Titanium oxide particles, dispersion liquid thereof, photocatalyst film, member having photocatalyst film on surface, and method for producing titanium oxide particle dispersion liquid

Abstract

The present application provides a kind of titanium oxide particles, its dispersion, the photocatalyst film formed using the dispersion, the component with photocatalyst film on surface and the manufacturing method of titanium oxide particle dispersion, which is higher than the photocatalytic activity of the past, especially the visible light activity of the past is higher. Wherein, the titanium oxide particles, 1) solid solution has tin component and transition metal component for improving visible light activity, 2) iron component, titanium component and silicon component are attached to its surface, and the titanium oxide particle dispersion is formed by dispersing the titanium oxide particles in aqueous dispersion medium.

Description

Technical Field

[0001] This invention relates to titanium oxide particles, their dispersion, photocatalyst films, components having photocatalyst films on their surfaces, and methods for manufacturing titanium oxide particle dispersions. More specifically, it relates to visible light responsive photocatalytic titanium oxide particles that can express photocatalytic activity only in visible light (wavelength 400-800 nm) and can be easily fabricated into highly transparent photocatalyst films. Background Technology

[0002] Photocatalysts are widely used for cleaning, deodorizing, and antibacterial purposes on component surfaces. The photocatalytic reaction refers to the reaction that occurs when excited electrons and electron holes are generated by the absorption of light by the photocatalyst. It can be considered that the degradation of organic matter caused by photocatalysts is mainly initiated by the following mechanisms (1) and (2).

[0003] (1) The generated excited electrons and electron holes react with oxygen or water adsorbed on the surface of the photocatalyst in a redox reaction, and the active substances generated by the redox reaction degrade organic matter.

[0004] (2) The generated electron holes directly oxidize and degrade the organic matter adsorbed on the surface of the photocatalyst.

[0005] Recently, the applicability of photocatalysts, as described above, has been explored not only in outdoor environments where ultraviolet light can be utilized, but also in indoor spaces where light sources in the visible range (wavelength 400–800 nm), such as fluorescent lamps, predominate. For example, tungsten oxide photocatalysts have been developed as visible light responsive photocatalysts (Japanese Patent Application Laid-Open No. 2009-148700: Patent Document 1), but since tungsten is a rare element, it is anticipated that the visible light activity of photocatalysts using titanium, a common element, can be improved.

[0006] As methods to improve the visible light activity of photocatalysts using titanium dioxide, known methods include loading iron or copper onto the surface of titanium dioxide particles or titanium dioxide particles doped with metals (e.g., Japanese Patent Application Publication No. 2012-210632: Patent Document 2, Japanese Patent Application Publication No. 2010-104913: Patent Document 3; Japanese Patent Application Publication No. 2011-240247: Patent Document 4, Japanese Patent Application Publication No. 7-303835: Patent Document 5), mixing titanium dioxide particles doped with tin and transition metals for improving visible light activity and titanium dioxide particles doped with copper after preparing them separately (International Publication No. 2014 / 045861: Patent Document 6), and mixing titanium dioxide particles doped with tin and transition metals for improving visible light responsiveness and titanium dioxide particles doped with iron group elements after preparing them separately (International Publication No. 2016 / 152487: Patent Document 7), etc.

[0007] When using the latter method (Patent Document 7), a photocatalyst film is prepared by mixing titanium oxide particles containing dissolved tin and transition metals with visible light activity, and titanium oxide particles containing dissolved iron group elements, to obtain a visible light-responsive titanium oxide particle dispersion. High degradation activity is only achieved under visible light conditions. However, when using a photocatalyst film prepared by adsorbing (i.e. supporting) iron components on the surface of titanium oxide particles containing dissolved tin and transition metals with visible light activity, although acetaldehyde gas degradation is shown to occur only under visible light conditions, the amount of iron is limited due to the aggregation and precipitation of the titanium oxide particles, which impairs the quality of the resulting photocatalyst film and consequently results in low photocatalytic activity.

[0008] As mentioned above, although research on improving photocatalytic activity is actively underway, further improvements in photocatalytic activity are required because it is important to degrade and remove harmful substances as quickly as possible in real-world environments.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2009-148700

[0012] Patent Document 2: Japanese Patent Application Publication No. 2012-210632

[0013] Patent Document 3: Japanese Patent Application Publication No. 2010-104913

[0014] Patent Document 4: Japanese Patent Application Publication No. 2011-240247

[0015] Patent Document 5: Japanese Patent Application Publication No. 7-303835

[0016] Patent Document 6: International Publication No. 2014 / 045861

[0017] Patent Document 7: International Publication No. 2016 / 152487 Summary of the Invention

[0018] The problem that the invention aims to solve

[0019] Therefore, the object of the present invention is to provide titanium oxide particles that can obtain higher photocatalytic activity than before, especially visible light activity, a dispersion thereof, a photocatalytic thin film formed using said dispersion, a component having a photocatalytic thin film on its surface, and a method for manufacturing a titanium oxide particle dispersion.

[0020] Problem Solving Methods

[0021] To achieve the above objectives, the inventors conducted a detailed study on the metal elements and their combinations dissolved in titanium oxide particles, the metal elements and their combinations added to titanium oxide particles, and their proportions. The results showed that titanium oxide particles with iron, titanium, and silicon components attached to the surface of titanium oxide particles with specific metals dissolved in them can dramatically improve photocatalytic activity, especially visible light activity, thus completing the present invention.

[0022] Therefore, the present invention provides titanium oxide particles as shown below, a dispersion thereof, a photocatalyst film formed using the dispersion, a component having a photocatalyst film on its surface, and a method for manufacturing a titanium oxide particle dispersion.

[0023] [1] A titanium dioxide particle, wherein,

[0024] 1) It contains tin in solid solution and transition metal components to enhance visible light activity.

[0025] 2) Its surface is coated with iron, titanium and silicon components.

[0026] [2] According to the titanium oxide particles described in [1], wherein,

[0027] The transition metal component dissolved in the titanium dioxide particles to enhance visible light activity is at least one selected from vanadium, chromium, manganese, niobium, molybdenum, rhodium, tungsten, and cerium.

[0028] [3] According to the titanium oxide particles described in [2], wherein,

[0029] The transition metal component dissolved in the titanium dioxide particles to enhance visible light activity is at least one selected from molybdenum, tungsten, and vanadium.

[0030] [4] Titanium oxide particles according to any one of [1] to [3], wherein,

[0031] The content of tin dissolved in titanium oxide particles, expressed as a molar ratio (TiO2 / Sn) to titanium oxide, is 1–1000.

[0032] [5] Titanium oxide particles according to any one of [1] to [4], wherein,

[0033] The molar ratio of iron to titanium oxide (TiO2 / Fe) is 10–10000, the molar ratio of titanium to titanium oxide (TiO2 / Ti) is 10–10000, and the molar ratio of silicon to titanium oxide (TiO2 / Si) is 1–10000.

[0034] [6] According to the titanium oxide particles described in [3], wherein,

[0035] The contents of molybdenum, tungsten and vanadium dissolved in titanium oxide particles, respectively, are 1 to 10000 in molar ratio to titanium oxide (TiO2 / Mo, TiO2 / W or TiO2 / V).

[0036] [7] A titanium dioxide particle dispersion, wherein...

[0037] The titanium oxide particles described in any one of [1] to [6] are dispersed in an aqueous dispersion medium.

[0038] [8] According to the titanium dioxide particle dispersion described in [7], wherein,

[0039] It further contains adhesives.

[0040] [9] According to the titanium dioxide particle dispersion described in [8], wherein,

[0041] The adhesive is a silicone compound adhesive.

[0042]

[10] A photocatalyst thin film, wherein,

[0043] Contains titanium oxide particles as described in any one of [1] to [6].

[0044]

[11] According to the photocatalyst film described in

[10] , wherein,

[0045] It further contains adhesives.

[0046]

[12] A component, wherein,

[0047] It has a photocatalyst film as described in

[10] or

[11] on its surface.

[0048]

[13] A method for manufacturing a titanium oxide particle dispersion as described in any one of [7] to [9], comprising the following steps (1) to (4), wherein,

[0049] (1) A process for manufacturing a peroxytitanic acid solution containing tin and transition metal components from raw materials titanium compounds, tin compounds, transition metal compounds, alkaline substances, hydrogen peroxide and an aqueous dispersion medium.

[0050] (2) A process of heating the peroxytitanic acid solution containing tin and transition metal components produced in the above (1) process under pressure control and at 80 to 250°C to obtain a titanium oxide particle dispersion containing tin and transition metal components.

[0051] (3) A process of manufacturing a solution or a dispersion containing iron, titanium and silicon components from iron compounds, titanium compounds, silicon compounds and an aqueous dispersion medium.

[0052] (4) A process of mixing the titanium oxide particle dispersion produced in step (2) above with a solution containing iron compound, titanium compound and silicon compound or a dispersion containing iron compound, titanium compound and silicon compound produced in step (3) to obtain a dispersion.

[0053] Invention Effects

[0054] The titanium dioxide particles of the present invention exhibit higher photocatalytic activity than those of the past, particularly under visible light (wavelength 400–800 nm). Furthermore, highly transparent photocatalyst films can be easily fabricated from a dispersion of these titanium dioxide particles. Therefore, the titanium dioxide particles of the present invention are useful for components used in indoor spaces illuminated primarily by visible light sources such as fluorescent lamps or white LEDs. Detailed Implementation

[0055] The present invention will now be described in detail.

[0056] Titanium oxide particle dispersion

[0057] The titanium dioxide particle dispersion of the present invention is a dispersion containing 1) titanium dioxide particles with a solid solution of tin and a transition metal component for improving visible light activity, and 2) iron, titanium, and silicon components in an aqueous dispersion medium. The iron, titanium, and silicon components contained in the titanium dioxide particle dispersion adhere to the surface of the titanium dioxide particles, but they can also be free in the titanium dioxide particle dispersion.

[0058] Water is preferred as the aqueous dispersion medium, but hydrophilic organic solvents mixed with water in any proportion and mixed solvents with water can also be used. As water, purified water, such as filtered water, deionized water, distilled water, or pure water, is preferred. As the hydrophilic organic solvent, alcohols such as methanol, ethanol, and isopropanol are preferred; glycols such as ethylene glycol; and ethylene glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and propylene glycol n-propyl ether are preferred. When using a mixed solvent, the proportion of the hydrophilic organic solvent in the mixed solvent is greater than 0% by mass, preferably 50% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0059] The titanium oxide particles are titanium oxide particles that have been dissolved in tin and transition metals to improve visible light activity in titanium oxide used as a photocatalyst. The titanium oxide particle dispersion of the present invention "contains iron, titanium and silicon" means that the dispersion contains the iron, titanium and silicon components.

[0060] As for the crystal phase of titanium oxide particles, rutile, anatase, and brookite are generally known. The titanium oxide particles of the present invention are preferably mainly rutile or anatase, and particularly preferably mainly rutile. It should be noted that the term "mainly" here means that the titanium oxide particles contain 50% or more of this crystal phase in the overall crystal structure, preferably 70% or more of this crystal phase, more preferably 90% or more of this crystal phase, and may also contain 100% of this crystal phase.

[0061] In this specification, a solid solution refers to a phase in which atoms at the lattice points of a certain crystal phase are replaced by other atoms, or other atoms are incorporated into the interstitial spaces of the lattice; that is, a mixed phase in which other substances are dissolved into a certain crystal phase; it also refers to a homogeneous phase as the crystal phase. A solid solution in which solvent atoms at the lattice points are replaced by solute atoms is called a substitutional solid solution, and a solid solution in which solute atoms are dissolved into the interstitial spaces of the lattice is called an interstitial solid solution. In this specification, it refers to any one of these types of solid solutions.

[0062] The titanium oxide particles of the present invention are characterized in that the titanium oxide particles form a solid solution with tin atoms and transition metal atoms for improving visible light responsivity. The solid solution can be either substitutional or interstitial. A substitutional solid solution of titanium oxide is formed by the replacement of titanium sites in the titanium oxide crystal with various metal atoms, while an interstitial solid solution of titanium oxide is formed by the dissolution of various metal atoms in the interstitial spaces of the titanium oxide crystal lattice. If various metal atoms are dissolved in titanium oxide, when the crystal phase is measured by X-ray diffraction or the like, only the crystal phase peaks of titanium oxide are observed, and the peaks of compounds from the added metal atoms are not observed.

[0063] There are no particular limitations on the methods for dissolving dissimilar metals in metal oxide crystals. Examples include gas-phase methods (CVD, PVD, etc.), liquid-phase methods (hydrothermal methods, sol-gel methods, etc.), and solid-phase methods (high-temperature sintering, etc.).

[0064] The tin component dissolved in the titanium dioxide particles can be used to improve the visible light responsiveness of the photocatalytic film, but any component derived from a tin compound is acceptable. Examples include elemental tin (Sn), tin oxides (SnO, SnO2), tin hydroxides, tin chlorides (SnCl2, SnCl4), tin nitrates (Sn(NO3)2), tin sulfates (SnSO4), tin halides (Br, I) other than chlorides, tin oxyacid salts (Na2SnO3, K2SnO3), and tin complexes. One or a combination of two or more of these compounds can be used. Among these, tin oxides (SnO, SnO2), tin chlorides (SnCl2, SnCl4), tin sulfates (SnSO4), and tin oxyacid salts (Na2SnO3, K2SnO3) are preferred.

[0065] The amount of tin dissolved in the titanium oxide particles, in terms of the molar ratio (TiO2 / Sn) to titanium oxide, is 1 to 1000, preferably 5 to 500, and more preferably 5 to 100. This is because when the amount of tin in the molar ratio to titanium oxide is less than 1, the proportion of titanium oxide decreases, sometimes failing to fully realize the photocatalytic effect; when the amount of tin in the molar ratio to titanium oxide exceeds 1000, the visible light responsiveness sometimes becomes insufficient.

[0066] The transition metal dissolved in the titanium oxide particles is a transition metal used to improve the visible light responsiveness of the photocatalyst film. It is one or more elements selected from Groups 3 to 11 of the periodic table, and can be selected from vanadium, chromium, manganese, niobium, molybdenum, rhodium, tungsten, cerium, etc., with molybdenum, tungsten and vanadium being preferred.

[0067] The transition metal component dissolved in the titanium oxide particles can be any component derived from the transition metal compound. Examples include metals of transition metals, oxides of transition metals, hydroxides of transition metals, chlorides of transition metals, nitrates of transition metals, sulfates of transition metals, halides (Br, I) other than chlorides of transition metals, oxoacid salts of transition metals, and various complexes of transition metals. One or more of these compounds can be used.

[0068] The amount of transition metal component dissolved in titanium oxide particles can be appropriately selected according to the type of transition metal component, but it is preferably 1 to 10000 in terms of the molar ratio (TiO2 / transition metal) with titanium oxide.

[0069] When molybdenum is selected as the transition metal component dissolved in titanium dioxide particles, the molybdenum component can be any component derived from molybdenum compounds. Examples include elemental molybdenum (Mo), molybdenum oxides (MoO2, MoO3), molybdenum hydroxides, molybdenum chlorides (MoCl3, MoCl5), molybdenum nitrates, molybdenum sulfates, halides (Br, I) other than molybdenum chlorides, molybdic acids (oxyacids) of molybdenum and their molybdenum salts (H2MoO4, Na2MoO4, K2MoO4), and molybdenum complexes. One or more of these components can be used. Among these, molybdenum oxides (MoO2, MoO3), molybdenum chlorides (MoCl3, MoCl5), molybdenum oxyacids, and their molybdenum salts (H2MoO4, Na2MoO4, K2MoO4) are preferred.

[0070] The amount of molybdenum dissolved in the titanium oxide particles, expressed as a molar ratio (TiO2 / Mo) to titanium oxide, is preferably 1 to 10,000, more preferably 5 to 5,000, and even more preferably 20 to 1,000. This is because when the molar ratio is less than 1, the proportion of titanium oxide decreases, sometimes failing to fully realize the photocatalytic effect; and when the molar ratio exceeds 10,000, the visible light responsiveness sometimes becomes insufficient.

[0071] When tungsten is selected as the transition metal component dissolved in titanium dioxide particles, any component derived from tungsten compounds may be used. Examples include elemental tungsten (W), tungsten oxide (WO3), tungsten hydroxide, tungsten chloride (WCl4, WCl6), tungsten nitrate, tungsten sulfate, halides (Br, I) other than tungsten chloride, tungsten tungstate and tungsten oxyacid salts (H2WO4, Na2WO4, K2WO4), and tungsten complexes. One or a combination of two or more of these components may be used. Among these, tungsten oxide (WO3), tungsten chloride (WCl4, WCl6), and tungsten oxyacid salts (Na2WO4, K2WO4) are preferred.

[0072] The amount of tungsten dissolved in the titanium oxide particles, in terms of the molar ratio (TiO2 / W) to titanium oxide, is preferably 1 to 10,000, more preferably 5 to 5,000, and even more preferably 20 to 2,000. This is because when the molar ratio is less than 1, the proportion of titanium oxide decreases, sometimes failing to fully realize the photocatalytic effect; and when the molar ratio exceeds 10,000, the visible light responsiveness sometimes becomes insufficient.

[0073] When vanadium is selected as the transition metal component dissolved in titanium dioxide particles, the vanadium component can be any component derived from vanadium compounds. Examples include elemental vanadium (V), vanadium oxides (VO, V₂O₃, VO₂, V₂O₅), vanadium hydroxides, vanadium chlorides (VCl₅), vanadium oxychlorides (VOCl₃), vanadium nitrates, vanadium sulfates, vanadium oxysulfates (VOSO₄), vanadium halides (Br, I) other than chlorides, vanadium oxyacidates (Na₃VO₄, K₃VO₄, KVO₃), and vanadium complexes. One or more of these components can be used. Among these, vanadium oxides (V₂O₃, V₂O₅), vanadium chlorides (VCl₅), vanadium oxychlorides (VOCl₃), vanadium oxysulfates (VOSO₄), and vanadium oxyacidates (Na₃VO₄, K₃VO₄, KVO₃) are preferred.

[0074] The amount of vanadium dissolved in the titanium oxide particles, in terms of the molar ratio (TiO2 / V) to titanium oxide, is preferably 1 to 10,000, more preferably 10 to 10,000, and even more preferably 100 to 10,000. This is because when the molar ratio is less than 1, the proportion of titanium oxide decreases, sometimes failing to fully realize the photocatalytic effect; and when the molar ratio exceeds 10,000, the visible light responsiveness sometimes becomes insufficient.

[0075] As a transition metal component dissolved in titanium oxide particles, multiple elements such as molybdenum, tungsten, and vanadium can be selected, and the amounts of each component can be chosen from the ranges mentioned above. However, the total amount of each component and the molar ratio of titanium oxide [TiO2 / (Mo+W+V)] should be greater than 1 and less than 10000.

[0076] One type of titanium dioxide particle can be used, or two or more types can be combined. Combining two or more types of titanium dioxide particles with different visible light responsiveness can improve visible light activity.

[0077] The iron, titanium, and silicon components contained in the titanium oxide particle dispersion and attached to the surface of the titanium oxide particles are components that can improve the visible light responsiveness of the photocatalyst film.

[0078] The iron component in the titanium dioxide particle dispersion is a component that enhances the photocatalytic activity of the photocatalyst film. Any component derived from iron compounds is acceptable, including, for example, elemental iron (Fe), iron oxides (Fe₂O₃, Fe₃O₄), iron hydroxides (Fe(OH)₂, Fe(OH)₃), iron hydroxyoxides (FeO(OH)), iron chlorides (FeCl₂, FeCl₃), iron nitrates (Fe(NO)₃), iron sulfates (FeSO₄, Fe₂(SO₄)₃), halides (Br, I) other than iron chlorides, and iron complexes. One or more of these components can be used in combination.

[0079] The iron content in the titanium oxide particle dispersion, based on the molar ratio of iron to titanium oxide (TiO2 / Fe), is preferably 10 to 10,000, more preferably 20 to 5,000, and even more preferably 50 to 2,000. This is because when the molar ratio of iron to titanium oxide is less than 10, titanium oxide aggregates and precipitates, reducing the quality of the resulting photocatalytic film and sometimes failing to fully realize the photocatalyst's effect; when the molar ratio of iron to titanium oxide exceeds 10,000, the visible light responsiveness may sometimes become insufficient.

[0080] The titanium component contained in the titanium oxide particle dispersion is used to improve the photocatalytic activity of the photocatalyst film. Any component derived from titanium compounds is acceptable, such as elemental titanium (Ti), titanium hydroxide (Ti(OH)4), titanium hydroxyoxide (TiO(OH)2), titanium chloride (TiCl4, TiCl3, TiCl2), titanium nitrate (Ti(NO)4), titanium sulfate (Ti(SO4)2, TiOSO4), halides (Br, I) other than titanium chloride, and titanium complexes. One of these components or a combination of two or more of them can be used.

[0081] The content of titanium in the titanium oxide particle dispersion, based on the molar ratio of titanium to titanium oxide (TiO2 / Ti), is preferably 10 to 10,000, more preferably 20 to 5,000, and even more preferably 50 to 2,000. This is because when the molar ratio of titanium to titanium oxide is less than 10, titanium oxide aggregates and precipitates, reducing the quality of the resulting photocatalytic film and sometimes failing to fully realize the photocatalyst's effect; when the molar ratio of iron to titanium exceeds 10,000, the effect of improving activity sometimes becomes insufficient.

[0082] The silicon component contained in the titanium dioxide particle dispersion is a component that inhibits the aggregation and precipitation of titanium dioxide, iron, and titanium components when iron and titanium components are added, thereby preventing a decrease in the quality of the photocatalyst film and thus suppressing a decrease in photocatalytic effect. Any component derived from a silicon compound is acceptable. Examples of silicon compounds include, for instance, elemental silicon (Si), silicon oxides (SiO, SiO2), silicon alkoxides (Si(OCH3)4, Si(OC2H5)4, Si(OCH(CH3)2)4), silicates (sodium salts, potassium salts), and active silicic acid from which at least some sodium or potassium ions have been removed. One of these or a combination of two or more can be used. Among these, silicates (sodium silicate) or active silicic acid are preferred, and active silicic acid is particularly preferred.

[0083] The silicon content in the titanium oxide particle dispersion, based on the molar ratio of silicon to titanium oxide (TiO2 / Si), is preferably 1 to 10,000, more preferably 2 to 5,000, and even more preferably 5 to 2,000. This is because when the molar ratio of silicon to titanium oxide is less than 1, the proportion of titanium oxide decreases, sometimes failing to fully realize the photocatalytic effect; and when the molar ratio of silicon to titanium oxide exceeds 10,000, the effect of inhibiting the aggregation and precipitation of titanium oxide sometimes becomes insufficient.

[0084] The 50% cumulative distribution diameter (hereinafter sometimes denoted as D) of titanium oxide particles in a dispersion containing iron, titanium, and silicon, measured using laser dynamic light scattering on a volume basis. 50 The preferred nm range is 3–50 nm, more preferably 3–30 nm, and even more preferably 3–20 nm. This is because, in D… 50 In the case of nanometers smaller than 3nm, photocatalytic activity may sometimes become insufficient; while in D... 50 When the wavelength exceeds 50 nm, the dispersion may become opaque.

[0085] The 90% cumulative distribution diameter of the volume datum (sometimes denoted as D below) 90 The preferred wavelengths are 5–100 nm, and more preferably 5–80 nm. This is because, in D… 90 In the case of nanometers smaller than 5nm, photocatalytic activity may sometimes become insufficient; while in D... 90 At wavelengths exceeding 100 nm, the dispersion may become opaque.

[0086] The titanium dioxide particles of this invention are D 50 and D 90 Particles within the above-mentioned range are preferred, as they form a dispersion with high photocatalytic activity and high transparency.

[0087] It should be noted that D, used to determine the titanium dioxide particles in the above-mentioned titanium dioxide particle dispersion, 50 and D 90 The device can be, for example, ELSZ-2000ZS (manufactured by Otsuka Electronics Co., Ltd., Japan), Nanotrac UPA-EX150 (manufactured by Nikkiso Co., Ltd., Japan), LA-910 (manufactured by Horiba Seisakusho Co., Ltd., Japan), etc.

[0088] From the viewpoint of ease of fabricating photocatalyst films of the required thickness, the concentration of titanium oxide particles in the titanium oxide particle dispersion is preferably 0.01 to 20% by mass, and particularly preferably 0.5 to 10% by mass.

[0089] Furthermore, an adhesive can be added to the titanium dioxide particle dispersion to facilitate both application of the dispersion to the surfaces of the various components described later and adhesion of the particles. Examples of adhesives include, for instance, metal compound adhesives containing silicon, aluminum, titanium, zirconium, etc., and organic resin adhesives containing fluorine resins, acrylic resins, polyurethane resins, etc.

[0090] The mass ratio of the binder to titanium oxide [titanium oxide / binder] is preferably in the range of 99 to 0.01, more preferably in the range of 9 to 0.1, and even more preferably in the range of 2.5 to 0.4. This is because when the mass ratio exceeds 99, the adhesion of titanium oxide particles to the surfaces of various components may become insufficient, and when the mass ratio is less than 0.01, the visible light activity may become insufficient.

[0091] In order to obtain a photocatalyst film with excellent photocatalytic activity and transparency, it is particularly preferred that a silicon compound binder be added and used, with a mass ratio (titanium oxide / silicon compound binder) in the range of 99 to 0.01, more preferably in the range of 9 to 0.1, and even more preferably in the range of 2.5 to 0.4. The silicon compound binder refers to a colloidal dispersion, solution, or emulsion of a silicon compound formed by containing solid or liquid silicon compounds in an aqueous dispersion medium. Specifically, examples include colloidal silica (preferably with a particle size of 1 to 150 nm); silicate solutions such as silicates; silane and siloxane hydrolysate emulsions; organosilicon resin emulsions; organosilicon-acrylic resin copolymers, organosilicon-polyurethane resin copolymers, and emulsions of copolymers of organosilicon resins and other resins.

[0092] <Preparation Method of Titanium Oxide Particle Dispersion>

[0093] The method for manufacturing the titanium oxide particle dispersion of the present invention is as follows: titanium oxide particle dispersion and a solution containing iron, titanium and silicon or a dispersion containing iron, titanium and silicon are manufactured separately, and the titanium oxide particle dispersion and the solution containing iron, titanium and silicon or the dispersion containing iron, titanium and silicon are mixed together.

[0094] A method for manufacturing a titanium oxide particle dispersion containing iron, titanium and silicon components as a solid solution tin component and a transition metal component for improving visible light responsiveness can be specifically described as a manufacturing method having the following steps (1) to (4).

[0095] 1) A process for manufacturing a peroxytitanic acid solution containing tin and transition metal components from raw materials titanium compounds, tin compounds, transition metal compounds, alkaline substances, hydrogen peroxide and an aqueous dispersion medium.

[0096] (2) A process of heating the peroxytitanic acid solution containing tin and transition metal components produced in the above (1) process under pressure control and at 80 to 250°C to obtain a titanium oxide particle dispersion containing tin and transition metal components.

[0097] (3) A process of manufacturing a solution or a dispersion containing iron, titanium and silicon components from iron compounds, titanium compounds, silicon compounds and an aqueous dispersion medium.

[0098] (4) A process of mixing the titanium oxide particle dispersion produced in step (2) above with a solution or dispersion of iron compound, titanium compound and silicon compound produced in step (3) to obtain a dispersion.

[0099] Steps (1) and (2) are steps to obtain a titanium oxide particle dispersion containing a tin component and a transition metal component for improving visible light responsiveness. Step (3) is a step to obtain a solution containing an iron component, a titanium component, and a silicon component, or a dispersion containing an iron component, a titanium component, and a silicon component. Step (4) is a step to finally obtain a dispersion of titanium oxide particles containing a tin component and a transition metal component for improving visible light responsiveness, with the iron component, titanium component, and silicon component attached to the surface.

[0100] As described above, since at least one of molybdenum compound, tungsten compound and vanadium compound is preferably used as the transition metal compound in step (1), each step will be described in detail below based on this premise.

[0101] ■Process (1):

[0102] In step (1), a peroxytitanic acid solution containing tin and transition metal components is produced by reacting raw materials titanium compound, tin compound, transition metal compound, alkaline substance and hydrogen peroxide in an aqueous dispersion medium.

[0103] The reaction method can be any one of the methods described in i) to iii).

[0104] i) A method of forming titanium hydroxide containing tin and transition metal components by adding tin compound and transition metal compound to raw titanium compound and alkaline substance relative to aqueous dispersion medium and dissolving them, removing impurity ions other than metal ions, and adding hydrogen peroxide to form peroxytitanic acid containing tin and transition metal components.

[0105] ii) A method for forming titanium hydroxide hydrate by adding an alkaline substance to a raw titanium compound in an aqueous dispersion medium, removing impurity ions other than metal ions, adding tin compounds and transition metal compounds, and further adding hydrogen peroxide, thereby forming peroxytitanic acid containing tin and transition metal components.

[0106] iii) A method for adding an alkaline substance to a raw titanium compound in an aqueous dispersion medium to form titanium hydroxide, removing impurity ions other than metal ions, adding hydrogen peroxide to form peroxytitanic acid, and then adding tin compounds and transition metal compounds to obtain peroxytitanic acid containing tin and transition metal components.

[0107] It should be noted that in the first part of method i), the "raw material titanium compound and alkaline substance in aqueous dispersion medium" can also be divided into two types of aqueous dispersion mediums, such as "aqueous dispersion medium in which the raw material titanium compound has been dispersed" and "aqueous dispersion medium in which the alkaline substance has been dispersed". Based on the solubility of the tin compound and the transition metal compound in the two liquids, the respective compounds are dissolved in one or both of the two liquids and then the two are mixed.

[0108] Thus, after obtaining peroxytitanic acid containing tin and transition metal components, titanium oxide ions containing various metals dissolved in titanium oxide can be obtained by performing a hydrothermal reaction in step (2) described later.

[0109] Examples of titanium compounds used as raw materials include, for instance, inorganic acid salts such as titanium chloride, titanium nitrate, and titanium sulfate; organic acid salts such as titanium formic acid, titanium citric acid, titanium oxalic acid, titanium lactic acid, and titanium glycolic acid; and titanium hydroxide precipitated by hydrolysis with the addition of alkali to these aqueous solutions. One or more of these compounds may be used. Among these, titanium chlorides (TiCl3, TiCl4) are preferred.

[0110] The compounds described above are used as tin compounds, transition metal compounds, and aqueous dispersion media, respectively, according to the formulations described above. It should be noted that the concentration of the aqueous solution of the raw titanium compound formed from the raw titanium compound and the aqueous dispersion media is preferably 60% by mass or less, particularly preferably 30% by mass or less. A lower limit of the concentration can be appropriately selected, and it is generally preferred to be 1% by mass or more.

[0111] The alkaline substance is used to facilitate the formation of titanium hydroxide from the raw titanium compound. Examples include hydroxides of alkali metals or alkaline earth metals such as sodium hydroxide and potassium hydroxide; and amine compounds such as ammonia, alkanolamines, and alkylamines. Ammonia is particularly preferred, and it is added in an amount that brings the pH of the aqueous solution of the raw titanium compound to 7 or higher, particularly to a pH of 7 to 10. It should be noted that the alkaline substance can also be used to form an aqueous solution of appropriate concentration together with the aforementioned aqueous dispersion medium.

[0112] Hydrogen peroxide is used to convert the aforementioned raw titanium compounds or titanium hydroxide into peroxytitanic acid, that is, into titanium oxide compounds containing Ti-OO-Ti bonds, and is usually used in the form of hydrogen peroxide. The amount of hydrogen peroxide added is preferably 1.5 to 20 moles of the total molar amounts of Ti, transition metals, and Sn. Furthermore, in the reaction of adding hydrogen peroxide to form peroxytitanic acid from the raw titanium compounds or titanium hydroxide, the reaction temperature is preferably 5 to 80°C, and the reaction time is preferably 30 minutes to 24 hours.

[0113] The resulting peroxytitanic acid solution containing tin and transition metal components can also contain alkaline or acidic substances to adjust the pH. Examples of alkaline substances include ammonia, sodium hydroxide, calcium hydroxide, and alkylamines; examples of acidic substances include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, carbonic acid, phosphoric acid, and hydrogen peroxide, and organic acids such as formic acid, citric acid, oxalic acid, lactic acid, and glycolic acid. In this case, from the viewpoint of operational safety, the pH of the resulting peroxytitanic acid solution containing tin and transition metal components is preferably 1 to 9, and particularly preferably 4 to 7.

[0114] • Process (2):

[0115] In step (2), under pressure control and at a temperature of 80–250°C, preferably 100–250°C, a hydrothermal reaction is carried out on the peroxytitanic acid solution containing tin and transition metal components obtained in step (1) for 0.01–24 hours. From the viewpoint of reaction efficiency and controllability, the reaction temperature is preferably 80–250°C. As a result, the peroxytitanic acid containing tin and transition metal components is converted into titanium oxide particles with tin and transition metal components dissolved in solid solution. It should be noted that "under pressure control" here means that when the reaction temperature exceeds the boiling point of the dispersion medium, appropriate pressure is applied in a manner that can maintain the reaction temperature, thereby maintaining the reaction temperature. It also includes cases where atmospheric pressure is used when the temperature is set below the boiling point of the dispersion medium. The pressure used here is typically about 0.12–4.5 MPa, preferably about 0.15–4.5 MPa, and more preferably about 0.20–4.5 MPa. The reaction time is preferably 1 minute to 24 hours. Through this process (2), a dispersion of titanium oxide particles containing tin and transition metal components is obtained.

[0116] The pH of the titanium dioxide particle dispersion containing tin and transition metal components obtained in step (2) is preferably 8 to 14, more preferably 10 to 14. The titanium dioxide particle dispersion containing tin and transition metal components obtained in step (2) may also contain alkaline or acidic substances for pH adjustment in a manner that achieves the stated pH. The alkaline substances, acidic substances, and pH adjustment methods are the same as those used for the peroxytitanic acid solution obtained in step (1).

[0117] The particle size (D) of the titanium dioxide particles obtained here 50 and D 90 The preferred range is as described above. The particle size can also be controlled by adjusting the reaction conditions. For example, the particle size can be reduced by shortening the reaction time and heating time.

[0118] • Process (3):

[0119] In step (3), unlike steps (1) to (2) above, a solution or dispersion containing iron, titanium and silicon is produced by dissolving or dispersing the raw iron compound, raw titanium compound and raw silicon compound in an aqueous dispersion medium.

[0120] Iron compounds that can be used as raw materials include the aforementioned iron compounds, such as elemental iron (Fe), iron oxides (Fe₂O₃, Fe₃O₄), iron hydroxides (Fe(OH)₂, Fe(OH)₃), iron hydroxyoxides (FeO(OH)), iron chlorides (FeCl₂, FeCl₃), iron nitrates (Fe(NO)₃), iron sulfates (FeSO₄, Fe₂(SO₄)₃), iron halides (Br, I) other than chlorides, and iron complexes. One or more of these compounds can be used. Iron oxides (Fe₂O₃, Fe₃O₄), iron hydroxyoxides (FeO(OH)), iron chlorides (FeCl₂, FeCl₃), iron nitrates (Fe(NO)₃), and iron sulfates (FeSO₄, Fe₂(SO₄)₃) are preferred.

[0121] Examples of titanium compounds that can be used as raw materials include the aforementioned titanium compounds, such as elemental titanium (Ti), titanium hydroxide (Ti(OH)4), titanium hydroxyoxide (TiO(OH)2), titanium chloride (TiCl4, TiCl3, TiCl2), titanium nitrate (Ti(NO)4), titanium sulfate (Ti(SO4)2, TiOSO4), halogen (Br, I) compounds other than titanium chloride, titanium complexes, and titanium peroxide compounds (titanium oxide compounds containing Ti-OO-Ti bonds). One or more of these compounds can be used. Preferably, titanium hydroxide (Ti(OH)4), titanium hydroxyoxide (TiO(OH)2), titanium chloride (TiCl4, TiCl3, TiCl2), titanium nitrate (Ti(NO)4), titanium sulfate (Ti(SO4)2, TiOSO4), and titanium peroxide compounds (titanium oxide compounds containing Ti-OO-Ti bonds) are used.

[0122] Examples of silicon compounds that can be used as raw material include, for example, elemental silicon (Si), silicon oxides (SiO, SiO2), silicon alkoxides (Si(OCH3)4, Si(OC2H5)4, Si(OCH(CH3)2)4), silicates (sodium salts, potassium salts), and active silicic acid obtained by removing sodium or potassium ions from such silicates. One of these compounds or a combination of two or more of them can be used. Among these, silicates (sodium silicate) or active silicic acid are preferred. Active silicic acid is obtained, for example, by adding a cation exchange resin to an aqueous solution of sodium silicate in which sodium silicate has been dissolved in pure water, and removing at least some of the sodium ions. The resulting active silicic acid solution has a pH of 2 to 10, preferably with the cation exchange resin added at a pH of 2 to 7.

[0123] The resulting solution or dispersion containing iron, titanium, and silicon may contain alkaline or acidic substances for pH adjustment. The alkaline and acidic substances, as well as pH adjustment, can be processed in the same manner as described above. The pH of the solution or dispersion containing iron, titanium, and silicon is preferably 1 to 7, more preferably 1 to 5.

[0124] The concentration of the raw material iron compound in the solution or dispersion containing iron, titanium and silicon components manufactured in step (3) is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass; the concentration of the raw material titanium compound is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass; and the concentration of the raw material silicon compound is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass.

[0125] • Process (4):

[0126] In step (4), the titanium oxide particle dispersion obtained in step (2) and the solution or dispersion containing iron, titanium and silicon obtained in step (3) are mixed. There are no particular limitations on the mixing method; it can be a stirring method using a mixer or a dispersion method using an ultrasonic disperser. The mixing temperature is 20–100°C, preferably 20–80°C, more preferably 20–40°C, and the mixing time is preferably 1 minute to 3 hours. Regarding the mixing ratio, the molar ratio of TiO2 to Fe, Ti and Si in the titanium oxide particle dispersion can be mixed in the molar ratio described above.

[0127] The titanium dioxide particle dispersion obtained in the above steps (1) to (4) may contain alkaline or acidic substances to adjust the pH, etc. The aforementioned substances can be used as pH adjusters. In addition, ion exchange treatment or filtration and cleaning treatment can be performed to adjust the concentration of ionic components, or solvent replacement treatment can be performed to change the solvent composition. The pH of the titanium dioxide particle dispersion is preferably 7 to 14, more preferably 8 to 12.

[0128] The mass of titanium oxide particles contained in the titanium oxide particle dispersion can be calculated from the mass and concentration of the titanium oxide particle dispersion. It should be noted that the concentration of the titanium oxide particle dispersion can be determined by taking a sample of the titanium oxide particle dispersion, heating it at 105°C for 1 hour to allow the solvent to evaporate, and then calculating the mass of the non-volatile component (titanium oxide particles) and the mass of the sampled titanium oxide particle dispersion using the following formula.

[0129] Concentration (%) of titanium dioxide particle dispersion = (mass of non-volatile components (g) / mass of titanium dioxide particle dispersion (g)) × 100

[0130] As described above, from the viewpoint of ease of preparing a photocatalyst film of the desired thickness, the total concentration of iron, titanium, silicon, and titanium oxide particles in the prepared titanium oxide particle dispersion is preferably 0.01–20% by mass, and particularly preferably 0.5–10% by mass. Regarding concentration adjustment, if the concentration is higher than desired, it can be reduced by adding an aqueous solvent for dilution. If the concentration is lower than desired, it can be increased by evaporating or filtering the aqueous solvent. Alternatively, the concentration can be calculated as described above.

[0131] In addition, when adding the above-mentioned adhesive for improving film-forming properties, it is preferable to add the solution of the above-mentioned adhesive (aqueous adhesive solution) to the titanium dioxide particle dispersion that has been adjusted in concentration as described above, so as to achieve the desired concentration after mixing.

[0132] It should be noted that the silicon component in the titanium dioxide particle dispersion is used to inhibit the aggregation and precipitation of titanium dioxide particles, iron, and titanium components, thereby suppressing the reduction of photocatalytic activity. It is added simultaneously when mixing the titanium dioxide particles, iron, and titanium components. On the other hand, the binder is used to improve the film-forming properties of the titanium dioxide particle dispersion. It is added after the preparation of the titanium dioxide particle dispersion and before coating; the two are different components.

[0133] <Titanium oxide particles>

[0134] The titanium dioxide particles of the present invention are characterized by having a tin component and a transition metal for improving visible light activity dissolved in solid solution, and having an iron component, a titanium component, and a silicon component attached to their surface. The iron, titanium, and silicon components may be attached to at least a portion of the surface of the titanium dioxide particles, or they may be attached to the entire surface of the titanium dioxide particles.

[0135] There are no particular limitations on the method for adhering the iron, titanium, and silicon components to the surface of the titanium oxide particles. Examples include mixing in a solid state (mixing titanium oxide particle powder with a powder composed of iron, titanium, and silicon), mixing in a liquid state (mixing a titanium oxide particle dispersion with a solution or dispersion composed of iron, titanium, and silicon), and mixing a solid and a liquid (mixing a solution or dispersion composed of iron, titanium, and silicon into titanium oxide particle powder, or mixing a powder composed of iron, titanium, and silicon into a titanium oxide particle dispersion). Since silicon plays a role in inhibiting the aggregation of iron and titanium, it is preferable to mix the iron, titanium, and silicon components with the titanium oxide particles after pre-mixing them.

[0136] Alternatively, the iron and titanium components can be mixed separately. Specifically, the iron and silicon components can be mixed into the titanium oxide particles first, and then the titanium and silicon components can be mixed in, or vice versa, the titanium and silicon components can be mixed into the titanium oxide particles first, and then the iron and silicon components can be mixed in. The above methods can be cited as examples of mixing methods.

[0137] The preferred method is to mix the particles in a liquid state, and the more preferred method is to follow the steps (1) to (4) as described above in the method for manufacturing titanium dioxide particle dispersion.

[0138] It is sufficient to attach at least a portion of the mixed iron, titanium, and silicon components to the surface of the titanium oxide particles; alternatively, all of the mixed iron, titanium, and silicon components can be attached to the surface of the titanium oxide particles. Furthermore, the iron, titanium, and silicon components can also be directly attached to the surface of each individual titanium oxide particle.

[0139] <Photocatalyst film containing titanium oxide particles ■ Component with a photocatalyst film on its surface>

[0140] To form a photocatalytic film on the surface of various components, the titanium dioxide particle dispersion of the present invention can be used. There are no particular limitations on the various components; the materials used as components can include organic and inorganic materials. These can have various shapes depending on their respective purposes and uses.

[0141] Examples of organic materials include: polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polycarbonate (PC), acrylic resin, polyacetal, fluoropolymer, silicone resin, ethylene-vinyl acetate copolymer (EVA), nitrile rubber (NBR), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyvinyl butyral (PVB), ethylene-vinyl alcohol copolymer (EVOH), polyimide resin, polyphenylene sulfide (PPS), polyetherimide (PEI), polyetheretherimide (PEEI), polyetheretherketone (PEEK), melamine resin, phenolic resin, acrylonitrile-butadiene-styrene (ABS) resin, and other synthetic resin materials; natural materials such as natural rubber; and semi-synthetic materials combining the above synthetic resin materials and natural materials. These materials can also be processed into films, sheets, other molded articles, laminates, and other desired shapes and compositions.

[0142] As inorganic materials, including, for example, non-metallic inorganic materials and metallic inorganic materials.

[0143] Examples of non-metallic inorganic materials include glass, ceramics, and stone. They can also be processed into various forms such as tiles, glass, mirrors, wall coverings, and design materials. Examples of metallic inorganic materials include cast iron, steel, iron, ferroalloys, aluminum, aluminum alloys, nickel, nickel alloys, and zinc die castings. These can be plated with the aforementioned metallic inorganic materials, coated with the aforementioned organic materials, or plated on the surface of the aforementioned organic or non-metallic inorganic materials.

[0144] The titanium dioxide particle dispersion of the present invention is particularly useful for preparing photocatalyst films on various components made of inorganic materials such as glass and metal, as well as organic materials such as resin, and is particularly useful for preparing transparent photocatalyst films on various components.

[0145] One method for forming a photocatalyst film on the surface of various components is, for example, coating a titanium oxide particle dispersion onto the surface of the component using a known coating method such as spraying or dip coating, followed by drying using a known drying method such as far-infrared drying, IH drying, or hot air drying. The thickness of the photocatalyst film can be selected in various ways, but is generally preferred to be in the range of 10 nm to 10 μm.

[0146] Thus, a film of titanium dioxide particles is formed. At this time, if the dispersion contains a binder in the aforementioned amount, a film containing titanium dioxide particles and a binder can be formed.

[0147] The resulting photocatalytic film is transparent and exhibits excellent photocatalytic activity not only in the ultraviolet region (wavelength 10–400 nm) as in conventional photocatalysts, but also in the visible light region (wavelength 400–800 nm), where conventional photocatalysts do not provide sufficient photocatalytic activity. Since the photocatalytic action of titanium dioxide can more rapidly degrade organic matter adsorbed on the surface, the various components forming this photocatalytic film can perform cleaning, deodorizing, and antibacterial effects on the surface of the component.

[0148] Example

[0149] The following examples and comparative examples are shown to specifically illustrate the present invention, but the present invention is not limited to the following examples. Various measurements in the present invention are performed as described below.

[0150] (1) The 50% and 90% cumulative distribution diameters (D) of titanium oxide particles in the dispersion 50 and D 90 )

[0151] Using a particle size distribution measuring device (ELSZ-2000ZS (manufactured by Otsuka Electronics Co., Ltd., Japan)), the D of titanium oxide particles in the dispersion was calculated in the form of the 50% and 90% cumulative distribution diameters based on the volume standard, measured by laser dynamic light scattering. 50 and D 90 .

[0152] (2) Test on the acetaldehyde gas degradation performance of the photocatalyst film

[0153] The activity of a photocatalyst film prepared from a coated and dried dispersion was evaluated by the degradation reaction of acetaldehyde gas. The evaluation was conducted using a batch gas degradation performance evaluation method.

[0154] Using a #7 wire bar coater, the titanium dioxide particle dispersions prepared in the examples or comparative examples were spread and coated on one side of an A4-sized (210mm × 297mm) PET film with a dry titanium dioxide particle mass of approximately 20mg to prepare evaluation samples. The samples were then dried in an oven set to 80°C for 1 hour to obtain acetaldehyde gas degradation performance evaluation samples.

[0155] Using the evaluation sample, the photocatalytic activity of titanium dioxide particles was evaluated through the degradation reaction with acetaldehyde gas. The evaluation was conducted using a batch gas degradation performance evaluation method.

[0156] Specifically, after placing the evaluation sample in a 5L stainless steel unit with a quartz glass window, the unit was filled with acetaldehyde gas at an initial concentration humidified to 50%, and illuminated by a light source positioned above the unit. When the acetaldehyde gas was degraded by the photocatalytic action of titanium dioxide, the acetaldehyde gas concentration in the unit decreased. The intensity of the photocatalyst activity was confirmed by measuring this concentration change. The acetaldehyde gas concentration was measured using a photoacoustic multi-gas monitor (trade name "INNOVA1412", manufactured by LumaSense), and the time required for the acetaldehyde gas concentration to decrease to 1 ppm from the start of light irradiation was also measured to evaluate the photocatalyst activity. A shorter time indicated higher photocatalyst activity, while a longer time indicated lower photocatalyst activity.

[0157] In the evaluation of photocatalytic activity under visible light irradiation, an LED (commercial model "TH-211×200SW", CCS Inc, spectral distribution: 400~800nm) was used as the light source, and visible light was irradiated under an illuminance of 10000Lx. At this time, the initial concentration of acetaldehyde in the unit was 5ppm.

[0158] In addition, in the evaluation of photocatalytic activity under ultraviolet irradiation, a UV fluorescent lamp (commercial model "FL10BLB", TOSHIBA LIGHTING & TECHNOLOGY CORPORATION) was used as the light source at an irradiance of 0.2 mW / cm². 2 Under these conditions, the unit was irradiated with ultraviolet light (352 nm). At this time, the initial concentration of acetaldehyde in the unit was 20 ppm.

[0159] (3) Identification of the crystal phase of titanium oxide particles

[0160] The crystal phase of the titanium oxide particles was identified by powder X-ray diffraction (trade name "D2PHASER benchtop X-ray diffractometer", Bruker AXS Ltd.) of the recovered titanium oxide particle powder obtained by drying the dispersion of the titanium oxide particles at 105°C for 3 hours.

[0161] (4) Preparation of titanium dioxide particle dispersion

[0162] [Preparation Example 1-1]

[0163] <Preparation of titanium dioxide particle dispersions with dissolved tin and molybdenum>

[0164] By adding tin(IV) chloride to a 36% by mass aqueous solution of titanium(IV) chloride and dissolving it, the TiO2 / Sn (molar ratio) in the titanium oxide particle dispersion obtained in Preparation Example 1-1 was made 20. After diluting it 10 times with pure water, 10% by mass ammonia was slowly added for neutralization and hydrolysis, thus obtaining a tin-containing titanium hydroxide precipitate. The pH at this time was 8. The obtained precipitate was repeatedly subjected to deionization treatment by adding pure water and decantation. Sodium molybdate (VI) was added to the tin-containing titanium hydroxide precipitate after deionization treatment, so that the TiO2 / Mo (molar ratio) in the titanium oxide particle dispersion obtained in Preparation Example 1-1 was 400. By adding 35% by mass hydrogen peroxide, the H2O2 / (Ti+Sn+Mo) (molar ratio) was made 10, and then the mixture was stirred at 60°C for 2 hours to allow it to react fully, thus obtaining an orange transparent peroxytitanic acid solution containing tin and molybdenum (1a).

[0165] 400 mL of a peroxytitanic acid solution (1a) containing tin and molybdenum was added to a 500 mL autoclave, and the solution was subjected to hydrothermal treatment at 150 °C for 90 minutes. The concentration was then adjusted by adding pure water to obtain a dispersion of titanium oxide particles (1A) with dissolved tin and molybdenum (titanium oxide concentration 1.2 wt%). Powder X-ray diffraction analysis of the titanium oxide particles (1A) showed only rutile titanium oxide peaks, indicating that tin and molybdenum were dissolved in the titanium oxide.

[0166] [Preparation Examples 1-2]

[0167] Preparation of titanium dioxide particle dispersions with dissolved tin and tungsten

[0168] By adding tin(IV) chloride to a 36% by mass aqueous solution of titanium(IV) chloride and dissolving it, the TiO2 / Sn (molar ratio) in the titanium oxide particle dispersion obtained in Preparation Examples 1-2 was made 10. After diluting it 10 times with pure water, 10% by mass ammonia was slowly added for neutralization and hydrolysis, thus obtaining a tin-containing titanium hydroxide precipitate. The pH at this time was 8. The obtained precipitate was repeatedly subjected to deionization treatment by adding pure water and decantation. Sodium tungstate (VI) was added to the tin-containing titanium hydroxide precipitate after deionization treatment, so that the TiO2 / W (molar ratio) in the titanium oxide particle dispersion obtained in Preparation Examples 1-2 was made 100. By adding 35% by mass hydrogen peroxide, the H2O2 / (Ti+Sn+W) (molar ratio) was made 10, and then the mixture was stirred at 60°C for 2 hours to allow it to react fully, thus obtaining an orange transparent peroxytitanic acid solution containing tin and tungsten (1b).

[0169] 400 mL of a peroxytitanic acid solution (1b) containing tin and tungsten was added to a 500 mL autoclave, and the solution was subjected to hydrothermal treatment at 160 °C for 60 minutes. The concentration was then adjusted by adding pure water, resulting in a dispersion of titanium oxide particles (1B) with dissolved tin and tungsten (titanium oxide concentration 1.2% by mass). Powder X-ray diffraction analysis of the titanium oxide particles (1B) showed only rutile titanium oxide peaks, indicating that tin and tungsten were dissolved in the titanium oxide.

[0170] [Preparation Examples 1-3]

[0171] Preparation of titanium dioxide particle dispersions with dissolved tin and vanadium

[0172] By adding tin(IV) chloride to a 36% by mass aqueous solution of titanium(IV) chloride and dissolving it, the TiO2 / Sn (molar ratio) in the titanium oxide particle dispersion obtained in Preparation Examples 1-3 was made 33. After diluting it 10 times with pure water, 10% by mass ammonia was slowly added for neutralization and hydrolysis, thus obtaining a tin-containing titanium hydroxide precipitate. The pH at this time was 8. The obtained precipitate was repeatedly subjected to deionization treatment by adding pure water and decantation. Sodium vanadate (V) was added to the tin-containing titanium hydroxide precipitate after deionization treatment, so that the TiO2 / V (molar ratio) in the titanium oxide particle dispersion obtained in Preparation Examples 1-3 was 2000. By adding 35% by mass hydrogen peroxide, the H2O2 / (Ti+Sn+V) (molar ratio) was made 10, and then the mixture was stirred at 50°C for 3 hours to allow it to react fully, thus obtaining an orange transparent peroxytitanic acid solution containing tin and vanadium (1c).

[0173] 400 mL of a peroxytitanic acid solution (1c) containing tin and vanadium was added to a 500 mL autoclave, and the solution was subjected to hydrothermal treatment at 140 °C for 120 minutes. The concentration was then adjusted by adding pure water, resulting in a dispersion of titanium oxide particles (1C) with dissolved tin and vanadium (titanium oxide concentration 1.2% by mass). Powder X-ray diffraction analysis of the titanium oxide particles (1C) revealed peaks of both anatase and rutile titanium oxide, indicating that tin and vanadium were dissolved in the titanium oxide.

[0174] [Preparation Examples 1-4]

[0175] <Preparation of titanium dioxide particle dispersions with dissolved tin and molybdenum>

[0176] By adding tin(IV) chloride to a 36% by mass aqueous solution of titanium(IV) chloride and dissolving it, the TiO2 / Sn (molar ratio) in the titanium oxide particle dispersion obtained in Preparation Examples 1-4 was made 20. After diluting it 10 times with pure water, 10% by mass ammonia was slowly added for neutralization and hydrolysis, thus obtaining a tin-containing titanium hydroxide precipitate. The pH at this time was 8. The obtained precipitate was repeatedly subjected to deionization treatment by adding pure water and decantation. Sodium molybdate (VI) was added to the tin-containing titanium hydroxide precipitate after deionization treatment, so that the TiO2 / Mo (molar ratio) in the titanium oxide particle dispersion obtained in Preparation Examples 1-4 was 100. By adding 35% by mass hydrogen peroxide, the H2O2 / (Ti+Sn+Mo) (molar ratio) was made 12, and then the mixture was stirred at 60°C for 2 hours to allow it to react fully, thus obtaining an orange transparent peroxytitanic acid solution containing tin and molybdenum (1d).

[0177] 400 mL of a peroxytitanic acid solution (1d) containing tin and molybdenum was added to a 500 mL autoclave, and the solution was subjected to hydrothermal treatment at 120 °C for 180 minutes. The concentration was then adjusted by adding pure water to obtain a dispersion of titanium oxide particles (1D) with dissolved tin and molybdenum (titanium oxide concentration 1.2% by mass). Powder X-ray diffraction analysis of the titanium oxide particles (1D) showed only rutile titanium oxide peaks, indicating that tin and molybdenum were dissolved in the titanium oxide.

[0178] [Preparation Examples 1-5]

[0179] Preparation of titanium dioxide particle dispersions with dissolved tin, tungsten, and vanadium

[0180] By adding tin(IV) chloride to a 36% by mass aqueous solution of titanium(IV) chloride and dissolving it, the TiO2 / Sn (molar ratio) in the titanium oxide particle dispersion obtained in Preparation Examples 1-5 was made 50. After diluting it 10 times with pure water, 10% by mass ammonia was slowly added for neutralization and hydrolysis, thus obtaining a tin-containing titanium hydroxide precipitate. The pH at this time was 8. The obtained precipitate was repeatedly subjected to deionization treatment by adding pure water and decantation. Sodium tungstate (VI) was added to the tin-containing titanium hydroxide precipitate after deionization treatment, so that the TiO2 / W (molar ratio) in the titanium oxide particle dispersion obtained in Preparation Examples 1-5 was 33, and sodium vanadate (V) was added, so that the TiO2 / V (molar ratio) in the titanium oxide particle dispersion obtained in Preparation Examples 1-5 was 5000. By adding 35% hydrogen peroxide to make the H2O2 / (Ti+Sn+W) (molar ratio) 10, and then stirring at 60°C for 2 hours to allow the reaction to proceed fully, an orange transparent peroxytitanic acid solution containing tin, tungsten and vanadium was obtained (1e).

[0181] 400 mL of a peroxytitanic acid solution (1e) containing tin, tungsten, and vanadium was added to a 500 mL autoclave, and the solution was subjected to hydrothermal treatment at 140 °C for 120 minutes. The concentration was then adjusted by adding pure water to obtain a dispersion of titanium oxide particles (1E) with dissolved tin, tungsten, and vanadium (titanium oxide concentration 1.2 wt%). Powder X-ray diffraction analysis of the titanium oxide particles (1E) revealed peaks characteristic of anatase and rutile titanium oxide, indicating that tin, tungsten, and vanadium are dissolved in the titanium oxide.

[0182] [Preparation Examples 1-6]

[0183] Preparation of titanium dioxide particle dispersion with tin solution

[0184] Except for the absence of sodium molybdate (VI), the same method as in Preparation Example 1-1 was used to obtain a dispersion of titanium oxide particles (1F) with tin dissolved in it (titanium oxide concentration 1.2% by mass). When powder X-ray diffraction was performed on the titanium oxide particles (1F), only the peaks of rutile titanium oxide were observed, indicating that tin was dissolved in titanium oxide.

[0185] [Preparation Examples 1-7]

[0186] Preparation of titanium dioxide particle dispersion with molybdenum in solid solution

[0187] Except for the absence of tin chloride (IV), the same method as in Preparation Example 1-1 was used to obtain a dispersion of molybdenum-dissolved titanium oxide particles (1G) (titanium oxide concentration 1.2% by mass). When powder X-ray diffraction was performed on the titanium oxide particles (1G), only anatase titanium oxide peaks were observed, indicating that molybdenum was dissolved in titanium oxide.

[0188] [Preparation Examples 1-8]

[0189] Preparation of titanium dioxide particle dispersion with tungsten solution

[0190] Except for the absence of tin chloride (IV), the same method as in Preparation Examples 1-2 was used to obtain a dispersion of titanium oxide particles (1H) with tungsten dissolved in it (titanium oxide concentration 1.2% by mass). When powder X-ray diffraction was performed on the titanium oxide particles (1H), only anatase titanium oxide peaks were observed, indicating that tungsten was dissolved in the titanium oxide.

[0191] [Preparation Examples 1-9]

[0192] Preparation of titanium dioxide particle dispersion with vanadium solution

[0193] Except for the absence of tin chloride (IV), the same method as in Preparation Examples 1-3 was used to obtain a dispersion of titanium oxide particles (I) with vanadium dissolved in it (titanium oxide concentration 1.2% by mass). When the titanium oxide particles (I) were subjected to powder X-ray diffraction, only the peaks of anatase titanium oxide were observed, indicating that vanadium was dissolved in titanium oxide.

[0194] The molar ratio, hydrothermal treatment conditions, and dispersion particle size (D) of the titanium oxide particles prepared in each preparation example will be specified. 50 D 90 The pH values ​​of the titanium dioxide particle dispersions after hydrothermal treatment are summarized in Table 1. The particle size was determined using a laser dynamic light scattering method (ELSZ-2000ZS (manufactured by Otsuka Electronics Co., Ltd., Japan)).

[0195] [Table 1]

[0196]

[0197] (5) Preparation of solutions or dispersions containing iron, titanium and silicon.

[0198] [Preparation Example 2-1]

[0199] Preparation of aqueous solutions of ferric sulfate, titanium chloride and active silicic acid

[0200] A sodium silicate aqueous solution was prepared by dissolving 0.34 g of JIS No. 3 sodium silicate (29.1% by mass as SiO2) in 100 g of pure water. A strongly acidic cation exchange resin (Amberjet 1024H, manufactured by ORGANO CORPORATION) was added, and the solution was stirred. The ion exchange resin was then filtered off to obtain an aqueous solution of activated silicic acid. By adding 0.13 g of ferric sulfate (III) and 0.12 g of titanium chloride (IV) to this aqueous solution of activated silicic acid, an aqueous solution (2A) containing ferric sulfate, titanium chloride, and activated silicic acid with a pH of 1.8 was obtained.

[0201] [Preparation Example 2-2]

[0202] Preparation of aqueous solutions containing ferric sulfate, titanium chloride, and active silicic acid

[0203] A sodium silicate aqueous solution was prepared by dissolving 3.43 g of JIS No. 3 sodium silicate (29.1% by mass as SiO2) in 100 g of pure water. A strongly acidic cation exchange resin (Amberjet 1024H, manufactured by ORGANO CORPORATION) was added, and the solution was stirred. The ion exchange resin was then filtered off to obtain an aqueous solution of activated silicic acid. By adding 0.38 g of ferric sulfate (III) and 0.02 g of titanium chloride (IV) to this aqueous solution of activated silicic acid, an aqueous solution (2B) containing ferric sulfate, titanium chloride, and activated silicic acid with a pH of 2.2 was obtained.

[0204] [Preparation Examples 2-3]

[0205] Preparation of aqueous solutions containing ferric sulfate, titanium chloride, and active silicic acid

[0206] A sodium silicate aqueous solution was prepared by dissolving 0.17 g of JIS No. 3 sodium silicate (29.1% by mass as SiO2) in 100 g of pure water. A strongly acidic cation exchange resin (Amberjet 1024H, manufactured by ORGANO CORPORATION) was added, and the solution was stirred. The ion exchange resin was then filtered off to obtain an aqueous solution of activated silicic acid. By adding 0.06 g of ferric sulfate (III) and 0.06 g of titanium chloride (IV) to this aqueous solution of activated silicic acid, an aqueous solution (2C) containing ferric sulfate, titanium chloride, and activated silicic acid with a pH of 2.2 was obtained.

[0207] [Preparation Examples 2-4]

[0208] Preparation of aqueous solutions containing ferric sulfate and active silicic acid

[0209] Except for the absence of titanium chloride (IV), the same method as in Preparation Examples 2-3 was used to obtain an aqueous solution (2D) containing ferric sulfate and active silicic acid with a pH of 2.6.

[0210] [Preparation Examples 2-5]

[0211] Preparation of aqueous solutions containing titanium chloride and active silicic acid

[0212] Except for the absence of ferric sulfate (III), the same method as in Preparation Examples 2-3 was used to obtain an aqueous solution (2E) containing titanium chloride and active silicic acid with a pH of 2.2.

[0213] [Preparation Examples 2-6]

[0214] Preparation of ferric sulfate aqueous solution

[0215] Except for the absence of JIS No. 3 sodium silicate and titanium chloride (IV), the same method as in Preparation Example 2-2 was used to obtain an aqueous solution of ferric sulfate (2F) with a pH of 2.5.

[0216] [Preparation Examples 2-7]

[0217] <Preparation of Titanium Chloride Aqueous Solution>

[0218] Except for the absence of JIS No. 3 sodium silicate and ferric sulfate (III), the same method as in Preparation Example 2-1 was used to obtain an aqueous solution of titanium chloride (2G) with a pH of 1.8.

[0219] [Preparation Examples 2-8]

[0220] <Preparation of Active Silicic Acid Aqueous Solution>

[0221] Except for the absence of ferric sulfate and titanium chloride, the same method as in Preparation Example 2-1 was used to obtain an aqueous solution of active silicic acid (2H) with a pH of 4.8.

[0222] (6) Preparation of titanium dioxide particle dispersion

[0223] [Example 1]

[0224] An aqueous solution (2A) containing ferric sulfate, titanium chloride and active silicic acid was added to a dispersion of titanium oxide particles (1A) to make TiO2 / Fe 400, TiO2 / Ti 200 and TiO2 / Si 75. After mixing for 10 minutes at 25°C using a stirrer, the concentration of the solid components was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (E-1).

[0225] [Example 2]

[0226] An aqueous solution (2B) containing ferric sulfate, titanium chloride and active silicic acid was added to a dispersion of titanium oxide particles (1B) to make TiO2 / Fe 133, TiO2 / Ti 1000 and TiO2 / Si 8. After mixing for 10 minutes at 25°C using a stirrer, the concentration of the solid components was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (E-2).

[0227] [Example 3]

[0228] An aqueous solution (2C) containing ferric sulfate, titanium chloride, and active silicic acid was added to a dispersion of titanium oxide particles (1C) to achieve a TiO2 / Fe ratio of 800, a TiO2 / Ti ratio of 400, and a TiO2 / Si ratio of 150. After mixing for 10 minutes at 25°C using a stirrer, the concentration of the solid components was adjusted to 1% by mass with pure water, thus obtaining a titanium oxide particle dispersion (E-3).

[0229] [Example 4]

[0230] An aqueous solution (2A) containing ferric sulfate, titanium chloride and active silicic acid was added to a dispersion of titanium oxide particles (1D) to make TiO2 / Fe 400, TiO2 / Ti 200 and TiO2 / Si 75. After mixing for 10 minutes at 25°C using a stirrer, the concentration of the solid components was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (E-4).

[0231] [Example 5]

[0232] An aqueous solution (2A) containing ferric sulfate, titanium chloride and active silicic acid was added to a dispersion of titanium oxide particles (1E) to make TiO2 / Fe 400, TiO2 / Ti 200 and TiO2 / Si 75. After mixing for 10 minutes at 25°C using a stirrer, the concentration of the solid components was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (E-5).

[0233] [Example 6]

[0234] A binder (colloidal silica, trade name: SNOWTEX 20, manufactured by Nissan Chemical Industries, Ltd., Japan) of silicon compound (silica-based) was added to the titanium oxide particle dispersion (E-4) to make the TiO2 / SiO2 (mass ratio) 1.5. The titanium oxide particle dispersion containing the binder was obtained by mixing with a stirrer at 25°C for 10 minutes.

[0235] [Comparative Example 1]

[0236] An aqueous solution (2A) containing ferric sulfate, titanium chloride and active silicic acid was added to a dispersion of titanium oxide particles (1F) to make TiO2 / Fe 400, TiO2 / Ti 200 and TiO2 / Si 75. After mixing for 10 minutes at 25°C using a stirrer, the concentration of the solid components was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (C-1).

[0237] [Comparative Example 2]

[0238] An aqueous solution (2A) containing ferric sulfate, titanium chloride and active silicic acid was added to a dispersion of titanium oxide particles (1G) to make TiO2 / Fe 400, TiO2 / Ti 200 and TiO2 / Si 75. After mixing for 10 minutes at 25°C using a stirrer, the concentration of the solid components was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (C-2).

[0239] [Comparative Example 3]

[0240] An aqueous solution (2A) containing ferric sulfate, titanium chloride and active silicic acid was added to a dispersion of titanium oxide particles (1H) to make TiO2 / Fe 400, TiO2 / Ti 200 and TiO2 / Si 75. After mixing with a stirrer at 25°C for 10 minutes, the concentration of solid components was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (C-3).

[0241] [Comparative Example 4]

[0242] An aqueous solution (2A) containing ferric sulfate, titanium chloride and active silicic acid was added to a dispersion of titanium oxide particles (1I) to make TiO2 / Fe 400, TiO2 / Ti 200 and TiO2 / Si 75. After mixing for 10 minutes at 25°C using a stirrer, the concentration of the solid components was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (C-4).

[0243] [Comparative Example 5]

[0244] An aqueous solution (2D) containing ferric sulfate and active silicic acid was added to a dispersion of titanium oxide particles (1D) to make the TiO2 / Fe ratio 800 and the TiO2 / Si ratio 150. After mixing for 10 minutes at 25°C using a stirrer, the concentration of the solid components was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (C-5).

[0245] [Comparative Example 6]

[0246] An aqueous solution (2E) containing titanium chloride and active silicic acid was added to a dispersion of titanium oxide particles (1D) to make the TiO2 / Ti ratio 400 and the TiO2 / Si ratio 150. After mixing for 10 minutes at 25°C using a stirrer, the concentration of the solid components was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (C-6).

[0247] [Comparative Example 7]

[0248] An aqueous solution of ferric sulfate (2F) was added to the dispersion of titanium oxide particles (1D) to make the TiO2 / Fe ratio 133. After mixing with a stirrer at 25°C for 10 minutes, the concentration of the solid component was adjusted to 1% by mass with pure water, thus obtaining the titanium oxide particle dispersion (C-7).

[0249] By adding ferric sulfate, the titanium oxide particles aggregated, and some precipitated, resulting in a cloudy appearance of the dispersion. Furthermore, when the titanium oxide particle dispersion (C-7) was filtered through a 1μm PP filter, brown iron components were filtered out, indicating that iron also aggregated.

[0250] [Comparative Example 8]

[0251] An aqueous solution of titanium chloride (2G) was added to a dispersion of titanium oxide particles (1D) to make the TiO2 / Ti ratio 200. After mixing for 10 minutes at 25°C using a stirrer, the concentration of the solid component was adjusted to 1% by mass with pure water to obtain a titanium oxide particle dispersion (C-8).

[0252] By adding titanium chloride, the titanium oxide particles aggregated, and some of them precipitated, resulting in a cloudy white appearance of the dispersion. Furthermore, when the titanium oxide particle dispersion (C-8) was filtered through a 1μm PP filter, a white aqueous component was filtered out, indicating that in addition to the aggregation of titanium oxide, the titanium component also aggregated.

[0253] [Comparative Example 9]

[0254] An aqueous solution of active silicic acid (2H) was added to the dispersion of titanium oxide particles (1D) to make the TiO2 / Si ratio 75. After mixing with a stirrer at 25°C for 10 minutes, the concentration of the solid component was adjusted to 1% by mass with pure water, thus obtaining the titanium oxide particle dispersion (C-9).

[0255] [Comparative Example 10]

[0256] The concentration of the solid component in the dispersion of titanium oxide particles (1D) was adjusted to 1% by mass using pure water, thus obtaining the titanium oxide particle dispersion (C-10).

[0257] [Comparative Example 11]

[0258] A binder (colloidal silica, trade name: SNOWTEX 20, manufactured by Nissan Chemical Industries, Ltd., Japan) of silicon compound (silica-based) was added to the titanium oxide particle dispersion (C-5) to make the TiO2 / SiO2 (mass ratio) 1.5. The titanium oxide particle dispersion containing the binder was obtained by mixing with a stirrer at 25°C for 10 minutes.

[0259] [Comparative Example 12]

[0260] A binder (colloidal silica, trade name: SNOWTEX 20, manufactured by Nissan Chemical Industries, Ltd., Japan) of silicon compound (silica-based) was added to the titanium oxide particle dispersion (C-6) to make the TiO2 / SiO2 (mass ratio) 1.5. The titanium oxide particle dispersion (C-12) containing the binder was obtained by mixing with a stirrer at 25°C for 10 minutes.

[0261] (7) Preparation of sample components with photocatalyst thin films

[0262] Using a wire bar coater (#7), the titanium dioxide particle dispersions prepared in the above examples or comparative examples were coated onto A4-sized PET films to form photocatalyst films (approximately 80 nm thick) containing 20 mg of photocatalyst titanium dioxide particles. The films were then dried in an oven set to 80°C for 1 hour to obtain sample components for evaluating the acetaldehyde gas degradation performance.

[0263] [Photocatalytic performance test under visible light irradiation]

[0264] Acetaldehyde degradation tests were conducted on sample components of the photocatalyst films from the examples and comparative examples under visible light irradiation by LEDs. The photocatalytic performance was evaluated based on the time required for the acetaldehyde concentration to decrease from an initial concentration of 5 ppm to 1 ppm.

[0265] It should be noted that if the initial acetaldehyde concentration cannot be reduced to 1 ppm within 24 hours, in Tables 2 and 3, "time required to degrade to 1 ppm" will be indicated as "-", and "concentration after 24 hours" will be indicated as the concentration after 24 hours.

[0266] The types of titanium oxide particles and added metal components in Examples 1-5 and Comparative Examples 1-10, the molar ratio of the metals in the added metal components relative to titanium oxide (TiO2), and the dispersion particle size (D) were compared. 50 D 90 The results of the pH and acetaldehyde gas degradation tests under visible light irradiation are summarized in Table 2. The dispersed particle size was determined using the laser dynamic light scattering method (ELSZ-2000ZS (manufactured by Otsuka Electronics Co., Ltd., Japan)).

[0267] [Table 2]

[0268]

[0269] Based on the results of Examples 1-5 and Comparative Examples 1-4, it can be seen that, compared with the case of using titanium oxide particles containing both a tin component and a transition metal component for improving visible light activity, or the case of using titanium oxide in which neither the tin component nor the transition metal component is in solution, the photocatalytic activity under visible light irradiation is high.

[0270] The results of Examples 4 and Comparative Examples 5, 6, 9, and 10 show that, compared with photocatalytic titanium oxide with iron and silicon components (2D), titanium and silicon components (2E), and silicon components (2H) attached to the surface of titanium oxide particles (1D), and compared with photocatalytic titanium oxide with no components attached to the surface of titanium oxide particles (1D), photocatalytic titanium oxide with iron, titanium, and silicon components (2A) attached to the surface of titanium oxide particles (1D) exhibits higher photocatalytic activity under visible light irradiation.

[0271] The results of Examples 4 and Comparative Examples 7 and 8 show that by adding silicon to titanium oxide particles (1D) along with iron and titanium, the aggregation and precipitation of titanium oxide particles, iron and titanium can be suppressed.

[0272] As can be confirmed from the above, the titanium dioxide particles of the present invention, which have iron, titanium and silicon components attached to their surface and tin and transition metal components for improving visible light activity, exhibit excellent photocatalytic performance.

[0273] [Photocatalytic performance test under UV irradiation]

[0274] Acetaldehyde degradation tests were conducted on the sample components with photocatalyst films from Examples 6, 11, and 12 under UV fluorescent lamp irradiation. The photocatalytic performance was evaluated based on the time required for the acetaldehyde concentration to decrease from an initial 20 ppm to 1 ppm.

[0275] The types of titanium oxide particles and added metal components, the molar ratio of the added metal components to titanium oxide (TiO2), and the dispersion particle size (D) are considered. 50 D 90 The results of the pH and acetaldehyde gas degradation tests are summarized in Table 3. The dispersed particle size was determined using the laser dynamic light scattering method (ELSZ-2000ZS (manufactured by Otsuka Electronics Co., Ltd., Japan)).

[0276] [Table 3]

[0277]

[0278] Similarly, based on the results of Example 6 and Comparative Examples 11 and 12, it can be seen that, compared with the photocatalytic activity of photocatalytic titanium dioxide with a solution containing iron and silicon (2D) or a solution containing titanium and silicon (2E) added to titanium dioxide particles (1D), the photocatalytic titanium dioxide with a solution containing iron, titanium and silicon (2A) added to titanium dioxide particles (1D) can improve its activity even under conditions of a photocatalyst film containing a binder and under UV irradiation.

[0279] The titanium dioxide particle dispersion of the present invention is useful for preparing photocatalyst films by coating various components made of inorganic materials such as glass and metal and organic materials such as resin, and is particularly useful for preparing transparent photocatalyst films on various components.

Claims

1. A titanium oxide particle, wherein, 1) It contains tin in solid solution and transition metal components to enhance visible light activity. 2) Its surface is coated with iron, titanium, and silicon components. The tin component is derived from at least one of the following: elemental tin, oxides, hydroxides, chlorides, nitrates, sulfates, halides other than chlorides, oxyacid salts, and complex compounds. The transition metal component used to enhance visible light activity is a component derived from at least one of the following: metals, oxides, hydroxides, chlorides, nitrates, sulfates, halides other than chlorides, oxyacid salts, and complexes. Iron is a sulfate. Titanium is composed of chloride. The silicon component is active silicic acid. The molar ratio of iron to titanium dioxide (TiO2 / Fe) is 50–2000, the molar ratio of titanium to titanium dioxide (TiO2 / Ti) is 50–2000, and the molar ratio of silicon to titanium dioxide (TiO2 / Si) is 5–2000. The 50% cumulative distribution diameter of titanium oxide particles, measured using laser dynamic light scattering, is 3–50 nm.

2. The titanium dioxide particles according to claim 1, wherein, The transition metal component dissolved in the titanium dioxide particles to enhance visible light activity is at least one selected from vanadium, chromium, manganese, niobium, molybdenum, rhodium, tungsten, and cerium.

3. The titanium dioxide particles according to claim 2, wherein, The transition metal component dissolved in the titanium dioxide particles to enhance visible light activity is at least one selected from molybdenum, tungsten, and vanadium. The molybdenum component is a derivative of at least one of the following: elemental molybdenum, oxides, hydroxides, chlorides, nitrates, sulfates, halides other than chlorides, molybdic acid and its salts, and complexes. The tungsten component is a component derived from at least one of the following: elemental tungsten, oxides, hydroxides, chlorides, nitrates, sulfates, halides other than chlorides, tungstic acid and oxyacid salts, and complexes. The vanadium component is a component derived from at least one of the following: elemental vanadium, oxides, hydroxides, chlorides, chlorides, nitrates, sulfates, oxysulfates, halides other than chlorides, oxyacid salts, and complexes.

4. The titanium dioxide particles according to claim 3, wherein, The molybdenum component is derived from at least one of oxides, chlorides, and oxyacids and their salts. The tungsten component is derived from at least one of oxides, chlorides, and oxoacids. The vanadium component is a component derived from at least one of oxides, chlorides, chlorides, oxysulfates, and oxyacids.

5. The titanium dioxide particles according to claim 1, wherein, The tin content dissolved in the titanium oxide particles, expressed as a molar ratio of TiO2 / Sn to titanium oxide, ranges from 1 to 1000.

6. The titanium dioxide particles according to claim 3, wherein, The contents of molybdenum, tungsten and vanadium dissolved in titanium oxide particles, respectively, are 1 to 10000 based on their molar ratios to titanium oxide, TiO2 / Mo, TiO2 / W or TiO2 / V.

7. A titanium dioxide particle dispersion, wherein, The titanium oxide particles according to any one of claims 1 to 6 are dispersed in an aqueous dispersion medium.

8. The titanium dioxide particle dispersion according to claim 7, wherein, It further contains adhesives.

9. The titanium dioxide particle dispersion according to claim 8, wherein, The adhesive is a silicone compound adhesive.

10. A photocatalyst thin film, wherein, It comprises titanium oxide particles according to any one of claims 1 to 6.

11. The photocatalyst thin film according to claim 10, wherein, It further contains adhesives.

12. A photocatalytic product, wherein, It has the photocatalyst film of claim 10 on its surface.

13. A method for manufacturing the titanium dioxide particle dispersion of claim 7, comprising the steps (1) to (4) below, wherein, (1) A process for manufacturing a peroxytitanic acid solution containing tin and transition metal components from raw materials titanium compounds, tin compounds, transition metal compounds, alkaline substances, hydrogen peroxide and an aqueous dispersion medium. The raw material titanium compound is at least one selected from inorganic acid salts of titanium, organic acid salts of titanium, and titanium hydroxide precipitated by hydrolysis with the addition of an alkali to an aqueous solution of these. The tin compound is selected from at least one of oxides, chlorides, sulfates, and oxyacid salts. The transition metal compound is at least one selected from molybdenum, tungsten, and vanadium; the molybdenum compound is at least one selected from oxides, chlorides, and oxyacids and their salts; the tungsten compound is at least one selected from oxides, chlorides, and oxyacid salts; and the vanadium compound is at least one selected from oxides, chlorides, chlorides, oxysulfates, and oxyacid salts. The alkaline substance is at least one selected from alkali metal or alkaline earth metal hydroxides and amine compounds. (2) A process of heating the peroxytitanic acid solution containing tin and transition metal components produced in the above (1) process under pressure control and at 80 to 250°C to obtain a titanium oxide particle dispersion containing tin and transition metal components. (3) A process of producing a solution or dispersion of iron, titanium and silicon components from iron compounds, titanium compounds, silicon compounds and an aqueous dispersion medium. Among them, the iron compound is a sulfate, the titanium compound is a chloride, and the silicon compound is an active silicic acid. (4) A process of mixing the titanium oxide particle dispersion produced in step (2) above with a solution or dispersion of iron compound, titanium compound and silicon compound produced in step (3) to obtain a dispersion.

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