JP5869846B2 - Titanium oxide coating solution - Google Patents

Description

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

Since titanium oxide can exhibit a strong oxidizing action when it absorbs ultraviolet rays, it has been used in various applications as exemplified below.
1. Air purification by removal of environmental pollutants such as nitrogen oxides (NOx) and sulfur oxides (SOx) emitted from automobile exhaust gases, etc. 2. Odorous substances such as ammonia, acetaldehyde, hydrogen sulfide, methyl mercaptan, etc. Deodorization 3 by removal, purified water 4 by decomposing and removing organochlorine compounds such as tetrachloroethylene and trihalomethane, antibacterial 5 by sterilizing and further decomposing the dead body, decomposing the oil, decomposing oil, sand and dirt adhere to the oil Antifouling to prevent dirt generated

  Titanium oxide may be used in a state of being suspended in a solution (in an unfixed state) or in a state of being fixed to a base material. In general, since the surface area is proportional to the photocatalytic activity, the former can exhibit higher catalytic activity, but the latter is often adopted from the viewpoint of practicality. When the latter is employed, a method of fixing titanium oxide to a substrate using a binder component is common.

  As the binder component, it is known to use peroxotitanic acid that is not decomposed by titanium oxide (Patent Document 1). By using peroxotitanic acid as a binder component, it is possible to form a photocatalytic coating film that can exhibit excellent adhesion over a long period of time.

  As a method for forming a photocatalytic coating film, a method of applying and drying a dispersion obtained by dispersing titanium oxide and a binder component in water is known (Cited Document 2).

  However, when a dispersion having a viscosity low enough to 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 is excessive and drying takes time. And as a method for improving the drying speed, there is a method of reducing the amount of water by using a combination of alcohol such as ethanol with water as a dispersion medium, but when using a combination of water and alcohol such as ethanol, There has been a problem that the stability with time decreases due to gelation or decomposition and precipitation of peroxotitanic acid as a binder component. In other words, it has both fluidity and quick-drying properties that can be used for coating methods such as gravure coating methods, and is a stable dispersion over time. The present condition is that the dispersion liquid which can form the photocatalyst coating film which can exhibit adhesiveness has not yet been found.

Japanese Patent Laid-Open No. 9-262481 JP 2006-159028 A

Accordingly, an object of the present invention is a titanium oxide coating solution that is stable over time and has both fluidity and quick drying properties that can be used in a coating method having a high coating speed such as a gravure coating method. It is providing the titanium oxide coating liquid which can form the photocatalyst coating film which can exhibit the adhesiveness outstanding over a long period of time.
Another object of the present invention is to provide a photocatalyst coating film that can exhibit excellent adhesion over a long period of time obtained by using the titanium oxide coating solution.

  As a result of diligent studies to solve the above problems, the present inventors have found that 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 added. Is stabilized by a chelating agent and can maintain high dispersibility, so that it has fluidity and quick-drying that are stable over time and can be used for coating methods such as gravure coating methods. It has been found that a dispersion liquid can be formed and a photocatalyst coating film that can exhibit excellent adhesion over a long period of time can be formed by applying and drying the dispersion liquid. The present invention has been completed based on these findings.

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

  As said (C) chelating agent, C3-C6 diketone, diol, a triol, or a tetraol is preferable.

  The content of the (E) alcohol is preferably 20 to 55% by weight of the total amount of titanium oxide coating solution (100% by weight).

  The content of (D) water is preferably 35 to 80% by weight of the total amount of titanium oxide coating solution (100% by weight).

  The present invention also provides a photocatalytic coating film obtained by applying and drying the titanium oxide coating solution.

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

An optical micrograph (a) of the photocatalyst coating (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 microscope photograph (b) of the photocatalyst coating film (10) obtained by apply | coating and drying a coating liquid (10). The scales of the photos (a) and (b) are both 500.00 μm / div.

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

  The rutile-type titanium oxide particles include, for example, a titanium compound in the presence of a hydrophilic polymer (for example, polyvinylpyrrolidone, polyvinyl alcohol, etc.) as a structure control agent in an aqueous medium (for example, water or water and a water-soluble organic solvent). And a hydrothermal treatment [for example, 100 to 200 ° C., 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 trihalides such as titanium trichloride and titanium tribromide. As the trivalent titanium compound in the present invention, titanium trichloride (TiCl ₃ ) is preferable because it is inexpensive and easily available.

Moreover, the tetravalent titanium compound in this invention can mention the compound etc. which are represented by following formula (1), for example.
Ti (OR) _t X _4-t (1)
(In the formula, R represents a hydrocarbon group, X represents a halogen atom, and t represents an integer of 0 to 3).

Examples of the hydrocarbon group for R include C _1-4 aliphatic hydrocarbon groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl.

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

Examples of such tetravalent titanium compounds include titanium tetrahalides such as TiCl ₄ , TiBr ₄ , and TiI ₄ ; Ti (OCH ₃ ) Cl ₃ , Ti (OC ₂ H ₅ ) Cl ₃ , and Ti (OC _{4). H 9) Cl 3, Ti (} OC 2 H 5) Br 3, Ti (OC 4 H 9) trihalide alkoxy titanium Br _{3 such; Ti (OCH 3) 2 Cl} 2, Ti (OC 2 H 5) 2 Dihalogenated dialkoxytitanium such as Cl ₂ , Ti (OC ₄ H ₉ ) ₂ Cl ₂ , Ti (OC ₂ H ₅ ) ₂ Br ₂ ; Ti (OCH ₃ ) ₃ Cl, Ti (OC ₂ H ₅ ) ₃ Cl, Examples thereof include monohalogenated trialkoxytitanium such as Ti (OC ₄ H ₉ ) ₃ Cl and Ti (OC ₂ H ₅ ) ₃ Br. As the tetravalent titanium compound in the present invention, titanium tetrahalide is preferable, and titanium tetrachloride (TiCl ₄ ) is particularly preferable because it is inexpensive and easily available.

  In particular, when a tetravalent titanium compound is used as the titanium compound, the reaction temperature is 110 to 220 ° C. (preferably 150 to 220 ° C.) without adding a hydrophilic polymer as a structure control agent. Rutile-type titanium oxide particles can be synthesized by 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 in.

As a specific surface area of the titanium oxide particle in this invention, it is 20-100 m < ² > / g, for example, Preferably it is 40-90 m < ² > / g, Most preferably, it is 50-85 m < ² > / g. When the specific surface area of the titanium oxide particles is below the above range, the adsorption capacity of the reactants tends to be reduced and the photocatalytic performance tends to be reduced. On the other hand, when the specific surface area of the titanium oxide particles exceeds the above range, excited electrons and holes There is a tendency that the separability of the photocatalyst decreases and the photocatalytic ability decreases.

  In the present invention, titanium oxide particles supporting transition metal ions (transition metal ion-supporting titanium oxide particles) may be used. Transition metal ion-supported titanium oxide particles have responsiveness over a wide wavelength range from the ultraviolet range to the visible light range, 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 ions are selectively supported on one of the oxidation reaction surface or the reduction reaction surface (particularly the oxidation reaction surface) of the exposed crystal surface of the titanium oxide particles. The reaction field of the reaction can be separated more spatially, thereby increasing the separation of excited electrons and holes, and suppressing the recombination of excited electrons and holes and the progress of reverse reaction to a very low level, It is preferable at the point which can exhibit higher photocatalytic activity.

Any transition metal ion may be used as long as it has an absorption spectrum in the visible light region and can inject electrons into the conduction band in an excited state, such as Group 3 to 11 element ions in the periodic table. Periodic table group 8 to group 11 element ions are preferred, and trivalent iron ions (Fe ³⁺ ) are particularly preferred. When iron ions are supported on titanium oxide particles, trivalent iron ions (Fe ³⁺ ) are easily adsorbed, and divalent iron ions (Fe ²⁺ ) are difficult to adsorb. This is because surface selectivity can be easily imparted.

  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, the impregnation can be performed by dispersing and immersing the titanium oxide particles in an aqueous solution and adding a transition metal ion while stirring. For example, trivalent iron ions ( When Fe ³⁺ is used, it can be carried out by adding an iron compound (for example, iron (III) nitrate, iron (III) sulfate, iron (III) chloride, etc.).

  The addition amount of the transition metal ion is, for example, 0.01 to 3.0% by weight, preferably 0.05 to 1.0% by weight with respect to the titanium oxide particles. When the amount of transition metal ions added is below the above range, the amount of transition metal ions supported on the titanium oxide particle surface 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. As immersion time, it is 30 minutes to 24 hours, for example, Preferably it is 1 to 10 hours.

When impregnating the titanium oxide particles with transition metal ions, it is preferable to irradiate excitation light. When irradiated with excitation light, the electrons in the valence band of the titanium oxide particles are excited in the conduction band, holes are generated in the valence band, and excited electrons are generated in the conduction band, which are diffused to the particle 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, for example, when trivalent iron ions are impregnated as transition metal ions, trivalent iron ions (Fe ³⁺ ) are adsorbed on the oxidation reaction surface, but trivalent iron ions ( Fe ³⁺ ) is reduced to divalent iron ions (Fe ²⁺ ), and divalent iron ions (Fe ²⁺ ) are difficult to adsorb, so they elute into the solution, resulting in an oxidation reaction surface. Only metal ion-carrying titanium oxide particles carrying iron ions (Fe ³⁺ ) can be obtained.

As a method for irradiating the excitation light, it is only necessary to irradiate light having energy equal to or higher than the band gap energy. As the ultraviolet irradiation means, for example, an ultraviolet exposure apparatus 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 , preferably 1 to 5 mW / cm ² .

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

  The addition amount of the sacrificial agent can be adjusted as appropriate, and is, for example, 0.5 to 5.0 vol%, preferably 1.0 to 2.0 vol% of the titanium oxide solution. An excessive amount of the sacrificial agent may be used.

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

[(B) Binder component]
The binder component has a function of fixing the titanium oxide particles to the adherend. In the present invention, peroxotitanic acid is used as a binder component. Peroxotitanic acid can be used alone or in combination with other binder components (for example, silicon compounds, fluorine resins, etc.). Peroxotitanic acid has a high film-forming property, and can be quickly formed into a coating film having excellent adhesiveness by coating and drying, and it can also be decomposed by the photocatalytic action of titanium oxide particles. Therefore, the titanium oxide particles can be fixed to the adherend surface over a long period of time.

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

Peroxotitanic acid is considered to be a binuclear complex represented by the following formula (2).
Ti ₂ O ₅ (OH) _x ^(2-x) (2)
(Wherein x represents an integer of 1 to 6)

[(C) chelating agent]
The chelating agent is preferably a compound having a site coordinated to titanium and a site exhibiting hydrophobicity, and the chelating agent was obtained by coordinating with peroxotitanic acid as the binder component. The chelate compound preferably has affinity for both water and alcohol.

  As the chelating agent in the present invention, for example, it is possible to use one or more compounds selected from diketones having 3 to 6 carbon atoms, diols, triols, and tetraols in the composition of other additives and solvents. Accordingly, the compatibility can be suitably adjusted. These can be used alone or in combination of two or more.

  As said C3-C6 diketone, acetylacetone etc. can be mentioned, for example.

  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 trialkanol such as glycerol; N-substituted or unsubstituted trialkanolamine such as triethanolamine, triisopropanolamine, and triethanolamine derivatives.

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

  In the present invention, it is particularly preferable to use a triol or tetraol having 3 to 6 carbon atoms as a chelating agent, in particular, an N-substituted or unsubstituted trialkanolamine such as triethanolamine, or pentaerythritol. It is preferable to use a tetraalkanol such as a titanium oxide coating solution having further excellent dispersion stability.

[(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, monohydric alcohols having 1 to 3 carbon atoms (preferably 1 to 2, particularly preferably 1) such as methanol, ethanol and isopropanol are preferable. These can be used alone or in combination of two or more.

[Titanium oxide coating solution]
The titanium oxide coating solution 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 solution is not particularly limited as long as the components (A) to (E) can be mixed. For example, the components (A) to (D) are mixed, and then In the method of adding the component (E), the above components (C) and (E) are mixed in advance, and the resulting mixture is mixed with the above components (A), (B) and (D). The method of adding etc. is mentioned.

  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, particularly preferably 2% of the total amount of titanium oxide coating solution (100% by weight). 0.0 to 5.0% by weight. When the amount of component (A) is less than the above range, it tends to be difficult to sufficiently exhibit the photocatalytic action. On the other hand, if the amount of component (A) exceeds the above range, the viscosity of the titanium oxide coating solution 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, particularly preferably 0, of the total amount of titanium oxide coating solution (100% by weight). 0.1 to 1.0% by weight. When the blending amount of the component (B) is less than the above range, the adhesion retention of the titanium oxide particles to the adherend and the deterioration preventing property of the adherend tend to be lowered. On the other hand, if the amount of component (B) exceeds the above range, the viscosity of the titanium oxide coating solution tends to be too high, and coating by the gravure coating method tends to be difficult.

  The compounding amount of the component (C) is, for example, 0.1 to 5.0% by weight, preferably 0.1 to 3.0% by weight, particularly preferably 0, based on the total amount (100% by weight) of the titanium oxide coating solution. 0.1 to 1.0% by weight. When the amount of component (C) is less than the above range, it tends to be difficult to maintain the dispersibility of peroxotitanic acid, and it is difficult to prevent an increase in the viscosity or separation of the titanium oxide coating solution. There is. On the other hand, when the amount of component (C) exceeds the above range, it tends to be difficult to maintain the dispersibility of peroxotitanic acid.

  As a compounding quantity of the said component (D), it is 35-80 weight% of a titanium oxide coating liquid whole quantity (100 weight%), Preferably it is 40-75 weight%, Most preferably, it is 45-75 weight%. If the amount of component (D) is less than the above range, the viscosity of the titanium oxide coating solution tends to be too high, and coating by the gravure coating method tends to be difficult. On the other hand, when the amount of component (D) exceeds the above range, quick drying tends to be difficult to obtain.

  As a compounding quantity of the said component (E), it is 20 to 55 weight% of the titanium oxide coating liquid whole quantity (100 weight%), Preferably it is 20 to 50 weight%. When the amount of component (E) is less than the above range, quick drying tends to be difficult to obtain. On the other hand, when the compounding amount of the component (E) exceeds the above range, the viscosity of the titanium oxide coating solution tends to be too high and application by the gravure coating method tends to be difficult.

  As a mixing ratio of the component (B) and the component (C) in the titanium oxide coating solution, the component (C) is, for example, 0.3 to 4.0 parts by weight, preferably 1 part by weight of the component (B), preferably 0.5 to 3.5 parts by weight, particularly preferably 0.75 to 3.00 parts by weight. When the compounding amount of the component (C) exceeds the above range, the adhesion retention of the titanium oxide particles to the adherend tends to decrease. On the other hand, when the compounding amount of the component (C) is below the above range, the component (C There is a tendency that it is difficult to maintain the dispersibility of B), and it is difficult to prevent an increase in the viscosity of the titanium oxide coating solution, separation, and the like.

  Furthermore, as a blending ratio of the component (D) and the component (E) in the titanium oxide coating solution, the component (E) is, for example, 0.25 to 1.50 parts by weight with respect to 1 part by weight of the component (D). The amount is preferably 0.25 to 1.25 parts by weight, particularly preferably 0.33 to 1.00 parts by weight. When the compounding amount of the component (E) exceeds the above range, the storage stability tends to be lowered. On the other hand, when the compounding amount of the component (E) is below the above range, quick drying tends to be difficult to obtain. .

  In addition to the above components (A) to (E), the titanium oxide coating solution according to the present invention is appropriately blended with other compounds that are usually blended in a titanium oxide coating solution for forming a photocatalyst coating film as necessary. can do. Examples of other components include a coating aid, a drying speed adjusting agent, a viscosity adjusting agent, and a wettability adjusting agent. 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).

  The titanium oxide coating solution according to the present invention can exhibit quick drying properties while having sufficient fluidity. When used in a gravure coating method, for example, the viscosity is 10 to 80 cP (preferably 20 to 50 cP). ) Is preferably adjusted.

[Photocatalytic coating]
The photocatalyst 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 adherend surface and drying it.

The coating amount of the titanium oxide coating solution is not particularly limited. For example, the titanium oxide particle content is 0.5 g / m ² or more (for example, 0.5 to 5.0 g / m ² , preferably 0.5 to 3.0 g / m ² ). When the coating amount of the titanium oxide coating solution 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, or a spray coating method. After coating on the surface of the adherend, a coating film can be quickly formed by drying (evaporating the dispersion medium). As a drying method, it may be dried at room temperature or may be dried by heating. Since the titanium oxide coating solution of the present invention can provide fluidity while having quick drying properties, a photocatalytic coating film can be efficiently produced with excellent accuracy by means of a high coating speed such as a gravure coating method. It can use suitably for the use to do.

  The titanium oxide coating solution 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) in advance on the surface of the adherend. A titanium oxide coating solution may be applied thereon. When an undercoat layer is provided, the adherend and the photocatalyst coating film are completely separated from each other by the undercoat layer. Therefore, even when a substrate made of an organic material is used as the adherend, the photocatalytic action is completely blocked, The kimono can be protected from damage. When an undercoat layer is provided on the adherend surface, 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) Olefin-based resins containing α-olefin such as coalescence (EVA) as monomer component; Polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT); Polyvinyl chloride (PVC) ); Vinyl acetate resin; polyphenylene sulfide (PPS); amide resin such as polyamide (nylon), wholly aromatic polyamide (aramid); polyimide resin; polyether ether ketone (PEEK) etc.], rubber material (for example, Natural rubber, synthetic rubber, silicon rubber, etc.), Genus materials (eg, aluminum, copper, iron, stainless steel, etc.), paper materials (eg, paper, paper-like substances, etc.), wood materials (eg, wood, wood boards such as MDF, plywood, etc.), fiber materials (eg, Non-woven fabric, woven fabric, etc.), leather materials, inorganic materials (for example, stone, concrete, etc.), glass materials, porcelain materials, and the like.

  The photocatalytic coating film formed by the above method has titanium oxide particles as a photocatalyst, so it can exhibit extremely high photocatalytic action, and can decompose harmful chemical substances into water and carbon dioxide by light irradiation. It is. Therefore, it can be used for various applications such as antibacterial fungi, deodorization, air purification, water purification, and antifouling. Furthermore, since it is excellent in adhesion and durability to the adherend surface, it can exhibit excellent photocatalytic activity over a long period of time.

  In particular, when using transition metal ion-supported titanium oxide particles as a photocatalyst, it has responsiveness over a wide wavelength range from the ultraviolet region to the visible light region, and is used in ordinary living spaces such as sunlight, incandescent lamps, and fluorescent lamps. Because it absorbs light and exhibits high catalytic activity, it exhibits high gas decomposition performance and antibacterial action even in low-light environments such as indoors, such as indoor wallpaper and furniture, home, hospital, school, etc. It can be applied to a wide range of applications such as environmental purification in public facilities and higher functionality of home appliances.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited by these Examples.

Example 1
40% by weight titanium oxide aqueous slurry (rutile-type titanium oxide content: 0.7 g, trade name “STR-100N”, manufactured by Sakai Chemical Industry Co., Ltd.) and 1% by weight peroxotitanic acid aqueous solution (peroxotitanium) Acid content: 0.06 g, trade name “Tio Sky Coat” (manufactured by Tio Techno Co., Ltd.) 5.9 g, and water 0.4 g were added and stirred until the liquid became uniform.
Here, 0.2 g of triethanolamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added as a chelating agent, and after stirring until the liquid became uniform, 8.0 g of ethanol was added with stirring, and titanium oxide coating was applied. A liquid (1) was obtained.

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 amount of each component was changed as described in the following table.

About the titanium oxide coating liquids (1) to (10) obtained in the examples and comparative examples, after standing for 1 week under the conditions of 22 ° C. and 60% RH, the state of the liquids was visually observed and in accordance with the following criteria. evaluated.
<Evaluation criteria>
Uniform without separation: ○
Gelation or separation: ×

Moreover, about the titanium oxide coating liquid (8) obtained in Example 8, and the titanium oxide coating liquid (10) obtained in Comparative Example (2), respectively, on the surface of the PET film as a substrate, a wire bar Was applied at 1.0 g / m ² and dried at 80 ° C. to obtain a photocatalyst coating film (8) and a photocatalyst coating film (10).
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 heterogeneous and the film quality was poor (see FIG. 1). ).

Claims (5)

A titanium oxide coating solution containing at least the following components.
(A) Rutile-type titanium oxide particles (B) Peroxotitanic acid as a binder component (C) At least one compound (D) selected from the group consisting of diketones, triols, and tetraols having 3 to 6 carbon atoms Water (E) Monohydric alcohol (C) The content of at least one compound selected from the group consisting of diketone, triol, and tetraol having 3 to 6 carbon atoms is 0.3 to 4.0 relative to 1 part by weight of (B). The titanium oxide coating solution according to claim 1, which is part by weight . (E) The titanium oxide coating solution according to claim 1 or 2, wherein the content of the monovalent alcohol is 20 to 55% by weight of the total amount (100% by weight) of the titanium oxide coating solution.   (D) Content of water is 35-80 weight% of titanium oxide coating liquid whole quantity (100 weight%), The titanium oxide coating liquid in any one of Claims 1-3.   The photocatalyst coating film obtained by apply | coating and drying the titanium oxide coating liquid as described in any one of Claims 1-4.