JP2011212613A - Antiviral filter for air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter for an air conditioner which has high antiviral property even under irradiation with visible light of low light intensity.SOLUTION: The filter for an air conditioner includes at least one selected from tungsten oxide particles and composite tungsten oxide particles. When a test piece coated with the particles within the range of 0.01 mg/cmor more and 40 mg/cmor less, is inoculated with at least one selected from a low pathogenic avian influenza virus (H9N2), a highly pathogenic avian influenza virus (H5N1), and a swine influenza virus, the test piece is irradiated with visible light for 24 hours, and then the virus titer is evaluated, the inactivation effect R of the particles, represented by [R=logC-logA] (wherein C is a virus titer TCIDafter preserving an unprocessed test piece for 24 hours under visible light irradiation, and A is a virus titer TCIDafter preserving the test piece coated with the particles for 24 hours under visible light irradiation), is 1 or more.

Description

  The present invention relates to a filter for an air conditioner having antiviral properties.

In recent years, infectious diseases caused by various viruses such as new influenza and bacteria such as O157 have been threatened to human life, and countermeasures are urgent worldwide. From such a viewpoint, the demand for antibacterial and antiviral materials is increasing, and antibacterial and antiviral properties are required in all products. At present, application is progressing with respect to antibacterial properties, but no material with sufficient performance has been developed for antiviral properties.

Photocatalyst is a material that has the function of decomposing organic matter by irradiating light and is expected to have antibacterial and antiviral effects. Antibacterial filters mixed with titanium oxide photocatalyst have been put into practical use. Yes. However, since a photocatalyst made of titanium oxide is excited only by ultraviolet rays, sufficient performance cannot be obtained in an indoor environment with little ultraviolet rays. For example, Patent Document 1 describes the antiviral performance of a filter using titanium oxide, but uses ultraviolet light contained in a fluorescent lamp, and the ultraviolet light is cut by practical illuminance or shade. In an indoor space, sufficient performance cannot be exhibited and its performance is insufficient. As countermeasures, visible light responsive photocatalysts such as titanium oxide carrying a platinum compound that exhibits performance even under visible light and titanium oxide doped with nitrogen or sulfur have been developed. However, a visible light responsive photocatalyst based on titanium oxide has a narrow excitation wavelength range and does not provide sufficient performance under low illuminance as in general indoor lighting. Similarly, no practical photocatalyst has been obtained for antiviral properties, so that the application of antiviral filters to air conditioners has not progressed.

The air-conditioning filter having antiviral properties is a product that is used by being mounted inside a machine, and usually a sufficient amount of light irradiation cannot be obtained. The photocatalyst exhibits its performance by light irradiation, but when used for an air conditioner filter, a material that exhibits antiviral performance is more preferable regardless of the amount of light irradiation. In general, it is said that the virus is inactivated by alcohol, but this is a temporary effect when alcohol is applied,
The product itself does not inactivate the virus, and the virus can reattach. There are also differences in effectiveness depending on the type of virus. Although Ag ions are said to be effective in inactivating viruses, there is a problem that the sustainability of the effect is low.

Since tungsten oxide has a narrower band gap than titanium oxide, it has attracted attention as a material capable of obtaining a photocatalytic action with visible light. Regarding the antibacterial action of tungsten oxide, for example, Non-Patent Document 1 describes that the growth of sulfur-oxidizing bacteria is inhibited in an environment of pH 2.5. Furthermore, it is also known that antibacterial properties by photocatalytic action can be obtained by mixing with titanium oxide. However, conventional antiviral materials based on tungsten oxide are not known.

As described above, a conventional antiviral material has not been obtained practically because it is difficult to evaluate its effect. Development of air conditioner filters using antiviral materials that have such effects is expected regardless of the environment, such as the presence or absence of light irradiation.

Japanese Patent Laid-Open No. 10-33921

“Sewage Association Journal Proceedings” 2005 No. 507 Vol. 42

As described above, conventional photocatalysts do not provide materials with effective antiviral performance, and sufficient performance and sustainability, especially in environments where light irradiation is difficult to obtain, such as inside a machine No air-conditioning filter using any antiviral material has been obtained.
An object of the present invention is to provide an air conditioner filter that solves the above problems and has practical antiviral properties even when incorporated in a general machine.

The antiviral air-conditioning filter according to an aspect of the present invention includes an antiviral photocatalytic material having at least one kind of fine particles selected from tungsten oxide fine particles and tungsten oxide composite fine particles,
In the method according to the antibacterial test method / antibacterial effect of the photocatalyst antibacterial processed product under light irradiation of JIS-R1702 (2006),
Choose from low pathogenic avian influenza virus (H9N2), highly pathogenic avian influenza virus (H5N1), and swine influenza virus on the test piece to which the microparticles are attached in the range of 0.01 mg / cm ² or more and 40 mg / cm ² or less. At least one kind of virus inoculated, using a white fluorescent lamp and an ultraviolet cut filter, and evaluating the virus titer after irradiating visible light having a wavelength of only 380 nm or more and illuminance of 6000 lx for 24 hours, (1)
The inactivation effect R represented by is characterized by being 1 or more.
R = logC-logA (1)
(Where C is the virus titer TCID ₅₀ after storing the unprocessed specimen under visible light for 24 hours.
, A shows the virus titer T after the test piece coated with the fine particles was stored under visible light for 24 hours.
CID ₅₀ . )

According to the present invention, since the particle size, crystal structure, and the like of the tungsten oxide-based fine particles are appropriately controlled, the tungsten oxide-based fine particles are used in an environment that is installed inside the machine and is not easily irradiated with light. Thus, an air conditioner filter having antiviral properties can be provided.

Hereinafter, modes for carrying out the present invention will be described. The antiviral air-conditioning filter according to the embodiment of the present invention includes at least one kind of fine particles (hereinafter referred to as tungsten oxide-based fine particles) selected from tungsten oxide fine particles and tungsten oxide composite fine particles. The tungsten oxide-based fine particles are 0.01 to 40 in the test piece.
When the antiviral evaluation test is conducted with the adhesion in the range of mg / cm ² , the inactivation effect R has a characteristic of 1 or more. Furthermore, it is preferable that the tungsten oxide-based fine particles have a characteristic that the inactivation effect R is 2 or more.

The test for evaluating the antiviral performance shall be carried out by a method according to the antibacterial test method / antibacterial effect of the photocatalytic antibacterial processed product under light irradiation of JIS-R-1702 (2006).
Choose from low pathogenic avian influenza virus (H9N2), highly pathogenic avian influenza virus (H5N1), and swine influenza virus on the test piece to which the microparticles are attached in the range of 0.01 mg / cm ² or more and 40 mg / cm ² or less. Inoculating at least one fungus,
Using a white fluorescent lamp and an ultraviolet cut filter, the wavelength is only 380 nm or more, and the illuminance is 60
The virus titer A after irradiating 00 lx visible light for 24 hours and the virus titer C after inoculating a similar test sample on a non-processed specimen and irradiating the same light source for 24 hours were evaluated. Based on the following formula (1) from the values A and C:
R = log C-log A (1)

The virus titer is evaluated by the following method. The sample is inoculated with virus, and after irradiation with light, the virus solution is diluted with physiological saline, collected, and measured. The collected virus was diluted 10-fold and infected with each cultured MDCK cell (canine kidney-derived cell line).
Incubate for 5 days at a CO2 concentration of 5%. After culturing, observe the presence or absence of cell morphological changes (cytopathic effect), and calculate the amount of virus infected with 50% cultured cells.
CID ₅₀ / ml).

Here, generally visible light refers to light in a wavelength region of 380 nm to 830 nm. In order to evaluate the performance under visible light irradiation, the wavelength in the evaluation of this embodiment is 380 n.
Only visible light of m or more is used. Specifically, JIS-Z-9112 is used as a light source.
It is preferable to perform evaluation by irradiating visible light having a wavelength of only 380 nm or more using an ultraviolet cut filter that cuts light having a wavelength of less than 380 nm. As the white fluorescent lamp, for example, FL20SS · W / 18 manufactured by Toshiba Lighting & Technology Corp. or its equivalent is used. As the ultraviolet cut filter, for example, Clarex N-169 (trade name) manufactured by Nitto Jushi Kogyo Co., Ltd. or its equivalent is used.

To evaluate the antiviral properties of tungsten oxide fine particles, first, the fine particles (fine powder) are mixed with a dispersion medium such as water, and dispersion treatment is performed using an ultrasonic disperser, wet jet mill, bead mill, etc. To do. The obtained dispersion is applied to a test piece such as a glass plate by a general method such as dropping, spin coating, dipping, spraying, or the like to prepare a sample. Such samples are inoculated with virus and evaluated for antiviral properties. In the case where the tungsten oxide fine particles have photocatalytic performance, it is preferable to set conditions so that the powder is not excessively strained by the dispersion treatment in order to exhibit the photocatalytic performance in a state where it is applied to the surface of the test piece.

The anti-virus air-conditioning filter is provided with tungsten oxide-based fine particles on the filter base material, and the method of providing the base material with the surface includes fine particles in the coating, kneading and base material forming steps. It is manufactured by a known method such as a method of forming a layer. When evaluating the antiviral performance of such a filter, an evaluation test is performed using a test piece cut out from the filter. As a method for applying the fine particles to the substrate, as in the antiviral evaluation test of the fine particles, there is a method using a dispersion prepared by performing a dispersion treatment on a mixture of a powder, a dispersion medium and a dispersant as required. Can be mentioned. When the uniformity of the film is required, it is preferable to apply a method such as spin coating, dipping or spraying as the coating method.

Since at least one kind of fine particles selected from the tungsten oxide fine particles and the tungsten oxide composite fine particles used in this embodiment has a very high dispersibility, a film exhibiting antiviral performance can be formed. In the case of tungsten oxide particles having a large particle size so far, a film could not be formed on the surface of the substrate, and thus antiviral properties could not be evaluated. Further, an air conditioner filter exhibiting antiviral performance using tungsten oxide particles having a large particle size has not been obtained.

The tungsten oxide-based fine particles used in the anti-virus air-conditioning filter of this embodiment have a characteristic that the inactivation effect R is 1 or more under the condition where 6000 lx visible light is irradiated for 24 hours. That is, the tungsten oxide-based fine particles have a low pathogenic avian influenza virus (H9N2) and a highly pathogenic avian influenza virus (H5N1) when the adhesion amount of the fine particles to the test piece is in the range of 0.01 to 40 mg / cm ^2. ,
It exhibits good antiviral performance against at least one virus selected from swine influenza viruses. The antiviral performance of the tungsten oxide-based fine particles is exhibited in a visible light irradiation environment, and is also exhibited in a daily indoor environment having a relatively low illuminance.

As described above, the tungsten oxide-based fine particles used for the air conditioner filter having antiviral properties exhibit antiviral performance when irradiated with visible light. Accordingly, the anti-virus air-conditioning filter having such tungsten oxide-based fine particles can exhibit practical anti-virus performance even when used in a machine with particularly low illuminance. .

Tungsten oxide fine particles used for air conditioner filters with antiviral properties are
When 6000 lx visible light is irradiated for 24 hours, the inactivation effect R is preferably 1 or more, and more preferably 2 or more. When the irradiation time is 4 hours, the inactivation effect R is preferably 0.5 or more. In addition, when visible light with an illuminance of 1000 lx is irradiated for 24 hours,
The inactivation effect R is more preferably 1 or more. In addition, by using tungsten oxide-based fine particles satisfying such conditions, an air conditioner filter having higher antiviral performance can be realized. Air conditioner filters using such tungsten oxide-based fine particles can exhibit high antiviral performance without being affected by the illuminance of the environment in which they are used.

Further, the air-conditioning filter having antiviral properties according to this embodiment has a small particle size of the tungsten oxide fine particles used and high photocatalytic activity. Therefore, in addition to influenza virus, adenovirus having no envelope, norovirus, envelope It is easy to come into contact with various viruses such as herpes virus and SARS virus, and can be inactivated by degrading the protein of the virus.

The air conditioner filter having antiviral properties as described above can be obtained by controlling the particle size (specific surface area), crystal structure and the like of the tungsten oxide fine particles. The fine particles used in the air conditioner filter having antiviral properties are not limited to the fine particles of tungsten oxide, and may be fine particles of a tungsten oxide composite material. The tungsten oxide composite is a tungsten oxide as a main component containing a transition metal element or another metal element. Transition metal elements are atomic numbers 21-29, 39-47, 57-79, 89-1
09 element. Tungsten oxide composites are Ti, Zr, Mn, Fe, Pd, Pt, C
It is preferable to contain at least one metal element selected from u, Ag, Zn, Al and Ce. At least one metal element selected from Cu, Ag and Zn is effective, and the antiviral performance can be improved in a small amount.

Content of metal elements such as transition metal elements in the tungsten oxide composite is 0.01 to 50
It is preferable to set it as the range of the mass%. If the content of the metal element exceeds 50% by mass, the characteristics as an air conditioner filter having antiviral properties may be deteriorated. The content of the metal element is more preferably 10% by mass or less, and further preferably 2% by mass or less. The lower limit of the content of the metal element is not particularly limited, but the content is preferably 0.01% by mass or more in order to more effectively express the effect of adding the metal element. Cu
The content of at least one metal element selected from Ag, Zn is preferably in the range of 0.01 to 1% by mass in consideration of the effect of the tungsten oxide fine particles and the effect of adding the metal element.

In the tungsten oxide composite material used for the antiviral air conditioner filter, the metal element can be present in various forms. The tungsten oxide composite material can contain a metal element in the form of a simple substance of a metal element, a compound containing a metal element (compound containing an oxide), a composite compound with tungsten oxide, or the like. The metal element contained in the tungsten oxide composite material itself may form a compound with other elements. A typical form of the metal element is an oxide. The metal element is mixed with, for example, a tungsten oxide powder in the form of a simple substance, a compound, a complex compound, or the like. The metal element may be supported on tungsten oxide.

Specific examples of the tungsten oxide composite material include mixed powders containing copper oxide powder in the range of 0.01 to 5% by mass. Metal oxide powders other than copper oxide powder (titanium oxide powder, iron oxide powder, etc.) are also preferably contained in the tungsten oxide composite in the range of 0.01% by mass to 10% by mass. The tungsten oxide composite material may contain a tungsten compound other than the oxide, for example, tungsten carbide. Tungsten carbide is mixed with the tungsten oxide powder in the range of 0.01 mass% or more and 5 mass% or less as the powder.

Tungsten oxide and metal elements (specifically, Ti, Zr, Mn, Fe, Pd, Pt, Cu
, Ag, Zn, Al, and Ce at least one element selected from simple substance, compound, composite compound) are not particularly limited, and mixing method, impregnation method, and supporting method of mixing powders are not limited. It is possible to apply various composite methods such as. A typical composite method is described below. As a method of combining copper with tungsten oxide, a method of mixing tungsten oxide powder and copper oxide powder can be mentioned. After adding and mixing tungsten oxide powder to an aqueous solution of copper nitrate or copper sulfate or an ethanol solution, the mixture is dried at a temperature of 70 to 80 ° C. and then 500 to 55.
A method of firing at a temperature of 0 ° C. is also effective.

Further, for example, it is possible to apply a method (impregnation method) in which tungsten oxide powder is dispersed in an aqueous copper chloride solution or an aqueous copper sulfate solution and this dispersion is dried. The impregnation method is not limited to the copper composite method, but uses an iron composite method using an iron chloride aqueous solution, a silver composite method using a silver chloride aqueous solution, a platinum composite method using a chloroplatinic acid aqueous solution, and a palladium chloride aqueous solution. It can also be applied to the compounding method of palladium. Further, an oxide sol such as a titanium oxide sol or an alumina sol may be used to combine tungsten oxide and a metal element (oxide). In addition to these, various composite methods can be applied.

The tungsten oxide based particles used in the air conditioner filter having antiviral preferably has an average primary particle size in the range of 1~200nm average primary particle diameter (D _50). The tungsten oxide-based fine particles preferably have a BET specific surface area in the range of 4.1 to 820 m ² / g. The average primary particle size is calculated from image analysis of photographs such as SEM and TEM.
= Calculated based on the average primary particle diameter (D ₅₀ ) in the volume-based integrated diameter of 50 or more particles. The average primary particle diameter (D ₅₀ ) may coincide with the average primary particle diameter converted from the specific surface area.

The performance of fine particles having antiviral properties increases as the specific surface area increases and the particle size decreases. When the average primary particle diameter of the tungsten oxide fine particles exceeds 200 nm or the BET specific surface area is less than 4.1 m ² / g, it becomes difficult to form a uniform and stable film, and sufficient antiviral performance is obtained. There is a risk of not. On the other hand, when the average primary particle diameter of the tungsten oxide-based fine particles is less than 1 nm or when the BET specific surface area exceeds 820 m ² / g, the particles become too small and handleability (handleability as a powder) is poor. Antiviral material (
Practicality as fine particles is reduced. The tungsten oxide fine particles have a BET specific surface area of 8.
More preferably, it is in the range of ^{2 to} 410 m ² / g, and the average primary particle size is 2 to 100 nm.
More preferably, it is the range.

The average primary particle diameter of the tungsten oxide type fine particles is preferably in the range of 2.7 to 75 nm, more preferably in the range of 5.5 to 51 nm. BET specific surface area is 11-30
It is preferably in the range of 0 m < ² > / g, more preferably in the range of 16 to 150 m < ² > / g. When the tungsten oxide fine particles are mixed and applied in a dispersion or kneaded into a base material, the dispersibility of the particles decreases if the particle diameter is too small. In order to improve such points, it is preferable to use tungsten oxide-based fine particles having an average primary particle diameter of 5.5 nm or more.

Of the primary particle diameters of tungsten oxide-based fine particles, particles having a size of 40 nm or less are 15
% Or more is preferable. The size of bacteria is about 0.5 to 2 μm, whereas the virus is as small as several tens to 300 nm, which is 1/10 to 1/1 compared to bacteria.
The size is 100. For this reason, in order to inactivate a virus, it is effective that many finer fine particles exist. More preferably, the fine fine particles are uniform, but even if larger particles are contained, the effect can be exhibited by including many fine fine particles. In particular, for viruses having a form having an envelope on the surface, high antiviral performance can be obtained particularly when a large number of fine particles having a small particle diameter are present.

The tungsten oxide constituting the tungsten oxide fine particles and the tungsten oxide composite fine particles is at least one crystal structure selected from monoclinic and triclinic tungsten trioxide,
Alternatively, it preferably has a crystal structure in which orthorhombic crystals are mixed in at least one selected from the monoclinic and triclinic crystals. Tungsten oxide fine particles and tungsten oxide composite fine particles using tungsten oxide having such a crystal structure can stably exhibit excellent antiviral performance. Although it is difficult to identify the abundance ratio of each crystal phase of tungsten trioxide, the crystal structure described above is satisfied when the following conditions (1) and (2) are satisfied when measured by X-ray diffraction method. It can be estimated that it has.

(1) In the X-ray diffraction chart, the first peak (diffraction peak having the highest intensity among all peaks) and the second peak (diffraction peak having the second highest intensity) in the range of 2θ of 22.5 to 25 °
And a third peak (diffraction peak with the third highest intensity).
(2) In the X-ray diffraction chart, a peak where 2θ is in the range of 22.8 to 23.4 ° is A, a peak where 2θ is in the range of 23.4 to 23.8 ° is B, and 2θ is 24. .0-2
4. Intensity ratio (A / D) of peak A to peak D and peak, where C is a peak existing in the range of 4.25 °, and D is a peak in the range of 2θ of 24.25 to 24.5 ° D
Intensity ratio (B / D) of peak B to peak is in the range of 0.5 to 2.0, and intensity ratio of peak C to peak D (C / D) is in the range of 0.04 to 2.5 is there.

The measurement and analysis of X-ray diffraction will be described. X-ray diffraction measurement is performed using a Cu target and Ni filter, and only the smoothing process and background removal are performed so that the analysis is not affected by the difference in processing conditions, and the peak intensity is removed without performing Kα2 removal. Measurement shall be performed. Here, how to read the peak intensity within each 2θ range of the X-ray diffraction chart is:
When the mountain is clear, the peak of the mountain within the range is taken as the peak, and the height is read. When the mountain is not clear but there is a shoulder, the shoulder portion is regarded as a peak within the range, and the height of the shoulder portion is read. When the slope has no peaks or shoulders, the height in the middle of the range is read and regarded as the peak intensity within the range.

When the crystallinity of the tungsten oxide fine particles is low, or when the particle diameter of the tungsten oxide fine particles is very small, 2θ in the X-ray diffraction chart is in the range of 22.5 to 25 °,
(1) It has only one peak and the half width is 1 ° or more.
Or (2) having a first peak and a second peak, and the intensity of the peak valley is 10 of the intensity ratio of the first peak.
% Or more.
Or
(3) It has first, second and third peaks, and the intensity of the lowest valley among the valleys of each peak may be 10% or more of the intensity ratio of the first peak.

In this case, it shows that many finer microparticles | fine-particles exist, and can obtain high antiviral performance.

In addition, the 2θ in the X-ray diffraction chart is in the range of 22.5 to 25 °, the first peak, the second
When the peak m and the third peak are present and the valley of each peak is 10% or more of the intensity ratio with respect to the first peak, it indicates that many finer particles are present, and high antiviral performance Can be obtained.

By using tungsten oxide-based fine particles having the particle diameter (specific surface area) or crystal structure as described above, a material exhibiting antiviral performance can be realized. By applying such an antiviral material to an air conditioner filter, it is possible to obtain an air conditioner filter that exhibits practical antiviral performance even when incorporated in a machine with low illuminance.

Tungsten oxide is known to have a photocatalytic action. The tungsten oxide fine particles used in the antiviral material of this embodiment satisfy the above-mentioned particle size (specific surface area) and crystal structure, and further enhance the crystallinity of tungsten oxide and tungsten oxide composite material, thereby improving the light High antiviral performance is exhibited even under visible light irradiation with a small amount of irradiation. For example, in the peak intensity ratio in the X-ray diffraction chart described above, the intensity ratio (A / D) of peak A to peak D and the intensity ratio (B / D) of peak B to peak D are 0.7 to 2.0, respectively. And the intensity ratio of peak C to peak D (C / D
) Is in the range of 0.5 to 2.5, the photocatalytic activity is increased, and even better antiviral performance can be exhibited.

In the case of a titanium oxide-based photocatalyst, visible light responsiveness can be improved by doping nitrogen or sulfur to enhance visible light absorption performance. Furthermore, by controlling the heat treatment temperature to improve crystallinity or by supporting a metal, recombination of electrons and holes can be prevented and photocatalytic activity can be increased. However, titanium oxide that exhibits high performance under extremely high illuminance also decreases in performance as the illuminance decreases, and no practical photocatalytic performance is obtained at daily low illuminance. Therefore, even if a titanium oxide-based photocatalyst with improved visible light responsiveness is used in an air conditioner filter, practical antiviral performance has not been obtained if it is incorporated in a portion where light does not reach.

By using tungsten oxide-based fine particles satisfying the above-described conditions, it is possible to obtain an air conditioner filter that is incorporated in the machine and has higher antiviral performance in an environment without light irradiation. Here, you may irradiate visible light with respect to the filter for air-conditioners which has antiviral property. At this time, the visible light is not only the light from the white fluorescent lamp described above, but also light from sunlight, a white LED, a general illumination such as a light bulb, a halogen lamp, a xenon lamp, a blue light emitting diode, a blue laser, or the like. May be. Furthermore, the antiviral filter can exhibit higher antiviral performance by irradiating visible light with high illuminance.

The air-conditioning filter having antiviral properties of this embodiment exhibits high performance.
In addition to increasing the specific surface area of tungsten oxide microparticles, reducing the particle size of microparticles, or increasing the amount of finer microparticles to increase the contact area with the virus, thereby increasing the number of active sites. This is because the probability of recombination of electrons and holes decreases due to the improvement of crystallinity.

Tungsten oxide has a band gap of 2.5 to 2.8 eV, and absorbs visible light because it is smaller than titanium oxide. Therefore, excellent visible light responsiveness can be realized. Furthermore, since a typical crystal structure of tungsten oxide is a ReO ₃ structure, a crystal plane having high reaction activity having oxygen in the outermost surface layer is easily exposed. For this reason, high hydrophilicity is exhibited by adsorbing water. Alternatively, by oxidizing the adsorbed water, OH radicals can be generated, whereby molecules and compounds can be oxidized. Therefore, photocatalytic performance superior to anatase and rutile crystals of titanium oxide can be exhibited. In addition, since the tungsten oxide fine particles according to this embodiment have a negative zeta potential in an aqueous solution having a pH of 1 to 7, the tungsten oxide fine particles have excellent dispersibility, and thus can be applied thinly and uniformly to a substrate or the like.

Note that the tungsten oxide-based fine particles (powder) used for the anti-virus air-conditioning filter may contain a metal element as an impurity. The content of the metal element as the impurity element is preferably 2% by mass or less. Examples of the impurity metal element include elements generally contained in tungsten ore and contaminating elements mixed when producing a tungsten compound used as a raw material. For example, Fe, Mo, Mn, Cu, Ti, Al, Ca, N
i, Cr, Mg and the like. This is not the case when these elements are used as constituent elements of the composite material.

The tungsten oxide fine particles (powder) used in the anti-virus air-conditioning filter according to the embodiment of the present invention are preferably produced by the following method, but are not limited thereto. The tungsten oxide fine particles are preferably produced by applying a sublimation process. It is also effective to combine a heat treatment process with a sublimation process. According to the tungsten trioxide-based fine particles produced by such a method, the average primary particle diameter and the BET specific surface area described above,
A crystal structure can be realized stably. Furthermore, the average primary particle diameter approximates to the value converted from the BET specific surface area, and fine particles (fine powder) with small particle size variation can be provided stably.

First, the sublimation process will be described. In the sublimation step, the metal tungsten powder, the tungsten compound powder, or the tungsten compound solution is sublimated in an oxygen atmosphere,
This is a step of obtaining tungsten trioxide fine particles. 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 the metal tungsten powder, the tungsten compound powder, or the tungsten compound solution as a raw material while sublimating, a tungsten oxide powder in a fine particle state 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 a 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 gas phase, and further, the metal tungsten vapor that has become the gas phase is oxidized, Tungsten oxide fine particles are obtained. Even when a solution is used, it becomes a gas phase through tungsten oxide or a compound. Thus, 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 process, impurities are hardly contained in the tungsten oxide fine particles obtained by sublimation in an oxygen atmosphere. 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 and tungsten oxide powder are particularly preferable as a raw material for 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 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.

When producing the tungsten oxide composite fine particles, in addition to the tungsten raw material, a transition metal element and other elements may be mixed in the form of a metal, a compound containing an oxide, a composite compound, or the like. By treating tungsten oxide simultaneously with other elements, composite compound fine particles such as a composite oxide of tungsten oxide and other elements can be obtained. The tungsten oxide composite fine particles can also be obtained by mixing and supporting tungsten oxide fine particles with simple particles or compound particles of other metal elements. There are no particular limitations on the method of combining tungsten oxide and other metal elements, and various known methods can be applied.

Metal tungsten powder and tungsten compound powder as tungsten raw materials are 0.1 to
It is preferable to have an average particle size in the range of 100 μm. The average particle diameter of the tungsten raw material is more preferably in the range of 0.3 μm to 10 μm, still more preferably 0.3 μm to 3 μm.
The range is desirably 0.3 μm to 1.5 μm. If a metal tungsten powder or tungsten compound powder having an average particle diameter within the above range is used, sublimation is likely to occur.

When the average particle diameter of the tungsten raw material is less than 0.1 μm, the raw material powder is too fine,
In addition to the necessity of prior adjustment of the raw material powder and a decrease in handleability, it is expensive and industrially undesirable. If the average particle size of the tungsten raw material exceeds 100 μm, a uniform sublimation reaction is difficult to occur. 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.

In order to improve the antiviral performance, it is preferable that the particle size variation is small and the particle size includes many small particle sizes. In order to obtain such fine particles, it is necessary to appropriately control the processing amount and the energy input amount. is there. Generally, when producing fine and uniform particles, it is better to reduce the amount of processing such as particle generation and heat treatment. However, industrially, it is necessary to consider productivity, and the amount of processing must be increased. In that case, the variation in particle diameter and crystallinity tends to increase. However, by optimizing conditions such as particle generation and heat treatment temperature, time, atmosphere, etc., it is possible to exhibit high photocatalytic activity even if there are many fine particles with high activity and there are variations in particle characteristics. It becomes.

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 at a time in an oxygen atmosphere. 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 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 a metal tungsten powder or a tungsten compound powder is dispersed in a predetermined liquid dispersion medium Etc.

Examples of the carrier gas used when metal tungsten powder or tungsten compound powder is blown into plasma include air, oxygen, an inert gas containing oxygen, and the like. 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 crystal structure of the tungsten trioxide fine particles can be easily controlled by applying a method of blowing metal tungsten powder or tungsten compound powder together with a carrier gas and adjusting the gas flow rate, the pressure in the reaction vessel, and the like. Specifically, at least one selected from monoclinic crystal and triclinic crystal (monoclinic crystal, triclinic crystal, or mixed crystal of monoclinic crystal and triclinic crystal), or orthorhombic crystal mixed therewith. Tungsten trioxide fine particles having a crystal structure are easily obtained. The crystal structure of the tungsten trioxide fine particles is more preferably a mixed crystal of monoclinic crystal and triclinic crystal, or a mixed crystal of monoclinic crystal, triclinic crystal and orthorhombic crystal.

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.

When metal tungsten powder or tungsten compound powder is dispersed in a dispersion medium to prepare a dispersion, the metal tungsten powder or tungsten compound powder is 10 to 95% by mass in the dispersion.
It is preferable to make it contain in 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 crystal structure of the tungsten trioxide fine particles 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. Specifically, tungsten trioxide fine particles having a crystal structure in which at least one selected from monoclinic crystals and triclinic crystals, or mixed orthorhombic crystals are easily obtained. Furthermore, by using a tungsten compound solution as a raw material, the sublimation reaction can be performed uniformly, and the controllability of the crystal structure of the tungsten trioxide fine particles is improved. The method using the dispersion liquid as described above 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 the irradiation spot diameter of a laser or electron beam is small, supply becomes difficult when metal tungsten powder or tungsten compound powder is used, but it can be efficiently sublimated by using pellets of metal tungsten or tungsten compound. 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 a laser beam or an electron beam onto the pellet, the entire 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 and the electron beam or the pellet. This makes it easier to obtain a tungsten trioxide powder having a crystal structure in which orthorhombic crystals are mixed in at least one selected from monoclinic crystals and triclinic crystals. The above pellets can be applied to inductively coupled plasma processing and arc discharge processing.

The tungsten oxide fine particles used in the anti-virus air-conditioning filter of this embodiment can be obtained only by the sublimation process as described above, but the heat treatment process is performed on the tungsten oxide fine particles produced in the sublimation process. It is also effective to do. In the heat treatment step, the tungsten trioxide-based fine particles obtained in the sublimation step are heat-treated at a predetermined temperature and time in an oxidizing atmosphere. Even when the tungsten trioxide fine particles cannot be sufficiently formed by controlling the conditions of the sublimation process, the ratio of the tungsten trioxide fine particles in the tungsten oxide fine particles is 99% or more, substantially 100% by performing the heat treatment. can do. Furthermore, the crystal structure of the tungsten trioxide fine particles can be adjusted to a predetermined structure in the heat treatment step.

Examples of the oxidizing atmosphere used in the heat treatment step include air and oxygen-containing gas. An oxygen-containing gas means an inert gas containing oxygen. Heat treatment temperature is 200-100
It is preferable to set it as the range of 0 degreeC, More preferably, it is 400-700 degreeC. The heat treatment time is preferably 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 ranges, it is easy to form tungsten trioxide from tungsten oxide other than tungsten trioxide. Further, in order to obtain a powder with good crystallinity with few defects, it is preferable to gradually raise or lower the temperature during the heat treatment. Rapid heating or rapid cooling during the heat treatment causes a decrease in crystallinity.

When the heat treatment temperature is less than 200 ° C., there is a possibility that the oxidation effect for converting the powder that has not been changed to tungsten trioxide in the sublimation process into tungsten trioxide cannot be obtained sufficiently. When the heat treatment temperature exceeds 1000 ° C., the tungsten oxide fine particles grow rapidly, so that the specific surface area of the obtained tungsten oxide fine powder tends to decrease. Furthermore, by performing the heat treatment step at the temperature and time as described above, the crystal structure and crystallinity of the tungsten trioxide fine powder can be adjusted.

The anti-virus air-conditioning filter of this embodiment can be applied to filters of various forms and configurations. The anti-virus filter for air conditioner attaches tungsten oxide-based fine particles produced by the manufacturing method as described above to the surface of the filter substrate,
Alternatively, it can be provided by a known method such as kneading into a base material or forming a surface layer containing fine particles in a molding process of equipment. Examples of the method of attaching the tungsten oxide-based fine particles to the surface of the filter substrate include a method in which a dispersion liquid or a paint in which tungsten oxide-based fine particles are dispersed in a dispersion medium such as water or alcohol is applied to the surface of the substrate. . By applying such a method, it is possible to obtain an antiviral air conditioner filter having a surface layer such as a coating film or a coating film having tungsten oxide-based fine particles.

The air-conditioning filter having antiviral properties of this embodiment can be applied to filters of various base materials. Various materials can be applied to the base material, such as non-woven or woven fabrics such as natural fibers, synthetic fibers, and mixed fibers thereof, paper, and foamable resin fabrics.
The natural fiber may be any of plant fibers such as cotton, hemp and pulp, and animal fibers such as hair and silk, but cotton is preferred.
Examples of synthetic fibers include polyamide-based, polyester-based, polyolefin-based, polyacrylonitrile-based, and polyurethane-based fibers. Polyolefin-based and polyester-based fibers are preferable. Of these, polypropylene fiber, polyethylene fiber, polyethylene terephthalate fiber, and polybutylene terephthalate fiber are preferable.
In addition, regeneration of rayon, acetate, etc., semi-synthetic fiber, etc. can be used.
Moreover, the manufacturing method of a nonwoven fabric can be arbitrarily selected, such as a spun pond method, a melt blow method, a point void method, a dry method or a wet method.

It is preferable that the surface layer of the antiviral base material contains 0.1 to 90% by mass of antiviral tungsten oxide fine particles. If the content of the anti-tungsten tungsten oxide fine particles is less than 0.1% by mass, the anti-viral performance may not be sufficiently obtained. When the content of the tungsten oxide fine particles having antiviral properties exceeds 90% by mass, the characteristics of the substrate surface layer may be deteriorated. The thickness of the antiviral surface layer is preferably in the range of 2 to 1000 nm. Layer thickness is 2nm
If it is less than this, the amount of the antiviral property is insufficient, and there is a possibility that sufficient antiviral performance cannot be obtained. When the thickness of the antiviral surface layer exceeds 1000 nm, the antiviral performance can be obtained, but the strength of the surface layer tends to decrease. The thickness of the antiviral surface layer is more preferably in the range of 2 to 400 nm.

The surface layer having antiviral properties may contain an inorganic binder or the like in addition to the antiviral material using tungsten oxide fine particles. Inorganic binders include Si and Ti
An amorphous oxide of at least one element selected from Al, W and Zr. An inorganic binder made of an amorphous oxide is used, for example, by adding it as a colloidal silica, alumina sol, titania sol, zirconia sol or the like into a paint using tungsten oxide fine particles. The content of the inorganic binder is preferably in the range of 5 to 95% by mass. In the surface layer having antiviral properties, if the content of the inorganic binder exceeds 95% by mass, the desired antiviral performance may not be obtained. When the content of the inorganic binder is less than 5% by mass, sufficient bonding strength cannot be obtained.

The form of the filter for air conditioner having antiviral properties of this embodiment is a form in which tungsten oxide fine particles having antiviral properties are attached or impregnated on a base material, and a dispersion containing tungsten oxide fine particles having antiviral properties. And a form in which a paint is applied to a substrate. The anti-viral tungsten oxide fine particles may be used after being mixed, supported, impregnated with a material having adsorption performance such as activated carbon or zeolite. The antiviral filter can be used under irradiation of visible light having an illuminance of 1000 lx or less or in the dark, and has low pathogenic avian influenza virus (H9N2), highly pathogenic avian influenza virus (H5N1), and swine influenza virus It is used for the purpose of antiviral against at least one virus selected from the group consisting of However, anti-viruses other than these viruses can be used for the purpose.

Further, the anti-virus air-conditioning filter of this embodiment has an illuminance of 1000 l.
Because it has antiviral performance even under irradiation with visible light below x, when it is installed and used inside a machine where light does not reach, not only the outer surface layer of the filter but also the inner side of the stacked filter Anti-virus performance can be exhibited even if it is provided in the layer of the filter, and by providing it on the surface of multiple layers, it becomes possible to increase the efficiency of collecting and inactivating the virus of the filter, resulting in higher performance. A filter for an air conditioner can be provided.

Since the air-conditioning filter having antiviral properties of this embodiment exhibits practical antiviral performance, it can obtain antiviral performance even when used in an environment where light inside the machine is difficult to reach. The antiviral performance can be exhibited even at night with little light. Unlike conventional antiviral agents using antiviral metal ions, it is possible to stably exhibit practical antiviral performance without degradation of performance due to alteration.

[Example]
Next, specific examples of the present invention and evaluation results thereof will be described. As a method for producing the powder, ammonium tungstate is used, or inductively coupled plasma treatment is applied to the sublimation process, but the present invention is not limited to this.
The filter was evaluated by dispersing the obtained fine particles in water to prepare an aqueous dispersion,
Using an O ₂ binder, the cotton fiber was attached to a fabric having a basis weight of 90 g / m ² , and a 5 cm × 5 cm test piece was cut out from the cotton fiber fabric to which the fine particles were adhered, and the antiviral property was evaluated in the same manner as the fine particles. did. The unprocessed test piece used here was a cloth on which only the same amount of SiO ₂ binder as the sample was adhered. However, the base material used for the filter and the coating method are not limited thereto.

Example 1
A tungsten oxide pellet having a density of 4.7 g / cm ³ was prepared as a raw material. This was placed in a reaction vessel and irradiated with a CO ₂ laser while maintaining the pressure at 3.5 kPa while flowing oxygen at a flow rate of 10 L / min. The tungsten oxide fine particles produced by the laser treatment were heat-treated in the atmosphere at 900 ° C. for 0.5 h to obtain the fine particles of Example 1.
The average primary particle diameter (D ₅₀ ) and BET specific surface area of the obtained fine particles were measured. The average primary particle size was measured by image analysis of a TEM photograph. H-7100FA made by Hitachi for TEM observation
It was used to extract particles 50 or more toward the image analysis enlarged photographs were calculated D ₅₀ seeking integration diameter on a volume basis. The content ratio was calculated from the cumulative frequency of particles having a size of 40 nm or less. The measurement of the BET specific surface area is a specific surface area measuring device Macsorb12 manufactured by Mountec.
01 was used. Pretreatment was performed in nitrogen at 200 ° C. for 20 minutes. Table 1 shows the measurement results of the average primary particle diameter (D ₅₀ ), the ratio of particles of 40 nm or less, and the BET specific surface area.

Furthermore, X-ray diffraction of the obtained fine particles was performed. X-ray diffraction is Rigaku X-ray diffraction device R
Using INT-2000, a Cu target, a Ni filter, and a graphite (002) monochromator were used. Measurement conditions are tube voltage: 40 kV, tube current: 40 mA.
Divergence slit: 1/2 °, scattering slit: automatic, light receiving slit: 0.15 mm, 2θ measurement range: 20 to 70 °, scanning speed: 0.5 ° / min, sampling width: 0.004 °. In the measurement of the peak intensity, only the smoothing and background removal processes were performed without removing Kα2. The smoothing was performed using Savizky-Golay (least square method), and filter points 11 were set. Background removal was performed with a linear fit and threshold value σ3.0 within the measurement range. Based on the X-ray diffraction results, the number of peaks existing between 22.5 and 25 ° of the fine particles and up to the third peak, and the intensity ratio with respect to the first peak between the valleys of the peaks are shown in Table 1.

Next, the antiviral performance of the obtained fine particles was evaluated. First, after mixing the fine particles with water, ultrasonic dispersion treatment was performed to prepare a dispersion. At this time, colloidal silica having a mass ratio of 0.1 was mixed in order to strengthen the adhesion of the fine particles to the test piece substrate. By spreading this dispersion on a 5 × 5 cm glass plate and drying at 200 ° C. for 30 minutes, 10 m
A sample coated with g of tungsten oxide fine particles was prepared. The amount of fine particles attached is 0.4mg
/ Cm ² . Here, the glass plate which apply | coated only the same amount colloidal silica as a sample was produced as a non-processed test piece.
The antiviral evaluation of the test piece was made in accordance with JIS-R-1702 (2006), “Antimicrobial test method / antimicrobial effect of photocatalytic antibacterial processed product under light irradiation”. However, a white fluorescent lamp (FL20SS · W / 18 manufactured by Toshiba Lighting & Technology Co., Ltd.) is used as the light source, and light having a wavelength of less than 380 nm is emitted using an ultraviolet cut filter (manufactured by Nitto Jushi Kogyo Co., Ltd., Clarex N-169). The illuminance was adjusted to 6000 lx. Moreover, the virus titer (virus infectivity titer) was measured using low pathogenic avian influenza virus (H9N2 subtype) instead of bacteria.

The specific evaluation procedure is as follows. First, 100 μL of influenza virus is inoculated on each test specimen and unprocessed test specimen, and each surface is covered with a film.
It was allowed to stand under conditions of 35 ± 1 ° C. and 90% relative humidity. Next, visible light with an illuminance of 6000 lx was irradiated with a fluorescent lamp, and after a certain reaction time (0 h and 24 h), the virus solution was recovered by diluting with physiological saline. Further, the recovered solution was diluted 10-fold, infected with cultured MDCK cells (canine kidney-derived cell line), and cultured for 5 days at 37 ° C. and 5% CO ₂ concentration. After culturing, the presence or absence of cell morphological change (cytopathic effect) was observed, and the amount of virus infected with 50% cultured cells was calculated to determine the virus titer (TCID ₅₀ / mL) per mL. The virus titer was determined as an average value of three evaluation tests. Further, the inactivation effect R <6000 lx, 24 h> was obtained by subtracting the virus titer of the test piece to which fine particles after 6000 lx irradiation passed 24 h from the virus titer of the unprocessed test piece after elapse of 6000 lx irradiation for 24 h. .
Similarly, from the virus titer after 24 hours of 1000 lx irradiation, the inactivation effect R <100
0 lx, 24 h>, 6000 lx 4 hours after irradiation, inactivation effect R <6
000 lx, 4 h> were determined. The results are shown in Table 1.

There was a decrease of about 1 in the log titer log ₅₀ of the virus titer before the visible light irradiation of the untreated specimen and after 24 hours of 6000 lx irradiation. This is a reduction range equivalent to the case of only a glass plate and no light irradiation, and can be said to be a range of natural reduction.
The tungsten oxide fine particles according to Example 1 had a slightly large particle size, and thus exhibited antiviral properties, but had a small inactivation effect value R. With 4 hours irradiation of 6000 lx, R was 1 or less, and the effect was smaller. These results are thought to be because the tungsten oxide fine particles had a slightly large particle size, so that it was difficult to come into contact with the virus, and it was difficult to decompose proteins due to the photocatalytic effect.
Moreover, when the tungsten oxide microparticles | fine-particles by Example 1 were apply | coated to the cotton fiber cloth by the above-mentioned method and the filter was evaluated, the same result was obtained.

(Example 2)
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 onto RF plasma together with a carrier gas (Ar), and oxygen was allowed to flow as a reaction gas at a flow rate of 80 L / min. At this time, the pressure in the reaction vessel was adjusted to 20 kPa.
In this way, tungsten oxide fine particles were produced through a sublimation process in which the raw material powder was subjected to an oxidation reaction while being sublimated. Average particle diameter (D ₅₀ ) of the obtained tungsten oxide fine particles, 4
The ratio of particles of 0 nm or less and the evaluation of powder properties such as BET specific surface area, the number of peaks existing between 22.5 and 25 ° of the fine particles based on the X-ray diffraction results, and the peak when having up to the third peak The X-ray diffraction evaluation such as the intensity ratio with respect to the first peak of the valley was performed in the same manner as in Example 1. The results are shown in Table 1.
In the same manner as in Example 1, a tungsten oxide fine particle was coated on a glass plate to prepare a test piece. After lapse of 4 hours with 6000 lx visible light irradiation, after 24 hours, with the virus titer after 24 hours with 1000 lx visible light irradiation. The inactivation effect R was evaluated. The results are shown in Table 1. Example 2
The fine particles in each case showed a high inactivation effect.
Moreover, when the tungsten oxide microparticles | fine-particles by Example 2 were apply | coated to the cotton fiber cloth by the above-mentioned method and filter evaluation was implemented, the same result was obtained.

(Examples 3 to 5)
Tungsten oxide fine particles are produced by carrying out a sublimation step in the same manner as in Example 2 except that argon is flowed at a flow rate of 40 L / min as a reaction gas and air is flowed at a flow rate of 40 L / min and the pressure in the reaction vessel is adjusted to 40 kPa. did. However, only in Example 5, the raw material charging speed was set to 1.4 times that in Example 2 and other conditions. Further, the obtained fine particles were obtained in Example 3 at 550 ° C. for 1 h.
In Example 4, heat treatment was performed at 750 ° C. for 1 h, and in Example 5 at 800 ° C. for 0.25 h.
Table 1 shows the powder characteristics and X-ray diffraction evaluation results of the fine particles of Examples 3 to 5 thus obtained. Moreover, about the obtained microparticles | fine-particles, the virus titer was evaluated similarly to Example 1, and the inactivation effect R was calculated | required. The results are shown in Table 1.

Examples 3 to 5 all showed a high inactivation effect, and the smaller the particle size, the higher the effect. In addition, when the average primary particle diameter was almost the same, the inactivation effect was higher when many small particles of 40 nm or less were included. This is probably because the inactivation effect was increased because the particle size was sufficiently small relative to the size of the virus, and the contact area was larger when many smaller particles were included. Example 3 showed high antibacterial performance even though the particle size was larger than that of Example 2 because the crystallinity of the tungsten oxide fine particles was improved and the defects and the like were small, so that the photocatalytic performance such as organic matter decomposition was improved. This is probably because
Moreover, when the tungsten oxide microparticles | fine-particles by Examples 3-5 were apply | coated to the cotton fiber cloth by the above-mentioned method and the filter was evaluated, the same result was obtained.

(Examples 6 to 13)
In Example 6, a sublimation process and a heat treatment process similar to those in Example 3 were performed except that tungsten oxide powder having a large amount of impurities such as Fe and Mo was used as a raw material to be put into plasma, and Fe was changed to 5
Tungsten oxide composite fine particles containing 00 ppm were prepared.
In Example 7, copper oxide (CuO) powder was added to the tungsten oxide fine particles obtained in Example 3 as 0.
. 5% by mass was mixed to produce composite fine particles.
In Example 8, composite fine particles were prepared by mixing the tungsten oxide fine particles obtained in Example 3 with a titanium oxide powder at a ratio of 10% by mass.

Example 9 is the same as Example 3 except that a zirconium oxide powder is mixed with a tungsten oxide powder as a raw material to be introduced into plasma, and then a sublimation process and a heat treatment process are performed to obtain zirconium (Zr). Of tungsten oxide composite material containing 0.2% by mass of was produced.
In Example 10, the tungsten oxide fine particles obtained in Example 3 were dispersed in an aqueous palladium chloride solution. The dispersion was centrifuged, and the supernatant was removed and washed twice by adding water, and the powder after removing the supernatant was dried at 110 ° C. for 12 hours to obtain palladium (P
A tungsten oxide composite fine particle containing 0.5% by mass of d) was produced.

In Example 11, the tungsten oxide fine particles obtained in Example 3 were dispersed in an aqueous manganese chloride solution. The dispersion was centrifuged, and the supernatant was removed and washed with water more than twice. Then, the fine particles after removal of the supernatant were dried at 110 ° C. for 12 hours to obtain 0.05% manganese (Mn). Tungsten oxide composite fine particles containing mass% were prepared.
In Example 12, the tungsten oxide fine particles obtained in Example 3 were dispersed in an aqueous chloroplatinic acid solution, irradiated with visible light and charged with methanol, and supported by a photoprecipitation method. Centrifugation was performed and the supernatant was removed and washed twice with water, and then the supernatant was removed.
Tungsten oxide composite fine particles containing 0.2% by mass of platinum (Pt) were produced by drying at 20 ° C. for 12 hours.

In Example 13, the tungsten oxide fine particles obtained in Example 3 were dispersed in an aqueous silver nitrate solution and supported by photoreduction treatment. After performing centrifugation, removing the supernatant and washing with addition of water twice, by drying the powder after removing the supernatant at 110 ° C. for 12 hours,
Tungsten oxide composite fine particles containing 0.01% by mass of silver (Ag) were produced.
The powder characteristics and X-ray diffraction evaluation results of the fine particles thus obtained are shown in Table 1. Moreover, about the obtained microparticles | fine-particles, the virus titer was evaluated similarly to Example 1, and the inactivation effect R was calculated | required. The results are shown in Table 1.

The composite fine particles obtained in Examples 6 to 13 exhibited an inactivation effect R equivalent to or greater than that of Example 3, and had high antiviral properties.
In Example 14, the tungsten oxide fine particles obtained in Example 3 were dispersed in an alumina sol, and this dispersion was dried at 110 ° C. for 12 hours to obtain ₂ alumina (Al ₂ O ₃ ).
Tungsten oxide composite fine particles containing mass% were prepared.
In Example 15, the tungsten oxide fine particles obtained in Example 3 were dispersed in an aqueous cerium chloride solution. The dispersion was centrifuged, and the supernatant was removed and washed twice by adding water, and the powder after removing the supernatant was dried at 110 ° C. for 12 hours to oxidize 0.1% by mass of Ce. Tungsten composite fine particles were prepared.
Moreover, when the tungsten oxide composite fine particles according to Examples 6 to 13 were applied to a cotton fiber cloth by the above-described method and the filter was evaluated, similar results were obtained.

(Comparative Example 1)
Using commercially available tungsten oxide powder (made by Rare Metallic) as a reagent,
Measurements and evaluations similar to those in Example 1 were performed. The powder characteristics are shown in Table 1. Furthermore, tungsten oxide fine particles were applied on a glass plate in the same manner as in Example 1. However, since the particle size was extremely large, a film could not be formed, and the virus titer could not be evaluated.
Moreover, when it applied to cotton fiber cloth similarly by the above-mentioned method and the filter was evaluated, virus titer was not able to be evaluated similarly.

(Comparative Example 2)
Virus titer was evaluated in the same manner as in Example 1 using nitrogen-doped titanium oxide powder as a visible light responsive photocatalyst. Table 1 shows the powder characteristics and the inactivation effect. Nitrogen-doped titanium oxide powder has an inactivation effect as small as 0.1 when irradiated with visible light having an illuminance of 6000 lx for 24 hours, and almost no antiviral performance was obtained with low illumination and short-time light irradiation.
Further, when this powder was used to evaluate a filter using a cotton fiber cloth by the above-described method, antiviral performance was not obtained.

(Comparative Example 3)
Alcohol and virus generally used for sterilization were simultaneously inoculated on a 5 × 5 cm glass plate, and the virus titer was evaluated. The results are shown in Table 1. The virus inactivation effect was obtained. However, when the glass plate used in the test was used again for evaluation, no inactivation effect was obtained, and naturally, after the alcohol was volatilized, there was no effect.

(Example 16)
Aqueous paint was prepared by mixing and dispersing 5% by mass of tungsten oxide fine particles obtained in Example 3 with 0.5% by mass of amorphous ZrO ₂ and water, and applying the mixture to a cotton fiber cloth. The thickness of the surface layer having tungsten oxide fine particles on the surface of the fiber cloth is about 200 nm. A test piece of 5 × 5 cm was cut out from this cotton fiber cloth, and antiviral properties were evaluated in the same manner as the evaluation of fine particles. The unprocessed test piece used here was an unprocessed cotton fiber cloth.

Table 1 shows the powder characteristics of the fine particles used in Example 16 and the results of X-ray diffraction evaluation. Moreover, when the virus titer was evaluated about the produced fiber cloth, the inactivation effect R was high and it had high antiviral property. The results are shown in Table 1.

(Example 17)
In order to evaluate the sustainability of the antiviral performance, the viral titer of the member of Example 14 was evaluated immediately after film formation and after storage for 6 months in a normal environment. Inactivation effect R <6000 lx, 24 h>
Were 4.5 and 4.4, respectively, and it was confirmed that high antiviral properties were maintained even after 6 months.
Moreover, when the same test was implemented with the sample apply | coated to the cotton fiber cloth, the same result was obtained.

(Comparative Example 4)
An Ag antibacterial agent was applied to a 5 × 5 cm glass plate, and the virus titer was evaluated. The results are shown in Table 1. It showed high antiviral properties. However, Ag antibacterial agents are expensive and may cause metal allergy. Furthermore, after leaving the coated glass plate for 6 months, the virus titer was evaluated. As a result, the inactivation effect was almost lost. It was confirmed that the antimicrobial agent has a short performance duration.
Moreover, when this Ag type antibacterial agent was apply | coated to the cotton fiber cloth and evaluated, the same result was obtained.

(Example 18)
The virus titer was evaluated in the same manner as in Example 3 except that 2.5 mg of the tungsten oxide fine particles obtained in Example 3 were applied to a 5 × 5 cm glass plate to prepare a sample. The adhesion amount of the tungsten oxide fine particles is 0.1 mg / cm ² , and the formed film thickness is about 50 n.
m. As a result, the inactivation effect R when irradiated with visible light having an illuminance of 6000 lx for 24 h was 1.5, and the value decreased due to a decrease in the coating amount, but it was confirmed to have antiviral properties. This is presumably because the tungsten oxide powder has a small particle size and can form a uniform coating layer, so that high antiviral properties can be obtained even with a small amount of powder.
Similar results were obtained when the base material was a cotton fiber cloth.

As described above, antiviral air-conditioning filters using tungsten oxide fine particles or tungsten oxide composite fine particles can exhibit practical antiviral performance for a long period of time, and can be used under visible light with low illuminance. However, it exhibits high antiviral properties.

When zeolite tungsten, activated carbon, porous ceramics, diatomaceous earth, etc. are mixed with tungsten oxide fine particles or tungsten oxide composite fine particles and applied, they can not only reduce viruses, but also reduce the occurrence of fungi and mold. confirmed. Therefore, by applying such an antiviral material, it is possible to provide an air conditioner filter that exhibits practical antiviral performance for a long time.

Furthermore, by producing an aqueous dispersion using tungsten oxide fine particles or tungsten oxide composite fine particles, and attaching them to the filter base material using a binder, it is possible to suppress viruses and fungi without degrading the base material, In addition, it is possible to provide a filter for an air conditioner that is excellent in decomposition performance of organic gas such as acetaldehyde.

The antiviral air-conditioning filter according to the embodiment of the present invention exhibits practical antiviral performance under visible light irradiation. In addition, since it has practical antiviral performance even in a low-light environment, in a configuration in which a plurality of filter base materials are laminated, an intermediate layer that is difficult to reach light is provided with fine particles according to the present invention, so that it is resistant to a plurality of layers. Since the virus performance is exhibited, it is possible to provide a filter for an air conditioner having higher virus collection and inactivation efficiency.

Claims (17)

A filter for an air conditioner having antiviral properties, comprising at least one kind of fine particles selected from tungsten oxide fine particles and tungsten oxide composite fine particles,
In the method according to the antibacterial test method / antibacterial effect of the photocatalyst antibacterial processed product under light irradiation of JIS-R-1702 (2006),
From a low pathogenic avian influenza virus (H9N2), a highly pathogenic avian influenza virus (H5N1), and a swine influenza virus to a test piece to which the microparticles were attached in a range of 0.01 mg / cm ² or more and 40 mg / cm ² or less. When inoculating at least one selected virus and evaluating the virus power value after irradiating visible light having a wavelength of 380 nm or more and illuminance of 6000 lx for 24 hours using a white fluorescent lamp and an ultraviolet cut filter ,
A filter for an air conditioner having antiviral properties, wherein the inactivation effect R represented by the formula (1) is 1 or more.
R = logC-logA (1)
(Where C is the virus titer TCID ₅₀ after storing the unprocessed specimen under visible light for 24 hours.
, A is the virus titer TCID ₅₀ after storing the test piece coated with the fine particles under visible light for 24 hours. ) The air-conditioning filter having antiviral properties according to claim 1,
A filter for an air conditioner having antiviral properties, wherein the inactivation effect R of the fine particles is 2 or more. The filter for an air conditioner having antiviral properties according to claim 1 or 2,
When the illuminance of visible light in the test is 1000 lx, the inactivation effect R of the fine particles is 1
An anti-air-conditioning filter having antiviral properties characterized by the above. The filter for an air conditioner having antiviral properties according to claim 1 or 2,
A filter for an air conditioner having antiviral properties, wherein the inactivation effect R of the fine particles when the visible light irradiation time of the test is 4 hours is 0.5 or more. In the filter for air-conditioners which has antiviral property of any one of Claim 1 thru | or 4,
An air conditioner filter having antiviral properties, wherein the average primary particle diameter (D ₅₀ ) of the fine particles is in the range of 1 nm to 200 nm. The air-conditioning filter having antiviral properties according to any one of claims 1 to 5,
A filter for an air conditioner having antiviral properties, wherein the fine particles have a BET specific surface area of 4.1 m ² / g or more and 820 m ² / g or less. In the filter for air-conditioners which has antiviral property of any one of Claim 1 thru | or 6,
A filter for an air conditioner having antiviral properties, wherein 15% or more of particles having a size of 40 nm or less of the primary particle diameter of the fine particles are contained. In the filter for air-conditioners which has antiviral property of any one of Claim 1 thru | or 7,
When the fine particles are measured by an X-ray diffraction method, (2) has a first peak only in the range of 22.5 ° or more and 25 ° or less, and the half width is 1 ° or more.
Or
(2) It has a first peak and a second peak, and the intensity of the valley between the peaks is 10 of the intensity ratio of the first peak.
% Or more.
Or
(3) It has first, second, and third peaks, and the intensity of the lowest valley among the valleys of each peak is the first.
A filter for an air conditioner having antiviral properties, characterized by being 10% or more of the peak intensity ratio. The air-conditioning filter having antiviral properties according to any one of claims 1 to 8,
The air-conditioning filter having antiviral properties, wherein the fine particles contain a transition metal element in a range of 0.01 mass% to 50 mass%. The air-conditioning filter having antiviral properties according to any one of claims 1 to 9,
The fine particles are Ti, Zr, Mn, Fe, Pd, Pt, Cu, Ag, Zn, Al and C.
A filter for an air conditioner having antiviral properties, comprising at least one metal element selected from e in a range of 0.01% by mass to 50% by mass. In the filter for air-conditioners which has antiviral property of any one of Claim 1 thru | or 10,
The fine particles contain at least one metal element selected from Cu, Ag and Zn in an amount of 0.01
A filter for an air conditioner having antiviral properties, characterized by being contained in a range of mass% to 1 mass%. The filter for an air conditioner having antiviral properties according to any one of claims 9 to 11,
A filter for an air conditioner having antiviral properties, wherein the metal element is contained in the fine particles in at least one form selected from a simple substance, a compound, and a complex compound with tungsten oxide. The air-conditioning filter having antiviral properties according to claim 1,
A filter for an air conditioner having antiviral properties, wherein the surface layer comprising the fine particles contains an inorganic binder in a range of 5 mass% to 95 mass%. The anti-virus air-conditioning filter according to claim 13,
A filter for an air conditioner having antiviral properties, wherein the film thickness of the surface layer comprising the fine particles is in the range of 2 nm to 1000 nm. The air-conditioning filter having antiviral properties according to any one of claims 1 to 14,
A filter for an air conditioner having antiviral properties, wherein the base material is cotton fiber. In the filter for air-conditioners which has antiviral property of any one of Claims 1 thru | or 14,
A filter for an air conditioner having antiviral properties, wherein the base material is a nonwoven fabric of polypropylene fibers. In the filter for air-conditioners which has antiviral property of any one of Claims 1 thru | or 16,
A filter for an air conditioner having antiviral properties, wherein the filter has a structure in which a plurality of fibers are laminated, and the fine particles are provided in the second or more layers from the surface.