JP2020179342A - Photocatalyst spray, manufacturing method of photocatalyst spray, and manufacturing method of photocatalyst body - Google Patents

Abstract

To provide a photocatalyst spray excellent in water proofness and durability, while maintaining photocatalytic activity.SOLUTION: A photocatalyst spray contains photocatalyst particles, a binder and a solvent, and can be used over a long period, since the photocatalyst particles contain at least tungsten oxide, the binder contains a hydrolysate of a water-soluble silane coupling agent having an ethylene oxide structure, and further the solvent preferably contains ethanol and water.SELECTED DRAWING: None

Description

The present invention relates to a photocatalyst spray, a method for producing a photocatalyst spray, and a method for producing a photocatalyst.

Generally, deodorizing techniques are roughly classified into four main categories: chemical deodorization, physical deodorization, biological deodorization, and sensory deodorization. Among them, the chemical deodorization method is a method in which the odorous component and the deodorant component are made odorless by a chemical reaction (neutralization, addition, condensation, oxidation, etc.), and the target of the odor is known. It exerts an excellent effect when it is present.
As one of the chemical deodorizing methods, a deodorizing material utilizing the strong oxidizing power of a photocatalyst has been developed. Many deodorant materials using photocatalysts have been proposed conventionally.
For example, an antibacterial / deodorant material formed by dispersing and adhering metal particles selected from nanometer-order metallic silver and metallic copper particles to photocatalytic anatase-type titanium oxide particles shall be composed and contained. A spray characterized by the above has been proposed (see Patent Document 1).
Further, for example, an antibacterial deodorant spray composition containing alcohol, water, and a propellant using a hydrolyzable silane compound containing a guanidine group as an antibacterial component has been proposed (see Patent Document 2).

Japanese Patent No. 4979151 Japanese Patent No. 3191608

However, since the photocatalyst disclosed in Patent Document 1 is anatase-type titanium oxide, the photocatalyst cannot be activated by visible light other than ultraviolet light, and the effect is insufficient.
In the hydrolyzable silane compound containing a guanidyl group disclosed in Patent Document 2, the alkoxy group in the hydrolyzable silane compound reacts with water in the air (and water in the solvent) to hydrolyze and hydrolyze, resulting in a siloxane bond (siloxane document 2). A film of a siloxane polymer containing a guanidyl group having antibacterial and antihydrolytic activity is formed on the surface of the substrate by binding to an adjacent molecule and a hydroxyl group on the surface of the substrate via Si—O). However, since it does not contain a photocatalyst, it could not be deodorized by decomposing the components that cause the odor.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a photocatalytic spray having excellent water resistance and durability while maintaining photocatalytic activity.

As a result of various studies to achieve the above object, the present inventor has solved the above problems by using a photocatalyst spray containing photocatalytic particles and a hydrolyzate of a water-soluble silane coupling agent as a binder, and ethanol and water as a solvent. The present invention was completed by finding that the above can be solved.
Further, according to the present invention, there is provided a photocatalytic spray characterized in that the photocatalytic particles contain at least tungsten oxide.

Further, according to the present invention, the binder is provided with a photocatalytic spray characterized by containing a hydrolyzate of a water-soluble silane coupling agent having an amine structure.

Further, according to the present invention, the binder is provided with a photocatalytic spray characterized by containing a hydrolyzate of a water-soluble silane coupling agent having an ethylene oxide structure.

The photocatalytic layer constructed by the photocatalyst spray of the present invention has excellent water resistance and durability while maintaining photocatalytic activity, and can be used for a long period of time.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments. The present invention can be carried out with appropriate modifications within the scope of the object of the present invention. The description may be omitted as appropriate for the parts where the explanations overlap, but the gist of the invention is not limited.

<First Embodiment: Photocatalytic spray>
The first embodiment of the present invention relates to a photocatalytic spray (hereinafter, may be referred to as "spray"). The spray of the first embodiment contains at least a photocatalytic particle, a binder composed of a hydrolyzate of a water-soluble silane coupling agent, and ethanol and water as solvents. The spray may further contain additives such as preservatives, if desired. The spray of the first embodiment is an aqueous spray containing ethanol and water. Since an aqueous solvent can be used by using a water-soluble binder, the environmental load can be reduced and the working environment can be improved.

(binder)
The binder binds the base material to which the spray is sprayed to the photocatalytic particles. The binder contains at least one of a water-soluble hydrolyzate of a silane coupling agent having an ethylene oxide structure and a water-soluble hydrolyzate of a silane coupling agent having an amine structure. Hereinafter, the "silane coupling agent having an ethylene oxide structure" may be referred to as "silane coupling agent X", and the "silane coupling agent having an amine structure" may be referred to as "silane coupling agent X'". Further, "water-soluble hydrolyzate of a silane coupling agent having an ethylene oxide structure" is referred to as "hydrolyzate Y", and "water-soluble hydrolyzate of a silane coupling agent having an amine structure" is referred to as "hydrolyzate". Decomposition product Y'", may be described.

The silane coupling agent X has at least a silicon atom, an alkoxy group bonded to the silicon atom, and a group having an ethylene oxide structure bonded to the silicon atom. Hydrolyzate Y is a hydrolyzate of the silane coupling agent X. Hydrolyzate Y is obtained by hydrolyzing the silane coupling agent X. When the silane coupling agent X is hydrolyzed, the alkoxy group bonded to the silicon atom is hydrolyzed to form a hydroxy group bonded to the silicon atom. Then, a hydrolyzate Y having at least a silicon atom, a hydroxy group bonded to the silicon atom (that is, a silanol group, Si—OH), and a group having an ethylene oxide structure bonded to the silicon atom is obtained.

The silane coupling agent X'has at least a silicon atom, an alkoxy group bonded to the silicon atom, and a group having an amine structure bonded to the silicon atom. The hydrolyzate Y'is a hydrolyzate of the silane coupling agent X'. Hydrolyzate Y'is obtained by hydrolyzing the silane coupling agent X'. When the silane coupling agent X'is hydrolyzed, the alkoxy group bonded to the silicon atom is hydrolyzed to form a hydroxy group bonded to the silicon atom. Then, a hydrolyzate Y'having at least a silicon atom, a hydroxy group bonded to the silicon atom (that is, a silanol group, Si-OH), and a group having an amine structure bonded to the silicon atom is obtained.

When the binder contains the hydrolysates Y and Y', the following first to fourth advantages can be obtained. First, the first advantage will be described. When the components are dried by spraying the spray onto the base material, a part of the silanol groups of the hydrolyzate Y and the hydroxy groups on the surface of the base material are dehydrated and condensed, and between the hydrolyzate Y and the base material. A chemical bond is formed in. At the same time, a part of the silanol group of the hydrolyzate Y or Y ′ and the hydroxy group on the surface of the photocatalyst particles are dehydrated and condensed to form a chemical bond between the hydrolyzate Y or Y ′ and the photocatalyst particle. Will be done. By inducing these dehydration condensations, when the spray is sprayed onto the base material to dry the components, the photocatalytic particles and the base material can be firmly bonded to each other via a binder containing the hydrolyzate Y or Y ′. By binding tightly, the water resistance and durability of the photocatalyst layer formed by spraying can be improved.

Next, the second advantage will be described. When the components are dried by spraying the spray onto the substrate, some of the silanol groups of the hydrolysates Y and Y'are dehydrated and condensed with each other, so that the hydrolysates Y are bonded to each other. Further, in the hydrolyzate Y, the ethylene oxide structures are ring-opened and bonded to each other, so that the hydrolyzates Y are bonded to each other. By binding the hydrolyzates Y and Y'to each other in this way, when the spray is sprayed onto the base material and the components are dried, the photocatalyst particles and the base material are passed through a binder containing the hydrolyzates Y and Y'. Can be more firmly combined with. By binding tightly, the water resistance and durability of the photocatalyst layer formed by spraying can be improved.

Next, the third advantage will be described. Having an ethylene oxide structure or an amine structure enhances the affinity of the hydrolysates Y and Y'for water. Due to the high affinity for water, the hydrolysates Y and Y'are more compatible with water-containing water-based sprays.

Next, the fourth advantage will be described. Generally, when the spray is sprayed onto the substrate to dry the components, dehydration condensation of the hydrolyzate of the silane coupling agent is triggered. Generally, it takes a certain amount of time to hydrolyze the silane coupling agent. However, the spray of the first embodiment contains hydrolysates Y and Y'hydrolyzed by the silane coupling agents X and X'. Therefore, when the spray is sprayed on the base material to dry the components, only the dehydration condensation of the hydrolysates Y and Y'is caused, and the hydrolysis can be omitted. Therefore, the time required for hydrolysis can be omitted, and the time required for producing the photocatalyst described later in the third embodiment can be shortened. Moreover, since ethanol is contained in addition to water as a solvent, it is easy to dry and the drying time can be shortened.

Hydrolysates Y and Y'have water solubility. Since the hydrolysates Y and Y'are water-soluble, the hydrolysates Y and Y'can be stably present in a water-containing spray. In the present specification, the hydrolyzate Y or Y'is water-soluble when 5 parts by weight of the hydrolyzate Y or Y'is added to 95 parts by weight of water in an environment of 25 ° C. It means that the decomposition products Y and Y'dissolve in water. Whether or not the hydrolysates Y and Y'are dissolved in water can be visually confirmed.

The ethylene oxide structure of the silane coupling agent X is represented by the following chemical formula (2). A preferable example of the silane coupling agent X having an ethylene oxide structure is a silane coupling agent X having an epoxy group. The epoxy group is represented by the following chemical formula (2-1). In the chemical formula (2-1), * represents a bond. Further, as another preferable example of the silane coupling agent X having an ethylene oxide structure, there is a silane coupling agent X having a condensed ring group in which ethylene oxide and cycloalkane having 3 or more carbon atoms are condensed. Such a fused ring group is represented by the following chemical formula (2-2). In the chemical formula (2-2), p and q each independently represent an integer of 0 or more, and * represents a bond. In the chemical formula (2-2), p preferably represents an integer of 0 or more and 5 or less, and more preferably represents 1. q preferably represents an integer of 0 or more and 5 or less, and more preferably represents 2.

The silane coupling agent X is preferably a silane coupling agent represented by the general formula (1X). Hereinafter, the "silane coupling agent represented by the general formula (1X)" may be referred to as "silane coupling agent (1X)".

In the general formula (1X), R ¹ represents an alkoxy group. R ² represents an alkyl group. R ³ represents an alkylene group. m represents an integer of 1 or more and 3 or less. E represents a group represented by the general formula (E1) or (E2).

In the general formula (E1), R ⁴ represents an alkylene group, and * represents a bond that binds to R ³ . In the general formula (E2), * represents a bond that binds to R ³ . The silane coupling agent (1X) in which E in the general formula (1X) represents a group represented by the general formula (E1) is a suitable example of the silane coupling agent X having an epoxy group. The silane coupling agent (1X) in which E in the general formula (1X) represents a group represented by the general formula (E2) is a condensed ring group in which the above ethylene oxide and cycloalkane having 3 or more carbon atoms are condensed. It is a preferable example of the silane coupling agent X having.

The alkoxy group represented by R ¹ in the general formula (1X) is linear or branched and is unsubstituted. As the alkoxy group represented by R ¹ in the general formula (1X), an alkoxy group having 1 to 6 carbon atoms is preferable, an alkoxy group having 1 to 3 carbon atoms is more preferable, and a methoxy group or an ethoxy group is further used. preferable.

The alkyl group represented by R ² in the general formula (1X) is linear or branched and is unsubstituted. As the alkyl group represented by R ² in the general formula (1X), an alkyl group having 1 to 6 carbon atoms is preferable, an alkyl group having 1 to 3 carbon atoms is more preferable, and a methyl group or an ethyl group is further preferable. preferable.

The alkylene group represented by R ³ in the general formula (1X) is linear or branched and is unsubstituted. As the alkylene group represented by R ³ in the general formula (1X), an alkylene group having 1 or more and 6 or less carbon atoms is preferable, an alkylene group having 1 or more and 3 or less carbon atoms is more preferable, and a methylene group (-CH ₂ −). ), Ethylene group (-CH _2- CH _2- ), or propylene group (-CH _2- CH _2- CH _2- ) is more preferable, and propylene group (-CH _2- CH _2- CH _2- ) is particularly preferable. ..

When m in general formula (1X) is 2 or 3, two or three R ¹ may be the same or different from each other. When m in the general formula (1X) is 1, the two R ^2s may be the same or different from each other. M in the general formula (1X) preferably represents 2 or 3, and more preferably 3.

Alkylene group R ⁴ represents in the general formula (E1) is a straight-chain or branched, is unsubstituted. The alkylene group R ⁴ represents in the general formula (E1), preferably an alkylene group having 1 to 6 carbon atoms, more preferably an alkylene group having 1 to 3 carbon atoms, a methylene group (-CH ₂ - ), Ethylene group (-CH _2- CH _2- ), or propylene group (-CH _2- CH _2- CH _2- ) is more preferable, and methylene group (-CH _2- ) is particularly preferable.

Examples of the silane coupling agent X include γ-glycidoxypropyltrimethoxysilane (that is, 3-glycidoxypropyltrimethoxysilane), γ-glycidoxypropyltriethoxysilane, and γ-glycidoxypropyldimethoxy. Methylsilane, γ-glycidoxypropyldiethoxymethylsilane, γ-glycidoxypropylethoxydimethylsilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl Examples thereof include triethoxysilane and 5,6-epoxyhexyl triethoxysilane. Preferable examples of the silane coupling agent X include 3-glycidoxypropyltrimethoxysilane.

The hydrolyzate Y is preferably a hydrolyzate represented by the general formula (1Y). Hereinafter, the "hydrolyzate represented by the general formula (1Y)" may be referred to as "hydrolyzate (1Y)". The hydrolyzate (1Y) is obtained by hydrolyzing the silane coupling agent (1X). In the general formula ^{(1Y) R 2, R 3} , m, and E are each, formula (1X) ^R 2 ^{in, R} 3, m, and is synonymous with E.

Examples of the hydrolyzate Y include γ-glycidoxypropyltrihydroxysilane (that is, 3-glycidoxypropyltrihydroxysilane), γ-glycidoxypropyltrihydroxysilane, and γ-glycidoxypropyldihydroxymethyl. Silane, γ-glycidoxypropyl dihydroxymethylsilane, γ-glycidoxypropylhydroxydimethylsilane, β- (3,4-epoxycyclohexyl) ethyltrihydroxysilane, β- (3,4-epoxycyclohexyl) ethyltrihydroxy Examples include silane and 5,6-epoxyhexyltrihydroxysilane. Preferable examples of the hydrolyzate Y include 3-glycidoxypropyltrihydroxysilane.

As the silane coupling agent X, a commercially available product may be used. Examples of commercially available silane coupling agent X include KBM-403 (3-glycidoxypropyltrimethoxysilane) and KBE-403 (3-glycidoxypropyltriethoxy) sold by Shin-Etsu Chemical Co., Ltd. Silane), and KBM-303 (2- (3,4-epylcyclohexyl) ethyltrimethoxysilane). As another example of the commercially available silane coupling agent X, Silkest A-187 (3-glycidoxypropyltrimethoxysilane) and Silkest A-1871 (3-1871) sold by Momentive Performance Materials Co., Ltd. Glycydoxypropyltriethoxysilane) and Silkgest A-186 (2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane). As another example of the commercially available silane coupling agent X, Dynasylan GLYMO (3-glycidoxypropyltrimethoxysilane) and Dynasylan GLYEO (3-glycidoxypropyltri) sold by Evonik Degussa Japan Co., Ltd. Ethoxysilane). As another example of the commercially available silane coupling agent X, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyl (dimethoxy) methylsilane, and triethoxy (3-glycidyloxy) sold by Tokyo Chemical Industry Co., Ltd. Examples thereof include propyl) silane and diethoxy (3-glycidyloxypropyl) methylsilane. After hydrolyzing these silane coupling agents X, the obtained hydrolyzate Y can be added to the spray. Further, as the hydrolyzate Y, a commercially available product may be used. An example of a commercially available hydrolyzate Y is Dynasylan SIVO110 sold by Evonik Degussa Japan Co., Ltd. Since this hydrolyzate Y has already been hydrolyzed, it can be added to the spray without being hydrolyzed.

The amine structure of the silane coupling agent X'is represented by the following chemical formula (2). Preferable examples of the silane coupling agent X'having an amine structure include a silane coupling agent X'having an amino group, which has a primary amino group and a secondary amino group at the chain and / or at the end. Contains. In the formula, R1 to R3 represent hydrogen or alkyl groups.

The silane coupling agent X'is preferably a silane coupling agent represented by the general formula (1X'). Hereinafter, the "silane coupling agent represented by the general formula (1X')" may be described as "silane coupling agent (1X')".

In the general formula (1X'), R ¹ represents an alkoxy group. R ² represents an alkyl group. R ³ represents an alkylene group. m represents an integer of 1 or more and 3 or less. E represents a group represented by the general formula (E1) or (E2).

一般式（Ｅ１）（Ｅ２）中、＊はＲ３に結合する結合手を表し、Ｒ^４はアルキレン基を表す。

In Formula (E1) (E2), * represents a bond that binds to R3, ^{R 4} represents an alkylene group.

The alkoxy group represented by R ¹ in the general formula (1X') is linear or branched and is unsubstituted. As the alkoxy group represented by R ¹ in the general formula (1X'), an alkoxy group having 1 to 6 carbon atoms is preferable, an alkoxy group having 1 to 3 carbon atoms is more preferable, and a methoxy group or an ethoxy group is used. More preferred.

The alkyl group represented by R ² in the general formula (1X') is linear or branched and is unsubstituted. The general formula (1X') alkyl group R ² represents in, preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, a methyl group or an ethyl group More preferred.

The alkylene group represented by R ³ in the general formula (1X') is linear or branched and is unsubstituted. As the alkylene group represented by R ³ in the general formula (1X'), an alkylene group having 1 or more and 6 or less carbon atoms is preferable, an alkylene group having 1 or more and 3 or less carbon atoms is more preferable, and a methylene group (-CH _2). -), Ethylene group (-CH _2- CH _2- ), or propylene group (-CH _2- CH _2- CH _2- ) is more preferable, and propylene group (-CH _2- CH _2- CH _2- ) is particularly preferable. preferable.

When m in formula (1X') is 2 or 3, two or three R ¹ may be the same or different from each other. When m in formula (1X') is 1, two R ² may be the same or may be different from each other. M in the general formula (1X') preferably represents 2 or 3, and more preferably 3.

Alkylene group R ⁴ represents in the general formula (E1) is a straight-chain or branched, is unsubstituted. The alkylene group R ⁴ represents in the general formula (E1), preferably an alkylene group having 1 to 6 carbon atoms, more preferably an alkylene group having 1 to 3 carbon atoms, a methylene group (-CH ₂ - ), Ethylene group (-CH _2- CH _2- ), or propylene group (-CH _2- CH _2- CH _2- ) is more preferable, and ethylene group (-CH _2- CH _2- ) is particularly preferable.

Examples of the silane coupling agent X'are 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (amino). Ethyl) -3-aminopropyltrimethoxysilane, 3- (2-aminoethylaminopropyl) triethoxysilane and 3- [2- (2-aminoethylaminoethylamino) propyl] trimethoxysilane. A preferred example of the silane coupling agent X'is 3-aminopropyltrimethoxysilane.

The hydrolyzate Y'is preferably a hydrolyzate represented by the general formula (1Y'). Hereinafter, the "hydrolyzate represented by the general formula (1Y')" may be referred to as "hydrolyzate (1Y')". The hydrolyzate (1Y') is obtained by hydrolyzing the silane coupling agent (1X'). Formula ^R 2 in ^{(1Y'), R 3, m} , and E are each the same meaning as the general formula ^R 2 in ^{(1X'), R 3, m} , and E.

Examples of the hydrolyzate Y'include γ-glycidoxypropyltrihydroxysilane (that is, 3-glycidoxypropyltrihydroxysilane), γ-glycidoxypropyltrihydroxysilane, and γ-glycidoxypropyldihydroxy. Methylsilane, γ-glycidoxypropyldihydroxymethylsilane, γ-glycidoxypropylhydroxydimethylsilane, β- (3,4-epoxycyclohexyl) ethyltrihydroxysilane, β- (3,4-epoxycyclohexyl) ethyltri Hydroxysilane, and 5,6-epoxyhexyltrihydroxysilane _, 3-aminopropyltrihydroxysilane, N-2- (aminoethyl) -3-aminopropylmethyldihydroxysilane, 3- (2-aminoethylaminopropyl) tri Hydroxylsilane and 3- [2- (2-aminoethylaminoethylamino) propyl] trihydroxysilane can be mentioned. A preferred example of the hydrolyzate Y'is 3-aminopropyltrihydroxysilane.

As the silane coupling agent X', a commercially available product may be used. Examples of commercially available silane coupling agents X'are KBM-403 (3-glycidoxypropyltrimethoxysilane) and KBE-403 (3-glycidoxypropyltri) sold by Shin-Etsu Chemical Co., Ltd. Ethoxysilane) and KBM-303 (2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane). As another example of the commercially available silane coupling agent X', Silkuest A-187 (3-glycidoxypropyltrimethoxysilane) and Silkquest A-1871 (3) sold by Momentive Performance Materials Co., Ltd. -Glycydoxypropyltriethoxysilane), and Silkgest A-186 (2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane). As another example of the commercially available silane coupling agent X', Dynasylan GLYMO (3-glycidoxypropyltrimethoxysilane) and Dynasylan GLYEO (3-glycidoxypropyl) sold by Evonik Degussa Japan Co., Ltd. Triethoxysilane). As another example of the commercially available silane coupling agent X', 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyl (dimethoxy) methylsilane, and triethoxy (3-glycidyl) sold by Tokyo Chemical Industry Co., Ltd. Examples thereof include oxypropyl) silane and diethoxy (3-glycidyloxypropyl) methylsilane. After hydrolyzing these silane coupling agents X', the obtained hydrolyzate Y'can be added to the spray. Further, as the hydrolyzate Y', a commercially available product may be used. An example of a commercially available hydrolyzate Y'is Dynasylan SIVO110 sold by Evonik Degussa Japan Co., Ltd. Since this hydrolyzate Y has already been hydrolyzed, it can be added to the spray without being hydrolyzed.

The spray may contain only one hydrolyzate Y or Y', or may contain two or more hydrolysates. Further, the spray may contain only the hydrolyzate Y or Y', or may further contain a hydrolyzate of a silane coupling agent other than the hydrolyzate Y or Y'.

The components of the spray of the present invention are not particularly limited as long as they contain a binder containing photocatalytic particles and a hydrolyzate of a water-soluble silane coupling agent and a solvent containing ethanol and water, and can be sprayed in the form of a mist. In order to improve water resistance and durability while maintaining photocatalytic activity, the content of hydrolyzate Y or Y'is 0.5% by weight based on the weight of the total solid content contained in the spray. It is preferably 25% by weight or more. The total solid content contained in the spray is a component of the components contained in the spray, excluding the solvent (for example, water, ethanol).

Further, in order to particularly improve the photocatalytic activity while improving the water resistance and durability, the content of the hydrolyzate Y or Y'is 0.5 with respect to the weight of the total solid content contained in the spray. It is more preferably 0% by weight or more and 20% by weight or less, further preferably 0.5% by weight or more and 10% by weight or less, further preferably 0.5% by weight or more and 5% by weight or less, and 2% by weight. It is particularly preferable that it is% or more and 5% by weight or less. The hydrolyzate Y or Y'is dehydrated and condensed with the photocatalyst particles, and the hydrolyzate Y or Y'is dehydrated and condensed with the substrate, so that the photocatalyst particles and the substrate are routed through a binder containing the hydrolyzate Y or Y'. Strongly binds to. Therefore, even when the content of the hydrolyzate Y or Y'which is a binder is low, the photocatalyst particles and the base material are strongly bonded to each other via the binder. Therefore, the amount of the hydrolyzate Y or Y'which is a binder can be reduced. As a result, it is possible to suppress the damage of the photocatalytic activity of the photocatalyst layer by the binder and the embedding of the photocatalyst particles in the binder. As a result, the photocatalytic activity can be particularly improved while improving the water resistance and durability.

The role of ethanol in the solvent of the present invention is to reduce the viscosity of the spray liquid to maintain a fine spray state, and since ethanol has the property of being more volatile than water, the drying time of the spray liquid can be shortened by including it in the solvent. It can be shortened, and ethanol has a bactericidal action, which enables long-term storage of the spray solution.

The lower limit of the amount of ethanol blended in the spray solution solvent is preferably 1% by weight or more, and the upper limit is preferably 50% by weight or less. If the amount of ethanol blended in the solvent exceeds 50% by weight, it becomes difficult to maintain the photocatalyst-dispersed state during long-term storage. In addition to water and ethanol, the solvent may contain other alcohol components generated during hydrolysis of the water-soluble silane coupling agent used as a binder.

(Photocatalytic particles)
The photocatalytic particles have photocatalytic activity. Specifically, the photocatalytic particles are irradiated with light having an energy equal to or greater than the energy gap between the valence band and the conduction band. Upon irradiation with light, electrons in the valence band of the photocatalyst particles are excited in the conduction band, and holes are generated in the valence band. These electrons and holes move inside the photocatalytic particles. Superoxide anions are generated by the reduction of oxygen by electrons. Hydroxyl radicals are generated when holes oxidize water. Reactive oxygen species are generated by the generated hydroxyl radicals. Depending on the reactive oxygen species produced, for example, decomposition of harmful substances, antibacterial and antifouling are achieved.

Photocatalytic particles include, for example, titanium oxide, tungsten oxide, strontium titanate (SrTIO ₃ ), niobium oxide (Nb ₂ O ₅ ), tantalum oxide (Ta ₂ O ₅ ), zirconium oxide (ZrO ₂ ), bismuth oxide (Bi ₂ ). O _3), or preferably contains iron oxide _(Fe 2 _{O 3).} The spray may contain only one type of photocatalytic particles or may contain two or more types of photocatalytic particles. The photocatalytic particles preferably contain tungsten oxide in order to obtain a spray having excellent photocatalytic activity even under an indoor visible light source.

The tungsten oxide is not particularly limited, and a commercially available product can be appropriately used as the tungsten oxide. Examples of tungsten oxide include WO ₃ (tungsten trioxide), WO ₂ , WO, W ₂ O ₃ , W ₄ O ₅ , W ₄ O ₁₁ , W ₂₅ O ₇₃ , W ₂₀ O ₅₈ , and W ₂₄ O _68. , As well as mixtures thereof. WO ₃ is preferable as the tungsten oxide in order to improve the photocatalytic activity. A part of tungsten oxide may be reduced to V value. However, it is preferable to use tungsten oxide after oxidizing it to a VI value. Examples of the method of oxidizing to the VI value include a method of firing tungsten oxide at a high temperature. The crystal structure of tungsten oxide is not particularly limited.

The average particle size of the photocatalyst particles is preferably 5 nm or more and 200 nm or less. When the average particle diameter of the photocatalyst particles is 5 nm or more, the photocatalyst particles are less likely to aggregate and the photocatalyst particles can be easily redispersed. When the average particle size of the photocatalyst particles is 200 nm or less, the photocatalyst particles and other spray components tend to be uniformly mixed, and the photocatalyst particles can be suppressed from being separated from the photocatalyst layer formed by the spray. The average particle size of the photocatalyst particles is a value calculated based on the specific surface area (unit: m ² / g) of the photocatalyst particles measured by the BET method, assuming that the primary particles of the photocatalyst particles are spherical. is there. The method for measuring the average particle size of the photocatalytic particles will be described later in Examples.

Co-catalyst particles may be provided on the surface of the photocatalyst particles. As the co-catalyst particles, metal particles are preferable, transition metal particles are more preferable, and platinum group metal particles are further preferable. Examples of the platinum group metal particles include particles of Pt, Pd, Rh, Ru, Os, and Ir. By providing the co-catalyst particles on the surface of the photocatalyst particles, the energy gap between the valence band and the conduction band of the photocatalyst particles can be reduced, and the photoresponsiveness in the visible light region can be improved.

The content of the photocatalyst particles is preferably 75% by weight or more and 99% by weight or less, more preferably 80% by weight or more and 99% by weight or less, based on the weight of the total solid content contained in the spray. It is more preferably 90% by weight or more and 99% by weight or less, further preferably 95% by weight or more and 99% by weight or less, and particularly preferably 98% by weight or more and 99% by weight or less. The hydrolyzate Y dehydrates and condenses with the photocatalyst particles, and the hydrolyzate Y dehydrates and condenses with the base material, so that the photocatalyst particles and the base material are strongly bonded to each other via the binder containing the hydrolyzate Y. Therefore, when the content of the photocatalyst particles is high, in other words, even when the content of the binder is low, the photocatalyst particles and the base material are strongly bonded to each other via the binder. Therefore, the amount of hydrolyzate Y added as a binder can be reduced. As a result, it is possible to suppress the damage of the photocatalytic activity of the photocatalyst layer by the binder and the embedding of the photocatalyst particles in the binder. As a result, the photocatalytic activity can be particularly improved while improving the water resistance and durability.

(Spacer particles)
The spray may further contain spacer particles in addition to the photocatalytic particles, the binder, and the solvent containing water and ethanol. The spacer particles have an average particle size larger than the average particle size of the photocatalytic particles. When the photocatalytic particles contain a metal or metal oxide, the spacer particles contain a metal or metal oxide different from the photocatalyst particles. When the spray contains spacer particles, when the photocatalyst layer formed by the spray comes into contact with the photocatalyst layer or a member other than the photocatalyst layer by shaking or impact, the spacer particles contained in the photocatalyst layer cause friction and impact. To absorb. Therefore, the photocatalytic layer formed by spraying becomes strong against friction and impact, and the photocatalytic activity of the photocatalytic particles can be exhibited for a long time. Further, metals and metal oxides are less likely to be decomposed by photocatalytic particles as compared with resins which are organic polymers. Therefore, the spacer particles containing a metal and a metal oxide are excellent in durability.

The metal contained in the spacer particles is not particularly limited, but is preferably a metal of Group 10, Group 11, or Group 12 of the Periodic Table, and is one or more metals selected from the group consisting of silver, zinc, and copper. Is more preferable. The metal oxide contained in the spacer particles is not particularly limited, but is preferably an oxide of a metal of Group 10, Group 11, or Group 12 of the periodic table, and is one selected from the group consisting of silver, zinc, and copper. It is more preferable that it is an oxide of the above metal. Since such metals and metal oxides have antibacterial activity, both the photocatalytic activity of the photocatalytic particles and the antibacterial activity of the spacer particles can be imparted to the spray. In order to improve the antibacterial performance, the spacer particles preferably contain one or more metals selected from the group consisting of silver, zinc and copper or oxides thereof.

The average particle size of the spacer particles is preferably 200 nm or more and 1,000 nm or less. The average particle size of the spacer particles is a value calculated based on the specific surface area (unit: m ² / g) of the spacer particles measured by the BET method, assuming that the primary particles of the spacer particles are spherical. is there. The method for measuring the average particle size of the spacer particles will be described later in Examples.

When the spray contains spacer particles, the content of the spacer particles is preferably 0.1% by weight or more and 5.0% by weight or less, preferably 0.1% by weight, based on the weight of the total solid content of the spray. It is more preferably 2.0% by weight or less, and further preferably 0.1% by weight or more and 1.0% by weight or less.

(Additive)
Additives that the spray may contain include organic compounds that have an antiseptic effect. Examples of the organic compound having an antiseptic effect include butylparaben, propylparaben, ethylparaben, methylparaben, benzylparaben, isopropylparaben, isobutylparaben and the like. Further, an organic compound having an algae-proofing effect can be mentioned as a substance that exerts an effect after spraying and drying the spray on a base material. Examples of organic compounds having an algae-proofing effect include organic nitrogen-sulfur compounds, pyrithion compounds, organic iodine compounds, triazine compounds, isothiazoline compounds, imidazole compounds, pyridine compounds, nitrile compounds, and thiocarbamate compounds. , Thiazole-based compounds, and disulfide-based compounds.

<Second embodiment: Spray manufacturing method>
A second embodiment of the present invention relates to a method for producing a spray. The spray produced by the production method of the second embodiment is the spray of the first embodiment. The spray produced by the production method of the second embodiment is excellent in water resistance and durability while maintaining photocatalytic activity for the same reason as described in the first embodiment. The method for producing a spray of the second embodiment includes, for example, a spray preparation step. In the method for producing a spray of the second embodiment, a hydrolysis step may be further carried out before the spray preparation step. However, when a commercially available hydrolyzate Y or Y'is used, the hydrolysis step can be omitted.

(Hydrolyzed step)
In the hydrolysis step, the silane coupling agent X or X'is hydrolyzed to give the hydrolyzate Y or Y'. An example of a method of hydrolyzing the silane coupling agent X is a method of adding the silane coupling agent X or X'to water. Since the silane coupling agent X or X'has a structure having a high affinity for water, the silane coupling agent X can be hydrolyzed without adding an acid to water. However, in order to promote hydrolysis, the silane coupling agent X or X'may be hydrolyzed under acidic conditions by adding an acid to the water to which the silane coupling agent X or X'is added. Since it is difficult to dehydrate and condense, it is preferable to hydrolyze the silane coupling agent X or X'without heating.

(Spray preparation process)
In the spray preparation step, a binder containing the hydrolyzate Y or Y', photocatalytic particles, water and ethanol are mixed to obtain the spray of the first embodiment. In order to improve the dispersibility, it is preferable to mix the hydrolyzate Y or Y'and the photocatalytic particles after obtaining the hydrolyzate Y or Y'. The photocatalyst particles may be added in the form of a photocatalyst solution containing the photocatalyst particles and a solvent or a dispersion medium. Further, the binder may be added in the state of a binder solution containing the binder and a solvent or a dispersion medium and dried. As the binder solvent contained in the photocatalyst solution, for example, methanol, propanol and the like may be contained in addition to water and ethanol. In the hydrolysis step, when the silane coupling agent X is added to water to obtain an aqueous solution of the hydrolyzate Y or Y', the aqueous solution of the hydrolyzate Y or Y'is used as a binder solution. May be good. In the spray preparation step, additives may be further added and mixed.

<Third Embodiment: Method for producing a photocatalyst>
A third embodiment of the present invention relates to a method for producing a photocatalyst. In the method for producing a photocatalyst of the third embodiment, the spray of the first embodiment is used. Since the spray of the first embodiment is used, the photocatalyst produced by the production method of the third embodiment is water resistant while maintaining the photocatalytic activity for the same reason as described in the first embodiment. And excellent in durability. The photocatalyst body produced by the production method of the third embodiment includes a base material and a photocatalyst layer. The photocatalyst layer is provided on the substrate. The photocatalyst layer may be arranged directly on the substrate. Alternatively, a photocatalyst layer may be arranged on the substrate via a primer layer. The primer layer is formed by the primer. The method for producing a photocatalyst of the third embodiment includes, for example, a step of forming a photocatalyst layer.

(Photocatalyst layer forming process)
In the photocatalyst layer forming step, the spray of the first embodiment is sprayed on the base material and dried. By drying, the photocatalytic particles and the base material are bonded to each other via a binder containing the hydrolyzate Y or Y'. Drying removes at least a portion of the solvent (water and ethanol) contained in the spray. In this way, a photocatalyst layer containing photocatalyst particles, a binder containing the hydrolyzate Y or Y', and arbitrary spacer particles is formed on the substrate. Since the spray of the first embodiment contains a binder containing the hydrolyzate Y or Y', the photocatalyst layer can be formed without performing a hydrolysis treatment in the photocatalyst layer forming step.

The spray of the first embodiment contains a binder containing the hydrolyzate Y or Y'. By drying the spray, the hydrolyzate Y or Y'and the photocatalytic particles are dehydrated and condensed, and the hydrolyzate Y or Y'and the substrate are dehydrated and condensed. Due to the chemical bonds formed by these dehydration condensations, the photocatalytic particles and the base material are firmly bonded to each other via the binder. By tightly bonding, the water resistance and durability of the photocatalyst body including the photocatalyst layer formed by the spray of the first embodiment can be improved. In order to have excellent water resistance and durability, the photocatalyst produced by the production method of the third embodiment preferably exhibits photocatalytic activity in any environment such as indoors, outdoors, air, and water. Can be done.

Examples of the material of the base material (specifically, the support) include glass, plastic, metal, ceramics, wood, stone, cement, concrete, fiber, fabric, paper, and leather, and combinations thereof. .. The base material may be a laminate having a plurality of layers of different materials. The spray of the first embodiment contains the hydrolyzate Y or Y'as a binder. Therefore, even if the base material is such a material, the hydrolyzate Y or Y'and the base material are dehydrated and condensed, and the hydrolyzate Y or Y'and the photocatalyst particles are dehydrated and condensed. Due to the chemical bonds formed by these dehydration condensations, the photocatalytic particles and the base material are firmly bonded to each other via the binder.

The method of spraying the spray onto the substrate is not particularly limited. The contents are sprayed and used by sealing in a spray container equipped with a spray nozzle. As a result, the desired base material can be processed only by spraying without using a large-scale tool. Examples of the spray container include a trigger spray container and an aerosol spray container. In the case of an aerosol spray, LPG (liquefied propane gas), DME (dimethyl ether), carbon dioxide gas, nitrogen gas and the like may be used alone or in combination of two or more as a propellant. As a spray container, a trigger spray is preferable from the economical point of view that it can be used over and over again.
The spray may be sprayed on at least a part of the substrate. The thickness of the photocatalyst layer formed after spraying is not particularly limited. The effect of the spray of the first embodiment can be obtained regardless of the thickness of the photocatalyst layer obtained by any of the spray methods.

The method of drying the spray sprayed on the substrate is not particularly limited. Examples of the method for drying the spray sprayed on the base material include natural volatilization and forced drying using a heater.

It is preferable to modify the surface of the substrate to be hydrophilic before spraying the spray onto the substrate. By modifying the surface of the base material to be hydrophilic, the wettability of the spray to the base material can be improved, and a photocatalyst layer having a more uniform film thickness can be formed.

Examples of the method for modifying the surface of the base material to be hydrophilic include chemical treatment, mechanical treatment, corona treatment, flame treatment, ultraviolet irradiation treatment, high frequency treatment, glow discharge treatment, plasma treatment, laser treatment, mixed acid treatment, and the like. And ozone oxidation treatment.
Another example of the method of modifying the surface of the base material to be hydrophilic is a method of applying a primer layer on the base material to form a primer layer on the base material.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the examples. The "average particle size" described below was measured by the following method. Specifically, the specific surface area Sm of the measurement particles (for example, photocatalyst particles or spacer particles) per unit mass is measured using a specific surface area / pore distribution measuring device (“NOVA e series 4200e” manufactured by Cantachrome Instruments). did. Next, the average particle diameter d of the measured particles was calculated from the measured specific surface area Sm of the measured particles according to the following formula (1).
Average particle diameter d = 6 / (specific surface area Sm of measurement particles x density ρ of measurement particles) ... (1)

Table 1 shows the compositions of the spray contents (A-1) to (A-10) and (B-1) according to Examples and Comparative Examples.

“Pt-WO ₃ ” in Table 1 indicates platinum-supported tungsten oxide particles. Platinum-supported tungsten oxide particles, which are photocatalytic particles, were produced by the methods shown below. Specifically, 200 g of tungsten oxide (manufactured by Kishida Chemical Co., Ltd.) and 1000 mL of pure water were mixed and then dispersed while irradiating ultrasonic waves to obtain a dispersion liquid A of tungsten oxide particles. Hexachloroplatinic acid (VI) hexahydrate (manufactured by Kishida Chemical Co., Ltd., purity 98.5%) was dissolved in the dispersion solution A to obtain a dispersion solution B of tungsten oxide particles. The amount of hexachloroplatinum (VI) / hexahydrate added was such that the ratio of the weight of platinum alone to the weight of the tungsten oxide particles was 0.05% by weight. The dispersion B was heated at 100 ° C. to evaporate the water content, and then calcined at 500 ° C. to obtain platinum-supported tungsten oxide particles. The average particle size of the obtained platinum-supported tungsten oxide particles was 175 nm.

“3-Gly” in Table 1 indicates a hydrolyzate of 3-glycidoxypropyltrimethoxysilane. 3-Glycydoxypropyltrimethoxysilane is a silane coupling agent having an ethylene oxide structure. The hydrolyzate of 3-glycidoxypropyltrimethoxysilane, which is a binder, was prepared by hydrolyzing 3-glycidoxypropyltrimethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.) by the method described later.

When 5 parts by weight of 3-glycidoxypropyltrimethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to 95 parts by weight of water in an environment of 25 ° C., 3-glycidoxypropyltrimethoxysilane was added. It was visually confirmed that the decomposition product was dissolved in water.

“APTES” in Table 1 indicates a hydrolyzate of 3-aminopropyltrimethoxysilane. 3-Aminopropyltrimethoxysilane is a silane coupling agent having an amine structure. The hydrolyzate of 3-aminopropyltrimethoxysilane, which is a binder, was prepared by hydrolyzing 3-aminopropyltrimethoxysilane (manufactured by Tokyo Kasei Kogyo Co., Ltd.) by the method described later.

When 5 parts by weight of 3-aminopropyltrimethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to 95 parts by weight of water in an environment of 25 ° C., a hydrolyzate of 3-glycidoxypropyltrimethoxysilane. Was visually confirmed to be dissolved in water.

Pure water was used for "water" in Table 1, and ethyl alcohol was used for EtOH.
“-” In Table 1 indicates that the spray content does not contain the corresponding material.
“Content rate photocatalyst / binder” in Table 1 indicates “content rate of photocatalyst particles / content rate of binder”. The content of the photocatalyst particles indicates the content of the photocatalyst particles (unit: weight%) with respect to the weight of the total solid content of the spray contents. The binder content indicates the binder content (unit: weight%) with respect to the weight of the total solid content of the spray contents. The weight of the total solid content of the spray contents was calculated by the formula "weight of total solid content = amount of photocatalyst particles added + amount of binder added".

Hereinafter, the methods for producing the spray contents (A-1) to (A-10) and (B-1) shown in Table 1, the evaluation method, and the evaluation results will be described.

<How to make spray contents>
First, an aqueous dispersion of platinum-supported tungsten oxide particles used for preparing the spray contents was prepared.

[Preparation of aqueous dispersion of platinum-supported tungsten oxide particles]
The platinum-supported tungsten oxide particles prepared above and pure water were mixed so that the solid content concentration of the aqueous dispersion of the platinum-supported tungsten oxide particles was 20% by weight. The mixture was dispersed while irradiating with ultrasonic waves to prepare 1000 g of an aqueous dispersion of platinum-supported tungsten oxide particles.

Next, each spray content was prepared by the method shown below and filled in a trigger spray container.

[Preparation of spray contents (A-1)]
3-Glysidoxypropyltrimethoxysilane and pure water were mixed and hydrolyzed to prepare 4 g of an aqueous solution of 5% by weight of 3-glycidoxypropyltrimethoxysilane hydrolyzate. An aqueous solution of 3-glycidoxypropyltrimethoxysilane hydrolyzate and an aqueous dispersion of platinum-supported tungsten oxide particles prepared above using a magnetic stirrer and a stir bar (content of platinum-supported tungsten oxide particles: 20% by weight) 100 g was stirred to obtain a mixed solution. 64 g of pure water and 32 g of ethanol were added to the mixed solution to obtain a spray content (A-1) having a solid content concentration of 10% by weight. The binder content of the spray content (A-1) was 1% by weight based on the weight of the total solid content contained in the spray content (A-1).

[Preparation of spray contents (A-2)]
3-Glysidoxypropyltrimethoxysilane and pure water were mixed and hydrolyzed to prepare 21 g of an aqueous solution of 5% by weight of 3-glycidoxypropyltrimethoxysilane hydrolyzate. Using a magnetic stirrer and a stirrer, an aqueous solution of 3-glycidoxypropyltrimethoxysilane hydrolyzate and an aqueous dispersion of platinum-supported tungsten oxide particles prepared above (content of platinum-supported tungsten oxide particles: 20% by weight) 100 g was stirred to obtain a mixed solution. 58 g of pure water and 29 g of ethanol were added to the mixed solution to obtain a spray content (A-2) having a solid content concentration of 10% by weight. The binder content of the spray content (A-2) was 5% by weight based on the weight of the total solid content contained in the spray content (A-2).

[Preparation of spray contents (A-3)]
3-Glysidoxypropyltrimethoxysilane and pure water were mixed and hydrolyzed to prepare 44 g of an aqueous solution of 5% by weight of 3-glycidoxypropyltrimethoxysilane hydrolyzate. Using a magnetic stirrer and a stirrer, an aqueous solution of 3-glycidoxypropyltrimethoxysilane hydrolyzate and an aqueous dispersion of platinum-supported tungsten oxide particles prepared above (content of platinum-supported tungsten oxide particles: 20% by weight) 100 g was stirred to obtain a mixed solution. 52 g of pure water and 26 g of ethanol were added to the mixed solution to obtain a spray content (A-3) having a solid content concentration of 10% by weight. The binder content of the spray content (A-3) was 10% by weight based on the weight of the total solid content contained in the spray content (A-3).

[Preparation of spray contents (A-4)]
3-Glysidoxypropyltrimethoxysilane and pure water were mixed and hydrolyzed to prepare 100 g of an aqueous solution of 5% by weight of 3-glycidoxypropyltrimethoxysilane hydrolyzate. Using a magnetic stirrer and a stirrer, an aqueous solution of 3-glycidoxypropyltrimethoxysilane hydrolyzate and an aqueous dispersion of platinum-supported tungsten oxide particles prepared above (content of platinum-supported tungsten oxide particles: 20% by weight) 100 g was stirred to obtain a mixed solution. 32 g of pure water and 16 g of ethanol were added to the mixed solution to obtain a spray content (A-4) having a solid content concentration of 10% by weight. The binder content of the spray content (A-4) was 20% by weight based on the weight of the total solid content contained in the spray content (A-4).

[Preparation of spray contents (A-5)]
3-Glysidoxypropyltrimethoxysilane and pure water were mixed and hydrolyzed to prepare 133 g of an aqueous solution of 5% by weight of 3-glycidoxypropyltrimethoxysilane hydrolyzate. Using a magnetic stirrer and a stirrer, an aqueous solution of 3-glycidoxypropyltrimethoxysilane hydrolyzate and an aqueous dispersion of platinum-supported tungsten oxide particles prepared above (content of platinum-supported tungsten oxide particles: 20% by weight) 100 g was stirred to obtain a mixed solution. 22 g of pure water and 11 g of ethanol were added to the mixed solution to obtain a spray content (A-8) having a solid content concentration of 10% by weight. The binder content of the spray content (A-8) was 25% by weight based on the weight of the total solid content contained in the spray content (A-8).

[Preparation of spray contents (A-6)]
3-Aminopropyltrimethoxysilane and pure water were mixed and hydrolyzed to prepare 4 g of an aqueous solution of 5% by weight of 3-aminopropyltrimethoxysilane hydrolyzate. An aqueous solution of 3-aminopropyltrimethoxysilane hydrolyzate and an aqueous dispersion of platinum-supported tungsten oxide particles prepared above using a magnetic stirrer and a stir bar (content of platinum-supported tungsten oxide particles: 20 weight) %) 100 g was stirred to obtain a mixed solution. 64 g of pure water and 32 g of ethanol were added to the mixed solution to obtain a spray content (A-6) having a solid content concentration of 10% by weight. The binder content of the spray content (A-6) was 1% by weight based on the weight of the total solid content contained in the spray content (A-6).

[Preparation of spray contents (A-7)]
3-Aminopropyltrimethoxysilane and pure water were mixed and hydrolyzed to prepare 21 g of an aqueous solution of 5% by weight of 3-aminopropyltrimethoxysilane hydrolyzate. An aqueous solution of 3-aminopropyltrimethoxysilane hydrolyzate and an aqueous dispersion of platinum-supported tungsten oxide particles prepared above using a magnetic stirrer and a stir bar (content of platinum-supported tungsten oxide particles: 20 weight) %) 100 g was stirred to obtain a mixed solution. 58 g of pure water and 29 g of ethanol were added to the mixed solution to obtain a spray content (A-7) having a solid content concentration of 10% by weight. The binder content of the spray content (A-7) was 5% by weight based on the weight of the total solid content contained in the spray content (A-7).

[Preparation of spray contents (A-8)]
3-Aminopropyltrimethoxysilane and pure water were mixed and hydrolyzed to prepare 44 g of an aqueous solution of 5% by weight of 3-aminopropyltrimethoxysilane hydrolyzate. An aqueous solution of 3-aminopropyltrimethoxysilane hydrolyzate and an aqueous dispersion of platinum-supported tungsten oxide particles prepared above using a magnetic stirrer and a stir bar (content of platinum-supported tungsten oxide particles: 20 weight) %) 100 g was stirred to obtain a mixed solution. 52 g of pure water and 26 g of ethanol were added to the mixed solution to obtain a spray content (A-8) having a solid content concentration of 10% by weight. The binder content of the spray content (A-8) was 10% by weight based on the weight of the total solid content contained in the spray content (A-8).

[Preparation of spray contents (A-9)]
3-Aminopropyltrimethoxysilane and pure water were mixed and hydrolyzed to prepare 100 g of an aqueous solution of 5% by weight of 3-aminopropyltrimethoxysilane hydrolyzate. An aqueous solution of 3-aminopropyltrimethoxysilane hydrolyzate and an aqueous dispersion of platinum-supported tungsten oxide particles prepared above using a magnetic stirrer and a stir bar (content of platinum-supported tungsten oxide particles: 20 weight) %) 100 g was stirred to obtain a mixed solution. 32 g of pure water and 16 g of ethanol were added to the mixed solution to obtain a spray content (A-9) having a solid content concentration of 10% by weight. The binder content of the spray content (A-9) was 20% by weight based on the weight of the total solid content contained in the spray content (A-9).

[Preparation of spray contents (A-10)]
3-Aminopropyltrimethoxysilane and pure water were mixed and hydrolyzed to prepare 133 g of an aqueous solution of 5% by weight of 3-aminopropyltrimethoxysilane hydrolyzate. An aqueous solution of 3-aminopropyltrimethoxysilane hydrolyzate and an aqueous dispersion of platinum-supported tungsten oxide particles prepared above using a magnetic stirrer and a stir bar (content of platinum-supported tungsten oxide particles: 20 weight) %) 100 g was stirred to obtain a mixed solution. 22 g of pure water and 11 g of ethanol were added to the mixed solution to obtain a spray content (A-10) having a solid content concentration of 10% by weight. The binder content of the spray content (A-10) was 25% by weight based on the weight of the total solid content contained in the spray content (A-10).

[Preparation of spray contents (B-1)]
A spray having a solid content concentration of 10% by weight by adding 100 g of an aqueous dispersion of platinum-supported tungsten oxide particles (content of platinum-supported tungsten oxide particles: 20% by weight), 67 g of pure water and 33 g of ethanol prepared above. 200 g of the content (B-1) was obtained. The spray content (B-1) did not contain a binder.

<Spray evaluation method and evaluation results>
[Preparation of photocatalyst for evaluation]
The hand trigger spray was filled with the spray contents (A-1) to (A-10) and (B-1) and sprayed onto a substrate to prepare an evaluation photocatalyst body provided with a photocatalyst layer. Two types of substrates 1 and 2 shown below were used as substrates for producing the photocatalyst for evaluation.
Substrate 1: Borosilicate glass (length 50 mm x width 50 mm, thickness 1 mm)
Substrate 2: PEN film (manufactured by Teijin DuPont Film Co., Ltd., Q51, 50 mm x 50 mm, thickness 125 μm)

First, a treatment (UV ozone cleaning treatment) of irradiating the substrate with ultraviolet rays for 30 minutes was performed using an ultraviolet ozone irradiation device (manufactured by Technovision Co., Ltd., model: UV-312) equipped with a low-pressure mercury lamp. In this way, the surface of the base material was modified to be hydrophilic. Next, the spray was sprayed on the substrate multiple times until the thickness of the coating film (photocatalyst layer) after drying of the spray sprayed on the substrate became 3.0 g / m ² , and the room temperature was 40 ° C. Was dried for 24 hours. In this way, an evaluation photocatalyst having a photocatalyst layer on the substrate was obtained.

[Durability test]
The durability test was carried out by the method shown below. The evaluation photocatalyst after the water resistance test was dried at 40 ° C. for 24 hours. After drying, four mending tapes (tapes obtained by cutting "Model No. 810-3-12" manufactured by 3M Ltd. into a size of 50 mm in length and 12 mm in width) are applied to the surface of the photocatalyst layer of the photocatalyst for evaluation. I pasted them in parallel. Next, the four mending tapes were peeled off from the surface of the photocatalyst layer. The adhesive surfaces of the four peeled mending tapes were visually observed to confirm the presence or absence of the peeled photocatalyst layer.

The evaluation criteria for durability are shown below. Table 2 shows the evaluation results of the durability of the evaluation photocatalyst using each of the substrates 1 and 2. Further, the photocatalysts evaluated as Evaluation C and Evaluation D were evaluated as having poor durability (NG). In Table 2, "NG" is shown in the evaluation C and the evaluation D which are evaluated to have poor durability.
Evaluation A: No adhesion of the peeled photocatalyst layer is observed on any of the four mending tapes.
Evaluation B: Adhesion of the peeled photocatalyst layer is observed on one of the four mending tapes.
Evaluation C: Adhesion of the peeled photocatalyst layer is observed on 2 or 3 of the 4 mending tapes.
Evaluation D: Adhesion of the peeled photocatalyst layer is observed on 4 of the 4 mending tapes.

[Water resistance test]
The water resistance test was performed by the method shown below. Specifically, 100 mL of water was poured into a glass container having a capacity of 500 mL, and the photocatalyst for evaluation was immersed. With the evaluation photocatalyst immersed in water, the evaluation photocatalyst was allowed to stand at a water temperature of 20 ° C. for 1 hour. After taking out the evaluation photocatalyst from water, the remaining water was dried at 105 ° C., and the weight of the component (peeled component) peeled from the evaluation photocatalyst was measured. From the weight of the peeling component, the peeling rate (unit: weight%) was calculated based on the formula “peeling rate = 100 × weight of peeling component / weight of photocatalyst layer before water resistance test”. From the calculated peeling rate, the water resistance of the evaluation photocatalyst was evaluated according to the following criteria.

The evaluation criteria for water resistance are shown below. Table 2 shows the peeling rate of the evaluation photocatalyst using each of the substrates 1 or 2. Further, in Table 2, "NG" is shown for the peeling rate evaluated as having poor water resistance.
Good: The peeling rate is 0% or more and less than 10%.
Defective (NG): The peeling rate is 10% or more.

[Methylene blue decomposition test after water resistance test]
A methylene blue decomposition test (measurement of methylene blue fading rate), which is a confirmation test of photocatalytic activity, was performed by the method shown below. Using a micropipette, 20 μL of methylene blue reagent having a concentration of 100 μmol / L was added dropwise onto the photocatalyst layer of the evaluation photocatalyst substrate 1. The photocatalyst for evaluation after dropping was dried at room temperature. Then, a blue LED (peak wavelength 450 nm) lamp was used to irradiate the evaluation photocatalyst with 2,500 lux of light for 4 consecutive days. Then, the fading of methylene blue dropped on the photocatalyst layer of the photocatalyst for evaluation was visually determined. The fading of methylene blue is caused by the decomposition of methylene blue dropped on the photocatalyst layer of the evaluation photocatalyst by the photocatalyst activated by the light of the irradiated blue LED (peak wavelength 450 nm) lamp.
The evaluation criteria for the methylene blue decomposition test are shown below. Table 2 shows the measurement results of the fading rate of methylene blue of the evaluation photocatalyst using each substrate.
Good: No methylene blue coloring is seen.
Defective (NG): Methylene blue coloring remains.

[Deodorant test after water resistance test]
A deodorizing test (acetaldehyde gas decomposition measurement), which is a confirmation test of photocatalytic activity, was performed by the method shown below.
A 1 L gas bag was prepared, the photocatalyst substrate 2 for evaluation was put in, and then acetaldehyde gas was put in so as to have a concentration of 20 ppm. Next, using a blue LED (peak wavelength 450 nm) lamp, 2,500 lux of light was irradiated to the evaluation photocatalyst, and the change in acetaldehyde gas concentration 12 hours after the injection was measured by a detector tube.
Table 2 shows the deodorization test results of the evaluation photocatalyst using each substrate.
Good: Acetaldehyde gas residual rate is less than 50%.
Defective (NG): Acetaldehyde gas concentration is 50% or more.

The evaluation criteria for the comprehensive evaluation of the water resistance test, durability test, and methylene blue decomposition test are shown below. The results of the comprehensive evaluation are shown in Table 2.
Good: There is no defective (NG) evaluation in the water resistance test, durability test, and methylene blue decomposition test.
Deficiency: There is at least one defect (NG) rating in the water resistance test, durability test, and methylene blue decomposition test.

As shown in Table 1, the spray contents (A-1) to (A-10) contained at least photocatalytic particles, a binder, water and ethanol. The binder contained a water-soluble hydrolyzate of the silane coupling agent. Therefore, as shown in Table 2, the photocatalyst layer formed by the spray contents (A-1) to (A-10) was excellent in durability and durability. Further, the photocatalyst layer formed by the spray contents (A-1) to (A-10) maintained methylene blue decomposition activity and acetaldehyde gas decomposition activity equal to or higher than desired values.
As shown in Table 1, the spray content (B-1) did not contain a binder. Therefore, as shown in Table 2, the photocatalyst layer formed by the spray content (B-1) is inferior in terms of durability and water resistance, and the photocatalyst layer has been peeled off. Therefore, the substrate is used. The evaluated methylene blue decomposition activity and acetaldehyde gas decomposition activity were inferior.
From the above, it was shown that the spray content of the present invention is excellent in water resistance and durability while maintaining photocatalytic activity. Further, it was shown that according to the method for producing a photocatalyst of the present invention, a photocatalyst having excellent water resistance and durability can be produced while maintaining photocatalytic activity.

The spray of the present invention can be used for photocatalytically active products such as building materials, automobile interior materials, home appliances, and textile products.

Claims (8)

A photocatalytic spray containing at least photocatalytic particles, a binder and a solvent, wherein the binder contains a hydrolyzate of a water-soluble silane coupling agent, and the solvent contains ethanol and water. The photocatalyst spray according to claim 1, wherein the photocatalyst particles contain at least tungsten oxide. The photocatalytic spray according to claim 1 or 2, wherein the binder contains a hydrolyzate of a water-soluble silane coupling agent having an ethylene oxide structure. The photocatalytic spray according to claim 1 or 2, wherein the binder contains a hydrolyzate of a water-soluble silane coupling agent having an amine structure. The invention according to any one of claims 1 to 4, wherein the content of the hydrolyzate is 0.5% by weight or more and 20% by weight or less with respect to the weight of the total solid content contained in the photocatalytic spray. Photocatalytic spray. The photocatalyst spray according to any one of claims 1 to 5, wherein the content of the photocatalyst particles is 75% by weight or more and 99% by weight or less with respect to the weight of the total solid content contained in the photocatalyst spray. .. The steps 1 to 6 include the step of mixing the binder containing the hydrolyzate of the water-soluble silane coupling agent, the photocatalytic particles, and a solvent containing at least ethanol and water to obtain the photocatalytic spray. The method for producing a photocatalytic spray according to any one of the above. By spraying the photocatalyst spray according to any one of claims 1 to 6 onto a substrate and drying the components, the photocatalyst particles and the photocatalyst particles are interposed via the binder containing the hydrolyzate of the silane coupling agent. A method for producing a photocatalyst, which comprises a step of binding to the base material.