of amorphous titanium peroxide, and then transferring it to anatase type by heat treatment. (See Patent Documents 1 and 2).
Note that amorphous titanium oxide has no photocatalytic performance but has excellent binding performance, and has been proposed to be used as a binder for photocatalytic particles when forming a photocatalytic coating (see Patent Document 3).

The presence of cations such as ammonium ions derived from the basic solution used in the production process of the photocatalyst film-forming water solution affects the stability and transparency of the produced aqueous solution, and also promotes anataseization. However, it was necessary to separate and remove it, and therefore, it was necessary to perform washing after mixing the basic solution to form a hydroxide.
As a method for efficiently performing the separation and removal, a method using a cation exchange resin has been proposed (see Patent Document 4).

[Prior art documents]
JP 10-67516 A JP-A-9-71418 Japanese Patent Laid-Open No. 9-262481 Japanese Patent No. 312658

All of the technologies related to the photocatalyst film-forming aqueous solution containing these anatase-type titanium oxide fine particles are based on Mr. Hiromichi Ichinose, who subsequently made the formed aqueous solution excellent in stability and transparency. In addition to reducing the amount of ammonium ions as much as possible, it is also necessary that the ions be present in a predetermined amount or more.
According to this, it is said that a suspended pale yellow film-forming aqueous solution having excellent stability can be formed only when the same ion is present at about 500 ppm, but a conventional method for producing anatase-type titanium oxide fine particle dispersion However, none of them had sufficient stability and transparency.

Therefore, the present inventor does not require complicated and laborious operations such as removal and separation of ammonium ions by washing or ion exchange, or adjustment to make the ions into a predetermined amount, and is stable and transparent. As a result, the present invention has succeeded in developing a water solution for forming a photocatalyst film composed of a dispersion of anatase-type titanium oxide fine particles having better properties.
Accordingly, the present invention provides a water solution for forming a photocatalyst film that is excellent in transparency and stability, and does not require an ammonium ion removal process and an adjustment process for adjusting the concentration of the ions to a predetermined concentration, and a method for producing the same This is a problem to be solved by the invention.
Another object of the present invention is to form a film on a substrate using the same.

The present invention provides an aqueous solution for forming a photocatalyst film that is excellent in transparency and stability in order to solve the above problems, a method for producing the same, and a method for producing a structure using the same. The aqueous liquid for forming a photocatalyst film having excellent stability is characterized by comprising an anatase-type titanium oxide fine particle dispersion having a peroxo group containing a silicon compound.
In addition, the transparency and stability are expressed without being affected by the content of ammonium ions used in the production process, and are excellent characteristics.

There are three methods for producing the photocatalyst film-forming aqueous liquid.
In the first production method, a salt solution of tetravalent titanium and an aqueous ammonia solution are reacted to form a hydroxide of titanium, and the hydroxide is peroxylated with an oxidizing agent, whereby ultrafine particles are obtained. Amorphous titanium peroxide is formed, and further transferred to anatase titanium peroxide by heat treatment, and a silicon compound is mixed in any of these processes.

Furthermore, in the second production method, a tetravalent titanium salt solution is peroxylated with an oxidizing agent, and this is reacted with an aqueous ammonia solution to form a hydroxide to form an ultra-fine particle amorphous titanium peroxide. Further, it is transferred to anatase-type titanium peroxide by further heat treatment, and a silicon compound is mixed in any of these processes.
In the third production method, ultrafine particles are obtained by reacting tetrametallic titanium powder or titanium oxide powder, hydrogen peroxide, and aqueous ammonia solution, and simultaneously performing titanium hydroxide formation and peroxoation. Amorphous titanium peroxide is formed, and further transferred to anatase titanium peroxide by heat treatment, and a silicon compound is mixed in any of these processes.

In addition, a method for producing a structure having a photocatalyst film on its surface includes a water solution for forming a photocatalyst film excellent in transparency and stability, comprising an anatase-type titanium peroxide fine particle dispersion having a peroxo group containing a silicon compound. A coating film is formed by applying various coating film materials including the above to the surface of a base material.

In the present invention, a silicon compound is present in the aqueous solution for forming a photocatalyst film, and this presence makes it possible to maintain transparency and stability without considering the residual ammonium ions derived from ammonia used for neutralization in the production process. A water solution for forming a photocatalyst film having excellent properties can be produced.
That is, a water solution for forming a photocatalyst film excellent in transparency and stability can be produced without performing impurity removal treatment and concentration adjustment treatment of the same ions for leaving a predetermined amount of the remaining ammonium ions.

For example, it is not necessary to adjust the amount of ammonium ions to make the residual ammonium ions in the photocatalyst film-forming aqueous solution about 500 ppm.
As described above, in the present invention, a water solution for forming a photocatalyst film excellent in transparency and stability can be produced without performing complicated operations such as separation and removal or concentration adjustment for the remaining ammonium ions.
Thus, in the present invention, the formation aqueous solution has excellent transparency and stability over time due to the inclusion of the silicon compound.
As a result, a photocatalyst film can be formed without impairing the transparency property of the substrate even when coated on glass or the like having excellent transparency.

In addition, since it is excellent in stability over time, it does not become nervous with respect to handling during storage, and even when stored for a long period of time, there is no discoloration, no alteration, etc., and it is excellent in usability.
Furthermore, since the titanium peroxide in the aqueous solution for forming the photocatalyst film is anatase type, it is possible to form the photocatalyst film at room temperature without requiring high-temperature heating after the film is formed. It is also excellent.
Of course, amorphous titanium peroxide or other additive for coating film may be mixed as long as the characteristics such as transparency and stability of the photocatalyst film forming water solution of the present invention are not impaired.

As described above, the present invention provides a water solution for forming a photocatalyst film excellent in transparency and stability, a method for producing the same, and a method for producing a structure using the same.
Although these are explained in full detail below, this invention is specified by description of a claim, and is not limited at all by the detailed matter.

The aqueous liquid for forming a photocatalyst film having excellent transparency and stability according to the present invention is composed of a dispersion of anatase-type titanium oxide fine particles having a peroxo group containing a silicon compound as described above, and the presence of the silicon compound. Regardless of the content of ammonium ions, which are impurities, it is possible to form an aqueous solution for forming a photocatalyst film that is excellent in transparency and stability, and as a result, even when stored for a long period of time, it may cause precipitation or discoloration. And can be stored stably.
As described above, the method for producing a titanium oxide-containing aqueous solution for forming a film according to the present invention includes three production methods, but the first production method is preferred in terms of simplification of the process.

The tetravalent titanium salt solution used in the first and second production methods can form a titanium hydroxide gel, also called orthotitanic acid (H ₄ TiO ₄ ), when reacted with aqueous ammonia. Any titanium salt solution can be used.
Examples of the titanium salt include water-soluble inorganic acid salts of titanium such as titanium tetrachloride, titanium sulfate, titanium nitrate, or titanium phosphate. In addition, water-soluble organic acid salts such as titanium oxalate can be exemplified.
Of these various titanium compounds, titanium tetrachloride is preferred in that no components other than titanium in the titanium compound remain in the produced film forming solution.

The concentrations of the tetravalent titanium salt solution and the aqueous ammonia solution are not particularly limited as long as the titanium hydroxide gel can be formed during the reaction, but a relatively dilute solution is preferable. Specifically, the tetravalent titanium salt solution may be 0.01 to 5 wt%, preferably 0.3 to 0.9 wt%.
Moreover, 0.5-10 wt% is good for aqueous ammonia solution, Preferably 1.0-4.0 wt% is good.
In addition, regarding the density | concentration of aqueous ammonia solution, a 2-4 times density | concentration liquid is used in the 3rd manufacturing method below compared with the above.

  Further, in the third production method, metal titanium powder or titanium oxide powder is used as a titanium raw material, and these include peroxotitanium complex or peroxotitanium hydrate in the presence of hydrogen peroxide and aqueous ammonia. Can be used without particular limitation, but the metal titanium powder has a purity of 99 to 99.9% and a particle size of 45 to 250 μm, and the titanium oxide powder can be oxidized. Not only titanium powder but also hydrous titanium oxide powder may be used.

The silicon compound used in the first to third production methods is not particularly limited, and examples thereof include silica sol, alkali silicate such as water glass, or alkali borosilicate such as sodium borosilicate. As examples, silica sol is preferable in terms of removal of unnecessary substances and economical efficiency.
The aqueous solution for forming a photocatalytic film of the present invention is a dispersion of anatase-type titanium oxide fine particles having a peroxo group containing a silicon compound, and the dispersion contains anatase-type titanium oxide fine particles having a peroxo group and Since the silicon compound coexists, both of them may be finally contained in the forming aqueous solution.

As described above, in any of the first to third production methods, the silicon compound is finally produced in any of the steps of producing an anatase-type titanium peroxide-containing dispersion. What is necessary is just to mix so that it may coexist with anatase type titanium peroxide in a liquid, and the mixing time in particular is not restrict | limited.
Since it is as mentioned above, a silicon compound is mixed in the process of manufacturing an anatase type titanium peroxide containing dispersion liquid, and even if it adds after titanium peroxide transfers to anatase type, it is not effective.

The concentration of titanium peroxide in the aqueous solution for film formation (the total amount including the coexisting compounds in the case of doped titanium peroxide) is preferably 0.05 to 15 wt%, preferably 0.1 to 5 wt%. Good.
The silicon compound coexisting with anatase-type titanium peroxide in the aqueous solution for forming a film has a concentration of 0.005 to 50.0 wt% of silicon in the silicon compound with respect to titanium oxide, preferably 2.0. -30 wt% is good.

As described above, the method for producing the photocatalyst film-forming aqueous liquid of the present invention is preferably the first production method. The anatase type having a peroxo group is the same procedure in the first production method. First, a method for producing a dispersion containing fine titanium oxide particles will be described.
In the production of the contained dispersion, a tetravalent titanium salt and ammonia water are mixed to first produce a hydroxide of titanium.
In this case, the concentration and temperature of the reaction solution are not particularly limited, but the former is preferably carried out in a dilute solution, and the latter is preferably carried out while cooling at room temperature or peroxo formation.

This reaction is a neutralization reaction, and it is desirable to adjust the pH from acidic to neutral, that is, pH 7.
After the reaction, the formed titanium hydroxide gel is solid-liquid separated by gravity sedimentation or centrifugation.
It is desirable to wash the hydroxide obtained following this separation with pure water in order to separate and remove the anions present therein.
Since this washing is for separating and removing anions, it is not necessary to control the concentration of ammonium ions, which are cations, and it is desirable to wash and remove together with anions.

Thereafter, by peroxylating titanium hydroxide with hydrogen peroxide, an aqueous liquid containing fine particles of titanium oxide having amorphous peroxo groups, that is, an amorphous titanium peroxide-containing dispersion is produced. However, it is preferable to cool before that.
Cooling at that time is preferably performed so that titanium hydroxide is 1 to 5 ° C.
The concentration of hydrogen peroxide used for this peroxoation is not particularly limited, but is preferably 30 to 40%.

By mixing titanium hydroxide and hydrogen peroxide as described above, the peroxo reaction proceeds gradually, and amorphous titanium peroxide is formed.
In that case, it is preferable to obtain a dispersion having a small particle size and excellent transparency. For this purpose, the reaction is preferably carried out at a low temperature in a short time.
In this way, a yellow and transparent amorphous titanium peroxide-containing aqueous liquid is obtained.

Subsequently, the amorphous titanium peroxide-containing dispersion is heated to be converted into an anatase type, and the heating temperature at that time may be 80 to 200 ° C, and preferably 90 to 120 ° C.
Further, the heating can be performed only by electricity or combustion heat, but it is preferable to use heating by electromagnetic waves in combination with these to shorten the heating time as much as possible according to the purpose.

The photocatalyst film-forming aqueous liquid produced by the first production method of the present invention can be produced by mixing a silicon compound in any of the processes for producing the anatase-type titanium oxide fine particle dispersion described above. The mixing timing is also shown in FIG.
Specifically, it can be prepared by mixing a silicon compound into the titanium compound aqueous solution, titanium hydroxide, amorphous titanium peroxide-containing dispersion liquid, etc. in the above process, but in view of concentration adjustment, amorphous type titanium peroxide-containing dispersion Liquid is preferred.

The mixing of both in the production of the film-forming aqueous liquid is typically performed by mixing an amorphous titanium peroxide-containing dispersion and a silicon compound sol, for example, a silica sol.
In addition, any method other than this is not excluded as long as both can be contained, and for example, it can be produced by adding a saccharide to a titanium peroxide-containing dispersion and mixing them. .

  Further, the film forming aqueous solution can be doped with a conductivity improving substance, such as aluminum, tin, chromium, nickel, antimony, iron, silver, cesium, indium, cerium, selenium, There are metal salts such as copper, manganese, platinum, tungsten, zirconium, and zinc, and some metals or nonmetals include hydroxides or oxides.

More specifically, the substance names are aluminum chloride, first and second tin chlorides, chromium chloride, nickel chloride, first and second antimony chlorides, first and second iron chlorides, silver nitrate, cesium chloride, Indium trichloride, cerium chloride, selenium tetrachloride, cupric chloride, manganese chloride, platinum chloride, tungsten tetrachloride, tungsten oxychloride, potassium tungstate, gallium chloride, zirconium oxychloride, zinc chloride And various metal salts.
In addition to metal salts, compounds such as indium hydroxide and silicotungstic acid can also be exemplified.

The water solution for forming a film of the present invention can be used for directly forming a film on the surface of a substrate, and can also be used by being incorporated in various material compositions such as a coating material for forming the film. .
As an object for directly forming a film, any material that requires photocatalytic ability or anatase type titanium oxide can be used without particular limitation. There are inorganic base materials such as tempered glass and tiles, and organic polymer sheets such as polycarbonate and acrylic plates.
In addition, various material compositions include paints such as paint, and organic polymer-containing plastering materials.

  More specifically, including these, various metal plates (stainless steel plates, aluminum plates, etc.), glass for building materials, glass for automobiles, various mirrors (bathrooms, washrooms, roads, reflectors), equipment protection glass (signals) , Sensors), glass tableware, refrigerated / frozen showcase glass, display glass, medical and dental mirrors, medical cameras such as endoscopes, metal fins for heat exchange, various paints, or plasterers containing organic materials In particular, it is effective to form a base material having cosmetic properties and transparency. However, when forming a film on an organic material base, a primer as a photocatalyst block layer is required.

Since the titanium oxide fine particles having a peroxo group in the aqueous solution for forming a film of the present invention are anatase type, a film having adhesion and photocatalytic performance can be formed only by natural drying after the coating, and then dried by heating. The photocatalyst film can be easily produced on the surface of the substrate without any problem.
However, it may be dried by heating. In that case, heating to 250 ° C. or higher will improve the density, adhesion and catalytic performance, but it will consume more energy than natural drying.

The thickness of the coating is 0.01 to 2.0 μm, preferably 0.1 to 1.0 μm, after drying and fixing.
The film forming means for forming the film is not particularly limited as long as the film having the above thickness can be formed, and examples thereof include a spray method, a spin method, a roll method, and a silk printing method. .

[Examples and Comparative Examples]
Below, the Example which manufactures the aqueous liquid for catalyst film formation of this invention and the comparative example which manufactures the aqueous liquid compared with it are described.
Moreover, since the test regarding transparency and stability of the water solution for film formation produced by these Examples and Comparative Examples was also performed, the results are also described.
In addition, this invention is not limited at all by these Examples and test results, and it cannot be overemphasized that it is specified by description of a claim.

To 1000 ml of pure water, 5.0 g of 30 wt% silica sol (manufactured by Catalytic Chemical Industry Co., Ltd.) and 20 g of 50% titanium tetrachloride solution (manufactured by Sumitomo Sitix Co., Ltd.) are added, and a pure water is added to prepare a solution of 2000 ml. .
Ammonia water diluted 10 times with 25% ammonia water (manufactured by Takasugi Pharmaceutical Co., Ltd.) was added dropwise thereto to adjust the pH to 6.9 to precipitate titanium hydroxide.
This precipitate is purely decanted and repeatedly washed so that the conductivity in the supernatant is 0.8 mS / m or less. When the conductivity is 0.788 mS / m, the washing is terminated. 690 g of a titanium hydroxide-containing liquid doped with 96 wt% solids concentration silica was produced.

Next, 30 g of 35% hydrogen peroxide (manufactured by Taiki Pharmaceutical Co., Ltd.) was added while cooling this containing liquid to 1 to 5 ° C. and stirred for 16 hours, and a 1.05 wt% solid doped with yellow transparent silica was added. 740 g of a dispersion of amorphous titanium peroxide having a partial concentration was obtained.
This dispersion had a silica concentration of 1600 ppm and an ammonium ion concentration of 110 ppm as measured by the indophenol method.
When 200 g of this was weighed and heated at a temperature of 100 ° C. for 5 hours, 115 g of anatase-type titanium peroxide dispersion doped with yellow and highly transparent silica was obtained at a concentration of 1.78 wt%.

A solution prepared by adding 40 g of a 50% titanium tetrachloride solution (manufactured by Sumitomo Sitix Co., Ltd.) to 2000 ml of pure water and adding pure water to make 4000 ml is prepared.
Ammonia water diluted 10 times with 25% ammonia water (manufactured by Takasugi Pharmaceutical Co., Ltd.) was added dropwise thereto to adjust the pH to 7.0 to precipitate titanium hydroxide.
The precipitate is decanted with pure water, and the washing is continued so that the conductivity in the supernatant is 0.8 mS / m or less. When the conductivity is 0.738 S / m, the washing is finished. 1720 g of a liquid containing 0.73 wt% hydroxide was prepared.
The ammonium ion concentration of this dispersion was 120 ppm as measured by the indophenol method.

Next, 100 g of 35% hydrogen peroxide (manufactured by Taiki Pharmaceutical Co., Ltd.) was added while cooling this containing liquid to 1 to 5 ° C. and stirred for 16 hours, and the yellow and transparent 0.86 wt% solid content amorphous 1810 g of a dispersion of type titanium peroxide was obtained.
Five transparent dispersions of the obtained amorphous amorphous titanium peroxide were weighed in 200 g units, and 30 wt% silica sol (manufactured by Catalyst Chemical Industry Co., Ltd.) was added to each of 0.01, 0.03, 0.05, 0 0.1 and 1.0 wt% were added to prepare the silica at concentrations of 50 ppm, 140 ppm, 250 ppm, 410 ppm and 3830 ppm.

Thereafter, the dispersion liquid of each amorphous titanium peroxide having the silica concentration thus prepared was heated at 100 ° C. for 5 hours.
As a result, the following aqueous dispersions of anatase-type titanium peroxide were obtained.
(1) When silica has a concentration of 50 ppm, 90 g of a dispersion having a solid concentration of 1.90 wt% is obtained.
(2) In the case of the same concentration of 140 ppm, 95 g of a dispersion having a solid content concentration of 1.79 wt% is obtained.
(3) In the case of the same concentration of 250 ppm, 96 g of a dispersion having a solid concentration of 1.80 wt% is obtained.
(4) In the case of the same concentration of 410 ppm, 99 g of the dispersion having a solid content concentration of 1.74 wt% is obtained.
(5) In the case of the same concentration of 3830 ppm, the dispersion having a solid content concentration of 1.71 wt% is 101 g.

[Comparative Example 1]
When 200 g of the transparent amorphous titanium peroxide dispersion prepared in Example 2 was weighed and heated at 100 ° C. for 5 hours, anatase titanium peroxide dispersion suspended in a pale yellow color was 110 g at a concentration of 1.52 wt%. Obtained.

[Comparative Example 2]
Four 200 g dispersions of transparent amorphous titanium peroxide prepared in Example 2 were weighed, and ammonia water obtained by diluting 25% ammonia water (manufactured by Takasugi Pharmaceutical Co., Ltd.) 10 times was added thereto. It adjusted so that it might become predetermined ammonium ion concentration (120ppm, 300ppm, 500ppm, 1000ppm).
When the amorphous titanium peroxide dispersion with the adjusted ammonium ion (NH ₄ ⁺ ) concentration was heated for 5 hours, the following were obtained.
(1) In the case of NH ₄ ⁺ concentrations of 120 ppm and 300 ppm, a solid content concentration of 1.78 wt% and 95 g of anatase-type titanium peroxide dispersion
(2) In the case of the same concentration of 500 ppm, the solid content concentration is 1.79 wt%, and 93 g of a low photocatalytic titanium peroxide dispersion not transferred to the anatase type
(3) In the case of the same concentration of 1000 ppm, the solid content concentration is 1.65 wt%, and the titanium peroxide dispersion does not transfer to 101 g of anatase type and has no photocatalytic property.

[Transparency test and stability test]
About the anatase type titanium peroxide dispersion liquid manufactured by the Example and the comparative example, the transparency test and the stability test were done as follows.
That is, in the transparency test, the color and transparency of the anatase-type titanium peroxide dispersion produced in Examples and Comparative Examples were visually observed. In addition, in the stability test, changes were observed visually after heating for 5 hours at 100 ° C., after 6 months, and after 1 year.
As for the results, Examples 1, 2 and Comparative Example 2 are as described in Tables 1 to 3.

About the result of each above-mentioned Example and a comparative example, when it shows as an outline | summary based on the said table | surface, it is as follows.
The anatase type titanium peroxide dispersion obtained in Example 1 has a silica concentration of 1600 ppm and an ammonium ion concentration of 110 ppm in the amorphous type.
The color was yellow and highly transparent, and it was stored in a cool dark place for a long time (6 months and 1 year). However, there was no discoloration or formation of precipitates, and there was no change in properties. Further, even after heating at 100 ° C. for 5 hours, it was highly transparent with no change.

In Example 2, five types of anatase-type titanium peroxide dispersions with silica concentrations of 50, 140, 250, 410, and 3830 ppm were prepared as described above, and the following properties were obtained for each silica concentration. An anatase-type titanium peroxide dispersion was obtained.
When the silica concentration is 50 ppm, it is a light yellow fine suspension, 140 ppm is slightly darker yellow and transparent than 50 ppm, 250 ppm is slightly darker yellow and transparent than 140 ppm, and 410 ppm is 250 ppm In the case of 3830 ppm, it was slightly dark yellow and highly transparent than in the case of 410 ppm.
The anatase-type titanium peroxide dispersion having each silica concentration was subjected to a long-term storage test and a heating test in a cool and dark place in the same manner as in Example 1. However, as in Example 1, there was no discoloration and formation of precipitates. There was no change in properties.

The anatase-type titanium peroxide dispersion prepared in Comparative Example 1 was suspended in a pale yellow color as described above.
In addition, the titanium peroxide dispersion obtained in Comparative Example 2 is a pale yellow with suspension when the NH ₄ ⁺ concentration is 120 ppm and 300 ppm, clear yellow when the concentration is 500 ppm, and 500 ppm when the concentration is 10000 ppm. As in the case of, it was yellow and transparent.
In each of these cases, as in Examples 1 and 2, a long-term storage test was conducted in a cool and dark place. Only 500 ppm was clear and unchanged in yellow, but in other cases, white precipitation was observed at 100 ppm, and suspension was observed at 300 ppm. In the case of a certain pale yellow color and 1000 ppm, it changed to a viscous and suspendable one.

As described above, the photocatalyst film-forming aqueous liquid of the present invention is characterized in that it comprises an anatase-type titanium oxide fine particle dispersion having a peroxo group containing a silicon compound such as silica sol. In the invention, when the dispersion contains a silicon compound such as silica sol, an aqueous liquid for forming a photocatalyst film having excellent transparency and stability over time can be obtained.

The 1st manufacturing method which is one aspect | mode of the method of manufacturing the aqueous solution for photocatalyst film formation of this invention is shown.

Claims (7)

An aqueous liquid for forming a photocatalyst film excellent in transparency and stability, comprising an anatase-type titanium peroxide fine particle dispersion having a peroxo group containing a silicon compound. The water solution for forming a photocatalyst film according to claim 1, wherein the silicon compound is silica sol, alkali silicate, or alkali borosilicate. The aqueous liquid for forming a photocatalyst film according to claim 1 or 2, wherein silicon in the silicon compound is contained in an amount of 0.005 to 50 wt% with respect to titanium oxide. A tetravalent titanium salt solution and an aqueous ammonia solution are reacted to form titanium hydroxide, which is peroxylated with an oxidant, thereby forming ultra-fine particles of amorphous titanium peroxide. Further, a method for producing a water solution for forming a photocatalyst film excellent in transparency and stability, characterized in that it is transferred to anatase-type titanium peroxide by further heat treatment, and a silicon compound is mixed in any of these processes. Peroxidation of a tetravalent titanium salt solution with an oxidizing agent and reaction with an aqueous ammonia solution to form a hydroxide to form an ultra-fine particle amorphous titanium peroxide, followed by heat treatment, anatase A method for producing a water solution for forming a photocatalyst film excellent in transparency and stability, characterized in that it is transferred to type titanium peroxide and a silicon compound is mixed in any of these processes. Metallic titanium powder or titanium oxide powder is reacted with hydrogen peroxide and aqueous ammonia solution to form titanium hydroxide and peroxo group at the same time to form ultra-fine particles of amorphous titanium peroxide. A method for producing a water solution for forming a photocatalyst film excellent in transparency and stability, characterized in that it is transferred to anatase-type titanium peroxide by further heat treatment, and a silicon compound is mixed in any of these processes. A coating film is formed by coating an aqueous solution for forming a photocatalyst film, which is composed of a dispersion of fine particles of anatase-type titanium peroxide having a peroxo group containing a silicon compound, with excellent transparency and stability on a substrate surface. A method for producing a structure having a photocatalytic coating on its surface.

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