Mixture of visible light-responsive photocatalytic titanium oxide fine particles, dispersion liquid thereof, method for producing dispersion liquid, photocatalyst thin film, and member having photocatalyst thin film on surface

Visible light responsive photocatalyst titanium oxide fine particle mixture, dispersion thereof, method for producing dispersion, photocatalyst thin film, and member having photocatalyst thin film on the surface

The present invention relates to a visible light responsive photocatalyst titanium oxide fine particle mixture, a dispersion thereof, a method for preparing the dispersion, a photocatalyst thin film formed using the dispersion, and a member on which the photocatalyst thin film is formed, and more particularly, to visible light (400 to 800 nm) It relates to a visible light responsive photocatalyst titanium oxide fine particle mixture, a dispersion thereof, a method for producing a dispersion, a photocatalyst thin film, and a member having a photocatalyst thin film on the surface, which can easily produce a highly transparent photocatalyst thin film that expresses photocatalytic activity only by itself.

Photocatalytic titanium oxide fine particles are widely used for cleaning, deodorizing, antibacterial, and the like of the surface of a substrate. The photocatalytic reaction refers to a reaction caused by excited electrons and holes generated by the absorption of light by titanium oxide. It is thought that the decomposition of organic matter mainly occurs by the mechanism of the following [1] and [2]. [1] The generated excited electrons and holes undergo a redox reaction with oxygen or water adsorbed on the titanium oxide surface, and the generated active species decomposes organic matter. [2] The organic matter adsorbed on the titanium oxide surface is directly oxidized and decomposed by the generated holes.

Recently, the application of photocatalysis as described above has been applied not only to outdoor use where ultraviolet light can be used, but also to indoor spaces irradiated with light sources such as fluorescent lamps where light in the visible region (wavelength 400 to 800 nm) occupies most. A review is being carried out. For example, a tungsten oxide photocatalyst (Japanese Patent Application Laid-Open No. 2009-148700: Patent Document 1) has been developed as a visible light responsive photocatalyst. Since tungsten is a rare element, it is desired to improve the visible light activity of a photocatalyst using the general-purpose element titanium. is becoming

As a method for improving the visible light activity of a photocatalyst using titanium oxide, a method of supporting iron or copper on the surface of titanium oxide fine particles or metal-doped titanium oxide fine particles (for example, Japanese Patent Application Laid-Open No. 2012-210632: Patent Document 2, JP Japanese Patent Application Laid-Open No. 2010-104913: Patent Document 3, Japanese Patent Application Laid-Open No. 2011-240247: Patent Document 4, Japanese Patent Application Laid-Open No. 7-303835: Patent Document 5) or a transition metal that enhances tin and visible light activity (doped)) of titanium oxide fine particles and titanium oxide fine particles in which copper is dissolved, respectively, and then mixed and used (WO2014/045861: Patent Document 6) and the like are known.

In the latter (Patent Document 6) method of preparing titanium oxide particles in which tin and a transition metal that enhances visible light activity are dissolved and titanium oxide particles in which copper is dissolved, respectively, and mix and use, all metals other than titanium are used in titanium oxide particles. Since it is in solid solution, there is an advantage that a photocatalyst thin film with high durability is obtained which is stable and difficult to modify.

<p><patcit num="0001"><text>Japanese Patent Application Laid-Open No. 2009-148700</text></patcit><patcit num="0002"><text>Japanese Patent Laid-Open No. 2012-210632</text></patcit><patcit num="0003"><text>Japanese Patent Laid-Open No. 2010-104913</text></patcit><patcit num="0004"><text>Japanese Patent Laid-Open No. 2011-240247</text></patcit><patcit num="0005"><text>Japanese Patent Application Laid-Open No. 7-303835</text></patcit><patcit num="0006"><text>WO2014/045861</text></patcit></p>

<p>The present invention relates to a mixture of visible light responsive photocatalyst titanium oxide fine particles capable of obtaining a different type of high visible light activity from the prior art by combining and mixing titanium oxide fine particles containing different transition metals, etc. An object of the present invention is to provide a photocatalyst thin film formed by using the photocatalyst thin film, and a member having a photocatalyst thin film on the surface.</p>

<p>As one method for achieving the above object, the present inventors have prepared second titanium oxide fine particles in which tin, which is the first titanium oxide fine particles used in Patent Document 4, and a transition metal that enhances visible light activity are dissolved in solid solution. By making changes, a search for a new material exhibiting high photocatalytic activity under the condition of only visible light was conducted. Then, the titanium oxide fine particles in which the copper component, which is the second titanium oxide fine particles used in Patent Document 6, is dissolved in a solid solution, shows some photocatalytic activity even under the condition of only visible light (400 to 800 nm), but surprisingly, it is almost unsurprisingly under the condition of only visible light alone. When titanium oxide fine particles containing an iron group element component that does not exhibit photocatalytic activity are blended as the second titanium oxide fine particles, the same high photocatalytic activity is exhibited as when titanium oxide fine particles containing a copper component are combined under conditions of only visible light. could see that</p><p>When the titanium oxide fine particles containing this iron group element component were mixed as the second titanium oxide fine particles were examined in more detail, when the acetaldehyde gas contained in the air was decomposed under visible light, what was obtained from the materials so far The decomposition activity was obtained even in the low concentration region, which was difficult, and it was possible to lower it to 0.03ppm or less, the indoor concentration guideline value (acetaldehyde) of indoor air established by the Ministry of Health, Labor and Welfare in Japan within a significant time under visible light conditions. Further, it was found that the decomposition activity was increased when the chromium group element component was further dissolved in the titanium oxide fine particles in which the iron group element component was dissolved. That is, a film formation using a visible light responsive photocatalytic titanium oxide fine particle dispersion containing first titanium oxide fine particles in which tin and a transition metal that enhances visible light activity are solid-dissolved and second titanium oxide fine particles in which an iron group element component and a chromium group element component are solid-dissolved. It was found that, when one photocatalytic membrane is used, high decomposition activity can be obtained even at a low concentration of a decomposition substrate, which has hitherto been difficult under visible light conditions, leading to the achievement of the present invention.</p><p>Accordingly, the present invention provides a visible light responsive photocatalyst titanium oxide fine particle mixture shown below, a dispersion thereof, a method for producing the dispersion, and a member having a photocatalyst thin film formed using the dispersion on the surface thereof.</p><p>〔1〕 </p><p>Two types of first titanium oxide fine particles in which a tin component and a transition metal component that enhances the visible light responsiveness (however, except for an iron group element component) are solid-dissolved, and a second titanium oxide particle in which an iron group element component and a chromium group element component are solid-dissolved. A visible light responsive photocatalyst titanium oxide fine particle mixture, characterized in that it contains titanium oxide fine particles of</p><p>〔2〕 </p><p>The visible light responsive photocatalytic titanium oxide according to [1], wherein the mixing ratio of the first titanium oxide fine particles and the second titanium oxide fine particles is 99 to 0.01 in each mass ratio [(first titanium oxide fine particles)/(second titanium oxide fine particles)] particulate mixture.</p><p>〔3〕 </p><p>The visible light responsive photocatalytic titanium oxide fine particle mixture according to [1] or [2], wherein the content of the tin component contained in the first titanium oxide fine particles is 1 to 1,000 in a molar ratio (Ti/Sn) to titanium.</p><p>〔4〕 </p><p>Any one of [1] to [3], wherein the transition metal component dissolved in the first titanium oxide fine particles is at least one selected from vanadium, chromium, manganese, niobium, molybdenum, rhodium, antimony, tungsten, and cerium. The visible light responsive photocatalyst titanium oxide fine particle mixture described in.</p><p>〔5〕 </p><p>The visible light responsive photocatalytic titanium oxide fine particle mixture according to [4], wherein the transition metal component dissolved in the first titanium oxide fine particles is at least one selected from molybdenum, tungsten and vanadium.</p><p>〔6〕 </p><p>The visible light responsive photocatalytic titanium oxide fine particle mixture according to [5], wherein the content of the molybdenum or tungsten component contained in the first titanium oxide fine particles is 1 to 1,000 in a molar ratio with titanium (Ti/Mo or W).</p><p>〔7〕 </p><p>The visible light responsive photocatalytic titanium oxide fine particle mixture according to [5], wherein the content of the vanadium component contained in the first titanium oxide fine particles is 10 to 10,000 in a molar ratio (Ti/V) to titanium.</p><p>〔8〕 </p><p>The visible light responsive photocatalytic titanium oxide fine particles according to any one of [1] to [7], wherein the content of the iron group element component contained in the second titanium oxide fine particles is 1 to 1,000 in a molar ratio with titanium (Ti/iron group element). mixture.</p><p>〔9〕 </p><p>The visible light responsive photocatalytic titanium oxide fine particle mixture according to any one of [1] to [8], wherein the iron group element component dissolved in the second titanium oxide fine particles is an iron component.</p><p>〔10〕 </p><p>The visible light responsive photocatalytic oxidation according to any one of [1] to [9], wherein the content of the chromium group element component contained in the second titanium oxide fine particles is 1 to 1,000 in a molar ratio with titanium (Ti/chromium group element). Titanium particulate mixture.</p><p>〔11〕 </p><p>The visible light responsive photocatalytic titanium oxide fine particle mixture according to any one of [1] to [10], wherein the chromium group element component dissolved in the second titanium oxide fine particles is at least one selected from molybdenum and tungsten components.</p><p>〔12〕 </p><p>First titanium oxide fine particles in which a tin component and a transition metal component that enhances the visible light responsiveness (however, except for an iron group element component) are dissolved in an aqueous dispersion medium, and second titanium oxide fine particles in which an iron group element component and a chromium group element component are dissolved in a solid solution A visible light responsive photocatalytic titanium oxide fine particle dispersion liquid, characterized in that two types of titanium oxide fine particles are dispersed.</p><p>〔13〕 </p><p>The visible light responsive photocatalytic titanium oxide dispersion according to [12], further comprising a binder.</p><p>〔14〕 </p><p>The visible light responsive photocatalytic titanium oxide fine particle dispersion liquid according to [13], wherein the binder is a silicon compound binder.</p><p>〔15〕 </p><p>A photocatalyst thin film comprising the mixture of the visible light responsive photocatalyst titanium oxide fine particles according to any one of [1] to [11].</p><p>〔16〕 </p><p>The photocatalyst thin film according to [15], further comprising a binder.</p><p>〔17〕 </p><p>A member in which the photocatalyst thin film of [15] or [16] is formed on the surface of the substrate.</p><p>〔18〕 </p><p>(1) a process for preparing a solution of peroxotitanic acid containing tin and a transition metal component from a raw titanium compound, a tin compound, a transition metal compound (except for an iron group element compound), a basic substance, hydrogen peroxide and an aqueous dispersion medium;</p><p>(2) heating the peroxotitanic acid solution containing tin and transition metal components prepared in the step (1) at 80 to 250° C. under pressure control to obtain a dispersion of titanium oxide particles containing tin and transition metal components;</p><p>(3) a step of preparing a solution of peroxotitanic acid containing an iron group element and a chromium group element component from a raw titanium compound, an iron group element compound, a chromium group element compound, a basic substance, hydrogen peroxide and an aqueous dispersion medium;</p><p>(4) The peroxotitanic acid solution containing iron group elements and chromium group elements prepared in the step (3) is heated at 80 to 250° C. under pressure control, and the titanium oxide fine particle dispersion solution containing iron group elements and chromium group elements is obtained. obtaining process,</p><p>(5) A step of mixing the two types of titanium oxide fine particle dispersions prepared in the steps (2) and (4) above</p><p>A method for producing a visible light responsive photocatalyst titanium oxide fine particle dispersion, characterized in that it has a.</p>

<p>According to the present invention, a mixture of visible light responsive photocatalyst titanium oxide fine particles that can easily produce a photocatalyst thin film with high transparency that expresses photocatalytic activity only with visible light (400 to 800 nm), a dispersion thereof, a method for producing a dispersion, and a dispersion using the It is possible to provide a member having on its surface the photocatalyst thin film to be formed.</p>

Hereinafter, the visible light responsive photocatalyst titanium oxide fine particle mixture of the present invention, a dispersion thereof, a method for producing the dispersion, and a member having a photocatalyst thin film on the surface will be described in detail.

The visible light responsive photocatalytic titanium oxide fine particle mixture of the present invention is a mixture containing first titanium oxide fine particles and second titanium oxide fine particles, which are titanium oxide fine particles having different compositions from each other, and in particular, this mixture is preferably used as a dispersion.

&lt;Visible light responsive photocatalyst titanium oxide particle dispersion solution&gt;

The visible light responsive photocatalytic titanium oxide fine particle dispersion liquid of the present invention is one in which first titanium oxide fine particles and second titanium oxide fine particles, which are titanium oxide fine particles having different compositions, are dispersed in an aqueous dispersion medium, and the first titanium oxide fine particles are transitioned from the tin component Titanium oxide fine particles in which a metal component (however, iron group element components are excluded) are solid-dissolved, and the second titanium oxide fine particles are titanium oxide fine particles in which an iron group element component and a chromium group element component are solid-dissolved.

Here, the solid solution refers to a mixed phase in which atoms at the lattice points of one crystal phase are substituted with other atoms, or other atoms are inserted into the lattice gaps, that is, a mixed phase in which other substances are dissolved in a certain crystal phase, and a homogeneous phase as a crystal phase. Substitution-type solid solutions in which solvent atoms at lattice points are substituted with solute atoms are referred to as substitutional solid solutions, and interstitial solid solutions in which solute atoms enter lattice gaps are referred to herein as both.

In the titanium oxide fine particles of the present invention, the first titanium oxide fine particles form a solid solution with at least a part of tin and transition metal atoms (however, except for the iron group element component), and the second titanium oxide fine particle includes an iron group element component and It is characterized in that it forms a solid solution with at least a part of the chromium group element component. The solid solution may be a substitution type or an interstitial type. The substitutional solid solution is formed by replacing the titanium sites of the titanium oxide crystal with various metal atoms, and the interstitial solid solution is formed by entering various metal atoms into the lattice gaps of the titanium oxide crystal. When various metal atoms are dissolved in titanium oxide, when the crystal phase is measured by X-ray diffraction or the like, only the peak of the crystal phase of titanium oxide is observed, and the peak of the compound derived from the various metal atoms added is not observed.

The method of dissolving the dissimilar metal in the metal oxide crystal is not particularly limited, but a gas phase method (CVD method, PVD method, etc.), a liquid phase method (hydrothermal method, sol-gel method, etc.), a solid phase method (high temperature firing method, etc.), etc. are mentioned. have.

As a crystalline phase of the titanium oxide fine particles, there are usually three known rutile type, anatase type, and brookite type, and it is preferable that the first or second titanium oxide fine particles mainly use a rutile type or an anatase type. In particular, the first titanium oxide fine particles are mainly preferably of the rutile type, and the second titanium oxide fine particles are mainly preferably of the anatase type. In addition, "mainly" as used herein means that it contains usually 50 mass % or more, preferably 70 mass % or more, more preferably 90 mass % or more, in the whole titanium oxide fine particle crystal, and may be 100 mass %.

In addition, as the dispersion medium of the dispersion liquid, an aqueous solvent is usually used, and water is preferably used, but a mixed solvent of water and a hydrophilic organic solvent mixed with water in an arbitrary ratio may be used. As water, deionized water, distilled water, pure water, etc. are preferable, for example. Examples of the hydrophilic organic solvent include alcohols such as methanol, ethanol and isopropanol, glycols such as ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and propylene glycol. Glycol ethers, such as -n-propyl ether, are preferable. When using a mixed solvent, the ratio of the hydrophilic organic solvent in a mixed solvent is more than 0 mass %, It is preferable that it is 50 mass % or less, More preferably, it is 20 mass % or less, More preferably, it is 10 mass % or less.

The first titanium oxide fine particles are titanium oxide fine particles in which a tin component and a transition metal component other than an iron group component that enhances visible light activity are dissolved in a solid solution, and the transition metal is an element selected from Groups 3 to 11 of the periodic table, As the transition metal component, the height can be selected from vanadium, chromium, manganese, niobium, molybdenum, rhodium, antimony, tungsten, cerium, and the like, and among them, molybdenum, tungsten, and vanadium are preferably selected.

The tin component dissolved in the first titanium oxide fine particles is for enhancing the visible light responsiveness of the photocatalyst thin film, and may be derived from a tin compound, for example, tin metal (Sn), oxide (SnO, SnO).₂), hydroxide, chloride (SnCl₂, SnCl₄), nitrate (Sn(NO₃)₂), sulfate (SnSO₄), a halide, a complex compound, and the like, and one or a combination of two or more thereof may be used. Among them, oxides (SnO, SnO₂), chloride (SnCl₂, SnCl₄), sulfate (SnSO₄It is preferable to use).

Content of the tin component in 1st titanium oxide microparticles|fine-particles is 1-1, 000 in molar ratio (Ti/Sn) with titanium, Preferably it is 5-500, More preferably, it is 5-100. This is because, when the molar ratio is less than 1, the content rate of titanium oxide is lowered and the photocatalytic effect is not sufficiently exhibited, and when the molar ratio is more than 1,000, the visible light responsiveness may become insufficient.

The transition metal component dissolved in the first titanium oxide fine particles may be derived from the transition metal compound, and may include metals, oxides, hydroxides, chlorides, nitrates, sulfates, halides, and various complex compounds. Two or more types are used.

The content of the transition metal component in the first titanium oxide fine particles can be appropriately selected depending on the type of the transition metal component, and the molar ratio with titanium (Ti/transition metal) is in the range of 1 to 10,000, particularly 5 to 1,000. It is preferable that the range of

In this case, when molybdenum is selected as the transition metal component dissolved in the first titanium oxide fine particles, the molybdenum component may be derived from a molybdenum compound, for example, molybdenum metal (Mo), oxide (MoO₂, MoO₃), molybdenic acid and its salts (H₂MoO₄, Na₂MoO₄), hydroxide, chloride (MoCl₃, MoCl₅), nitrates, sulfates, halides, complex compounds, and the like, and one or a combination of two or more thereof may be used. Among them, oxides (MoO₂, MoO₃), chloride (MoCl₃, MoCl₅It is preferable to use).

The content of the molybdenum component in the first titanium oxide fine particles is 1 to 1,000, preferably 2 to 100, more preferably 2 to 50 in a molar ratio (Ti/Mo) to titanium. When the molar ratio is less than 1, the content of titanium oxide is lowered and the photocatalytic effect may not be sufficiently exhibited. Because there are things that cannot be obtained.

When tungsten is selected as the transition metal component dissolved in the first titanium oxide fine particles, the tungsten component may be derived from a tungsten compound, for example, tungsten metal (W) or oxide (WO).₃), tungstic acid and its salts (H₂WO₄, Na₂WO₄, K₂WO₄), hydroxide, chloride (WCl₄, WCl₆), nitrates, sulfates, halides, complex compounds, and the like, and one or a combination of two or more thereof may be used. Among them, oxides (WO₃), tungstic acid and its salts (H₂WO₄, Na₂WO₄, K₂WO₄), chloride (WCl₄, WCl₆It is preferable to use).

Content of the tungsten component in 1st titanium oxide microparticles|fine-particles is 1-1, 000 in molar ratio (Ti/W) with titanium, Preferably it is 2-100, More preferably, it is 2-50. When the molar ratio is less than 1, the content of titanium oxide is lowered and the photocatalytic effect may not be sufficiently exhibited. Because there are things that cannot be obtained.

When vanadium is selected as the transition metal component dissolved in the first titanium oxide fine particles, the vanadium component may be derived from a vanadium compound, for example, a metal (V) of vanadium, an oxide (VO, V₂O₃, VO₂, V₂O₅), hydroxide, chloride (VCl₅), oxychloride (VOCl)₃), nitrate, sulfate, oxysulfate (VOSO₄), a halide, a complex compound, and the like, and one or a combination of two or more thereof may be used. Among them, oxides (V₂O₃, V₂O₅), chloride (VCl₅), oxychloride (VOCl)₃), oxysulfate (VOSO₄It is preferable to use).

Content of the vanadium component in 1st titanium oxide microparticles|fine-particles is 10-10, 000 in molar ratio (Ti/V) with titanium, Preferably it is 100-10, 000, More preferably, it is 100-5,000. When the molar ratio is less than 10, the content rate of titanium oxide crystals decreases and the photocatalytic effect may not be sufficiently exhibited. This is because activity may not be obtained.

As the transition metal component dissolved in the first titanium oxide fine particles, a plurality of molybdenum, tungsten and vanadium may be selected. In that case, each component amount can be selected from the said range, However, the molar ratio [Ti/(Mo+W+V)] of the sum total of each component amount and titanium is 1 or more and less than 10,000.

The 1st titanium oxide microparticles|fine-particles may be used individually by 1 type, and may be used in combination of 2 or more type. When two or more types which have different visible light responsiveness are combined, the effect that visible light activity becomes high may be acquired.

The second titanium oxide fine particles have a composition different from that of the first titanium oxide fine particles, and characteristically, an iron group element component and a chromium group element component are solid-dissolved. It does not contain any transition metal or tin other than that.

Examples of the iron group metal dissolved in the second titanium oxide fine particles include iron, cobalt, and nickel, and among them, iron element is preferable.

The chromium group metal dissolved in the second titanium oxide fine particles includes chromium, molybdenum and tungsten, and among them, molybdenum and tungsten elements are preferable.

The iron group element component dissolved in the second titanium oxide fine particles may be derived from an iron group element compound, for example, iron metal (Fe), oxide (Fe)₂O₃, Fe₃O₄), hydroxide (FeO(OH)), chloride (FeCl)₂, FeCl₃), nitrate (Fe(NO₃)₃), sulfate (FeSO₄, Fe₂(SO₄)₃), a halide, a complex compound, etc., and may be used alone or in combination of two or more thereof. Among them, oxides (Fe₂O₃, Fe₃O₄), hydroxide (FeO(OH)), chloride (FeCl)₂, FeCl₃), nitrate (Fe(NO₃)₃), sulfate (FeSO₄, Fe₂(SO₄)₃It is preferable to use).

The content of the iron group element component in the second titanium oxide fine particles is in a molar ratio with titanium (Ti/iron group element) from 1 to 1,000, preferably from 2 to 200, more preferably from 5 to 100. This is because, when the molar ratio is less than 1, the content rate of titanium oxide is lowered and the photocatalytic effect is not sufficiently exhibited, and when the molar ratio is more than 1,000, the visible light responsiveness may become insufficient.

When molybdenum is selected as the chromium group element component dissolved in the second titanium oxide fine particles, the molybdenum component may be derived from a molybdenum compound, for example, metal (Mo), oxide of molybdenum. (MoO₂, MoO₃), molybdenic acid and its salts (H₂MoO₄, Na₂MoO₄), hydroxide, chloride (MoCl₃, MoCl₅), nitrates, sulfates, halides, complex compounds, and the like, and one or a combination of two or more thereof may be used. Among them, oxides (MoO₂, MoO₃), chloride (MoCl₃, MoCl₅It is preferable to use).

The content of the molybdenum component in the second titanium oxide fine particles is 1 to 1,000, preferably 2 to 100, more preferably 2 to 50 in molar ratio (Ti/Mo) to titanium. When the molar ratio is less than 1, the content of titanium oxide is lowered and the photocatalytic effect may not be sufficiently exhibited. Because there are things that cannot be obtained.

When tungsten is selected as the chromium group element component dissolved in the second titanium oxide fine particles, the tungsten component may be derived from a tungsten compound, for example, a metal (W) of tungsten, an oxide (WO)₃), tungstic acid and its salts (H₂WO₄, Na₂WO₄, K₂WO₄), hydroxide, chloride (WCl₄, WCl₆), nitrates, sulfates, halides, complex compounds, and the like, and one or a combination of two or more thereof may be used. Among them, oxides (WO₃), tungstic acid and its salts (H₂WO₄, Na₂WO₄, K₂WO₄), chloride (WCl₄, WCl₆) is preferably used. Further, when molybdenum or tungsten is used as the transition metal for the first titanium oxide fine particles, it is more preferable to use molybdenum or tungsten as the chromium group element also for the second titanium oxide fine particles.

Content of the tungsten component in 2nd titanium dioxide microparticles|fine-particles is 1-1, 000 in molar ratio with titanium (Ti/W), Preferably it is 2-100, More preferably, it is 2-50. When the molar ratio is less than 1, the content of titanium oxide is lowered and the photocatalytic effect may not be sufficiently exhibited. Because there are things that cannot be obtained.

It is preferable to select molybdenum and/or tungsten as the chromium group element component dissolved in the second titanium oxide fine particles, and the molar ratio of the total amount of each component of chromium, molybdenum and tungsten to titanium [Ti/(chromium group) total amount of elements)] is 1 or more and 1,000 or less. Moreover, 2nd titanium oxide microparticles|fine-particles may be used individually by 1 type, and may be used in combination of 2 or more type. When two or more types which have different visible light responsiveness are combined, the effect that visible light activity becomes high may be acquired.

The first titanium oxide fine particles and the second titanium oxide fine particles in the visible light responsive photocatalytic titanium oxide fine particle mixture have a 50% cumulative distribution diameter (D on a volume basis) measured by a dynamic light scattering method using laser light.₅₀) (hereinafter, sometimes referred to as "average particle diameter") is preferably 5 to 30 nm, more preferably 5 to 20 nm. This is because the photocatalytic activity may become insufficient when the average particle diameter is less than 5 nm, and the dispersion may become opaque when it exceeds 30 nm. Moreover, as an apparatus for measuring an average particle diameter, Nanotrac UPA-EX150 (made by Nikkiso Co., Ltd.), LA-910 (made by Horiba Corporation) etc. can be used, for example.

The mixing ratio of the first titanium oxide fine particles and the second titanium oxide fine particles contained in the visible light responsive photocatalytic titanium oxide fine particles mixture is 99 to 0.01 in each mass ratio [(first titanium oxide fine particles)/(second titanium oxide fine particles)] It is preferable, More preferably, it is 19-0.05, More preferably, it is 10-0.5. This is because visible light activity may become insufficient when the said mass ratio is more than 99 or less than 0.01.

The concentration of the total of the first titanium oxide fine particles and the second titanium oxide fine particles in the visible light responsive photocatalyst titanium oxide fine particle dispersion is preferably 0.01 to 20 mass % from the point of view of ease of production of a photocatalyst thin film having a required thickness, particularly 0.5 to 10 mass % is preferable.

In addition, a binder may be added to the visible light responsive photocatalytic titanium oxide fine particle dispersion for the purpose of making it easy to apply the dispersion to the surfaces of various members described later and to make the fine particles easy to adhere. Examples of the binder include metal compound-based binders containing silicon, aluminum, titanium, zirconium, and the like, organic resin-based binders containing fluorine-based resins, acrylic resins, urethane-based resins, and the like.

The mass ratio of the binder and titanium oxide [binder/titanium oxide] is 0.01 to 99, more preferably 0.1 to 9, still more preferably 0.4 to 2.5, and it is preferably added and used. This is because when the said mass ratio is less than 0.01, the adhesion of the titanium oxide fine particles to the surface of various members becomes inadequate, and when it exceeds 99, visible light activity may become inadequate.

Among them, in order to obtain an excellent photocatalytic thin film with high photocatalytic action and transparency, a silicon compound-based binder is particularly used in a compounding ratio (mass ratio of silicon compound and titanium oxide) 1:99 to 99:1, more preferably 10:90 to 90:10, More preferably, it is preferable to use it by adding it in the range of 30:70 to 70:30. Here, the silicon compound binder is a colloidal dispersion, solution, or emulsion of a silicon compound comprising a solid or liquid silicon compound in an aqueous dispersion medium, and specifically, colloidal silica (preferred particle size of 1 to 150 nm); silicate solutions such as silicates; silane, siloxane hydrolyzate emulsions; silicone resin emulsions; An emulsion of a copolymer of a silicone resin, such as a silicone-acrylic resin copolymer and a silicone-urethane resin copolymer, and another resin, etc. are mentioned.

&lt;Method for producing visible light responsive photocatalyst titanium oxide fine particle dispersion&gt;

The manufacturing method of the visible light responsive photocatalytic titanium oxide fine particle dispersion of the present invention is prepared by preparing a first titanium oxide fine particle dispersion and a second titanium oxide fine particle dispersion, respectively, and mixing the first titanium oxide fine particle dispersion and the second titanium oxide fine particle dispersion. do.

Specifically, the manufacturing method which has the process of following (1)-(5) is mentioned.

(1) a process for preparing a solution of peroxotitanic acid containing tin and a transition metal component from a raw titanium compound, a tin compound, a transition metal compound (except for an iron group element compound), a basic substance, hydrogen peroxide and an aqueous dispersion medium;

(2) heating the peroxotitanic acid solution containing tin and transition metal components prepared in the step (1) at 80 to 250° C. under pressure control to obtain a dispersion of titanium oxide particles containing tin and transition metal components;

(3) a step of preparing a solution of peroxotitanic acid containing an iron group element and a chromium group element component from a raw titanium compound, an iron group element compound, a chromium group element compound, a basic substance, hydrogen peroxide and an aqueous dispersion medium;

(4) The peroxotitanic acid solution containing iron group elements and chromium group elements prepared in the step (3) is heated at 80 to 250° C. under pressure control, and the titanium oxide fine particle dispersion solution containing iron group elements and chromium group elements is obtained. obtaining process,

(5) A step of mixing the two types of titanium oxide fine particle dispersions prepared in the steps (2) and (4) above.

Steps (1) to (2) are steps for obtaining a first dispersion of titanium oxide fine particles, steps (3) to (4) are steps for obtaining a second dispersion of titanium oxide particles, and step (5) is finally a first step It is a process of obtaining the dispersion liquid containing titanium oxide microparticles|fine-particles and the 2nd titanium oxide microparticles|fine-particles.

As described above, it is preferable to use at least one of a molybdenum compound, a tungsten compound, and a vanadium compound as the transition metal compound used in the step (1)..

・Process (1):

In step (1), peroxo containing a transition metal and a tin component is made by reacting a raw material titanium compound, a transition metal compound (except for an iron group element compound, the same applies hereinafter), a tin compound, a basic substance, and hydrogen peroxide in an aqueous dispersion medium. Prepare a titanic acid solution.

As a reaction method, a basic substance is added to a raw titanium compound in an aqueous dispersion medium to obtain titanium hydroxide, impurity ions other than metal ions contained therein are removed, hydrogen peroxide is added to obtain peroxotitanic acid, and then a transition metal compound and a tin compound are prepared. It may be a method of preparing peroxotitanic acid containing a transition metal and a tin component by adding a transition metal compound and a tin compound to the raw titanium compound and a basic substance in an aqueous dispersion medium, adding and dissolving the transition metal compound and a tin component, followed by hydroxylation containing the transition metal and tin component The method may be used as titanium, in which impurity ions other than the contained metal ions are removed, and hydrogen peroxide is added to obtain peroxotitanic acid containing a transition metal and a tin component.

Further, in the previous stage of the latter, the raw titanium compound and the basic substance in the aqueous dispersion medium are divided into two aqueous dispersion media such as an aqueous dispersion medium in which the raw titanium compound is dispersed and an aqueous dispersion medium in which the basic substance is dispersed, the transition metal compound and the tin compound Depending on the solubility of each compound in the two liquids, each compound may be dissolved in either or both of the two liquids, and then both may be mixed.

Thus, after obtaining the peroxotitanic acid containing a transition metal and a tin component, by subjecting it to the hydrothermal reaction of the process (2) mentioned later, titanium oxide fine particles in which the said various metals were dissolved in titanium oxide can be obtained.

Here, as the raw material titanium compound, for example, inorganic acid salts such as titanium chloride, nitrate and sulfate, organic acid salts such as formic acid, citric acid, oxalic acid, lactic acid, glycolic acid, etc. Titanium hydroxide etc. are mentioned, You may use these 1 type or in combination of 2 or more types. Among them, the chloride of titanium (TiCl₃, TiCl₄It is preferable to use).

As a transition metal compound, a tin compound, and an aqueous dispersion medium, the thing mentioned above is used so that it may become the compounding mentioned above, respectively. In addition, the concentration of the raw titanium compound aqueous solution formed from the raw titanium compound and the aqueous dispersion medium is preferably 60 mass % or less, particularly 30 mass % or less. Although the lower limit of a density|concentration is selected suitably, it is preferable that it is normally 1 mass % or more.

The basic substance is for smoothly turning the raw titanium compound into titanium hydroxide, for example, hydroxides of alkali metals or alkaline earth metals such as sodium hydroxide and potassium hydroxide, and amine compounds such as ammonia, alkanolamines, and alkylamines. And it is used by adding the pH of the raw material titanium compound aqueous solution to 7 or more, particularly pH 7 to 10. Further, the basic substance may be used together with the aqueous dispersion medium as an aqueous solution having an appropriate concentration.

Hydrogen peroxide is for converting the raw titanium compound or titanium hydroxide into peroxotitanium, that is, a titanium oxide compound including a Ti-O-O-Ti bond, and is usually used in the form of hydrogen peroxide solution. It is preferable that the addition amount of hydrogen peroxide sets it as 1.5-20 times mole of the total moles of a transition metal, V, and Sn. Further, in the reaction of adding hydrogen peroxide to use a raw titanium compound or titanium hydroxide as peroxotitanic acid, the reaction temperature is preferably 5 to 80° C., and the reaction time is preferably 30 minutes to 24 hours.

The peroxotitanic acid solution containing the transition metal and tin component obtained in this way may contain an alkaline substance or an acidic substance for pH adjustment etc. Examples of the alkaline substance referred to herein include ammonia, sodium hydroxide, calcium hydroxide, and alkylamine. Examples of the acidic substance include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, carbonic acid, phosphoric acid, hydrogen peroxide, and formic acid, citric acid, oxalic acid, Organic acids, such as lactic acid and glycolic acid, are mentioned. In this case, the pH of the peroxotitanic acid solution containing the obtained transition metal and tin is preferably 1 to 9, particularly 4 to 7, from the viewpoint of safety of handling.

・Process (2):

In the step (2), the peroxotitanic acid solution containing the transition metal and the tin component obtained in the step (1) is subjected to a hydrothermal reaction for 0.01 to 24 hours at a temperature of 80 to 250° C., preferably 100 to 250° C. under pressure control. to provide. The reaction temperature is preferably 80 to 250° C. from the viewpoint of reaction efficiency and controllability of the reaction. As a result, peroxotitanic acid containing a transition metal and a tin component is converted into fine particles of titanium oxide containing a transition metal and a tin component. In addition, when the reaction temperature to be pressure-controlled exceeds the boiling point of the dispersion medium, it means that the reaction temperature is maintained by appropriately pressurizing so as to maintain the reaction temperature. do. The pressure used here is usually about 0.12 to 4.5 MPa, preferably about 0.15 to 4.5 MPa, and more preferably about 0.20 to 4.5 MPa. It is preferable that reaction time is 1 minute - 24 hours. By this process (2), the titanium oxide fine particle dispersion liquid containing the transition metal and tin component which are 1st titanium oxide fine particles is obtained.

The particle diameter of the titanium oxide fine particles obtained here is preferably in the range as described above, but it is possible to control the particle diameter by adjusting the reaction conditions. For example, by shortening the reaction time or temperature increase time, the particle diameter is reduced can do.

·Process (3):

In step (3), separately from the steps (1) to (2), the raw material titanium compound, iron group element compound, chromium group element compound, basic substance and hydrogen peroxide are reacted in an aqueous dispersion medium to contain iron group element and chromium group element component A solution of peroxotitanic acid is prepared. As a reaction method, it can carry out by the completely similar method except using an iron group element compound and a chromium group element compound instead of the transition metal compound and a tin compound in the said process (1).

That is, the starting material titanium compound (the same as the raw material titanium compound of the first titanium oxide), iron group compound, chromium group compound, aqueous dispersion medium, basic substance, and hydrogen peroxide are each used so that the above-mentioned ones are in the above-mentioned formulation, provided to the reaction under the temperature and time described above.

The peroxotitanic acid solution containing the iron group element and the chromium group element component obtained in this way may also contain an alkaline substance or an acidic substance for pH adjustment etc. can be treated similarly.

·Process (4):

In the step (4), the peroxotitanic acid solution containing the iron group element and the chromium group element component obtained in the step (3) is heated under pressure control at a temperature of 80 to 250° C., preferably 100 to 250° C. for 0.01 to 24 hours. provide for the reaction. From the viewpoint of reaction efficiency and controllability of the reaction, 80 to 250° C. is appropriate for the reaction temperature, and as a result, peroxotitanic acid containing iron group elements and chromium group elements is converted into titanium oxide particles containing iron group elements and chromium group elements.. In addition, when the reaction temperature to be pressure-controlled exceeds the boiling point of the dispersion medium, it means that the reaction temperature is maintained by appropriately pressurizing so as to maintain the reaction temperature. do. The pressure used here is usually about 0.12 to 4.5 MPa, preferably about 0.15 to 4.5 MPa, and more preferably about 0.20 to 4.5 MPa. It is preferable that reaction time is 1 minute - 24 hours. By this step (4), a dispersion liquid of titanium oxide fine particles containing an iron group element and a chromium group element component as second titanium oxide fine particles is obtained.

The particle diameter of the titanium oxide fine particles obtained here is also preferably in the range as described above, but it is possible to control the particle diameter by adjusting the reaction conditions. For example, by shortening the reaction time or temperature increase time, the particle diameter is reduced can do.

・Process (5):

In the step (5), the first dispersion of titanium oxide particles obtained in the steps (1) to (2) and the second dispersion of titanium oxide particles obtained in the steps (3) to (4) are mixed. The mixing method is not specifically limited, The method of stirring with a stirrer may be sufficient, and the method of disperse|distributing with an ultrasonic disperser may be sufficient. It is preferable that the temperature at the time of mixing is 20-100 degreeC, and time is 1 minute - 3 hours. Regarding the mixing ratio, the mixture may be mixed so that the mass ratio of the titanium oxide fine particles in each titanium oxide fine particle dispersion may be as described above.

The mass of titanium oxide fine particles contained in each titanium oxide fine particle dispersion can be calculated from the mass and concentration of each titanium oxide fine particle dispersion. In addition, in the method of measuring the concentration of the titanium oxide fine particle dispersion, a part of the titanium oxide fine particle dispersion is sampled, and the mass of the non-volatile matter (titanium oxide fine particles) after heating at 105° C. for 3 hours to volatilize the solvent and the sampled titanium oxide fine particle dispersion It can be calculated according to the following formula from the mass of

Concentration (%) of titanium oxide fine particle dispersion = [mass of non-volatile matter (g)/mass of titanium oxide fine particle dispersion (g)] x 100

The concentration of the total of the first titanium oxide fine particles and the second titanium oxide fine particles in the thus prepared dispersion of visible light responsive photocatalyst titanium oxide fine particles is 0.01 ~ 20 mass % is preferable, and 0.5-10 mass % is especially preferable. Regarding the concentration adjustment, when the concentration is higher than the desired concentration, the concentration can be decreased by diluting by adding an aqueous solvent, and when the concentration is lower than the desired concentration, the concentration can be increased by volatilizing or filtering the aqueous solvent. In addition, the concentration can be calculated as described above.

In addition, when adding the above-mentioned binder enhancing the film-forming property, it is preferable to add it to the visible light responsive photocatalyst titanium oxide fine particle dispersion that has been adjusted as described above so as to have a desired concentration after mixing the aqueous binder solution to be added. do.

&lt;Member having a photocatalyst thin film on its surface&gt;

The visible light responsive photocatalyst titanium oxide fine particle dispersion of the present invention can be used to form a photocatalytic film on the surface of various members. Here, the various members are not particularly limited, and examples of the material of the member include an organic material and an inorganic material. They may have various shapes according to each purpose and use.

Examples of the organic material include vinyl chloride resin (PVC), polyethylene (PE), polypropylene (PP), polycarbonate (PC), acrylic resin, polyacetal, fluororesin, silicone resin, ethylene-vinyl acetate copolymer (EVA).), acrylonitrile-butadiene rubber (NBR), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyvinyl butyral (PVB), ethylene-vinyl alcohol copolymer (EVOH), polyimide resin, polyphenylene sulfide (PPS), polyetherimide (PEI), polyetheretherimide (PEEI), polyetheretherketone (PEEK), melamine resin, phenolic resin, acrylonitrile-butada Synthetic resin materials, such as en-styrene (ABS) resin, natural materials, such as natural rubber, or a semi-synthetic material of the said synthetic resin material and a natural material is mentioned. These may be commercialized in the required shape and structure, such as a film, a sheet|seat, a fiber material, a fiber product, other molded articles, and a laminated body.

Examples of the inorganic material include non-metallic inorganic materials and metallic inorganic materials. Examples of the non-metallic inorganic material include glass, ceramic, and stone. These may be commercialized in various forms, such as a tile, glass, a mirror, a wall, and a decoration material. Examples of the metal inorganic material include cast iron, steel materials, iron, iron alloy, aluminum, aluminum alloy, nickel, nickel alloy, zinc die casting, and the like. Plating of the said metallic inorganic material may be performed, the said organic material may be apply|coated, and plating applied to the surface of the said organic material or nonmetallic inorganic material may be sufficient as these.

The visible light responsive photocatalyst titanium oxide fine particle dispersion of the present invention is particularly useful for producing a transparent photocatalyst thin film on a polymer film such as PET among the various members described above.

As a method for forming a photocatalyst thin film on various member surfaces, a visible light responsive photocatalyst titanium oxide fine particle dispersion is applied to the member surface by a known coating method such as spray coating or dip coating, followed by far-infrared drying, IH drying, It may be dried by a known drying method such as hot air drying, and the thickness of the photocatalyst thin film may be selected in various ways, but in general, the range of 10 nm to 10 μm is preferable.

Thereby, the film of the above-mentioned visible light responsive photocatalyst titanium oxide fine particle mixture is formed. In this case, when the binder is contained in the above-mentioned amount in the dispersion, a film containing the titanium oxide fine particle mixture and the binder is formed.

The photocatalytic thin film formed in this way is transparent and not only gives a good photocatalytic action in ultraviolet light (10 to 400 nm) as in the prior art, but also provides a sufficient photocatalytic action with conventional photocatalysts in the visible range. Excellent photocatalytic action is obtained only by (400 to 800 nm), and various members on which this photocatalytic thin film is formed decompose organic matter adsorbed on the surface by the photocatalytic action of titanium oxide, so that the surface of this member is cleaned, deodorized, antibacterial, etc. that can be effective.

(Example)

The present invention will be specifically described below by showing examples and comparative examples, but the present invention is not limited to the following examples. Various measurements in the present invention were performed as follows.

(1) Average particle diameter of titanium oxide fine particles in dispersion (D₅₀)

The average particle diameter of titanium oxide fine particles in the dispersion (D₅₀) was measured using a particle size distribution measuring apparatus (trade name "Nanotrac particle size analyzer UPA-EX150", Nikkiso Co., Ltd.).

(2) Test of acetaldehyde gas decomposition performance of photocatalyst thin film (under LED irradiation)

The activity of the photocatalyst thin film prepared by coating and drying the dispersion was evaluated by decomposition reaction of acetaldehyde gas. Evaluation was performed by the batch-type gas cracking performance evaluation method.

Specifically, a sample for evaluation in which a photocatalyst thin film containing about 20 mg of photocatalyst microparticles as a dry mass was formed on the entire surface of an A4 size (210 mm × 297 mm) PET film in a stainless steel cell with a quartz glass window of a volume of 5 L. A sample was installed. Then, the cell was filled with acetaldehyde gas with a concentration of 5 ppm controlled at 50% humidity, and an LED installed on the upper part of the cell (product model number "TH-211×200SW", CS Co., Ltd., spectral distribution: 400-800 nm) It irradiated with light so that it might become an illumination intensity of 30,000 Lx. When the acetaldehyde gas is decomposed by the photocatalyst on the thin film, the concentration of the acetaldehyde gas in the cell decreases. Therefore, by measuring the concentration, the amount of decomposition of acetaldehyde gas can be obtained. The acetaldehyde gas concentration was measured using a photoacoustic multi-gas monitor (trade name "INNOVA1412", manufactured by LumaSense), and the time required to reduce the acetaldehyde gas concentration from the initial 5 ppm to [1] 1 ppm, and [2] 0.03 ppm The time required to reduce to The test was conducted for up to 50 hours.

[1] Time required to reduce to 1ppm

· Good (marked with ○) … Reduced within 10 hours

・Somewhat bad (marked by △) … Reduced within 25 hours

・Defective (indicated by ×) … No reduction over 25 hours or down to 1 ppm

[2] Time required to reduce to 0.03 ppm

· Good (marked with ○) … Reduced within 20 hours

・Somewhat bad (marked by △) … Reduced within 50 hours

・Defective (indicated by ×) … No reduction at 50 hours or no reduction at all

(3) Identification of the crystalline phase of titanium oxide fine particles

The crystal phase of the titanium oxide fine particles is determined by powder X-ray diffraction of the titanium oxide fine particle powder recovered by drying the obtained dispersion of the titanium oxide fine particles at 105° C. (Note) was identified by measuring.

[Example 1]

&lt;Preparation of titanium oxide fine particle dispersion in which tin and molybdenum are dissolved&gt;

Tin (IV) chloride is added and dissolved in a 36 mass % titanium (IV) chloride aqueous solution so that Ti/Sn (molar ratio) is 20, and this is diluted 10-fold with pure water, and then molybdenum oxide (VI)) to the Ti component in the above-mentioned titanium (IV) chloride aqueous solution so that Ti/Mo (molar ratio) is 20, 10% by mass of ammonia water added and dissolved is gradually added, neutralized and hydrolyzed to obtain tin and molybdenum A precipitate of titanium hydroxide contained was obtained. The pH at this time was 8. The obtained precipitate was deionized by repeating addition of pure water and decantation. H in the titanium hydroxide precipitate containing tin and molybdenum after this deionization treatment₂O₂35% by mass of hydrogen peroxide is added so that /(Ti+Sn+Mo) (molar ratio) becomes 10, and then stirred at 50° C. for 3 hours to fully react, orange-transparent tin and molybdenum-containing peroxotitanic acid A solution (a) was obtained.

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

&lt;Preparation of titanium oxide fine particle dispersion in which iron and tungsten are dissolved&gt;

Iron (III) chloride is added to a 36% by mass aqueous solution of titanium (IV) chloride so that the Ti/Fe (molar ratio) becomes 10, and this is diluted 10-fold with pure water, and then sodium tungsten (VI) oxide is added to the aqueous solution A precipitate of titanium hydroxide containing iron and tungsten was obtained by gradually adding 10 mass % of ammonia water added and dissolved so that the Ti/W (molar ratio) was 33 with respect to the Ti component in the aqueous titanium (IV) chloride solution, neutralized and hydrolyzed. got it The pH at this time was 8. The obtained precipitate was deionized by repeating addition of pure water and decantation. H in the titanium hydroxide precipitate containing iron and tungsten after this deionization treatment₂O₂35 mass % aqueous hydrogen peroxide is added so that /(Ti+Fe+W) (molar ratio) becomes 8, and then stirred for 2 hours at 40° C. to sufficiently react, an orange-transparent iron and tungsten-containing peroxotitanic acid solution (b) was obtained.

Into an autoclave having a volume of 500 mL, 400 mL of a peroxotitanic acid solution (b) containing iron and tungsten is introduced, and this is hydrothermalized for 90 minutes under the conditions of 130 ° C. After that, by adding pure water to adjust the concentration, iron and A dispersion (solid content concentration of 1% by mass) of titanium oxide fine particles (B) in which tungsten was dissolved was obtained. When powder X-ray diffraction measurement of the titanium oxide fine particles (B) was performed, it was found that the observed peak was only that of anatase-type titanium oxide, and that iron and tungsten were dissolved in the titanium oxide.

By mixing the respective dispersions so that the titanium oxide fine particles (A) and the titanium oxide fine particles (B) are (A): (B) = 50:50 in mass ratio, the visible light responsive photocatalytic titanium oxide fine particle dispersion of the present invention (E- 1) was obtained.

Silica binder (colloidal silica, trade name: Snowtex 20, manufactured by Nissan Chemical Industry Co., Ltd., average particle diameter of 10 to 20 nm, SiO₂concentration of 20% by mass aqueous solution) of TiO₂/SiO₂(mass ratio) was added so that it might be set to 1.5, and the coating liquid for evaluation was produced.

The coating solution for evaluation was coated with a #7 wire bar coater to form a photocatalyst thin film (thickness about 80 nm) containing 20 mg of photocatalyst titanium oxide particles on an A4 size PET film, and dried in an oven set at 80 ° C for 1 hour. Thus, a sample member for evaluation of acetaldehyde gas decomposition performance was obtained. The acetaldehyde gas decomposition performance of this photocatalyst thin film was measured by the batch-type gas decomposition performance evaluation method. After irradiation with LED (wavelength 400-800 nm), 1 ppm (good: ○) at 5.1 hours and 0.03 ppm (good: ○) at 10.8 hours acetaldehyde gas concentration was decreased.

[Example 2]

&lt;Preparation of titanium oxide fine particle dispersion in which tin and molybdenum are dissolved&gt;

Tin (IV) chloride was added so that the Ti/Sn (molar ratio) became 33, molybdenum (VI) oxide was added so that the Ti/Mo (molar ratio) was 3.3, and the hydrothermal treatment time was 120 minutes. It carried out similarly to Example 1, and obtained the dispersion liquid (solid content concentration of 1 mass %) of the titanium oxide microparticles|fine-particles (C) in which tin and molybdenum were dissolved. When powder X-ray diffraction measurement of the titanium oxide fine particles (C) was performed, it was found that the observed peaks were only those of rutile-type titanium oxide and anatase-type titanium oxide, and that tin and molybdenum were dissolved in titanium oxide.

By mixing the respective dispersions so that the titanium oxide fine particles (C) and the titanium oxide fine particles (B) are (C):(B)=50:50 in mass ratio, the visible light responsive photocatalytic titanium oxide fine particle dispersion of the present invention (E- 2) was obtained.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the photocatalyst titanium oxide fine particle dispersion (E-2), and acetaldehyde gas decomposition performance was measured. At 7.3 hours after LED irradiation, 1 ppm (good: ○), The acetaldehyde gas concentration decreased from 15.4 hours to 0.03 ppm (good: ○).

[Example 3]

&lt;Preparation of titanium oxide fine particle dispersion in which tin and tungsten are dissolved&gt;

Tin (IV) chloride is added and dissolved in a 36 mass % titanium (IV) chloride aqueous solution so that Ti/Sn (molar ratio) becomes 5, and this is diluted 10-fold with pure water, and then sodium tungsten (VI) oxide is added to the aqueous solution Hydroxide containing tin and tungsten by gradually adding 10 mass % ammonia water added and dissolved so that Ti/W (molar ratio) becomes 10 with respect to the Ti component in the above-mentioned titanium (IV) chloride aqueous solution, neutralizing and hydrolyzing it. A precipitate of titanium was obtained. The pH at this time was 8. The obtained precipitate was deionized by repeating addition of pure water and decantation. H in the titanium hydroxide precipitate containing tin and tungsten after this deionization treatment₂O₂35 mass % hydrogen peroxide solution is added so that /(Ti+Sn+W) (molar ratio) becomes 10, and then stirred at 50° C. for 3 hours to fully react, orange-transparent tin and tungsten-containing peroxotitanic acid solution (d) was obtained.

Into an autoclave with a volume of 500 mL, 400 mL of a tin and tungsten-containing peroxotitanic acid solution (d) is introduced, and this is hydrothermally treated under the conditions of 180° C. for 90 minutes, and then, pure water is added to adjust the concentration by adding tin and A dispersion (solid content concentration of 1% by mass) of titanium oxide fine particles (D) in which tungsten was dissolved was obtained. When powder X-ray diffraction measurement of the titanium oxide fine particles (D) was carried out, it was found that the observed peak was only that of rutile-type titanium oxide, and that tin and tungsten were dissolved in the titanium oxide.

By mixing the respective dispersions so that the titanium oxide fine particles (D) and the titanium oxide fine particles (B) are (D): (B) = 50:50 in mass ratio, the visible light responsive photocatalytic titanium oxide fine particle dispersion of the present invention (E- 3) was obtained.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the photocatalyst titanium oxide fine particle dispersion (E-3), and the acetaldehyde gas decomposition performance was measured. At 6.2 hours after LED irradiation, 1 ppm (good: ○), the acetaldehyde gas concentration decreased from 13.1 hours to 0.03 ppm (good: ○).

[Example 4]

&lt;Preparation of titanium oxide fine particle dispersion in which tin, molybdenum and tungsten are dissolved&gt;

Tin (IV) chloride is added and dissolved in a 36 mass % titanium (IV) chloride aqueous solution so that Ti/Sn (molar ratio) is 20, and this is diluted 10-fold with pure water, and then molybdenum oxide (VI)) with respect to the Ti component in the above-mentioned titanium (IV) chloride aqueous solution, so that the Ti/Mo (molar ratio) becomes 50 with respect to the Ti component in the above-mentioned titanium(IV) chloride aqueous solution. A precipitate of titanium hydroxide containing tin, molybdenum, and tungsten was obtained by gradually adding 10 mass % of aqueous ammonia added and dissolved so that the molar ratio) became 20, neutralizing and hydrolyzing. The pH at this time was 8. The obtained precipitate was deionized by repeating addition of pure water and decantation. H in the titanium hydroxide precipitate containing tin, molybdenum, and tungsten after this deionization treatment₂O₂35% by mass of hydrogen peroxide is added so that /(Ti+Sn+Mo+W) (molar ratio) becomes 10, and then stirred at 80° C. for 3 hours to fully react, orange-transparent tin, molybdenum, and tungsten A peroxotitanic acid solution (e) was obtained.

Into an autoclave with a volume of 500 mL, 400 mL of a peroxotitanic acid solution (e) containing tin, molybdenum, and tungsten was introduced, and this was hydrothermally treated under conditions of 150° C. for 90 minutes, after which pure water was added to adjust the concentration. Thus, a dispersion (solid content concentration of 1% by mass) of titanium oxide fine particles (E) in which tin, molybdenum, and tungsten were dissolved was obtained. When powder X-ray diffraction measurement of the titanium oxide fine particles (E) was performed, it was found that the observed peak was only that of rutile-type titanium oxide, and that tin, molybdenum, and tungsten were dissolved in the titanium oxide.

By mixing the respective dispersions so that the titanium oxide fine particles (E) and the titanium oxide fine particles (B) are (E): (B) = 70:30 in mass ratio, the visible light responsive photocatalytic titanium oxide fine particle dispersion of the present invention (E- 4) was obtained.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the photocatalyst titanium oxide fine particle dispersion (E-4), and acetaldehyde gas decomposition performance was measured. At 3.9 hours after LED irradiation, 1 ppm (good: ○), the acetaldehyde gas concentration decreased from 8.0 hours to 0.03 ppm (good: ○).

[Example 5]

&lt;Preparation of titanium oxide fine particle dispersion in which tin and vanadium are dissolved&gt;

Tin (IV) chloride is added and dissolved so that Ti/Sn (molar ratio) becomes 20 and vanadyl (IV) sulfate becomes Ti/V (molar ratio) of 2000 in 36 mass % titanium (IV) chloride aqueous solution, and this is pure water After diluting 10-fold with furnace, a precipitate of titanium hydroxide containing tin and vanadium was obtained by gradually adding 10% by mass of aqueous ammonia for neutralization and hydrolysis. The pH of the solution at this time was 8.5. The obtained precipitate was deionized by repeating addition of pure water and decantation. H in the titanium hydroxide precipitate containing tin and vanadium after this deionization treatment₂O₂35 mass % aqueous hydrogen peroxide is added so that /(Ti+Sn+V) (molar ratio) becomes 10, and then stirred at 50° C. for 3 hours to sufficiently react, orange-transparent tin and vanadium-containing peroxotitanic acid solution (f) was obtained.

Into an autoclave with a volume of 500 mL, 400 mL of a tin and vanadium-containing peroxotitanic acid solution (f) is introduced, and this is hydrothermalized for 90 minutes under the conditions of 150 ° C. Then, pure water is added to adjust the concentration by adding tin and A dispersion (solid content concentration of 1% by mass) of titanium oxide fine particles (F) in which vanadium was dissolved was obtained. When powder X-ray diffraction measurement of the titanium oxide fine particles (F) was performed, it was found that the observed peak was only that of rutile titanium oxide, and that tin and vanadium were dissolved in the titanium oxide.

By mixing the respective dispersions so that the titanium oxide fine particles (F) and the titanium oxide fine particles (B) are (F): (B) = 90:10 in mass ratio, the visible light responsive photocatalytic titanium oxide fine particle dispersion of the present invention (E- 5) was obtained.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the photocatalyst titanium oxide fine particle dispersion (E-5), and acetaldehyde gas decomposition performance was measured. After 9.5 hours after LED irradiation, 1 ppm (good: ○), the acetaldehyde gas concentration decreased from 19.2 hours to 0.03 ppm (good: ○).

[Example 6]

&lt;Preparation of titanium oxide fine particle dispersion in which iron and molybdenum are dissolved&gt;

After adding iron (III) chloride so that Ti/Fe (molar ratio) becomes 10 to 36 mass % of an aqueous solution of titanium (IV) chloride, it is diluted 10-fold with pure water, and then molybdenum (VI) oxide is added to the aqueous solution. Titanium hydroxide containing iron and molybdenum by gradually adding 10 mass % of ammonia water added and dissolved so that Ti/Mo (molar ratio) becomes 5 to the Ti component in one titanium (IV) chloride aqueous solution, neutralizing and hydrolyzing it. of the precipitate was obtained. The pH at this time was 8. The obtained precipitate was deionized by repeating addition of pure water and decantation. H in the titanium hydroxide precipitate containing iron and molybdenum after this deionization treatment₂O₂35 mass % aqueous hydrogen peroxide is added so that /(Ti+Fe+Mo) (molar ratio) becomes 8, and then stirred for 2 hours at 50°C to sufficiently react, orange-transparent iron and molybdenum-containing peroxotitanic acid A solution (g) was obtained.

400 mL of iron and molybdenum-containing peroxotitanic acid solution (g) was introduced into an autoclave having a volume of 500 mL, and this was hydrothermally treated for 120 minutes under conditions of 130 ° C. Then, pure water was added to adjust the concentration, A dispersion (solid content concentration of 1% by mass) of titanium oxide fine particles (G) in which iron and molybdenum were dissolved was obtained. When powder X-ray diffraction measurement of the titanium oxide fine particles (G) was performed, it was found that the observed peak was only that of anatase-type titanium oxide, and that iron and molybdenum were dissolved in the titanium oxide.

By mixing the respective dispersions so that the titanium oxide fine particles (A) and the titanium oxide fine particles (G) are (A): (G) = 50:50 in mass ratio, the visible light responsive photocatalytic titanium oxide fine particle dispersion of the present invention (E- 6) was obtained.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the photocatalyst titanium oxide fine particle dispersion (E-6), and the acetaldehyde gas decomposition performance was measured. 1 ppm at 6.5 hours after LED irradiation (good: ○), the acetaldehyde gas concentration decreased from 14.6 hours to 0.03 ppm (good: ○).

[Example 7]

&lt;Preparation of titanium oxide fine particle dispersion in which iron and tungsten are dissolved&gt;

Iron (III) chloride so that Ti/Fe (molar ratio) becomes 6.6, sodium tungsten (VI) oxygen is added so that Ti/W (molar ratio) becomes 10 Except having carried out, it carried out similarly to Example 1, and obtained the dispersion liquid (solid content concentration of 1 mass %) of the titanium oxide microparticles|fine-particles (H) in which iron and tungsten were dissolved. When powder X-ray diffraction measurement of the titanium oxide fine particles (H) was performed, it was found that the observed peak was only that of anatase-type titanium oxide, and that iron and tungsten were dissolved in the titanium oxide.

By mixing the respective dispersions so that the titanium oxide fine particles (E) and the titanium oxide fine particles (H) are (E):(H)=70:30 in mass ratio, the visible light responsive photocatalytic titanium oxide fine particle dispersion of the present invention (E- 7) was obtained.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the photocatalyst titanium oxide fine particle dispersion (E-7), and the acetaldehyde gas decomposition performance was measured. At 3.2 hours after LED irradiation, 1 ppm (good: ○), the acetaldehyde gas concentration decreased from 6.8 hours to 0.03 ppm (good: ○).

[Example 8]

By mixing the respective dispersions so that the titanium oxide fine particles (A), the titanium oxide fine particles (D), and the titanium oxide fine particles (H) are (A):(D):(H)=35:35:30 in mass ratio, this The visible light responsive photocatalyst titanium oxide fine particle dispersion (E-8) of the present invention was obtained.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the photocatalyst titanium oxide fine particle dispersion (E-8), and the acetaldehyde gas decomposition performance was measured. At 4.4 hours after LED irradiation, 1 ppm (good: ○), the acetaldehyde gas concentration decreased from 8.5 hours to 0.03 ppm (good: ○).

[Example 9]

By mixing the respective dispersions so that the titanium oxide fine particles (A), the titanium oxide fine particles (B), and the titanium oxide fine particles (G) are (A):(B):(G)=40:30:30 in mass ratio, this A visible light responsive photocatalyst titanium oxide fine particle dispersion (E-9) of the present invention was obtained.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the photocatalyst titanium oxide fine particle dispersion (E-9), and the acetaldehyde gas decomposition performance was measured. At 9.3 hours after LED irradiation, 1 ppm (good: ○), the acetaldehyde gas concentration decreased from 19.3 hours to 0.03 ppm (good: ○).

[Comparative Example 1]

A titanium oxide fine particle dispersion (C-1) was obtained only from the dispersion liquid of the titanium oxide fine particles (A).

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the titanium oxide fine particle dispersion (C-1), and acetaldehyde gas decomposition performance was measured. The concentration did not decrease (defect: x).

[Comparative Example 2]

A titanium oxide fine particle dispersion (C-2) was obtained only from the dispersion liquid of the titanium oxide fine particles (B).

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the titanium oxide fine particle dispersion (C-2), and acetaldehyde gas decomposition performance was measured. was not observed (defect: ×).

[Comparative Example 3]

&lt;Preparation of titanium oxide fine particle dispersion in which iron is dissolved&gt;

Iron (III) chloride is added to a 36 mass % titanium (IV) chloride aqueous solution so that the Ti/Fe (molar ratio) becomes 10, and this is diluted 10-fold with pure water, and then 10 mass % aqueous ammonia is slowly added to the aqueous solution. A precipitate of titanium hydroxide containing iron was obtained by neutralization and hydrolysis. The pH at this time was 8. The obtained precipitate was deionized by repeating addition of pure water and decantation. H in the iron-containing titanium hydroxide precipitate after this deionization treatment₂O₂35 mass % aqueous hydrogen peroxide was added so that /(Ti+Fe) (molar ratio) was 8, and then stirred at 40°C for 2 hours to sufficiently react to obtain an orange-transparent iron-containing peroxotitanic acid solution (i)..

400 mL of an iron-containing peroxotitanic acid solution (i) is introduced into an autoclave having a volume of 500 mL, hydrothermal treatment is performed for 90 minutes under the conditions of 130° C., and thereafter, pure water is added to adjust the concentration to oxidize iron in solid solution A dispersion liquid (solid content concentration of 1% by mass) of titanium fine particles (I) was obtained. When powder X-ray diffraction measurement of the titanium oxide fine particles (I) was performed, it was found that the observed peak was only that of anatase-type titanium oxide, and that iron was dissolved in the titanium oxide.

A titanium oxide fine particle dispersion (C-3) was obtained only from the dispersion liquid of titanium oxide fine particles (I).

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the titanium oxide fine particle dispersion (C-3), and acetaldehyde gas decomposition performance was measured. was not observed (defect: ×).

[Comparative Example 4]

&lt;Preparation of titanium oxide fine particle dispersion in which copper is dissolved&gt;

Copper (II) chloride is added and dissolved in a 36 mass % titanium (IV) chloride aqueous solution so that Ti/Cu (molar ratio) is 20, diluted 10-fold with pure water, and then 10 mass % aqueous ammonia is gradually added. By neutralization and hydrolysis, a precipitate of titanium hydroxide containing copper was obtained. The pH of the solution at this time was 7.5. The obtained precipitate was deionized by repeating addition of pure water and decantation. In the titanium hydroxide precipitate containing copper after this deionization treatment, H₂O₂35 mass % aqueous hydrogen peroxide was added so that /(Ti+Cu) (molar ratio) became 12, and then stirred at 40°C for 3 hours to sufficiently react to obtain a green transparent copper-containing peroxotitanic acid solution (j)..

400 mL of a copper-containing peroxotitanic acid solution (j) was introduced into an autoclave having a volume of 500 mL, and this was hydrothermalized for 90 minutes under the conditions of 130 ° C. Then, pure water was added to adjust the concentration, whereby copper was dissolved A dispersion (solid content concentration of 1% by mass) of titanium oxide fine particles (J) was obtained. When powder X-ray diffraction measurement was performed, it was found that the observed peak was only that of anatase-type titanium oxide, and copper was dissolved in the titanium oxide.

A titanium oxide fine particle dispersion (C-4) was obtained only from the dispersion liquid of the titanium oxide fine particles (J).

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the titanium oxide fine particle dispersion (C-4), and acetaldehyde gas decomposition performance was measured. was not lowered (defective: ×).

[Comparative Example 5]

A titanium oxide fine particle dispersion (C-5) was obtained by mixing the respective dispersions such that the titanium oxide fine particles (A) and the titanium oxide fine particles (I) were (A):(I)=50:50 in mass ratio.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the titanium oxide fine particle dispersion (C-5), and the acetaldehyde gas decomposition performance was measured., the acetaldehyde gas concentration decreased from 30.5 hours to 0.03 ppm (slightly poor: △).

[Comparative Example 6]

A titanium oxide fine particle dispersion (C-6) was obtained by mixing the respective dispersions so that the titanium oxide fine particles (A) and the titanium oxide fine particles (J) were (A):(J)=70:30 in mass ratio.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the titanium oxide fine particle dispersion (C-6), and acetaldehyde gas decomposition performance was measured. 1 ppm at 17.1 hours after LED irradiation (good: ○), The acetaldehyde gas concentration decreased from 50 hours to 0.2 ppm (defect: x).

[Comparative Example 7]

A titanium oxide fine particle dispersion (C-7) was obtained by mixing the respective dispersions such that the titanium oxide fine particles (D) and the titanium oxide fine particles (I) were (D):(I)=50:50 in mass ratio.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the titanium oxide fine particle dispersion (C-7), and acetaldehyde gas decomposition performance was measured., the acetaldehyde gas concentration decreased from 48.2 hours to 0.03 ppm (somewhat poor: △).

[Comparative Example 8]

&lt;Preparation of tin-dissolved titanium oxide fine particle dispersion&gt;

Tin (IV) chloride is added and dissolved in a 36 mass % titanium (IV) chloride aqueous solution so that Ti/Sn (molar ratio) is 20, diluted 10-fold with pure water, and then 10 mass % aqueous ammonia is gradually added. By neutralization and hydrolysis, a precipitate of titanium hydroxide containing tin was obtained. The pH of the solution at this time was 9. The obtained precipitate was deionized by repeating addition of pure water and decantation. H in the titanium hydroxide precipitate containing tin after this deionization treatment₂O₂35 mass % aqueous hydrogen peroxide was added so that /(Ti+Sn) (molar ratio) might be 6, and after that, it was stirred at room temperature for all day, and it fully reacted, and orange transparent tin containing peroxotitanic acid solution (k) was obtained.

400 mL of a tin-containing peroxotitanic acid solution (k) is introduced into an autoclave having a volume of 500 mL, and this is hydrothermally treated for 90 minutes under conditions of 150 ° C. Then, pure water is added to adjust the concentration, so that tin is dissolved A dispersion liquid (solid content concentration of 1% by mass) of titanium oxide fine particles (K) was obtained. When powder X-ray diffraction measurement of the titanium oxide fine particles (K) was performed, it was found that the observed peak was only that of rutile titanium oxide, and that tin was dissolved in the titanium oxide.

A titanium oxide fine particle dispersion (C-8) was obtained by mixing the respective dispersions so that the titanium oxide fine particles (K) and the titanium oxide fine particles (B) were (K):(B)=70:30 in mass ratio.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the titanium oxide fine particle dispersion (C-8), and the acetaldehyde gas decomposition performance was measured. 1 ppm (defect: ×) at 39.6 hours after LED irradiation, The acetaldehyde gas concentration decreased from 50 hours to 0.9 ppm (defect: x).

[Comparative Example 9]

&lt;Preparation of titanium oxide fine particle dispersion in which molybdenum is dissolved&gt;

After diluting 36% by mass of an aqueous solution of titanium (IV) chloride 10 times with pure water, molybdenum (VI) oxide in the aqueous solution is Ti/Mo (molar ratio) to the Ti component in the aqueous solution of titanium (IV) chloride. A precipitate of titanium hydroxide containing molybdenum was obtained by gradually adding and neutralizing and hydrolyzing 10 mass % aqueous ammonia added and dissolved so that it might become 20. The pH of the solution at this time was 8. The obtained precipitate was deionized by repeating addition of pure water and decantation. H in the titanium hydroxide precipitate containing molybdenum after this deionization treatment₂O₂35% by mass of hydrogen peroxide was added so that /(Ti+Mo) (molar ratio) was 8, and then stirred at room temperature for a full day to fully react, and an orange transparent molybdenum-containing peroxotitanic acid solution (l) was prepared got it

Molybdenum-containing peroxotitanic acid solution (l) 400 mL is introduced into an autoclave with a volume of 500 mL, and this is hydrothermally treated for 120 minutes under the conditions of 130 ° C. Then, pure water is added to adjust the concentration by adding molybdenum. A dispersion (solid content concentration of 1% by mass) of titanium oxide fine particles (L) in which denum was dissolved was obtained. When powder X-ray diffraction measurement of the titanium oxide fine particles (L) was performed, it was found that the observed peak was only that of anatase-type titanium oxide, and that molybdenum was dissolved in the titanium oxide.

A titanium oxide fine particle dispersion (C-9) was obtained by mixing the respective dispersions so that the titanium oxide fine particles (L) and the titanium oxide fine particles (B) were (L):(B)=50:50 in mass ratio.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the titanium oxide fine particle dispersion (C-9), and acetaldehyde gas decomposition performance was measured. The concentration did not decrease (defect: x).

[Comparative Example 10]

&lt;Preparation of titanium oxide fine particle dispersion&gt;

After diluting 36 mass % of titanium (IV) chloride aqueous solution 10-fold with pure water, 10 mass % aqueous ammonia was gradually added, neutralization and hydrolysis were carried out, and the precipitate of titanium hydroxide was obtained. The pH of the solution at this time was 9. The obtained precipitate was deionized by repeating addition of pure water and decantation. H in the titanium hydroxide precipitate after this deionization treatment₂O₂35 mass % aqueous hydrogen peroxide was added so that /Ti (molar ratio) might become 5, and after that, it stirred at room temperature for all day, and it fully reacted, and the yellow transparent peroxotitanic acid solution (m) was obtained.

Into an autoclave having a volume of 500 mL, 400 mL of a peroxotitanic acid solution (m) is introduced, and this is hydrothermal treatment for 90 minutes under the conditions of 130 ° C. Then, by adding pure water to adjust the concentration, titanium oxide fine particles (M) A dispersion liquid (solid content concentration of 1% by mass) was obtained. When powder X-ray diffraction measurement of the titanium oxide fine particles (M) was performed, the observed peak was that of anatase-type titanium oxide.

A titanium oxide fine particle dispersion (C-10) was obtained only from the dispersion liquid of the titanium oxide fine particles (M).

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the titanium oxide fine particle dispersion (C-10), and acetaldehyde gas decomposition performance was measured. was not observed (defect: ×).

[Comparative Example 11]

&lt;Recovery of dissolved components from dispersion of titanium oxide fine particles in which iron is dissolved&gt;

By centrifuging the dispersion of titanium oxide fine particles (I) in which iron is dissolved therein at 210,000 × g with a small ultracentrifuge (trade name "himac CS150NX", manufactured by Hitachi Koki Co., Ltd.), titanium oxide fine particles in which iron is dissolved (I) and a solvent and a dissolved component. The concentration of the dissolved iron component in the solvent was measured with an ICP emission spectrometer (trade name: "ICP emission spectrometer IRIS 1000", Thermo Fisher Scientific Co., Ltd.), and it was 2.2 ppm, and most of the added iron component was dissolved in the titanium oxide fine particles. It was found that there was an insoluble component.

Titanium oxide fine particles (A), a solvent and a dissolved component obtained by separating the titanium oxide fine particle (I) from the dispersion of the titanium oxide fine particle (I) by an ultracentrifuge are (A): (I dissolved component) = 50:50 Titanium oxide fine particle dispersion (C-11) was obtained by mixing each dispersion liquid, a solvent, and a dissolution component as much as possible.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the titanium oxide fine particle dispersion (C-11), and the acetaldehyde gas decomposition performance was measured.), the acetaldehyde gas concentration did not decrease.

[Comparative Example 12]

&lt;Preparation of titanium oxide fine particle dispersion with iron component adsorbed (= supported) on the surface&gt;

An iron component by mixing the dispersion of the titanium oxide fine particles (A) and an aqueous iron (III) chloride solution in which iron (III) chloride is dissolved to 1% by mass with pure water so that the mass ratio of the titanium oxide fine particles (A) and iron is 100:0.05. A titanium oxide fine particle dispersion (C-12) adsorbed on the surface was obtained.

Hereinafter, in the same manner as in Example 1, a coating solution for evaluation and a photocatalyst thin film were prepared from the titanium oxide fine particle dispersion (C-12), and the acetaldehyde gas decomposition performance was measured., the acetaldehyde gas concentration decreased from 50 hours to 0.8 ppm (defect: ×).

[Comparative Example 13]

&lt;Preparation of titanium oxide fine particle dispersion with iron component adsorbed (= supported) on the surface&gt;

The dispersion of titanium oxide fine particles (A) and an aqueous iron (III) chloride solution in which iron (III) chloride is dissolved to 1% by mass with pure water were mixed so that the mass ratio of titanium oxide fine particles (A) and iron was 100:0.5, and the dispersion (C Since the titanium oxide fine particles in -13) aggregated and precipitated, evaluation was stopped. This method of adding the iron group compound to the dispersion deteriorates the dispersed state of the titanium oxide fine particles in the dispersion, so there is a problem in that the addition amount is limited to a very small amount, and the stability of the solution is also deteriorated.

Table 1 shows the raw material ratio of the titanium oxide fine particles used in Examples 1 to 9 and Comparative Examples 1 to 13, hydrothermal treatment conditions, and average particle diameter (D₅₀) are summarized and shown.

<tables num="1"><img file="KR102436684B1_D0001.tif" /></tables>

Table 2 summarizes the mixing ratio, average particle diameter, and acetaldehyde gas decomposition test results of the dispersions of visible light responsive photocatalyst fine particles of Examples 1 to 9 and Comparative Examples 1 to 13.

<tables num="2"><img file="KR102436684B1_D0002.tif" /></tables>

As can be seen from the results of Examples 1 to 9, the first titanium oxide fine particles in which a tin component and a transition metal component (molybdenum component, tungsten component, vanadium component) that enhance the visible light responsiveness are dissolved, an iron group component and By mixing the second titanium oxide fine particles in which the chromium group component is dissolved, the decomposition of acetaldehyde gas is improved even under LED irradiation, which emits only light in the visible region even with a small amount of photocatalyst, and the indoor air regulated by the Japanese Ministry of Health, Labor and Welfare It is possible to reduce the acetaldehyde gas concentration to 0.03 ppm or less, which is the indoor concentration guide value (acetaldehyde) of heavy chemical substances, within an effective time, for example, within 50 hours, and preferably within 20 hours.

As can be seen from the results of Comparative Examples 1 and 2, the first titanium oxide fine particles and the second titanium oxide fine particles do not have sufficient photocatalytic activity under visible light irradiation alone, respectively.

As can be seen from the results of Comparative Examples 2, 3, 4, and 10, titanium oxide fine particles in which iron is dissolved, titanium oxide fine particles in which iron and a chromium group component (tungsten) are dissolved in solid solution, titanium oxide fine particles in which copper is dissolved, and When titanium oxide fine particles in which dissimilar metals are not dissolved at all are used alone, no activity is obtained under visible light irradiation. This is a behavior different from the case where the titanium oxide particle which made copper solid solution was used alone.

As can be seen from the results of Comparative Examples 5 and 7, when only iron is selected as the metal dissolved in the second titanium oxide fine particles, as the metal dissolved in the second titanium oxide fine particles shown in each example of Examples, iron and chromium group components It can be seen that the time taken for decomposition of acetaldehyde gas is long, and the photocatalytic activity is low compared to the case where both of these are selected.

As can be seen from the results of Comparative Example 6, when copper is selected as the metal dissolved in the second titanium oxide fine particles, it is decomposed under visible light at the initial stage when the acetaldehyde gas concentration is high, but is a sufficient photocatalyst for the low concentration acetaldehyde gas. No activity is obtained. On the other hand, as shown in each example of the Examples, when the iron group component and the chromium group component are selected as the metals dissolved in the second titanium oxide fine particles, not only a fast decomposition rate is obtained when the acetaldehyde gas concentration is high, but also acetaldehyde Activity was obtained even when the gas concentration was low, and the result was obtained that it could be reduced to 0.03 ppm or less.

As can be seen from the results of Comparative Examples 8 and 9, when the metal dissolved in the first titanium oxide fine particles is either tin or a transition metal, sufficient photocatalytic activity under irradiation with visible light cannot be obtained. Therefore, in order to obtain high activity under visible light irradiation, it is necessary to add tin and a transition metal component that enhances the visible light responsiveness to the first titanium oxide fine particles.

As can be seen from the results of Comparative Example 11, the second titanium oxide fine particles are essential for improving the visible light activity, and the iron component that is not dissolved in the second titanium oxide fine particles and is dissolved in the dispersion does not contribute to the improvement of the activity.. That is, the main cause of the visible light activity improvement effect is not the iron component leaking from the second titanium oxide fine particles, but the second titanium oxide fine particles in which the iron group component and the chromium group component are solid-dissolved, and the transition metal component that enhances the visible light responsiveness with tin. It is by the combination of the 1st titanium oxide microparticles|fine-particles.

Further, as can be seen from the results of Comparative Examples 12 and 13, the dissolved iron component contributes to the improvement of visible light activity to some extent, but sufficient visible light activity with respect to low concentration acetaldehyde gas is not obtained. Moreover, when added in a large amount, there is a possibility that aggregation and precipitation of the titanium oxide fine particles in the dispersion may be caused.

(Industrial availability)

The visible light responsive photocatalyst fine particle dispersion of the present invention is useful for preparing a photocatalyst thin film by applying it to various substrates made of an inorganic material such as glass and metal and an organic material such as a polymer film (PET film, etc.), especially on a polymer film It is useful for producing a transparent photocatalyst thin film.