Filtration member for antiviral air filter

Abstract

A filtration member for an antiviral air filter, having an upstream fiber layer for which the contact angle with respect to water is 60° or less, and a downstream fiber layer for which the contact angle with respect to water is 90° or greater, wherein the filtration member has an antiviral agent and a dispersant either on the upstream fiber layer or on the upstream-fiber-layer-side surface of the downstream fiber layer, and the solid fraction mass ratio of the antiviral agent and the dispersant ((mass of solid fraction of antiviral agent) / (mass of solid fraction of dispersant)) is 0.20-5.0.　The present invention provides a filtration member for an antiviral air filter in which the dust collection performance of the filter is ensured, and the amount of antiviral agent adhering to the filter is reduced and a high virus inactivation rate is achieved irrespective of changes in the environment around the filter.

Description

Antiviral air filter media

[0001] The present invention relates to a filter medium for antiviral air filters that is suitably used for air filters.

[0002] Conventionally, air filters have been used to purify air by removing pollen, dust, etc. from the air. Air filters used in air purifiers and the like use filter materials made of glass fiber, paper, or nonwoven fabric, and the filter materials are pleated to increase the filtration area and filtration performance. Furthermore, low-rigidity materials such as meltblown nonwoven fabrics have poor pleat retention, so they are usually pleated by bonding rigid nonwoven fabrics together for reinforcement.

[0003] In recent years, consumer needs have led to demand for air filters to be equipped with a variety of functions beyond just removing pollen and dust. For example, it is said that the globalization of humanity is increasing the risk of viral infection outbreaks, resulting in large-scale human damage. Furthermore, not only is the scope of infection expanding, but new types of viruses, such as avian influenza, MERS coronavirus, Ebola virus, and norovirus, are emerging, resulting in fatalities, and solutions and countermeasures are strongly required.

[0004] However, because viruses infect cells through various media and are much smaller than bacteria (tens to hundreds of nanometers), they require different measures than bacteria that replicate on their own. Furthermore, enveloped viruses, such as influenza viruses, are highly contagious and can even be transmitted through droplets from infected people. Previous countermeasures have included wearing masks and equipping air filters to combat airborne infections, and using protective gear such as gloves and gowns to combat contact infections, but these measures are not effective enough. In particular, there is a strong demand these days for measures to combat viral infections in textile products that surround humans, in order to prevent infection at the border.

[0005] In addition, there is a growing need for air filters that not only provide protection against viral infections but also have multiple functions such as antibacterial, antifungal, and antiallergenic properties.

[0006] Patent Document 1 discloses a dust collection filter to which tea extract components with antibacterial and antiviral properties have been added. Conventional dust collection filter units can kill mold and bacteria, but do not inactivate viruses that cause many diseases. Therefore, there is a demand for a filter that can inactivate viruses in addition to killing mold and bacteria. However, this document imparts deliquescent properties to the entire filter material, which makes it easy for bacteria and viruses to enter the filter from the upstream side of the airflow. However, since there is no material to block the flow of bacteria and viruses, the bacteria and viruses escape to the downstream side, causing the viruses to spread again.

[0007] Patent Document 2 discloses a harmful substance removal material carrying an antibody that removes harmful substances in a gaseous atmosphere by adjusting the humidity level around the antibody to a level at which the antibody is active. While this document describes the antibody as a method for inactivating viruses, antibodies are easily altered by environmental changes and are therefore unsuitable for use in air filters such as automobile cabin filters, which may be subject to high temperatures and humidity. Furthermore, because the virus inactivation rate varies depending on humidity, the material is only effective when used during periods of low humidity when infections such as influenza viruses are more prevalent.

[0008] Japanese Patent Application Laid-Open No. 10-315 Japanese Patent Application Laid-Open No. 2004-313755

[0009] Therefore, the present invention provides a filter medium for antiviral air filters that ensures the dust collection performance of the filter and achieves a high virus inactivation rate even when the amount of antiviral agent attached is reduced, regardless of changes in the environment surrounding the filter.

[0010] The filter material for antiviral air filters has an upstream fiber layer having a contact angle with water of 60° or less and a downstream fiber layer having a contact angle with water of 90° or more, wherein the filter material has an antiviral agent and a dispersion aid on the surface of the upstream fiber layer or the downstream fiber layer facing the upstream fiber layer, and the solids mass ratio of the antiviral agent to the dispersion aid (solids mass of the antiviral agent / solids mass of the dispersion aid) is 0.20 to 5.0.

[0011] The antiviral air filter medium of the present invention preferably satisfies any one of the following (1) to (11). (1) The basis weight of the solid content mass of the antiviral agent is 0.01 to 4.0% of the basis weight of the upstream fiber layer or the downstream fiber layer containing the antiviral agent. (2) The downstream fiber layer is an electret nonwoven fabric. (3) The antiviral agent contains a compound having a metal atom. (4) The antiviral agent contains an organic compound having ionic properties. (5) The antiviral agent contains a naturally occurring component or a derivative thereof. (6) The antiviral agent further has antibacterial, antifungal, or antiallergenic properties. (7) The dispersing aid is a nonionic surfactant.

[0012] (8) The upstream fiber layer or the downstream fiber layer has, on its upstream fiber layer side, a functional agent having antibacterial, antifungal, or antiallergenic properties in addition to the antiviral agent. (9) An intermediate layer containing an adsorbent is provided between the upstream fiber layer and the downstream fiber layer. (10) A filter medium in which a processing solution containing an antiviral agent and a dispersing aid is applied to the upstream fiber layer or the upstream fiber layer side surface of the downstream fiber layer by impregnation or spray processing.

[0013] (11) The pH of the machining fluid is 3.0 or more and 6.0 or less.

[0014] The antiviral air filter material of the present invention is produced by a manufacturing method in which a processing solution containing an antiviral agent and a dispersing aid and having a pH of 3.0 to 6.0 is applied by impregnation or spraying to the surface of an upstream fiber layer or a downstream fiber layer facing the upstream fiber layer, and the upstream fiber layer or the downstream fiber layer is then superimposed, resulting in the upstream fiber layer having a contact angle with water of 60° or less and the downstream fiber layer having a contact angle with water of 90° or more.

[0015] According to the present invention, an air filter is provided having a configuration in which the upstream fiber layer is hydrophilic and the downstream fiber layer is water-repellent, so that moisture in the air containing viruses does not remain on the surface of the upstream fiber layer but is easily taken into the interior of the filter medium, and the moisture remains on the surface of the downstream fiber layer, trapping the viruses and increasing the contact rate with the antiviral agent that inactivates the viruses; the interaction between the antiviral agents is alleviated by a dispersing aid, preventing a decrease in antiviral performance due to aggregation; and the virus inactivation efficiency is further increased by uniformly attaching the antiviral agent to the fibers, so that sufficient antiviral properties can be exhibited even with a small amount of attachment.

[0016] The present invention will be described in detail below.

[0017] The antiviral air filter medium of the present invention is a filter medium for antiviral air filters having an upstream fiber layer with a contact angle with water of 60° or less and a downstream fiber layer with a contact angle with water of 90° or more, wherein the upstream fiber layer or the downstream fiber layer has an antiviral agent and a dispersing aid on the surface facing the upstream fiber layer, and the solids mass ratio of the antiviral agent to the dispersing aid (solids mass of antiviral agent / solids mass of dispersing aid) is 0.20 to 5.0.

[0018] The filter material for air filter of the present invention that adopts this structure is considered to achieve the effect of the present invention by the following mechanism.First, as mentioned above, in order to trap the moisture in the air that contains virus in filter material, the air filter is made of upstream fiber layer hydrophilic and downstream fiber layer water-repellent structure, so that the moisture in the air that contains virus can easily penetrate, not remaining on the surface of upstream fiber layer but being taken into the inside of filter material, and virus is difficult to penetrate into downstream fiber layer, so that virus can remain on the surface of the upstream layer side of downstream fiber layer.Therefore, it is preferable to apply antiviral agent to the surface of the upstream fiber layer side of upstream fiber layer or downstream fiber layer, and antiviral agent can also be applied to the surface of the upstream fiber layer side of both upstream fiber layer and downstream fiber layer.

[0019] The hydrophilicity and water repellency of the fiber layer are determined by the contact angle with water. The contact angle refers to the angle between the liquid surface and the solid surface (the angle inside the liquid) where the free surface of a stationary liquid contacts a solid wall. When the fiber layer surface is held horizontally, a contact angle of 60° or less with water is considered hydrophilic, and a contact angle of 90° or more is considered water repellent. Note that water may penetrate the fiber layer, resulting in no water droplets on the surface of the fiber layer; this is also considered hydrophilic. Moisture in the air containing viruses easily penetrates the interior of a hydrophilic fiber layer, particularly enveloped viruses such as influenza viruses, which have hydrophilic surfaces. In contrast, viruses are less likely to penetrate the interior of a water-repellent fiber layer and are less likely to be released to the outside of the filter.

[0020] Antiviral agents are highly biocidal and reactive, so if they aggregate due to interactions between the agents, their high antiviral performance can be significantly reduced. By using a dispersing aid to mitigate interactions between the agents, the agents can be dispersed and their original antiviral performance can be maintained without being reduced, allowing the antiviral agent to be uniformly applied to the filter media. These effects maximize the efficiency of contact between the virus and the antiviral agent.

[0021] The basis weight of the solid content of the antiviral agent is preferably 0.01 to 4.0% and more preferably 0.05 to 2.0% of the basis weight of the upstream fiber layer or downstream fiber layer containing the antiviral agent. When the basis weight is 0.01% or more, high antiviral performance can be achieved, and when the basis weight is 4.0% or less, aggregation of the antiviral agent can be further suppressed.

[0022] Examples of the fiber materials constituting the upstream fiber layer and the downstream fiber layer include glass, polyolefin, polyester, polyamide, vinylon, cellulose pulp, etc., and examples of the fiber layer form include paper, nonwoven fabric, knitted fabric, mesh, etc., among which airlaid nonwoven fabric, wet-laid nonwoven fabric, spunbonded nonwoven fabric, meltblown nonwoven fabric, thermal-bonded nonwoven fabric, stitch-bonded nonwoven fabric, needle-punched nonwoven fabric, and spunlace nonwoven fabric are preferred from the viewpoint of ease of handling. In particular, the downstream fiber layer, which plays a role in preventing viruses from escaping to the outside as much as possible, is preferably a meltblown nonwoven fabric. From the viewpoint of high dust removal performance, the meltblown nonwoven fabric is preferably an electret nonwoven fabric that has been subjected to electret processing. Furthermore, the average fiber diameter of the meltblown nonwoven fabric is preferably 6 μm or less, more preferably 3 μm or less. This can better prevent viruses from leaking to the outside beyond the downstream fiber layer.

[0023] As the antiviral agent, known antiviral agents can be used, and examples thereof include metal nanoparticles such as silver and copper; metal oxides such as copper oxide and copper sulfate; supports in which a metal such as silver or copper is attached to a carrier such as zeolite, silica gel, glass, calcium phosphate, zirconium phosphate, calcium silicate, magnesium aluminometasilicate, potassium titanate, or zinc oxide; alcohol-based compounds, phenol-based compounds, quaternary ammonium salts, benzoic acids, chlorhexidine, sorbic acids, carboxylic acids, aldehydes, ionic surfactants, plant essential oils, and components or derivatives derived from natural products such as catechins and tannins.

[0024] In particular, antiviral agents having metal atoms are compatible with fibers and are easy to impregnate or knead, making them preferable as antiviral agents of the present invention. Furthermore, antiviral agents having metal atoms exhibit their effects slowly, so if they come into contact with viruses only a few times, they do not inactivate viruses. However, in the configuration of the present invention in which viruses are confined within the filter medium, the number of times the antiviral agent comes into contact with viruses increases, and the agent is more effective.

[0025] Antiviral agents that are ionic organic compounds are also preferred for the present invention. Ionic organic compounds are highly reactive with viruses, and therefore have a high inactivation rate when they come into contact with viruses. In the present invention, the compounds are uniformly dispersed within the filter medium, allowing for efficient contact with viruses.

[0026] Furthermore, air filters are replaced or cleaned frequently, and antiviral agents containing natural products such as catechins and tannins, which are highly irritating to the skin and have excellent safety, or derivatives thereof are also preferred for the present invention.

[0027] The antiviral agent used in the present invention preferably further has antibacterial, antifungal, or antiallergenic properties, which can suppress deterioration over time and maintain the performance of the air filter for a longer period of time.

[0028] Furthermore, if the antiviral agent also has antibacterial, antifungal, or antiallergenic properties, there is no need to add a different substance to exhibit these properties, which is preferable because there is no possibility of functional degradation due to interactions between the antiviral agent and the different substances.

[0029] Furthermore, examples of antiviral agents with antibacterial properties include compounds having metal atoms such as silver-copper-zinc-supported zeolite.Furthermore, examples of antiviral agents with antifungal properties include organic compounds having ionic properties such as quaternary ammonium salts.Furthermore, examples of antiviral agents with antiallergenic properties include naturally-derived components such as natural plant extracts or derivatives thereof.

[0030] In the present invention, the upstream fiber layer or the downstream fiber layer may further contain a functional agent having antibacterial, antifungal, or antiallergenic properties in addition to the antiviral agent, thereby protecting the filter medium from attached bacteria, mold, and allergens, suppressing deterioration over time, and maintaining air filter performance for a longer period of time.

[0031] As the antibacterial agent, known antibacterial agents can be used, and examples thereof include inorganic antibacterial agents such as nanoparticles of metals such as zinc, zeolite, silica gel, glass, calcium phosphate, zirconium phosphate, calcium silicate, magnesium aluminometasilicate, potassium titanate, supports in which a metal such as zinc is attached to a carrier such as zinc oxide, and metal oxides such as zinc oxide and titanium dioxide; carbamates such as 3-iodo-2-propynyl butylcarbamate; and benzalkonium chloride.

[0032] As the antifungal agent, known antifungal agents can be used, and examples thereof include benzimidazoles such as 2-(4-thiazolyl)-benzimidazole (thiabendazole) and methyl-2-benzimidazole carbamate (carbendazim), sulfamides such as N-dichlorofluoromethylthio-N',N'-dimethyl-N-phenylsulfamide (dichlooanid) and N-dichlorofluoromethylthio-N',N'-dimethyl-N-p-tolylsulfamide (trifluanid), 2-bromo-2-nitropropane-1,3-diol, orthophenylphenol, etc. Furthermore, some of the above-mentioned antibacterial agents have antifungal properties, and these can also be used appropriately.

[0033] The antiallergen agent may be a known antiallergen agent, for example, alkaline earth metal salts such as calcium salts and strontium salts, zirconium salts such as zirconyl chloride, zirconium hydroxide, and zirconium carbonate, aluminum salts such as alum and aluminum sulfate, etc. In addition, some of the above-mentioned antibacterial agents and antifungal agents have antiallergenic properties, and these can also be used as appropriate.

[0034] The amount of the antiviral agent impregnated is preferably 0.05 to 2.0% and more preferably 0.1 to 1.0% relative to the basis weight of the upstream fiber layer or downstream fiber layer containing the antiviral agent. An amount of 0.05% or more allows the agent to fully exert its effect as a functional agent, while an amount of 2.0% or less reduces interference with the highly reactive antiviral agent and prevents a decrease in antiviral properties. Furthermore, if the functional agent is highly water-soluble, it will be eluted by the moisture on the filter medium, so it is preferable to use a water-insoluble functional agent.

[0035] The antiviral air filter medium of the present invention has a dispersing aid on the surface of the upstream fiber layer or downstream fiber layer facing the upstream fiber layer. This allows the antiviral agent to be dispersed more uniformly. The solids mass ratio of the antiviral agent to the dispersing aid (solids mass of the antiviral agent / solids mass of the dispersing aid) is 0.20 to 5.0, preferably 0.25 to 2.5. If the ratio is lower than 0.20, the antiviral agent will not be dispersed well and will aggregate, and if the ratio is higher than 5.0, the amount of dispersing aid will be excessive, causing a decrease in the antiviral properties of the antiviral agent.

[0036] Examples of dispersing aids generally include polycarboxylic acids, naphthalenesulfonic acid-formalin condensation agents, polyethylene glycol, polycarboxylic acid partial alkyl esters, polyethers, polyalkylene polyamines, alkylsulfonic acids, quaternary ammonium agents, higher alcohol alkylene oxides, polyhydric alcohol esters, polyalkyl polyamines, polyphosphates, carboxymethyl cellulose, and polysaccharides.

[0037] In particular, nonionic surfactants are preferred, and low molecular weight compounds are even more preferred. A low molecular weight compound is defined as a compound with a molecular weight of 1,000 or less. Nonionic surfactants can further suppress the effect on highly reactive antiviral agents. Furthermore, low molecular weight compounds less likely to interfere with contact between the antiviral agent and the virus.

[0038] When used as an air filter, a configuration in which an intermediate layer containing an adsorbent is provided between the upstream and downstream fiber layers is also possible. The presence of an intermediate layer containing an adsorbent allows odorous organic low-molecular-weight compounds such as ammonia and toluene to be encapsulated, preventing their release from the filter material and improving air purification performance. Furthermore, the structure allows viruses to remain in the intermediate layer, thereby enabling greater internal containment. Typical adsorbents include activated alumina, activated carbon, activated carbon fiber, silica gel, and zeolite, with activated carbon being preferred in terms of odorant adsorption effectiveness. Furthermore, an antiviral agent can be impregnated into the interior or surface of the adsorbent, and a configuration in which an adsorbent impregnated with an antiviral agent is introduced into the intermediate layer is preferred. This allows for efficient inactivation of viruses remaining in the intermediate layer. In addition to antiviral agents, functional agents with antibacterial, antifungal, or antiallergenic properties can also be impregnated. This prevents the interior of the intermediate layer from becoming a breeding ground for bacteria and mold. The adsorbent may also be impregnated into the upstream or downstream fiber layer rather than the intermediate layer.

[0039] It is also possible to incorporate a flame retardant aid into the intermediate layer. Typical examples include phosphorus-based flame retardants, nitrogen-based flame retardants, halogen-based flame retardants, bromine-based flame retardants, and composites thereof, as well as magnesium hydroxide, aluminum hydroxide, antimony-based, thermally expandable graphite, and silicone-based flame retardants. The flame retardant aid can be attached to the fibers of the upstream or downstream fiber layer, but may react with the antiviral agent, making it preferable to attach it to a layer that does not contain the antiviral agent. The flame retardant may also be attached to the upstream or downstream fiber layer rather than the intermediate layer, and flame-retardant fibers in which the flame retardant is kneaded into the fibers may also be used. In particular, if the flame retardant is highly water-soluble, it will dissolve in the moisture attached to the filter material, so it is preferable to use a water-insoluble flame retardant. Furthermore, considering environmental impact, phosphate flame retardants that do not contain halogen elements can be used regardless of the filter material's application. They are often stable compounds at a pH of around 3.0 to 6.0, and are compatible with many antiviral agents. In particular, it is more preferable to use a water-insoluble phosphorus-based flame retardant.

[0040] When the filter medium has an upstream fiber layer and a downstream fiber layer bonded together, the peel strength of the two layers is preferably 0.5N or more when measured according to JIS L 1086 (2013) standard 7.10.1. By being 0.5N or more, peeling between the upstream fiber layer and the downstream fiber layer is unlikely to occur, and the influence during molding processing or advanced processing is reduced. It is preferable to use an adhesive to bond the upstream fiber layer and the downstream fiber layer, and the adhesive generally includes aqueous systems such as melamine resin, phenolic resin, vinyl acetate resin, etc., chemical reaction systems such as epoxy resin, urethane resin, solvent-based, hot melt-based, etc. In particular, hot melt-based adhesives are preferred in terms of the processability, workability, and cost of the filter medium.

[0041] When only the upstream fiber layer and the downstream fiber layer are bonded, the adhesive is 1.0 to 20.0 g / m ２ It is preferable that the density is 1.0 g / m ２ When the thickness is 20.0 g / m or more, the adhesion between the upstream fiber layer and the downstream fiber layer becomes more sufficient. ２ If the thickness is less than this, it is possible to further prevent the antiviral agent attached to the surface of the upstream fiber layer or the downstream fiber layer on the upstream fiber layer side from being covered with the adhesive, thereby preventing a decrease in antiviral performance.

[0042] Furthermore, when at least one intermediate layer is present between the upstream fiber layer and the downstream fiber layer, the adhesive preferably accounts for 5% to 40% of the basis weight of the intermediate layer. When the adhesive accounts for 5% or more, the adhesion between the upstream fiber layer and the downstream fiber layer is more sufficient, while when the adhesive accounts for 40% or less, the antiviral agent attached to the surface of the upstream fiber layer or the downstream fiber layer facing the upstream fiber layer is more effectively prevented from being covered by the adhesive, thereby preventing a decrease in antiviral performance. Particularly when the intermediate layer does not contain fibers, a more preferable basis weight is 15% to 40%.

[0043] In the present invention, the method for impregnating the upstream fiber layer or downstream fiber layer with the antiviral agent and dispersing aid is preferably to mix the antiviral agent and dispersing aid in an aqueous solvent in the same bath to prepare a processing liquid, and then impregnate or spray-apply the fibers with the processing liquid. Alternatively, the antiviral agent and dispersing aid may be introduced during the production of the fiber layer by kneading them into molten fibers or mixing them with a binder resin. When using other functional agents, the antiviral agent and dispersing aid may be mixed in an aqueous solvent to prepare a processing liquid, and the processing liquid may be impregnated or spray-applied to the fibers, and then the functional agent may be mixed in an aqueous solvent to prepare a processing liquid, and then the processing liquid may be impregnated or spray-applied to the fibers. Alternatively, the antiviral agent, dispersing aid, and functional agent may be mixed in the same bath with an aqueous solvent to prepare a processing liquid, and then the processing liquid may be impregnated or spray-applied to the fibers. Alternatively, the antiviral agent, dispersing aid, and functional agent may be introduced during the production of the fiber layer by kneading them into molten fibers or mixing them with a binder resin, as with the antiviral agent. When mixing a functional agent with an antiviral agent in the same bath, poor compatibility between the agents can lead to concerns about agent aggregation, so it is preferable to impregnate them in a separate process. It is preferable to stir the processing solution until just before impregnating or spraying it onto the fiber, as this can prevent aggregation of the antiviral agent. To improve the stability of the processing solution, the pH of the processing solution is preferably 3.0 or higher and 6.0 or lower, and more preferably 3.5 or higher and 5.0 or lower. A pH of 3.0 or higher ensures that the processing solution has an appropriate acidity and is less likely to damage the fiber, while a pH of 6.0 or lower reduces the possibility that the solution stability of each agent in the processing solution will decrease over time.

[0044] A typical processing method includes applying a processing solution containing an antiviral agent and a dispersing aid and having a pH of 3.0 to 6.0 by impregnation or spraying to the surface of the upstream fiber layer or the downstream fiber layer facing the upstream fiber layer, and then overlapping the upstream fiber layer or the downstream fiber layer to form the upstream fiber layer with a contact angle with water of 60° or less and the downstream fiber layer with a contact angle with water of 90° or more.

[0045] The aqueous solvent mentioned above includes water alone, or an aqueous solution containing a water-soluble organic solvent such as a lower alcohol such as methanol or ethanol, a lower ketone such as acetone or methyl ethyl ketone, a lower carboxylic acid such as acetic acid, or a glycol such as ethylene glycol, propylene glycol, or diethylene glycol, and can be selected depending on the type of antiviral agent, etc.

[0046] The method for drying the filter medium to which the processing liquid is applied is not particularly limited, but a hot air drying method, a Yankee drum method, or the like is preferably used. The drying temperature is preferably 100 to 230°C, and more preferably 110 to 150°C. By setting the drying temperature to 100°C or higher, the drying time can be sufficiently shortened. Furthermore, by setting the drying temperature to 230°C or lower, the decomposition of the antiviral agent, dispersing aid, and functional agent can be further suppressed, and the antiviral properties can be fully exhibited.

[0047] The filter material of the present invention is suitable for use in air filters, particularly as filters for air purifiers and cabin filters for automobiles, and can be processed into pleats or other shapes and used as a filter unit.In order to maintain the pleat shape of the filter, it is more preferable to use a fiber layer with a stiffness of 300 mg or more measured by Gurley type.

[0048] The present invention will be described in more detail below using examples, but the present invention is not necessarily limited to these. The results of each example and comparative example are shown in Tables 1 and 2. First, the relevant measurement and evaluation methods will be described.

[0049] (1) Basis weight: Leave the sample at room temperature of 24°C and 60% RH for 8 hours or more, calculate the mass of the sample, and calculate 1 m from the area. ２ The minimum area of ​​the sample was 0.01 m. ２ That's all.

[0050] (2) Amount of adhesion The amount of adhesion of the antiviral agent, dispersing aid, and functional agent to the fiber layer was calculated by measuring the basis weight of the fiber layer before they were impregnated or the basis weight of the fiber layer without them being kneaded in, and the basis weight of the fiber layer after they were impregnated or the basis weight after they were kneaded in under the conditions of (1), and calculating the difference between these values ​​to calculate the total amount of adhesion. Next, the total amount of adhesion was multiplied by the solid mass ratio of both substances to calculate the amount of adhesion of all components.

[0051] (3) Hydrophilicity Confirmation Test 50 μL of distilled water was dropped from a height of 5 mm onto the surface of a 100 mm × 100 mm fiber layer, and the permeability was visually confirmed. Five seconds after the drop, the state of the water droplets on the fiber layer was evaluated according to the following criteria: ⊚: Distilled water has soaked into the fiber layer, and no water droplets remain on the fiber layer. ◯: Water droplets are present on the fiber layer, and the contact angle is 60° or less. △: Water droplets are present on the fiber layer, and the contact angle is greater than 60° and less than 90°. ×: Water droplets are present on the fiber layer, and the contact angle is 90° or greater.

[0052] (4) Antiviral Test According to JIS L 1922 (2016) (Testing Method for Antiviral Performance of Textile Products (Plaque Assay Method)), 0.4 g of sample was placed in a vial, inoculated with 0.2 ml of virus solution, and left at 25°C for 2 hours. 20 ml of SCDLP medium was then added to wash out the virus from the sample, and the virus infectivity of the washed-out solution was measured by the plaque assay method. The antiviral activity value was calculated according to the following formula. Furthermore, for a blank, the same procedure as above was performed without using the sample, and the virus infectivity was calculated. Antiviral activity value = log (infectivity of blank after 2 hours of action) - log (infectivity of sample after 2 hours of action). A standard cloth (cotton) is generally used as the blank. The type of virus used in the test was influenza virus (H1N1).

[0053] The calculated antiviral activity values ​​were evaluated according to the following criteria: ◎: Antiviral activity value of 3.0 or more ○: Antiviral activity value of 2.0 or more but less than 3.0 △: Antiviral activity value of 1.0 or more but less than 2.0 ×: Antiviral activity value of less than 1.0 (5) Antibacterial Test According to JIS L 1902 (2015) (Antibacterial activity test method and antibacterial effect of textile products (bacterial liquid absorption method)), 0.4 g of sample was placed in a vial, 0.2 ml of test bacteria liquid was added dropwise, and the vial was incubated at 37°C for 18 to 24 hours, after which 20 ml of washout liquid was added to wash out the test bacteria from the test piece, and the number of viable bacteria in the washout liquid was measured by the pour plate culture method. The antibacterial activity value was calculated according to the following formula. Antibacterial activity value = [log (viable bacteria count after incubation of blank) - log (viable bacteria count immediately after inoculation of blank)] - [log (viable bacteria count after incubation of sample) - log (viable bacteria count immediately after inoculation of sample)] For the blank, the same procedure as above was carried out without using the sample, and the viable bacteria count was measured. Standard cloth (cotton) was generally used as the blank. The type of bacteria used in the test was Staphylococcus aureus.

[0054] The calculated antibacterial activity value was evaluated according to the following criteria: ◎: Antibacterial activity value of 3.0 or more ○: Antibacterial activity value of 2.0 or more but less than 3.0 △: Antibacterial activity value of 1.0 or more but less than 2.0 ×: Antibacterial activity value less than 1.0 (6) Antifungal Test According to JIS Z2911 (2018) (Mold Resistance Test Method (Test of Textile Products, Wet Method)), a mixed spore suspension of mold was inoculated into the sample, and after culturing for a certain period of time, the growth state of the mycelium that appeared on the surface of the sample was observed with the naked eye or a microscope. The mold used in the test was a mixture of four species, Aspergillus niger, Penicillium citrinum, Chaetomium globosum, and Myrothecium verrucaria, in equal amounts, and the sample size was approximately 5 cm x 5 cm.

[0055] The observation results were evaluated according to the following criteria: ◎: No mycelial growth was observed in the inoculated area of ​​the sample, and a halo was observed in the medium on which the sample was placed. ○: No mycelial growth was observed in the inoculated area of ​​the sample, and no halo was observed in the medium on which the sample was placed. △: The area where mycelial growth was observed in the inoculated area of ​​the sample was less than one-third of the total area. ×: The area where mycelial growth was observed in the inoculated area of ​​the sample was more than one-third of the total area.

[0056] (7) Antiallergenicity Test (Allergen Reduction Rate Test) Each of the target allergens (cedar pollen allergen Cryj 1, mite allergen Derf 2) was dissolved in phosphate buffer to a concentration of 100 ng / ml to prepare an allergen solution.

[0057] The fiber layer was then cut into 70 mg pieces and placed in microtubes. 1 ml of the allergen solution was added to each piece, and the mixture was shaken at 4°C for 5 hours and then allowed to stand for 16 hours to react. The allergen concentration in the allergen solution reacted with the sample was measured by sandwich ELISA. The sandwich ELISA was performed as follows:

[0058] Antibodies against allergens (antigens) were immobilized on each well of a microplate. After post-coating (1% BSAPBS) and washing three times with PBS (containing 0.05% Tween 20) (the same washing method is used below), samples and standard allergens were added. After washing, labeled antibodies against allergens were added, followed by streptavidin HRPO. After washing, o-phenylenediamine was added, and H ２ SO ４ After stopping the reaction by adding the above solution, the absorbance at 490 nm was measured using a microplate reader.

[0059] Separately, a calibration curve of absorbance vs. allergen concentration was prepared using the standard allergen solution, the allergen concentration was calculated, and the allergen reduction rate was calculated using the following formula: Allergen reduction rate (%) = (B - A) / B x 100 A: Allergen concentration in the allergen solution after sample reaction B: Allergen concentration in the allergen solution unreacted with the sample The observation results were evaluated according to the following criteria. ◎: Allergen reduction rate is 98% or more ○: Allergen reduction rate is 90% or more to less than 98% △: Allergen reduction rate is 50% or more to less than 90% ×: Allergen reduction rate is less than 50% [Example 1] (Upstream fiber layer) 30 parts by mass of polyester staple fiber (polyethylene terephthalate, melting point 265°C) with a fineness of 16 dt, 20 parts by mass of heat-fusible polyester staple fiber (core: polyethylene terephthalate, melting point 265°C, sheath: modified polyester, melting point 155°C) with a fineness of 8 dt, and 50 parts by mass of heat-fusible polyester staple fiber (core: polyethylene terephthalate, melting point 265°C, sheath: modified polyester, melting point 180°C) with a fineness of 4.4 dt were mixed, and the mixture was passed through an opener and a carding machine to spin a web, which was then cross-lapped to obtain a target mass and passed through an air-through heating furnace on a transfer conveyor to obtain a web with a basis weight of 70 g / m ２ A thermal bonded nonwoven fabric having a thickness of 0.4 mm was obtained.

[0060] A pH 7.0 processing solution, prepared by mixing silver-copper-zinc-supported zeolite ("Agion" (registered trademark) AM Slurry, manufactured by Sciessent LLC) as an antiviral agent and a nonionic surfactant ("Textport SN-10", manufactured by Nicca Chemical Co., Ltd.) as a dispersing aid, in water, was placed in an impregnation tank, and the thermal bond nonwoven fabric was passed through the impregnation tank to be impregnated with the processing solution, and then passed through an air-through heating furnace to form an upstream fiber layer. The concentration of the processing solution was such that the amount of silver-copper-zinc-supported zeolite attached was 3.5 g / m ２ , the amount of nonionic surfactant attached was 3.5 g / m ２ It was adjusted so that

[0061] Therefore, the solids mass ratio of the antiviral agent to the dispersing aid (solids mass of the antiviral agent / solids mass of the dispersing aid) was 3.5 / 3.5 = 1.0, and the basis weight of the solids mass of the antiviral agent relative to the basis weight of the upstream fiber layer was 3.5 / 70 = 0.05 (5.0%).

[0062] (Downstream fiber layer) A polypropylene resin layer having an average fiber diameter of 30.0 μm and a basis weight of 30 g / m spun by a spunbond method. ２ The downstream fiber layer was obtained.

[0063] (Filter medium) The obtained upstream fiber layer and downstream fiber layer were filled with a polyethylene hot melt resin at 6.0 g / m ２ The fiber layers were combined together to obtain a filtering medium for air filters.

[0064] [Example 2] (Upstream fiber layer) The concentration of the processing solution was adjusted to a value of 0.7 g / m ２ , and 0.7 g / m of nonionic surfactant ２ An upstream fiber layer was obtained in the same manner as in Example 1, except that the thickness was adjusted to be as follows:

[0065] Therefore, the solids mass ratio of the antiviral agent to the dispersing aid (solids mass of the antiviral agent / solids mass of the dispersing aid) was 0.7 / 0.7 = 1.0, and the basis weight of the solids mass of the antiviral agent relative to the basis weight of the upstream fiber layer was 0.7 / 70 = 0.01 (1.0%).

[0066] (Downstream fiber layer) A polypropylene resin layer having an average fiber diameter of 2.0 μm and a basis weight of 30 g / m is melt-blown. ２ Next, the nonwoven fabric was run along the water surface of a water tank to which pure water was supplied, and a slit-shaped suction nozzle was brought into contact with the surface of the nonwoven fabric to suck the water, thereby allowing the water to penetrate into the entire surface of the fiber layer. After draining the water, the nonwoven fabric was allowed to dry naturally, thereby obtaining an electret downstream fiber layer.

[0067] (Filter Medium) The fiber layers were combined with each other in the same manner as in Example 1 to obtain a filter medium for an air filter.

[0068] Example 3 (Upstream Fiber Layer) A thermal-bonded nonwoven fabric was obtained in the same manner as in Example 1. A pH 7.0 processing solution was added to an impregnation tank, which was a mixture of water and a quaternary ammonium salt (Niccanon RB-40, manufactured by Nicca Chemical Co., Ltd.) as an antiviral agent and a nonionic surfactant (Textport SN-10, manufactured by Nicca Chemical Co., Ltd.) as a dispersing aid. The thermal-bonded nonwoven fabric was passed through the impregnation tank to be impregnated with the processing solution, and then passed through an air-through heating furnace to form an upstream fiber layer. The concentration of the processing solution was adjusted so that the amount of quaternary ammonium salt attached was 0.7 g / m. ２ , the amount of nonionic surfactant attached was 0.7 g / m ２ It was adjusted so that

[0069] Therefore, the solids mass ratio of the antiviral agent to the dispersing aid (solids mass of the antiviral agent / solids mass of the dispersing aid) was 0.7 / 0.7 = 1.0, and the basis weight of the solids mass of the antiviral agent relative to the basis weight of the upstream fiber layer was 0.7 / 70 = 0.01 (1.0%).

[0070] (Downstream Fiber Layer) A downstream fiber layer was obtained in the same manner as in Example 2.

[0071] (Filter Medium) The fiber layers were combined with each other in the same manner as in Example 1 to obtain a filter medium for an air filter.

[0072] Example 4 (Upstream Fiber Layer) A thermal-bonded nonwoven fabric was obtained in the same manner as in Example 1, and a processing solution of pH 7.0, prepared by mixing water with a natural plant extract ("Allersave T-70" manufactured by Sumika Environmental Science Co., Ltd.) as an antiviral agent and a nonionic surfactant ("Textport SN-10" manufactured by Nicca Chemical Co., Ltd.) as a dispersing aid, was placed in an impregnation tank. The thermal-bonded nonwoven fabric was passed through the impregnation tank to be impregnated with the processing solution, and then passed through an air-through heating furnace to form an upstream fiber layer. The concentration of the processing solution was such that the amount of natural plant extract attached was 0.7 g / m. ２ , the amount of nonionic surfactant attached was 0.7 g / m ２ It was adjusted so that

[0073] Therefore, the solids mass ratio of the antiviral agent to the dispersing aid (solids mass of the antiviral agent / solids mass of the dispersing aid) was 0.7 / 0.7 = 1.0, and the basis weight of the solids mass of the antiviral agent relative to the basis weight of the upstream fiber layer was 0.7 / 70 = 0.01 (1.0%).

[0074] (Downstream Fiber Layer) A downstream fiber layer was obtained in the same manner as in Example 2.

[0075] (Filter Medium) The fiber layers were combined with each other in the same manner as in Example 1 to obtain a filter medium for an air filter.

[0076] Example 5 (Upstream Fiber Layer) A thermal-bonded nonwoven fabric was obtained in the same manner as in Example 1. A pH 7.0 processing solution was prepared by mixing water with silver-copper-zinc-supported zeolite ("Agion" AM Slurry, manufactured by Sciessent LLC) as an antiviral agent, a nonionic surfactant ("Textport SN-10", manufactured by Nicca Chemical Co., Ltd.) as a dispersing aid, and thiabendazole ("Sintol M-30", manufactured by Sumika Environmental Science Co., Ltd.) as a fungicide other than the antiviral agent. The solution was placed in an impregnation tank, and the thermal-bonded nonwoven fabric was passed through the impregnation tank to be impregnated with the processing solution. The fabric was then passed through an air-through heating furnace to form an upstream fiber layer. The concentration of the processing solution was adjusted so that the amount of silver-copper-zinc-supported zeolite attached was 0.7 g / m. ２ , the amount of nonionic surfactant attached was 0.7 g / m ２ , the amount of thiabendazole attached was 0.7 g / m ２ It was adjusted to be.

[0077] Therefore, the solids mass ratio of the antiviral agent to the dispersing aid (solids mass of the antiviral agent / solids mass of the dispersing aid) was 0.7 / 0.7=1.0, the basis weight of the solids mass of the antiviral agent relative to the basis weight of the upstream fiber layer was 0.7 / 70=0.01 (1.0%), and the basis weight of the solids mass of the antifungal agent relative to the basis weight of the upstream fiber layer was 0.7 / 70=0.01 (1.0%).

[0078] (Downstream Fiber Layer) A downstream fiber layer was obtained in the same manner as in Example 2.

[0079] (Filter Medium) The fiber layers were combined with each other in the same manner as in Example 1 to obtain a filter medium for an air filter.

[0080] Example 6 (Upstream Fiber Layer) The upstream fiber layer was obtained in the same manner as in Example 2.

[0081] (Downstream fiber layer) An electret nonwoven fabric was obtained in the same manner as in Example 2, and a processing solution of pH 7.0, prepared by mixing thiabendazole ("Synthol M-30" manufactured by Sumika Environmental Science Co., Ltd.), an antifungal agent as a functional agent other than an antiviral agent, with water, was spray-coated, and dried at 110°C to obtain a downstream fiber layer. The concentration of the processing solution was such that the amount of thiabendazole attached was 0.3 g / m ２ Therefore, the basis weight of the solid content mass of the antifungal agent relative to the basis weight of the downstream fiber layer was 0.3 / 30=0.01 (1.0%).

[0082] (Filter Medium) The fiber layers were combined with each other in the same manner as in Example 1 to obtain a filter medium for an air filter.

[0083] [Example 7] (Upstream fiber layer) 30 parts by mass of polyester staple fibers (polyethylene terephthalate, melting point 265°C) having a fineness of 16 dt, 20 parts by mass of heat-bonded polyester staple fibers (core: polyethylene terephthalate, melting point 265°C, sheath: modified polyester, melting point 155°C) having a fineness of 8 dt, and 50 parts by mass of heat-bonded polyester staple fibers (core: polyethylene terephthalate, melting point 265°C, sheath: modified polyester, melting point 180°C) having a fineness of 4.4 dt were mixed, and the mixture was passed through an opener and a carding machine to spin a web. The web was then cross-lapped to a target mass and passed through an air-through heating furnace on a transfer conveyor to form a web with a basis weight of 70 g / m. ２ An upstream fiber layer of thermal bonded nonwoven fabric having a thickness of 0.4 mm was obtained.

[0084] (Downstream fiber layer) A spunbond nonwoven fabric was obtained in the same manner as in Example 1, and a processing solution of pH 7.0, which was a mixture of silver-copper-zinc-supported zeolite ("Agion" AM Slurry, manufactured by Sciessent LLC) as an antiviral agent and a nonionic surfactant ("Textport SN-10", manufactured by Nicca Chemical Co., Ltd.) as a dispersing aid, was spray-coated onto the fabric, followed by drying at 110°C to obtain a downstream fiber layer. The concentration of the processing solution was such that the amount of silver-copper-zinc-supported zeolite attached was 0.3 g / m ２, the amount of nonionic surfactant attached was 0.3 g / m ２ It was adjusted to be.

[0085] Therefore, the solids mass ratio of the antiviral agent to the dispersing aid (solids mass of the antiviral agent / solids mass of the dispersing aid) was 0.3 / 0.3 = 1.0, and the basis weight of the solids mass of the antiviral agent relative to the basis weight of the downstream fiber layer was 0.3 / 30 = 0.01 (1.0%).

[0086] (Filter Medium) The fiber layers were combined with each other in the same manner as in Example 1 to obtain a filter medium for an air filter.

[0087] Example 8 (Upstream Fiber Layer) The upstream fiber layer was obtained in the same manner as in Example 7.

[0088] (Downstream fiber layer) A meltblown nonwoven fabric was obtained in the same manner as in Example 2, and a processing solution of pH 7.0, which was a mixture of silver-copper-zinc-supported zeolite ("Agion" AM Slurry, manufactured by Sciessent LLC) as an antiviral agent and a nonionic surfactant ("Textport SN-10", manufactured by Nicca Chemical Co., Ltd.) as a dispersing aid, was sprayed onto the fabric, followed by drying at 110°C to obtain a downstream fiber layer. The concentration of the processing solution was adjusted so that the amount of silver-copper-zinc-supported zeolite attached was 0.3 g / m. ２ , the amount of nonionic surfactant attached was 0.3 g / m ２ It was adjusted to be.

[0089] Therefore, the solids mass ratio of the antiviral agent to the dispersing aid (solids mass of the antiviral agent / solids mass of the dispersing aid) was 0.3 / 0.3 = 1.0, and the basis weight of the solids mass of the antiviral agent relative to the basis weight of the downstream fiber layer was 0.3 / 30 = 0.01 (1.0%).

[0090] (Filter Material) The fiber layers were combined together in the same manner as in Example 1 to obtain a filter material for an air filter of Example 8.

[0091] Example 9 (Upstream Fiber Layer) An upstream fiber layer was obtained in the same manner as in Example 7.

[0092] (Downstream fiber layer) A melt-blown nonwoven fabric was obtained in the same manner as in Example 2, and a processing solution of pH 7.0, which was a mixture of silver-copper-zinc-supported zeolite ("Agion" AM Slurry, manufactured by Sciessent LLC), a nonionic surfactant as a dispersing aid ("Textport SN-10", manufactured by Nicca Chemical Co., Ltd.), and a mildew-proofing agent thiabendazole ("Sintol M-30", manufactured by Sumika Environmental Science Co., Ltd.), was spray-coated and dried at 110°C to obtain a downstream fiber layer. The concentration of the processing solution was adjusted so that the amount of silver-copper-zinc-supported zeolite attached was 0.3 g / m. ２ , nonionic surfactant adhesion amount 0.3 g / m ２ , the amount of thiabendazole attached was 0.3 g / m ２ It was adjusted to be.

[0093] Therefore, the solids mass ratio of the antiviral agent to the dispersing aid (solids mass of the antiviral agent / solids mass of the dispersing aid) was 0.3 / 0.3 = 1.0, and the basis weight of the solids mass of the antiviral agent relative to the basis weight of the upstream fiber layer was 0.3 / 30 = 0.01 (1.0%).

[0094] (Filter Medium) The fiber layers were combined with each other in the same manner as in Example 1 to obtain a filter medium for an air filter.

[0095] Example 10 (Upstream Fiber Layer) A thermobonded nonwoven fabric was obtained in the same manner as in Example 7. A pH 7.0 processing solution prepared by mixing thiabendazole ("Synthol M-30" manufactured by Sumika Environmental Science Co., Ltd.), a fungicide, with water was placed in an impregnation tank. The thermobonded nonwoven fabric was passed through the impregnation tank to be impregnated with the processing solution, and then passed through an air-through heating furnace to form an upstream fiber layer. The concentration of the processing solution was adjusted so that the amount of thiabendazole attached was 0.7 g / m. ２ Therefore, the basis weight of the solid content mass of the antifungal agent relative to the basis weight of the upstream fiber layer was 0.7 / 70=0.01 (1.0%).

[0096] (Downstream Fiber Layer) A downstream fiber layer was obtained in the same manner as in Example 7.

[0097] (Filter medium) A filter medium for an air filter was obtained by combining the fibrous layers together in the same manner as in Example 1. [Example 11] (Upstream fibrous layer) An upstream fibrous layer was obtained in the same manner as in Example 7.

[0098] (Downstream fiber layer) A spunbond nonwoven fabric was obtained in the same manner as in Example 1, and a processing solution was prepared in the same manner as in Example 7. A small amount of a pH adjuster (aqueous weak acid solution) was added to adjust the pH to 5.0, and the solution was spray-coated and dried at 110°C to obtain a downstream fiber layer. The concentration of the processing solution was adjusted so that the silver-copper-zinc-supported zeolite deposition amount was 0.3 g / m ２ , the amount of nonionic surfactant attached was 0.3 g / m ２ It was adjusted to be.

[0099] Therefore, the solids mass ratio of the antiviral agent to the dispersing aid (solids mass of the antiviral agent / solids mass of the dispersing aid) was 0.3 / 0.3 = 1.0, and the basis weight of the solids mass of the antiviral agent relative to the basis weight of the downstream fiber layer was 0.3 / 30 = 0.01 (1.0%).

[0100] (Filter Medium) The fiber layers were combined with each other in the same manner as in Example 1 to obtain a filter medium for an air filter.

[0101] Comparative Example 1 (Upstream Fiber Layer) A thermal-bonded nonwoven fabric was obtained in the same manner as in Example 7. A pH 7.0 processing solution, prepared by mixing silver-copper-zinc-supported zeolite ("Agion" AM Slurry, manufactured by Sciessent LLC) as an antiviral agent in water, was placed in an impregnation tank. The thermal-bonded nonwoven fabric was passed through the impregnation tank to be impregnated with the processing solution, and then passed through an air-through heating furnace to form an upstream fiber layer. The concentration of the processing solution was such that the amount of silver-copper-zinc-supported zeolite attached was 0.7 g / m. ２ It was adjusted to be.

[0102] Therefore, the basis weight of the solid content mass of the antiviral agent relative to the basis weight of the upstream fiber layer was 0.7 / 70=0.01 (1.0%).

[0103] (Downstream Fiber Layer) A downstream fiber layer was obtained in the same manner as in Example 2.

[0104] (Filter Medium) The fiber layers were combined with each other in the same manner as in Example 1 to obtain a filter medium for an air filter.

[0105] [Comparative Example 2] (Upstream fiber layer) The concentration of the processing solution was adjusted to a value of 0.7 g / m ２ , and 7.0 g / m of nonionic surfactant ２ An upstream fiber layer was obtained in the same manner as in Example 1, except that the thickness was adjusted to be as follows:

[0106] Therefore, the solids mass ratio of the antiviral agent to the dispersing aid (solids mass of antiviral agent / solids mass of the dispersing aid) was 0.7 / 7.0 = 0.10, and the basis weight of the solids mass of the antiviral agent relative to the basis weight of the upstream fiber layer was 0.7 / 70 = 0.01 (1.0%).

[0107] (Downstream Fiber Layer) A downstream fiber layer was obtained in the same manner as in Example 2.

[0108] (Filter Medium) The fiber layers were combined with each other in the same manner as in Example 1 to obtain a filter medium for an air filter.

[0109] Comparative Example 3 (Upstream Fiber Layer) An upstream fiber layer was obtained in the same manner as in Example 7.

[0110] (Downstream fiber layer) A melt-blown nonwoven fabric was obtained in the same manner as in Example 2, and a processing solution of pH 7.0, which was prepared by mixing a natural plant extract ("Allersave T-70" manufactured by Sumika Environmental Science Co., Ltd.) as an antiviral agent and a nonionic surfactant ("Textport SN-10" manufactured by Nicca Chemical Co., Ltd.) as a dispersing aid in water, was sprayed onto the fabric, and the fabric was dried at 110°C to obtain a downstream fiber layer. The concentration of the processing solution was such that the amount of the natural plant extract attached was 0.3 g / m ２ , nonionic surfactant adhesion amount 0.3 g / m ２ The hydrophilicity of this downstream fiber layer was evaluated as ○ (water droplets were present on the fiber layer, and the contact angle was 60° or less).

[0111] Therefore, the solids mass ratio of the antiviral agent to the dispersing aid (solids mass of the antiviral agent / solids mass of the dispersing aid) was 0.3 / 0.3 = 1.0, and the basis weight of the solids mass of the antiviral agent relative to the basis weight of the upstream fiber layer was 0.3 / 30 = 0.01 (1.0%).

[0112]

[0113]

[0114] The filter medium of the present invention can be suitably used for air filters, particularly as filters for air cleaners and cabin filters for automobiles.

Claims

1. The filter material for antiviral air filters has an upstream fiber layer having a contact angle with water of 60° or less and a downstream fiber layer having a contact angle with water of 90° or more, wherein the filter material has an antiviral agent and a dispersion aid on the surface of the upstream fiber layer or the downstream fiber layer facing the upstream fiber layer, and the solids mass ratio of the antiviral agent to the dispersion aid (solids mass of the antiviral agent / solids mass of the dispersion aid) is 0.20 to 5.

0.

2. 2. The filter material for antiviral air filters according to claim 1, wherein the basis weight of the solid content mass of the antiviral agent is 0.01 to 4.0% of the basis weight of the upstream fiber layer or the downstream fiber layer containing the antiviral agent.

3. 3. The antiviral air filter medium according to claim 1, wherein the downstream fiber layer is an electret nonwoven fabric.

4. The antiviral air filter medium according to claim 1 or 2, wherein the antiviral agent contains a compound having a metal atom.

5. The antiviral air filter medium according to claim 1 or 2, wherein the antiviral agent contains an organic compound having ionic properties.

6. A filter material for an antiviral air filter as described in claim 5, wherein the organic compound having ionic properties is a quaternary ammonium salt.

7. The antiviral air filter medium according to claim 1 or 2, wherein the antiviral agent contains a naturally occurring component or a derivative thereof.

8. 3. The antiviral air filter medium according to claim 1, wherein the antiviral agent further has antibacterial, antifungal or antiallergenic properties.

9. 3. The antiviral air filter medium according to claim 1, wherein the dispersing aid is a nonionic surfactant.

10. The filter material for antiviral air filters according to claim 1 or 2, wherein a functional agent having antibacterial, antifungal or antiallergenic properties is further present on the surface of the upstream fiber layer or the downstream fiber layer facing the upstream fiber layer in addition to the antiviral agent.

11. The antiviral air filter medium according to claim 1 or 2, further comprising an intermediate layer containing an adsorbent between the upstream fiber layer and the downstream fiber layer.

12. 3. The method for producing a filter material for an antiviral air filter according to claim 1 or 2, wherein a processing solution containing an antiviral agent and a dispersion aid is applied by a processing method such as impregnation or spraying to a surface of the upstream fiber layer or a surface of the downstream fiber layer facing the upstream fiber layer.

13. The method for producing a filter material for an antiviral air filter according to claim 12, wherein the pH of the processing liquid is 3.0 or more and 6.0 or less.