JP2021175697A - Titanium oxide particle, dispersion thereof, photocatalyst thin film, member having photocatalyst thin film on its surface, and method for producing titanium oxide particle dispersion - Google Patents

Abstract

To provide a titanium oxide particle having improved photocatalytic activity, in particular visible light activity, a dispersion thereof, a photocatalyst thin film formed with the dispersion, a member having a photocatalyst thin film on its surface and a method for producing a titanium oxide particle dispersion.SOLUTION: A titanium oxide particle has (1) a tin component and a transition metal component for improving visible light activity dissolved in a solid state and (2) an iron component and a silicon component attached to the surface. There is also provided a titanium oxide particle dispersion having the titanium oxide particles dispersed in an aqueous dispersion medium.SELECTED DRAWING: None

Description

The present invention relates to titanium oxide particles, a dispersion liquid thereof, a photocatalyst thin film formed by using the dispersion liquid, a member having a photocatalyst thin film on the surface, and a method for producing the titanium oxide particle dispersion liquid. The present invention relates to visible light responsive photocatalytic titanium oxide particles and the like, which can easily produce a highly transparent photocatalytic thin film that exhibits photocatalytic activity only at 400 to 800 nm).

Photocatalysts are often used for cleaning the surface of a base material, deodorizing, antibacterial and the like. The photocatalytic reaction is a reaction caused by excited electrons and holes generated by absorption of light by a photocatalyst. Decomposition of organic matter by photocatalyst is considered to occur mainly by the following mechanisms [1] and [2].
[1] The generated excited electrons and holes undergo a redox reaction with oxygen and water adsorbed on the surface of the photocatalyst, and the active species generated by the redox reaction decompose organic substances.
[2] The generated holes directly oxidize and decompose organic substances adsorbed on the surface of the photocatalyst.

Recently, the application of photocatalytic action as described above is not limited to outdoor use where ultraviolet rays can be used, but also indoors illuminated by a light source such as a fluorescent lamp in which light in the visible region (wavelength 400 to 800 nm) occupies most of the light. Consideration is being made to make it available in space. For example, a tungsten oxide photocatalyst (Japanese Patent Laid-Open No. 2009-148700: Patent Document 1) was developed as a visible light responsive photocatalyst. However, since tungsten is a rare element, a photocatalyst using titanium, which is a general-purpose element, has been developed. Improvement of visible light activity is desired.

As a method for improving the visible light activity of a photocatalyst using titanium oxide, a method of supporting iron or copper on the surface of titanium oxide fine particles or metal-doped titanium oxide fine particles (for example, Japanese Patent Application Laid-Open No. 2012-120632: Patent Document). 2. JP-A-2010-104913: Patent Document 3, JP-A-2011-240247: Patent Document 4, JP-A-7-303835: Patent Document 5), solidifying tin and transition metals that enhance visible light activity. A method in which molten (doped) titanium oxide fine particles and copper oxide fine particles in which copper is solid-dissolved are prepared and then mixed and used (International Publication No. 2014/045861: Patent Document 6) to enhance the responsiveness to tin and visible light. A method is known in which titanium oxide fine particles in which a transition metal is solid-dissolved and titanium oxide fine particles in which an iron group element is solid-dissolved are prepared and then mixed and used (International Publication No. 2016/152487: Patent Document 7). ..

Visible light-responsive photocatalytic titanium oxide obtained by preparing tin oxide in Patent Document 7, fine particles of titanium oxide in which a transition metal that enhances visible light activity is solid-dissolved, and fine particles of titanium oxide in which iron group elements are solid-dissolved, and then mixing them. When a photocatalyst film formed by using a fine particle dispersion is used, high decomposition activity can be obtained under the condition of only light in the visible region. Also, when a photocatalyst film formed using a titanium oxide fine particle dispersion liquid in which an iron component is adsorbed (= supported) on the surface of titanium oxide fine particles in which tin and a transition metal that enhances visible light activity is solid-dissolved is used. It has been shown that acetaldehyde gas can be decomposed under the condition of only light in the visible light region, but the iron component impairs the quality of the photocatalytic film obtained by the aggregation and precipitation of titanium oxide fine particles due to the iron component. The amount of photocatalyst was limited and the resulting photocatalytic activity was low.

As mentioned above, although studies to increase the photocatalytic activity have been actively conducted, it is important to decompose and remove harmful substances as quickly as possible in the actual environment, so that the photocatalytic activity can be further improved. It has been demanded.

JP-A-2009-148700 Japanese Unexamined Patent Publication No. 2012-120632 JP-A-2010-104913 Japanese Unexamined Patent Publication No. 2011-240247 Japanese Unexamined Patent Publication No. 7-303835 International Publication No. 2014/045861 International Publication No. 2016/152487

Therefore, in the present invention, titanium oxide particles capable of obtaining higher photocatalytic activity, particularly visible light activity, a dispersion liquid thereof, a photocatalytic thin film formed by using the dispersion liquid, a member having a photocatalytic thin film on the surface, and titanium oxide It is an object of the present invention to provide a method for producing a particle dispersion liquid.

In order to achieve the above object, the present inventors have studied in detail the metal elements to be dissolved in the titanium oxide particles and their combinations, the metal elements to be added to the titanium oxide particles and their combinations, their amount ratios, and the like. Photocatalytic activity of titanium oxide particles in which the iron component and silicon component obtained by mixing an iron component and a silicon component in (particularly titanium oxide particles in which a specific metal is solid-dissolved) are attached to the surface, particularly visible light. The present invention has been completed by finding that the activity is dramatically improved.

Therefore, the present invention provides the following titanium oxide particles, a dispersion liquid thereof, a photocatalyst thin film formed by using the dispersion liquid, a member having a photocatalyst thin film on the surface, and a method for producing the titanium oxide particle dispersion liquid. ..
[1]
1) The tin component and the transition metal component that enhances visible light activity are solid-dissolved.
2) Titanium oxide particles to which iron and silicon components are attached to the surface.
[2]
The titanium oxide particle according to [1], wherein the transition metal component dissolved in the titanium oxide particle is at least one selected from vanadium, chromium, manganese, niobium, molybdenum, rhodium, tungsten and cerium.
[3]
The titanium oxide particles according to [2], wherein the transition metal component dissolved in the titanium oxide particles is at least one selected from molybdenum, tungsten, and vanadium components.
[4]
The titanium oxide particles according to any one of [1] to [3], wherein the content of the tin component solidly dissolved in the titanium oxide particles is 1 to 1,000 in terms of molar ratio (Ti / Sn) with titanium. ..
[5]
The molar ratio (Ti / Fe) of the iron component to titanium is 10 to 10,000, and the molar ratio (Ti / Si) of the silicon component to titanium is 1 to 10,000 [1] to [4]. The titanium oxide particles according to any one of the above items.
[6]
[3] The amount of each of the molybdenum, tungsten, and vanadium components dissolved in the titanium oxide particles is 1 to 10,000 in terms of molar ratio with titanium (Ti / Mo or Ti / W or Ti / V). Titanium oxide particles.
[7]
The titanium oxide particle according to any one of [1] to [6], wherein at least one metal component selected from molybdenum, tungsten and vanadium components is attached to the surface thereof.
[8]
A titanium oxide particle dispersion liquid in which the titanium oxide particles according to any one of [1] to [7] are dispersed in an aqueous dispersion medium.
[9]
Further, the titanium oxide particle dispersion liquid according to [8], which contains a binder.
[10]
The titanium oxide particle dispersion liquid according to [9], wherein the binder is a silicon compound-based binder.
[11]
The photocatalytic thin film containing the titanium oxide particles according to any one of [1] to [7].
[12]
The photocatalytic thin film according to [11], which further contains a binder.
[13]
A member in which the photocatalytic thin film of [11] or [12] is formed on the surface of a base material.
[14]
A method for producing a titanium oxide particle dispersion liquid, which comprises the following steps (1) to (4).
(1) Step of producing a peroxotitanic acid solution containing a tin component and a transition metal component from a raw material titanium compound, a tin compound, a transition metal compound, a basic substance, hydrogen peroxide and an aqueous dispersion medium (2) The above (1) A step of heating a peroxotitanic acid solution containing a tin component and a transition metal component produced in the step at 80 to 250 ° C. under pressure control to obtain a titanium oxide particle dispersion containing a tin component and a transition metal component (3) Iron compound , A step of producing a solution or dispersion of an iron component and a silicon component from a silicon compound and an aqueous dispersion medium (4) A titanium oxide particle dispersion produced in the above step (2) and a step (3). Step of mixing solution or dispersion of iron compound and silicon compound to obtain dispersion

The titanium oxide particles of the present invention have higher photocatalytic activity than conventional ones, particularly high photocatalytic activity even with visible light (wavelength 400 to 800 nm) alone. Further, a highly transparent photocatalyst thin film can be easily produced from the dispersion liquid of the titanium oxide particles. Therefore, the titanium oxide particles of the present invention are useful for members used in an indoor space illuminated by a light source such as a fluorescent lamp or a white LED, which is dominated by visible light.

Hereinafter, the present invention will be described in detail.
<Titanium oxide particle dispersion>
The titanium oxide particle dispersion of the present invention contains 1) a tin component and a transition metal that enhances visible light activity as a solid solution, and 2) an iron component and a silicon component in an aqueous dispersion medium. Is. The iron component and the silicon component contained in the titanium oxide particle dispersion liquid are attached to the surface of the titanium oxide particles, but the iron component and the silicon component may be liberated in the titanium oxide particle dispersion liquid.

Water is preferably used as the aqueous dispersion medium, but a mixed solvent of water and a hydrophilic organic solvent mixed with water at an arbitrary ratio may be used. As the water, for example, purified water such as filtered water, deionized water, distilled water, and pure water is preferable. Examples of the hydrophilic organic solvent include alcohols such as methanol, ethanol and isopropanol, glycols such as ethylene glycol, glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether and propylene glycol-n-propyl ether. Kind is preferred. When a mixed solvent is used, the proportion of the hydrophilic organic solvent in the mixed solvent is more than 0% by mass, preferably 50% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass or less. Is.

As the titanium oxide particles, titanium oxide used as a photocatalyst is a solid solution of a tin component and a transition metal component that enhances visible light activity, and the titanium oxide particle dispersion of the present invention "contains an iron component and a silicon component". "To do" means that the dispersion liquid contains the iron component and the silicon component.

There are usually three known crystal phases of titanium oxide particles, rutile type, anatase type, and brookite type, but the titanium oxide particles of the present invention are preferably rutile type or anatase type, and in particular, It is preferably rutile type. The term "mainly" as used herein means that the titanium oxide particles of the crystal phase are contained in an amount of 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass, based on the total titanium oxide particles. As mentioned above, it may be 100% by mass.

Here, in the present specification, a solid solution is a phase in which an atom at a lattice point of a certain crystal phase is replaced with another atom or another atom is inserted in a lattice gap, that is, another crystal phase. It means that it has a mixed phase in which the substance of the above is considered to be dissolved, and it means that it is a uniform phase as a crystal phase. A solid solution in which a solvent atom at a lattice point is replaced with a solute atom is referred to as a substituted solid solution, and a solid solution in which a solute atom is contained in a lattice gap is referred to as an intrusive solid solution. In the present specification, both of them are referred to.

The titanium oxide particles of the present invention are characterized in that they form a solid solution with tin atoms and transition metal atoms that enhance visible light responsiveness. The solid solution may be a substitution type or an invasion type. The titanium oxide substitution type solid solution is formed by substituting the titanium sites of the titanium oxide crystal with various metal atoms, and the titanium oxide invasion type solid solution contains various metal atoms in the lattice gaps of the titanium oxide crystal. It is what is formed. When various metal atoms are dissolved in titanium oxide, when the crystal phase is measured by X-ray diffraction or the like, only the peak of the crystal phase of titanium oxide is observed, and the peak of the compound derived from the added various metal atoms is not observed. ..

The method for solidifying a dissimilar metal into a metal oxide crystal is not particularly limited, but is a gas phase method (CVD method, PVD method, etc.), a liquid phase method (hydrothermal method, sol-gel method, etc.), or solid. The phase method (high temperature firing method, etc.) can be mentioned.

The tin component that dissolves in the titanium oxide particles is for enhancing the visible light responsiveness of the photocatalyst thin film, but it may be derived from a tin compound, for example, tin metal alone (Sn), oxidation. Substances (SnO, SnO ₂ ), hydroxides, chlorides (SnCl ₂ , SnCl ₄ ), nitrates (Sn (NO ₃ ) ₂ ), sulfates (SnSO ₄ ), halogens (Br, I), oxoate (Na ₂ SnO ₃ , K ₂ SnO ₃ ), complex compounds and the like can be mentioned, and one or a combination of two or more of these may be used. Among them, oxides (SnO, SnO ₂ ), chlorides (SnCl ₂ , SnCl ₄ ), sulfates (SnSO ₄ ), and oxoacids (Na ₂ SnO ₃ , K ₂ SnO ₃ ) are preferably used.

The amount of the tin component dissolved in the titanium oxide particles is 1 to 1,000, preferably 5 to 500, and more preferably 5 to 100 in terms of molar ratio (Ti / Sn) with titanium. This is because if the molar ratio is less than 1, the titanium oxide content may decrease and the photocatalytic effect may not be sufficiently exhibited, and if it exceeds 1,000, the visible light responsiveness may become insufficient. be.

The transition metal that dissolves in the titanium oxide particles is for enhancing the visible light responsiveness of the photocatalyst thin film, and is one or more elements selected from Group 3 to Group 11 of the periodic table. Yes, it can be selected from vanadium, chromium, manganese, niobium, molybdenum, rhodium, tungsten, cerium and the like, of which molybdenum, tungsten and vanadium are preferable.

The transition metal component dissolved in the titanium oxide particles may be derived from the transition metal compound, and may be a metal, an oxide, a hydroxide, a chloride, a nitrate, a sulfate, or a halogen (Br, I). Examples thereof include compounds, oxolates, and various complex compounds, and one or more of these are used.

The amount of the transition metal component dissolved in the titanium oxide particles can be appropriately selected depending on the type of the transition metal component, but the molar ratio (Ti / transition metal) with titanium may be 1 to 10,000. preferable.

When molybdenum is selected as the transition metal component to be dissolved in titanium oxide particles, the molybdenum component may be derived from a molybdenum compound. For example, molybdenum metal alone (Mo), oxide (MoO ₂ , MoO) ₃ ), hydroxides, chlorides (MoCl ₃ , MoCl ₅ ), nitrates, sulfates, halogen (Br, I) compounds, molybdic acid and oxoate (H ₂ MoO ₄ , Na ₂ MoO ₄ , K ₂ MoO) ₄ ), complex compounds and the like can be mentioned, and one or a combination of two or more of these may be used. Among them, oxides (MoO ₂ , MoO ₃ ), chlorides (MoCl ₃ , MoCl ₅ ), and oxoacid salts (H ₂ MoO ₄ , Na ₂ MoO ₄ , K ₂ MoO ₄ ) are preferably used.

The amount of the molybdenum component dissolved in the titanium oxide particles is 1 to 10,000, preferably 5 to 5,000, and more preferably 20 to 1,000 in terms of molar ratio (Ti / Mo) with titanium. This is because if the molar ratio is less than 1, the titanium oxide content may decrease and the photocatalytic effect may not be sufficiently exhibited, and if it exceeds 10,000, the visible light responsiveness may become insufficient. be.

When tungsten is selected as the transition metal component that is dissolved in the titanium oxide particles, the tungsten component may be derived from a tungsten compound, for example, tungsten metal alone (W), oxide (WO ₃ ), or the like. Hydroxides, chlorides (WCl ₄ , WCl ₆ ), nitrates, sulfates, halogen (Br, I) compounds, tungstic acid and oxoate (H ₂ WO ₄ , Na ₂ WO ₄ , K ₂ WO ₄ ), Examples thereof include complex compounds, and one or a combination of two or more of these may be used. Among them, oxides (WO ₃ ), chlorides (WCl ₄ , WCl ₆ ), and oxoacid salts (Na ₂ WO ₄ , K ₂ WO ₄ ) are preferably used.

The amount of the tungsten component dissolved in the titanium oxide particles is 1 to 10,000, preferably 5 to 5,000, and more preferably 20 to 2,000 in terms of molar ratio (Ti / W) with titanium. This is because if the molar ratio is less than 1, the titanium oxide content may decrease and the photocatalytic effect may not be sufficiently exhibited, and if it exceeds 10,000, the visible light responsiveness may become insufficient. be.

When vanadium is selected as the transition metal component to be dissolved in titanium oxide particles, the vanadium component may be derived from a vanadium compound, for example, vanadium metal alone (V), oxide (VO, V _2). O ₃ , VO ₂ , V ₂ O ₅ ), hydroxide, chloride (VCl ₅ ), oxychloride (VOCl ₃ ), nitrate, sulfate, oxysulfate (VOSO ₄ ), halogen (Br, I) products, oxo acid salt _{(Na 3 VO 4, K 3} VO 4, KVO 3), complex compounds, and the like, may be obtained by using a combination of one or more of them. Among them, oxides (V ₂ O ₃ , V ₂ O ₅ ), chlorides (VCl ₅ ), oxychlorides (VOCl ₃ ), oxysulfates (VOSO ₄ ), oxoacids (Na ₃ VO ₄ , K) It is preferable to use ₃ VO ₄ , KVO _3).

The amount of the vanadium component dissolved in the titanium oxide particles is 1 to 10,000, preferably 10 to 10,000, and more preferably 100 to 10,000 in terms of molar ratio (Ti / V) with titanium. This is because if the molar ratio is less than 1, the titanium oxide content may decrease and the photocatalytic effect may not be sufficiently exhibited, and if it exceeds 10,000, the visible light responsiveness may become insufficient. be.

A plurality of transition metal components to be dissolved in titanium oxide particles can be selected from molybdenum, tungsten, and vanadium, and the amount of each component at that time can be selected from the above range. However, the molar ratio [Ti / (Mo + W + V)] of the total amount of each component to titanium is 1 or more and less than 10,000.

The titanium oxide particles may be used alone or in combination of two or more. When two or more kinds having different visible light responsiveness are combined, the effect of increasing visible light activity may be obtained.

The iron component and silicon component contained in the titanium oxide particle dispersion and adhering to the surface of the titanium oxide particles enhance the visible light responsiveness of the photocatalytic thin film, whereas the titanium oxide particle dispersion contains the iron component and silicon. In addition to the components, at least one metal component selected from molybdenum, tungsten, and vanadium components, which are also transition metal components dissolved in titanium oxide particles, may be contained as a component that further enhances the visible light responsiveness.

The iron component contained in the titanium oxide particle dispersion is for enhancing the visible light responsiveness of the photocatalyst thin film, but it may be derived from an iron compound, for example, iron metal alone (Fe), oxidation. Substances (Fe ₂ O ₃ , Fe ₃ O ₄ ), hydroxides (Fe (OH) ₂ , Fe (OH) ₃ ), oxyhydroxide (FeO (OH)), chlorides (FeCl ₂ , FeCl ₃ ) , Nitrate (Fe (NO) ₃ ), Sulfate (FeSO ₄ , Fe ₂ (SO ₄ ) ₃ ), Halogen (Br, I) compounds, complex compounds, etc., and one or more of these may be combined. May be used.

The content of the iron component contained in the titanium oxide particle dispersion is 10 to 10,000, preferably 20 to 5,000, and more preferably 50 to 2,000 in terms of molar ratio (Ti / Fe) with titanium. .. This is because if the molar ratio is less than 10, the quality of the photocatalytic thin film obtained by agglomeration and precipitation of titanium oxide may deteriorate and the photocatalytic effect may not be sufficiently exhibited, and if it exceeds 10,000, the visible light responsiveness may be reduced. This is because it may be insufficient.

The silicon component contained in the titanium oxide particle dispersion liquid suppresses the aggregation and precipitation of titanium oxide and the iron component when the iron component is added, thereby preventing the deterioration of the quality of the photocatalyst thin film and suppressing the deterioration of the photocatalyst effect. , It may be derived from a silicon compound, for example, silicon metal alone (Si), oxide (SiO, SiO ₂ ), alkoxide (Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Examples thereof include Si (OCH (CH ₃ ) ₂ ) ₄ ), silicate (sodium salt, potassium salt) and active silicic acid obtained by removing at least a part of ions such as sodium and potassium from the silicate. You may use one kind or a combination of two or more kinds of. Among them, it is preferable to use silicate (sodium silicate) and active silicic acid, particularly active silicic acid.

The content of the silicon component contained in the titanium oxide particle dispersion is 1 to 10,000, preferably 2 to 5,000, and more preferably 5 to 2,000 in terms of molar ratio (Ti / Si) with titanium. .. This is because when the molar ratio is less than 1, the content ratio of titanium oxide decreases and the photocatalytic effect may not be sufficiently exhibited, and when it exceeds 10,000, the effect of suppressing the aggregation and precipitation of titanium oxide becomes insufficient. Because there are times.

When a transition metal component (molybdenum, tungsten, vanadium) is further added to the titanium oxide particle dispersion in order to further enhance the visible light responsiveness of the photocatalyst thin film, the content of the transition metal component contained in the titanium oxide particle dispersion is It can be appropriately selected depending on the type of transition metal component, but the molar ratio (Ti / transition metal) with titanium is preferably 10 to 10,000.

When molybdenum is selected as the transition metal component contained in the titanium oxide particle dispersion, the molybdenum component may be derived from the same molybdenum compound as that used for solid dissolution in the titanium oxide particles.

The content of the molybdenum component contained in the titanium oxide particle dispersion is 10 to 10,000, preferably 20 to 5,000, and more preferably 30 to 3,000 in terms of molar ratio (Ti / Mo) with titanium. .. This is because if the molar ratio is less than 10, the titanium oxide content may decrease and the photocatalytic effect may not be sufficiently exhibited, and if it exceeds 10,000, the visible light responsiveness may become insufficient. be.

When tungsten is selected as the transition metal component contained in the titanium oxide particle dispersion, the tungsten component may be derived from a tungsten compound similar to that used for solid dissolution in titanium oxide particles.

The content of the tungsten component contained in the titanium oxide particle dispersion is 10 to 10,000, preferably 20 to 5,000, and more preferably 30 to 3,000 in terms of molar ratio (Ti / W) with titanium. .. This is because if the molar ratio is less than 10, the titanium oxide content may decrease and the photocatalytic effect may not be sufficiently exhibited, and if it exceeds 10,000, the visible light responsiveness may become insufficient. be.

When vanadium is selected as the transition metal component contained in the titanium oxide particle dispersion, the vanadium component may be derived from the same vanadium compound as that used for solid dissolution in the titanium oxide particles.

The content of the vanadium component contained in the titanium oxide particle dispersion is 10 to 10,000, preferably 20 to 5,000, and more preferably 30 to 3,000 in terms of molar ratio (Ti / V) with titanium. .. This is because if the molar ratio is less than 10, the titanium oxide content may decrease and the photocatalytic effect may not be sufficiently exhibited, and if it exceeds 10,000, the visible light responsiveness may become insufficient. be.

As the transition metal component contained in the titanium oxide particle dispersion, a plurality of molybdenum, tungsten, and vanadium can be selected. The amount of each component at that time can be selected from the above range. However, the molar ratio [Ti / (Mo + W + V)] of the total amount of each component to titanium is 10 or more and less than 10,000.

The titanium oxide particles in the titanium oxide particle dispersion containing the iron component and the silicon component have a 50% cumulative distribution diameter (hereinafter referred to as _{D 50) based on the volume measured by a dynamic light scattering method using a laser beam.} However, it is preferably 3 to 50 nm, more preferably 3 to 30 nm, and even more preferably 3 to 20 nm. This is because if D ₅₀ is less than 3 nm, the photocatalytic activity may be insufficient, and if it exceeds 50 nm, the dispersion may become opaque.

The volume-based 90% cumulative distribution diameter (hereinafter, _{may be referred to as D 90} ) is preferably 5 to 100 nm, and more preferably 5 to 80 nm. This is because if D ₉₀ is less than 5 nm, the photocatalytic activity may be insufficient, and if it exceeds 100 nm, the dispersion liquid may become opaque.
It is preferable that the titanium oxide particles of the present invention have D ₅₀ and D ₉₀ in the above-mentioned range because they have high photocatalytic activity and provide a highly transparent dispersion liquid.
_{Examples of devices for measuring D 50} and D ₉₀ of titanium oxide particles in the titanium oxide particle dispersion include ELSZ-2000ZS (manufactured by Otsuka Electronics Co., Ltd.) and Nanotrack UPA-EX150 (Nikkiso Co., Ltd.). , LA-910 (manufactured by HORIBA, Ltd.) and the like can be used.

The concentration of titanium oxide particles in the titanium oxide particle dispersion is preferably 0.01 to 20% by mass, particularly preferably 0.5 to 10% by mass, in terms of ease of producing a photocatalyst thin film having a required thickness. ..

Further, a binder may be added to the titanium oxide particle dispersion liquid for the purpose of facilitating application of the dispersion liquid to the surfaces of various members described later and facilitating adhesion of the particles. Examples of the binder include a metal compound-based binder containing silicon, aluminum, titanium, zirconium and the like, an organic resin-based binder containing a fluorine-based resin, an acrylic resin, a urethane-based resin and the like.

The mass ratio of the binder to titanium oxide [titanium oxide / binder] should be added in the range of 99 to 0.01, more preferably 9 to 0.1, and even more preferably 2.5 to 0.4. Is preferable. This is because if the mass ratio exceeds 99, the adhesion of titanium oxide particles to the surfaces of various members is insufficient, and if it is less than 0.01, the visible light activity may be insufficient.

Above all, in order to obtain an excellent photocatalytic thin film having high photocatalytic activity and transparency, a silicon compound-based binder has a mass ratio (titanium oxide / silicon compound-based binder) of 99 to 0.01, more preferably 9 to 0.1. , More preferably, it is preferably added in the range of 2.5 to 0.4 for use. Here, the silicon compound-based binder is a colloidal dispersion, a solution, or an emulsion of a silicon compound containing a solid or liquid silicon compound in an aqueous dispersion medium, and specifically, colloidal silica. (Preferable particle size 1 to 150 nm); silicate solution such as silicate; silane, siloxane hydrolyzate emulsion; silicone resin emulsion; silicone resin such as silicone-acrylic resin copolymer, silicone-urethane resin copolymer and others Emulsion of a copolymer with the resin of the above can be mentioned.

<Manufacturing method of titanium oxide particle dispersion liquid>
In the method for producing a titanium oxide particle dispersion liquid of the present invention, a titanium oxide particle dispersion liquid and a solution or dispersion of an iron component and a silicon component are produced, respectively, and a titanium oxide particle dispersion liquid and a solution or dispersion of an iron component and a silicon component are produced. It is prepared by mixing with a liquid.

Specifically, the following steps (1) to (4) are performed as a method for producing a titanium oxide particle dispersion liquid containing a tin component and a transition metal component that enhances visible light responsiveness and contains an iron component and a silicon component. Examples of the manufacturing method to have.
(1) Step of producing a peroxotitanic acid solution containing a tin component and a transition metal component from a raw material titanium compound, a tin compound, a transition metal compound, a basic substance, hydrogen peroxide and an aqueous dispersion medium (2) The above (1) A step of heating a peroxotitanic acid solution containing a tin component and a transition metal component produced in the step at 80 to 250 ° C. under pressure control to obtain a titanium oxide particle dispersion containing a tin component and a transition metal component (3) Iron compound , A step of producing a solution or dispersion of an iron component and a silicon component from a silicon compound and an aqueous dispersion medium (4) A titanium oxide particle dispersion produced in the above step (2) and a step (3). Step of mixing a solution or dispersion of an iron compound and a silicon compound to obtain a dispersion

Steps (1) and (2) are steps to obtain a titanium oxide particle dispersion liquid in which a tin component and a transition metal component that enhances visible light responsiveness are solid-dissolved, and step (3) is a solution or dispersion of an iron component and a silicon component. It is a step of obtaining a liquid, and the step (4) finally dissolves the tin component and the transition metal component that enhances the visible light responsiveness, and contains titanium oxide particles in which the iron component and the silicon component are attached to the surface. This is a step of obtaining a dispersion liquid.
As described above, it is preferable to use at least one of the molybdenum compound, the tungsten compound and the vanadium compound as the transition metal compound used in the step (1), and therefore each step will be described in detail below on that premise. do.

・ Process (1):
In the step (1), a peroxotitanic acid solution containing a tin component and a transition metal component is produced by reacting a raw material titanium compound, a tin compound, a transition metal compound, a basic substance and hydrogen peroxide in an aqueous dispersion medium.

The reaction method may be any of the following methods i) to iii).

i) A tin compound and a transition metal compound are added to and dissolved in the raw material titanium compound and the basic substance in the aqueous dispersion medium to obtain titanium hydroxide containing the tin component and the transition metal component, except for the metal ions contained therein. A method of removing impurity ions from the above and adding hydrogen peroxide to obtain peroxotitanic acid containing a tin component and a transition metal component.

ii) A basic substance is added to the raw material titanium compound in the aqueous dispersion medium to obtain titanium hydroxide, and after removing impurity ions other than the contained metal ions, a tin compound and a transition metal compound are added, and then hydrogen peroxide is added. Method of adding peroxotitanic acid containing tin component and transition metal component

iii) Add a basic substance to the raw material titanium compound in the aqueous dispersion medium to obtain titanium hydroxide, remove impurity ions other than the contained metal ions, add hydrogen peroxide to obtain peroxotitanic acid, and then tin compound. And a method of adding a transition metal compound to obtain peroxotitanic acid containing a tin component and a transition metal component.

In the first stage of the method i), "the raw material titanium compound and the basic substance in the aqueous dispersion medium" were replaced with "the aqueous dispersion medium in which the raw material titanium compound was dispersed" and "the aqueous dispersion medium in which the basic substance was dispersed". , And each compound is dissolved in one or both of the two solutions according to the solubility of each compound of the tin compound and the transition metal compound in the two solutions. After that, both may be mixed.

After obtaining the tin component and transition metal component-containing peroxotitanic acid in this way, it is possible to obtain titanium oxide particles in which the various metals are solid-dissolved in titanium oxide by subjecting the peroxotitanic acid to the hydrothermal reaction in the step (2) described later. can.

Here, as the raw material titanium compound, for example, inorganic acid salts such as titanium chloride, nitrate and sulfate, organic acid salts such as formic acid, citric acid, oxalic acid, lactic acid and glycolic acid, and alkalis are added to these aqueous solutions. Examples thereof include titanium hydroxide precipitated by hydrolysis, and one or a combination of two or more of these may be used. Among them, it is preferable to use titanium chloride (TiCl ₃ , TiCl _4).

As the tin compound, the transition metal compound, and the aqueous dispersion medium, the above-mentioned ones are used so as to have the above-mentioned formulations. The concentration of the raw material titanium compound aqueous solution formed from the raw material titanium compound and the aqueous dispersion medium is preferably 60% by mass or less, particularly preferably 30% by mass or less. The lower limit of the concentration is appropriately selected, but it is usually preferably 1% by mass or more.

The basic substance is for smoothly converting the raw material titanium compound into titanium hydroxide, for example, hydroxide of an alkali metal such as sodium hydroxide or potassium hydroxide or an alkaline earth metal, ammonia, alkanolamine, alkyl. Examples thereof include amine compounds such as amines. Among them, ammonia is particularly preferable, and the raw material titanium compound aqueous solution is added in an amount such that the pH is 7 or more, particularly pH 7 to 10. The basic substance may be used together with the aqueous dispersion medium as an aqueous solution having an appropriate concentration.

Hydrogen peroxide is for converting the raw material titanium compound or titanium hydroxide into peroxotitanium, that is, a titanium oxide compound containing a Ti—O—O—Ti bond, and is usually used in the form of a hydrogen peroxide solution. Will be done. The amount of hydrogen peroxide added is preferably 1.5 to 20 times the molar amount of the total amount of substances of Ti, transition metal and Sn. Further, in the reaction of adding hydrogen peroxide to convert the raw material titanium compound or titanium hydroxide into peroxotitanic acid, the reaction temperature is preferably 5 to 80 ° C., and the reaction time is 30 minutes to 24 hours. preferable.

The peroxotitanic acid solution containing the tin component and the transition metal component thus obtained may contain an alkaline substance or an acidic substance for pH adjustment and the like. Examples of the alkaline substance here include ammonia, sodium hydroxide, calcium hydroxide, alkylamine and the like, and examples of the acidic substance include sulfuric acid, nitric acid, hydrochloric acid, carbonic acid, phosphoric acid, hydrogen peroxide and the like. Examples thereof include inorganic acids and organic acids such as formic acid, citric acid, slaked acid, lactic acid, and glycolic acid. In this case, the pH of the obtained peroxotitanic acid solution containing the tin component and the transition metal component is preferably 1 to 9, particularly 4 to 7, from the viewpoint of handling safety.

・ Process (2):
In the step (2), the tin component and transition metal component-containing peroxotitanic acid solution obtained in the above step (1) is subjected to 0.01 at a temperature of 80 to 250 ° C., preferably 100 to 250 ° C. under pressure control. Subject to hydrothermal reaction for ~ 24 hours. The reaction temperature is appropriately 80 to 250 ° C. from the viewpoint of reaction efficiency and controllability of the reaction. As a result, the tin component and the transition metal component-containing peroxotitanic acid are oxidized by dissolving the tin component and the transition metal component. It is converted into titanium particles. Here, under pressure control means that when the reaction temperature exceeds the boiling point of the dispersion medium, the reaction temperature is maintained by appropriately applying pressure so that the reaction temperature can be maintained. This includes the case of controlling at atmospheric pressure when the temperature is below the boiling point. The pressure used here is usually about 0.12 to 4.5 MPa, preferably about 0.15 to 4.5 MPa, and more preferably about 0.20 to 4.5 MPa. The reaction time is preferably 1 minute to 24 hours. By this step (2), a titanium oxide particle dispersion liquid in which a tin component and a transition metal component are solid-solved is obtained.
The pH of the titanium oxide particle dispersion liquid in which the tin component and the transition metal component obtained in this step (2) are solid-solved is preferably 8 to 14, and more preferably 10 to 14. The titanium oxide particle dispersion in which the tin component and the transition metal component obtained in this step (2) are dissolved may contain an alkaline substance or an acidic substance for pH adjustment or the like so as to have the above-mentioned pH. , The alkaline substance, the acidic substance and the method of adjusting the pH are the same as those of the peroxotitanic acid solution obtained in the above-mentioned step (1).

The particle size of the titanium oxide particles obtained here is preferably in the range as described above, but the particle size can be controlled by adjusting the reaction conditions, for example, the reaction time and the temperature rising time. The particle size can be reduced by shortening.

・ Process (3):
In the step (3), separately from the above steps (1) and (2), the raw iron compound and the raw material silicon compound are dissolved or dispersed in the aqueous dispersion medium to prepare a solution or dispersion of the iron component and the silicon component. To manufacture.

Examples of the raw material iron compound include the above-mentioned iron compounds, for example, iron metal alone (Fe), oxides (Fe ₂ O ₃ , Fe ₃ O ₄ ), and hydroxides (Fe (OH) ₂ , Fe (OH) _3). ), Oxyhydroxide (FeO (OH)), chloride (FeCl ₂ , FeCl ₃ ), nitrate (Fe (NO) ₃ ), sulfate (FeSO ₄ , Fe ₂ (SO ₄ ) ₃ ), halogen (Br , I) Compounds, complex compounds and the like, and one or a combination of two or more of these may be used. Among them, oxides (Fe ₂ O ₃ , Fe ₃ O ₄ ), oxyhydroxides (FeO (OH)), chlorides (FeCl ₂ , FeCl ₃ ), nitrates (Fe (NO) ₃ ), sulfates ( It is preferable to use FeSO ₄ , Fe ₂ (SO ₄ ) _3).

Examples of the raw material silicon compound include the above-mentioned silicon compounds, for example, silicon metal alone (Si), oxide (SiO, SiO ₂ ), alkoxide (Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si ( OCH (CH ₃ ) ₂ ) ₄ ), silicates (sodium salt, potassium salt) and active silicon acid obtained by removing ions such as sodium and potassium from the silicate, and one or two of these. The above may be used in combination. Among them, it is preferable to use silicate (sodium silicate) or active silicic acid. Active silicate can be obtained, for example, by adding a cation exchange resin to an aqueous sodium silicate solution in which sodium silicate is dissolved in pure water to remove at least a part of the sodium ions. It is preferable to add the cation exchange resin so that the pH is 2 to 10, preferably 2 to 7.

The iron component and silicon component-containing solution or dispersion thus obtained may also contain an alkaline substance or an acidic substance for pH adjustment or the like, and the alkaline substance, the acidic substance, and the pH adjustment referred to here are the same as described above. Can be handled by. The pH of the iron component and silicon component-containing solution or dispersion is preferably 1 to 7, and more preferably 1 to 5.

The concentration of the raw iron compound in the solution or dispersion of the iron component and the silicon component produced in the step (3) is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass, and the raw material silicon compound concentration is It is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass.

Further, the solution or dispersion of the iron component and the silicon component may further dissolve or disperse the transition metal component (molybdenum, tungsten, vanadium).
Examples of the transition metal component include molybdenum, tungsten, and vanadium, and examples of the raw material compound thereof include those described above.
The amount of the transition metal component (molybdenum, tungsten, vanadium) added when the transition metal component (molybdenum, tungsten, vanadium) is further dissolved or dispersed in the solution or dispersion of the iron component and the silicon component produced in the step (3) is appropriately selected according to the type of the transition metal component. However, the molar ratio with titanium (Ti / transition metal) is preferably 10 to 10,000.
A plurality of transition metal components to be added to the titanium oxide particles can be selected from molybdenum, tungsten, and vanadium, and the amount of each component at that time can be selected from the above range. However, the molar ratio [Ti / (Mo + W + V)] of the total amount of each component to titanium is 10 or more and less than 10,000.

・ Process (4):
In the step (4), the titanium oxide particle dispersion obtained in the step (2) and the solution or dispersion of the iron component and the silicon component obtained in the step (3) are mixed. The mixing method is not particularly limited, and it may be a method of stirring with a stirrer or a method of dispersing with an ultrasonic disperser. The temperature at the time of mixing is 20 to 100 ° C., preferably 20 to 80 ° C., more preferably 20 to 40 ° C., and the time is preferably 1 minute to 3 hours. The mixing ratio may be such that the molar ratio of Ti, Fe, and Si in the titanium oxide particle dispersion is the molar ratio as described above.

The titanium oxide particle dispersions obtained in the above steps (1) to (4) may contain an alkaline substance or an acidic substance for pH adjustment or the like, and the pH adjusting agent is as described above. Can be used. Further, an ion exchange treatment or a filtration cleaning treatment may be performed to adjust the ion component concentration, or a solvent replacement treatment may be performed to change the solvent component. The pH of the titanium oxide particle dispersion is preferably 7-14, more preferably 8-12.

The mass of the titanium oxide particles contained in the titanium oxide particle dispersion can be calculated from the mass and concentration of the titanium oxide particle dispersion. The concentration of the titanium oxide particle dispersion is measured by sampling a part of the titanium oxide particle dispersion and heating it at 105 ° C. for 1 hour to volatilize the solvent, and then the mass of the non-volatile component (titanium oxide particles). It can be calculated from the mass of the titanium oxide particle dispersion liquid sampled according to the following equation.
Concentration of titanium oxide particle dispersion (%) = [mass of non-volatile content (g) / mass of titanium oxide particle dispersion (g)] × 100

As described above, the total concentration of the iron component, the silicon component, and the titanium oxide particles in the titanium oxide particle dispersion prepared in this manner is 0.01 to 0.01 to the ease of producing a photocatalytic thin film having a required thickness. 20% by mass is preferable, and 0.5 to 10% by mass is particularly preferable. Regarding the concentration adjustment, if the concentration is higher than the desired concentration, the concentration can be lowered by adding an aqueous solvent and diluting, and if the concentration is lower than the desired concentration, the aqueous solvent is volatilized or filtered. By doing so, the concentration can be increased. The concentration can be calculated as described above.

Further, when the above-mentioned binder for enhancing the film-forming property is added, the concentration of the above-mentioned binder solution (aqueous binder solution) is adjusted as described above so as to obtain a desired concentration after mixing. It is preferable to add it to the particle dispersion.
The silicon component contained in the titanium oxide particle dispersion suppresses the aggregation and precipitation of the titanium oxide particles and the iron component, and suppresses the decrease in photocatalytic activity, and at the same time when the titanium oxide particles and the iron component are mixed. It is to be added. On the other hand, the binder enhances the film-forming property of the titanium oxide particle dispersion liquid, and is added after the titanium oxide particle dispersion liquid is prepared and before coating, and the two are different.

<Titanium oxide particles>
The titanium oxide particles of the present invention are characterized in that a tin component and a transition metal that enhances visible light activity are solid-dissolved, and an iron component and a silicon component are attached to the surface. The iron component and the silicon component may be attached to at least a part of the surface of the titanium oxide particles, and may be attached to the entire surface. Further, the titanium oxide particles of the present invention may have at least one metal component selected from molybdenum, tungsten and vanadium components attached to the surface in addition to the iron component and the silicon component.

The method of adhering the iron component and the silicon component to the surface of the titanium oxide particles is not particularly limited, but a method of mixing in a solid state (mixing the titanium oxide particle powder and the powder composed of the iron component and the silicon component), a liquid. Method of mixing in a state (mixing a solution or dispersion of titanium oxide particle dispersion with iron component and silicon component), method of mixing solid and liquid (solution or dispersion of titanium oxide particle powder with iron component and silicon component) A liquid is mixed, or a powder composed of an iron component and a silicon component is mixed with a titanium oxide particle dispersion liquid). Since the silicon component plays a role of suppressing the aggregation of the iron component, it is preferable to mix the iron component and the silicon component in advance and then mix them with the titanium oxide particles.
Of these, the method of mixing in a liquid state is preferable, and the methods of steps (1) to (4) are more preferable, as in the method for producing the titanium oxide particle dispersion liquid described above.

At least a part of the mixed iron component and the silicon component may be attached to the surface of the titanium oxide particles, and all of the mixed iron component and the silicon component may be attached. Further, it is preferable that the iron component and the silicon component are directly attached to the surface of the titanium oxide particles.

<Photocatalyst thin film containing titanium oxide particles / member having a photocatalyst thin film on the surface>
The titanium oxide particle dispersion of the present invention can be used to form a photocatalytic film on the surface of various members. Here, various members are not particularly limited, and examples of the material of the member include an organic material and an inorganic material. These can have various shapes according to their respective purposes and uses.

Examples of the organic material include vinyl chloride resin (PVC), polyethylene (PE), polypropylene (PP), polycarbonate (PC), acrylic resin, polyacetal, fluororesin, silicone resin, and ethylene-vinyl acetate copolymer (EVA). , Acrylonitrile-butadiene rubber (NBR), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyvinyl butyral (PVB), ethylene-vinyl alcohol copolymer (EVOH), polyimide resin, polyphenylene sulfide (PPS), polyether Synthetic resin materials such as imide (PEI), polyether ether imide (PEEI), polyether ether ketone (PEEK), melamine resin, phenol resin, acrylonitrile-butadiene-styrene (ABS) resin, natural materials such as natural rubber, or Examples thereof include a semi-synthetic material of the synthetic resin material and a natural material. These may be commercialized into required shapes and configurations such as films, sheets, textile materials, textile products, other molded products, and laminates.

Examples of the inorganic material include non-metallic inorganic materials and metallic inorganic materials. Examples of the non-metallic inorganic material include glass, ceramics, stones and the like. These may be commercialized in various shapes such as tiles, glass, mirrors, walls, and design materials. Examples of the metal-inorganic material include cast iron, steel material, iron, iron alloy, aluminum, aluminum alloy, nickel, nickel alloy, zinc die cast and the like. These may be plated with the metal-inorganic material, may be coated with the organic material, or may be plated on the surface of the organic material or the non-metal-inorganic material.

Among the above-mentioned various members, the titanium oxide particle dispersion liquid of the present invention is particularly useful for producing a transparent photocatalyst thin film on a polymer film such as PET.

As a method for forming a photocatalytic thin film on the surface of various members, for example, a titanium oxide particle dispersion liquid is applied to the surface of the member by a known coating method such as spray coating or dip coating, and then far-infrared drying, IH drying, etc. It may be dried by a known drying method such as hot air drying, and various thicknesses of the photocatalyst thin film can be selected, but usually, the range of 10 nm to 10 μm is preferable.
As a result, the above-mentioned film of titanium oxide particles is formed. In this case, when the dispersion liquid contains the binder in the above-mentioned amount, a film containing the titanium oxide particles and the binder is formed.

The photocatalytic thin film thus formed is transparent and not only gives a good photocatalytic action in light in the ultraviolet region (wavelength 10 to 400 nm) as in the conventional case, but also obtains a sufficient photocatalytic action in the conventional photocatalyst. Even with light in the visible region (wavelength 400 to 800 nm), which could not be achieved, a better photocatalytic action can be obtained, and the various members on which the photocatalytic thin film is formed are organic substances adsorbed on the surface by the photocatalytic action of titanium oxide. Is decomposed more quickly, so that the effects of cleaning, deodorizing, antibacterial and the like on the surface of the member can be exhibited.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. Various measurements in the present invention were carried out as follows.

(1) Cumulative distribution diameters of 50% and 90% of titanium oxide particles in the dispersion liquid (D ₅₀ and D ₉₀ )
The titanium oxide particles D ₅₀ and D ₉₀ in the dispersion were measured by a dynamic light scattering method using laser light using a particle size distribution measuring device (ELSZ-2000ZS (manufactured by Otsuka Electronics Co., Ltd.)). It was calculated as 50% and 90% cumulative distribution diameter based on the volume.

(2) Acetaldehyde Gas Decomposition Performance Test of Photocatalyst Thin Film The activity of the photocatalyst thin film prepared by applying and drying the dispersion was evaluated by the decomposition reaction of acetaldehyde gas. The evaluation was performed by the batch type gas decomposition performance evaluation method.
Each titanium oxide particle dispersion prepared in the examples or comparative examples is coated on one surface of an A4 size (210 mm × 297 mm) PET film with a # 7 wire bar coater so that the dry mass of the titanium oxide particles is about 20 mg. A sample for evaluation was prepared by spreading and dried in an oven set at 80 ° C. for 1 hour to obtain a sample for evaluation of acetaldehyde gas decomposition performance.
Using this evaluation sample, the photocatalytic activity of titanium oxide particles was evaluated by the decomposition reaction of acetaldehyde gas. The evaluation was performed by the batch type gas decomposition performance evaluation method.
Specifically, after installing an evaluation sample in a stainless cell with a quartz glass window having a volume of 5 L, the cell is filled with acetaldehyde gas having an initial concentration adjusted to a humidity of 50%, and a light source installed above the cell. Illuminated with light. When acetaldehyde gas is decomposed by the photocatalytic action of titanium oxide, the concentration of acetaldehyde gas in the cell decreases. Therefore, the strength of photocatalytic activity can be confirmed by measuring the change in concentration. The acetaldehyde gas concentration was evaluated by measuring the time from the start of light irradiation until the acetaldehyde gas concentration became 1 ppm or less using a photoacoustic multi-gas monitor (trade name “INNOVA1412”, manufactured by LumaSense). The shorter the time, the higher the photocatalytic activity, and the longer the time, the lower the photocatalytic activity.

In the evaluation of photocatalytic activity under visible light irradiation, an LED (product model number "TH-211 x 200SW", CCS Co., Ltd., spectral distribution: 400 to 800 nm) was used as the light source, and it was visible under the condition of an illuminance of 20,000 Lx. Irradiated with light. At this time, the initial concentration of acetaldehyde in the cell was set to 5 ppm.
In addition, in the evaluation of photocatalytic activity under ultraviolet irradiation, a UV fluorescent lamp (product model number "FL10 BLB", Toshiba Lighting & Technology Corporation) was used as the light source, and ultraviolet rays were emitted under the condition of ^{irradiance of 0.5 mW / cm 2.} Irradiated. At this time, the initial concentration of acetaldehyde in the cell was set to 20 ppm.

(3) Identification of Crystal Phase of Titanium Oxide Particles The crystal phase of titanium oxide particles is obtained by powder X-ray diffraction of titanium oxide particle powder recovered by drying the obtained dispersion of titanium oxide particles at 105 ° C. for 3 hours (commodity). It was identified by measuring the name "desktop X-ray diffractometer D2 PHASER", Bruker AXS Co., Ltd.

(4) Preparation of Titanium Oxide Particle Dispersion Liquid [Preparation Example 1-1]
<Preparation of titanium oxide particle dispersion liquid in which tin and molybdenum are dissolved>
Tin (IV) chloride was added and dissolved in a 36% by mass aqueous solution of titanium (IV) chloride so that the Ti / Sn (molar ratio) was 20, and this was diluted 10-fold with pure water and then 10% by mass. Ammonia water was gradually added to neutralize and hydrolyze the mixture to obtain a tin-containing titanium hydroxide precipitate. The pH at this time was 8. The obtained precipitate was deionized by repeating addition of pure water and decantation. Molybdenum (VI) acid is added to the tin-containing titanium hydroxide precipitate after this deionization treatment so that the Ti / Mo (molar ratio) is 250 with respect to the Ti component in the titanium (IV) chloride aqueous solution. Sodium was added. Add 35% by mass hydrogen peroxide solution so that H ₂ O ₂ / (Ti + Sn + Mo) (molar ratio) is 10, and then stir at 60 ° C. for 2 hours to fully react, and contain orange transparent tin and molybdenum. A peroxotitanic acid solution (1a) was obtained.

400 mL of tin and molybdenum-containing peroxotitanic acid solution (1a) was charged into an autoclave having a volume of 500 mL, and this was hydrothermally treated for 90 minutes under the condition of 150 ° C., and then pure water was added to adjust the concentration. A dispersion liquid (titanium oxide concentration 1.2% by mass, pH 11) of titanium oxide particles (1A) in which tin and molybdenum were dissolved was obtained. When the powder X-ray diffraction measurement of the titanium oxide particles (1A) was performed, it was found that the observed peak was only that of rutile-type titanium oxide, and that tin and molybdenum were solidly dissolved in titanium oxide.

[Preparation Example 1-2]
<Preparation of titanium oxide particle dispersion liquid in which tin, molybdenum and tungsten are dissolved>
Tin chloride (IV) is added so that the Ti / Sn (molar ratio) is 10, and molybdenum (IV) is added to the tin-containing titanium hydroxide precipitate after deionization so that the Ti / Mo (molar ratio) is 100. The same as in Preparation Example 1-1 except that sodium tungsten (VI) was added so that the ratio of sodium VI) to Ti / W (molar ratio) was 250 and the hydrothermal treatment time was set to 120 minutes. , A dispersion of titanium oxide particles (1B) in which tin, molybdenum and tungsten were solid-dissolved (titanium oxide concentration 1.2% by mass, pH 10) was obtained. When the powder X-ray diffraction measurement of the titanium oxide particles (1B) was performed, it was found that the observed peak was only that of rutile-type titanium oxide, and that tin, molybdenum and tungsten were dissolved in titanium oxide. ..

[Preparation Example 1-3]
<Preparation of titanium oxide particle dispersion liquid in which tin, molybdenum and vanadium are dissolved>
Tin (IV) chloride was added and dissolved in a 36 mass% titanium (IV) chloride aqueous solution so that the Ti / Sn (molar ratio) was 33, and this was diluted 10-fold with pure water and then added to this aqueous solution. , 10% by mass of aqueous ammonia in which sodium vanadine (V) was added and dissolved so that the Ti / V (molar ratio) was 2,000 with respect to the Ti component in the titanium (IV) chloride aqueous solution was gradually added. By adding, neutralizing and hydrolyzing, a precipitate of titanium hydroxide containing tin and vanadium was obtained. The pH at this time was 8. The obtained precipitate was deionized by repeating addition of pure water and decantation. After this deionization treatment, sodium molybdenum (VI) is added to the titanium hydroxide precipitate containing tin and vanadium so that the Ti / Mo (molar ratio) is 500, and then H ₂ O ₂ / ( A 35% by mass hydrogen peroxide solution was added so that Ti + Sn + Mo + V) (molar ratio) was 10, and then the mixture was stirred at 50 ° C. for 3 hours to cause a sufficient reaction. (1c) was obtained.

400 mL of a peroxotitanic acid solution (1c) containing tin, molybdenum and vanadium is charged in an autoclave having a volume of 500 mL, and this is hydrothermally treated for 60 minutes under the condition of 160 ° C., and then pure water is added to adjust the concentration. A dispersion of titanium oxide particles (1C) in which tin, molybdenum and vanadium were dissolved (titanium oxide concentration 1.2% by mass, pH 10) was obtained. When powder X-ray diffraction measurement of titanium oxide particles (1C) was performed, the observed peaks were those of anatase-type titanium oxide and rutile-type titanium oxide, and tin, molybdenum and vanadium were dissolved in titanium oxide. It turned out.

[Preparation Example 1-4]
<Preparation of titanium oxide particle dispersion liquid in which tin and molybdenum are dissolved>
Tin (IV) chloride was added and dissolved in a 36% by mass aqueous solution of titanium (IV) chloride so that Ti / Sn (molar ratio) was 20, and this was diluted 10-fold with pure water and then 10% by mass. Ammonia water was gradually added to neutralize and hydrolyze the mixture to obtain a tin-containing titanium hydroxide precipitate. The pH at this time was 8. The obtained precipitate was deionized by repeating addition of pure water and decantation. Molybdenum (VI) acid is added to the tin-containing titanium hydroxide precipitate after this deionization treatment so that the Ti / Mo (molar ratio) is 50 with respect to the Ti component in the titanium (IV) chloride aqueous solution. Sodium was added. Add 35% by mass hydrogen peroxide solution so that H ₂ O ₂ / (Ti + Sn + Mo) (molar ratio) is 12, and then stir at 60 ° C. for 2 hours to fully react, and contain orange transparent tin and molybdenum. A peroxotitanic acid solution (1d) was obtained.

400 mL of tin and molybdenum-containing peroxotitanic acid solution (d) was charged into an autoclave having a volume of 500 mL, and this was hydrothermally treated for 90 minutes under the condition of 150 ° C., and then pure water was added to adjust the concentration. A dispersion liquid (titanium oxide concentration 1.2% by mass, pH 11) of titanium oxide particles (1D) in which tin and molybdenum were dissolved was obtained. When the powder X-ray diffraction measurement of the titanium oxide particles (1D) was performed, it was found that the observed peak was only that of rutile-type titanium oxide, and that tin and molybdenum were solidly dissolved in titanium oxide.

[Preparation Example 1-5]
<Preparation of titanium oxide particle dispersion liquid in which tin and tungsten are dissolved>
Tin (IV) chloride so that the Ti / Sn (molar ratio) is 50, and tungsten (the molar ratio) to the tin-containing titanium hydroxide precipitate after deionization so that the Ti / W (molar ratio) is 33. A dispersion liquid (titanium oxide concentration 1.2% by mass, pH 10) of titanium oxide particles (1E) in which tin and tungsten were solid-dissolved was prepared in the same manner as in Preparation Example 1-1 except that sodium VI) sodium acid was added. Obtained. When powder X-ray diffraction measurement of titanium oxide particles (1E) was performed, the observed peaks were only those of anatase type titanium oxide and rutile type titanium oxide, and tin and tungsten were solidly dissolved in titanium oxide. I found out.

[Preparation Example 1-6]
<Preparation of titanium oxide particle dispersion liquid in which tin is dissolved>
A dispersion of titanium oxide particles (1F) in which tin was dissolved in a solid solution (titanium oxide concentration 1.2% by mass, pH 10) in the same manner as in Preparation Example 1-1 except that sodium molybdenum (VI) was not added. ) Was obtained. When the powder X-ray diffraction measurement of the titanium oxide particles (1F) was performed, it was found that the observed peak was only that of rutile-type titanium oxide, and that tin was dissolved in titanium oxide.

[Preparation Example 1-7]
<Preparation of titanium oxide particle dispersion liquid in which molybdenum is dissolved>
A dispersion liquid of titanium oxide particles (1G) in which molybdenum was dissolved (titanium oxide concentration 1.2% by mass, pH 10) in the same manner as in Preparation Example 1-1 except that tin (IV) chloride was not added. Got When powder X-ray diffraction measurement of titanium oxide particles (1G) was performed, it was found that the observed peak was only that of anatase-type titanium oxide, and molybdenum was dissolved in titanium oxide.

[Preparation Example 1-8]
<Preparation of titanium oxide particle dispersion liquid in which tungsten is dissolved>
Prepared except that tin (IV) chloride was not added and sodium tungsten (VI) was added to the titanium hydroxide precipitate after deionization so that the Ti / W (molar ratio) was 100. In the same manner as in Example 1-5, a dispersion of titanium oxide particles (1H) in which tungsten was dissolved (titanium oxide concentration 1.2% by mass, pH 10) was obtained. When the powder X-ray diffraction measurement of the titanium oxide particles (1H) was performed, it was found that the observed peak was only that of the anatase type titanium oxide, and that tungsten was dissolved in titanium oxide.

[Preparation Example 1-9]
<Preparation of titanium oxide particle dispersion>
A 36% by mass titanium (IV) chloride aqueous solution is diluted 10-fold with pure water, and then 10% by mass of aqueous ammonia is gradually added for neutralization and hydrolysis to obtain a titanium hydroxide precipitate. rice field. The pH at this time was 8.5. The obtained precipitate was deionized by repeating addition of pure water and decantation. After this deionization treatment, 35% by mass hydrogen peroxide solution was added to the titanium hydroxide precipitate so that H ₂ O ₂ / Ti (molar ratio) was 8, and then the mixture was sufficiently stirred at 60 ° C. for 2 hours. To obtain a transparent orange peroxotitanic acid solution (1i).

Titanium oxide particles (titanium oxide particles (1i)) were prepared by charging 400 mL of a peroxotitanic acid solution (1i) into an autoclave having a volume of 500 mL, hydrothermally treating the solution (1i) at 130 ° C. for 90 minutes, and then adding pure water to adjust the concentration. A dispersion of 1I) (titanium oxide concentration 1.2% by mass, pH 11) was obtained. When the powder X-ray diffraction measurement of the titanium oxide particles (1I) was performed, the observed peak was only that of the anatase type titanium oxide.

[Preparation Example 1-10]
<Preparation of titanium oxide particle dispersion liquid in which iron and silicon are dissolved>
Iron (III) chloride was added to a 36 mass% titanium (IV) chloride aqueous solution so that the Ti / Fe (molar ratio) was 20, and this was diluted 10-fold with pure water. 10% by mass of aqueous ammonia to which sodium silicate was added and dissolved so that the Ti / Si (molar ratio) was 7.5 with respect to the Ti component in the titanium (IV) chloride aqueous solution was gradually added to neutralize. , A precipitate of titanium hydroxide containing iron and silicon was obtained by hydrolysis. The pH at this time was 8. The obtained precipitate was deionized by repeating addition of pure water and decantation. To the iron and silicon-containing titanium hydroxide precipitate after the deionization treatment _{, 35% by mass hydrogen peroxide solution was added so that H 2} O ₂ / (Ti + Fe + Si) (molar ratio) was 15, and then 50. The mixture was stirred at ° C. for 2 hours and reacted sufficiently to obtain a peroxotitanic acid solution (1 l) containing orange-transparent iron and silicon.

400 mL of an iron and silicon-containing peroxotitanic acid solution (1 l) was charged into an autoclave having a volume of 500 mL, and this was hydrothermally treated for 120 minutes under the condition of 130 ° C., and then pure water was added to adjust the concentration. A dispersion liquid (titanium oxide concentration 1.2% by mass, pH 11) of titanium oxide particles (1 L) in which iron and silicon were solid-solved was obtained. When the powder X-ray diffraction measurement of the titanium oxide particles (1 L) was carried out, it was found that the observed peak was only that of the anatase type titanium oxide, and iron and silicon were solidly dissolved in the titanium oxide.

Table 1 summarizes the raw material ratios of titanium oxide particles prepared in each preparation example, hydrothermal treatment conditions, and dispersed particle diameters (D ₅₀ , D ₉₀ ). The dispersed particle size was measured by a dynamic light scattering method using laser light (ELSZ-2000ZS (manufactured by Otsuka Electronics Co., Ltd.).

(5) Preparation of solution or dispersion of iron component and silicon component [Preparation Example 2-1]
<Preparation of aqueous solution of iron sulfate and active silicic acid>
A strongly acidic cation exchange resin (Amberjet 1024H, manufactured by Organo Co., Ltd.) was added to an aqueous solution of sodium silicate obtained by dissolving 0.34 g of JIS No. 3 sodium silicate ( _{29.1% by mass in terms of SiO 2) in 100 g of pure water.} After stirring, the ion exchange resin was filtered off to obtain an active silicic acid aqueous solution. By adding 0.13 g of ferric sulfate to this active silicic acid aqueous solution, an aqueous solution (2A) of iron sulfate and active silicic acid having a pH of 2.6 was obtained.

[Preparation Example 2-2]
<Preparation of aqueous solution of iron sulfate and active silicic acid>
A strongly acidic cation exchange resin (Amberjet 1024H, manufactured by Organo Co., Ltd.) was added to an aqueous solution of sodium silicate obtained by dissolving 3.43 g of JIS No. 3 sodium silicate ( _{converted to SiO 2) in 100 g of pure water, and the mixture was stirred.} An aqueous solution of active silicic acid was obtained by filtering the ion exchange resin. By adding 0.50 g of ferric sulfate to this active silicic acid aqueous solution, an aqueous solution (2B) of iron sulfate and active silicic acid having a pH of 1.9 was obtained.

[Preparation Example 2-3]
<Preparation of aqueous solution of iron sulfate and active silicic acid>
A strongly acidic cation exchange resin (Amberjet 1024H, manufactured by Organo Co., Ltd.) was added to an aqueous solution of sodium silicate obtained by dissolving 0.034 g of JIS No. 3 sodium silicate ( _{converted to SiO 2) in 100 g of pure water, and the mixture was stirred.} An aqueous solution of active silicic acid was obtained by filtering the ion exchange resin. By adding 0.025 g of ferric sulfate to this active silicic acid aqueous solution, an aqueous solution (2C) of iron sulfate and active silicic acid having a pH of 3.1 was obtained.

[Preparation Example 2-4]
<Preparation of aqueous solutions of iron sulfate, active silicic acid and molybdic acid>
By adding 0.34 g of sodium molybdenum (VI) dihydrate to the aqueous solution of iron sulfate and active silicic acid obtained in Preparation Example 2-1, an aqueous solution of iron sulfate, active silicic acid and molybdic acid having a pH of 2.5 was added. (2D) was obtained.

[Preparation Example 2-5]
<Preparation of aqueous solutions of iron sulfate, active silicic acid and tungstic acid>
By adding 0.071 g of sodium tungstic acid dihydrate to the aqueous solution of iron sulfate and active silicic acid obtained in Preparation Example 2-1, an aqueous solution of iron sulfate, active silicic acid and tungstic acid having a pH of 2.6 was added. (2E) was obtained.

[Preparation Example 2-6]
<Preparation of aqueous solutions of iron sulfate, active silicic acid and vanadate>
By adding 0.020 g of sodium vanazine (V) to the aqueous solution of iron sulfate and active silicic acid obtained in Preparation Example 2-1 to obtain an aqueous solution (2F) of iron sulfate, active silicic acid and vanadic acid having a pH of 2.6. Obtained.

[Preparation Example 2-7]
<Preparation of iron sulfate aqueous solution>
By adding 0.50 g of ferric sulfate to 100 g of pure water, an iron sulfate aqueous solution (2 G) having a pH of 1.8 was obtained.

[Preparation Example 2-8]
<Preparation of active silicic acid aqueous solution>
An active silicic acid aqueous solution (2H) having a pH of 3.8 was obtained in the same manner except that the iron sulfate aqueous solution was not added in Preparation Example 2-1.

(7) Preparation of Titanium Oxide Particle Dispersion Liquid [Example 1]
An aqueous solution of iron sulfate and active silicic acid (2A) is mixed with a dispersion of titanium oxide particles (1A) at 25 ° C. for 10 minutes at 25 ° C. so that Ti / Fe is 200 and Ti / Si is 75, and then solid. The fractional concentration was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (E-1) having a pH of 10.

[Example 2]
An aqueous solution of iron sulfate and active silicic acid (2B) is mixed with a dispersion of titanium oxide particles (1B) at 25 ° C. for 10 minutes at 25 ° C. so that Ti / Fe is 50 and Ti / Si is 8, and then solid. The fractional concentration was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (E-2) having a pH of 9.

[Example 3]
After mixing an aqueous solution of iron sulfate and active silicic acid (2C) in a dispersion of titanium oxide particles (1C) with a stirrer at 25 ° C. for 10 minutes so that Ti / Fe is 1,000 and Ti / Si is 752. The solid content concentration was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (E-3) having a pH of 10.

[Example 4]
An aqueous solution (2D) of iron sulfate, active silicic acid and molybdenum acid is added to a dispersion of titanium oxide particles (1A) at 25 ° C. for 10 minutes so that Ti / Fe is 200, Ti / Si is 75 and Ti / Mo is 90. After mixing with a stirrer, the solid content concentration was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (E-4) having a pH of 10.

[Example 5]
An aqueous solution (2E) of iron sulfate, active silicic acid and tungsten acid is added to a dispersion of titanium oxide particles (1A) at 25 ° C. for 10 minutes so that Ti / Fe is 200, Ti / Si is 75 and Ti / W is 360. After mixing with a stirrer, the solid content concentration was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (E-5) having a pH of 10.

[Example 6]
An aqueous solution (2F) of iron sulfate, active silicic acid and vanadic acid is added to the dispersion of titanium oxide particles (1A) at 25 ° C. so that Ti / Fe is 200, Ti / Si is 75 and Ti / V is 1,802. After mixing with a stirrer for 10 minutes, the solid content concentration was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (E-6) having a pH of 10.

[Example 7]
An aqueous solution of iron sulfate and active silicic acid (2A) is mixed with a dispersion of titanium oxide particles (1D) at 25 ° C. for 10 minutes at 25 ° C. so that Ti / Fe is 200 and Ti / Si is 75, and then solid. The fractional concentration was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (E-7) having a pH of 10.

[Example 8]
An aqueous solution of iron sulfate and active silicic acid (2A) is mixed with a dispersion of titanium oxide particles (1E) at 25 ° C. for 10 minutes at 25 ° C. so that Ti / Fe is 200 and Ti / Si is 75, and then solid. The fractional concentration was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (E-8) having a pH of 10.

[Example 9]
_{Tio 2} / SiO ₂ (mass ratio) is added to the titanium oxide particle dispersion (E-1) with a silicon compound (silica) binder (colloidal silica, trade name: Snowtex 20, manufactured by Nissan Chemical Industry Co., Ltd.). The mixture was added so as to be 1.5 and mixed at 25 ° C. for 10 minutes with a stirrer to obtain a titanium oxide particle dispersion (E-9) containing a binder.

[Comparative Example 1]
An aqueous solution of iron sulfate and active silicic acid (2A) is mixed with a dispersion of titanium oxide particles (1F) at 25 ° C. for 10 minutes at 25 ° C. so that Ti / Fe is 200 and Ti / Si is 75, and then solid. The fractional concentration was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (C-1) having a pH of 10.

[Comparative Example 2]
An aqueous solution of iron sulfate and active silicic acid (2B) is mixed with a dispersion of titanium oxide particles (1G) at 25 ° C. for 10 minutes at 25 ° C. so that Ti / Fe is 50 and Ti / Si is 8, and then solid. The fractional concentration was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (C-2) having a pH of 10.

[Comparative Example 3]
An aqueous solution of iron sulfate and active silicic acid (2C) is mixed with a dispersion of titanium oxide particles (1H) at 25 ° C. for 10 minutes at 25 ° C. so that Ti / Fe is 100 and Ti / Si is 752, and then solid. The fractional concentration was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (C-3) having a pH of 10.

[Comparative Example 4]
An aqueous solution of iron sulfate and active silicic acid (2A) is mixed with a dispersion of titanium oxide particles (1I) at 25 ° C. for 10 minutes at 25 ° C. so that Ti / Fe is 200 and Ti / Si is 75, and then solid. The fractional concentration was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (C-4) having a pH of 10.

[Comparative Example 5]
A dispersion of titanium oxide particles (1J) is mixed with a dispersion of titanium oxide particles (1A) at 25 ° C. for 10 minutes so that Ti / Fe is 200 and Ti / Si is 75, and then solid. The minute concentration was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (C-5) having a pH of 10.

[Comparative Example 6]
After mixing an aqueous solution of iron sulfate (2G) with a dispersion of titanium oxide particles (1A) at 25 ° C. for 10 minutes with a stirrer so that Ti / Fe becomes 50, the solid content concentration is 1% by mass with pure water. To obtain a titanium oxide particle dispersion (C-6) having a pH of 10. Titanium oxide particles aggregated and precipitated by the addition of iron sulfate. Further, when the titanium oxide particle dispersion liquid (C-6) was filtered through a PP filter having a pore size of 1 μm, the brown iron component was filtered off on the filter, and it was found that the iron component was also aggregated. ..

[Comparative Example 7]
After mixing an aqueous solution of active silicic acid (2H) with a dispersion of titanium oxide particles (1A) at 25 ° C. for 10 minutes with a stirrer so that Ti / Si becomes 75, the solid content concentration is 1% by mass with pure water. To obtain a titanium oxide particle dispersion (C-7) having a pH of 10.

[Comparative Example 8]
The solid content concentration of the dispersion liquid of titanium oxide particles (1A) was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion liquid (C-8) having a pH of 10.

[Comparative Example 9]
A silicon compound-based (silica-based) binder (colloidal silica, trade name: Snowtex 20, manufactured by Nissan Chemical Industry Co., Ltd.) is added to the titanium oxide particle dispersion (C-8) in TiO ₂ / SiO ₂ (mass ratio). Was added so as to be 1.5, and the mixture was mixed with a stirrer at 25 ° C. for 10 minutes to obtain a titanium oxide particle dispersion (C-9) containing a binder.

(8) Preparation of Sample Member with Photocatalytic Thin Film Each titanium oxide particle dispersion prepared in the above Example or Comparative Example is subjected to a photocatalyst containing 20 mg of photocatalytic titanium oxide particles in an A4 size PET film by a # 7 wire bar coater. The film was coated to form a thin film (thickness of about 80 nm) and dried in an oven set at 80 ° C. for 1 hour to obtain a sample member for evaluating acetaldehyde gas decomposition performance.

[Photocatalyst performance test under visible light irradiation]
The sample members having the photocatalytic thin films of Examples and Comparative Examples were subjected to an acetaldehyde decomposition test under visible light irradiation by an LED. The evaluation was based on the time required to reduce the initial concentration of acetaldehyde from 5 ppm to 1 ppm.
If it is not reduced to 1 ppm within 24 hours, "-" is displayed in the "Time required to decompose to 1 ppm" column in Tables 2 and 3, and "Concentration after 24 hours" is displayed. The concentration after 24 hours is displayed in the column.

Table 2 shows the types of titanium oxide particles and added metal components, the molar ratio of the metal in the added metal components to Ti in titanium oxide, the dispersed particle size (D ₅₀ , D ₉₀ ), and acetaldehyde gas decomposition under visible light irradiation. The test results are summarized. The dispersed particle size was measured by a dynamic light scattering method using laser light (ELSZ-2000ZS (manufactured by Otsuka Electronics Co., Ltd.).

As can be seen from the results of Examples 1 to 8 and Comparative Examples 1 to 4, by using titanium oxide particles in which both the tin component and the transition metal component that enhances visible light activity are solid-dissolved, the tin component and visible light are used. It was found that the photocatalytic activity under visible light irradiation was higher than that in the case of using titanium oxide in which either one or both of the transition metal components that enhance the activity were not solid-dissolved.

As can be seen from the results of Example 1 and Comparative Example 5, by using titanium oxide particles (1A) in which the iron component and the silicon component (2A) are adhered to the surface, the iron component and the silicon component are dissolved and oxidized. It was found that the photocatalytic activity under visible light irradiation was higher than that when the titanium particles (1J) were mixed with the titanium oxide particles (1A) and used.

As can be seen from the results of Example 1 and Comparative Example 6, when the iron component is added to the titanium oxide particles (1A), it is found that the aggregation / precipitation of the titanium oxide particles and the iron component can be suppressed by adding the iron component together with the silicon component. rice field.

As can be seen from the results of Example 1 and Comparative Examples 7 and 8, by adding both the iron component and the silicon component to the titanium oxide particles (1A), as compared with the case where only the silicon component or not both are added. It was found that the photocatalytic activity under visible light irradiation was high.

Further, as can be seen from the results of Examples 1 and 9 and Comparative Examples 8 and 9, titanium oxide particles having an iron component and a silicon component (2A) adhered to the surface thereof are similarly used in the photocatalyst thin film containing a binder. It was found that a photocatalytic thin film having high photocatalytic activity under visible light irradiation can be obtained.

From the above, it was confirmed that the photocatalytic performance of the titanium oxide particles in which the iron component and the silicon component are attached to the surface of the present invention and the tin component and the transition metal component that enhances the visible light activity are solid-dissolved is excellent.

[Photocatalyst performance test under UV irradiation]
The sample members having the photocatalytic thin films of Example 1, Example 9, Comparative Example 8 and Comparative Example 9 were subjected to an acetaldehyde decomposition test under irradiation with a UV fluorescent lamp. The evaluation was based on the time required to reduce the initial concentration of acetaldehyde from 20 ppm to 1 ppm.

Table 3 summarizes the types of titanium oxide particles and added metals, the molar ratio of metals in the added metal components to Ti in titanium oxide, dispersed particle diameters (D ₅₀ , D ₉₀ ), and acetaldehyde gas decomposition test results. The dispersed particle size was measured by a dynamic light scattering method using laser light (ELSZ-2000ZS (manufactured by Otsuka Electronics Co., Ltd.).

As can be seen from the results of Example 1 and Comparative Example 8, the titanium oxide particles (1A) alone were obtained by mixing the solution (2A) containing the iron component and the silicon component with the titanium oxide particles (1A). It was found that the activity was improved more than the photocatalytic activity.
Similarly, from the results of Example 9 and Comparative Example 9, the photocatalytic thin film containing the binder was also obtained by mixing the titanium oxide particles (1A) with the solution (2A) containing the iron component and the silicon component. It was found that the activity of the titanium oxide particles (1A) alone was significantly improved as compared with the photocatalytic activity of the particles (1A) alone.

The titanium oxide particle dispersion liquid of the present invention is useful for producing a photocatalytic thin film by applying it to various substrates composed of an inorganic substance such as glass or metal and an organic substance such as resin, and particularly various groups. It is useful for forming a transparent photocatalytic thin film on a material.

Claims (14)

1) The tin component and the transition metal component that enhances visible light activity are dissolved in solid solution.
2) Titanium oxide particles to which iron and silicon components are attached to the surface. The titanium oxide particles according to claim 1, wherein the transition metal component dissolved in the titanium oxide particles is at least one selected from vanadium, chromium, manganese, niobium, molybdenum, rhodium, tungsten and cerium. The titanium oxide particles according to claim 2, wherein the transition metal component dissolved in the titanium oxide particles is at least one selected from molybdenum, tungsten, and vanadium components. The titanium oxide particles according to any one of claims 1 to 3, wherein the amount of the tin component solidly dissolved in the titanium oxide particles is 1 to 1,000 in terms of molar ratio (Ti / Sn) with titanium. Any of claims 1 to 4, wherein the molar ratio (Ti / Fe) of the iron component to titanium is 10 to 10,000, and the molar ratio (Ti / Si) of the silicon component to titanium is 1 to 10,000. The titanium oxide particles according to item 1. The third aspect of claim 3, wherein the amounts of the molybdenum, tungsten, and vanadium components dissolved in the titanium oxide particles are 1 to 10,000 in terms of molar ratio with titanium (Ti / Mo or Ti / W or Ti / V). Titanium oxide particles. The titanium oxide particles according to any one of claims 1 to 6, further comprising at least one metal component selected from molybdenum, tungsten and vanadium components adhering to the surface.
A titanium oxide particle dispersion liquid in which the titanium oxide particles according to any one of claims 1 to 7 are dispersed in an aqueous dispersion medium. The titanium oxide particle dispersion liquid according to claim 8, further containing a binder. The titanium oxide particle dispersion liquid according to claim 9, wherein the binder is a silicon compound-based binder. A photocatalytic thin film containing the titanium oxide particles according to any one of claims 1 to 7. The photocatalytic thin film according to claim 11, further containing a binder. A member in which the photocatalytic thin film of claim 11 or 12 is formed on the surface of a base material. A method for producing a titanium oxide particle dispersion liquid, which comprises the following steps (1) to (4).
(1) Step of producing a peroxotitanic acid solution containing a tin component and a transition metal component from a raw material titanium compound, a tin compound, a transition metal compound, a basic substance, hydrogen peroxide and an aqueous dispersion medium (2) The above (1) A step of heating a peroxotitanic acid solution containing a tin component and a transition metal component produced in the step at 80 to 250 ° C. under pressure control to obtain a titanium oxide particle dispersion containing a tin component and a transition metal component (3) Iron compound , A step of producing a solution or dispersion of an iron component and a silicon component from a silicon compound and an aqueous dispersion medium (4) A titanium oxide particle dispersion produced in the above step (2) and a step (3). Step of mixing a solution or dispersion of an iron compound and a silicon compound to obtain a dispersion