WO2012011367A1

WO2012011367A1 - Photocatalyst coating liquid and product having photocatalytic function

Info

Publication number: WO2012011367A1
Application number: PCT/JP2011/064679
Authority: WO
Inventors: 仁高見; 酒谷　能彰
Original assignee: 住友化学株式会社
Priority date: 2010-07-23
Filing date: 2011-06-27
Publication date: 2012-01-26
Also published as: JP2012025849A

Abstract

Provided are: a photocatalyst coating liquid capable of obtaining a photocatalyst layer which has excellent adhesion to the substrate when forming the photocatalyst layer on a surface of a substrate, the photocatalyst layer exhibiting high photocatalytic activity through the irradiation of a practical light source such as fluorescent light; and a product having a photocatalytic function provided with a photocatalyst layer on the surface. The photocatalyst coating liquid comprises, in a predetermined ratio, (1) photocatalyst particles, (2) niobium oxide sol particles, (3) colloidal silica particles, (4) silicon alkoxides, and (5) a solvent, and the solid content obtained by volatilizing volatile components from the photocatalyst coating liquid is in a predetermined ratio relative to the photocatalyst coating liquid.

Description

Photocatalyst body coating liquid and photocatalyst functional product

The present invention relates to a photocatalyst coating liquid and a photocatalytic functional product.

When a semiconductor is irradiated with light having energy higher than the band gap, electrons in the valence band are excited to the conduction band and holes are generated in the valence band. The holes generated in this way have a strong oxidizing power, and the excited electrons have a strong reducing power, so that they exert a redox action on a substance in contact with the semiconductor. This redox action generates active oxygen species such as OH radicals, and can decompose organic substances and the like. A semiconductor capable of exhibiting such an action is called a photocatalyst, and titanium oxide and tungsten oxide are known as the photocatalyst. Among these, tungsten oxide is a photocatalyst that exhibits high photocatalytic action under illumination of a fluorescent lamp.

In Patent Document 1, an adhesive layer is provided on a substrate, a binder component made of a metal oxide gel or a metal hydroxide gel is mixed with a photocatalyst coating liquid containing a photocatalyst, and the photocatalyst coating liquid is applied to the adhesive layer. It is disclosed that a photocatalyst-supporting structure in which photocatalyst particles are less likely to fall off when applied on top is obtained.

International Publication No. 97/000134

However, in the photocatalyst carrying structure as described above, the adhesive strength between the adhesive layer and the base material or the adhesive strength between the photocatalyst body layer and the adhesive layer is not always sufficient, and the photocatalyst body is easily peeled off from the base material, and a high photocatalyst. No activity was expressed.

Thus, the problem of the present invention is that when a photocatalyst layer is formed on the surface of the substrate, a photocatalyst layer having excellent adhesion to the substrate is obtained, and the photocatalyst layer is irradiated with a practical light source such as a fluorescent lamp. Thus, a photocatalyst coating liquid exhibiting high photocatalytic activity and a photocatalytic functional product having a photocatalyst layer on the surface are provided.

As a result of intensive studies to solve the above problems, the present inventors have completed the present invention shown below.

That is, this invention consists of the following structures.
(I) (1) photocatalyst particles, (2) niobium oxide sol particles, (3) colloidal silica particles, (4) silicon alkoxide, and (5) a photocatalyst coating liquid comprising (2) The oxide equivalent content is 0 to 200 parts by mass with respect to 100 parts by mass of the oxide equivalent of (4), and the oxide equivalent content of (3) is the oxidation of (4). 0 to 280 parts by mass with respect to 100 parts by mass in terms of product, and the total of oxides in terms of (2) and (3) is 100 parts by mass in terms of oxide in (4) 0 to 480 parts by mass with respect to parts, and the total of the oxide equivalents of (2), (3) and (4) is 20 to 500 parts by mass with respect to (1) 100 parts by mass. Yes, solid solution obtained by volatilizing volatile components from the photocatalyst coating liquid A photocatalyst for forming a photocatalyst layer having photocatalytic activity, characterized in that the content in terms of oxide is 0.5 to 30 parts by mass with respect to 100 parts by mass of the photocatalyst coating liquid Provide body coating fluid.
(II) The photocatalyst coating liquid according to (I), wherein the photocatalyst layer exhibits photocatalytic activity when irradiated with at least visible light.
(III) The photocatalyst coating liquid according to (I) or (II), wherein the photocatalyst particles are tungsten oxide particles.
(IV) The photocatalyst coating liquid according to any one of (I) to (III), wherein the photocatalyst particles carry a noble metal.

The present invention is also a photocatalytic functional product comprising a photocatalyst layer on a substrate surface, wherein the photocatalyst layer is formed using the photocatalyst coating liquid according to any one of (I) to (IV). Provided is a photocatalytic functional product.

According to the photocatalyst coating liquid of the present invention, since it contains niobium oxide, colloidal silica, and silicon alkoxide as binders in an optimum composition, it can be adhered even if directly applied to a substrate without providing an adhesive layer on the substrate. It is possible to form a photocatalyst layer that exhibits excellent strength and exhibits sufficient photocatalytic activity. Furthermore, the photocatalyst layer can also provide a photocatalytic functional product that exhibits excellent surface hardness and excellent hydrophilicity and maintains the original excellent photocatalytic action.

The photocatalyst coating liquid of the present invention contains photocatalyst particles, niobium oxide sol particles, colloidal silica particles, silicon alkoxide and a solvent in a predetermined ratio, and the solid content of the photocatalyst coating liquid is set to a predetermined ratio.

[Photocatalyst particles]
The photocatalyst particles in the present invention are oxides having a photocatalytic action, and examples thereof include titanium oxide particles and tungsten oxide particles. In particular, tungsten oxide particles are irradiated with visible light (wavelength of about 400 nm to about 800 nm). Since it exhibits high photocatalytic activity, it is suitable for the present invention.

[Titanium oxide particles]
Titanium oxide particles are particulate titanium oxides that exhibit particularly high photocatalytic activity when irradiated with ultraviolet light.
Examples of the titanium oxide particles include metatitanic acid particles, titanium dioxide [TiO ₂ ] particles whose crystal types are anatase type, brookite type, rutile type, and the like.

Metatitanic acid particles can be obtained, for example, by the following method (A).
Method (A): Method of hydrolysis by heating an aqueous solution of titanyl sulfate

The titanium dioxide particles can be obtained, for example, by any one of the following methods (B-1) to (B-3).
Method (B-1): A method of obtaining a precipitate by adding a base to an aqueous solution of titanyl sulfate or titanium chloride without heating, and firing the obtained precipitate. Method (B-2): Titanium alkoxide Method of (B-3): Method of calcining metatitanic acid by adding water, aqueous solution of acid or base solution to obtain precipitate, and calcining the resulting precipitate

The titanium dioxide particles obtained by the above methods (B-1) to (B-3) can be obtained as anatase type, brookite type or rutile type crystal types depending on the baking temperature and baking time at the time of baking.

In addition to the above-described method, titanium oxide can be obtained by, for example, the sulfuric acid method and the chlorine method described in “Titanium oxide” (Gaku Kiyono, published by Gihodo Publishing), JP-A-2001-72419, No. 2001-190953, JP-A No. 2001-316116, JP-A No. 2001-322816, JP-A No. 2002-29749, JP-A No. 2002-97019, WO 01/10552, JP-A No. 2001. No. -21457, JP 2002-239395 A, WO 03/080244, WO 02/053501, JP 2007-69093 A, Chemistry Letters, Vol.32, No.2, P.196. -197 (2003), Chemistry Letters, Vol.32, No.4, P.364-365 (2003), Chemistry Letters, Vol.32, No.8, P.772-773 (2003), Chem. Mater. , 17, P.1548-1552 (2005), JP 2001 278625, JP-A-2001-278626, JP-A-2001-278627, JP-A-2001-30241, JP-A-2001-335321, JP-A-2001-354422, JP-A-2002-29750 Examples thereof include methods described in JP-A No. 2002-47012, JP-A No. 2002-60221, JP-A No. 2002-193618, JP-A No. 2002-249319, and the like.

The titanium oxide obtained by the above method may be used alone or in combination of two or more.

The average dispersed particle size is used as the particle size of the titanium oxide particles. From the viewpoint of effectively exhibiting photocatalytic action, the average dispersed particle size is usually 20 nm to 150 nm, preferably 40 nm to 100 nm.

The BET specific surface area of the titanium oxide particles is usually 100 m ² / g to 500 m ² / g, preferably 300 m ² / g to 400 m ² / g, from the viewpoint of effectively exhibiting photocatalytic action.

[Tungsten oxide particles]
The tungsten oxide particles are particulate tungsten oxides that exhibit high photocatalytic action even when irradiated with visible light (wavelength of about 400 nm to about 800 nm).
The tungsten oxide particles usually include tungsten trioxide [WO ₃ ] particles.
The tungsten trioxide particles can be obtained, for example, by adding an acid to an aqueous solution of tungstate to obtain tungstic acid as a precipitate, and firing the obtained tungstic acid. Moreover, it can also obtain by the method of thermally decomposing by heating ammonium metatungstate and ammonium paratungstate.

The average dispersed particle size is used as the particle size of the tungsten oxide particles. From the viewpoint of effectively exhibiting photocatalytic action, the average dispersed particle size is usually 50 nm to 200 nm, preferably 80 nm to 130 nm.

The BET specific surface area of the tungsten oxide particles is usually 5 m ² / g to 100 m ² / g, preferably 20 m ² / g to 50 m ² / g, from the viewpoint of effectively exhibiting photocatalytic action.

[Niobium oxide sol particles]
The average particle diameter of the niobium oxide sol particles in the present invention is usually 50 nm or less, preferably 30 nm or less, and may be crystalline or amorphous.
Further, in order to improve the dispersion stability of the niobium oxide sol particles, a material in which the surface of the niobium oxide sol particles is appropriately modified with a dispersant may be used. Examples of such niobium oxide sol particles include niobium oxide sol “Nb-X-10” manufactured by Taki Chemical Co., Ltd.

The oxide equivalent content of the niobium oxide sol particles is 0 to 200 parts by mass, preferably 20 to 140 parts by mass, and more preferably 30 to 80 parts by mass with respect to 100 parts by mass of the oxide equivalent of the silicon alkoxide. It is. When the content of the niobium oxide sol particles in terms of oxide exceeds 200 parts by mass, the adhesion between the resulting photocatalyst layer and the substrate is lowered, and the photocatalyst layer is too soft and may cause a problem. Further, when the oxide equivalent content of the niobium oxide sol particles exceeds 140 parts by mass, the photocatalyst layer is easily damaged, and when the oxide equivalent content of the niobium oxide sol particles is less than 20 parts by mass, the photocatalyst is obtained. The hydrophilicity of the body layer is significantly reduced. Further, when the oxide equivalent content of the niobium oxide sol particles exceeds 80 parts by mass, the hydrophilicity corresponding to the hardness of the photocatalyst layer cannot be obtained, and the oxide equivalent content of the niobium oxide sol particles is 30 masses. If it is less than the part, the hydrophilicity of the photocatalyst layer is lowered. The oxide equivalent content of niobium oxide sol particles means the content of Nb ₂ O ₅ when all the niobium components in the niobium oxide sol are converted to Nb ₂ O ₅ , and the oxide equivalent of silicon alkoxide, all the silicon component in the silicon alkoxide means the content of SiO ₂ in the case of conversion into SiO _2, and so on.

[Colloidal silica particles]
The average particle size of the colloidal silica particles in the present invention is usually 50 nm or less, preferably 30 nm or less. For example, colloidal silica manufactured by Nissan Chemical Industries, Ltd., “ST-OXS”, “ST-OS”, “ST -O "can be used.

The oxide equivalent content of the colloidal silica particles is 0 to 280 parts by mass, preferably 160 to 260 parts by mass, more preferably 170 to 230 parts by mass with respect to 100 parts by mass of the oxide equivalent of the silicon alkoxide. It is. When the content of the colloidal silica particles in terms of oxide exceeds 280 parts by mass, the adhesion between the resulting photocatalyst layer and the substrate is lowered, and the photocatalyst layer is too soft and may cause problems. Further, when the oxide equivalent content of the colloidal silica particles exceeds 260 parts by mass, the adhesion of the photocatalyst layer is lowered, and when the oxide equivalent content of the colloidal silica particles is less than 160 parts by mass, The hydrophilicity of the photocatalyst layer is significantly reduced. Further, when the oxide equivalent content of the colloidal silica particles exceeds 230 parts by mass, the photocatalyst layer tends to be damaged, and when the oxide equivalent content of the colloidal silica particles is less than 170 parts by mass, The hydrophilicity of the body layer is reduced.
Note that the oxide equivalent of the colloidal silica particles, all silicon component in the colloidal silica means a content of SiO ₂ in the case of conversion into SiO _2, and so on.

Further, the total oxide content of the niobium oxide sol particles and colloidal silica particles in the photocatalyst coating liquid of the present invention is 0 to 480 parts by mass with respect to 100 parts by mass of the oxide equivalent of silicon alkoxide, The amount is preferably 200 to 330 parts by mass, more preferably 210 to 310 parts by mass. If the total oxide content of the niobium oxide sol particles and colloidal silica particles exceeds 480 parts by mass, the adhesion between the resulting photocatalyst layer and the substrate will be lowered, and the photocatalyst layer will be too soft. May occur. In addition, when the total oxide content of niobium oxide sol particles and colloidal silica particles exceeds 330 parts by mass, the hydrophilicity of the photocatalyst layer is remarkably reduced, and the oxide conversion of niobium oxide sol particles and colloidal silica particles is also reduced. If the sum total of content is less than 200 mass parts, the adhesiveness of a photocatalyst body layer will fall, and also a photocatalyst body layer will become easy to be damaged. Further, when the total oxide content of niobium oxide sol particles and colloidal silica particles exceeds 310 parts by mass, the hydrophilicity of the photocatalyst layer is lowered, and the oxide conversion of niobium oxide sol particles and colloidal silica particles is reduced. When the total content is less than 210 parts by mass, the photocatalyst layer is easily damaged.

Furthermore, the total of the oxide equivalent content of niobium oxide sol particles, colloidal silica particles, and silicon alkoxide in the photocatalyst coating liquid of the present invention is 100 parts by mass of the photocatalyst particle content in the photocatalyst coating liquid of the present invention. On the other hand, it is usually 20 to 500 parts by mass, but the photocatalyst layer obtained from the photocatalyst coating liquid may be 100 to 450 parts by mass for the purpose of obtaining good adhesion to the substrate. When the total content of niobium oxide sol particles, colloidal silica particles, and silicon alkoxide in terms of oxides is less than 20 parts by mass, the adhesion between the photocatalyst layer and the substrate decreases, while 500 parts by mass is reduced. If it exceeds, the photocatalyst particles are buried in a binder component such as niobium oxide sol particles, making it difficult to obtain a photocatalyst layer having sufficient photocatalytic activity.

[Silicon alkoxide]
Examples of the silicon alkoxide include tetraethoxysilane (ethyl silicate), tetramethoxysilane (methyl silicate), methyltriethoxysilane, methyltriethoxysilane, and hydrolyzates and polymers such as silicon alkoxide. .

〔solvent〕
As the solvent, an aqueous medium containing water as a main component, specifically, a solvent containing 50% by mass or more of water is used, water may be used alone, or a mixed solvent of water and a water-soluble organic solvent. May be used.
Examples of the water-soluble organic solvent include water-soluble alcohol solvents such as methanol, ethanol, propanol, and butanol, acetone, methyl ethyl ketone, methyl cellosolve, and ethyl cellosolve.

In the photocatalyst coating liquid of the present invention, the content in terms of solid oxide obtained by volatilizing a volatile component such as a solvent from the photocatalyst coating liquid is usually 0. 5 to 30 parts by weight (that is, 0.5 to 30% by weight with respect to the total amount of the photocatalyst coating liquid), preferably 1 to 20 parts by weight (1 to 20% by weight), more preferably Is used by diluting with water or other solvent so as to be about 2 to 10 parts by mass (2 to 10% by mass). When the solid content is less than 0.5 parts by mass, it becomes difficult to form a photocatalyst layer having a sufficient thickness, and when the solid content exceeds 30 parts by mass, the transparency of the resulting photocatalyst layer is impaired. It will be easier. Moreover, when solid content exceeds 20 mass parts, the layer thickness of a photocatalyst body layer will become thick too much, and the malfunction that a photocatalyst body layer cracks may arise. On the other hand, when the solid content is less than 1 part by mass, it is necessary to perform overcoating or the like to obtain a photocatalyst layer having a required thickness, which increases the cost. Moreover, when solid content exceeds 10 mass parts, when apply | coating to a transparent base material, the transparency of a base material may be impaired. Moreover, when solid content is less than 2 mass parts, the drying process after application | coating takes time and the performance corresponding to cost cannot be obtained.

(Adjustment of photocatalyst coating liquid)
The mixing order and mixing method of the photocatalyst particles, niobium oxide sol particles, colloidal silica particles, silicon alkoxide and solvent when preparing the photocatalyst coating liquid of the present invention are not particularly limited. For example, (a) colloidal silica particles , A method of mixing niobium oxide sol particles with a binder liquid in which silicon alkoxide and a solvent are mixed, and further mixing a photocatalyst dispersion liquid in which the photocatalyst particles are dispersed in a solvent alone, (b) the photocatalyst particles are a solvent alone Examples include a method in which niobium oxide sol particles, colloidal silica particles, and silicon alkoxide are sequentially added to the photocatalyst dispersion dispersed in and mixed, and may be performed with stirring or heating as necessary. May be. Furthermore, when preparing the photocatalyst dispersion liquid, it is possible to add a component constituting the binder in addition to the niobium oxide sol particles, colloidal silica particles, and silicon alkoxide.

[Photocatalyst dispersion]
The hydrogen ion concentration of the photocatalyst dispersion in which the photocatalyst particles are dispersed alone in a solvent is usually pH 2.0 to pH 7.0, preferably pH 3.0 to pH 6.0. When the hydrogen ion concentration is less than pH 2.0, the acidity is too strong and the handling is troublesome. When the pH exceeds 7.0, when the photocatalyst particles are tungsten oxide particles, the tungsten oxide particles may be dissolved. The hydrogen ion concentration of the photocatalyst dispersion liquid can be usually adjusted by adding an acid. Examples of the acid that can be used include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, and succinic acid.

[Production of photocatalyst dispersion]
The photocatalyst dispersion liquid can be obtained by adding a photocatalyst particle to a solvent in the presence of a suitable dispersant as necessary and subjecting it to a dispersion treatment. The dispersion treatment can be performed, for example, by an ordinary method using a medium stirring type disperser.
The addition of the photocatalyst particles to the solvent may be performed, for example, by adding the photocatalyst particles directly to the solvent and mixing them. Usually, however, the photocatalyst particles are dispersed in the dispersion medium in advance in the solvent. It is carried out by a method of mixing, and is preferably carried out by a method of further dispersing the photocatalyst particles previously dispersed in a dispersion medium and then mixing them with a solvent.
Examples of the dispersion medium include the solvents described above.

[Production of precious metal-supported photocatalyst dispersion]
The photocatalyst particles in the present invention preferably have a noble metal supported on the surface in order to improve the photocatalytic activity.
As a method for supporting the noble metal on the surface of the photocatalyst particles, for example, a method in which a sacrificial agent is dissolved in the above-described photocatalyst dispersion liquid and light irradiation is performed on the photocatalyst particle dispersion, or And a method of irradiating with light in an aqueous solution in which is dissolved.

[Precursor of precious metal]
As the noble metal precursor, one that can be dissolved in a solvent is used. When such a precursor is dissolved, the noble metal element constituting the precursor usually becomes a noble metal ion having a positive charge and exists in the solvent. The noble metal ions are reduced to zero-valent noble metal by the photocatalytic action of the photocatalyst particles by light irradiation, and are supported on the surfaces of the photocatalyst particles.
Examples of the noble metal include Cu, Pt, Au, Pd, Ag, Ru, Ir, and Rh. Examples of the precursor include hydroxides, nitrates, sulfates, halides, organic acid salts, carbonates, and phosphates of these noble metals. Among these, for the purpose of obtaining high photocatalytic activity, the noble metal is preferably Cu, Pt, Au, or Pd.

Examples of the Cu precursor include copper nitrate (Cu (NO ₃ ) ₂ ), copper sulfate (CuSO ₄ ), copper chloride (CuCl ₂ , CuCl), copper bromide (CuBr ₂ , CuBr), copper iodide ( CuI), copper iodate (CuI ₂ O ₆ ), ammonium copper chloride (Cu (NH ₄ ) ₂ Cl ₄ ), copper oxychloride (Cu ₂ Cl (OH) ₃ ), copper acetate (CH ₃ COOCu, (CH ₃ COO) ₂ Cu), copper formate ((HCOO) ₂ Cu), copper carbonate (CuCO ₃ ), copper oxalate (CuC ₂ O ₄ ), copper citrate (Cu ₂ C ₆ H ₄ O ₇ ), copper phosphate ( CuPO ₄ ) and the like.

Examples of the precursor of Pt include platinum chloride (PtCl ₂ , PtCl ₄ ), platinum bromide (PtBr ₂ , PtBr ₄ ), platinum iodide (PtI ₂ , PtI ₄ ), and platinum potassium chloride (K ₂ (PtCl _4). )), Hexachloroplatinic acid (H ₂ PtCl ₆ ), platinum sulfite (H ₃ Pt (SO ₃ ) ₂ OH), tetraammineplatinum chloride (Pt (NH ₃ ) ₄ Cl ₂ ), tetraammineplatinum hydrogen carbonate (C ₂ H ₁₄₎ N ₄ O ₆ Pt), tetraammine platinum hydrogen phosphate (Pt (NH ₃ ) ₄ HPO ₄ ), tetraammine platinum hydroxide (Pt (NH ₃ ) ₄ (OH) ₂ ), tetraammine platinum nitrate (Pt (NO ₃ ) ₂ (NH ₃ ) ₄ ), tetraammineplatinum tetrachloroplatinum ((Pt (NH ₃ ) ₄ ) (PtCl ₄ )), dinitrodiamine platinum (Pt (NO ₂ ) ₂ (NH ₃ ) ₂ ) And the like.

Examples of the Au precursor include gold chloride (AuCl), gold bromide (AuBr), gold iodide (AuI), gold hydroxide (Au (OH) ₂ ), tetrachloroauric acid (HAuCl ₄ ), tetra Examples thereof include potassium chloroaurate (KAuCl ₄ ) and potassium tetrabromoaurate (KAuBr ₄ ).

Examples of the precursor of Pd include palladium acetate ((CH ₃ COO) ₂ Pd), palladium chloride (PdCl ₂ ), palladium bromide (PdBr ₂ ), palladium iodide (PdI ₂ ), palladium hydroxide (Pd ( OH) ₂ ), palladium nitrate (Pd (NO ₃ ) ₂ ), palladium sulfate (PdSO ₄ ), potassium tetrachloropalladate (K ₂ (PdCl ₄ )), potassium tetrabromopalladate (K ₂ (PdBr ₄ )) , Tetraammine palladium chloride (Pd (NH ₃ ) ₄ Cl ₂ ), tetraammine palladium bromide (Pd (NH ₃ ) ₄ Br ₂ ), tetraammine palladium nitrate (Pd (NH ₃ ) ₄ (NO ₃ ) ₂ ), tetraammine palladium tetra chloropalladate acid _{_{((Pd (NH 3) 4}} ) (PdCl 4)), Te Etc. La chloro palladium ammonium _{_{_{((NH 4) 2 PdCl 4}}} ) and the like.

Precious metal precursors may be used alone or in combination of two or more. The amount used is usually 0.01 parts by mass or more, in terms of cost, in terms of sufficiently improving the photocatalytic action with respect to 100 parts by mass of the photocatalyst particles in terms of precious metal atoms. Is usually 1 part by mass or less, preferably 0.05 to 0.6 parts by mass.

[Sacrificial agent]
When a noble metal is supported on the surface of the photocatalyst particles, a sacrificial agent is used, for example, added to the photocatalyst dispersion.
Examples of the sacrificial agent include alcohols such as ethanol, methanol, and propanol, ketones such as acetone, and carboxylic acids such as oxalic acid.
The sacrificial agent is added after the photocatalyst dispersion liquid is irradiated with light for a certain period of time, and further irradiated with light. The amount of the sacrificial agent is usually 0.001 to 0.3 times by mass, preferably 0.005 to 0.1 times by mass, with respect to the solvent in the photocatalyst dispersion. If the amount of the sacrificial agent used is less than 0.001 times by mass, the noble metal is insufficiently supported on the photocatalyst particles, and if it exceeds 0.3 times by mass, the amount of sacrificial agent is excessive and an effect commensurate with the cost cannot be obtained. .

[Light irradiation]
The photocatalyst dispersion liquid may be irradiated with light while stirring the photocatalyst dispersion liquid. Irradiation may be performed from inside or outside the tube while passing through a transparent glass or plastic tube, or this may be repeated.
The light source is not particularly limited as long as it can irradiate light having energy higher than the band gap of the photocatalyst particles. Specific examples include a germicidal lamp, a mercury lamp, a light emitting diode, a fluorescent lamp, a halogen lamp, a xenon lamp, and a solar light. Light or the like can be used.
The wavelength of the irradiated light is usually 180 nm to 500 nm.
The time for performing the light irradiation is such that a sufficient amount of noble metal can be supported on the photocatalyst particles, so that it is usually 20 minutes or longer, preferably 1 hour or longer, usually 24 hours or shorter, preferably 6 hours or shorter before and after the addition of the sacrificial agent. is there. When the time exceeds 24 hours, most of the precursors of the noble metal have become noble metals and are supported on the photocatalyst particles, and an effect commensurate with the cost of light irradiation cannot be obtained. Moreover, when light irradiation is not performed before the addition of the sacrificial agent, noble metal is not uniformly supported on the photocatalyst particles, and high photocatalytic activity cannot be obtained.

[PH adjustment]
Light irradiation is performed while maintaining the pH of the photocatalyst dispersion liquid at 2.5 to 5.5, preferably 3.0 to 5.0. Usually, when noble metal is supported on the surface of the photocatalyst particles by light irradiation, the pH of the photocatalyst dispersion liquid gradually changes to acidic. Therefore, in order to maintain the pH within the above range, a base is usually added. Good. As a result, a noble metal-supported photocatalyst dispersion having excellent dispersibility, in which the noble metal is supported on the surface of the photocatalyst particles, is obtained.
Examples of the base include aqueous solutions of ammonia, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, lanthanum hydroxide, etc. Among them, ammonia water and water Sodium oxide is preferably used.

[Noble metal-supported photocatalyst particles]
Irradiate light while adjusting the pH, and after adding the sacrificial agent, further irradiate light, whereby the noble metal precursor becomes a noble metal and is supported on the surface of the photocatalyst particle to obtain the desired noble metal-supported photocatalyst particle. . The noble metal-supported photocatalyst particles are dispersed in the solvent used without settling.

〔Additive〕
The photocatalyst coating liquid prepared as described above may contain an additive as long as the dispersibility of the photocatalyst particles and / or noble metal-supported photocatalyst particles is not impaired.

Examples of the additive include those added for the purpose of improving the photocatalytic action, specifically, silicon compounds such as water glass, aluminum compounds such as amorphous alumina, alumina sol, and aluminum hydroxide, zeolites Alkaline earth metal oxides such as kaolinite, magnesium oxide, calcium oxide, strontium oxide, barium oxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, etc. or alkaline earth metal water Examples thereof include oxides, calcium phosphates, molecular sieves, activated carbon, polycondensates of organic polysiloxane compounds, phosphates, fluorine-based polymers, silicon-based polymers, acrylic resins, polyester resins, melamine resins, urethane resins, and alkyd resins. These additives are used alone or in combination of two or more.

[Photocatalytic functional products]
The photocatalyst functional product of the present invention has a photocatalyst layer formed on the surface using the photocatalyst coating liquid obtained as described above.
The photocatalyst layer is formed, for example, by applying a photocatalyst coating liquid onto the surface of a substrate (product) by spin coating, dip coating, doctor blade, spraying or brushing, and then room temperature to 150 ° C., preferably room temperature to 90 ° It can be formed by a conventionally known film forming method such as drying and evaporating the solvent in the temperature range of ° C. and volatilizing the volatile component.
The film thickness of the photocatalyst body layer is not particularly limited, and it is usually set appropriately from several hundred nm to several mm according to its use. The photocatalyst layer may be formed on any part as long as it is an inner surface or an outer surface of the base material (product). For example, the photocatalyst layer is a surface irradiated with light (visible light), and a malodorous substance. It is preferably formed on a surface that is continuously or intermittently connected to a place where the occurrence of a pathogen or a pathogen is present.
The material of the base material (product) is not particularly limited as long as the formed photocatalyst layer can be held at a strength that can be practically used. For example, plastic, metal, ceramics, wood, concrete, paper, etc. Products made of any material can be targeted. In addition, in order to suppress the deterioration of the adhesion between the photocatalyst layer and the substrate due to the photocatalytic action, a known barrier layer made of, for example, a silica component can be formed between the photocatalyst layer and the substrate.

As the plastic, in the case of a thermosetting resin, for example, aramid resin, polyimide resin, epoxy resin, unsaturated polyester resin, phenol resin, urea resin, polyurethane resin, melamine resin, benzoguanamine resin, silicone resin, melamine urea resin In the case of a thermoplastic resin, examples thereof include a condensation polymerization resin and a resin obtained by polymerizing a vinyl monomer.

Examples of the condensation polymerization resin include polyester resins such as polyethylene terephthalate, polyethylene naphthalate, polylactic acid, biodegradable polyester, and polyester liquid crystal polymer; ethylenediamine-adipic acid polycondensate (nylon-66), nylon-6 And polyamide resins such as nylon-12 and polyamide liquid crystal polymers; polyether resins such as polycarbonate resins, polyphenylene oxide, polymethylene oxide, and acetal resins; polysaccharide resins such as cellulose and derivatives thereof;

Examples of resins obtained by polymerizing vinyl monomers include polyolefin resins; polystyrene, poly-α-methylstyrene, styrene-ethylene-propylene copolymers (polystyrene-poly (ethylene / propylene) block copolymers), Styrene-ethylene-butene copolymer (polystyrene-poly (ethylene / butene) block copolymer), styrene-ethylene-propylene-styrene copolymer (polystyrene-poly (ethylene / propylene) -polystyrene block copolymer), Unsaturated aromatic-containing resins such as ethylene-styrene copolymers; polyvinyl alcohol resins such as polyvinyl alcohol and polyvinyl butyral; polymethyl methacrylate, methacrylic acid ester, acrylic acid ester, methacrylic acid amide as monomers Acrylic resins containing acrylic amides; Chlorine resins such as polyvinyl chloride and polyvinylidene chloride; polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetra And fluororesin such as fluoroethylene-hexafluoropropylene copolymer and polyvinylidene fluoride.

The photocatalytic functional product of the present invention has a high photocatalytic effect by light irradiation not only outdoors but also in an indoor environment that receives only light from a visible light source such as a fluorescent lamp, an incandescent bulb, a light emitting diode, and a sodium lamp. Show. Therefore, the photocatalyst coating liquid of the present invention is, for example, a building material such as a ceiling material, tile, glass, wallpaper, wall material, floor, automobile interior material (automobile instrument panel, automobile seat, automobile ceiling material), Light applied by indoor lighting when applied to the surface of base materials that are in contact with an unspecified number of people, such as household appliances such as refrigerators and air conditioners, textile products such as clothes and curtains, train straps, elevator buttons, etc. Irradiation reduces the concentration of volatile organic substances such as formaldehyde and acetaldehyde, aldehydes, mercaptans, ammonia and other malodorous substances, nitrogen oxides, and Staphylococcus aureus, Escherichia coli, anthrax, tuberculosis, cholera, diphtheria , Kill, decompose, and remove pathogens such as tetanus, plague, shigella, botulinum, and legionella Bets can be can be further harmless allergens such as mite allergen and cedar pollen allergen.
In addition, the photocatalytic functional product of the present invention is not only capable of exhibiting sufficient hydrophilicity and exhibiting antifogging properties when irradiated with visible light, but also can be easily wiped off by simply applying water to the dirt. In addition, charging can be prevented.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited by these Examples.
The measurement method in each example is shown below.

1. BET Specific Surface Area The BET specific surface area of the platinum-supported tungsten oxide particles was measured by a nitrogen adsorption method using a specific surface area measuring device [“Monosorb” manufactured by Yuasa Ionics Co., Ltd.].

2. Average dispersed particle size (nm)
Measure the particle size distribution of the sample using a sub-micron particle size distribution analyzer (“N4Plus” manufactured by Coulter, Inc.), and automatically disperse the result of monodisperse mode analysis using the software provided with this device. The diameter.

3. Hardness test The hardness of the photocatalyst layer was measured by a pencil hardness test method (JIS 5600-5-4).

4). Adhesiveness Adhesiveness of the photocatalyst layer to the base material is determined when the adhesive cellophane tape ("CT405AP-24" manufactured by Nichiban Co., Ltd.) is applied to the surface of the photocatalyst layer and then quickly peeled off. It evaluated by whether it peeled simultaneously.

5. Limit contact angle measurement [test specimen preparation (photocatalyst layer formation)]
The obtained photocatalyst coating liquid was applied on a glass plate having a length of 50 mm, a width of 50 mm, and a thickness of 2 mm using a spin coater (trade name “1H-D7”, manufactured by Mikasa Co., Ltd.) at a rotation speed of 1000 rpm. After drying at room temperature, this glass plate was dried at 70 ° C. for 60 minutes to form a photocatalyst layer on one side of the glass plate to prepare a test piece.

[Hydrophilicity evaluation test conditions for hydrophobic organic substances]
From the top of the photocatalyst layer of the test piece, ultraviolet rays were irradiated for 2 days at room temperature in the atmosphere using a commercially available black light as a light source. At this time, the UV intensity in the vicinity of the photocatalyst layer is about ² mW / cm ² (measured by attaching the UV receiver “UD-36” to Topcon UV intensity meter “UVR-2”). did.
Next, n-heptane having an oleic acid concentration of 0.5% by volume was applied to the test piece with a dip coater (“DT-0303-S1” manufactured by SDI), and then dried at 70 ° C. for 15 minutes.
The lifting speed of the dip coater was 10 mm / second, and the immersion time was 10 seconds. Thereafter, the test piece coated with oleic acid was included in the fluorescent lamp from the top of the photocatalyst layer through an acrylic resin plate (“N169” manufactured by Nitto Resin Co., Ltd.) using a commercially available white fluorescent lamp as a light source. The measurement was performed so that the visible light was irradiated, and the contact angle θ of the water droplet after a predetermined time elapsed was measured using a contact angle meter (“CA-A type” manufactured by Kyowa Interface Science Co., Ltd.). The measurement of the contact angle θ of the water droplet was performed 5 seconds after the water droplet (about 0.4 μL) was placed on the photocatalyst layer of the test piece in each case. In this case, the irradiation with visible light was such that the illuminance in the vicinity of the photocatalyst layer was 6000 lux (measured with an illuminometer “T-10” manufactured by Minolta). After irradiation with a fluorescent lamp, oleic acid is decomposed by the photocatalytic action of the photocatalyst body layer, and the contact angle of the water droplet decreases. The angle at which the decrease in the contact angle reaches saturation is defined as the critical contact angle. It can be said that the smaller the limit contact angle, the higher the photocatalytic activity of the photocatalyst layer, that is, the photoinduced hydrophilicity and the organic substance decomposing performance.

6). Volatile organic matter decomposition activity (measurement of acetaldehyde resolution)
The photocatalytic activity was evaluated by measuring a first-order reaction rate constant in the decomposition reaction of acetaldehyde under irradiation of light from a fluorescent lamp. That is, in a glass petri dish (outer diameter 70 mm, inner diameter 66 mm, height 14 mm, capacity about 48 mL), the obtained photocatalyst coating liquid has a dripping amount in terms of solid content per unit area of the bottom surface of 1 g / m ^2. It was dripped so that it was uniformly formed on the entire bottom of the petri dish. Next, the petri dish was dried by holding it in the air at 110 ° C. for 1 hour in the air to form a photocatalyst layer on the bottom of the glass petri dish. The photocatalyst layer is irradiated with UV light from a black light so that the UV intensity is ² mW / cm ² (measured by attaching a UV receiver “UD-36” to Topcon's UV intensity meter “UVR-2”). This was irradiated for 16 hours and used as a photocatalytic activity measurement sample.

Next, the sample for photocatalytic activity measurement is placed in a gas bag (internal volume 1 L) together with the petri dish, and then the inside of the gas bag is evacuated, and then the volume ratio of oxygen to nitrogen is 1: 4. Was mixed with 0.6 L of a mixed gas, and 3 mL of nitrogen gas containing 1% acetaldehyde was sealed therein, and the mixture was kept in the dark at room temperature for 1 hour. Thereafter, using a commercially available white fluorescent lamp as a light source, the illuminance in the vicinity of the measurement sample is 1000 lux through the acrylic resin plate (“N169” manufactured by Nitto Resin Co., Ltd.) (illuminance meter “T-10 manufactured by Minolta Co., Ltd.). ) Was irradiated with visible light from the outside of the gas bag to cause acetaldehyde decomposition reaction. The gas in the gas bag was sampled every 1.5 hours after the light irradiation of the fluorescent lamp was started, and the concentration of acetaldehyde was measured with a gas chromatograph (“GC-14A” manufactured by Shimadzu Corporation). Then, a first-order rate constant was calculated from the concentration of acetaldehyde with respect to the irradiation time, and this was evaluated as acetaldehyde resolution. It can be said that the higher the first-order rate constant, the higher the resolution of acetaldehyde, that is, the photocatalytic activity.

Example 1
[Preparation of precious metal-supported photocatalyst dispersion]
As a solvent, 1 kg of tungsten oxide particles (manufactured by Nippon Inorganic Chemical Industry Co., Ltd.) was added to 4 kg of ion-exchanged water and mixed to obtain a mixture. This mixture was dispersed using a wet medium stirring mill to obtain a tungsten oxide particle dispersion.

To this tungsten oxide particle dispersion, an aqueous solution of hexachloroplatinic acid (H ₂ PtCl ₆ ) is added so that hexachloroplatinic acid is 0.12 parts by mass with respect to 100 parts by mass of tungsten oxide particles in terms of platinum atoms, A hexachloroplatinic acid-containing tungsten oxide particle dispersion was obtained as a raw material dispersion. The solid content (amount of tungsten oxide particles) contained in 100 parts by mass of this dispersion was 17.6 parts by mass (solid content concentration 17.6% by mass). Thereafter, the pH of this dispersion was 2.0.

Next, a pH electrode, a pH controller (set to pH = 3.5) connected to the pH electrode and having a control mechanism for adjusting the pH to a constant level by supplying 0.1 mass% ammonia water, A light irradiation device comprising a glass tube (inner diameter: 37 mm, height: 360 mm) equipped with a pot and equipped with an underwater sterilization lamp (“GLD15MQ” manufactured by Sankyo Electric Co., Ltd.) While dispersing 1200 g of the raw material dispersion adjusted to a solid content concentration of 12.0% by mass at a rate of 1 L / min, the pH of the dispersion was adjusted to 3.5. Light irradiation (ultraviolet irradiation) is performed for 2 hours while circulating the raw material dispersion, and methanol is further added so that the concentration thereof is 1% by mass of the total solvent, and light irradiation is performed for 3 hours while circulating the raw material dispersion. Thus, a platinum-supported tungsten oxide particle dispersion containing coarse particles was obtained. During light irradiation, the pH was constant at 3.5. Thereafter, coarse particles were separated by a centrifugal separator, and further, cation and anion contained in the platinum-supported tungsten oxide particle dispersion were removed by dialysis, and the pH was 3.8 and the average dispersed particle size was A 101 nm platinum-supported tungsten oxide particle dispersion was obtained.

An aqueous ethanol solution was added to the obtained platinum-supported tungsten oxide particle dispersion to obtain a platinum-supported photocatalyst dispersion. The content of the platinum-supported tungsten oxide particles with respect to 100 parts by mass of the platinum-supported photocatalyst dispersion liquid was 5 parts by mass, and the content of ethanol was 30 parts by mass.

When this platinum-supported photocatalyst dispersion was stored at 20 ° C. for 24 hours, no solid-liquid separation was observed after storage. Moreover, when a part of platinum carrying | support tungsten oxide particle dispersion was vacuum-dried and solid content was obtained, the BET specific surface area of the obtained solid content was 45 m < ² > / g.

[Preparation of photocatalyst coating liquid]
210 g of ethanol and 335 g of water were added to 40 g of high purity ethyl silicate (manufactured by Tama Chemical Co., Ltd.). Thereafter, 117.5 g of colloidal silica particles (“ST-OS” manufactured by Nissan Chemical Industries, Ltd., solid content concentration of 20% by mass in terms of oxide) was added to obtain a binder.

Niobium oxide sol particles ("Nb-X-10" manufactured by Taki Chemical Industry Co., Ltd., solid content concentration of 10% by mass in terms of oxide) were diluted with an aqueous ethanol solution to obtain an ethanol-containing niobium oxide sol. The contents of ethanol and niobium oxide sol particles in terms of oxide with respect to 100 parts by mass of the ethanol-containing niobium oxide sol were 30 parts by mass and 5 parts by mass, respectively.

Next, 100 g of ethanol-containing niobium oxide sol was added to 700 g of binder, and 200 g of a platinum-supported photocatalyst dispersion (solid content concentration 5 mass%) was further added to obtain a photocatalyst coating liquid. All of these were performed at room temperature and in the atmosphere, and each component was added with stirring.

The total solid content concentration in terms of oxide in the obtained photocatalyst coating liquid was 5 parts by mass (5% by mass) with respect to 100 parts by mass of the photocatalyst coating liquid. Further, the total solid content of 100 parts by mass includes platinum-supported tungsten oxide particles, niobium oxide sol particles, colloidal silica particles, and ethyl silicate oxide conversions of 20 parts by mass, 10 parts by mass, 47 parts by mass, and 23, respectively. Part by mass was included.

The niobium oxide sol particles, colloidal silica particles, and the total content thereof were 43 parts by mass, 204 parts by mass, and 248 parts by mass, respectively, in terms of oxide with respect to 100 parts by mass of oxide silicate in ethyl silicate. It was. The total content of niobium oxide sol particles, colloidal silica particles, and ethyl silicate in terms of oxide was 400 parts by mass in terms of oxide with respect to 100 parts by mass of platinum-supported tungsten oxide particles.

[Formation of photocatalyst layer]
After applying the photocatalyst coating liquid obtained above to a fully degreased glass plate having a length of 50 mm, a width of 50 mm, and a thickness of 2 mm, a spin coater (trade name “1H-D7”, manufactured by Mikasa Co., Ltd.) is used. The glass plate was applied at a rotation speed of 1000 rpm and dried at room temperature, and then the glass plate was dried at 70 ° C. for 60 minutes to form a photocatalyst layer on one side of the glass plate. When the pencil hardness of the photocatalyst layer was examined, it was 5-6H. Further, when the adhesion of the photocatalyst layer was examined using an adhesive cellophane tape, no peeling of the photocatalyst layer was observed, and the adhesion was good.

When a photocatalyst layer was obtained in the same manner as described above and a hydrophilicity evaluation test was performed using this photocatalyst layer when a hydrophobic organic substance was adhered, the limit contact angle was 5 degrees.

(Example 2)
The content of platinum-supported tungsten oxide particles, niobium oxide sol particles, colloidal silica particles, and ethyl silicate in 100 parts by mass of the total solid content in terms of oxide in the photocatalyst coating liquid is 20 parts by mass and 10 parts by mass, respectively. A photocatalyst coating liquid was prepared in the same manner as in Example 1 except that the content was 45 parts by mass and 25 parts by mass. Moreover, the total solid content concentration in terms of oxide in the obtained photocatalyst coating liquid was 5 parts by mass with respect to 100 parts by mass of the photocatalyst coating liquid.

Niobium oxide sol particles, colloidal silica particles, and the total content thereof were 40 parts by mass, 180 parts by mass, and 220 parts by mass, respectively, in terms of oxides with respect to 100 parts by mass of ethyl silicate in terms of oxides. It was. The total content of niobium oxide sol particles, colloidal silica particles, and ethyl silicate in terms of oxide was 400 parts by mass in terms of oxide with respect to 100 parts by mass of platinum-supported tungsten oxide particles.

Using the photocatalyst coating liquid obtained above, a photocatalyst layer was prepared in the same manner as in Example 1, and the pencil hardness was measured to be 5-6H. Further, when the adhesion of the photocatalyst layer was examined using an adhesive cellophane tape, no peeling of the photocatalyst layer was observed, and the adhesion was good. Further, when the limit contact angle was measured in the same manner as in Example 1, it was 4 degrees.

(Example 3)
The content of platinum-supported tungsten oxide particles, niobium oxide sol particles, colloidal silica particles, and ethyl silicate in 100 parts by mass of the total solid content in terms of oxide in the photocatalyst coating liquid is 20 parts by mass and 10 parts by mass, respectively. A photocatalyst coating liquid was prepared in the same manner as in Example 1 except that the content was 50 parts by mass and 20 parts by mass. Moreover, the total solid content concentration in terms of oxide in the obtained photocatalyst coating liquid was 5 parts by mass with respect to 100 parts by mass of the photocatalyst coating liquid.

The niobium oxide sol particles, colloidal silica particles, and the total content thereof were 50 parts by mass, 250 parts by mass, and 300 parts by mass, respectively, in terms of oxide with respect to 100 parts by mass of ethyl silicate in terms of oxide. It was. The total content of niobium oxide sol particles, colloidal silica particles, and ethyl silicate in terms of oxide was 400 parts by mass in terms of oxide with respect to 100 parts by mass of platinum-supported tungsten oxide particles.

Using the photocatalyst coating liquid obtained above, a photocatalyst layer was prepared in the same manner as in Example 1, and the pencil hardness was measured to be 3-4H. Moreover, when the adhesiveness of the photocatalyst layer was examined using an adhesive cellophane tape, no peeling of the photocatalyst layer was observed, and the adhesiveness was good. Further, when the limit contact angle was measured in the same manner as in Example 1, it was 4 degrees.

Example 4
The content of platinum-supported tungsten oxide particles, niobium oxide sol particles, colloidal silica particles, and ethyl silicate in 100 parts by mass of the total solid content in terms of oxide in the photocatalyst coating liquid is 20 parts by mass and 20 parts by mass, respectively. A photocatalyst coating liquid was prepared in the same manner as in Example 1 except that the content was 40 parts by mass and 20 parts by mass. Moreover, the total solid content concentration in terms of oxide in the obtained photocatalyst coating liquid was 5 parts by mass with respect to 100 parts by mass of the photocatalyst coating liquid.

The niobium oxide sol particles, colloidal silica particles, and the total content thereof were 100 parts by mass, 200 parts by mass, and 300 parts by mass, respectively, in terms of oxides with respect to 100 parts by mass of ethyl silicate in terms of oxides. It was. The total content of niobium oxide sol particles, colloidal silica particles, and ethyl silicate in terms of oxide was 400 parts by mass in terms of oxide with respect to 100 parts by mass of platinum-supported tungsten oxide particles.

Using the photocatalyst coating liquid obtained above, a photocatalyst layer was prepared in the same manner as in Example 1, and the pencil hardness was measured to be 5-6H. Further, when the adhesion of the photocatalyst layer was examined using an adhesive cellophane tape, no peeling of the photocatalyst layer was observed, and the adhesion was good. Further, when the limit contact angle was measured in the same manner as in Example 1, it was 6 degrees.

(Example 5)
The content of platinum-supported tungsten oxide particles, niobium oxide sol particles, colloidal silica particles, and ethyl silicate in 100 parts by mass of the total solid content in terms of oxide in the photocatalyst coating liquid is 20 parts by mass and 30 parts by mass, respectively. A photocatalyst coating liquid was prepared in the same manner as in Example 1 except that the content was 33 parts by mass and 17 parts by mass. Moreover, the total solid content concentration in terms of oxide in the obtained photocatalyst coating liquid was 5 parts by mass with respect to 100 parts by mass of the photocatalyst coating liquid.

The niobium oxide sol particles, colloidal silica particles, and the total content thereof were 176 parts by mass, 194 parts by mass, and 371 parts by mass, respectively, in terms of oxide with respect to 100 parts by mass of ethyl silicate in terms of oxide. It was. The total content of niobium oxide sol particles, colloidal silica particles, and ethyl silicate in terms of oxide was 400 parts by mass in terms of oxide with respect to 100 parts by mass of platinum-supported tungsten oxide particles.

Using the photocatalyst coating liquid obtained above, a photocatalyst layer was prepared in the same manner as in Example 1, and the pencil hardness was measured to be 3-4H. Moreover, when the adhesiveness of the photocatalyst layer was examined using an adhesive cellophane tape, no peeling of the photocatalyst layer was observed, and the adhesiveness was good. Further, when the limit contact angle was measured in the same manner as in Example 1, it was 12 degrees.

(Comparative Example 1)
The content of platinum-supported tungsten oxide particles, niobium oxide sol particles, colloidal silica particles, and ethyl silicate in 100 parts by mass of the total solid content in terms of oxide in the photocatalyst coating liquid is 20 parts by mass and 40 parts by mass, respectively. A photocatalyst coating liquid was prepared in the same manner as in Example 1 except that the content was 27 parts by mass and 13 parts by mass. Moreover, the total solid content concentration in terms of oxide in the obtained photocatalyst coating liquid was 5 parts by mass with respect to 100 parts by mass of the photocatalyst coating liquid.

The niobium oxide sol particles, colloidal silica particles, and the total content thereof were 308 parts by mass, 208 parts by mass, and 515 parts by mass, respectively, in terms of oxide with respect to 100 parts by mass of ethyl silicate in terms of oxide. It was. The total content of niobium oxide sol particles, colloidal silica particles, and ethyl silicate in terms of oxide was 400 parts by mass in terms of oxide with respect to 100 parts by mass of platinum-supported tungsten oxide particles.

Using the photocatalyst coating liquid obtained above, a photocatalyst layer was prepared in the same manner as in Example 1, and when pencil hardness was measured, scratches were generated just by rubbing with an eraser, and the pencil hardness was less than 6B. .

(Comparative Example 2)
The content of platinum-supported tungsten oxide particles, niobium oxide sol particles, colloidal silica particles, and ethyl silicate in 100 parts by mass of the total solid content in terms of oxide in the photocatalyst coating liquid is 20 parts by mass and 50 parts by mass, respectively. A photocatalyst coating liquid was prepared in the same manner as in Example 1 except that the content was 20 parts by mass and 10 parts by mass. Moreover, the total solid content concentration in terms of oxide in the obtained photocatalyst coating liquid was 5 parts by mass with respect to 100 parts by mass of the photocatalyst coating liquid.

The niobium oxide sol particles, colloidal silica particles, and the total content thereof were 500 parts by mass, 200 parts by mass, and 700 parts by mass, respectively, in terms of oxides with respect to 100 parts by mass of ethyl silicate in terms of oxides. It was. The total content of niobium oxide sol particles, colloidal silica particles, and ethyl silicate in terms of oxide was 400 parts by mass in terms of oxide with respect to 100 parts by mass of platinum-supported tungsten oxide particles.

(Comparative Example 3)
The content of platinum-supported tungsten oxide particles, niobium oxide sol particles, colloidal silica particles, and ethyl silicate in 100 parts by mass of the total solid content in terms of oxide in the photocatalyst coating liquid is 20 parts by mass and 10 parts by mass, respectively. A photocatalyst coating liquid was prepared in the same manner as in Example 1 except that 52.5 parts by mass and 17.5 parts by mass were used. Moreover, the total solid content concentration in terms of oxide in the obtained photocatalyst coating liquid was 5 parts by mass with respect to 100 parts by mass of the photocatalyst coating liquid.

The niobium oxide sol particles, colloidal silica particles, and the total content thereof were 57 parts by mass, 300 parts by mass, and 357 parts by mass, respectively, in terms of oxide with respect to 100 parts by mass of ethyl silicate in terms of oxide. It was. The total content of niobium oxide sol particles, colloidal silica particles, and ethyl silicate in terms of oxide was 400 parts by mass in terms of oxide with respect to 100 parts by mass of platinum-supported tungsten oxide particles.

(Comparative Example 4)
The content of platinum-supported tungsten oxide particles, niobium oxide sol particles, colloidal silica particles, and ethyl silicate in 100 parts by mass of the total solid content in terms of oxide in the photocatalyst coating liquid is 20 parts by mass and 20 parts by mass, respectively. A photocatalyst coating liquid was prepared in the same manner as in Example 1 except that the content was 45 parts by mass and 15 parts by mass. Moreover, the total solid content concentration in terms of oxide in the obtained photocatalyst coating liquid was 5 parts by mass with respect to 100 parts by mass of the photocatalyst coating liquid.

The niobium oxide sol particles, colloidal silica particles, and the total content thereof were 133 parts by mass, 300 parts by mass, and 433 parts by mass, respectively, in terms of oxide with respect to 100 parts by mass of ethyl silicate in terms of oxide. It was. The total content of niobium oxide sol particles, colloidal silica particles, and ethyl silicate in terms of oxide was 400 parts by mass in terms of oxide with respect to 100 parts by mass of platinum-supported tungsten oxide particles.

(Comparative Example 5)
The content of platinum-supported tungsten oxide particles, niobium oxide sol particles, colloidal silica particles, and ethyl silicate in 100 parts by mass of the total solid content in terms of oxide in the photocatalyst coating liquid is 20 parts by mass and 30 parts by mass, respectively. A photocatalyst coating liquid was prepared in the same manner as in Example 1 except that the amount was 37.5 parts by mass and 12.5 parts by mass. Moreover, the total solid content concentration in terms of oxide in the obtained photocatalyst coating liquid was 5 parts by mass with respect to 100 parts by mass of the photocatalyst coating liquid.

The niobium oxide sol particles, colloidal silica particles, and the total content thereof were 240 parts by mass, 300 parts by mass, and 540 parts by mass, respectively, in terms of oxides with respect to 100 parts by mass of ethyl silicate in terms of oxides. It was. The total content of niobium oxide sol particles, colloidal silica particles, and ethyl silicate in terms of oxide was 400 parts by mass in terms of oxide with respect to 100 parts by mass of platinum-supported tungsten oxide particles.

(Comparative Example 6)
The content of platinum-supported tungsten oxide particles, niobium oxide sol particles, colloidal silica particles, and ethyl silicate in 100 parts by mass of the total solid content in terms of oxide in the photocatalyst coating liquid is 20 parts by mass and 0 parts by mass, respectively. A photocatalyst coating liquid was prepared in the same manner as in Example 1 except that the amount was 65 parts by mass and 15 parts by mass. Moreover, the total solid content concentration in terms of oxide in the obtained photocatalyst coating liquid was 5 parts by mass with respect to 100 parts by mass of the photocatalyst coating liquid.

The niobium oxide sol particles, colloidal silica particles, and the total content thereof were 0 parts by mass, 433 parts by mass, and 433 parts by mass, respectively, in terms of oxide with respect to 100 parts by mass of ethyl silicate in terms of oxide. It was. The total content of niobium oxide sol particles, colloidal silica particles, and ethyl silicate in terms of oxide was 400 parts by mass in terms of oxide with respect to 100 parts by mass of platinum-supported tungsten oxide particles.

Using the photocatalyst coating liquid obtained above, a photocatalyst layer was prepared in the same manner as in Example 1, and the pencil hardness was measured to be 5-6H. Further, when the adhesion of the photocatalyst layer was examined using an adhesive cellophane tape, the photocatalyst layer was not peeled and the adhesion was good, but the limit contact angle was measured in the same manner as in Example 1. Then, it was 20 degrees.

(Comparative Example 7)
The content of platinum-supported tungsten oxide particles, niobium oxide sol particles, colloidal silica particles, and ethyl silicate in 100 parts by mass of the total solid content in terms of oxide in the photocatalyst coating liquid is 25 parts by mass and 10 parts by mass, respectively. A photocatalyst coating liquid was prepared in the same manner as in Example 1 except that the content was 65 parts by mass and 0 parts by mass. Moreover, the total solid content concentration in terms of oxide in the obtained photocatalyst coating liquid was 5 parts by mass with respect to 100 parts by mass of the photocatalyst coating liquid.

The total content of niobium oxide sol particles, colloidal silica particles, and oxide-converted ethyl silicate was 300 parts by mass in terms of oxide with respect to 100 parts by mass of platinum-supported tungsten oxide particles.

(Example 6)
When the photocatalytic activity of the photocatalyst layer formed using the photocatalyst coating liquid obtained in Example 1 was evaluated, the first-order rate constant was 0.11 h ⁻¹ .

(Reference Example 1)
By applying the photocatalyst coating liquid obtained in Examples 1 to 5 to the surface of the ceiling material constituting the ceiling and drying it, a photocatalyst layer can be formed on the surface of the ceiling material. By irradiating with light, the concentration of volatile organic substances (for example, formaldehyde, acetaldehyde, acetone, toluene, etc.) and malodorous substances in indoor spaces can be reduced, and pathogenic bacteria such as Staphylococcus aureus and Escherichia coli can be killed. In addition, allergens such as mite allergens and cedar pollen allergens can be rendered harmless. Furthermore, the surface of the ceiling material becomes hydrophilic, so that dirt can be easily wiped off, and further, charging can be prevented.

(Reference Example 2)
By applying and drying the photocatalyst coating liquid obtained in Examples 1 to 5 on the tiles applied to the indoor wall surface, a photocatalyst layer can be formed on the tile surface. Light irradiation can reduce the concentration of volatile organic substances (for example, formaldehyde, acetaldehyde, acetone, toluene, etc.) and malodorous substances in indoor spaces, can kill pathogenic bacteria such as Staphylococcus aureus and Escherichia coli, Allergens such as mite allergens and cedar pollen allergens can also be rendered harmless. Furthermore, the surface of the tile becomes hydrophilic, so that dirt can be easily wiped off, and charging can be prevented.

(Reference Example 3)
By applying the photocatalyst coating liquid obtained in Examples 1 to 5 to the indoor side surface of the window glass and drying, a photocatalyst layer can be formed on the glass surface, whereby light irradiation by indoor lighting is performed. Can reduce the concentration of volatile organic substances (for example, formaldehyde, acetaldehyde, acetone, toluene, etc.) and malodorous substances in indoor spaces, and can kill pathogenic bacteria such as Staphylococcus aureus and Escherichia coli. And allergens such as cedar pollen allergens can also be rendered harmless. Further, the surface of the window glass becomes hydrophilic, so that dirt can be easily wiped off, and further charging can be prevented.

(Reference Example 4)
By applying the photocatalyst coating liquid obtained in Examples 1 to 5 to the wallpaper and drying it, a photocatalyst layer can be formed on the surface of the wallpaper. In addition, the concentration of volatile organic substances (for example, formaldehyde, acetaldehyde, acetone, toluene, etc.) and malodorous substances in indoor spaces can be reduced by light irradiation by indoor lighting, and pathogenic bacteria such as Staphylococcus aureus and Escherichia coli can be killed. It is also possible to detoxify allergens such as mite allergens and cedar pollen allergens. Furthermore, the surface of the wallpaper becomes hydrophilic, so that dirt can be easily wiped off, and charging can be prevented.

(Reference Example 5)
By applying the photocatalyst coating liquid obtained in Examples 1 to 5 to the indoor floor surface and drying, a photocatalyst layer can be formed on the floor surface, and thus, indoors can be formed by light irradiation with indoor lighting. It can reduce the concentration of volatile organic substances (for example, formaldehyde, acetaldehyde, acetone, toluene, etc.) and malodorous substances in the space, kill pathogenic bacteria such as Staphylococcus aureus and Escherichia coli, and mite allergens and cedar Allergens such as pollen allergens can also be rendered harmless. Furthermore, the surface of the floor becomes hydrophilic, so that dirt can be easily wiped off and charging can be prevented.

(Reference Example 6)
By applying and drying the photocatalyst coating liquid obtained in Examples 1 to 5 on the surface of automobile interior materials such as an instrument panel for automobiles, an automobile seat, an automobile ceiling material, and an inside of an automobile glass. A photocatalyst layer can be formed on the surface of these automobile interior materials, and by this, the concentration of volatile organic substances (for example, formaldehyde, acetaldehyde, acetone, toluene, etc.) and malodorous substances in the interior space of the vehicle by light irradiation by interior lighting Pathogens such as Staphylococcus aureus and Escherichia coli can be killed, and allergens such as mite allergens and cedar pollen allergens can be rendered harmless. Furthermore, the surface of the automobile interior material becomes hydrophilic, so that dirt can be easily wiped off, and charging can be prevented.

(Reference Example 7)
By applying the photocatalyst coating liquid obtained in Examples 1 to 5 to the surface of the air conditioner and drying it, a photocatalyst layer can be formed on the surface of the air conditioner. It can reduce the concentration of volatile organic substances (for example, formaldehyde, acetaldehyde, acetone, toluene, etc.) and malodorous substances in the space, kill pathogenic bacteria such as Staphylococcus aureus and Escherichia coli, and mite allergens and cedar Allergens such as pollen allergens can also be rendered harmless. Furthermore, the surface of the air conditioner becomes hydrophilic, so that dirt can be easily wiped off, and charging can be prevented.

(Reference Example 8)
A photocatalyst layer can be formed in the refrigerator by applying the photocatalyst coating liquid obtained in Examples 1 to 5 to the refrigerator and drying it. Can reduce the concentration of volatile organic substances (such as ethylene) and malodorous substances in the refrigerator by light irradiation, and can kill pathogenic bacteria such as Staphylococcus aureus and Escherichia coli, and mite allergens and cedar pollen Allergens such as allergens can also be rendered harmless. Furthermore, the surface in the refrigerator compartment becomes hydrophilic, so that dirt can be easily wiped off and charging can be prevented.

(Reference Example 9)
By applying and drying the photocatalyst coating liquid obtained in Examples 1 to 5 on the surface of a substrate that is in contact with an unspecified number of people, such as a touch panel, a train strap, and an elevator button, these substrate surfaces are dried. A photocatalyst layer can be formed on the inside, thereby reducing the concentration of volatile organic substances (for example, formaldehyde, acetaldehyde, acetone, toluene, etc.) and malodorous substances in the indoor space by light irradiation by indoor lighting, Pathogens such as Staphylococcus aureus and Escherichia coli can be killed, and allergens such as mite allergens and cedar pollen allergens can be rendered harmless. Further, the surface of the base material becomes hydrophilic, so that dirt can be easily wiped off, and charging can be prevented.

Claims

(1) photocatalyst particles,
(2) niobium oxide sol particles,
(3) colloidal silica particles,
(4) silicon alkoxide, and (5) a photocatalyst coating liquid containing a solvent,
The oxide equivalent content of (2) is 0 to 200 parts by mass with respect to 100 parts by mass of the oxide equivalent of (4),
The oxide equivalent content of (3) is 0 to 280 parts by mass with respect to 100 parts by mass of the oxide equivalent of (4),
The total of the oxide equivalent contents of (2) and (3) is 0 to 480 parts by mass with respect to 100 parts by mass of the oxide equivalent of (4),
The total of the oxide equivalent content of (2), (3) and (4) is 20 to 500 parts by mass with respect to 100 parts by mass of (1),
The content in terms of solid oxide obtained by volatilizing a volatile component from the photocatalyst coating liquid is 0.5 to 30 parts by mass with respect to 100 parts by mass of the photocatalyst coating liquid. A photocatalyst coating liquid for forming a photocatalyst layer having photocatalytic activity.
The photocatalyst coating liquid according to claim 1, wherein the photocatalyst layer exhibits photocatalytic activity at least by irradiation with visible light.
The photocatalyst body coating liquid according to claim 1 or 2, wherein the photocatalyst body particles are tungsten oxide particles.
The photocatalyst coating liquid according to any one of claims 1 to 3, wherein the photocatalyst particles carry a noble metal.
A photocatalytic function product comprising a photocatalyst layer on a substrate surface, wherein the photocatalyst layer is formed using the photocatalyst coating liquid according to any one of claims 1 to 4. Product.