Titanium oxide coating liquid

The present invention relates to a titanium oxide coating liquid capable of forming a photocatalytic coating film that exhibits air purification, deodorization, water purification, antibacterial, antifouling effects, etc. by light irradiation.

Since titanium oxide can exert a strong oxidizing action when it absorbs ultraviolet rays, it has been used in various applications as illustrated below in recent years. 1. Air purification by removing environmental pollutants such as nitrogen oxides (NOx) and sulfur oxides (SOx) emitted from automobile exhaust gas, etc. 2. Deodorization by removing malodorous substances such as ammonia, acetaldehyde, hydrogen sulfide, and methyl mercaptan 3. Purified water by decomposing and removing organic chlorine compounds such as tetrachlorethylene and trihalomethane 4, antibacterial by sterilizing and further decomposing the corpse 5. Antifouling to prevent dirt caused by sand and dirt adhering to the oil by decomposing the oil

Titanium oxide may be used in a state of being suspended in a solution (in a state of not being fixed) or in a state of being fixed to a base material. Generally, since the size of the surface area is proportional to the photocatalytic ability, the former can exhibit higher catalytic activity, but from the viewpoint of practicality, the latter is often adopted. When the latter is adopted, a method of fixing titanium oxide to the substrate by using a binder component is common.

It is known that peroxotitanic acid, which is not decomposed by titanium oxide, is used as the binder component (Patent Document 1). By using peroxotitanic acid as a binder component, it is possible to form a photocatalytic coating film capable of exhibiting excellent adhesiveness over a long period of time.

Further, as a method for forming a photocatalytic coating film, a method of applying and drying a dispersion obtained by water-dispersing titanium oxide and a binder component is known (Reference 2).

However, when a dispersion having a low viscosity that can be used in the gravure coating method is prepared using only water as a dispersion medium, there is a problem that the amount of water becomes too large and it takes time to dry. Then, as a method of improving the drying rate, there is a method of reducing the amount of water by using water and alcohol such as ethanol in combination as a dispersion medium. However, when water and alcohol such as ethanol are used in combination, There has been a problem that the stability over time is lowered due to gelation of peroxotitanic acid as a binder component, decomposition and precipitation, and the like. That is, it is a dispersion that has both fluidity and quick-drying properties that can be used in a coating method with a high coating speed such as the gravure coating method, and is stable over time. At present, a dispersion liquid capable of forming a photocatalytic coating film capable of exhibiting adhesiveness has not yet been found.

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 9-262481</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2006-159028</text></patcit></p>

<p> Therefore, an object of the present invention is to apply and dry a titanium oxide coating liquid that is stable over time and has both fluidity and quick-drying properties that can be used in a coating method having a high application speed such as a gravure coating method. It is an object of the present invention to provide a titanium oxide coating liquid capable of forming a photocatalytic coating film capable of exhibiting excellent adhesiveness over a long period of time. Another object of the present invention is to provide a photocatalytic coating film capable of exhibiting excellent adhesiveness over a long period of time obtained by using the titanium oxide coating liquid.</p>

<p> As a result of diligent studies to solve the above problems, the present inventors, when a chelating agent is added to a dispersion containing titanium oxide, peroxotitanic acid as a binder component, water, and alcohol, the peroxotitanic acid Is stabilized by the chelating agent and can maintain high dispersibility, so that it is stable over time and has sufficient fluidity and quick-drying property to be used in a coating method with a high coating speed such as the gravure coating method. It has been found that it is possible to form a dispersion liquid having both of them, and by applying and drying the dispersion liquid, it is possible to form a photocatalytic coating film capable of exhibiting excellent adhesiveness over a long period of time. The present invention has been completed based on these findings.</p><p> That is, the present invention provides a titanium oxide coating solution containing at least the following components. (A) Titanium oxide particles (B) Peroxotitanic acid as a binder component (C) Chelating agent (D) Water (E) Alcohol</p><p> As the (C) chelating agent, a diketone, a diol, a triol, or a tetraol having 3 to 6 carbon atoms is preferable.</p><p> The content of the alcohol (E) is preferably 20 to 55% by weight based on the total amount (100% by weight) of the titanium oxide coating solution.</p><p> The content of the water (D) is preferably 35 to 80% by weight based on the total amount (100% by weight) of the titanium oxide coating liquid.</p><p> The present invention also provides a photocatalytic coating film obtained by applying and drying the titanium oxide coating solution.</p>

<p> Since the titanium oxide coating liquid according to the present invention contains water and ethanol as dispersion media, it can exhibit quick-drying properties while having fluidity compatible with the gravure coating method. Further, even if water and ethanol are contained, the storage stability is excellent, and a stable dispersed state can be maintained without gelation and / or separation. Further, since peroxotitanic acid is used as a binder component, a coating film having high film forming property and having excellent adhesiveness can be quickly formed by coating and drying, and moreover, titanium oxide particles can be formed. Since it is not decomposed by photocatalytic action, it has excellent durability and can fix titanium oxide particles on various adherend surfaces for a long period of time. Further, the photocatalytic coating film obtained by applying and drying the titanium oxide coating solution according to the present invention can decompose harmful chemical substances into water and carbon dioxide by irradiation with light, and has antibacterial and antifungal properties. It can be used for various purposes such as deodorization, air purification, water purification, and antifouling.</p>

<figref num="1">An optical micrograph (a) of the photocatalytic coating film (8) obtained by applying and drying the titanium oxide coating solution (8) obtained in Example 8 and the titanium oxide obtained in Comparative Example (2). It is an optical micrograph (b) of the photocatalytic coating film (10) obtained by applying and drying the coating liquid (10). The scales of photographs (a) and (b) are both 500.00 μm / div.</figref>

[(A) Titanium oxide particles] The titanium oxide particles of the present invention may be any particles having a photocatalytic action, and examples thereof include rutile-type, anatase-type, and brookite-type titanium oxide particles. In the present invention, it is particularly preferable to use rutile-type titanium oxide particles.

The rutyl-type titanium oxide particles contain, for example, a titanium compound in the presence of a hydrophilic polymer (for example, polyvinylpyrrolidone, polyvinyl alcohol, etc.) as a structure control agent, and an aqueous medium (for example, water, or water and a water-soluble organic solvent). It can be synthesized by hydrothermal treatment [for example, 100 to 200 ° C. for 3 to 48 hours (preferably 6 to 12 hours)].

Examples of the titanium compound include a trivalent titanium compound and a tetravalent titanium compound. Examples of the trivalent titanium compound include titanium trihalogenates such as titanium trichloride and titanium tribromide. Among the trivalent titanium compounds in the present invention, titanium trichloride (TiCl) is inexpensive and easily available.₃) Is preferable.

Further, examples of the tetravalent titanium compound in the present invention include a compound represented by the following formula (1). Ti (OR)_tX_4-t (1) (In the formula, R represents a hydrocarbon group, X represents a halogen atom, and t represents an integer from 0 to 3).

Examples of the hydrocarbon group in R include C such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl._1-4Aliphatic hydrocarbon groups and the like can be mentioned.

Examples of the halogen atom in X include chlorine, bromine, iodine and the like.

Examples of such a tetravalent titanium compound include TiCl.₄, TiBr₄, TiI₄Tetra Halogenated Titanium; Ti (OCH)₃) Cl₃, Ti (OC₂H₅) Cl₃, Ti (OC₄H₉) Cl₃, Ti (OC₂H₅) Br₃, Ti (OC₄H₉) Br₃Etc. Trihalogenated Alkoxy Titanium; Ti (OCH)₃)₂Cl₂, Ti (OC₂H₅)₂Cl₂, Ti (OC₄H₉)₂Cl₂, Ti (OC₂H₅)₂Br₂Dihalogenated dialkoxy titanium; Ti (OCH)₃)₃Cl, Ti (OC₂H₅)₃Cl, Ti (OC₄H₉)₃Cl, Ti (OC₂H₅)₃Examples thereof include monohalogenated trialkoxytitanium such as Br. As the tetravalent titanium compound in the present invention, titanium tetrahalogenated is preferable because it is inexpensive and easily available, and titanium tetrachloride (TiCl) is particularly preferable.₄) Is preferable.

In particular, when a tetravalent titanium compound is used as the titanium compound, the reaction temperature is 110 to 220 ° C (preferably 150 ° C to 220 ° C) without adding a hydrophilic polymer as a structure control agent. Rutile-type titanium oxide particles can be synthesized by subjecting them to hydrothermal treatment in an aqueous medium for 2 hours or more (preferably 5 to 15 hours) under a pressure equal to or higher than the saturated vapor pressure at the reaction temperature.

The specific surface area of the titanium oxide particles in the present invention is, for example, 20 to 100 m.²/ g, preferably 40-90m²/ g, especially preferably 50-85m²/ g. When the specific surface area of the titanium oxide particles is less than the above range, the adsorption capacity of the reactants tends to decrease and the photocatalytic ability tends to decrease, while when the specific surface area of the titanium oxide particles exceeds the above range, excited electrons and holes tend to decrease. The separability of the particles is reduced, and the photocatalytic capacity tends to be reduced.

Further, in the present invention, titanium oxide particles carrying transition metal ions (titanium oxide particles carrying transition metal ions) may be used. Titanium oxide particles carrying transition metal ions have responsiveness in a wide wavelength range from the ultraviolet region to the visible light region, and exhibit high catalytic activity even under light sources in normal living spaces such as sunlight, incandescent lamps, and fluorescent lamps. can do.

Further, the transition metal ion is selectively supported on one of the oxidation reaction surface and the reduction reaction surface (particularly, the oxidation reaction surface) of the exposed crystal surface of the titanium oxide particles, that is, the oxidation reaction and the reduction. The reaction field of the reaction can be separated more spatially, thereby increasing the separability of excited electrons and holes, and suppressing the recombination of excited electrons and holes and the progress of the reverse reaction to extremely low levels. It is preferable in that it can exhibit higher photocatalytic activity.

The transition metal ion may be any one that has an absorption spectrum in the visible light region and can inject electrons into the conduction band in the excited state. For example, group 3 to 11 elemental ions in the periodic table, among others. Periodic Table Group 8-11 elemental ions are preferred, especially trivalent iron ions (Fe)³⁺) Is preferable. In supporting iron ions on titanium oxide particles, trivalent iron ions (Fe)³⁺) Is easily adsorbed and is a divalent iron ion (Fe)²⁺) Has a property of being hard to be adsorbed, and thus surface selectivity can be easily imparted by utilizing the property.

The transition metal ions can be supported on the titanium oxide particles by an impregnation method in which the titanium oxide particles are impregnated with the transition metal ions.

Specifically, impregnation can be performed by dispersing titanium oxide particles in an aqueous solution, immersing the particles, and adding transition metal ions while stirring. For example, trivalent iron ions (trivalent iron ions) as transition metal ions ( Fe³⁺) Can be used by adding an iron compound (for example, iron (III) nitrate, iron (III) sulfate, iron (III) chloride, etc.).

The amount of the transition metal ion added is, for example, 0.01 to 3.0% by weight, preferably 0.05 to 1.0% by weight, based on the titanium oxide particles. When the amount of transition metal ions added is less than the above range, the amount of transition metal ions carried on the surface of titanium oxide particles tends to decrease, and the photocatalytic activity tends to decrease, while the amount of transition metal ions added exceeds the above range. Then, the excited electrons do not act effectively due to the reverse electron transfer of the injected electrons, and the photocatalytic activity tends to decrease. The immersion time is, for example, 30 minutes to 24 hours, preferably 1 to 10 hours.

When the titanium oxide particles are impregnated with transition metal ions, it is preferable to irradiate them with excitation light. When irradiated with excitation light, electrons in the valence band of the titanium oxide particles are excited to the conduction band, holes are generated in the valence band, and excited electrons are generated in the conduction band, which diffuse to the particle surface and on each exposed crystal surface. Excited electrons and holes are separated according to the characteristics to form an oxidation reaction surface and a reduction reaction surface. In this state, when a trivalent iron ion is impregnated as a transition metal ion, for example, a trivalent iron ion (Fe) is impregnated.³⁺) Is adsorbed on the oxidation reaction surface, but trivalent iron ions (Fe) on the reduction reaction surface.³⁺) Is a divalent iron ion (Fe)²⁺) And divalent iron ion (Fe)²⁺) Has the property of being difficult to adsorb, so it elutes in the solution, and as a result, iron ions (Fe) only on the oxidation reaction surface.³⁺)-Supported metal ion-supported titanium oxide particles can be obtained.

As the method of irradiating the excitation light, it suffices if it is possible to irradiate light having an energy equal to or higher than the bandgap energy, and for example, it can be performed by irradiating ultraviolet rays. As the ultraviolet irradiation means, for example, an ultraviolet exposure device using a light source that efficiently generates ultraviolet rays such as a medium / high pressure mercury lamp, a UV laser, a UV-LED, and a black light can be used. The irradiation amount of the excitation light is, for example, 0.1 to 300 mW / cm.², Preferred 1 ~ 5mW / cm²Is.

Further, in the present invention, a sacrificial agent may be added at the time of impregnation. By adding a sacrificial agent, transition metal ions can be supported on a specific exposed crystal plane with a higher selectivity on the surface of titanium oxide particles. As the sacrificial agent, it is preferable to use an organic compound that easily emits electrons by itself, for example, alcohols such as methanol and ethanol; carboxylic acids such as acetic acid; ethylenediaminetetraacetic acid (EDTA) and triethanolamine (TEA). Amine and the like can be mentioned.

The amount of the sacrificial agent added can be appropriately adjusted, and is, for example, 0.5 to 5.0 vol%, preferably 1.0 to 2.0 vol% of the titanium oxide solution. The sacrificial agent may be used in excess.

The metal ion-supported titanium oxide particles obtained by the above method can be separated and purified by, for example, separation means such as filtration, concentration, distillation, extraction, crystallization, recrystallization, column chromatography, or a separation means combining these.

[(B) Binder component] The binder component has a function of fixing the titanium oxide particles to the adherend. The present invention is characterized in that peroxotitanic acid is used as a binder component. Peroxotitanic acid can be used alone or in combination with other binder components (eg, silicon compounds, fluororesins, etc.). Peroxotitanic acid has a high film-forming property, and when applied and dried, a coating film having excellent adhesiveness can be quickly formed, and moreover, it is decomposed by the photocatalytic action of titanium oxide particles. Therefore, the durability is excellent, and the titanium oxide particles can be fixed on the surface of the adherend for a long period of time.

Peroxotitanic acid is, for example, TiCl in the presence of basic substances (eg, aqueous ammonia, sodium hydroxide, etc.).₄It can be synthesized by adding a hydrogen peroxide solution to an aqueous solution of a titanium compound such as.

Peroxotitanic acid is considered to be a dinuclear complex represented by the following formula (2). Ti₂O₅(OH)_x^(2-x) (2) (In the formula, x indicates an integer from 1 to 6)

[(C) Chelating agent] The chelating agent is preferably a compound having a site that coordinates with titanium and a site that exhibits hydrophobicity, and the chelating agent was obtained by coordinating with peroxotitanic acid, which is the binder component. The chelated compound preferably has an affinity for both water and alcohol.

As the chelating agent in the present invention, for example, using one or more compounds selected from diketone, diol, triol, and tetraol having 3 to 6 carbon atoms can be used for the composition of other additives, solvents, and the like. It is preferable in that the compatibility can be appropriately adjusted accordingly. These can be used alone or in combination of two or more.

Examples of the diketone having 3 to 6 carbon atoms include acetylacetone and the like.

Examples of the diol having 3 to 6 carbon atoms include dialkanols such as 1,3-propanediol and 1,5-pentanediol; N-substituted or unsubstituted dialkanolamines such as diethanolamine and diisopropanolamine. be able to.

Examples of the triol having 3 to 6 carbon atoms include trialkanols such as glycerol; N-substituted or unsubstituted trialkanolamines such as triethanolamine, triisopropanolamine, and triethanolamine derivatives.

Examples of the tetraol having 3 to 6 carbon atoms include tetraalkanol such as pentaerythritol.

In the present invention, it is preferable to use triol or tetraol having 3 to 6 carbon atoms as the chelating agent, and in particular, N-substituted or unsubstituted trialkanolamine such as triethanolamine, or pentaerythritol. It is preferable to use tetraalkanol such as, etc., in that a titanium oxide coating liquid having even better dispersion stability can be obtained.

[(D) Water] The water is not particularly limited, and for example, distilled water, purified water, industrial purified water, deionized water and the like can be used.

[(E) Alcohol] As the alcohol, it is preferable to use an alcohol having excellent solubility in water and excellent volatility. In the present invention, for example, a monohydric alcohol having 1 to 3 carbon atoms (preferably 1 to 2, particularly preferably 1) such as methanol, ethanol, and isopropanol is preferable. These can be used alone or in combination of two or more.

[Titanium oxide coating liquid] The titanium oxide coating liquid of the present invention contains at least the following components. (A) Titanium oxide particles (B) Peroxotitanic acid as a binder component (C) Chelating agent (D) Water (E) Alcohol

The method for preparing the titanium oxide coating liquid is not particularly limited as long as the above components (A) to (E) can be mixed. For example, the above components (A) to (D) are mixed, and then the above components (A) to (D) are mixed. The method of adding the component (E) or the above-mentioned components (C) and (E) are mixed in advance, and the obtained mixed solution is mixed with the above-mentioned components (A), (B) and (D). Examples thereof include a method of adding.

The blending amount of the component (A) is, for example, 1.0 to 10.0% by weight, preferably 1.0 to 6.0% by weight, and particularly preferably 2.0 to 5.0% by weight of the total amount (100% by weight) of the titanium oxide coating liquid. If the blending amount of the component (A) is less than the above range, it tends to be difficult to sufficiently exert the photocatalytic action. On the other hand, if the blending amount of the component (A) exceeds the above range, the viscosity of the titanium oxide coating liquid tends to be too high, and coating by the gravure coating method tends to be difficult.

The blending amount of the component (B) is, for example, 0.1 to 5.0% by weight, preferably 0.1 to 3.0% by weight, and particularly preferably 0.1 to 1.0% by weight of the total amount (100% by weight) of the titanium oxide coating liquid. When the blending amount of the component (B) is less than the above range, the adhesion retention property of the titanium oxide particles to the adherend and the deterioration prevention property of the adherend tend to decrease. On the other hand, if the blending amount of the component (B) exceeds the above range, the viscosity of the titanium oxide coating liquid tends to be too high, and coating by the gravure coating method tends to be difficult.

The blending amount of the component (C) is, for example, 0.1 to 5.0% by weight, preferably 0.1 to 3.0% by weight, and particularly preferably 0.1 to 1.0% by weight of the total amount (100% by weight) of the titanium oxide coating liquid. If the blending amount of the component (C) is less than the above range, it tends to be difficult to maintain the dispersibility of peroxotitanic acid, and it tends to be difficult to prevent the viscosity of the titanium oxide coating liquid from increasing or separation. There is. On the other hand, if the blending amount of the component (C) exceeds the above range, it tends to be difficult to maintain the dispersibility of peroxotitanic acid.

The blending amount of the component (D) is, for example, 35 to 80% by weight, preferably 40 to 75% by weight, and particularly preferably 45 to 75% by weight of the total amount (100% by weight) of the titanium oxide coating liquid. If the blending amount of the component (D) is less than the above range, the viscosity of the titanium oxide coating liquid becomes too high, and it tends to be difficult to apply by the gravure coating method. On the other hand, if the blending amount of the component (D) exceeds the above range, quick-drying tends to be difficult to obtain.

The blending amount of the component (E) is, for example, 20 to 55% by weight, preferably 20 to 50% by weight, based on the total amount (100% by weight) of the titanium oxide coating liquid. If the blending amount of the component (E) is less than the above range, quick-drying tends to be difficult to obtain. On the other hand, if the blending amount of the component (E) exceeds the above range, the viscosity of the titanium oxide coating liquid tends to be too high, and coating by the gravure coating method tends to be difficult.

The mixing ratio of the component (B) and the component (C) in the titanium oxide coating liquid is, for example, 0.3 to 4.0 parts by weight, preferably 0.5 to 3.5 parts by weight of the component (C) with respect to 1 part by weight of the component (B). Parts by weight, particularly preferably 0.75 to 3.00 parts by weight. When the blending amount of the component (C) exceeds the above range, the adhesion retention of the titanium oxide particles to the adherend tends to decrease, while when the blending amount of the component (C) falls below the above range, the component ( It tends to be difficult to maintain the dispersibility of B), and it tends to be difficult to prevent the viscosity of the titanium oxide coating liquid from increasing and separation.

Furthermore, as the mixing ratio of the component (D) and the component (E) in the titanium oxide coating liquid, the component (E) is, for example, 0.25 to 1.50 parts by weight, preferably 0.25 with respect to 1 part by weight of the component (D). It is ~ 1.25 parts by weight, particularly preferably 0.33 ~ 1.00 parts by weight. If the blending amount of the component (E) exceeds the above range, the storage stability tends to decrease, while if the blending amount of the component (E) falls below the above range, quick-drying tends to be difficult to obtain. ..

In the titanium oxide coating liquid according to the present invention, in addition to the above components (A) to (E), compounds usually blended in the titanium oxide coating liquid for forming a photocatalytic coating film as other components are appropriately added as needed. Can be matched. Examples of other components include a coating aid, a drying rate adjusting agent, a viscosity adjusting agent, a wettability adjusting agent, and the like. The blending amount of the other components may be within a range that does not impair the effects of the present invention, and is, for example, 10% by weight or less (preferably 0.01 to 10% by weight) with respect to the total amount (100% by weight) of the titanium oxide coating liquid. %).

The titanium oxide coating liquid according to the present invention can exhibit quick-drying properties while having sufficient fluidity, and when used in the gravure coating method, for example, has a viscosity of 10 to 80 cP (preferably 20 to 50 cP). ) Is preferable.

[Photocatalytic coating film] The photocatalytic coating film of the present invention is obtained by applying and drying the titanium oxide coating solution, and is produced, for example, through the following steps. Step 1: A step of preparing a titanium oxide coating solution containing at least the above components (A) to (E). Step 2: A step of applying a titanium oxide coating solution to the surface of the adherend and drying it.

The coating amount of the titanium oxide coating liquid is not particularly limited, and for example, the content of titanium oxide particles is 0.5 g / m.²Above (for example, 0.5 ~ 5.0g / m², Preferably 0.5 ~ 3.0g / m²). When the coating amount of the titanium oxide coating liquid is less than the above range, the photocatalytic ability tends to decrease.

The means for applying the titanium oxide coating solution to the adherend is not particularly limited, for example, a gravure coating method, a roll coating method, a spray coating method, or the like. After being applied to the surface of the adherend, a coating film can be formed quickly by drying (evaporating the dispersion medium). As a drying method, it may be dried at room temperature or heated to dry. Since the titanium oxide coating liquid of the present invention can impart fluidity while having quick-drying properties, a photocatalytic coating film can be efficiently produced with excellent accuracy by means such as a gravure coating method, which has a high coating speed. It can be suitably used for the purpose of use.

The titanium oxide coating liquid may be applied directly to the surface of the adherend, for example, and an undercoat layer is provided by applying a coating agent containing a binder component (for example, peroxotitanic acid) to the surface of the adherend in advance. A titanium oxide coating liquid may be applied thereto. When the undercoat layer is provided, the adherend and the photocatalytic coating film are completely separated by the undercoat layer. Therefore, even if a base material made of an organic material is used as the adherend, the photocatalytic action is completely blocked and the photocatalytic action is completely blocked. The body can be protected from damage. When the undercoat layer is provided on the surface of the adherend, the thickness thereof is, for example, 0.1 to 1.0 μm, preferably 0.2 to 0.5 μm.

The adherend of the photocatalyst coating film of the present invention is not particularly limited, and various plastic materials [for example, polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer weight) are not particularly limited. Olefin resin containing α-olefin as monomer component such as coalescence (EVA); polyester resin such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT); polyvinyl chloride (PVC) ); Vinyl acetate resin; Polyphenylene sulfide (PPS); Amid resin such as polyamide (nylon) and total aromatic polyamide (aramid); Polystyrene resin; Polyether ether ketone (PEEK) etc.], Rubber material (for example, Natural rubber, synthetic rubber, silicon rubber, etc.), metal materials (eg, aluminum, copper, iron, stainless steel, etc.), paper materials (eg, paper, paper-like substances, etc.), wood materials (eg, wood, MDF, etc.) Various materials such as boards, plywood, etc.), fiber materials (for example, non-woven fabrics, woven fabrics, etc.), leather materials, inorganic materials (for example, stones, concrete, etc.), glass materials, porcelain materials, etc. can be mentioned.

Since the photocatalytic coating film formed by the above method has titanium oxide particles as a photocatalyst, it can exhibit an extremely high photocatalytic action and can decompose harmful chemical substances into water and carbon dioxide by irradiation with light. Is. Therefore, it can be used for various purposes such as antibacterial and antifungal, deodorizing, air purification, water purification, and antifouling. Furthermore, since it is excellent in adhesiveness and durability to the surface of the adherend, it can exhibit excellent photocatalytic activity for a long period of time.

In addition, especially when transition metal ion-supported titanium oxide particles are used as a photocatalyst, they have responsiveness in a wide wavelength range from the ultraviolet region to the visible light region, and are normal living spaces such as sunlight, incandescent lamps, and fluorescent lamps. Because it can absorb the light in the room and exert high catalytic activity, it shows high gas decomposition performance and antibacterial action even in a low-light environment such as indoors, and it shows indoor wallpaper and furniture, as well as in homes, hospitals, schools, etc. It can be applied to a wide range of applications such as environmental purification in public facilities and high functionality of home appliances.

<p> Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.</p><p> Example 1 40% by weight titanium oxide water slurry liquid (rutile type titanium oxide content: 0.7 g, trade name "STR-100N", manufactured by Sakai Chemical Industry Co., Ltd.) 1.7 g and 1% by weight peroxotitanate aqueous solution (containing peroxotitanic acid) Amount: 0.06 g, trade name "Tio Sky Coat", manufactured by Tio Techno Co., Ltd.) 5.9 g, water 0.4 g was added, and the mixture was stirred until the liquid became uniform. To this, 0.2 g of triethanolamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added as a chelating agent, and after stirring until the solution became uniform, 8.0 g of ethanol was added with stirring to apply titanium oxide coating solution (titanium oxide coating solution). 1) was obtained.</p><p> Examples 2 to 8, Comparative Examples 1 and 2 Titanium oxide coating liquids (2) to (10) were obtained in the same manner as in Example 1 except that the blending amount of each component was changed as described in the table below.</p><p> The titanium oxide coating liquids (1) to (10) obtained in Examples and Comparative Examples were allowed to stand for 1 week under the conditions of 22 ° C and 60% RH, and then the state of the liquid was visually observed, and the following criteria were used. Evaluated according to. &lt;Evaluation criteria&gt; Uniform without separation: Gelling or separation: ×</p><p><tables num="1"><img file="JP2013104035A_D0001.tif" /></tables></p><p> Further, the titanium oxide coating liquid (8) obtained in Example 8 and the titanium oxide coating liquid (10) obtained in Comparative Example (2) were placed on the surface of the PET film as a base material, respectively, with wire bars. Using 1.0g / m²A photocatalytic coating film (8) and a photocatalyst coating film (10) were obtained by applying and drying at 80 ° C. When the obtained photocatalyst coating film was observed using an optical microscope, the photocatalyst coating film (8) was homogeneous, but the photocatalyst coating film (10) was inhomogeneous and the film quality was poor (see Fig. 1). ).</p>