JP2009121116A - Ceiling material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceiling material which has imparted thereto a function of decomposing odors and fouling adhering to a front surface without using an ultraviolet irradiation means. <P>SOLUTION: The ceiling material has visible ray responsive photocatalytic powder applied at least to part of a front surface of a substrate. The visible ray responsive photocatalytic powder has a color of tungsten oxide photocatalytic powder, in which a* is -5 or less, b* is -5 or more, and L* is 50 or more when expressed by the L*a*b* colorimetric system. Further by setting a light source, odors and fouling can be decomposed even at night. Preferably the light source is a light emitting diode. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ceiling material, and relates to a ceiling material in which a photocatalyst is applied to the surface of a substrate.

Various materials such as concrete, wood, plastic, rubber, and ceramic are used as building ceiling materials. The ceiling material is soiled due to daily life, or is soiled by rain, wind, etc. mixed with dust from the outside. In order to prevent such contamination, photocatalyst has attracted attention. The photocatalyst becomes a photocatalyst layer by applying a coating material containing photocatalyst powder to the surface of a base material serving as a ceiling material.
In recent years, in Japanese Patent Laid-Open No. 2002-45650 (Patent Document 1), titanium oxide is used as a photocatalyst powder. By using titanium oxide powder, a ceiling material having an antifouling effect that can decompose organic substances such as acetaldehyde and nitrogen oxides has been disclosed.
JP 2002-45650 A

However, since the photocatalyst using the titanium oxide powder has colorability, when it is used for a ceiling material, the ceiling material is colored, so that an appearance defect is likely to occur. In addition, since titanium oxide powder is excited by the wavelength in the ultraviolet region,
Even if it is irradiated with sunlight, the decomposition efficiency is not always good because only the ultraviolet region is used.
On the other hand, the visible light responsive photocatalyst has been developed, but its photocatalytic performance has not yet been satisfactory.

  The present invention has been made paying attention to the above points, and provides a ceiling material provided with a photocatalyst that can use visible light without the problem of coloring even when used for a ceiling material.

The ceiling material of the present invention is a ceiling material in which a coating material comprising a visible light responsive tungsten oxide photocatalyst powder is applied to at least a part of the surface of a base material, and the color of the tungsten oxide powder is represented by an L * a * b * table. When expressed in a color system, a * is −5 or less, b * is −5 or more, and L * is 50 or more.
The visible light responsive tungsten oxide photocatalyst powder preferably has an average particle diameter (D50) by image analysis in the range of 1 to 548 nm. Moreover, it is preferable that a ceiling material is used in the environment where sunlight is irradiated. The substrate is preferably at least one of concrete, ceramic, wood, plastic and rubber.
Further, a light source that emits visible light may be provided. The light source is preferably a light bulb. The light source is preferably a light emitting diode that emits light in a wavelength region of 390 to 830 nm. In addition, the light source is preferably a light emitting diode that emits light in a wavelength region of 430 to 500 nm.

  According to the ceiling material of the present invention, since the colorability of the photocatalyst powder is suppressed, it is possible to make use of the color of the surface of the base material, and thus it is possible to suppress defects in appearance. Moreover, since visible light can be utilized, the photocatalytic effect can be exhibited efficiently. Therefore, a ceiling material excellent in antifouling effect, deodorization and antibacterial properties can be provided.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of a ceiling material. In the figure, 1 is a substrate and 2 is a photocatalyst layer. The photocatalyst layer 2 is applied with a paint comprising tungsten oxide powder. The filling ratio of the tungsten oxide powder in the photocatalyst layer is arbitrary, but a range of 30 to 99% is preferable. Moreover, the photocatalyst layer should just be provided in at least one part of the base-material surface. Preferably, the photocatalyst layer is provided on the entire surface. The filling factor can be obtained by (surface area of photocatalyst powder / measured area) × 100 (%) when the surface of the photocatalyst layer is analyzed by EPMA.

  The substrate 1 can be made of various materials such as concrete, ceramic, wood, plastic and rubber. The thickness and size (vertical and horizontal size) of the substrate 1 are arbitrary. The photocatalyst layer may be provided after the building is manufactured using the ceiling material, or the building may be manufactured after the photocatalyst layer is provided on the surface of the base material in advance.

  FIG. 2 shows an example of a ceiling material provided with a light source. In the figure, 1 is a base material, 2 is a photocatalytic layer, 3 is a light source, 4 is a roof, and 5 is an outer wall portion of the building. Moreover, FIG. 2 is an example which manufactured the building using the ceiling material. The light source may be attached to the outer wall as shown in FIG. 2 to illuminate the photocatalyst layer, or the photocatalyst layer may be irradiated with light by being installed directly on the substrate surface or embedded in the substrate.

  Examples of the light source include a light bulb and a light emitting diode. These preferably emit light in the visible light region. By irradiating visible light with a light source, the photocatalytic effect can be exhibited even at night without sunlight. In addition, a light emitting diode is preferable as a light source because it consumes less power than a light bulb. It is preferable that the light emitting diode has a peak wavelength in a region where the wavelength is 390 to 830 nm, and further the wavelength is 430 to 500 nm. If the wavelength is in the visible light region, there is little effect on the human body.

  Moreover, the number of light sources is arbitrary. It is preferable to provide a light source when it is desired to exert a photocatalytic effect in an environment where it is difficult for sunlight to hit directly or at night. At this time, when the visible light irradiation range is narrow with one light source, it is preferable to increase the number of light sources as necessary. Moreover, when a base material is a transparent material, it is also possible to provide a light source inside a base material.

  The ceiling material of the present invention is obtained by applying a coating material containing visible light responsive tungsten oxide photocatalyst powder to the surface of the base material. At this time, it is preferable that the coating material which comprises visible light responsive type tungsten oxide photocatalyst powder is applied by the thickness of 0.01-5.0 micrometers. The thickness of the paint is the thickness after drying. If the coating thickness is less than 0.01 μm, the amount of the photocatalyst powder is small and there is a possibility that a sufficient photocatalytic effect cannot be obtained. On the other hand, if the thickness exceeds 5.0 μm, the photocatalyst powder that does not come into contact with the outside air increases, and a further photocatalytic effect may not be obtained.

  The visible light responsive tungsten oxide photocatalyst has an a * of −5 or less and a b * of − when the color is expressed in the L * a * b * color system (Elster / Aster / Baster color system). 5 or more and L * has 50 or more colors.

The L * a * b * color system is a method used to represent an object color. It was standardized by the International Commission on Illumination (CIE) in 1976, and two are specified in JIS Z-8729. L * represents lightness, and a * and b * represent hue and saturation. Larger L * indicates brighter. a * and b * indicate the color direction, a * indicates the red direction, -a * indicates the green direction, b * indicates the yellow direction, and -b * indicates the blue direction. Also, saturation (c *) = ((a *) ² + (b *) ² ) ^1/2 .

The tungsten oxide photocatalyst powder of this embodiment has a color where a * is −5 or less, b * is −5 or more, and L * is 50 or more. This indicates that the tungsten oxide photocatalyst powder has a hue from yellow to green and has high saturation and lightness. When it has such optical characteristics, the photocatalytic performance by visible light excitation can be improved. Is possible. The color tone of the tungsten oxide photocatalyst powder is considered to change on the basis of composition variation due to oxygen deficiency or the like, light irradiation, etc., and good photocatalytic performance is obtained when it has the above-described hue, saturation, and brightness.

In the case of having a hue near blue, it is considered that there are many oxygen vacancies, and a tungsten oxide powder having such a hue cannot provide sufficient photocatalytic performance. That is, when a * exceeds -5 or b * is less than -5, sufficient photocatalytic performance cannot be obtained. This is presumably because the composition variation occurs in tungsten oxide (WO ₃ ) based on oxygen deficiency or the like. Similarly, when L * is less than 50, sufficient photocatalytic performance cannot be obtained.

Therefore, when the a * indicating the hue of the tungsten oxide powder is −5 or less, b * is −5 or more, and L * indicating the brightness is 50 or more, it is possible to obtain good photocatalytic performance with good reproducibility. . The tungsten oxide photocatalyst preferably exhibits a color having a * of −8 or less, b * of 3 or more, and L * of 65 or more. In such a case, the photocatalytic performance is further improved. Furthermore, it is more desirable that a * is in the range of −20 to −10, b * is in the range of 5 to 35, and L * is 80 or more.

The visible light responsive tungsten oxide photocatalyst powder preferably has an average particle diameter (D50) in the range of 1 to 548 nm. Here, the average particle size (D50) is determined from the average particle size of n = 50 or more particles from image analysis of photographs such as SEM and TEM.

The performance of the photocatalytic material is higher when the specific surface area is larger and the particle size is smaller. The average particle diameter (D50) is preferably in the range of 1 to 75 nm, and more preferably in the range of 3.3 to 15 nm. In order to improve the photocatalytic performance of the tungsten oxide photocatalyst powder, it is preferable that the average particle size is small. However, if the particle size of the tungsten oxide photocatalyst powder is too small, the dispersibility of the particles is lowered and it becomes difficult to obtain a uniform paint. Attention should be paid to the dispersion method.

According to the visible light responsive tungsten oxide photocatalyst powder according to this embodiment, since the tungsten oxide powder having an appropriate color tone is used, it is possible to improve and stabilize the photocatalytic performance by excitation with visible light. Furthermore, the photocatalytic performance can be further improved by controlling the average particle diameter of the tungsten oxide photocatalyst powder.

  Further, for example, when a transparent material is used as the base material, it is preferable that the ceiling material coated with the coating material containing the tungsten oxide photocatalyst powder has a light transmittance of 5% or more at a wavelength of 550 nm. For example, when the substrate is a transparent material, a photocatalytic effect can be obtained by providing a light source inside the substrate. It is also possible to obtain a photocatalytic effect using visible light irradiated from indoor lighting or the like. The light transmittance at a wavelength of 550 nm is preferably 50% or more.

Therefore, the ceiling material coated with the paint having the visible light responsive tungsten oxide photocatalyst powder is adhered to the ceiling material by the visible light responsive tungsten oxide photocatalyst powder excited by sunlight or visible light irradiated from various light sources. The effects of decomposition and removal can be obtained when the soiled material such as oil and odor come into contact with the photocatalyst surface.

Here, the visible light indicates light having a wavelength range of 390 to 830 nm. Normally used indoor lamps have a visible light wavelength range, so when a titanium oxide photocatalyst excited by ultraviolet rays is used, another lamp for irradiating ultraviolet rays is required. On the other hand, since the photocatalyst of the present invention is a visible light responsive type, a commonly used interior lamp can be used as an excitation source for photocatalyst irradiation.

The tungsten oxide photocatalyst powder of this embodiment exhibits photocatalytic properties with light in the visible light region, but is particularly excellent in photocatalytic performance when irradiated with light of 430 to 500 nm. Examples of excitation sources that emit light having a wavelength of 430 to 500 nm include fluorescent lamps and light emitting diodes. In particular, a blue light emitting diode can emit only light having a wavelength of 430 to 500 nm, has high energy efficiency, and can reduce power consumption. If a blue light-emitting diode is installed in the vicinity of the ceiling material and is turned on at a time when sunlight is not irradiated such as at night, a photocatalytic effect can be obtained at night.

  The visible light responsive tungsten oxide photocatalyst powder of the above-described embodiment is produced, for example, as follows. The tungsten oxide powder as a raw material is manufactured by applying a sublimation process. It is also effective to combine a heat treatment process with a sublimation process. According to the tungsten oxide powder produced by applying a sublimation process or a combination of a sublimation process and a heat treatment process, it is possible to stably provide a photocatalyst material having the above-described color tone and preferable average particle diameter and having a small particle size variation. Can do.

  First, the sublimation process will be described. The sublimation step is a step of obtaining a tungsten oxide powder 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 state change from a solid phase to a gas phase or from a gas phase to a solid phase occurs without going through a liquid phase. By oxidizing metal tungsten powder, tungsten compound powder, or tungsten compound solution as a raw material while sublimating, a fine powder tungsten oxide powder can be obtained.

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

  By performing the sublimation process of the tungsten raw material as described above in an oxygen atmosphere, the metal tungsten powder and the tungsten compound powder are instantaneously changed from the solid phase to the vapor phase, and further oxidized by oxidizing the vaporized metal tungsten vapor. A fine tungsten powder is obtained. Even when a solution is used, it becomes a gas phase through tungsten oxide or a compound. Thus, tungsten oxide fine powder can be obtained by utilizing the oxidation reaction in the gas phase. Furthermore, the color tone of the tungsten oxide fine powder can be controlled.

  As a raw material for the sublimation process, impurities are hardly contained in the tungsten oxide powder obtained by sublimation in an oxygen atmosphere, and therefore at least one selected from metal tungsten powder, tungsten oxide powder, tungsten carbide powder, and ammonium tungstate powder. It is preferred to use seeds. Metal tungsten powder or tungsten oxide powder is particularly preferable as a raw material for the sublimation process because it does not include 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 contained as the constituent components, it is easily sublimated instantaneously when an inductively coupled plasma treatment or the like described later is applied in the sublimation process. Examples of such a tungsten compound include WO ₃ , W ₂₀ O ₅₈ , W ₁₈ O ₄₉ , WO _{2 and the} like. Also effective are solutions or salts of tungstic acid, ammonium paratungstate, and ammonium metatungstate.

  The metal tungsten powder or tungsten compound powder as the tungsten raw material preferably has an average particle size in the range of 0.1 to 100 μm. The average particle size 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 desirably in the range of 0.3 μm to 1.5 μm. If a metal tungsten powder or a tungsten compound powder having an average particle diameter within the above range is used, sublimation is likely to occur.

  When the average particle size of the tungsten raw material is less than 0.1 μm, the raw material powder is too fine, so that it is necessary to adjust the raw material powder in advance, the handling property is lowered, and the cost is increased. It is not preferable. If the average particle size of the tungsten raw material exceeds 100 μm, a uniform sublimation reaction hardly occurs. Even if the average particle size is large, a uniform sublimation reaction can be caused by treatment with a large amount of energy, but this is not industrially preferable.

  Examples of the method for sublimating the tungsten raw material in the oxygen atmosphere in the sublimation process 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 or electron beam processing, a sublimation process is performed by irradiating a laser or electron beam. Lasers and electron beams have a small irradiation spot diameter, so it takes time to process a large amount of raw materials at once, but there is an advantage that it is not necessary to strictly control the stability of the raw material particle size and supply amount. .

  Inductively coupled plasma treatment and arc discharge treatment require adjustment of the plasma and arc discharge generation region, but a large amount of raw material powder can be oxidized in an oxygen atmosphere at a time. In addition, the amount of raw material that can be processed at one time can be controlled. Although the gas burner treatment is relatively inexpensive, it is difficult to treat a large amount of raw material powder or raw material solution. For this reason, the gas burner treatment is inferior in terms of productivity. The gas burner treatment is not particularly limited as long as it has sufficient energy for sublimation. A propane gas burner or an acetylene gas burner is used.

  When inductively coupled plasma treatment is applied to the sublimation process, a method is generally used in which plasma is generated using argon gas or oxygen gas, and metal tungsten powder or tungsten compound powder is supplied into the plasma. As a method for 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 a metal tungsten powder or a tungsten compound powder is dispersed in a predetermined liquid dispersion medium Is mentioned.

  Examples of the carrier gas used when metal tungsten powder or tungsten compound powder is blown into the plasma include air, oxygen, and an inert gas containing oxygen. Of these, air is preferably used because of its low cost. When a reaction gas containing oxygen is introduced in addition to the carrier gas, or when the tungsten compound powder is tungsten trioxide, etc., when oxygen is sufficiently contained in the reaction field, a carrier gas such as argon or helium is not used. An active gas may be used. It is preferable to use oxygen, an inert gas containing oxygen, or the like as the reaction gas. In the case of using an inert gas containing oxygen, it is preferable to set the oxygen amount so that the oxygen amount necessary for the oxidation reaction can be sufficiently supplied.

  The color tone of the tungsten oxide photocatalyst powder can be controlled by applying a method of blowing metal tungsten powder or tungsten compound powder together with the carrier gas and adjusting the gas flow rate, the pressure in the reaction vessel, and the like. Specifically, it is easy to obtain a tungsten oxide photocatalyst powder having a color tone represented by the above-described L * a * b * color system.

  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 an oxygen atom in the molecule. Use of the dispersion facilitates handling of the raw material powder. As the liquid dispersion medium having an oxygen atom in the molecule, for example, a medium containing 20% by volume or more 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 are easily volatilized by the heat of plasma, the sublimation reaction and oxidation reaction of the raw material powder are not disturbed, and the oxygen reaction is easily promoted because the molecule contains oxygen.

  In the case of producing a dispersion by dispersing metallic tungsten powder or tungsten compound powder in a dispersion medium, the metallic tungsten powder or tungsten compound powder is preferably contained in the dispersion in a range of 10 to 95% by mass, more preferably It is the range of 40-80 mass%. By dispersing in the dispersion within such a range, the metal tungsten powder and the tungsten compound powder can be uniformly dispersed in the dispersion. If uniformly dispersed, the sublimation reaction of the raw material powder tends to occur uniformly. If the content in the dispersion is less than 10% by mass, the amount of the raw material powder is too small to produce efficiently. If it exceeds 95% by mass, the amount of the dispersion liquid is small, and the viscosity of the raw material powder increases, so that the container becomes easy to stick to the container, and the handleability is lowered.

  The color tone of the tungsten oxide photocatalyst powder can be easily controlled by applying a method in which metallic tungsten powder or tungsten compound powder is used as a dispersion and blown into the plasma. Furthermore, by using a tungsten compound solution as a raw material, the sublimation reaction can be performed uniformly, and the controllability of the color tone of the tungsten oxide photocatalyst powder is improved. The method using the dispersion can also be applied to arc discharge treatment.

When the sublimation process is performed by irradiating with a laser or an electron beam, it is preferable to use as a raw material a metal tungsten or tungsten compound pelletized. Since laser and electron beams have a small irradiation spot diameter, they can be efficiently sublimated by using metal tungsten powder or tungsten compound powder. The laser is not particularly limited as long as it has sufficient energy to sublimate metallic tungsten or a tungsten compound, but a CO ₂ laser is preferable because of its high energy.

  When irradiating the pellet with a laser or an electron beam, the front surface of the pellet having a certain size can be effectively sublimated by moving at least one of the irradiation source of the laser beam or the electron beam or the pellet. This makes it easier to obtain a tungsten oxide photocatalyst powder having a predetermined color tone. The above pellets can also be applied to inductively coupled plasma processing and arc discharge processing.

  The visible light responsive tungsten oxide photocatalyst of this embodiment can be obtained only by the sublimation process as described above, but it is also effective to perform a heat treatment process on the tungsten oxide powder produced by the sublimation process. In the heat treatment step, the tungsten oxide powder obtained in the sublimation step is heat-treated at a predetermined temperature and time in an oxidizing atmosphere. Even if the color tone and average particle size of the tungsten oxide powder vary due to the condition control of the sublimation process, etc., and the characteristics of the photocatalyst are unstable, the color tone and average particle size variation are reduced by heat treatment, and as a result The photocatalytic properties can be stabilized.

  Examples of the oxidizing atmosphere used in the heat treatment step include air and oxygen-containing gas. The oxygen-containing gas means an inert gas containing oxygen. The heat treatment temperature is preferably in the range of 300 to 1000 ° C, more preferably 500 to 700 ° C. The heat treatment time is preferably 10 minutes to 2 hours, more preferably 30 minutes to 1.5 hours. By setting the temperature and time of the heat treatment step within the above ranges, it is easy to form a tungsten oxide photocatalyst having predetermined characteristics.

  When the heat treatment temperature is less than 300 ° C., variations in the color tone and average particle diameter of the tungsten oxide powder cannot be sufficiently reduced. On the other hand, when the heat treatment temperature exceeds 1000 ° C., the tungsten oxide fine particles grow rapidly, so that the particle size of the obtained tungsten oxide powder becomes large and the photocatalytic performance is lowered. By controlling the heat treatment step with the temperature and time as described above, the color tone of the tungsten oxide photocatalyst powder can be adjusted.

  Next, specific examples of the present invention and evaluation results thereof will be described. In the following embodiments, inductively coupled plasma processing is applied to the sublimation process, but the present invention is not limited to this.

Example 1
A tungsten trioxide powder having an average particle size of 0.5 μm was prepared as a raw material powder. This raw material powder is sprayed onto RF plasma together with a carrier gas (Ar), and a sublimation process is performed in which an oxidizing reaction is performed while sublimating the raw material powder by flowing argon at a flow rate of 80 L / min and oxygen at 5 L / min. Tungsten powder was produced. Furthermore, the obtained tungsten oxide powder was heat-treated under the conditions of 900 ° C. × 1.0 h to produce a tungsten oxide photocatalyst powder.

Each value of the L * a * b * color system of the obtained tungsten oxide photocatalyst powder and an average particle diameter by image analysis of a TEM photograph were measured. L * a * b * was measured using a spectroscopic colorimeter CM-2500d manufactured by Konica Minolta. For TEM observation, H-7100FA manufactured by Hitachi, Ltd. was used, and an enlarged photograph was subjected to image analysis to extract 50 or more particles, and a volume-based integrated diameter was obtained to calculate D50.

  Table 2 shows the color measurement results and average particle size (D50) measurement results using the L * a * b * color system. A coating material comprising this visible light responsive tungsten oxide photocatalyst powder was applied to a resin, and the ability to decompose acetaldehyde was measured and evaluated. The decomposition performance of acetaldehyde gas was performed under the conditions shown below using a flow type apparatus similar to the evaluation of nitrogen oxide removal performance (decomposition ability) of JIS-R-1701-1 (2004). A multi-gas monitor 1412 manufactured by INOVA was used as the gas analyzer.

  In the evaluation of the decomposition performance of acetaldehyde gas, the initial concentration of acetaldehyde gas was 10 ppm, the gas flow rate was 140 mL / min, and it was applied to a 5 × 10 cm concrete plate (thickness 1 cm) at a thickness of 0.5 μm. Pretreatment was performed with black light for 12 hours. A fluorescent lamp (FT-21001N-GL15 manufactured by Toshiba Lighting & Technology Corp.) was used as a light source, and a wavelength of 400 nm or less was cut with an acrylic plate. The illuminance was 6000 lx. First, wait until the gas adsorption disappears and stabilizes without irradiating light. Light irradiation is started after stabilization. Light is irradiated under such conditions, and the gas concentration after 15 minutes is measured to determine the residual gas rate. However, if the gas concentration is not stable after 15 minutes, the concentration is continuously measured until it stabilizes.

(Example 2)
A tungsten trioxide powder having an average particle size of 0.5 μm was prepared as a raw material powder. This raw material powder is sprayed onto RF plasma together with a carrier gas (Ar), and further, argon is flowed as a reaction gas at a flow rate of 80 L / min. Produced. Furthermore, the obtained tungsten oxide powder was heat-treated under the condition of 550 ° C. × 0.5 h to produce a tungsten oxide photocatalyst powder. The obtained tungsten oxide photocatalyst powder was measured and evaluated in the same manner as in Example 1, and the results are shown in Table 2. The paint comprising this tungsten oxide photocatalyst powder was applied to wood (5 cm × 10 cm × thickness 2 mm), and the same evaluation as in Example 1 was performed.

(Example 3)
A tungsten trioxide powder having an average particle size of 0.5 μm was prepared as a raw material powder. This raw material powder is sprayed onto RF plasma together with a carrier gas (Ar), and oxygen is flowed as a reaction gas at a flow rate of 75 L / min. Was made. The obtained tungsten oxide photocatalyst powder was measured and evaluated in the same manner as in Example 1, and the results are shown in Table 2. A paint having this tungsten oxide photocatalyst powder was applied to glass, and the same evaluation as in Example 1 was performed.

(Comparative Example 1)
Except for adjusting the pressure in the reaction vessel to 30 kPa and the reduced pressure side, the same sublimation process as in Example 1 was performed to produce a tungsten oxide photocatalyst powder. In addition, the heat processing after a sublimation process was not implemented. The obtained tungsten oxide photocatalyst was measured and evaluated in the same manner as in Example 1, and the results are shown in Table 2. The paint comprising this tungsten oxide photocatalyst was applied to a concrete plate and evaluated in the same manner as in Example 1.

(Comparative Example 2)
The decomposition performance of acetaldehyde gas was evaluated in the same manner as in Example 1 without applying a photocatalyst to the same concrete plate as in Example 1.

(Comparative Example 3)
Titanium oxide as an ultraviolet excitation photocatalyst was applied to the same concrete plate as in Example 1, and the decomposition performance of acetaldehyde gas was evaluated as in Example 1.

Example 4
Using the sample coated with the coating material containing the tungsten oxide photocatalyst powder obtained in Example 2, the light source was a blue LED, and the same evaluation as in Example 1 was performed.

  Table 2 shows the measurement results in each example and comparative example. According to this result, the tungsten oxide photocatalyst powder coated with the tungsten oxide photocatalyst powder satisfying the present invention with each numerical value of the L * a * b * color system of the tungsten oxide photocatalyst powder has high acetaldehyde gas decomposition performance and high photocatalytic effect. I understand that. Further, the sample irradiated with the blue LED was further effective.

  As described above, the ceiling material according to the present example is obtained by applying a paint having a visible light responsive tungsten oxide photocatalyst to at least a part of the surface of the base material, so that no visible light is newly installed. By turning on, the photocatalyst is excited, and an effect of deodorizing and decomposing the dirt substance can be obtained. In addition, the photocatalytic performance can be improved and stabilized based on the color and particle size of the visible light responsive tungsten oxide photocatalyst powder. In particular, it is effective for ceiling materials because it can solve the problem of coloring.

In this example, concrete and wood were used as the base material, and glass was used as the transparent material, but similar effects were obtained with other base materials such as ceramic, plastic, and rubber.
(Examples 1A to 4A, Comparative Examples 1A to 3A)
Next, the antibacterial properties of the ceiling materials of Examples 1 to 4 and Comparative Examples 1 to 3 were examined. For antibacterial properties, water containing Staphylococcus aureus was applied to each sample (Example, Comparative Example), and the number of bacterial colonies after 48 hours was examined. As the light source, the same light source as in Example 1 was used and irradiated with visible light once every 30 minutes for 1 minute. The results are shown below.

As described above, the ceiling material to which the paint having the visible light responsive type tungsten oxide photocatalyst according to the present embodiment is applied can obtain the effect of sterilization and prevention of contamination. Moreover, when a blue LED is used, a greater effect can be obtained.

It is sectional drawing which shows an example of the ceiling material of this invention. It is sectional drawing which shows an example of the ceiling material which installed the light source of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Photocatalyst layer 3 ... Light source 4 ... Roof 5 ... Outer wall part

Claims (8)

  A ceiling material in which a paint comprising a visible light responsive tungsten oxide photocatalyst powder is applied to at least a part of a substrate surface, and when the color of the tungsten oxide powder is expressed in an L * a * b * color system, A ceiling material having a color where a * is -5 or less, b * is -5 or more, and L * is 50 or more.   The ceiling material according to claim 1, wherein the visible light responsive tungsten oxide photocatalyst powder has an average particle diameter (D50) by image analysis in the range of 1 to 548 nm.   The ceiling material according to claim 1 or 2, wherein the ceiling material is used for an indoor ceiling.   The ceiling material according to any one of claims 1 to 3, wherein the base material is at least one of concrete, ceramic, wood, plastic, and rubber.   The ceiling material according to any one of claims 1 to 4, further comprising a light source that emits visible light.   6. The ceiling material according to claim 5, wherein the light source is a light bulb.   6. The ceiling material according to claim 5, wherein the light source is a light emitting diode that emits light in a wavelength range of 390 to 830 nm.   The ceiling material according to claim 7, wherein the light source is a light emitting diode that emits light in a wavelength region of 430 to 500 nm.

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