JP2006312730A - Composition for forming photocatalyst coating film of titanium oxide, its manufacturing method, coating film for photocatalyst and coated article for photocatalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for forming a coating film that contains titanium oxide powders and exhibits high photoabsorption characteristics in a visible light region, its manufacturing method, a coating film for a photocatalyst, obtained when this is applied on a substrate, that excels in hardness and adhesion, and a coated article for a photocatalyst. <P>SOLUTION: There are provided the composition for forming the titanium oxide photocatalyst coating film that contains sulfur-containing titanium oxide powders, an organosilane compound and a dispersion medium, its manufacturing method, the coating film for the photocatalyst that is obtained by applying the coating film-forming composition on the substrate, and the coated article for the photocatalyst. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a composition for forming a photocatalytic coating film (hereinafter simply referred to as “coating film forming composition”) in which a titanium oxide photocatalyst dispersed with a visible light responsive type photocatalytic activity and high in harmful substance decomposition and wet solar cells is effective. ), Its production method, photocatalyst coating film and photocatalyst coating material.

  Titanium oxide powder has long been used as a white pigment, and in recent years, it has been widely used in sintered materials used in electronic materials such as UV shielding materials for cosmetics, photocatalysts, capacitors, thermistors, and barium titanate materials. Has been. In particular, there have been many attempts to use it as a photocatalyst for several years. Titanium oxide is excited by irradiating titanium oxide with light having energy higher than its band gap, and electrons are generated in the conduction band. Holes are generated in the electric band, and development of applications for photocatalytic reactions using the reducing power of electrons or the oxidizing power of holes has been actively conducted. This titanium oxide photocatalyst has a wide variety of uses. Generation of hydrogen by water decomposition, synthesis of organic compounds using redox reaction, exhaust gas treatment, air purification, deodorization, sterilization, antibacterial, water treatment, lighting. Numerous applications have been developed, such as preventing contamination of equipment.

  However, since titanium oxide exhibits a large refractive index in the wavelength region near visible light, light absorption hardly occurs in the visible light region. This is because anatase-type titanium dioxide has a band gap of 3.2 eV and rutile-type titanium dioxide has a band gap of 3.0 eV. The wavelength of light that can be absorbed by titanium oxide is 385 nm or less for anatase-type titanium oxide. The rutile type titanium oxide has a thickness of 415 nm or less. Most of the light of these wavelengths falls in the ultraviolet region, and only a small portion is contained in infinite sunlight on the earth. Conventionally known titanium oxide photocatalysts are photocatalysts under ultraviolet irradiation. Although it exhibits the characteristics, only a part of its energy can be used under sunlight, and sufficient activity as a photocatalyst cannot be expected. Also, considering the use under fluorescent lamps indoors, since the spectrum of fluorescent lamps is almost 400 nm or more, sufficient characteristics as a photocatalyst cannot be expressed. In view of this, development of highly active photocatalysts that exhibit catalytic activity in the visible light region and have higher utility is being carried out.

For example, in Patent Document 1 (Japanese Patent Laid-Open No. 9-262482), one or more kinds of metal ions selected from the group consisting of Cr, V, Cu, Fe, Mg, Ag, Pd, Ni, Mn, and Pt are included. A photocatalyst containing titanium oxide from the surface at a rate of 1 × 10 ¹⁵ ions / g-TiO ₂ or more is disclosed, and ions of these metals are accelerated to high energy of 30 KeV or more to form titanium oxide. Irradiation introduces the metal ions into titanium oxide. Moreover, in patent document 2 (Unexamined-Japanese-Patent No. 11-290697), the process which hold | maintains the solid containing a transition metal and the titanium oxide by which the said transition metal is doped in a vacuum chamber, and a metal inside the said vacuum chamber A photocatalytic titanium oxide doped with the transition metal by generating plasma and irradiating the generated metal plasma is disclosed. However, these inventions must use a very special apparatus such as accelerating metal ions to high energy and generating metal plasma in order to dope metal ions into titanium oxide. Not suitable for manufacturing.

  In order to solve such a problem, Patent Document 3 (Japanese Patent Laid-Open No. 12-237598) discloses that B, P, and Ti, which are components different from the constituent components of the semiconductor, are formed on the surface of a semiconductor such as titanium oxide. , V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, W, Pt, Hg, Pb, Bi, Pr Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and a medium containing at least one cation selected from the group consisting of Lu, and contact with the semiconductor A method for producing a visible light responsive photocatalyst comprising a first step of containing a cation and a second step of heating the semiconductor containing the cation in a reducing atmosphere is disclosed. . However, the photocatalyst doped with metal ions in titanium oxide by such a method does not necessarily have sufficient catalytic activity, and further improvement has been desired.

  In addition to the photocatalyst in which titanium ions are doped with metal ions such as transition metals as described above to exhibit catalytic activity in the visible light region, in Patent Document 4 (WO 01/010552), oxygen sites of titanium oxide crystals are disclosed. Titanium oxide by either substituting part of it with nitrogen atoms, doping nitrogen atoms between the lattices of titanium oxide crystals, or doping nitrogen atoms into the crystal grain boundaries of titanium oxide, or a combination thereof A photocatalytic substance containing a nitrogen atom in a crystal and a photocatalytic substance exhibiting a photocatalytic action in the visible light region having a Ti—O—N structure in which a titanium oxide crystal contains nitrogen is disclosed. As a method for obtaining such a photocatalytic substance, sputtering of titanium oxide in a nitrogen gas atmosphere is mentioned. However, the production cost is high and it is difficult to produce on an industrial scale. Moreover, although there is also a disclosure of a simple method of firing titanium oxide in an ammonia atmosphere, nitrogen atoms are not sufficiently doped in titanium oxide, and the resulting photocatalyst is not sufficiently catalytic.

  On the other hand, when titanium oxide is used as a photocatalyst as described above, it is suspended and dispersed in a dispersion medium such as water or an organic solvent to prepare a coating agent or paint, which is applied to a substrate and dried, and then oxidized for photocatalyst. Form a titanium coating. In this case, the dispersibility of the titanium oxide powder in the solvent becomes a problem. Specifically, after the titanium oxide powder is dispersed in the solvent, the titanium oxide powder aggregates and precipitates.

  In order to solve such a problem relating to the dispersibility of the titanium oxide powder, a method of coating the surface of the titanium oxide powder with a hydrophobic material having high dispersibility such as silica and alumina is known. (JP-A-5-281726) adjusts the pH of an aluminum basic salt aqueous solution to 10.5 to 12.0 with an acid, mixes it with a titanium dioxide slurry, and then neutralizes it with an acid. A method for uniformly depositing aluminum oxide hydrate on the surface of titanium dioxide powder is disclosed. Moreover, in patent document 6 (Unexamined-Japanese-Patent No. 2001-220141) and patent document 7 (Unexamined-Japanese-Patent No. 2001-262005), the titanium oxide dispersion formed by uniformly disperse | distributing a titanium oxide powder to a peroxotitanic acid containing dispersion medium. Alternatively, a composition for forming a coating film for a titanium oxide photocatalyst is disclosed.

  However, these titanium oxide photocatalyst coating film-forming compositions have improved dispersibility of the titanium oxide powder in the dispersion medium, but the titanium oxide photocatalyst coating film-forming composition is formed using the titanium oxide photocatalyst coating film-forming composition. There was a problem that when the base material coated with the titanium oxide coating film was processed, the coating film was peeled off because the hardness and adhesion of the film were low.

WO98 / 03607 includes (a) photocatalyst particles made of metal oxide, (b) silica fine particles, a silicone resin film precursor capable of forming a silicone resin film, and a silica film precursor capable of forming a silica film. A composition containing at least one selected from the group consisting of (c) a solvent is disclosed. Moreover, hydrolyzable silane derivatives can be used as the component (b) of this composition, and it is described that the titanium oxide photocatalyst particles are immobilized on the substrate surface. However, this titanium oxide photocatalyst coating film-forming composition does not have sufficient dispersibility and gives a coated film with high antifogging properties and hardness to the substrate after coating. There is no description about the adhesiveness and smoothness of the coating film. Moreover, these prior documents do not disclose a composition for forming a photocatalyst coating film using the sulfur-containing titanium oxide powder used in the present invention.
JP-A-9-262482 JP-A-11-290697 JP-A-12-237598 WO 01/010552 Publication JP-A-5-281726 JP 2001-220141 A JP 2001-262005 A WO 98/03607

  Accordingly, an object of the present invention is to provide a coating film-forming composition containing a titanium oxide powder that exhibits high light absorption characteristics in the visible light region, a method for producing the same, and excellent hardness and adhesion when applied to a substrate. It is providing the coating film for photocatalysts, and the coating material for photocatalysts.

  Under such circumstances, the present inventors have conducted extensive studies, and as a result, a composition for forming a titanium oxide photocatalyst coating film containing a sulfur-containing titanium oxide powder, an organosilane compound, peroxotitanic acid and a dispersion medium in a specific blending ratio. It has been found that a coating film obtained by applying an article to a substrate is excellent in hardness and adhesion, and exhibits high light absorption characteristics in the visible light region, and has completed the present invention.

  That is, the present invention contains a sulfur-containing titanium oxide powder, an organosilane compound, peroxotitanic acid and a dispersion medium, and the compounding amount of the organosilane compound is based on mass in the composition for forming a titanium oxide photocatalyst coating film. The total concentration of peroxotitanic acid is 0.37 to 2.2 times the total concentration of titanium oxide, and is 30% or more and 99% or less of the total concentration with peroxotitanic acid. A titanium oxide photocatalyst coating composition is provided.

  The present invention also includes a sulfur-containing titanium oxide powder, an organosilane compound, peroxotitanic acid, an alkane sulfonate, and a dispersion medium, and the content of the alkane sulfonate is for forming the titanium oxide photocatalyst coating film. The present invention provides a composition for forming a titanium oxide photocatalyst coating film, which is 0.04 to 0.4% by mass in the composition.

  The present invention also provides a titanium oxide photocatalyst coating composition characterized by obtaining a composition for forming a titanium oxide photocatalyst coating film by dispersing a sulfur-containing titanium oxide powder, an organosilane compound and peroxotitanic acid in a dispersion medium. A method for producing a film-forming composition is provided. Moreover, this invention provides the coating film for photocatalysts obtained by apply | coating the said composition for titanium oxide photocatalyst coating film formation to a base material, and drying, Moreover, this invention is for the said titanium oxide photocatalyst coating film formation. The present invention provides a coated product for a photocatalyst obtained by coating a composition on a substrate and drying it.

  The photocatalyst coating film obtained by applying the composition for forming a titanium oxide photocatalyst coating film of the present invention to a substrate is excellent in hardness and adhesion, does not easily peel off, and has a high light absorption property in the visible light region. To express.

  The sulfur-containing titanium oxide powder used in the composition for forming a titanium oxide photocatalyst coating film of the present invention is not particularly limited. In addition to those containing a sulfur atom in titanium oxide, the sulfur atom is a titanium atom in titanium oxide. And those doped in titanium oxide as cations. As a method for obtaining such a sulfur-containing titanium oxide powder, rutile or anatase type titanium oxide obtained by reacting titanium tetrachloride with oxygen or, if necessary, a combustible gas such as hydrogen gas or water vapor in a gas phase. Oxide and sulfur or sulfur-containing compound mixed and baked, titanyl sulfate, titanium sulfate and ammonium ammonium sulfate baked method, titanium oxide obtained by hydrolyzing titanium-containing aqueous solution such as titanyl sulfate, titanium sulfate and titanium ammonium sulfate A method of mixing and baking sulfur and a sulfur-containing compound, a method of mixing and baking titanium oxide obtained by hydrolyzing an organic titanium compound such as titanium alkoxide and a sulfur or sulfur-containing compound, and a solution or alkali of a titanium chloride aqueous solution In this stage, sulfur or By mixing sulfur compounds, and then and a method of firing a solid containing sulfur or sulfur-containing compounds. Of these, when obtaining a solid by hydrolyzing or neutralizing an aqueous solution of titanium chloride with alkali, sulfur or a sulfur-containing compound is mixed in any of these stages, and then the solid containing sulfur or the sulfur-containing compound is calcined. The sulfur-containing titanium oxide powder obtained by the method (hereinafter, also simply referred to as “method using a titanium chloride aqueous solution”) is preferable in that when it is used as a photocatalyst, photocatalytic activity is exhibited in the visible light region. Hereinafter, the method using the titanium chloride aqueous solution will be described in detail.

  The titanium chloride aqueous solution is a titanium trichloride aqueous solution or a titanium tetrachloride aqueous solution. The aqueous titanium trichloride solution can be obtained, for example, by dissolving titanium metal in hydrochloric acid. As the metal titanium, titanium powder, sponge-like titanium, or titanium scrap such as chips are used. The titanium tetrachloride aqueous solution can be obtained by dissolving titanium tetrachloride in water or hydrochloric acid. The titanium concentration in the aqueous titanium chloride solution is arbitrary, but considering the production efficiency and the particle size of the resulting titanium oxide powder, the titanium content is 1 to 20% by mass, preferably 1 to 10% by mass, particularly preferably 2 ˜5 mass%. In addition, it is desirable that the aqueous solution of titanium chloride has few impurity components and high purity. Specifically, aluminum, iron, and vanadium are each 1 ppm or less, and silicon and tin are each 10 ppm or less.

  The titanium chloride aqueous solution is hydrolyzed or neutralized with an alkali to obtain a solid, which is a rutile or anatase titanium oxide, orthotitanic acid, metatitanic acid, titanium hydroxide or titanium oxide water. Japanese and powdery or colloidal. Moreover, this solid substance is the same crystal | crystallization and form also when it contains sulfur or a sulfur compound. Specific examples of the method for obtaining such a solid material include the following methods.

(1) A method in which an aqueous titanium chloride solution is heated under reflux and hydrolyzed to precipitate a solid. Chlorine gas is generated at this time, but more fine titanium oxide powder can be obtained by suppressing the generation of hydrochloric acid gas by pressurizing or refluxing and hydrolyzing in a low pH region.
(2) A method in which an alkali such as ammonia is added to an aqueous titanium chloride solution to precipitate a solid. At this time, it is desirable to neutralize with ammonia or aqueous ammonia containing no metal component among these alkalis.
(3) A method in which a titanium chloride aqueous solution is added to an alkaline solution such as aqueous ammonia to precipitate a solid.

  After obtaining by hydrolyzing or neutralizing the aqueous titanium chloride solution as described above, orthotitanic acid or metatitanic acid is produced. In order to improve the photocatalytic activity, titanium chloride is produced under the conditions that metatitanic acid is produced. It is desirable to hydrolyze or neutralize the aqueous solution. Thereafter, washing is performed to remove impurities such as hydrochloric acid and alkali components, and separation and drying are performed as necessary to form powder. Further, drying is performed as necessary to remove water such as crystal water. The solids are separated by filtration, decantation, centrifugation, or the like using a filter or filter press, and drying is preferably a method that can prevent aggregation of solid particles, and a spray dryer or a commercial dryer is used. Moreover, the obtained solid may be mixed with sulfur or a sulfur-containing compound in a suspended state without being dried, or may be subjected to a firing step.

Titanium oxide powder obtained by neutralizing an aqueous titanium chloride solution with a hydroxide of an alkali metal such as NaOH, KOH, Ca (OH) ₂ (slaked lime), or a metal such as an alkaline earth metal in the method of (2) above Even if these metal components remain, the properties of the photocatalyst finally obtained are not significantly affected. For example, a slaked lime solution is added to a titanium chloride aqueous solution and neutralized to precipitate titanium oxide hydrate, and a flocculant such as polyaluminum chloride is added to the suspension to precipitate and separate solids. Such a method is a process generally used for wastewater treatment such as acidic water, and it becomes possible to produce titanium oxide powder very efficiently on an industrial scale.

  In addition, by hydrolyzing an aqueous titanium chloride solution in the presence of ammonium sulfate to obtain a solid, it is possible to improve performance such as the activity of the finally obtained titanium oxide photocatalyst. Furthermore, the performance of the titanium oxide photocatalyst finally obtained can be improved also by hydrolyzing an aqueous titanium chloride solution in the presence of ammonium sulfate and then neutralizing with ammonia to obtain a solid.

Furthermore, the crystal form of the titanium oxide of the finally obtained sulfur-containing titanium oxide powder can be controlled at the time of obtaining a solid by neutralizing or hydrolyzing the aqueous titanium chloride solution. The crystal form of titanium oxide is a rutile type, anatase type, or a mixed crystal thereof, and the crystal type (rutile ratio) of titanium oxide is controlled according to the use of the photocatalyst. The rutile ratio of the obtained titanium oxide powder can be controlled by the time or speed of hydrolysis or neutralization with the alkali of the above titanium chloride aqueous solution. For example, when neutralizing titanium tetrachloride aqueous solution with aqueous ammonia, etc., neutralization in a short time will yield titanium oxide with a low anatase-rich rutile ratio, and slowing the rate of neutralization will result in an oxidation with a high rutile ratio. Titanium can be obtained. The neutralization rate is preferably 50 to 500 g, more preferably 100 to 300 g, per minute in terms of titanium atoms. When it is slower than the rate of neutralizing 200 g of titanium atoms per minute, the rutile ratio becomes 50% or more. In addition, the rutile ratio of titanium oxide obtained can be controlled by the pH of the reaction system when neutralizing or hydrolyzing the titanium chloride aqueous solution. For example, after titanium oxide powder is precipitated, the ripening reaction is carried out in a low pH atmosphere. The rate is improved, and a rutile type and anatase type mixed crystal can be obtained.
The solid material obtained as described above can control the average particle diameter, specific surface area, and crystal form depending on the conditions of hydrolysis or neutralization with alkali, but in order to improve the activity of the photocatalyst, A larger surface area is preferred. Specifically ^{50 m} 2 / g or more in BET specific surface area is preferably 100 m ² / g or more, particularly preferably 150 to 300 m ² / g. The crystal form is preferably a rutile type, anatase type, or a mixed crystal of rutile type and anatase type, and a fine titanium oxide having a specific surface area of 50 m ² / g or more.

  Any of the steps of mixing sulfur or a sulfur-containing compound may be any of a step before preparing the solid, a step of precipitating the solid, or a step after precipitating the solid, Mixing with the titanium chloride aqueous solution as a raw material or mixing with a precipitated solid is desirable.

  The sulfur-containing compound used in the method using the titanium chloride aqueous solution is preferably a liquid or solid compound at room temperature, and examples thereof include a sulfur-containing inorganic compound, a sulfur-containing organic compound, and a metal sulfide. Specific examples include thioethers, thioureas, thioamides, thioalcohols, thioaldehydes, thiazyl, mercaptals, thiols, and thiocyanates. Specific compounds include thiourea and dimethylthiourea. , Sulfoacetic acid, thiophenol, thiophene, benzothiophene, dibenzothiophene, thiobenzophenone, bithiophene, phenothiazine, sulfolane, thiazine, thiazole, thiadiazole, thiazoline, thiazolidine, thianthrene, thiane, thioacetanilide, thioacetamide, thiobenzamide, thioanisole, Thionine, methylthiol, thioether, thiocyan, sulfuric acid, sulfonic acids, sulfonium salts, sulfonamides, sulfinic acids, sulfoxides, sulfines, sulfines Such as § emission class, and the like. These compounds can be used alone or in combination of two or more.

  Of these, sulfur-containing organic compounds are preferred, and organic compounds containing no sulfur and nitrogen atoms are particularly preferred. Specifically, thiourea and dimethylthiourea are preferred.

In the method using an aqueous titanium chloride solution, specific examples of the method for forming a mixture of solid and sulfur or a sulfur-containing compound include the following methods.
(1) A method in which sulfur or a sulfur-containing compound is mixed with an aqueous titanium chloride solution and then hydrolyzed or neutralized with an alkali to obtain a mixture of a solid and sulfur or a sulfur-containing compound,
(2) A method of obtaining a mixture by hydrolyzing or neutralizing an aqueous solution of titanium chloride with an alkali and then mixing the solid with sulfur or a sulfur-containing compound,
(3) A method in which a titanium chloride aqueous solution is hydrolyzed or neutralized with an alkali to obtain a solid, the obtained solid is calcined, and then the solid and sulfur or a sulfur-containing compound are mixed to obtain a mixture;
(4) After mixing sulfur or a sulfur-containing compound with an aqueous titanium chloride solution and then neutralizing with hydrolysis or alkali to form a solid, further mixing sulfur or a sulfur-containing compound with the solid to obtain a solid Examples thereof include a method for obtaining a mixture of sulfur or a sulfur-containing compound.

  The amount of sulfur or sulfur-containing compound to be mixed with the solid used in the method using the aqueous titanium chloride solution is usually 1% by mass or more, preferably 5% by mass or more, based on the solid when converted to the mass of sulfur atoms. More preferably, it is 10-30 mass%. If the amount of sulfur or sulfur-containing compound mixed is small, the amount of sulfur atoms contained in the photocatalytic titanium oxide will eventually decrease, and sufficient visible light absorption will not occur.

  Sulfur or a sulfur-containing compound may be mixed as it is in a solid or liquid form, but may be dissolved or suspended in a solvent such as pure water or alcohol. In this case, the sulfur or sulfur-containing compound may be mixed. As a result, it is possible to obtain a sulfur-containing titanium oxide powder having a good performance in which it is uniformly dispersed in a solid substance and sulfur atoms are uniformly doped in titanium oxide.

  Next, a mixture of the solid material obtained above and sulfur or a sulfur-containing compound is calcined to form a titanium oxide photocatalyst. The calcining temperature is 200 to 800 ° C., preferably 300 to 600 ° C., more preferably 400 to 500 ° C. It is. When a sulfur-containing organic compound is used, the reaction is performed at a temperature at which the compound is decomposed and sulfur atoms are liberated to replace titanium atoms in the solid. The firing atmosphere is performed in an oxidizing atmosphere such as air or oxygen, a reducing atmosphere such as hydrogen gas or ammonia gas, an inert atmosphere such as nitrogen gas or argon gas, or under vacuum. Of these, the photocatalytic activity in the visible light region is preferably improved by carrying out in a reducing atmosphere such as hydrogen gas. Although only a reducing gas such as hydrogen gas may be used, firing in an atmosphere of a mixed gas of hydrogen and oxygen or a mixed gas of hydrogen, oxygen and inert gas is also effective. Furthermore, it is important to maintain the firing atmosphere so that the partial pressure of the sulfur component is maintained to some extent so that sulfur does not evaporate during the firing or the sulfur-containing compound decomposes and the sulfur component is not discharged from the firing furnace. When a by-product gas such as carbon dioxide gas is generated by decomposition during firing, such as a sulfur-containing organic compound having a carbon atom, it is better to exhaust from the firing atmosphere to some extent. Therefore, the container for firing is not completely open or sealed, and the upper part is opened so that a certain amount of pressure is applied and the by-product gas can be discharged, and a non-fixed lid is placed on the upper part. A cylindrical, dished or rectangular container provided is preferred.

  The sulfur-containing titanium oxide powder obtained as described above is washed as necessary to remove free sulfur components and others. Moreover, in order to improve the dispersibility of particle | grains, it can also surface-treat with surfactant etc.

The sulfur-containing titanium oxide powder obtained as described above is a pale yellow or yellow powder containing sulfur atoms in the titanium oxide, and the sulfur atoms are substituted with titanium atoms in the titanium oxide. And those doped in titanium oxide as cations. Specifically, it can be represented by the chemical formula Ti _1-x S _x O ₂ , and x, which is the content of sulfur atoms with respect to titanium atoms, is 0.0001 or more, preferably 0.0005 or more, more preferably 0.001. ~ 0.008. The sulfur atoms include not only those contained in titanium oxide as cations, but also those adsorbed on the surface of titanium oxide particles as sulfur oxides or sulfur molecules, and those contained in the crystal grain boundaries of titanium oxide. The sulfur component finally contained in the titanium oxide photocatalyst is 0.01 mass% or more, preferably 0.01 to 3 mass%, particularly preferably 0.03 to 1 mass% as sulfur atoms. The average particle size is 5 to 50 nm in terms of the primary particle size as observed by SEM photographic image, and the BET specific surface area is 100 to 250 m ² / g.

  Further, the sulfur-containing titanium oxide powder is excellent in visible light absorption characteristics, and an ultraviolet-visible diffuse reflection spectrum is measured, and an integrated value of absorbance at a wavelength of 300 to 350 nm is set to 1, usually, a wavelength of 350 to 400 nm. The integrated value of the absorbance at 0.3 to 0.9 and the integrated value of the absorbance at the wavelength of 400 to 500 nm is 0.3 to 0.9, and preferably the integrated value of the absorbance at the wavelength of 350 to 400 nm is 0. The integrated value of absorbance at a wavelength of 400 to 500 nm is 0.4 to 0.8, and more preferably, the integrated value of absorbance at a wavelength of 350 to 400 nm is 0.5 to 0.00. 7 and the integrated value of the absorbance at a wavelength of 400 to 500 nm is 0.5 to 0.75.

  In the sulfur-containing titanium oxide powder, the titanium oxide is a rutile type, anatase type, or a mixed crystal of a rutile type and an anatase type, and contains a sulfur atom, preferably a mixed crystal of a rutile type and an anatase type. The rutile ratio of titanium oxide is 5 to 99%, preferably 20 to 80%, more preferably 30 to 70%. The sulfur-containing titanium oxide powder is a mixed crystal of rutile type and anatase type, but may also contain amorphous titanium oxide.

  The measurement method of the rutile ratio is the peak area (Ir) of the strongest interference line (surface index 110) of the rutile crystalline titanium oxide in the X-ray diffraction pattern according to ASTM D 3720-84, and the strongest interference line of the titanium oxide powder ( The peak area (Ia) of the plane index 101) can be obtained and obtained from the following formula.

Rutile conversion rate (mass%) = 100-100 / (1 + 1.2 × Ir / Ia)
In the formula, the peak area (Ir) and the peak area (Ia) refer to the area of the portion protruding from the base line in the corresponding diffraction line of the X-ray diffraction spectrum, and the calculation method may be performed by a known method. It can be obtained by methods such as computer calculation and approximate triangulation.

  In the present invention, the content of the sulfur-containing titanium oxide may be appropriately adjusted according to the use, but in consideration of the transparency of the obtained titanium oxide coating film, it is 0.8 in the coating film forming composition. It is preferable that it is -20 mass%, Preferably it is 1.0-20 mass%. When the concentration of the sulfur-containing titanium oxide powder is less than 0.8% by mass, the photocatalytic performance cannot be exhibited sufficiently. On the other hand, when the concentration of the sulfur-containing titanium oxide powder exceeds 20% by mass, the dispersibility of the titanium oxide in the dispersion medium decreases.

  The organosilane compound used in the coating film-forming composition of the present invention is used to increase the hardness of the coating film. Examples of organosilane compounds include organosilanes and hydrolysates of organosilane compounds. As the organosilane, alkylalkoxysilane, alkoxysilane, oligomers or polymers thereof are used.

Examples of the organosilane compound include the following general formula (1);
R ¹ _x Si (OR ² ) _4-x (1)
(In the formula, R ¹ represents a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, a phenyl group, a vinyl group, an allyl group, in any of the aralkyl group may be the same or different, R ² Represents an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group, a phenyl group, a vinyl group, an allyl group, and an aralkyl group, which may be the same or different, and x is an integer of 0 ≦ x ≦ 3. General formula (2);

(Wherein R ³ and R ⁴ are an alkyl group having 1 to 6 carbon atoms, an alkoxy group, a hydroxyl group or a halogen atom selected from a chlorine atom, a bromine atom and a fluorine atom, and R ³ and R ⁴ are the same or different. R ⁵ and R ⁶ are each an alkyl group having 1 to 6 carbon atoms, R ⁵ and R ⁶ are the same or different, and m is the number of repetitions and is 2 to 20. It can be illustrated.

  Specific examples of organosilane compounds include tetraalkoxysilane, tetraacetyloxysilane, tetraphenoxysilane, vinyltriethoxysilane, and chlorotriethoxysilane. Tetraalkoxysilane includes tetraethoxysilane, tetramethoxysilane, and the like. Silane, trimethoxyethoxysilane and the like are preferable, and tetraethoxysilane is particularly preferable. As the hydrolyzate of organosilane, for example, a product obtained by adding and stirring organosilane in an aqueous solvent adjusted to pH 1 to 4 can be used. As the hydrolyzate of organosilane, a hydrolyzate of tetraethoxysilane is suitable.

  The dispersion medium used in the coating film forming composition of the present invention is not particularly limited, and examples thereof include water and organic solvents. Examples of the organic solvent include alcohols and ketones such as methanol, ethanol, and isopropanol. Of these, water is preferred. A dispersion medium can be used 1 type or in mixture of 2 or more types. When the dispersion medium is water, a commercially available aqueous peroxotitanic acid solution can be used as it is.

  In the coating film-forming composition of the present invention, the amount of the organosilane compound is 0.37 to 0.37 in terms of the total concentration of peroxotitanic acid with respect to the titanium oxide concentration on the mass basis in the coating film-forming composition. 2.2 times and 30% or more and 99% or less of the total concentration with peroxotitanic acid. When the total concentration with peroxotitanic acid is less than 0.37 times and less than 30% with respect to the total concentration with peroxotitanic acid, the hardness of the coating film is lowered. On the other hand, when it exceeds 2.2 times, the coating film surface is cracked and the smoothness is impaired.

In the composition for forming a coating film of the present invention, peroxotitanic acid is used for suppressing aggregation of the sulfur-containing titanium oxide powder, improving dispersibility, and increasing the hardness of the coating film. Peroxotitanic acid is also called peroxytitanic acid or titanium peroxide, and its structure is represented by H ₄ TiO ₅ , Ti (OOH) (OH) ₃ or TiO ₃ .2H ₂ O. Peroxotitanic acid is usually handled as a yellow, yellow-brown or red-brown transparent viscous aqueous solution (sol solution), and in the case of an aqueous solution, its pH is 5 to 8 and is almost in the neutral region. The peroxotitanic acid can use what is marketed, for example, "PTA-85" and "PTA-170" (all are peroxotitanic acid aqueous solution by the Sakai Corporation). It can also be prepared by a known method. For example, an aqueous solution of titanium tetrachloride is hydrolyzed with ammonia water to produce a slurry containing titanium hydroxide, which is washed and then added with hydrogen peroxide. A peroxytitanic acid aqueous solution can be obtained. Although it does not restrict | limit especially as a solvent of a peroxotitanic acid solution, For example, water and alcohols, such as ethanol and methanol, are mentioned, Among these, water is preferable. When using a peroxotitanic acid aqueous solution, a commercially available peroxotitanic acid aqueous solution can be used as it is. The concentration of the peroxotitanic acid solution to be used is appropriately determined depending on the addition concentration of the sulfur-containing titanium oxide powder, the use of the titanium oxide photocatalyst coating solution, and the like. Peroxotitanic acid is meant to include its salts or complexes with chelating agents. Examples of peroxotitanate include ammonium peroxotitanate, sodium peroxotitanate, potassium peroxotitanate, magnesium peroxotitanate, and calcium peroxotitanate. Examples of the complex with the chelating agent include a complex of the above-mentioned salt of peroxotitanic acid with a chelating agent such as tartaric acid and citric acid, and specifically, titanium peroxocitrate ammonium and the like.

  In the coating film forming composition of the present invention, the total concentration of the peroxotitanic acid and the organosilane compound is preferably 0.6 to 3.4% by mass. The mass ratio of the peroxotitanic acid to the organosilane compound is 1:99 to 70: peroxotitanic acid: organosilane compound from the hardness, adhesion, and smoothness of the coating surface. 30, preferably 3:97 to 70:30.

  The composition for forming a coating film of the present invention may optionally contain a dispersing agent other than peroxytitanic acid as an optional component. As the dispersing agent, one or two of polycarboxylate, polymer polycarboxylate, polyoxyethylene mono- or dialkyl ether, polyoxyethylene secondary alcohol ether, polyoxyethylene alkylphenyl ether, polyoxyethylene sterol ether It is preferable to use more than one species. Specific examples include sodium polyacrylate, ammonium polyacrylate, polymeric polyacrylate amine salt, polyoxyethylene distyrenated phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, and the like. In particular, ammonium polyacrylate (for example, “Poise 532A”, “Poise 2100”; manufactured by Kao Corporation), polymer polyacrylate amine salt (for example, “HIPLAAD ED214”; manufactured by Enomoto Kasei Co., Ltd.) Is preferred. In addition, if a dispersing material is used in combination with peroxotitanic acid, the dispersibility of sulfur-containing titanium oxide powder can be further improved. The amount of the dispersing material is appropriately determined.

  The coating film-forming composition of the present invention may further contain a sulfonic acid type compound as an optional component. By blending the sulfonic acid type compound, adhesion to a substrate having a hydrophobic surface can be improved. Examples of the sulfonic acid type compound include dialkyl sulfosuccinate, alkane sulfonate, alpha olefin sulfonate, alkyl benzene sulfonate, naphthalene sulfonate-formaldehyde condensate, and alkyl naphthalene sulfonate. The addition amount is 0.04 to 0.4% by mass, preferably 0.04 to 0.2% by mass in the composition for forming a coating film. If the amount added is small, the effect of improving wettability cannot be obtained. On the other hand, if the amount added is large, the photocatalytic performance is adversely affected.

  The coating film-forming composition of the present invention can further contain one or more of sodium phosphate, potassium phosphate and sodium hexametaphosphate as optional components. Thereby, the dispersibility of the titanium oxide in the composition for coating-film formation can be improved, and gelatinization can be prevented. The blending amount of these phosphoric acid compounds is appropriately determined.

  In particular, the composition for forming a coating film of the present invention containing peroxotitanic acid is excellent in dispersibility of the sulfur-containing titanium oxide powder in the dispersion medium. For this reason, it does not aggregate for at least 24 hours at room temperature.

  Examples of the method for producing the composition for forming a titanium oxide photocatalyst coating film of the present invention include a method in which a sulfur-containing titanium oxide powder, an organosilane compound and peroxotitanic acid are dispersed in a dispersion medium. Further, if necessary, a dispersant other than peroxotitanic acid or a sulfonic acid type compound can be blended, and if necessary, one or more selected from sodium phosphate, potassium phosphate and sodium hexametaphosphate are added. It can also be blended. In particular, organosilane is added to a dispersion medium adjusted to pH 1 to 4, preferably 2 to 4 to obtain an organosilane hydrolyzate solution, and this is mixed with a peroxotitanic acid aqueous solution. A method of mixing the mixed solution is preferred.

  An example is shown below. First, tetraethoxysilane is added to pure water adjusted to pH 1 to 4, preferably 2 to 4 with an acid, and stirred and stirred for a whole day with a stirrer to prepare a tetraethoxysilane hydrolyzate aqueous solution. The acid can be adjusted with a mineral acid or an organic acid. Examples of the mineral acid include hydrochloric acid, sulfuric acid, nitric acid, and the like, and examples of the organic acid include acetic acid, phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, and the like. Among these, those that do not affect the obtained photocatalytic activity are preferred, and nitric acid or phosphoric acid is preferred. Furthermore, if one or more kinds of sodium phosphate, potassium phosphate and sodium hexametaphosphate are mixed with the above tetraethoxysilane hydrolyzate aqueous solution, it is finally mixed with a slurry containing sulfur-containing titanium oxide powder to form a coating film The effect of improving the dispersibility of titanium oxide and preventing gelation can be obtained when the composition is formed. On the other hand, the sulfur-containing titanium oxide powder is dispersed in a dispersion medium to obtain a slurry containing sulfur-containing titanium oxide powder. This is mixed with a peroxotitanic acid aqueous solution at a predetermined ratio to prepare a mixed aqueous solution of peroxotitanic acid and a slurry containing sulfur-containing titanium oxide powder. The method for dispersing the sulfur-containing titanium oxide powder-containing slurry and the peroxotitanic acid aqueous solution is not particularly limited, and the dispersion is performed using a known means such as high-speed stirring, shaking, bead mill, etc. can do. Further, when dispersing, wet pulverization can be performed by a ball mill, a jet mill or the like. The aqueous solution of the tetraethoxysilane hydrolyzate thus obtained and a slurry containing peroxotitanic acid and sulfur-containing titanium oxide can be mixed to obtain the composition for forming a titanium oxide photocatalyst coating film of the present invention.

  In addition, when dispersing the sulfur-containing titanium oxide powder in the dispersion medium, a dispersing material other than peroxytitanic acid can be used as appropriate. Examples of the dispersing material include those similar to those used in the composition for forming a titanium oxide photocatalyst coating film.

  Furthermore, a sulfonic acid type compound can be added to the dispersion of the organosilane compound. Thereby, when the surface of a base material is hydrophobic, adhesiveness with a board | substrate can be improved. The sulfonic acid type compound and the blending amount thereof are the same as those of the composition for forming a titanium oxide photocatalyst coating film. The sulfonic acid type compound is preferably an alkanesulfonic acid. When the sulfonic acid type compound is used after being dispersed in a dispersion liquid of sulfur-containing titanium oxide powder, the sulfur-containing titanium oxide powder in the dispersion liquid does not disperse well, which is not preferable.

  The titanium oxide photocatalyst coating film-forming composition is used to form the photocatalyst coating film of the present invention, and this coating film is formed by applying the composition to a substrate surface and drying it. The application method at this time may be a known method, and examples thereof include a spray coating method, a dip coating method, and a spin coating method. Next, after coating and drying, a titanium oxide film is formed. In the present invention, a coating film that is strong and has high photocatalytic activity can be formed by drying at room temperature to less than 100 ° C. without any special heat treatment. The Moreover, a firmer coating film can be formed also by heat-processing in the range of 100 degreeC-500 degreeC. The thickness of the coating is not particularly limited as long as the photocatalytic activity can be exhibited and the strength of the coating can be ensured, but is usually 0.1 to 10 μm, preferably 0.5 to 2 μm. .

  Examples of the substrate on which the photocatalyst coating composition of the present invention is applied include metals such as stainless steel, carbon steel, aluminum, and titanium, organic materials such as glass, concrete, asphalt, slate, stone, wood, fiber, and plastic, Any material can be used, including materials that are not corrosion resistant and materials that are not heat resistant in acidic regions such as paper. Also, a substrate whose surface is subjected to hydrophobic treatment may be used. Examples of the hydrophobic treatment include coating with a silicone-based water repellent treatment agent.

  The coating composition for coating titanium oxide photocatalyst of the present invention contains sulfur-containing titanium oxide having high activity as a photocatalyst, and also contains an organosilane compound, preferably peroxotitanic acid. When coated on tiles, mirrors, metals, lenses, etc., in addition to high photocatalytic activity, a photocatalytic coating film with high hardness and adhesion can be obtained. In addition, since the coating composition for applying a titanium oxide photocatalyst of the present invention provides a photocatalytic coating having excellent absorption characteristics in the visible light region, sunlight or a fluorescent lamp in a room can be used without an ultraviolet light source. The photocatalytic activity is sufficiently reproduced with a light source of. In addition, since the photocatalyst coating film is excellent in hardness and adhesion, it is very advantageous in that the photocatalyst coating film is not destroyed even if the coated substrate is processed. It can be widely applied as a photocatalyst coating for the purpose of deodorization, sterilization, antibacterial, water treatment, prevention of stains on lighting equipment, and the like.

EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, this is merely an example and does not limit the present invention.

Evaluation of the sulfur-containing titanium oxide photocatalyst obtained in the examples was carried out as follows.
(1) Measurement of sulfur content in sulfur-containing titanium oxide photocatalyst Field emission scanning electron microscope (Field Emission-SEM: FE-SEM) with energy dispersive X-ray fluorescence spectrometer (EDX) (Hitachi Electronic Scanning) Quantitative analysis of sulfur atoms in titanium oxide was performed with a microscope S-4700).

(2) Measurement of the rutile ratio The peak area (Ir) of the strongest interference line (surface index 110) of rutile crystalline titanium oxide and the strongest interference line of titanium oxide powder (in the X-ray diffraction pattern according to ASTM D 3720-84) The peak area (Ia) of the plane index 101) was obtained and obtained from the above formula. The X-ray diffraction measurement conditions are as follows.

(X-ray diffraction measurement conditions)
Diffraction device RAD-1C (manufactured by Rigaku Corporation)
X-ray tube Cu
Tube voltage / tube current 40kV, 30mA
Slit DS-SS: 1 degree, RS: 0.15mm
Monochromator graphite measurement interval 0.002 degree counting method Constant clock method (4) Decomposition performance of isopropyl alcohol (IPA) A glass flask with a 10 ml stirrer was charged with 5 ml of an acetonitrile solution of isopropyl alcohol having an initial concentration of 50 mmol / liter. This was charged with 0.1 g of a sulfur-containing titanium oxide photocatalyst powder, and irradiated with a light source obtained by cutting light of a wavelength of 410 nm or less with a filter while stirring, and after 1 hour, 2 hours and 5 hours, acetonitrile of isopropyl alcohol A small amount of the solution was collected, and the concentration of isopropyl alcohol was measured by gas chromatography. Degradation performance indicated the concentration at each time as a ratio (%) to the initial concentration.

(5) Decomposition performance of methylene blue (MB) A 150 ml glass flask equipped with a stirrer was charged with 100 ml of an aqueous methylene blue solution having an initial concentration of 50 μmol / liter, charged with 0.2 g of a sulfur-containing titanium oxide photocatalyst powder, and hydrochloric acid. The pH was adjusted to 3 with light shielding, and the mixture was left stirring for 12 hours or longer. A small amount of methylene blue aqueous solution was collected, and the concentration of methylene blue was measured with a spectrophotometer. Thereafter, a light source having a wavelength of 410 nm or less was cut with a filter while stirring, and a small amount of methylene blue solution was collected after 1 hour, 2 hours, and 5 hours, and the concentration of methylene blue was measured with a spectrophotometer. . Degradation performance indicated the concentration at each time as a ratio (%) to the initial concentration.

Reference example 1
(Production of sulfur-containing titanium oxide powder)
297 g of a titanium tetrachloride aqueous solution having a titanium concentration of 4 mass% was inserted into a 1000-ml round bottom flask equipped with a stirrer, and then heated to 60 ° C. Next, ammonia water was added instantaneously to maintain the pH of the reaction system at 7.4 for neutralization, and the mixture was kept at 60 ° C. for 1 hour to obtain a metatitanic acid solid. The obtained solid was filtered and washed with pure water, and 9.7 g of thiourea dissolved in 100 ml of pure water was added thereto and stirred for 30 minutes. Thereafter, the solid was dried at 60 ° C. and pulverized with a ball mill to obtain a mixture of titanium oxide powder and thiourea. The mixture was filled in an alumina crucible without a lid, and was charged in a firing furnace, and fired at 400 ° C. for 3 hours in air mixed with 3% by volume of hydrogen. Thereafter, it was pulverized by a ball mill, washed with pure water, and then dried at 60 ° C. to obtain a pale yellow titanium oxide photocatalyst. When the sulfur content in the obtained titanium oxide photocatalyst was measured, it was 0.25% by mass, the rutile ratio was 10%, and the specific surface area was 180 m ² / g. This sulfur-containing titanium oxide photocatalyst has a photocatalytic action in the visible light region and, as shown in Table 1, is excellent in the decomposition performance of organic substances such as IPA and MB.

Examples 1 to 13 and Comparative Examples 1 to 10
(Method for producing composition for forming titanium oxide photocatalyst coating film)
Tetraethoxysilane was added to an aqueous solution adjusted to pH 3 with nitric acid, and the mixture was stirred for a whole day and night with a stirrer to perform hydrolysis, thereby preparing a tetraethoxysilane hydrolyzate aqueous solution. On the other hand, with respect to pure water, the sulfur-containing titanium oxide powder obtained in Reference Example 1 was added at a predetermined ratio and dispersed to prepare a water slurry of the sulfur-containing titanium oxide powder. A peroxotitanic acid aqueous solution was added to the water slurry at a predetermined ratio, followed by treatment with a ball mill and a bead mill to prepare a mixed aqueous solution of peroxotitanic acid and a slurry containing sulfur-containing titanium oxide powder. The operation conditions of the ball mill were a media diameter of 10 mmφ, a rotation speed of 60 rpm, a grinding time of 16 hours, and the bead mill operation conditions were a media diameter of 0.03 to 0.1 mmφ, a peripheral speed of 6 to 8 m / sec, and an operation time of 2 hours. To this mixed aqueous solution, the tetraethoxysilane hydrolyzate aqueous solution was added and stirred to prepare a sulfur-containing titanium oxide photocatalyst coating composition (coating solution). Table 2 shows the sulfur-containing titanium oxide powder concentration in the coating liquid, the total concentration of peroxotitanic acid and tetraethoxysilane (hereinafter, solid content concentration), and the mixing ratio of peroxotitanic acid and tetraethoxysilane. Prepared. The coating liquids obtained in Examples 1 to 13 and Comparative Examples 1 to 10 were excellent in dispersibility without agglomeration after standing at room temperature for 24 hours. .

(Formation and evaluation of titanium oxide photocatalyst coating)
In Examples and Comparative Examples, a slide glass having a hydrophilic surface was dipped in the composition for forming a titanium oxide photocatalyst coating film, and then a titanium oxide photocatalyst coating film obtained by drying at room temperature for 24 hours was formed. The titanium oxide photocatalyst coating film was evaluated by measuring its hardness and adhesion. Hardness and adhesion were measured as follows. The results are shown in Tables 3 to 9.

(6) Pencil hardness test A pencil hardness test was performed according to JIS-K5400 (hand-drawing method), and tearing of the coating film was visually evaluated. ○ indicates no scratch, Δ indicates a slight scratch, and × indicates a clear scratch.
(7) Adhesion strength test An adhesion strength test was conducted in accordance with JIS-K5400 (tape peeling test). The glass slide coated with the photocatalyst coating is cut with a cutter knife in a grid pattern (10 × 10 = 100 squares), and the cellophane tape is attached, and then the cellophane tape is kept at a right angle to the coating surface and momentarily. It peeled off and the state of the damage | wound was observed visually, and the evaluation score (0-10) was attached. The evaluation score also conformed to JIS-K5400 (tape peeling test). For example, 10 is not peeled off at all, 8 is slightly peeled off at the intersection of cuts, there is no peeling at a glance, the area of the defect is within 5% of the total rectangular area, 2 is peeling due to cuts The width is wide, the area of the defect portion is within 35 to 65% of the total rectangular area, and 0 indicates the peeling area of 65% or more of the total rectangular area.

From Tables 3 and 4 in which the titanium oxide concentration was changed, the pencil hardness varies depending on the titanium oxide concentration even with the same solid content concentration and composition. The higher the titanium oxide concentration, the lower the pencil hardness of the coating film. The results of changing the solid content concentration at the same titanium oxide concentration (1.6% by mass) are shown in Tables 5 to 9. In Comparative Example 1 and Comparative Example 5 in which the tetraethoxysilane concentration was 0, a coating film having good pencil hardness could not be obtained. It can also be seen that the pencil hardness increases as the tetraethoxysilane concentration increases. In the case of Comparative Example 10 having a tetraethoxysilane concentration of 4.0% by mass, the pencil hardness and adhesion were good, but cracks were generated in the resulting coating film.
In Comparative Example 2, Comparative Example 3, Comparative Example 6, and Comparative Example 7 having a low solid content (total concentration of peroxotitanic acid and tetraethoxysilane) and a low tetraethoxysilane concentration, the coating film having a pencil hardness of H or higher Was not obtained. Therefore, the solid content concentration and the titanium oxide concentration ratio were 0.6 mass% / 1.6 mass% = 0.375 (Example 5) to 3.4 mass% / 1.6 mass% = 2.13 (Example). In 14), when the tetraethoxysilane concentration in the solid content concentration is adjusted to 30% by mass or more, a good coating film having a pencil hardness of H or more and excellent surface smoothness can be obtained. In the case of Comparative Example 4, Comparative Example 8, and Comparative Example 9 in which the peroxotitanic acid concentration is 0, the pencil hardness and the adhesion degree are good, and the surface smoothness is inferior compared with other examples. It was. Therefore, when the mass ratio of peroxotitanic acid: tetraethoxysilane is 10:90 to 70:30, a coating film having good pencil hardness and adhesion can be obtained.

Examples 14 to 18 and Reference Example 2
(Method for producing composition for forming titanium oxide photocatalyst coating film)
Tetraethoxysilane is added to an aqueous solution adjusted to pH 3 with nitric acid, and the mixture is stirred for a whole day and night with a stirrer to perform hydrolysis, and then sodium alkanesulfonate (trade name “hydrophilic accelerator” (manufactured by Clariant Japan Co., Ltd.)) Was added to prepare a tetraethoxysilane hydrolyzate aqueous solution. On the other hand, with respect to pure water, the sulfur-containing titanium oxide powder obtained in Reference Example 1 was added at a predetermined ratio and dispersed to prepare a water slurry of the sulfur-containing titanium oxide powder. A peroxotitanic acid aqueous solution and ammonium polyacrylate (trade name “Poise 2100”; (manufactured by Kao Corporation)) are added to the water slurry at a predetermined ratio, and then treated with a ball mill and a bead mill. A mixed aqueous solution of acid, ammonium polyacrylate and a slurry containing titanium oxide powder containing sulfur was prepared. The operation conditions of the ball mill and the bead mill are the same as those in the above embodiment. To this mixed aqueous solution, the tetraethoxysilane hydrolyzate aqueous solution was added and stirred to prepare a sulfur-containing titanium oxide photocatalyst coating composition (coating solution). The coating liquids obtained in Reference Example 2 and Examples 13 to 18 were excellent in dispersibility without agglomeration after standing at room temperature for 24 hours.

The concentration of sulfur-containing titanium oxide powder in the coating solution is 1.3% by mass, the concentration of peroxotitanic acid and tetraethoxysilane is 1.5% by mass (mixing ratio is 3 to 97), and the amount of ammonium polyacrylate added is It prepared so that it might become 0.05 mass%. The concentration of sodium alkanesulfonate in the coating film forming composition was 0% by mass (Reference Example 2), 0.04% by mass (Example 14), 0.08% by mass (Example 15), 0.12% by mass. (Example 16), 0.16 mass% (Example 17), and 0.20 mass% (Example 18).
(Formation and evaluation of titanium oxide photocatalyst coating)
The compositions for forming a titanium oxide photocatalyst coating film of Examples 14 to 18 and Reference Example 2 were prepared by dipping a substrate having a hydrophobic surface and then drying at room temperature for 24 hours to form a titanium oxide photocatalyst coating film. The substrate having a hydrophobic surface was prepared by dipping an acrylic resin plate on an alkoxy oligomer (product name KR400) manufactured by Shin-Etsu Chemical Co., Ltd. whose main component is methyltrimethoxysilane and drying it at room temperature for 24 hours. . Evaluation of the titanium oxide photocatalyst coating film was performed by measuring its hardness and adhesion. The measurement of hardness and adhesion is the same as in the above example. The results are shown in Table 10. Note that the pencil hardness of Reference Example 2 was 3B and the degree of adhesion was 0. On the other hand, the pencil hardness when the slide glass having the hydrophilic surface of the above example was dipped was 6H and the adhesion degree was 10. Table 10 shows the results. As can be seen from Table 10, by adding alkanesulfonic acid, a good coating film can be obtained even on a hydrophobic substrate.

Claims (20)

  Contains sulfur-containing titanium oxide powder, organosilane compound, peroxotitanic acid and dispersion medium, and the amount of the organosilane compound is based on the mass, with respect to the titanium oxide concentration in the titanium oxide photocatalyst coating composition. Titanium oxide photocatalyst coating film characterized in that it is 0.37 to 2.2 times the total concentration with peroxotitanic acid and 30% or more and 99% or less of the total concentration with peroxotitanic acid Forming composition.   The sulfur-containing titanium oxide powder is obtained by hydrolyzing or neutralizing an aqueous titanium chloride solution with an alkali to obtain a solid, and at this stage, sulfur or a sulfur-containing compound is mixed, and then a solid containing sulfur or a sulfur-containing compound is obtained. The composition for forming a titanium oxide photocatalyst coating film according to claim 1, wherein the composition is obtained by firing a product.   The composition for forming a titanium oxide photocatalyst coating film according to claim 1 or 2, wherein the organosilane compound is an organosilane or a hydrolyzate of an organosilane.   The composition for forming a titanium oxide photocatalyst coating film according to claim 3, wherein the organosilane is tetraethoxysilane.   The compounding quantity of the said sulfur containing titanium oxide powder is 0.8-20 mass% in the said composition for titanium oxide photocatalyst coating film formation, The any one of Claims 1-4 characterized by the above-mentioned. Composition for forming a titanium oxide photocatalyst coating film.   Furthermore, the composition for titanium oxide photocatalyst film formation of any one of Claims 1-5 characterized by containing alkanesulfonic acid salt.   It contains a sulfur-containing titanium oxide powder, an organosilane compound, peroxotitanic acid, an alkane sulfonate, and a dispersion medium, and the content of the alkane sulfonate is 0.00 in the composition for forming a titanium oxide photocatalyst coating film. A composition for forming a titanium oxide photocatalyst coating film, which is from 04 to 0.4% by mass.   Furthermore, polyacrylic acid salt is contained, The composition for titanium oxide photocatalyst coating film formation of any one of Claims 1-7 characterized by the above-mentioned.   Furthermore, 1 or more types of sodium phosphate, potassium phosphate, and sodium hexametaphosphate are contained, The composition for titanium oxide photocatalyst coating film formation of any one of Claims 1-8 characterized by the above-mentioned.   A method for producing a composition for forming a titanium oxide photocatalyst coating film, wherein a sulfur-containing titanium oxide powder, an organosilane compound, and peroxotitanic acid are dispersed in a dispersion medium to obtain the composition according to claim 1.   Furthermore, alkanesulfonic acid salt is disperse | distributed to a dispersion medium, The manufacturing method of the composition for titanium oxide photocatalyst coating film formation of Claim 10 characterized by the above-mentioned.   A composition for forming a titanium oxide photocatalyst coating film, wherein a sulfur-containing titanium oxide powder, an organosilane compound, peroxotitanic acid and an alkanesulfonate are dispersed in a dispersion medium to obtain the composition according to claim 7. Manufacturing method.   Furthermore, polyacrylate is disperse | distributed to a dispersion medium, The manufacturing method of the composition for titanium oxide photocatalyst coating film formation of Claim 11 or 12 characterized by the above-mentioned.   An aqueous solution in which organosilane or a hydrolyzate thereof is mixed in a dispersion medium and a slurry in which sulfur-containing titanium oxide powder containing peroxotitanic acid is dispersed are mixed to obtain the composition according to claim 1. A method for producing a composition for forming a titanium oxide photocatalyst coating film.   The composition according to claim 7, wherein an aqueous solution in which organosilane or a hydrolyzate thereof and alkanesulfonate are mixed in a dispersion medium is mixed with a slurry in which a sulfur-containing titanium oxide powder containing peroxotitanic acid is dispersed. A method for producing a composition for forming a titanium oxide photocatalyst coating film.   16. The titanium oxide photocatalyst coating film according to claim 14, wherein the hydrolyzate of organosilane is hydrolyzed by adding organosilane to an aqueous solvent adjusted to pH 1 to 4. A method for producing the composition.   The method for producing a composition for forming a titanium oxide photocatalyst coating film according to claim 14, wherein the aqueous solution obtained by mixing the organosilane or a hydrolyzate thereof with a dispersion medium further contains an alkane sulfonate.   The coating film for photocatalysts obtained by apply | coating the composition for titanium oxide photocatalyst coating film formation of any one of Claims 1-9 to a base material, and drying.   The coated product for photocatalysts obtained by apply | coating the composition for titanium oxide photocatalyst coating-film formation of any one of Claims 1-9 to a base material, and drying.   The photocatalyst coating material obtained by apply | coating the composition for titanium oxide photocatalyst coating-film formation of Claim 6 or 7 to the base material which has a hydrophobic surface, and drying.