JP6721742B2 - Interior material manufacturing method - Google Patents

Description

Embodiments of the present invention relate to a method of manufacturing an interior material.

Titanium oxide is known as a photocatalyst material used for antifouling and deodorizing purposes. Photocatalytic materials are used in various fields such as outdoor and indoor building materials, home appliances such as lighting devices, air purifiers, air conditioners, toilet bowls, washbasins, mirrors, bathrooms, and the like. However, since titanium oxide is excited in the ultraviolet light region, sufficient photocatalytic performance cannot be obtained indoors with little ultraviolet light. Therefore, research and development of visible-light-responsive photocatalysts that exhibit photocatalytic performance even under visible light are under way. Further, in order to improve the photocatalytic performance of ultraviolet light responsive titanium oxide with visible light, it has been studied to dope the titanium oxide with nitrogen or sulfur or to carry another metal.

Tungsten oxide is known as a visible light responsive photocatalyst. The photocatalyst film using tungsten oxide is formed, for example, by applying a dispersion liquid containing tungsten oxide fine particles to the surface of a base material of a product to which photocatalytic performance is imparted. Examples of the photocatalyst dispersion liquid include an aqueous dispersion liquid in which tungsten oxide fine particles having an average primary particle diameter (D50) in the range of 1 to 400 nm are dispersed in water or the like so that the pH is in the range of 1.5 to 6.5. Are known. With such an aqueous dispersion, the dispersibility of the tungsten oxide fine particles is enhanced, and the formability of the film containing the tungsten oxide fine particles is improved. Therefore, it is possible to obtain a photocatalytic film capable of stably exhibiting the photocatalytic performance of the tungsten oxide fine particles.

Since the photocatalytic activity of titanium oxide having improved visible light response performance is proportional to the light amount, sufficient photocatalytic performance cannot be obtained with the light amount according to the illuminance of indoor lighting (several lx to 3000 lx). Therefore, in the living space where the application of the photocatalyst is expected, the effect can be obtained only in the vicinity of or directly under the illumination light source. A conventional photocatalytic film containing tungsten oxide fine particles exhibits a gas decomposition rate of 5% or more under an environment where the illuminance of visible light is about 2000 lx, for example. However, considering the practicality of the photocatalyst film, the decomposition performance of harmful gas such as acetaldehyde is not always sufficient, and therefore improvement of the gas decomposition performance under low illuminance is required. Further, the conventional photocatalytic film containing tungsten oxide fine particles has a problem that the gas decomposition rate becomes slow in an environment where the gas concentration is low because the gas adsorption force is weak. For this reason, it is required to improve the gas resolution by the visible light responsive photocatalyst.

International Publication No. 2008/117655 International Publication No. 2009/031317 International Publication No. 2009/110234

The problem to be solved by the present invention is an interior equipped with a photocatalyst capable of exhibiting good photocatalytic performance such as good gas resolution even in an environment where the illuminance of visible light is low or in an environment where the gas concentration is low. It is to provide a method for manufacturing a material.

The method for producing an interior material according to the embodiment is a method for producing an interior material in which a photocatalyst is adhered onto a base material made of at least one selected from glass, ceramics, plastic, resin, paper, fiber, metal, and wood. A step of dispersing a photocatalyst in an aqueous dispersion medium to obtain a photocatalyst dispersion, a step of mixing the photocatalyst dispersion and at least one binder component selected from an inorganic binder and an organic binder to obtain a coating, A step of depositing a coating material on the base material, wherein the photocatalyst body comprises tungsten oxide-based fine particles containing tungsten oxide in a range of 5% by mass or more and 100% by mass or less, and Raman spectroscopy of the photocatalyst body is performed. in the Raman spectrum by law, the ratio of the intensity X of peaks observed in the range of 920 cm ^-1 or more 950 cm ^-1 or less with respect to the peak intensity Y observed in a range of 800 cm ^-1 or more 810 cm ^-1 or less (X / Y) Is 0.001 or more and 0.035 or less.

It is a figure which shows the Raman spectrum of sample A (comparative example), sample D (example), and sample F (comparative example) in the example of manufacture of tungsten oxide fine particles.

Hereinafter, modes for carrying out the photocatalyst body, the photocatalyst dispersion liquid, the photocatalyst coating material, the photocatalyst film, and the product of the present invention will be described.

(Photocatalyst)
The photocatalyst body of the embodiment includes tungsten oxide-based fine particles containing tungsten oxide in the range of 5 to 100 mass %. Examples of the tungsten oxide-based fine particles that constitute the photocatalyst include single particles of tungsten oxide, and fine particles such as a mixture or complex of tungsten oxide and another metal element. In the photocatalyst body of the embodiment, the content of tungsten oxide is in the range of 5 to 100% by mass. If the content of tungsten oxide is less than 5% by mass, the visible light responsive photocatalytic performance based on the tungsten oxide fine particles cannot be sufficiently obtained. The content of tungsten oxide is preferably 45% by mass or more.

The photocatalyst body of the embodiment may contain a metal element other than tungsten (hereinafter referred to as an added metal element). Examples of the metal element contained in the photocatalyst body include transition metal elements other than tungsten, zinc group elements such as zinc, and earth metal elements such as aluminum. The transition metal element is an element having an atomic number of 21 to 29, 39 to 47, 57 to 79, 89 to 109, and among these, a metal element other than tungsten (atomic number 74) can be contained in the photocatalyst body. .. Zinc group elements are elements with atomic numbers 30, 48 and 80, and earth metal elements are elements with atomic numbers 13, 31, 49 and 81. You may make these photocatalyst bodies contain these metal elements. By incorporating the metal element in the photocatalyst in an appropriate amount, the visible light responsive photocatalytic performance of the photocatalyst can be improved.

The content of the added metal element in the photocatalyst body is preferably in the range of 0.001 to 50 mass %. If the content of the added metal element is less than 0.001% by mass, the effect of improving the photocatalytic performance cannot be sufficiently obtained. When the content of the added metal element exceeds 50% by mass, the content of the tungsten oxide is relatively decreased, which may deteriorate the photocatalytic performance based on the fine particles of tungsten oxide. The content of the added metal element is more preferably in the range of 0.005 to 10 mass %. By including the additional metal element in the photocatalyst body in such a range, the photocatalytic performance of the photocatalyst body of the embodiment can be effectively improved.

The metal element (additional metal element) contained in the photocatalyst body is titanium (Ti), zirconium (Zr), manganese (Mn), iron (Fe), ruthenium (Ru), nickel (Ni), palladium (Pd), platinum. At least one selected from (Pt), copper (Cu), silver (Ag), cerium (Ce), and aluminum (Al) is preferable. By including these metal elements in the photocatalyst in the range of 0.005 to 10 mass %, the photocatalytic performance of the photocatalyst of the embodiment can be more effectively improved.

A metal oxide is mentioned as a typical example of the existence form of the addition metal element in a photocatalyst. The photocatalyst body preferably contains an oxide of an additional metal element in addition to tungsten oxide. The content of the oxide of the added metal element in the photocatalyst is preferably in the range of 0.01 to 70% by mass. By including the oxide of the additional metal element in the photocatalyst within such a range, the photocatalytic performance of the photocatalyst can be further improved. More preferably, the oxide of the additional metal element is at least one selected from zirconium oxide, titanium oxide, and ruthenium oxide. By including such a metal oxide in the photocatalyst, the photocatalytic performance can be more effectively improved. The content of metal oxides other than tungsten oxide in the photocatalyst is more preferably in the range of 0.02 to 55 mass %.

In the photocatalyst body of the embodiment, the added metal element can be contained in various forms. The photocatalyst body can contain the additional metal element as a simple substance of the additional metal element, a compound such as an oxide, a complex compound with tungsten oxide, or the like. The additive metal element may form a composite oxide with two or more kinds of metal elements. Further, the simple substance or the compound of the added metal element may be supported on the tungsten oxide. Alternatively, tungsten oxide may be supported on a compound of an additive metal element or the like.

Specific examples of the tungsten oxide-based fine particles containing the added metal element include a mixture of the tungsten oxide fine particles and the fine particles of the added metal element (fine particles of the metal), the fine particles of the compound, and the like; Mixture fine particles, alloy fine particles of tungsten oxide and additional metal element simple substance or compound, etc., composite compound fine particles of tungsten oxide and additional metal element simple substance or compound, tungsten oxide and additional metal element simple substance or compound, etc. Examples include carrier fine particles. These fine particles are examples of tungsten oxide-based fine particles, and the photocatalyst body of the embodiment is not limited thereto.

In the case where the photocatalyst body of the embodiment contains the additive metal element, the method of combining tungsten oxide and the additive metal element is not particularly limited. When mixing or compounding tungsten oxide and the additive metal element, a method of mixing the tungsten oxide powder and a simple substance powder (metal powder) or a compound powder (for example, a metal oxide powder) of the additive metal element, at least one of which is a solution or dispersion. Various mixing methods such as a method of mixing as a liquid or a sol, an impregnation method, a supporting method, or a composite method can be applied. For example, when the metal oxide to be added is zirconium oxide, various shapes of zirconium oxide can be applied, but the primary particles are preferably rod-shaped. It is preferable to mix a zirconium oxide sol having particles in which rod-shaped primary particles are aggregated with tungsten oxide fine particles or a dispersion liquid in which the fine particles are dispersed in water or the like.

The photocatalyst body of the embodiment may contain a metal element or the like as a trace amount of impurities. The content of the metal element as the impurity element is preferably 2% by mass or less. Examples of the impurity metal element include an element generally contained in tungsten ore and a contaminant element that is mixed when manufacturing a tungsten compound used as a raw material. Examples of the impurity metal element include Fe, Mo, Mn, Cu, Ti, Al, Ca, Ni, Cr, and Mg. However, this is not the case when these elements are used as additional metal elements.

The photocatalyst body of the embodiment has the following characteristics when the fine structure such as crystallinity and surface state is analyzed by Raman spectroscopy. In the Raman spectra as a result of measurement by Raman spectroscopy photocatalyst, with respect to the intensity Y of the peaks observed in the range of 800～810Cm ^-1, the intensity X of peaks observed in the range of 920～950Cm ^-1 The ratio (X/Y) is in the range of 0<X/Y≦0.04. When the photocatalyst has such a Raman peak intensity ratio (X/Y), the photocatalyst performance such as the gas resolution of the photocatalyst based on the tungsten oxide fine particles can be improved. Specifically, it becomes possible to obtain good photocatalytic performance such as gas resolution even under an environment where the illuminance of visible light is low or an environment where the gas concentration is low.

That is, the tungsten oxide fine particles exhibit photocatalytic performance such as gas decomposing ability under the irradiation of visible light. However, in an environment where the illuminance of visible light is low, the photocatalytic performance of tungsten oxide cannot be fully exhibited. Furthermore, the decomposition rate of tungsten oxide becomes slower as the gas concentration decreases from the initial concentration. It is considered that this is because the decomposition performance of tungsten oxide with respect to an intermediate substance generated at the time of decomposition of gas is low, and the gas adsorbing power of tungsten oxide is low under a low gas concentration environment. In order to improve the gas resolving power of tungsten oxide under the irradiation of visible light of low illuminance, the decomposition performance of the intermediate substance of tungsten oxide and the adsorbing power of gas under low concentration, the inventors of the present invention have a peak intensity ratio of Raman spectrum. It has been found that setting (X/Y) in the range of 0<X/Y≦0.04 is effective.

The peak intensity ratio (X/Y) in the Raman spectrum represents the crystallinity of tungsten oxide-based fine particles, the state of surface defects, and the like. By controlling the peak intensity ratio (X/Y) to more than 0 and 0.04 or less, the photocatalytic activity of the photocatalyst (tungsten oxide-based fine particles) can be effectively increased. When the peak intensity ratio (X/Y) is zero, the crystallinity of the tungsten oxide fine particles is improved, but it is considered that the surface of the tungsten oxide fine particles has almost no oxygen defects. In such a state, high gas resolution cannot be obtained. The peak intensity ratio (X/Y) is more preferably 0.001 or more. When the peak intensity ratio (X/Y) exceeds 0.04, the amount of surface defects such as oxygen defects increases excessively, and the photocatalytic activity decreases conversely, so that high gas decomposition performance cannot be obtained. The peak intensity ratio (X/Y) is more preferably 0.03 or less.

When the Raman peak intensity ratio (X/Y) of the photocatalyst is in the range of more than 0 and 0.04 or less, the crystalline state or surface state (existence degree of surface defects) of the tungsten oxide-based fine particles is used as a photocatalyst. It can be controlled to a suitable state. Therefore, the gas decomposition performance of the tungsten oxide-based fine particles under visible light with low illuminance can be improved. Further, the decomposition performance of the intermediate substance and the gas adsorption power by the tungsten oxide-based fine particles in a state where the gas concentration is low can be enhanced. According to the photocatalyst body of the embodiment, it is possible to exhibit high gas decomposition performance even in an environment where the illuminance of visible light is low or an environment where the gas concentration is low. In addition, the photocatalyst body of the embodiment exhibits gas decomposition performance even under an irradiation environment of ultraviolet light. According to the photocatalyst body of the embodiment, the gas decomposition performance can be exhibited under a wider range of conditions than the conventional photocatalyst body. These make it possible to provide a photocatalyst body with improved practicality.

The Raman peak intensity ratio (X/Y) of the photocatalyst described above can be obtained by controlling the heat treatment conditions, such as the heat treatment atmosphere and the heat treatment temperature, performed after the tungsten oxide-based fine particles are produced. Furthermore, since the surface state of the tungsten oxide-based fine particles changes depending on the environmental temperature and the like in the storage state, the Raman peak intensity ratio (X/Y) is maintained in an appropriate range by adjusting these conditions. .. As described in detail later, the temperature of the heat treatment performed after the production of the tungsten oxide-based fine particles is preferably in the range of 200 to 800°C. Furthermore, in order to adjust the crystallinity and surface state of the tungsten oxide-based fine particles to an appropriate state, it is preferable to control the temperature rising rate and the temperature falling rate during the heat treatment.

Regarding the crystallinity of tungsten oxide, the higher the crystallinity, the more improved the photocatalytic performance. However, when the heat treatment is performed under the condition that the crystallinity of the tungsten oxide is excessively increased, the tungsten oxide grains grow and the specific surface area of the fine particles becomes small. Further, if the crystallinity of tungsten oxide is increased too much, the surface of the fine particles will be in a state where there are almost no surface defects such as oxygen vacancies. These are factors that reduce the photocatalytic performance of the photocatalyst body. Even when such a point is taken into consideration, by controlling the Raman peak intensity ratio (X/Y) of the photocatalyst to a range of more than 0 and 0.04 or less, the crystallinity of tungsten oxide, The surface condition and particle size are adjusted to an appropriate condition. Therefore, it becomes possible to provide a photocatalyst having excellent photocatalytic performance such as gas decomposing ability and further improved practicality.

In the tungsten oxide-based fine particles constituting the photocatalyst of the embodiment, the peak intensity ratio (X/Y) of the Raman spectrum is more than 0 and 0.04 or less, and the Raman spectrum of the photocatalyst is 268. A first peak existing in the range of ˜274 cm ⁻¹ (peak having the largest peak intensity ratio), a second peak existing in the range of 630 to 720 cm ⁻¹ (peak having the second largest peak intensity ratio), and It is preferable to have the third peak (peak having the third largest peak intensity ratio) existing in the range of 800 to 810 cm ⁻¹ .

Furthermore, the half-value width of the first peak is preferably within the range of 8 to 25 cm ⁻¹ . The full width at half maximum of the second peak is preferably in the range of 15 to 75 cm ^{−1, and} the full width at half maximum of the third peak is preferably in the range of 15 to 50 cm ⁻¹ . These Raman peaks show that the crystal of tungsten oxide has a crystal structure containing at least one selected from monoclinic crystal, triclinic crystal, and orthorhombic crystal, and among them, particularly in visible light responsive photocatalysts. It shows that the crystal structure is suitable. The tungsten oxide-based fine particles having such a crystal structure can stably exhibit excellent photocatalytic performance.

The Raman spectrum in the embodiment is to be measured under the conditions of a temperature of 20 to 30° C. and a humidity of 30 to 70% using an Ar ion laser having a wavelength of 514.5 nm. Regarding the peak intensity of the Raman spectrum, the peak intensity X has a straight line drawn to the spectral value of 900 cm ^{−1 and} the spectral value of 1000 cm ⁻¹ as a zero point, and the peak intensity Y has a spectral value of 1000 cm ⁻¹ as a zero point. Intensity from them to the peak apex. Specifically, to measure the intensity X to the vertex of the maximum peak present in the range of 920～950Cm ^-1, and intensity Y to the vertex of the maximum peak present in the range of 800～810Cm ^-1, these strength The peak intensity ratio (X/Y) is calculated from X and intensity Y.

It is preferable that the tungsten oxide constituting the photocatalyst body is mainly made of WO ₃ (tungsten trioxide). It is preferable that the tungsten oxide substantially consists of WO _3, but other tungsten oxides (WO ₂ , WO, W ₂ O ₃ , and W ₂ ) may be used as long as the peak intensity ratio (X/Y) of the Raman spectrum is satisfied. ₄ O ₅ , W ₄ O _11, etc.) may be contained. The average particle diameter (D50) of the tungsten oxide-based fine particles is preferably 1 nm or more and 30 μm or less. The average particle diameter (D50) of the tungsten oxide-based fine particles is more preferably 50 nm or more and 1 μm or less. In the particle size distribution of the tungsten oxide-based fine particles, the D90 diameter is preferably 0.05 to 10 μm. BET specific surface area of the tungsten oxide based particles is preferably from 4.1~820m ² / g, more preferably from 10 to 300 m ² / g.

The photocatalyst dispersion liquid is prepared by mixing the tungsten oxide-based fine particles with an aqueous dispersion medium as described later and subjecting this to a dispersion treatment with an ultrasonic disperser, a wet jet mill, a bead mill or the like. In the photocatalyst dispersion liquid thus obtained, the photocatalyst body including the tungsten oxide-based fine particles contains aggregated particles in which primary particles are aggregated. The particle size distribution including the agglomerated particles is measured by a wet type laser diffraction type particle size distribution meter, etc., and when the D50 diameter in the volume-based integrated diameter is 1 nm or more and 30 μm or less, a good dispersion state and a uniform and stable film-forming property are obtained. Can be obtained, and as a result, high photocatalytic performance can be obtained.

If the D50 diameter of the tungsten oxide-based fine particles exceeds 30 μm, sufficient characteristics cannot be obtained as a photocatalyst dispersion liquid. When the D50 diameter of the tungsten oxide-based fine particles is smaller than 1 nm, the particles are too small and the photocatalyst body is inferior in handleability, and the practicality of the photocatalyst body and the dispersion liquid using the same deteriorates. Furthermore, when the D90 diameter of the tungsten oxide-based fine particles is less than 0.05 μm, the dispersibility of the tungsten oxide-based fine particles decreases. Therefore, it becomes difficult to obtain a uniform dispersion liquid or coating material. When the D90 diameter exceeds 10 μm, it becomes difficult to form a uniform and stable film using a dispersion liquid or a coating material, and the photocatalytic performance cannot be sufficiently exhibited. Further, in order to enhance the photocatalytic performance when the photocatalyst is formed into a film, it is preferable that the fine particles are not excessively strained during the dispersion treatment when the dispersion is prepared.

When the color of the photocatalyst of the embodiment is represented by the L*a*b* color system (Elster/Aster/Beast color system), a* is 10 or less, b* is -5 or more, and L It is preferable that * has a body color of 50 or more. The L*a*b* color system is a method used to represent an object color, standardized by the International Commission on Illumination (CIE) in 1976, and specified in JIS Z-8729 in Japan. By forming a photocatalyst film using a photocatalyst having such a color and a dispersion liquid in which it is dispersed in an aqueous dispersion medium, not only good photocatalytic performance is obtained, but also the color tone of the substrate is impaired. There is no. Therefore, in addition to the original characteristics and quality of the product having the photocatalytic film, it becomes possible to stably exhibit the photocatalytic performance based on the photocatalytic film.

The tungsten oxide fine particles mainly constituting the photocatalyst body of the embodiment are preferably produced by the method described below. However, the method for producing the tungsten oxide-based fine particles is not particularly limited. The tungsten oxide-based fine particles are preferably produced by applying a sublimation process. Furthermore, it is preferable to combine a heat treatment step with the sublimation step. According to the tungsten oxide-based fine particles produced by such a method, the above-described Raman peak intensity ratio (X/Y) and the crystal state, crystal structure, average particle diameter and the like based on the intensity ratio can be stably realized.

First, the sublimation process will be described. The sublimation step is a step of obtaining tungsten oxide fine particles by sublimating a metal tungsten powder, a tungsten compound powder, or a tungsten compound solution in an oxygen atmosphere. Sublimation is a phenomenon in which a solid phase changes to a gas phase or a gas phase changes to a solid phase without passing through a liquid phase. By oxidizing metallic tungsten powder, a tungsten compound powder, or a tungsten compound solution as a raw material while sublimating, tungsten oxide in a fine particle state can be obtained.

As the raw material (tungsten raw material) for the sublimation step, any of metal tungsten powder, tungsten compound powder, or tungsten compound solution may be used. Examples of the tungsten compound used as a raw material include tungsten trioxide (WO ₃ ), tungsten dioxide (WO ₂ ), tungsten oxide such as lower oxide, tungsten carbide, ammonium tungstate, calcium tungstate, tungstic acid, and the like. ..

By performing the sublimation step of the tungsten raw material as described above in an oxygen atmosphere, the metallic tungsten powder or the tungsten compound powder is instantly changed from the solid phase to the vapor phase, and further, the vaporized metallic tungsten vapor is oxidized, Fine particles of tungsten oxide are obtained. Even when a solution is used, it becomes a gas phase through the tungsten oxide or compound. Thus, the tungsten oxide fine particles can be obtained by utilizing the oxidation reaction in the gas phase. Furthermore, the crystal structure of the tungsten oxide fine particles can be controlled.

As a raw material for the sublimation step, at least 1 selected from metallic tungsten powder, tungsten oxide powder, tungsten carbide powder, and ammonium tungstate powder because impurities are hardly contained in tungsten oxide fine particles obtained by sublimation in an oxygen atmosphere. It is preferred to use seeds. Metallic tungsten powder and tungsten oxide powder are particularly preferable as a raw material in the sublimation process because they do not contain harmful substances as by-products (substances other than tungsten oxide) formed in the sublimation process.

As a tungsten compound used as a raw material, a compound containing tungsten (W) and oxygen (O) as its constituent elements is preferable. When W and O are included as constituent components, sublimation is likely to occur instantaneously when an inductively coupled plasma treatment or the like described later is applied in the sublimation step. Examples of such a tungsten compound include WO ₃ , W ₂₀ O ₅₈ , W ₁₈ O ₄₉ , WO _{2 and the} like. Further, a solution or salt of tungstic acid, ammonium paratungstate, ammonium metatungstate is also effective.

In the case of producing composite fine particles of tungsten oxide and a simple substance or compound of an additive metal element, in addition to the tungsten raw material, a metal element such as a transition metal element or an earth metal element, a compound containing a metal or an oxide. Alternatively, they may be mixed in the form of a complex compound or the like. By treating tungsten oxide at the same time as another metal element, it is possible to obtain composite compound fine particles such as a composite oxide of tungsten oxide and another metal element. The composite fine particles can also be obtained by mixing and supporting tungsten oxide fine particles with simple particles or compound particles of another metal element. The composite method of tungsten oxide and another metal element is not particularly limited, and various known methods can be applied.

The metal tungsten powder or the tungsten compound powder as the tungsten raw material preferably has an average particle diameter in the range of 0.1 to 100 μm. The average particle diameter of the tungsten raw material is more preferably in the range of 0.3 μm to 10 μm, further preferably in the range of 0.3 μm to 3 μm, and preferably in the range of 0.3 μm to 1.5 μm. When a metal tungsten powder or a tungsten compound powder having an average particle diameter within the above range is used, sublimation easily occurs. When the average particle diameter of the tungsten raw material is less than 0.1 μm, the raw material powder is too fine, which requires pre-conditioning of the raw material powder, lowers the handling property, and is expensive, which is industrial. Not good for When the average particle size of the tungsten raw material exceeds 100 μm, it is difficult to cause a uniform sublimation reaction. Even if the average particle diameter is large, a uniform sublimation reaction can be caused by treating with a large amount of energy, but it is not industrially preferable.

Examples of the method of sublimating the tungsten raw material in the oxygen atmosphere in the sublimation step include at least one treatment selected from inductively coupled plasma treatment, arc discharge treatment, laser treatment, electron beam treatment, and gas burner treatment. Among these, in laser processing and electron beam processing, a sublimation process is performed by irradiating a laser or an electron beam. Since the irradiation spot diameter of laser and electron beam is small, it takes time to process a large amount of raw material at one time, but there is an advantage that it is not necessary to strictly control the particle diameter of the raw material powder and the stability of the supply amount. ..

Inductively coupled plasma treatment or arc discharge treatment requires adjustment of the plasma or arc discharge generation region, but a large amount of raw material powder can be oxidized at a time in an oxygen atmosphere. Also, the amount of raw material that can be processed at one time can be controlled. Although the gas burner treatment has a relatively low power cost, it is difficult to process a large amount of raw material powder or raw material solution. Therefore, the gas burner process is inferior in productivity. The gas burner process is not particularly limited as long as it has sufficient energy for sublimation. A propane gas burner, an acetylene gas burner, or the like is used.

When the inductively coupled plasma treatment is applied to the sublimation process, a method is usually used in which plasma is generated using argon gas or oxygen gas and metallic tungsten powder or tungsten compound powder is supplied into this plasma. As a method of supplying the tungsten raw material into the plasma, for example, a method of blowing a metal tungsten powder or a tungsten compound powder together with a carrier gas, a method of blowing a dispersion liquid in which the metal tungsten powder or the tungsten compound powder is dispersed in a predetermined liquid dispersion medium. Etc.

Examples of the carrier gas used when blowing the metal tungsten powder or the tungsten compound powder into the plasma include air, oxygen, and an inert gas containing oxygen. Of these, air is preferably used because of its low cost. Inert oxygen such as argon or helium as the carrier gas when oxygen is sufficiently contained in the reaction field, such as when a reaction gas containing oxygen is introduced in addition to the carrier gas, or when the tungsten compound powder is tungsten oxide. Gas may be used. It is preferable to use oxygen or an inert gas containing oxygen as the reaction gas. When an inert gas containing oxygen is used, it is preferable to set the amount of oxygen so that the amount of oxygen required for the oxidation reaction can be sufficiently supplied.

The crystal structure of the tungsten oxide fine particles can be easily controlled by applying the method of blowing the metal tungsten powder or the tungsten compound powder together with the carrier gas, and adjusting the gas flow rate, the pressure in the reaction container, and the like. Specifically, at least one selected from monoclinic and triclinic (monoclinic, triclinic, or a mixed crystal of monoclinic and triclinic), or an orthorhombic mixture thereof. Tungsten oxide fine particles having a crystal structure are easily obtained. The crystal structure of the tungsten oxide fine particles has a crystal structure in which monoclinic crystals and triclinic crystals are mixed, a crystal structure in which monoclinic crystals and orthorhombic crystals are mixed, a crystal structure in which triclinic crystals and orthorhombic crystals are mixed, It preferably has any one of crystal structures in which monoclinic crystals, triclinic crystals and orthorhombic crystals are mixed.

Examples of the dispersion medium used for preparing the dispersion liquid of the metal tungsten powder or the tungsten compound powder include a liquid dispersion medium having oxygen atoms in its molecule. The use of the dispersion liquid facilitates the handling of the raw material powder. As the liquid dispersion medium having oxygen atoms in the molecule, for example, one containing at least 20% by volume of at least one selected from water and alcohol is used. As the alcohol used as the liquid dispersion medium, for example, at least one selected from methanol, ethanol, 1-propanol and 2-propanol is preferable. Since water and alcohol easily volatilize easily due to the heat of plasma, they do not interfere with the sublimation reaction and the oxidation reaction of the raw material powder, and since the molecule contains oxygen, the oxidation reaction is easily promoted.

When the dispersion liquid is prepared by dispersing the metal tungsten powder or the tungsten compound powder in the dispersion medium, the metal tungsten powder or the tungsten compound powder is preferably contained in the dispersion liquid in the range of 10 to 95% by mass, and more preferably. It is in the range of 40 to 80 mass %. By dispersing in the dispersion liquid in such a range, the metal tungsten powder and the tungsten compound powder can be uniformly dispersed in the dispersion liquid. If it is uniformly dispersed, the sublimation reaction of the raw material powder is likely to occur uniformly. If the content in the dispersion is less than 10% by mass, the amount of raw material powder is too small to efficiently manufacture the powder. When it exceeds 95% by mass, the amount of the dispersion is small and the viscosity of the raw material powder is increased, so that it easily sticks to the container and the handleability is deteriorated.

The crystal structure of the tungsten oxide fine particles can be easily controlled by applying a method of forming a dispersion liquid of metal tungsten powder or a tungsten compound powder and blowing it into plasma. Specifically, it is easy to obtain at least one kind of tungsten oxide fine particles having a crystal structure in which at least one kind selected from monoclinic crystals and triclinic crystals, or an orthorhombic mixture thereof is mixed. Further, by using the tungsten compound solution as a raw material, the sublimation reaction can be performed uniformly, and the controllability of the crystal structure of the tungsten oxide fine particles is further improved. The method using the dispersion liquid as described above can also be applied to the arc discharge treatment.

When carrying out the sublimation step by irradiating a laser or an electron beam, it is preferable to use metal tungsten or a tungsten compound in a pellet form as a raw material. Since the irradiation spot diameter of a laser or an electron beam is small, it is difficult to supply it by using a metal tungsten powder or a tungsten compound powder, but it can be efficiently sublimated by using a pelletized metal tungsten or a tungsten compound. The laser is not particularly limited as long as it has sufficient energy to sublime metallic tungsten or a tungsten compound, and a CO 2 laser is preferable because it has high energy.

When irradiating the pellets with the laser beam or the electron beam, at least one of the irradiation source of the laser beam or the electron beam or the pellets can be moved, whereby the entire surface of the pellets having a certain size can be effectively sublimated. This makes it easy to obtain a tungsten trioxide powder having a crystal structure in which orthorhombic crystals are mixed with at least one selected from monoclinic crystals and triclinic crystals. The above-mentioned pellets can also be applied to inductively coupled plasma processing and arc discharge processing.

The photocatalyst body of the embodiment can be obtained with good reproducibility by heat-treating the tungsten oxide-based fine particles obtained in the sublimation step described above. In the heat treatment step, the tungsten oxide-based fine particles obtained in the sublimation step are heat-treated at a predetermined temperature and time in an oxidizing atmosphere. The heat treatment step is preferably performed in air or an oxygen-containing gas. The oxygen-containing gas means an inert gas containing oxygen. The heat treatment temperature is preferably in the range of 200 to 800°C, more preferably 340 to 650°C. The heat treatment time is preferably in the range of 10 minutes to 5 hours, more preferably 30 minutes to 2 hours. By setting the temperature and time of the heat treatment step within the above range, the crystallinity of the tungsten oxide-based fine particles, the existing amount of surface defects, and the like are in a state suitable for the photocatalyst.

When the heat treatment temperature is lower than 200° C., there is a possibility that the oxidizing effect for converting the powder that has not become tungsten trioxide in the sublimation step into tungsten trioxide cannot be sufficiently obtained. Furthermore, the crystallinity of the tungsten trioxide obtained in the sublimation process cannot be sufficiently enhanced. When the heat treatment temperature exceeds 800° C., the crystallinity of tungsten oxide is excessively increased, and the surface of the fine particles tends to have almost no surface defects such as oxygen vacancies. In either case, the photocatalytic activity of the tungsten oxide-based fine particles cannot be sufficiently enhanced. Furthermore, the crystallinity and surface condition of the tungsten oxide-based fine particles can be controlled to a state suitable for the photocatalyst with good reproducibility by adjusting the temperature rising rate and the temperature lowering rate during the heat treatment within an appropriate range. In the heat treatment step, it is preferable to put the tungsten oxide powder in a furnace heated to a set temperature, take out the tungsten oxide powder from the furnace after a lapse of a predetermined time, and lower the temperature at room temperature. The rate of temperature increase during heat treatment is preferably in the range of 80 to 800° C./minute, and the rate of temperature decrease is preferably in the range of −800 to −13° C./minute.

(Photocatalyst dispersion, photocatalyst coating, photocatalyst film, and products)
Next, a photocatalyst dispersion liquid and a photocatalyst coating material of the embodiment, a photocatalyst film formed by using them, and a product including the photocatalyst film will be described. The photocatalyst dispersion liquid of the embodiment is obtained by dispersing the photocatalyst body of the embodiment in an aqueous dispersion medium so that the particle concentration is in the range of 0.001 to 50 mass %. If the particle concentration is less than 0.001% by mass, the content of the photocatalyst will be insufficient and the desired performance cannot be obtained. When the particle concentration exceeds 50% by mass, the fine particles of the photocatalyst body exist in a state of being too close to each other when formed into a film, and the surface area for sufficiently exhibiting the photocatalytic performance cannot be obtained. Therefore, not only the sufficient performance cannot be exhibited, but also the photocatalyst is contained more than necessary, resulting in an increase in cost. The concentration of the photocatalyst is more preferably 0.01 to 20% by mass.

In the photocatalyst dispersion liquid of the embodiment, the pH of the dispersion liquid is preferably in the range of 1-9. By setting the pH of the photocatalyst dispersion liquid in the range of 1 to 9, the zeta potential becomes negative, so that the dispersion state of the photocatalyst body can be enhanced. With such a dispersion liquid or a coating material using the dispersion liquid, it is possible to apply it thinly and evenly to a substrate. When the pH of the photocatalyst dispersion liquid is less than 1, the zeta potential approaches zero, and the dispersibility decreases. When the pH of the photocatalyst dispersion liquid is higher than 9, the tungsten oxide is easily dissolved. In order to adjust the pH of the photocatalyst dispersion liquid, an acid such as hydrochloric acid, sulfuric acid, tetramethylammonium hydroxide (TMAH), ammonia or sodium hydroxide, or an aqueous alkali solution may be added, if necessary.

The pH of the photocatalyst dispersion liquid is more preferably in the range of 2.5 to 7.5. As a result, the photocatalytic performance (gas decomposition performance) of the film formed using the dispersion liquid or the paint can be further improved. After applying a photocatalyst dispersion liquid having a pH in the range of 2.5 to 7.5 and drying it, observing the surface state of the particles by FT-IR (Fourier transform infrared absorption spectroscopy), hydroxyl groups are found around 3700 cm ^-1. Absorption of is seen. By using such a film as the photocatalyst film, excellent organic gas decomposition performance can be obtained. When the photocatalyst dispersion liquid whose pH is adjusted to 8 is applied and dried, the absorption of hydroxyl groups is decreased and the gas decomposition performance is likely to be deteriorated. When the pH of the photocatalyst dispersion liquid is adjusted to 1.5, hydroxyl groups are present, but the zeta potential approaches 0, so that the dispersibility is slightly reduced and the gas decomposition performance is also slightly reduced.

The photocatalyst dispersion liquid of the embodiment is obtained by dispersing the photocatalyst body of the embodiment in an aqueous dispersion medium. The photocatalyst to be dispersed in the aqueous dispersion medium is not limited to the single fine particles of tungsten oxide as described above, but may be fine particles such as a mixture or complex of tungsten oxide and another metal element. Tungsten oxide and another metal element may be mixed or mixed in advance in the aqueous dispersion medium to be dispersed, or the mixture or the composite may be formed in the aqueous dispersion medium. The types and forms of metal elements other than tungsten are as described above.

The method of mixing or compounding tungsten oxide and another metal element in a dispersion medium is not particularly limited. A representative composite method is described below. Examples of a method of combining ruthenium include a method of adding an aqueous solution of ruthenium chloride to an aqueous dispersion liquid in which fine particles of tungsten oxide are dispersed. Examples of the method of combining platinum include a method of mixing platinum powder with an aqueous dispersion liquid containing tungsten oxide fine particles. Furthermore, a copper compounding method using an aqueous solution of copper nitrate or copper sulfate or an ethanol solution, an iron compounding method using an iron chloride aqueous solution, a silver compounding method using a silver chloride aqueous solution, a platinum using a chloroplatinic acid aqueous solution. The complex method of palladium and the complex method of palladium using an aqueous solution of palladium chloride are also effective. Further, tungsten oxide and a metal element (oxide) may be combined using an oxide sol such as titanium oxide sol or alumina sol. In addition to these, various composite methods can be applied.

An aqueous dispersion medium is used for the photocatalyst dispersion liquid of the embodiment. Water is a typical example of the aqueous dispersion medium. The water-based dispersion medium may contain alcohol in an amount of less than 50% by mass in addition to water. As the alcohol, for example, methanol, ethanol, 1-propanol, 2-propanol or the like is used. If the content of alcohol exceeds 20% by mass, the photocatalyst may aggregate. Therefore, the content of alcohol is more preferably 20% by mass or less. The content of alcohol is more preferably 10% by mass or less. The photocatalyst body of the embodiment may be dispersed in a water-based dispersion medium such as water or alcohol in a state of being mixed, supported, and impregnated with a material having an adsorption performance such as activated carbon or zeolite. The photocatalyst dispersion liquid may contain the photocatalyst body in such a state.

The photocatalyst dispersion liquid of the embodiment can be used as it is as a film forming material. The photocatalyst dispersion liquid may be mixed with a binder component to prepare a paint, and this paint may be used as a film forming material. The coating material contains an aqueous dispersion and at least one binder component selected from an inorganic binder and an organic binder. The content of the binder component is preferably in the range of 5 to 95% by mass. When the content of the binder component exceeds 95% by mass, the desired photocatalytic performance may not be obtained. When the content of the binder component is less than 5% by mass, a sufficient binding force cannot be obtained and the film properties may be deteriorated. By applying such a coating material, it is possible to adjust the strength, hardness, adhesion to the substrate, etc. of the film to a desired state.

Examples of the inorganic binder include products obtained by decomposing hydrolyzable silicon compounds such as alkyl silicates, silicon halides, and partial hydrolysates thereof, organic polysiloxane compounds and polycondensates thereof, silica, colloidal silica. , Water glass, silicon compounds, phosphates such as zinc phosphate, metal oxides such as zinc oxide and zirconium oxide, heavy phosphates, cement, gypsum, lime, and frit for enamel. As the organic binder, for example, fluorine resin, silicone resin, acrylic resin, epoxy resin, polyester resin, melamine resin, urethane resin, alkyd resin, etc. are used.

By applying the above-mentioned photocatalyst dispersion liquid or photocatalyst coating material to a substrate, a film containing a photocatalyst can be formed stably and uniformly. As the base material for forming the photocatalytic film, glass, ceramics, plastic, resin such as acrylic resin, paper, fiber, metal, wood and the like are used. The film thickness is preferably in the range of 2 to 1000 nm. If the film thickness is less than 2 nm, the state in which the tungsten oxide-based fine particles are allowed to uniformly exist may not be obtained. When the film thickness exceeds 1000 nm, the adhesion of the photocatalyst film to the base material decreases. The film thickness is more preferably in the range of 2 to 400 nm.

The photocatalyst film of the embodiment exhibits photocatalytic performance not only under irradiation with visible light but also under ultraviolet light. In general, visible light is light in the wavelength range of 380 to 830 nm, and includes sunlight, general lighting such as white fluorescent lamps, white LEDs, light bulbs, halogen lamps, xenon lamps, and blue light emitting diodes and blue lasers. It is the light emitted as a light source. Ultraviolet light is light in the wavelength range of 10 to 400 nm and is included in light emitted from the sun, mercury lamps, and the like. The photocatalyst film of the embodiment exhibits not only the photocatalytic performance in a normal indoor environment, but also the photocatalytic performance under the irradiation of ultraviolet light. Photocatalytic performance means that a pair of electrons and holes are excited for one photon by absorbing light, and the excited electrons and holes activate the hydroxyl group or acid on the surface by redox reduction, and The generated active oxygen species have an effect of oxidizing and decomposing organic gas and the like, and further an effect of exerting hydrophilicity, antibacterial/bactericidal performance and the like.

The product of the embodiment has a film formed by using the above-mentioned photocatalyst dispersion liquid or photocatalyst paint. Specifically, a film is formed by applying a photocatalyst dispersion liquid or a photocatalyst paint on the surface of a base material constituting a product. The film formed on the surface of the base material may contain zeolite, activated carbon, porous ceramics, or the like. The photocatalyst film and products equipped with it have excellent decomposition performance for organic gas such as acetaldehyde and formaldehyde under irradiation of visible light, and exhibit high activity even in low illuminance. Further, it has a higher photocatalytic performance even under irradiation with ultraviolet light than the conventional visible light responsive photocatalyst, and can broaden the use environment. The photocatalyst film of the embodiment exhibits hydrophilicity when the contact angle of water is measured. Further, it exhibits a high antibacterial action in the evaluation of antibacterial property against Staphylococcus aureus and Escherichia coli under the irradiation of visible light.

Specific examples of products provided with the photocatalyst film of the embodiment include air conditioners, air purifiers, fans, refrigerators, microwave ovens, dishwashers/dryers, rice cookers, pots, pot lids, IH heaters, washing machines, vacuum cleaners, Lighting fixtures (lamps, fixtures, shades, etc.), hygiene items, toilet bowls, washbasins, mirrors, bathrooms (walls, ceilings, floors, etc.), building materials (indoor walls, ceiling materials, floors, outer walls, etc.), interior items (curtains) , Carpets, tables, chairs, sofas, shelves, beds, bedding, etc.), glass, sashes, handrails, doors, knobs, clothes, filters used for home appliances, etc., stationery, kitchen utensils, used in automobile interior space Examples include members. By providing the photocatalyst film of the embodiment, a photocatalytic effect can be imparted to the product. Examples of the substrate to be applied include glass, ceramics, plastics, resins such as acrylic resin, paper, fibers, metals, and wood.

When fibers are used as the base material, synthetic fibers such as polyester, nylon and acrylic, regenerated fibers such as rayon, natural fibers such as cotton, wool and silk, and mixed fibers, mixed woven materials and mixed spun products thereof are used as the fiber material. To be The fibrous material may be loose-fluffed. The fibers may have any form such as woven fabric, knitted fabric, and non-woven fabric, and may be those that have been subjected to ordinary dyeing and printing. When the photocatalyst dispersion liquid is applied to a fiber material, it is convenient to use the photocatalyst body according to the embodiment together with a resin binder and fix the same to the fiber material.

As the resin binder, water-soluble type, water-dispersible type and solvent-soluble type resins can be used. Specifically, melamine resin, epoxy resin, urethane resin, acrylic resin, fluororesin and the like are used, but not limited to these. When fixing the photocatalyst body to the fiber material using the photocatalyst dispersion liquid of the embodiment, for example, the photocatalyst dispersion liquid is mixed with a water-dispersible or water-soluble resin binder to prepare a resin liquid, and the fiber material is added to the resin liquid. After being impregnated with, it is squeezed with a mangle roll or the like and dried. By increasing the viscosity of the resin liquid, one side of the fiber material can be coated with a known device such as a knife coater. It is also possible to attach the photocatalyst to one side or both sides of the fiber material using a gravure roll.

When the photocatalyst is attached to the fiber surface using the photocatalyst dispersion liquid, if the amount of attachment is too small, the photocatalytic performance such as gas decomposition performance and antibacterial performance of tungsten oxide cannot be sufficiently exhibited. When the adhesion amount is too large, the performance of the tungsten oxide is exhibited, but the texture of the fiber material may be deteriorated. For this reason, it is preferable to select an appropriate adhesion amount according to the material and application. A garment or an interior article using a fiber having a photocatalyst contained in a photocatalyst dispersion liquid attached to the surface thereof can exhibit excellent deodorizing effect and antibacterial effect under irradiation of visible light in an indoor environment. It also exhibits photocatalytic performance even when irradiated with ultraviolet light.

Next, specific examples of the present invention and evaluation results thereof will be described. In the following examples, a method of applying inductively coupled plasma treatment to the sublimation process is used as the powder manufacturing method, but the present invention is not limited to this.

(Example 1, Comparative Example 1)
A tungsten trioxide powder having an average particle diameter of 0.5 μm was prepared as a raw material powder. This raw material powder was sprayed on the RF plasma together with a carrier gas (Ar), and argon was supplied as a reaction gas at a flow rate of 40 L/min and oxygen was supplied at a flow rate of 40 L/min. In this way, the tungsten oxide powder was produced through the sublimation step in which the raw material powder was sublimated and subjected to the oxidation reaction. The tungsten oxide powder that was not heat-treated was used as sample A (comparative example). Samples B to E (Examples) were prepared by heat-treating the above-mentioned tungsten oxide powder in the atmosphere at temperatures of 300°C, 500°C, 575°C, and 600°C. Further, the same tungsten oxide powder was heat-treated in the atmosphere at a temperature of 1000° C. to prepare Sample F (Comparative Example). The heat treatment time was 1 hour each. Further, in producing Samples B to E, the temperature during the heat treatment was rapidly heated to a predetermined temperature, taken out from the furnace after 1 hour, and then lowered at room temperature.

The average primary particle diameter (D50) and BET specific surface area of Samples A to F (tungsten oxide powder) were measured. The average primary particle diameter was measured by image analysis of a TEM photograph. Hitachi's H-7100FA was used for TEM observation, 50 or more particles were extracted by subjecting an enlarged photograph to image analysis, and a volume-based integrated diameter was calculated to calculate a D50 diameter. The BET specific surface area was measured using a specific surface area measuring device Macsorb 1201 (trade name) manufactured by Mountech Co., Ltd. The pretreatment was carried out in nitrogen at 200° C. for 20 minutes. Table 1 shows the measurement results of the average primary particle diameter (D50 diameter) and BET specific surface area of Samples A to F.

Next, Raman spectroscopic analysis of samples A to F (tungsten oxide powder) was performed. The Raman spectrum of each sample was measured under the environment of a temperature of 25° C. and a humidity of 50% using a spectrograph PDP-320 (trade name) manufactured by Photon Design. The measurement conditions are as follows: the measurement mode is micro Raman, the measurement magnification is 100 times, the beam diameter is 1 μm or less, the light source is Ar ⁺ laser with a wavelength of 514.5 nm, the laser power in the tube is 0.5 mW, and the diffraction grating is a single 600 gr/ mm, the cross slit was 100 μm, the slit was 100 μm, and the detector was a CCD of 1340 channels manufactured by Nippon Roper Co. The Raman shift measurement range was 100 to 1500 cm ⁻¹ . The Raman spectra that are the measurement results of Sample A, Sample D, and Sample F are shown in FIG. In the Raman spectrum of each sample, first peak existing in the range of 268～274Cm ^-1, second peak existing in the range of 630～720Cm ^-1, 3 present in the range of 800～810Cm ^-1 Each wave number of the peak was examined. Furthermore, the ratio (X/Y) of the intensity X of the peak existing in the range of 920 cm ⁻¹ or more and 950 cm ⁻¹ or less to the intensity Y of the peak was calculated. The results are shown in Table 1.

Next, the tungsten oxide powders of Samples A to F were dispersed in water so that the particle concentration was 10% by mass, to prepare photocatalyst dispersion liquids. The obtained photocatalyst dispersion was subjected to the characteristic evaluation described below.

(Example 2, Comparative Example 2)
Using the same tungsten oxide powders of Samples A to F as in Example 1 and Comparative Example 1, a photocatalyst dispersion liquid was prepared as follows. First, the tungsten oxide powder was dispersed in water so that the concentration thereof was 10% by mass. Zirconium oxide with respect to the total amount of tungsten oxide and zirconium oxide, a dispersion liquid in which a tungsten oxide powder is dispersed in water, and an aqueous dispersion liquid in which a zirconium oxide powder having an average primary particle diameter (D50) of 70 nm is dispersed in water. Were mixed so that the ratio was 33% by mass. The mixed dispersion was adjusted with hydrochloric acid and ammonia so that the pH of the mixed dispersion was in the range of 6.5 to 5.5. The dispersion treatment was carried out using a bead mill. The particle concentration of the photocatalyst dispersion liquid thus obtained was 10% by mass.

(Example 3, Comparative Example 3)
Using the same tungsten oxide powders of Samples A to F as in Example 1 and Comparative Example 1, a photocatalyst dispersion liquid was prepared as follows. The tungsten oxide powder was dispersed in water so that the concentration thereof was 10% by mass. A dispersion liquid in which tungsten oxide powder was dispersed in water and a ruthenium chloride solution were mixed so that the ratio of ruthenium oxide to the total amount of tungsten oxide and ruthenium oxide was 0.02% by mass. Ammonia was added dropwise to the mixed solution to adjust the pH to 7. Further, an aqueous dispersion liquid in which zirconium oxide powder having an average particle diameter (D50) of 70 nm was dispersed in water was added dropwise to the mixed liquid to adjust the pH to the range of 6.5 to 5.5. Regarding the mixing ratio of tungsten oxide, ruthenium oxide, and zirconium oxide in the dispersion liquid, the ratio of ruthenium oxide is about 0.017 mass% and the ratio of zirconium oxide is about 33 mass% with respect to the total amount thereof. The particle concentration of the obtained photocatalyst dispersion liquid was 13% by mass.

(Example 4, Comparative Example 4)
Using the same tungsten oxide powders of Samples A to F as in Example 1 and Comparative Example 1, a photocatalyst dispersion liquid was prepared as follows. The tungsten oxide powder was dispersed in water so that the concentration thereof was 10% by mass. Platinum particles having an average particle diameter of 2 nm are mixed with a dispersion liquid in which tungsten oxide powder is dispersed in water so that the ratio of platinum to the total amount of tungsten oxide and platinum is 0.02% by mass, and photocatalyst dispersion is performed. A liquid was prepared.

Next, a photocatalyst film was formed on the glass surface using the photocatalyst dispersion liquids produced in Examples 1 to 4 and Comparative Examples 1 to 4. The photocatalytic performance of the photocatalytic film under visible light irradiation was evaluated. The photocatalytic performance was evaluated by measuring the decomposition rate of acetaldehyde gas. Specifically, the gas decomposition rate was measured under the following conditions using the same flow-type apparatus as used in the evaluation performance (decomposition capacity) of removing nitrogen oxides according to JIS-R-1701-1 (2004).

The decomposition test of acetaldehyde gas was performed as follows. The initial concentration of acetaldehyde is 10 ppm, the gas flow rate is 140 mL/min, and the sample amount is 0.2 g. The sample is prepared by coating on a glass plate of 5×10 cm and drying. The pretreatment is irradiation with black light for 12 hours. A white fluorescent lamp (FL20SS.W/18 manufactured by Toshiba Lighting & Technology Co., Ltd.) is used as a light source, and an ultraviolet cut filter (Clarex N-169 manufactured by Nitto Jushi Kogyo Co., Ltd.) is used to cut wavelengths of less than 380 nm. The illuminance is adjusted to 1000 lx. Wait for the gas adsorption to become stable without irradiating with light. Light irradiation is started after stabilization.

The light is irradiated under such conditions and the gas concentration after 15 minutes is measured to obtain the gas decomposition rate. However, if the gas concentration is not stable after 15 minutes, the concentration is continuously measured until it stabilizes. The gas concentration before light irradiation is A, and the gas concentration when it is stable for 15 minutes or more after light irradiation is B. From these gas concentrations A and B, [Equation: (AB)/A×100 ] The value calculated based on the above is defined as the gas decomposition rate (%). A multi-gas monitor 1412 manufactured by INOVA was used as the gas analyzer. Table 2 shows the measurement results of the gas decomposition rate.

As shown in Table 2, it was confirmed that the photocatalyst films formed using the photocatalyst dispersion liquids of Examples 1 to 4 had a high decomposition rate of acetaldehyde and were completely decomposed. This is because the Raman peak intensity ratio (X/Y) is in the range of more than 0 and 0.04 or less, and the crystalline state and surface state of the tungsten oxide fine particles are in a state suitable for a photocatalyst. it is conceivable that. Therefore, the gas decomposition performance of the photocatalyst film can be enhanced even in an environment where the illuminance of visible light is low and the gas concentration is low. Further, the gas decomposition performance of the photocatalytic film is further improved by the zirconium oxide adsorbing the gas.

Next, the photocatalyst dispersion liquids of Examples 1 to 4 and Comparative Examples 1 to 4 are mixed with an acrylic resin-based resin liquid, and the mixed liquid (paint) is impregnated with a plain fabric made of polyester having a basis weight of 150 g/m ² . Thus, a polyester fiber having a visible light responsive photocatalyst attached thereto was produced. A 5×10 cm sample was cut from each fiber, and the photocatalytic performance under irradiation of visible light was evaluated by the same method as described above. As a result, the polyester fibers to which the photocatalysts of Examples 1 to 4 were attached had a higher decomposition rate of acetaldehyde gas than the fibers impregnated with the coating material using the photocatalyst dispersion liquid prepared in Comparative Examples 1 to 4. Was confirmed. Furthermore, ten samples prepared in the same manner were prepared, and the dispersion of the performance was evaluated. The dispersions of the examples had excellent dispersibility, and it was confirmed that the amount of the photocatalyst attached to the fiber was stable. confirmed. It was also confirmed that the polyester fiber maintained a uniform texture.

Since the photocatalyst dispersion liquids of the above-described examples have excellent dispersibility, it is possible to obtain a uniform photocatalyst film. Then, based on the photocatalytic performance of the photocatalytic film, the decomposition performance of organic gas such as acetaldehyde can be stably obtained, and further, problems such as color unevenness are less likely to occur visually. Therefore, it is suitably used for materials used in the interior space of automobiles, factories, shops, schools, public facilities, hospitals, welfare facilities, accommodation facilities, building materials, interior materials, home appliances and the like used in houses and the like. Further, the photocatalysts of Examples exhibit high gas decomposition performance even in an environment where the illuminance of visible light is low, an environment where ultraviolet light is irradiated in addition to visible light, and an environment where the gas concentration is low. By forming a photocatalyst film on an interior material or interior of a room by using a dispersion liquid or a paint containing such a photocatalyst, it becomes possible to obtain excellent deodorizing and deodorizing effects. Such a film or product can be applied to various applications by taking advantage of the characteristics of the photocatalyst of the embodiment.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and the gist of the invention, and are also included in the invention described in the claims and an equivalent range thereof.

Claims (15)

In a method for producing an interior material, which comprises attaching a photocatalyst to a substrate made of at least one selected from glass, ceramics, plastic, resin, paper, fiber, metal, and wood,
A step of dispersing a photocatalyst in an aqueous dispersion medium to obtain a photocatalyst dispersion,
A step of mixing the photocatalyst dispersion liquid and at least one binder component selected from an inorganic binder and an organic binder to obtain a coating material;
Attaching the coating material onto the base material,
The photocatalyst body comprises tungsten oxide-based fine particles containing tungsten oxide in a range of 5% by mass or more and 100% by mass or less,
In the Raman spectrum by Raman spectroscopy of the photocatalyst, the strength X of peaks observed in the range of 920 cm ^-1 or more 950 cm ^-1 or less with respect to the peak intensity Y observed in a range of 800 cm ^-1 or more 810 cm ^-1 or less The method for producing an interior material, wherein the ratio (X/Y) is 0.001 or more and 0.035 or less. The method for producing an interior material according to claim 1, wherein the tungsten oxide-based fine particles contain a metal element other than tungsten in a range of 0.001% by mass or more and 50% by mass or less. The interior material according to claim 2, wherein the metal element is at least one selected from the group consisting of titanium, zirconium, manganese, iron, ruthenium, nickel, palladium, platinum, copper, silver, cerium, and aluminum. Production method. The method for producing an interior material according to claim 3, wherein the content of the metal element is in the range of 0.005% by mass or more and 10% by mass or less. The method for producing an interior material according to claim 1, wherein the tungsten oxide-based fine particles contain a metal oxide excluding tungsten oxide in a range of 0.01% by mass or more and 70% by mass or less. The method for producing an interior material according to claim 5, wherein the metal oxide is at least one selected from the group consisting of zirconium oxide, titanium oxide, and ruthenium oxide. The method for producing an interior material according to claim 1, wherein the tungsten oxide-based fine particles have an average particle diameter (D50) of 1 nm or more and 30 μm or less. The interior according to any one of claims 1 to 7, wherein the photocatalyst dispersion liquid contains the photocatalyst in the water-based dispersion medium in an amount of 0.001% by mass or more and 50% by mass or less. Method of manufacturing wood. The method for producing an interior material according to any one of claims 1 to 8, wherein the aqueous dispersion medium is at least one selected from water and alcohol. The method for producing an interior material according to claim 1, wherein the pH of the photocatalyst dispersion liquid is 1 or more and 9 or less. The interior according to any one of claims 1 to 10, wherein the pH of the photocatalyst dispersion liquid is adjusted with at least one selected from hydrochloric acid, sulfuric acid, tetramethylammonium hydroxide, ammonia, and sodium hydroxide. Method of manufacturing wood. The method for producing an interior material according to any one of claims 1 to 11, wherein at least one selected from activated carbon, zeolite, and porous ceramics is dispersed in the photocatalyst dispersion liquid. The method for producing an interior material according to any one of claims 1 to 12, wherein the photocatalyst body is adhered by applying the coating material onto the base material to form a photocatalyst film. The method for producing an interior material according to claim 13, wherein the thickness of the photocatalyst film is 2 nm or more and 1000 nm or less. The method for producing an interior material according to any one of claims 1 to 12, wherein the photocatalyst body is attached by impregnating the base material with the coating material.

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