Porous body and air filter

Abstract

A porous body according to the present disclosure is provided with a skeleton having a three-dimensional network structure. The copper content of the skeleton is 99.9 mass% or more. A plurality of monovalent copper compound nanoparticles are supported on the outer surface of the skeleton. The porosity of the porous body is 90% or more.

Description

Porous materials and air filters

[0001] This disclosure relates to a porous body and an air filter. This application claims priority to Japanese Application No. 2024-146135, filed on August 28, 2024, and incorporates by reference all of the contents of said Japanese application.

[0002] Porous bodies having a skeleton with a three-dimensional network structure are used in antibacterial air filters (Patent Documents 1 to 3).

[0003] JP 9-155124 JP 11-290626 JP 2018-47399

[0004] The porous body of the present disclosure comprises a skeleton having a three-dimensional network structure. The copper content of the skeleton is 99.9% by mass or more. A plurality of monovalent copper compound nanoparticles are supported on the outer surface of the skeleton. The porosity of the porous body is 90% or more.

[0005] Fig. 1 is a schematic cross-sectional view of a porous body of the present disclosure. Fig. 2 is an enlarged view of region R1 in Fig. 1. Fig. 3 is a schematic cross-sectional view of an air filter of the present disclosure. Fig. 4 is a schematic view of aggregated particles composed of monovalent copper compound nanoparticles of the present disclosure.

[0006] When a porous body having a skeleton with a three-dimensional network structure is used in an air filter, the porous body is required to have excellent antibacterial and antiviral properties to prevent people from contracting various infectious diseases. Conventional porous bodies often have insufficient antibacterial and / or antiviral properties.

[0007] According to the present disclosure, it is possible to provide a porous body having excellent antibacterial and antiviral properties, and an air filter including this porous body.

[0008] An embodiment of the present disclosure will be described. [1] The porous body of the present disclosure comprises a skeleton having a three-dimensional network structure. The copper content of the skeleton is 99.9 mass% or more. A plurality of monovalent copper compound nanoparticles are supported on the outer surface of the skeleton. The porosity of the porous body is 90% or more.

[0009] According to the present disclosure, it is possible to provide a porous body having excellent antibacterial and antiviral properties.

[0010] [2] In the above [1], the amount of the monovalent copper compound nanoparticles supported is 0.05 mg / cm ２ 0.5mg / cm or more ２ This makes it possible to provide a porous body having better antibacterial and antiviral properties.

[0011] [3] In the above [1] or [2], at least two of the monovalent copper compound nanoparticles may constitute one or more aggregated particles. The maximum particle size of the aggregated particles may be less than 2.0 μm. This allows for the provision of a porous body having superior antibacterial and antiviral properties.

[0012] [4] In any one of [1] to [3] above, at least two of the monovalent copper compound nanoparticles may constitute one or more aggregated particles. The average particle size of the aggregated particles may be 0.1 μm or more and 1.0 μm or less. This allows for the provision of a porous body having superior antibacterial and antiviral properties.

[0013] [5] In any one of the above [1] to [4], the specific surface area of ​​the porous body is 2000 m ２ / m ３ Over 6000m ２ / m ３ This makes it possible to provide a porous body having better antibacterial and antiviral properties.

[0014] [6] In any one of the above [1] to [5], the skeleton may include a skeleton body and a hollow region surrounded by the skeleton body, and the thickness of the skeleton body may be 0.5 μm or more and 100 μm or less. This makes it possible to provide a porous body having superior antibacterial and antiviral properties.

[0015] [7] An air filter according to the present disclosure includes the porous body according to any one of [1] to [6] above, and a HEPA (High Efficiency Particulate Air) filter located on at least one main surface of the porous body. The porous body is sheet-shaped.

[0016] According to the present disclosure, it is possible to provide an air filter including a porous body having excellent antibacterial and antiviral properties.

[0017] [Details of the embodiments of the present disclosure] Specific examples of the porous body and air filter of the present disclosure will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference numerals represent the same or corresponding parts. In the drawings, the ratio of the length of one part to the length of another part has been changed as necessary for clarity and simplification of the drawings. "Length" may also refer to thickness. This ratio does not necessarily match the actual ratio.

[0018] In the present disclosure, when a compound is represented by a chemical formula and the atomic ratio is not particularly limited, the compound includes compounds with any known atomic ratio, and is not limited to compounds with atomic ratios in the stoichiometric range.

[0019] [Embodiment 1: Porous Body] The porous body of the present disclosure will be described with reference to Figures 1 and 2. The porous body 10 of the present disclosure includes a skeleton 11 having a three-dimensional network structure. The copper content of the skeleton 11 is 99.9 mass% or more. A plurality of monovalent copper compound nanoparticles 40 are supported on the outer surface 21 of the skeleton 11. The porosity of the porous body 10 is 90% or more.

[0020] According to the present disclosure, it is possible to provide a porous body 10 having excellent antibacterial and antiviral properties, and an air filter including the porous body 10. The reason for this is presumed to be as follows.

[0021] (a) The copper content of the skeleton 11 is 99.9 mass % or more. Copper has excellent antibacterial and antiviral properties, and therefore the antibacterial and antiviral properties can be improved.

[0022] (b) A plurality of monovalent copper compound nanoparticles 40 are supported on the outer surface 21 of the skeleton 11. Since the monovalent copper compound nanoparticles 40 have excellent antibacterial and antiviral properties, the antibacterial and antiviral properties can be improved.

[0023] (c) The porosity of the porous body 10 is 90% or more. This allows the outer surface 21 to easily come into contact with air, thereby improving antibacterial and antiviral properties.

[0024] <<Skeleton>> <Shape of Skeleton> The porous body 10 of the present disclosure includes a skeleton 11 having a three-dimensional network structure. In the present disclosure, the "three-dimensional network structure" refers to a three-dimensional network structure. As shown in FIG. 2 , the three-dimensional network structure may have pores 14.

[0025] The skeleton 11 may include a skeleton body 15 and a hollow region 13 surrounded by the skeleton body 15. The skeleton 11 has an inner surface 22 and an outer surface 21. If the skeleton 11 includes the skeleton body 15 and the hollow region 13, the porous body 10 can be made extremely lightweight. The skeleton 11 may be cylindrical.

[0026] There are no particular limitations on the shape of the cross section perpendicular to the longitudinal axis of the cylindrical skeleton 11. The cross section may be, for example, a polygon such as a triangle, a rectangle, or a hexagon, or a circle. Assuming that the skeleton 11 is composed of support sections and node sections connecting the support sections, the longitudinal axis of the skeleton 11 is a straight line connecting a node section and a node section adjacent to the node section.

[0027] Whether or not the skeleton 11 has the skeleton main body 15 and the hollow region 13 can be determined by the following method. The porous body 10 is cut at 10 locations. Each cross section is observed using an electron microscope at a magnification of 3000 times to obtain an observation image. Each observation image is visually observed to determine whether or not the skeleton 11 has the skeleton main body 15 and the hollow region 13.

[0028] When the skeleton 11 includes a skeleton body 15 and a hollow region 13, the thickness of the skeleton body 15 may be 0.5 μm or more and 100 μm or less. This makes it easier to apply a larger amount of antiviral material to the outer surface 21 of the skeleton 11, allowing the porous body 10 to have better antibacterial and antiviral properties. The thickness of the skeleton body 15 may be 0.6 μm or more and 90 μm or less, or 0.7 μm or more and 80 μm or less. The "thickness of the skeleton body 15" refers to the average (arithmetic mean) of the shortest distance from the inner surface 22 of the skeleton 11 to the outer surface 21 of the skeleton 11. The inner surface 22 is the interface between the skeleton body 15 and the internal hollow region 13. The thickness of the skeleton body 15 can be adjusted by adjusting the current density during copper electroplating in the method for producing the porous body 10 described in embodiment 2.

[0029] The thickness of the skeleton body 15 can be measured by the following method. The skeleton body 15 is cut perpendicular to its longitudinal axis. The cross section is observed using an electron microscope at 3000x magnification to obtain an observation image. In the observation image, the thickness is measured at 10 points on the skeleton body 15 using, for example, a ruler. The average (arithmetic mean) of the 10 measured values ​​is calculated. This average is the thickness of the skeleton body 15 of the present disclosure.

[0030] As long as the thickness of the skeleton body 15 of the same porous body 10 is measured by the above method, there will be no significant variation in the measurement results even if the measurement area is changed.

[0031] <Composition of Skeleton> The copper content of the skeleton 11 is 99.9% by mass or more, which can improve the antibacterial and antiviral properties of the porous body 10. The upper limit of the copper content of the skeleton 11 may be 100% by mass.

[0032] The skeleton 11 may consist only of copper. The skeleton 11 may also contain other components, such as aluminum (Al), iron (Fe), silicon (Si), and tin (Sn), as long as the effects of the present disclosure are not impaired.

[0033] The composition of the skeleton 11 can be measured by the following method. A cross section perpendicular to the longitudinal axis of the skeleton 11 is observed using an electron microscope to obtain an observation image. The composition of the skeleton 11 is analyzed using an EDX (Energy Dispersive X-ray spectrometry) device attached to a scanning electron microscope (SEM). The SEM is, for example, a "SUPRA35VP" (trade name) manufactured by Carl Zeiss Microscopy Co., Ltd. The EDX device is, for example, an "Octane Super" (trade name) manufactured by Ametec Co., Ltd.

[0034] As long as the composition of the skeleton 11 of the same porous body 10 is measured by the above method, there will be no significant variation in the measurement results even if the measurement area is changed.

[0035] <Monovalent Copper Compound Nanoparticles> A plurality of monovalent copper compound nanoparticles 40 are supported on the outer surface 21 of the skeleton 11. This can improve the antibacterial and antiviral properties of the porous body 10. The type of monovalent copper compound is not particularly limited. Examples of monovalent copper compounds include copper(I) chloride (CuCl), copper(I) acetate (Cu(CH ３ Copper(I) iodide (CuI), copper(I) bromide (CuBr), copper(I) oxide (Cu ２ O), copper(I) sulfide (Cu ２ The "monovalent copper compound nanoparticles" refer to "particles of a monovalent copper compound" having a size on the order of nanometers. The phrase "monovalent copper compound nanoparticles 40 are supported on the outer surface 21 of the skeleton 11" means that the amount of monovalent copper compound nanoparticles 40 supported on the outer surface 21 of the skeleton 11 is 0 mg / cm. ２ This can be rephrased as "super."

[0036] The amount of monovalent copper compound nanoparticles 40 supported is 0.05 mg / cm ２ 0.5mg / cm or more ２This makes it easy to reduce at least one of the maximum particle size and the average particle size of aggregated particles 41 (described later) on outer surface 21 of skeleton 11, and allows porous body 10 to have better antibacterial and antiviral properties. ２ 0.4mg / cm or more ２ or less, 0.07 mg / cm ２ 0.3mg / cm or more ２ or less, 0.08 mg / cm ２ 0.2mg / cm or more ２ It may be the following:

[0037] The amount of monovalent copper compound nanoparticles 40 supported can be determined by subtracting the mass of the porous body 10 before supporting the monovalent copper compound nanoparticles 40 from the mass of the porous body 10. The mass of the porous body 10 and the mass of the porous body before supporting the monovalent copper compound nanoparticles 40 can be measured using an analytical electronic balance. The analytical electronic balance is, for example, "H-GR-60" (trademark) manufactured by A&D.

[0038] As long as the amount of monovalent copper compound nanoparticles 40 supported in the same porous body 10 is measured by the above method, there will be no significant variation in the measurement results even if the measurement area is changed.

[0039] At least two monovalent copper compound nanoparticles 40 may constitute an aggregated particle 41. FIG. 4 shows an example of an aggregated particle 41. All monovalent copper compound nanoparticles 40 may constitute one or more aggregated particles 41. Only some of the monovalent copper compound nanoparticles 40 may constitute one or more aggregated particles 41. For example, only half of the monovalent copper compound nanoparticles 40 may constitute one or more aggregated particles 41. The maximum particle size of the aggregated particles 41 may be less than 2.0 μm. This makes it easier for the monovalent copper compound nanoparticles 40 to be uniformly dispersed, allowing the porous body 10 to have a higher specific surface area. Therefore, the porous body 10 can have better antibacterial and antiviral properties. The maximum particle size of the aggregated particles 41 may be 0.5 μm or more and less than 2.0 μm, 0.9 μm or more and 1.4 μm or less, or 1.1 μm or more and 1.4 μm or less.

[0040] The maximum particle size of agglomerated particles 41 can be measured by the following method. An arbitrary 40 μm × 50 μm rectangular portion of outer surface 21 is observed using an electron microscope at 3000x magnification to obtain an observation image. Using software "WinRoof" (trademark) manufactured by Mitsutani Corporation, the maximum particle size (circle-equivalent diameter) of agglomerated particles 41 in the observation image is determined. This maximum value is the maximum particle size of agglomerated particles 41.

[0041] As long as the maximum particle size of agglomerated particles 41 in the same porous body 10 is measured by the above method, there will be no significant variation in the measurement results even if the measurement area is changed.

[0042] At least two monovalent copper compound nanoparticles may constitute one or more aggregated particles, and the average particle size of aggregated particles 41 may be 0.1 μm or more and 1.0 μm or less. This makes it easier for the multiple monovalent copper compound nanoparticles 40 to be uniformly dispersed, allowing porous body 10 to have a higher specific surface area. As a result, porous body 10 can have better antibacterial and antiviral properties. The average particle size of aggregated particles 41 may be 0.2 μm or more and 0.9 μm or less, 0.3 μm or more and 0.8 μm or less, or 0.4 μm or more and 0.7 μm or less.

[0043] The average particle size of agglomerated particles 41 can be measured by the following method. Ten randomly selected 40 μm × 50 μm rectangular portions of outer surface 21 are observed using an electron microscope at 3000x magnification to obtain observation images. Using "WinRoof" (trademark) software manufactured by Mitsutani Corporation, the particle sizes (circle-equivalent diameters) of 30 randomly selected agglomerated particles 41 in each observation image are measured. The average (arithmetic mean) of the particle sizes (circle-equivalent diameters) of a total of 300 agglomerated particles is calculated. This average is the average particle size of agglomerated particles 41.

[0044] As long as the average particle size of agglomerated particles 41 in the same porous body 10 is measured by the above method, there will be no significant variation in the measurement results even if the measurement area is changed.

[0045] <<Thickness of Porous Body>> The porous body 10 may be in a sheet form. When the porous body 10 is in a sheet form, the thickness of the porous body 10 may be 0.1 mm or more and 10 mm or less. This allows the porous body 10 to have a larger contact area with air, and the porous body 10 can have better antibacterial properties and better antiviral properties.

[0046] Using a commercially available digital thickness gauge, the thickness of ten arbitrary locations on the sheet-like porous body 10 is measured, and the average (arithmetic mean) of the ten thicknesses is calculated. This average is the thickness of the porous body 10. The digital thickness gauge is, for example, a digital thickness gauge manufactured by Teclock Corporation.

[0047] As long as the thickness of the same sheet-like porous body 10 is measured by the above method, there will be no significant variation in the measurement results even if the measurement area is changed.

[0048] <Porosity of Porous Body> The porosity of the porous body 10 is 90% or more. This can improve the antibacterial and antiviral properties of the porous body 10. The porosity of the porous body 10 may be 90% or more and 100% or less, 91% or more and 99% or less, or 92% or more and 98% or less. The porosity of the porous body 10 is defined by the following formula: Porosity [%] = [1 - (M1 / V1) / d1] x 100, where M1 is the mass [g] of the porous body 10 and V1 is the apparent volume [cm] of the porous body 10. ３ ] M1 / V1: bulk density [g / cm ３ d1: true density of the metal constituting the porous body 10 [g / cm ３ ]

[0049] The porosity of the porous body 10 can be measured, for example, by the following method. A sample having a rectangular size of 100 mm x 100 mm in plan view is cut out from the sheet-like porous body 10. The thickness of this sample is measured using a commercially available digital thickness gauge in the same manner as above. The mass of the sample is measured using a commercially available precision balance, such as the above-mentioned analytical electronic balance. The bulk density is calculated by dividing the mass of the sample by the apparent volume of the sample. The apparent volume of the sample is the product of 100 mm, 100 mm, and the thickness of the porous body 10. The true density of the sample is measured using an "AccuPyc 1330" (trademark) manufactured by Shimadzu Corporation. The true density of the sample corresponds to the true density of the metal constituting the porous body 10. The porosity is calculated by subtracting the value obtained by dividing the bulk density by the true density from 1.

[0050] As long as the porosity of the same porous body 10 is measured by the above method, there will be no significant variation in the measurement results even if the measurement area is changed.

[0051] <Specific surface area of ​​porous body> The specific surface area of ​​the porous body 10 is 2000 m ２ / m ３ Over 6000m ２ / m ３ This allows the porous body 10 to have a larger contact area with air. This allows the porous body 10 to have better antibacterial and antiviral properties. The specific surface area of ​​the porous body 10 may be 2500 m or less. ２ / m ３ Over 5500m ２ / m ３ It may be less than 3000m ２ / m ３ More than 5000m ２ / m ３ It may be less than 3500m ２ / m ３ Over 4500m ２ / m ３The specific surface area of ​​the porous body 10 can be adjusted by adjusting the number of cells in the resin molded body in the step of preparing a porous body precursor in the method for producing the porous body 10 described in embodiment 2. In the present disclosure, the specific surface area of ​​the porous body 10 refers to the area of ​​the outer surface 21 per unit volume of the porous body 10.

[0052] The specific surface area of ​​the porous body 10 is measured using a specific surface area and pore size distribution measuring device. The specific surface area and pore size distribution measuring device is, for example, "BELSORP mini" (trademark) manufactured by MicrotracBEL Corp. As a pretreatment, the porous body 10 is dried using a vacuum dryer. The drying conditions are 120°C for 12 hours or more. The adsorption gas during measurement is nitrogen gas, and the adsorption temperature is 77K.

[0053] As long as the specific surface area of ​​the same porous body 10 is measured by the above method, there will be no significant variation in the measurement results even if the measurement area is changed.

[0054] [Embodiment 2: Method for producing a porous body] A method for producing a porous body according to the present disclosure is described below. The method for producing a porous body according to embodiment 2 includes, in this order, a step of preparing a porous body precursor and a step of obtaining a porous body. In the step of obtaining a porous body, a plurality of monovalent copper compound nanoparticles are supported on the porous body precursor.

[0055] <Step of Preparing a Porous Body Precursor> A sheet of resin molded body (average thickness: 0.1 mm or more and 10 mm or less) having a three-dimensional network structure is prepared. The average thickness can be measured using the same method as for measuring the thickness of a porous body. The resin molded body is, for example, a polyurethane resin molded body or a melamine resin molded body. The cell count of the resin molded body may be 8 cells / inch or more and 60 cells / inch or less. In the present disclosure, the "cell count of the resin molded body" refers to the number of cells per inch of the resin molded body, and the unit of cell count is "cells / inch." The cell count of the resin molded body can be measured as follows: The surface of the resin molded body is observed at 20x magnification using a microscope to obtain a photographed image. The microscope is, for example, a "VHX-8000" (trademark) microscope manufactured by Keyence Corporation equipped with a "VHX-E20" (trademark) lens. Ten straight lines, each 12.7 mm long (i.e., 0.5 inches), are drawn at any location on the photographed image, and the number of cells intersected by each line is counted. The average (arithmetic mean) of the number of cells crossed is calculated, and this average is multiplied by 2 to obtain the number of cells in the resin molded body. A carbon paint is applied to the resin molded body to impart electrical conductivity, thereby obtaining a conductive resin molded body. The outer surface of the conductive resin molded body is electroplated with copper. The outer surface of the conductive resin molded body can be electroplated using a known method. For example, electroplating may be performed using the following bath composition and electrolysis conditions. (Bath composition) Salt (aqueous solution): copper sulfate pentahydrate (plating bath contains 40 g / L to 100 g / L of copper) Sulfuric acid: 100 g / L to 300 g / L (Electrolysis conditions) Temperature: 20°C to 40°C Current density: 1.0 A / dm ２ 5.0A / dm or more ２ Anode: Oxygen-free copper ball with a diameter of 11 mm Time: 12.4 minutes to 62.1 minutes

[0056] Finally, the resin is removed from the electroplated conductive resin molded body by, for example, heat treatment, thereby obtaining a porous body precursor having a skeleton with a three-dimensional network structure.

[0057] <Step of Supporting Monovalent Copper Compound Nanoparticles> The method for producing a porous body of embodiment 2 includes a step of supporting monovalent copper compound nanoparticles on a porous body precursor, thereby allowing the porous body to support a plurality of monovalent copper compound nanoparticles on the outer surface of the skeleton.

[0058] The process of supporting monovalent copper compound nanoparticles is carried out as follows: A monovalent copper compound nanoparticle aqueous solution is prepared. In the monovalent copper compound nanoparticle aqueous solution, the solids concentration of the monovalent copper compound nanoparticles is, for example, 0.5% by mass or more. In the monovalent copper compound nanoparticle aqueous solution, the solids concentration of the monovalent copper compound nanoparticles may be 1.3% by mass or less, 2% by mass or less, or 6% by mass or less. The monovalent copper compound nanoparticle aqueous solution is applied to the outer surface of the skeleton of the porous body precursor by a dipping method. The monovalent copper compound nanoparticle aqueous solution is blown off using an air spray with a wide flat nozzle, thereby adjusting the amount of the monovalent copper compound nanoparticle aqueous solution applied to the outer surface of the porous body precursor. The number of air sprays is, for example, one to four times. The porous body precursor coated with the monovalent copper compound nanoparticle aqueous solution is heated to obtain a porous body. For example, the heating temperature is 50°C to 90°C, and the heating time is 0.5 to 25 hours. As a result, the amount of monovalent copper compound nanoparticles supported, the maximum particle size of the monovalent copper compound nanoparticles, and the average particle size of the monovalent copper compound nanoparticles can be adjusted within desired ranges in the porous body.

[0059] [Embodiment 3: Air Filter] An example of an air filter according to the present disclosure will be described with reference to FIG.

[0060] <Porous Body> The air filter 30 includes a porous body 10. The porous body 10 is in a sheet shape. This makes it possible to provide an air filter 30 including the porous body 10 that has excellent antibacterial and antiviral properties.

[0061] <HEPA Filter> The air filter 30 includes a HEPA filter 20 located on at least one main surface of the porous body 10. This can improve the antibacterial and antiviral properties of the air filter 30. In the present disclosure, a HEPA filter is defined as "an air filter having a particle collection efficiency of 99.97% or more for particles with a particle size of 0.3 μm at a rated air flow rate and an initial pressure loss of 245 Pa or less," as specified in JIS Z 8122.

[0062] <Composition of HEPA filter> The HEPA filter 20 may consist essentially of glass fiber. "Consist essentially of glass fiber" means that the glass fiber content is 99.9% by mass or more. This can improve the particle capture rate of the air filter for fine particles. The upper limit of the glass fiber content of the HEPA filter 20 may be 100% by mass.

[0063] The HEPA filter 20 may be made solely of glass fiber. The HEPA filter 20 may also contain components other than glass fiber, as long as the effects of the present disclosure are not impaired. The components other than glass fiber may be, for example, a nonwoven fabric made from fiber or a nonwoven fabric made by combining multiple fibers. The fiber may be, for example, chemical fiber, cotton, or cellulose pulp. The chemical fiber may be, for example, fluororesin, polypropylene, polyethylene terephthalate (PET), rayon, vinylon, polyester, or acrylic.

[0064] The diameter of the glass fiber may be 1.0 μm or more, which can improve the particle collection efficiency of the air filter for fine particles. The upper limit of the diameter of the glass fiber is not particularly limited, but is, for example, 10 μm.

[0065] The HEPA filter 20 may be a filter paper.

[0066] <Thickness of HEPA Filter> The HEPA filter 20 may be in a sheet form. The thickness of the sheet-shaped HEPA filter 20 may be 10 mm or more and 50 mm or less. This can improve the particle collection efficiency of the air filter for fine particles.

[0067] The thickness of the HEPA filter 20 can be measured in the same manner as the method for measuring the thickness of the porous body 10 .

[0068] As long as the thickness of the same HEPA filter 20 is measured by the above method, there will be no significant variation in the measurement results even if the measurement area is changed.

[0069] <Porosity of HEPA filter> The porosity of the HEPA filter 20 may be 50% or more. This can further improve the antibacterial and antiviral properties of the air filter 30. The lower limit of the porosity of the HEPA filter 20 may be 70%, 80%, or 90%. The upper limit of the porosity of the HEPA filter 20 is not particularly limited, but may be 100%, 99%, or 98%. The porosity of the HEPA filter 20 is defined by the following formula: Porosity [%] = [1 - (M2 / V2) / d2] x 100, where M2 is the mass [g] of the HEPA filter 20 and V2 is the apparent volume [cm ３ ] M2 / V2: Bulk density [g / cm ３ d2: True density of the metal constituting the HEPA filter 20 [g / cm ３ ]

[0070] The porosity of the HEPA filter 20 can be measured by the same method as that for measuring the porosity of the porous body 10 .

[0071] As long as the porosity of the same HEPA filter 20 is measured by the above method, there will be no significant variation in the measurement results even if the measurement area is changed.

[0072] [Embodiment 4: Method for manufacturing an air filter] The air filter according to embodiment 4 can be manufactured by the same method as the conventionally known method, except that the porous body according to embodiment 1 is used.

[0073] The present disclosure will be specifically described below based on examples, but the present invention is not limited to the following examples.

[0074] Example 1 <<Preparation of Porous Body>> In Example 1, porous bodies of Samples 1 to 5 and Sample 101 were prepared as follows.

[0075] <Step of Preparing Porous Body Precursor> A polyurethane resin molded body sheet was prepared. The polyurethane resin was a foamed resin, and the number of cells in the molded body sheet was 47 cells / inch. The average thickness of the molded body sheet was the same as the thickness of the porous body listed in Table 2. A carbon paint was applied to the resin molded body to impart electrical conductivity, thereby obtaining a conductive resin molded body. Next, electroplating was performed on the outer surface of the conductive resin molded body using the following bath composition and electrolysis conditions. (Bath composition) Salt (aqueous solution): copper sulfate pentahydrate (plating bath containing 70 g / L of copper) Sulfuric acid: 200 g / L (Electrolysis conditions) Temperature: 30°C Current density: 1.9 A / dm ２ Anode: Oxygen-free copper ball with a diameter of 11 mm Time: 32.7 minutes The electroplated conductive resin molded body was heated at 1000°C for 60 minutes to remove the resin, thereby obtaining a porous body precursor having a skeleton with a three-dimensional network structure.

[0076] <Step of Supporting Monovalent Copper Compound Nanoparticles> A monovalent copper compound nanoparticle aqueous solution was prepared for producing the porous bodies of Samples 1 to 5. In this aqueous solution, the solids concentration of the monovalent copper compound nanoparticles is as shown in Table 1. Commercially available Cufitec (registered trademark) particles were used as the monovalent copper compound nanoparticles. The monovalent copper compound nanoparticle aqueous solution was applied to the outer surface of the skeleton of the porous body precursor by dipping. Using an air spray with a wide flat nozzle, the monovalent copper compound nanoparticle aqueous solution was blown off under the conditions shown in Table 1, thereby adjusting the amount of monovalent copper compound nanoparticle aqueous solution applied to the outer surface of the porous body precursor. Using a thermostatic bath, the porous body precursor to which the monovalent copper compound nanoparticle aqueous solution had been applied was heated under the conditions shown in Table 1. In all of the columns in the "Step of Supporting Monovalent Copper Compound Nanoparticles" in Table 1, "-" indicates that the step of supporting monovalent copper compound nanoparticles was not performed.

[0077]

[0078]

[0079]

[0080] <<Characteristic Evaluation of Porous Body>> <Copper Content> The copper content of each sample porous body was determined by the method described in Embodiment 1. The results are shown in the "Content [mass %]" column of the "Copper" column in Table 2.

[0081] <Supported Amount of Monovalent Copper Compound Nanoparticles> The supported amount of monovalent copper compound nanoparticles for each sample porous body was determined by the method described in Embodiment 1. The results are shown in the "Supported Amount [mg / cm 3]" column of "Monovalent Copper Compound Nanoparticles" in Table 2. ２ ]" column.

[0082] <Maximum particle size of aggregated particles> For each sample porous body, the maximum particle size of aggregated particles was determined by the method described in Embodiment 1. The results are shown in the "Maximum particle size [μm]" column under "Aggregated particles" in Table 2.

[0083] <Average particle size of aggregated particles> For each sample porous body, the average particle size of aggregated particles was determined by the method described in embodiment 1. The results are shown in the "Average particle size [μm]" column under "Aggregated particles" in Table 2.

[0084] <Porosity of Porous Body> The porosity of each sample porous body was determined by the method described in Embodiment 1. The results are shown in the "Porosity [%]" column of Table 2.

[0085] <Specific surface area of ​​porous body> The specific surface area of ​​each sample porous body was determined by the method described in embodiment 1. The results are shown in Table 2 under "Specific surface area [m ２ / m ３ ]" column.

[0086] <Presence or Absence of Hollow Region> For each sample porous body, whether or not the skeleton comprises a skeleton main body and a hollow region surrounded by the skeleton main body was determined by the method described in embodiment 1. The results are shown in the "Presence or Absence of Hollow Region" column in Table 2. The entry "Present" in the "Presence or Absence of Hollow Region" column in Table 2 means that it was determined that "the skeleton comprises a skeleton main body and a hollow region surrounded by the skeleton main body."

[0087] <Thickness of Skeleton Body> The thickness of the skeleton body of each sample porous body was determined by the method described in Embodiment 1. The results are shown in Table 2 in the column "Thickness of Skeleton Body [μm]".

[0088] <Thickness of Porous Body> The thickness of the porous body of each sample was determined by the method described in Embodiment 1. The results are shown in Table 2 in the column "Thickness of Porous Body [mm]".

[0089] <Antiviral Evaluation Test> According to "JIS L 1922," a method for evaluating the antiviral properties of textile products, an antiviral evaluation test was conducted on the porous body of each sample to measure the infectivity titer of the inoculated virus. The virus species inoculated was influenza A virus (H3N2, A / Hong Kong / 8 / 68), and the host cells were MDCK cells (a canine kidney-derived cell line). The specific measurement method is as follows. The porous body of each sample was sterilized in an autoclave, dried, and cut into a test piece measuring 2 cm x 2 cm. The test piece weighed 0.4 g ± 0.05 g. The test piece was placed in a vial, and 200 μL of a virus solution adjusted to 4.5 × 10 PFU / mL was dropped into it. The vial containing the test piece was left to stand at 25 °C for 0.5 hours. 20 mL of washout solution was added to the vial, and washing was performed by repeating 5 cycles of 5-second stirring. The viral infectivity in the washout solution was measured by the plaque method. The results are shown in the "Infectivity Titer [Log PUF]" column in the "Antiviral Evaluation Test" column in Table 3. An infectivity titer of 4 Log PUF or less means excellent antiviral properties.

[0090] <Antibacterial Evaluation Test> According to "JIS L 1902," a method for evaluating the antibacterial properties of textile products, an antibacterial evaluation test was conducted on the porous body of each sample, and the viable cell count of the inoculum was measured. The inoculum was Escherichia coli (Escherichia coli. BRC3972). The specific measurement method is as follows. The porous body of each sample was cut into a test piece measuring 2 cm x 2 cm. The test piece weighed 0.4 g ± 0.05 g. The test piece was placed in a vial, and 200 μL of bacterial solution was dropped onto it. The vial containing the test piece was left to stand at 37°C for 18 hours. 20 mL of washout solution was added to the vial, and washout was performed by repeatedly stirring for 5 seconds five times. The viable cell count in the washout solution was measured by counting the number of colonies on an agar medium. The results are shown in the "Viable cell count [LogPUF / sample]" column of the "Antibacterial property evaluation test" column in Table 3. A viable cell count of 1.3 LogPUF / sample or less means excellent antibacterial property.

[0091] The porous bodies of Samples 1 to 5 are examples. The porous body of Sample 101 is a comparative example. The antibacterial and antiviral properties of the porous bodies of Samples 1 to 5 were superior to those of the porous body of Sample 101. Therefore, the porous bodies of Samples 1 to 5 have excellent antibacterial and antiviral properties.

[0092] In the porous body of sample 5, the amount of monovalent copper compound nanoparticles supported was 0.5 mg / cm ２ The maximum particle size of the aggregated particles was larger than 2.0 μm, and the average particle size of the aggregated particles was larger than 1.0 μm. Therefore, the infectivity titer and viable cell count of the porous body of Sample 5 were larger than those of the porous bodies of Samples 1 to 4. In other words, the antibacterial and antiviral properties of the porous bodies of Samples 1 to 4 were superior to those of the porous body of Sample 5.

[0093] The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope thereof.

[0094] REFERENCE SIGNS LIST 10 Porous body 11 Skeleton 13 Hollow region 14 Hole portion 15 Skeleton main body 20 HEPA filter 21 Outer surface 22 Inner surface 30 Air filter 40 Monovalent copper compound nanoparticles 41 Aggregated particles

Claims

1. A porous body having a skeleton with a three-dimensional network structure, wherein the copper content of the skeleton is 99.9% by mass or more, a plurality of monovalent copper compound nanoparticles are supported on the outer surface of the skeleton, and the porous body has a porosity of 90% or more.

2. The amount of the monovalent copper compound nanoparticles supported is 0.05 mg / cm ２ 0.5mg / cm or more ２ The porous body according to claim 1, wherein:

3. The porous body according to claim 1 or 2, wherein at least two of the monovalent copper compound nanoparticles constitute one or more aggregated particles, and the maximum particle size of the aggregated particles is less than 2.0 μm.

4. The porous body according to claim 1 or 2, wherein at least two of the monovalent copper compound nanoparticles constitute one or more aggregated particles, and the average particle size of the aggregated particles is 0.1 μm or more and 1.0 μm or less.

5. The specific surface area of ​​the porous body is 2000 m ２ / m ３ Over 6000m ２ / m ３ The porous body according to any one of claims 1 to 4, wherein:

6. A porous body according to any one of claims 1 to 5, wherein the skeleton comprises a skeleton body and a hollow region surrounded by the skeleton body, and the thickness of the skeleton body is 0.5 μm or more and 100 μm or less.

7. An air filter comprising the porous body according to any one of claims 1 to 6 and a HEPA filter located on at least one main surface of the porous body, wherein the porous body is in the form of a sheet.

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